Causes and Effect of Cancer
Content
The Effects of Smoking on Human Health
The effects of smoking on human health are serious and in many cases, deadly. There are approximately 4000 chemicals in cigarettes, hundreds of which are toxic. The ingredients in cigarettes affect everything from the internal functioning of organs to the efficiency of the body's immune system. The effects of cigarette smoking are destructive and widespread. Smoking Effects on the Human Body
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Toxic ingredients in cigarette smoke travel throughout the body, causing damage in several different ways. • Nicotine reaches the brain within 10 seconds after smoke is inhaled. It has been found in every part of the body and in breast milk. • Carbon monoxide binds to hemoglobin in red blood cells, preventing affected cells from carrying a full load of oxygen. • Cancer-causing agents (carcinogens) in tobacco smoke damage important genes that control the growth of cells, causing them to grow abnormally or to reproduce too rapidly. • The carcinogen benzo(a)pyrene binds to cells in the airways and major organs of smokers. • Smoking affects the function of the immune system and may increase the risk for respiratory and other infections. • There are several likely ways that cigarette smoke does its damage. One is oxidative stress that mutates DNA, promotes atherosclerosis, and leads to chronic lung injury. Oxidative stress is thought to be the general mechanism behind the aging process, contributing to the development of cancer, cardiovascular disease, and COPD. • The body produces antioxidants to help repair damaged cells. Smokers have lower levels of antioxidants in their blood than do nonsmokers. • Smoking is associated with higher levels of chronic inflammation, another damaging process that may result in oxidative stress.
Cancer Statistics
When people think of cancers caused by smoking, the first one that comes to mind is alwayslung cancer. Most cases of lung cancer death, close to 90% in men, and 80% in women
are caused by cigarette smoking. There are several other forms of cancer attributed to smoking as well, and they include cancer of the oral cavity, pharynx, larynx, esophagus, bladder, stomach, cervix, kidney and pancreas, and acute myeloid leukemia. The list of additives allowed in the manufacture of cigarettes consists of 599 possible ingredients. When burned, cigarette smoke contains over 4000 chemicals, with over 40 of them being known carcinogens. • Cancer is the second leading cause of death and was among the first diseases causally linked to smoking. • Lung cancer is the leading cause of cancer death, and cigarette smoking causes most cases. • Compared to nonsmokers, men who smoke are about 23 times more likely to develop lung cancer and women who smoke are about 13 times more likely. Smoking causes about 90% of lung cancer deaths in men and almost 80% in women. • In 2003, an estimated 171,900 new cases of lung cancer occurred and approximately 157,200 people died from lung cancer. • The 2004 Surgeon General's report adds more evidence to previous conclusions that smoking causes cancers of the oral cavity, pharynx, larynx, esophagus, lung and bladder. • Cancer-causing agents (carcinogens) in tobacco smoke damage important genes that control the growth of cells, causing them to grow abnormally or to reproduce too rapidly. • Cigarette smoking is a major cause of esophageal cancer in the United States. Reductions in smoking and smokeless tobacco use could prevent many of the approximately 12,300 new cases and 12,100 deaths from esophgeal cancer that occur annually. • The combination of smoking and alcohol consumption causes most laryngeal cancer cases. In 2003, an estimated 3800 deaths occurred from laryngeal cancer. • In 2003, an estimated 57,400 new cases of bladder cancer were diagnosed and an estimated 12,500 died from the disease. • For smoking-attributable cancers, the risk generally increases with the number of cigarettes smoked and the number of years of smoking, and generally decreases after quitting completely. • Smoking cigarettes that have a lower yield of tar does not substantially reduce the risk for lung cancer. • Cigarette smoking increases the risk of developing mouth cancers. This risk also increases among people who smoke pipes and cigars. • Reductions in the number of people who smoke cigarettes, pipes, cigars, and other tobacco products or use smokeless tobacco could prevent most of the estimated 30,200 new cases and 7,800 deaths from oral cavity and pharynx cancers annually in the United States. New cancers confirmed by this report: • The 2004 Surgeon General's report newly identifies other cancers caused by smoking, including cancers of the stomach, cervix, kidney, and pancreas and acute myeloid leukemia. • In 2003, an estimated 22,400 new cases of stomach cancer were diagnosed, and an estimated 12,100 deaths were expected to occur. • Former smokers have lower rates of stomach cancer than those who continue to smoke. • For women, the risk of cervical cancer increases with the duration of smoking. • In 2003, an estimated 31,900 new cases of kidney cancer were diagnosed, and an estimated 11,900 people died from the disease. • In 2003, an estimated 30,700 new cases of pancreatic cancer were diagnosed, attributing to 30,000 deaths. The median time from diagnosis to death from pancreatic cancer is about 3 months. • In 2003, approximately 10,500 cases of acute myeloid leukemia were diagnosed in adults. • Benzene is a known cause of acute myleoid leukemia, and cigarette smoke is a major source of benzene exposure. Among U.S. smokers, 90% of benzene exposures come from cigarettes.
Health effects of tobacco
The health effects of tobacco are the circumstances, mechanisms, and factors of tobacco consumption on human health. Epidemiological research has been focused primarily on cigarette tobacco smoking,which has been studied more extensively than any other form of consumption. Tobacco is the single greatest cause of preventable death globally.Tobacco use leads most commonly to diseases affecting the heart and lungs, with smoking being a major risk factor forheart attacks, strokes, chronic obstructive pulmonary disease (COPD) (including emphysemaand chronic bronchitis), and cancer (particularly lung cancer, cancers of the larynx and mouth, and pancreatic cancer). It also causes peripheral vascular disease and hypertension. The effects depend on the number of years that a person smokes and on how much the person smokes. Starting smoking earlier in life and smoking cigarettes higher in tar increases the risk of these diseases. Also, environmental tobacco smoke, or secondhand smoke, has been shown to cause adverse health effects in people of all ages.Cigarettes sold in underdeveloped countriestend to have higher tar content, and are less likely to be filtered, potentially increasing vulnerability to tobacco-related disease in these regions.The World Health Organization(WHO) estimates that tobacco caused 5.4 million deaths in 2004 and 100 million deaths over the course of the 20th century.Similarly, the United States Centers for Disease Control and Prevention describes tobacco use as "the single most important preventable risk to human health in developed countries and an important cause of premature death worldwide. Smoke contains several carcinogenic pyrolytic products that bind to DNA and cause manygenetic mutations. There are over 19 known chemical carcinogens in cigarette smoke[citation needed]. Tobacco also contains nicotine, which is a highly addictive psychoactivechemical. When tobacco is smoked, nicotine causes physical and psychological dependency. Tobacco use is a significant factor in miscarriages among pregnant smokers, it contributes to a number of other threats to the health of the fetus such as premature births and low birth weight and increases by 1.4 to 3 times the chance for Sudden Infant Death Syndrome (SIDS).The result of scientific studies done in neonatal rats seems to indicate that exposure to cigarette smoke in the womb may reduce the fetal brain's ability to recognize hypoxic conditions, thus increasing the chance of
accidental asphyxiation. Incidence of impotence is approximately 85 percent higher in male smokers compared to non-smokers,and is a key factor causing erectile dysfunction(ED).
Health effects
A person's increased risk of contracting disease is directly proportional to the length of time that a person continues to smoke as well as the amount smoked. However, if someone stops smoking, then these chances gradually decrease as the damage to their body is repaired. A year after quitting, the risk of contracting heart disease is half that of a continuing smoker.[14] The health risks of smoking are not uniform across all smokers. Risks vary according to amount of tobacco smoked, with those who smoke more at greater risk. Light cigarette smoking still poses a significant (though reduced) health risk, as does pipe and cigar smoking. Smoking so-called "light" cigarettes does not reduce the risk. Tobacco use most commonly leads to diseases affecting the heart and lungs and will most commonly affect areas such as hands or feet with first signs of smoking related health issues showing up as numbness, with smoking being a major risk factor for heart attacks, Chronic Obstructive Pulmonary Disease (COPD),emphysema, and cancer, particularly lung cancer,
cancers of the larynx and mouth, and pancreatic cancer. Overall life expectancy is also reduced in regular smokers, with estimates ranging from 10[15] to 17.9 [16] years fewer than nonsmokers. [17] About two thirds of male smokers will die of illness due to smoking.[18] The association of smoking with lung cancer is strongest, both in the public perception and etiologically. People who have smoked tobacco at some point have about a one in ten chance of developing lung cancer during their lifetime.[19] If one looks at men who continue to smoke tobacco, the risk increases to one in six.[20] Historically, lung cancer was considered to be a rare disease prior to World War Iand was perceived as something most physicians would never see during their career. With the postwar rise in popularity of cigarette smoking came a virtual epidemic of lung cancer.[21][22] [edit]Mortality Male and female smokers lose an average of 13.2 to 14.5 years of life, respectively.[23] According to the results of a 14 year study of 34,486 male British doctors, at least half of all lifelong smokers die earlier as a result of smoking.[15] Smokers are three times as likely to die before the age of 60 or 70 as non-smokers.[24][25][26] In the United States alone, cigarette smoking and exposure to tobacco smoke accounts for roughly one in five,[27] or at at least 443,000 premature deaths annually.[28] "In the United States alone, tobacco kills the equivalent of three jumbo jets full of people crashing every day, with no survivors, 365 days of the year." -ABC's Peter Jennings[29] On a worldwide basis, it's 1 jumbo jet per hour, 24 hours a day, 365 days of the year. -WHO[30] [edit]Cancer The primary risks of tobacco usage include many forms of cancer, particularly lung cancer, [31] kidney cancer,[32] cancer of the larynx andhead and neck, breast cancer,[33][34] bladder cancer, [35] cancer of the esophagus,[36] cancer of the pancreas[37] and stomach cancer.[38] There is some evidence suggesting a small increased risk of myeloid leukaemia, squamous cell sinonasal cancer, liver cancer, colorectal cancer, cancers of the gallbladder, the adrenal gland, the small intestine, and various childhood cancers. Recent studies have established a stronger relationship between tobacco smoke, including secondhand smoke, and cervical cancer in women.[39] The risk of dying from lung cancer before age 85 is 22.1% for a male smoker and 11.9% for a female smoker, in the absence of competing causes of death. The corresponding estimates for lifelong nonsmokers are a 1.1% probability of dying from lung cancer before age 85 for a man of European descent, and a 0.8% probability for a woman.[40]
Health Effects of Cigarette Smoking
Overview
Smoking harms nearly every organ of the body. Smoking causes many diseases and reduces the health of smokers in general.1
Smoking and Death
Smoking causes death. • The adverse health effects from cigarette smoking account for an estimated 443,000 deaths, or nearly one of every five deaths, each year in the United States.2,3 • More deaths are caused each year by tobacco use than by all deaths from human immunodeficiency virus (HIV), illegal drug use, alcohol use, motor vehicle injuries, suicides, and murders combined.2,4 • Smoking causes an estimated 90% of all lung cancer deaths in men and 80% of all lung cancer deaths in women.1 • An estimated 90% of all deaths from chronic obstructive lung disease are caused by smoking.1
Smoking and Increased Health Risks
Compared with nonsmokers, smoking is estimated to increase the risk of— • coronary heart disease by 2 to 4 times,1,5 • stroke by 2 to 4 times,1,6 • men developing lung cancer by 23 times,1 • women developing lung cancer by 13 times,1 and • dying from chronic obstructive lung diseases (such as chronic bronchitis and emphysema) by 12 to 13 times.1
Smoking and Cardiovascular Disease
• Smoking causes coronary heart disease, the leading cause of death in the United
States.1 • Cigarette smoking causes reduced circulation by narrowing the blood vessels (arteries) and puts smokers at risk of developing peripheral vascular disease (i.e., obstruction of the large arteries in the arms and legs that can cause a range of problems from pain to tissue loss or gangrene).1,7 • Smoking causes abdominal aortic aneurysm (i.e., a swelling or weakening of the main artery of the body—the aorta—where it runs through the abdomen).1
Smoking and Respiratory Disease
• Smoking causes lung cancer.1,2 • Smoking causes lung diseases (e.g., emphysema, bronchitis, chronic airway
obstruction) by damaging the airways and alveoli (i.e., small air sacs) of the lungs.1,2
Smoking and Cancer
Smoking causes the following cancers:1
• Acute myeloid leukemia • Bladder cancer
• Cancer of the cervix • Cancer of the esophagus • Kidney cancer • Cancer of the larynx (voice box) • Lung cancer • Cancer of the oral cavity (mouth) • Cancer of the pharynx (throat) • Stomach cancer • Cancer of the uterus
What Are the Medical Consequences of Tobacco Use?
Cigarette smoking kills an estimated 440,000 U.S. citizens each year—more than alcohol, illegal drug use, homicide, suicide, car accidents, and AIDS combined. Between 1964 and 2004, more than 12 million Americans died prematurely from smoking, and another 25 million U.S. smokers alive today will most likely die of a smoking-related illness. Cigarette smoking harms nearly every organ in the body. It has been conclusively linked to cataracts and pneumonia, and accounts for about one-third of all cancer deaths. The overall rates of death from cancer are twice as high among smokers as nonsmokers, with heavy smokers having rates that are four times greater than those of nonsmokers. Foremost among the cancers caused by tobacco use is lung cancer—cigarette smoking has been linked to about 90 percent of all cases of lung cancer, the number one cancer killer of both men and women. Smoking is also associated with cancers of the mouth, pharynx, larynx, esophagus, stomach, pancreas, cervix, kidney, bladder, and acute myeloid leukemia.
Using advanced neuroimaging technology, scientists can see the dramatic effect of cigarette smoking on the brain and body and are finding a marked decrease in the levels of monoamine oxidase (MAO B), an important enzyme that is responsible for the breakdown of dopamine. (Source: Fowler et al., 2003)
In addition to cancer, smoking causes lung diseases such as chronic bronchitis and emphysema, and it has been found to exacerbate asthma symptoms in adults and children. About 90 percent of all deaths from chronic obstructive pulmonary diseases are attributable to cigarette smoking. It has also been well documented that smoking substantially increases the risk of heart disease, including stroke, heart attack, vascular disease, and aneurysm. Smoking causes coronary heart disease, the leading cause of death in the United States: cigarette smokers are 2–4 times more likely to develop coronary heart disease than nonsmokers. Exposure to high doses of nicotine, such as those found in some insecticide sprays, can be extremely toxic as well, causing vomiting, tremors, convulsions, and death. In fact, one drop of pure nicotine can kill a person. Nicotine poisoning has been reported from accidental ingestion of insecticides by adults and ingestion of tobacco products by children and pets. Death usually results in a few minutes from respiratory failure caused by paralysis. Although we often think of medical consequences that result from direct use of tobacco products, passive or secondary smoke also increases the risk for many diseases. Environmental tobacco smoke is a major source of indoor air contaminants; secondhand smoke is estimated to cause
approximately 3,000 lung cancer deaths per year among nonsmokers and contributes to more than 35,000 deaths related to cardiovascular disease. Exposure to tobacco smoke in the home is also a risk factor for new cases and increased severity of childhood asthma. Additionally, dropped cigarettes are the leading cause of residential fire fatalities, leading to more than 1,000 deaths each year.
Sticky, brown tar coats the lungs of tobacco smokers. Along with thousands of other damaging chemicals, tar can lead to lung cancer and acute respiratory diseases.
Side effects of chewing tobacco are stained teeth, bad breath,
sores on the gums and in the mouth that are stubborn to heal and other dental problems. Some of the effects on dental health are escalated by the sugar that is added to the tobacco during processing to improve the taste. The habit can also affect a person's ability to taste and smell. After prolonged use there is a risk of developing oral cancer which may become apparent through a sore that does not heal, a white patch, prolonged sore throat, difficulty chewing, or a feeling there is a lump in the throat. A person should stop chewing tobacco to reduce the side effects and health risks associated with it. Chewing or smokeless tobacco contains nicotine a very addictive substance. The nicotine gets into the bloodstream through absorption in the mouth and is slower acting than getting nicotine from smoking a cigarette. The most serious health risk associated with the smokeless habit is cancer. The habit of snuff or chewing tobacco can be considered by many as a very
unclean habit. The substance is held in the mouth and then spit out. Most chewers have a spit can that they carry around and spit into periodically. Some people may choose to engage in this habit because they believe it is not as harmful as smoking cigarettes. However, this is not necessarily true. The substance is still absorbed into the bloodstream and the side effects of chewing tobacco can be detrimental to health and can even lead to developing a serious illness such as cancer. For those who want to quit, there is hope found in the Word of God. "And Caleb stilled the people before Moses, and said, Let us go up at once, and possess it; for we are well able to overcome it" (Numbers 13:30). Other serious health problems associated with the smokeless habit include an increased heart rate and blood pressure. People who are engaged in this habit shouldstop chewing tobacco before they have a heart attack or suffer from a stroke. Heart attack and stroke can happen because the arteries constrict; there is an increased risk of blood clots; both of these effects are caused by the nicotine. Oral or mouth cancer are not the only types of cancer associated with a smokeless habit; some of the cancer-causing chemicals can get into other vital organs such as the stomach, esophagus, bowels, and bladder. High doses of nicotine can cause respiratory and digestive distress. Quitting may be very difficult because of the nicotine addiction and may take some time but there is help out there for anyone who is serious about quitting. There are some good websites on the Internet that provide some valuable information on quitting. Mint leaf is a substance that is harmless but has a consistency like smokeless snuff. A person who wants to quit gradually can substitute mint leaf for part of the tobacco until they are eventually chewing the mint leaf and no longer need the nicotine. Another idea that might help to stop chewing tobacco would be to chew the mint leaf by itself as long as possible. When a craving gets to be unbearable add some of the tobacco in with the mint leaf. Each time this happens add a smaller amount until no longer needed. Some of the ways to quit the smokeless habit is by using a nicotine patch or gum and asking a doctor about taking antidepressants that may help with withdrawal symptoms. As a substitute a person can try chewing gum, hard candy, and other foods such as dried fruit or jerky. There is also a snuff that closely resembles tobacco called mint leaf that can be used as a substitution. For those who have great difficulty in quitting but do not want to suffer with the side effects of chewing tobacco should consider counseling and getting advice from a doctor. The withdrawals are primarily caused from the lack of nicotine and may include anxiety, depression, headaches, and fatigue. There are twenty-eight different chemicals in snuff that are considered carcinogens or cancer-causing agents. Research has shown that there is actually more nicotine in a plug of chewing tobacco than in a cigarette. In addition, there are chemicals such as formaldehyde and arsenic in snuff. Even without considering other chemicals the nicotine alone should be enough of a reason to
stop chewing tobacco. Nicotine is a potent substance and has even been used as insecticide. Nicotine cross the blood-brain barrier and can be absorbed into the skin. Using the substance causes the body to increase the flow of adrenaline which causes an increase in heart rate and blood pressure as well as increasing insulin. The byproduct of nicotine can stay in the body for 48 hours after being used. Nicotine also increases dopamine levels in the brain which is why a person feels good when they use it. This is one of the main reasons that a person becomes addicted. In addition, using snuff has been linked to developing Parkinson's and Alzheimer's disease. These risks are related to nicotine and how it affects the brain. The best way to help someone with an addiction is to give him or her information that will educate them about the detriments to their body. There is a lot of information on the Internet that can be downloaded or requested through the mail by doing a search for side effects of chewing tobacco
Tobacco and cancer risk - statistics
Summary
Smoking is the single greatest avoidable risk factor for cancer; in the UK, it is the cause of more than a quarter (28%) of all deaths from cancer and has killed an estimated 6.6 million people over the last 50 years.2 A study published in December 2011 estimated that smoking causes nearly a fifth of all cancer cases in the UK.35 Worldwide, tobacco consumption caused an estimated 100 million deaths in the last century and if current trends continue it will kill 1,000 million in the 21st century. Around half of all regular smokers will die from the habit, half of these in middle age.1
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More than one in five (21%) British adults currently smokes Smoking causes around 88% of lung cancer deaths in men and around
84% of lung cancer deaths in women in the UK
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Smoking prevalence (any tobacco product) in British men was 30% in 2002 compared with 82% in 1948 Table 1.1 shows the strength of evidence for an increased risk of cancer due to tobacco consumption.
Lung cancer
Smoking causes around 88% of male and around 84% of female deaths from lung cancer in the UK. 2The estimate of cancer cases due to smoking in the UK is almost identical (87% of cases in men and 84% in women). This figure includes around 1,000 lung cancer cases due to exposure to environmental tobacco smoke in lifelong non-smokers.35 The link between lung cancer and cigarette smoking was first established in 1950, with a study showing a 26-fold increased risk of lung cancer among smokers of 15-24 cigarettes a day, compared with non-smokers. 3 Recently, a 50-year follow-up study of smoking and lung cancer in British doctors showed a similar 25-fold increase in lung cancer risk in men smoking 25 cigarettes a day or more, compared to lifelong non-smokers. 27 Lung cancer risk increases with both duration and intensity of smoking 4. (Figure 1.15)
Download this chart (16KB) Back to top ^ The effect of stopping smoking at any age on the excess risk of lung cancer is striking. Figure 1.2shows the cumulative risk of lung cancer among men in the UK at age 75 according to age at which they stopped smoking 6.
Download this chart (14.5KB) The interaction between smoking and other harmful exposures can result in a much greater risk in people exposed to both. The risks of smoking and exposure
to radon interact multiplicatively, and reanalysis of data from European casecontrol studies shows that most of the additional cases of lung cancer in people exposed to radon in the home are in smokers. 7 Studies have shown that exposure to asbestos increases the risk of lung cancer by around ten-fold in non-smokers, while in smokers exposed to asbestos, there is a 100-fold increase in risk 8. Exposure to environmental tobacco smoke also causes lung cancer. The most recent meta-analyses show that exposure to ETS at work or in the home increases the risk of lung cancer among non-smokers by about a quarter, while heavy exposure at work doubles the risk. 9, 11 Exposure to ETS may also increase the risk of pharyngeal and laryngeal cancer. 14 It has been estimated that exposure to ETS in the home causes around 11,000 deaths in the UK each year from lung cancer, stroke and heart disease combined. 10. Male lung cancer incidence rates peaked in the early 1970s, reflecting the peak in smoking prevalence 20-30 years earlier. Rates in women have stabilised, after increasing throughout the 1970s and 1980s. Forecasting suggests that female lung cancer mortality rates will reach current male levels within the next ten years and then fall, while deaths will continue to fall in men 12.
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Types of tobacco
Most UK evidence on tobacco and cancer risk is based on smokers of manufactured filtered cigarettes. Risk is generally higher among smokers of filter-less cigarettes, high tar cigarettes, and black tobacco. Hand-rolled cigarettes have a stronger effect than manufactured cigarettes on risk of cancer of the oral cavity and pharynx 17, 18. The proportion of male British smokers consuming self-rolled cigarettes increased to 37% in 2009 from 25% in 1998, and among women it increased from 8% to 21% over the same period 19. Pipe and cigar smokers have an increased risk of lung and upper aerodigestive tract cancer compared with non-smokers 4. A cohort study reported a seven-fold increase in risk of liver cancer in current cigar smokers and another study reported a three-fold increase in risk for current cigar or pipe smokers 20, 21. Heavy pipe or cigar smoking also increases risk of bladder, bowel, stomach and pancreas cancers 4. The proportion of all men in Britain smoking cigars in 2009 was 2%, compared with 16% in 1978. Less than 1% of men in Britain smoke a pipe19. Long-term users of smokeless (chewing) tobacco have an increased risk for oral, pancreatic and oesophageal cancer. Much of the evidence for such an association comes from South East Asia, where betel quid is widely used. A recent review summarising the evidence about cancer and smokeless tobacco to date gave risk ratios for oral cancer in smokeless tobacco users in India and
other Asian countries of about five, and in Sudan of about seven. The risk ratio for oral cancer in smokeless tobacco users in the USA and Canada was 2.6. Risk estimates of 1.6 and 1.8 were given for oesophageal and pancreatic cancer in Northern European smokeless tobacco users. 22 In India, the risk of oral cancer is greatest in chewers of mixtures containing tobacco, but the risk in chewers of betel quid without tobacco is higher than non-users. 23. While the use of smokeless tobacco is not widespread in the UK, it is relatively common among some South Asian communities (Figure 1.333). The prevalence of tobacco chewing increases with age, especially among Bangladeshi men and women. Betel quid (with and without tobacco) is the most commonly used product 25.
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Other smoking related cancers
While deaths from lung cancer account for around a 69% of smoking related cancer deaths in the UK,2 smoking is also an established risk factor for cancers of the oesophagus, larynx, pharynx, oral cavity, pancreas, bladder, nasal cavity and sinuses, stomach, liver, kidney, cervix and myeloid leukaemia 4. The International Agency for Research on Cancer in 2009 stated there is now sufficient evidence that smoking is also a cause of bowel cancer and ovarian (mucinous) cancer.14 After lung cancer, the upper aerodigestive tract cancers (larynx, oral and pharynx and oesophagus) have the highest smoking population attributable fractions (PAFs), of around 65% or higher.35 Also, alcohol consumption in combination with smoking greatly increases the risk of upper aerodigestive tract cancers (see section on alcohol) 13. Smoking cessation reduces the risk for most of these cancers. The risk for cancers of the upper aerodigestive tract in ex-smokers becomes lower than that of a current smoker within five years, although risk is still higher than someone who has never smoked 20 or more years after stopping, and the risk for bladder cancer is also higher than in never-smokers 20 years after giving up 15-16,28.
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Smoking prevalence
More than one in five British adults currently smokes. In 2009, the difference in smoking prevalence between men (22%) and women (20%) was significant. The average consumption of cigarettes per smoker per day is 14 in men and 13 in women 19. The peak smoking prevalence is in younger adults, after which prevalence falls. Only 14% of British people over 60 years old smoke cigarettes. Almost 40% of regular smokers began smoking regularly before the age of 16. 19
Download this chart As Figure 1.4 shows, smoking rates are higher in among manual workers compared with non-manual. Among managerial and professional workers in England, in 2009, smoking prevalence was 15%, compared with 28% of routine and manual workers 19. Geographical variations in smoking prevalence within the UK largely reflect these socioeconomic differences. Smoking rates in Scotland are higher than elsewhere in the UK with 25% of men and women smoking. 19 The prevalence of smoking peaked in the late 1940s for British males at 82% and the 1970s for British females at 44% 26. The epidemic of smoking related cancers in the UK has peaked and recent years have seen record falls in death rates for smoking related diseases. (Figure 1.519).
How common is lung cancer?
Lung cancer is the most common cause of death due to cancer in both men and women throughout the world. The American Cancer Society estimated that 222,520 new cases of lung cancer in the U.S. will be diagnosed and 157,300 deaths due to lung cancer would occur in 2010. According to the U.S. National Cancer Institute, approximately one out of every 14 men and women in the U.S. will be diagnosed with cancer of the lung at some point in their lifetime.
Lung cancer is predominantly a disease of the elderly; almost 70% of people diagnosed with lung cancer are over 65 years of age, while less than 3% of lung cancers occur in people under 45 years of age.
Lung cancer was not common prior to the 1930s but increased dramatically over the following decades as tobacco smokingincreased. In many developing countries, the incidence of lung cancer is beginning to fall following public education about the dangers of cigarette smoking and the introduction of effective smoking-cessation programs. Nevertheless, lung cancer remains among the most common types of cancers in both men and women worldwide. In the U.S., lung cancer has surpassed breast cancer as the most common cause of cancer-related deaths in women.
What causes lung cancer?
Smoking The incidence of lung cancer is strongly correlated with cigarette smoking, with about 90% of lung cancers arising as a result of tobacco use. The risk of lung cancer increases with the number of cigarettes smoked and the time over which smoking has occurred; doctors refer to this risk in terms of pack-years of smoking history (the number of packs of cigarettes smoked per day multiplied by the number of years smoked). For example, a person who has smoked two packs of cigarettes per day for 10 years has a 20 pack-year smoking history. While the risk of lung cancer is increased with even a 10-pack-year smoking history, those with 30pack-year histories or more are considered to have the greatest risk for the development of lung cancer. Among those who smoke two or more packs of cigarettes per day, one in seven will die of lung cancer. Pipe and cigar smoking also can cause lung cancer, although the risk is not as high as with cigarette smoking. Thus, while someone who smokes one pack of cigarettes per day has a risk for the development of lung cancer that is 25 times higher than a nonsmoker, pipe and cigar smokers have a risk of lung cancer that is about five times that of a nonsmoker. Tobacco smoke contains over 4,000 chemical compounds, many of which have been shown to be cancer-causing or carcinogenic. The two primary carcinogens in tobacco smoke are chemicals known as nitrosamines and polycyclic aromatic hydrocarbons. The risk of developing lung cancer decreases each year following smoking cessation as normal cells grow and replace damaged cells in the lung. In former smokers, the risk of developing lung cancer begins to approach that of a nonsmoker about 15 years after cessation of smoking. Passive smoking Passive smoking or the inhalation of tobacco smoke by nonsmokers who share living or working quarters with smokers, also is an established risk factor for the development of lung cancer. Research has shown that nonsmokers who reside with a smoker have a 24% increase in risk for developing lung cancer when compared with nonsmokers who do not reside with a smoker. An estimated 3,000 lung cancer deaths that occur each year in the U.S. are attributable to passive smoking.
Lung diseases The presence of certain diseases of the lung, notably chronic obstructive pulmonary disease (COPD), is associated with an increased risk (four- to sixfold the risk of a nonsmoker) for the development of lung cancer even after the effects of concomitant cigarette smoking are excluded. Prior history of lung cancer Survivors of lung cancer have a greater risk of developing a second lung cancer than the general population has of developing a first lung cancer. Survivors of non-small cell lung cancers (NSCLCs, see below) have an additive risk of 1%-2% per year for developing a second lung cancer. In survivors of small cell lung cancers (SCLCs, see below), the risk for development of second lung cancers approaches 6% per year.
Carcinogensis Associated With Smokeless Tobacco Use
The effects of smoking on human health are serious and in many cases, deadly. There are approximately 4000 chemicals in cigarettes, hundreds of which are toxic. The ingredients in cigarettes affect everything from the internal functioning of organs to the efficiency of the body's immune system. The effects of cigarette smoking are destructive and widespread. Smoking Effects on the Human Body
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Toxic ingredients in cigarette smoke travel throughout the body, causing damage in several different ways. • Nicotine reaches the brain within 10 seconds after smoke is inhaled. It has been found in every part of the body and in breast milk. • Carbon monoxide binds to hemoglobin in red blood cells, preventing affected cells from carrying a full load of oxygen. • Cancer-causing agents (carcinogens) in tobacco smoke damage important genes that control the growth of cells, causing them to grow abnormally or to reproduce too rapidly. • The carcinogen benzo(a)pyrene binds to cells in the airways and major organs of smokers. • Smoking affects the function of the immune system and may increase the risk for respiratory and other infections. • There are several likely ways that cigarette smoke does its damage. One is oxidative stress that mutates DNA, promotes atherosclerosis, and leads to chronic lung injury. Oxidative stress is thought to be the general mechanism behind the aging process, contributing to the development of cancer, cardiovascular disease, and COPD. • The body produces antioxidants to help repair damaged cells. Smokers have lower levels of antioxidants in their blood than do nonsmokers. • Smoking is associated with higher levels of chronic inflammation, another damaging process that may result in oxidative stress.
Cancer Statistics
When people think of cancers caused by smoking, the first one that comes to mind is alwayslung cancer. Most cases of lung cancer death, close to 90% in men, and 80% in women
are caused by cigarette smoking. There are several other forms of cancer attributed to smoking as well, and they include cancer of the oral cavity, pharynx, larynx, esophagus, bladder, stomach, cervix, kidney and pancreas, and acute myeloid leukemia. The list of additives allowed in the manufacture of cigarettes consists of 599 possible ingredients. When burned, cigarette smoke contains over 4000 chemicals, with over 40 of them being known carcinogens. • Cancer is the second leading cause of death and was among the first diseases causally linked to smoking. • Lung cancer is the leading cause of cancer death, and cigarette smoking causes most cases. • Compared to nonsmokers, men who smoke are about 23 times more likely to develop lung cancer and women who smoke are about 13 times more likely. Smoking causes about 90% of lung cancer deaths in men and almost 80% in women. • In 2003, an estimated 171,900 new cases of lung cancer occurred and approximately 157,200 people died from lung cancer. • The 2004 Surgeon General's report adds more evidence to previous conclusions that smoking causes cancers of the oral cavity, pharynx, larynx, esophagus, lung and bladder. • Cancer-causing agents (carcinogens) in tobacco smoke damage important genes that control the growth of cells, causing them to grow abnormally or to reproduce too rapidly. • Cigarette smoking is a major cause of esophageal cancer in the United States. Reductions in smoking and smokeless tobacco use could prevent many of the approximately 12,300 new cases and 12,100 deaths from esophgeal cancer that occur annually. • The combination of smoking and alcohol consumption causes most laryngeal cancer cases. In 2003, an estimated 3800 deaths occurred from laryngeal cancer. • In 2003, an estimated 57,400 new cases of bladder cancer were diagnosed and an estimated 12,500 died from the disease. • For smoking-attributable cancers, the risk generally increases with the number of cigarettes smoked and the number of years of smoking, and generally decreases after quitting completely. • Smoking cigarettes that have a lower yield of tar does not substantially reduce the risk for lung cancer. • Cigarette smoking increases the risk of developing mouth cancers. This risk also increases among people who smoke pipes and cigars. • Reductions in the number of people who smoke cigarettes, pipes, cigars, and other tobacco products or use smokeless tobacco could prevent most of the estimated 30,200 new cases and 7,800 deaths from oral cavity and pharynx cancers annually in the United States. New cancers confirmed by this report: • The 2004 Surgeon General's report newly identifies other cancers caused by smoking, including cancers of the stomach, cervix, kidney, and pancreas and acute myeloid leukemia. • In 2003, an estimated 22,400 new cases of stomach cancer were diagnosed, and an estimated 12,100 deaths were expected to occur. • Former smokers have lower rates of stomach cancer than those who continue to smoke. • For women, the risk of cervical cancer increases with the duration of smoking. • In 2003, an estimated 31,900 new cases of kidney cancer were diagnosed, and an estimated 11,900 people died from the disease. • In 2003, an estimated 30,700 new cases of pancreatic cancer were diagnosed, attributing to 30,000 deaths. The median time from diagnosis to death from pancreatic cancer is about 3 months. • In 2003, approximately 10,500 cases of acute myeloid leukemia were diagnosed in adults. • Benzene is a known cause of acute myleoid leukemia, and cigarette smoke is a major source of benzene exposure. Among U.S. smokers, 90% of benzene exposures come from cigarettes.
Health effects of tobacco
The health effects of tobacco are the circumstances, mechanisms, and factors of tobacco consumption on human health. Epidemiological research has been focused primarily on cigarette tobacco smoking,which has been studied more extensively than any other form of consumption. Tobacco is the single greatest cause of preventable death globally.Tobacco use leads most commonly to diseases affecting the heart and lungs, with smoking being a major risk factor forheart attacks, strokes, chronic obstructive pulmonary disease (COPD) (including emphysemaand chronic bronchitis), and cancer (particularly lung cancer, cancers of the larynx and mouth, and pancreatic cancer). It also causes peripheral vascular disease and hypertension. The effects depend on the number of years that a person smokes and on how much the person smokes. Starting smoking earlier in life and smoking cigarettes higher in tar increases the risk of these diseases. Also, environmental tobacco smoke, or secondhand smoke, has been shown to cause adverse health effects in people of all ages.Cigarettes sold in underdeveloped countriestend to have higher tar content, and are less likely to be filtered, potentially increasing vulnerability to tobacco-related disease in these regions.The World Health Organization(WHO) estimates that tobacco caused 5.4 million deaths in 2004 and 100 million deaths over the course of the 20th century.Similarly, the United States Centers for Disease Control and Prevention describes tobacco use as "the single most important preventable risk to human health in developed countries and an important cause of premature death worldwide. Smoke contains several carcinogenic pyrolytic products that bind to DNA and cause manygenetic mutations. There are over 19 known chemical carcinogens in cigarette smoke[citation needed]. Tobacco also contains nicotine, which is a highly addictive psychoactivechemical. When tobacco is smoked, nicotine causes physical and psychological dependency. Tobacco use is a significant factor in miscarriages among pregnant smokers, it contributes to a number of other threats to the health of the fetus such as premature births and low birth weight and increases by 1.4 to 3 times the chance for Sudden Infant Death Syndrome (SIDS).The result of scientific studies done in neonatal rats seems to indicate that exposure to cigarette smoke in the womb may reduce the fetal brain's ability to recognize hypoxic conditions, thus increasing the chance of
accidental asphyxiation. Incidence of impotence is approximately 85 percent higher in male smokers compared to non-smokers,and is a key factor causing erectile dysfunction(ED).
Health effects
A person's increased risk of contracting disease is directly proportional to the length of time that a person continues to smoke as well as the amount smoked. However, if someone stops smoking, then these chances gradually decrease as the damage to their body is repaired. A year after quitting, the risk of contracting heart disease is half that of a continuing smoker.[14] The health risks of smoking are not uniform across all smokers. Risks vary according to amount of tobacco smoked, with those who smoke more at greater risk. Light cigarette smoking still poses a significant (though reduced) health risk, as does pipe and cigar smoking. Smoking so-called "light" cigarettes does not reduce the risk. Tobacco use most commonly leads to diseases affecting the heart and lungs and will most commonly affect areas such as hands or feet with first signs of smoking related health issues showing up as numbness, with smoking being a major risk factor for heart attacks, Chronic Obstructive Pulmonary Disease (COPD),emphysema, and cancer, particularly lung cancer,
cancers of the larynx and mouth, and pancreatic cancer. Overall life expectancy is also reduced in regular smokers, with estimates ranging from 10[15] to 17.9 [16] years fewer than nonsmokers. [17] About two thirds of male smokers will die of illness due to smoking.[18] The association of smoking with lung cancer is strongest, both in the public perception and etiologically. People who have smoked tobacco at some point have about a one in ten chance of developing lung cancer during their lifetime.[19] If one looks at men who continue to smoke tobacco, the risk increases to one in six.[20] Historically, lung cancer was considered to be a rare disease prior to World War Iand was perceived as something most physicians would never see during their career. With the postwar rise in popularity of cigarette smoking came a virtual epidemic of lung cancer.[21][22] [edit]Mortality Male and female smokers lose an average of 13.2 to 14.5 years of life, respectively.[23] According to the results of a 14 year study of 34,486 male British doctors, at least half of all lifelong smokers die earlier as a result of smoking.[15] Smokers are three times as likely to die before the age of 60 or 70 as non-smokers.[24][25][26] In the United States alone, cigarette smoking and exposure to tobacco smoke accounts for roughly one in five,[27] or at at least 443,000 premature deaths annually.[28] "In the United States alone, tobacco kills the equivalent of three jumbo jets full of people crashing every day, with no survivors, 365 days of the year." -ABC's Peter Jennings[29] On a worldwide basis, it's 1 jumbo jet per hour, 24 hours a day, 365 days of the year. -WHO[30] [edit]Cancer The primary risks of tobacco usage include many forms of cancer, particularly lung cancer, [31] kidney cancer,[32] cancer of the larynx andhead and neck, breast cancer,[33][34] bladder cancer, [35] cancer of the esophagus,[36] cancer of the pancreas[37] and stomach cancer.[38] There is some evidence suggesting a small increased risk of myeloid leukaemia, squamous cell sinonasal cancer, liver cancer, colorectal cancer, cancers of the gallbladder, the adrenal gland, the small intestine, and various childhood cancers. Recent studies have established a stronger relationship between tobacco smoke, including secondhand smoke, and cervical cancer in women.[39] The risk of dying from lung cancer before age 85 is 22.1% for a male smoker and 11.9% for a female smoker, in the absence of competing causes of death. The corresponding estimates for lifelong nonsmokers are a 1.1% probability of dying from lung cancer before age 85 for a man of European descent, and a 0.8% probability for a woman.[40]
Health Effects of Cigarette Smoking
Overview
Smoking harms nearly every organ of the body. Smoking causes many diseases and reduces the health of smokers in general.1
Smoking and Death
Smoking causes death. • The adverse health effects from cigarette smoking account for an estimated 443,000 deaths, or nearly one of every five deaths, each year in the United States.2,3 • More deaths are caused each year by tobacco use than by all deaths from human immunodeficiency virus (HIV), illegal drug use, alcohol use, motor vehicle injuries, suicides, and murders combined.2,4 • Smoking causes an estimated 90% of all lung cancer deaths in men and 80% of all lung cancer deaths in women.1 • An estimated 90% of all deaths from chronic obstructive lung disease are caused by smoking.1
Smoking and Increased Health Risks
Compared with nonsmokers, smoking is estimated to increase the risk of— • coronary heart disease by 2 to 4 times,1,5 • stroke by 2 to 4 times,1,6 • men developing lung cancer by 23 times,1 • women developing lung cancer by 13 times,1 and • dying from chronic obstructive lung diseases (such as chronic bronchitis and emphysema) by 12 to 13 times.1
Smoking and Cardiovascular Disease
• Smoking causes coronary heart disease, the leading cause of death in the United
States.1 • Cigarette smoking causes reduced circulation by narrowing the blood vessels (arteries) and puts smokers at risk of developing peripheral vascular disease (i.e., obstruction of the large arteries in the arms and legs that can cause a range of problems from pain to tissue loss or gangrene).1,7 • Smoking causes abdominal aortic aneurysm (i.e., a swelling or weakening of the main artery of the body—the aorta—where it runs through the abdomen).1
Smoking and Respiratory Disease
• Smoking causes lung cancer.1,2 • Smoking causes lung diseases (e.g., emphysema, bronchitis, chronic airway
obstruction) by damaging the airways and alveoli (i.e., small air sacs) of the lungs.1,2
Smoking and Cancer
Smoking causes the following cancers:1
• Acute myeloid leukemia • Bladder cancer
• Cancer of the cervix • Cancer of the esophagus • Kidney cancer • Cancer of the larynx (voice box) • Lung cancer • Cancer of the oral cavity (mouth) • Cancer of the pharynx (throat) • Stomach cancer • Cancer of the uterus
What Are the Medical Consequences of Tobacco Use?
Cigarette smoking kills an estimated 440,000 U.S. citizens each year—more than alcohol, illegal drug use, homicide, suicide, car accidents, and AIDS combined. Between 1964 and 2004, more than 12 million Americans died prematurely from smoking, and another 25 million U.S. smokers alive today will most likely die of a smoking-related illness. Cigarette smoking harms nearly every organ in the body. It has been conclusively linked to cataracts and pneumonia, and accounts for about one-third of all cancer deaths. The overall rates of death from cancer are twice as high among smokers as nonsmokers, with heavy smokers having rates that are four times greater than those of nonsmokers. Foremost among the cancers caused by tobacco use is lung cancer—cigarette smoking has been linked to about 90 percent of all cases of lung cancer, the number one cancer killer of both men and women. Smoking is also associated with cancers of the mouth, pharynx, larynx, esophagus, stomach, pancreas, cervix, kidney, bladder, and acute myeloid leukemia.
Using advanced neuroimaging technology, scientists can see the dramatic effect of cigarette smoking on the brain and body and are finding a marked decrease in the levels of monoamine oxidase (MAO B), an important enzyme that is responsible for the breakdown of dopamine. (Source: Fowler et al., 2003)
In addition to cancer, smoking causes lung diseases such as chronic bronchitis and emphysema, and it has been found to exacerbate asthma symptoms in adults and children. About 90 percent of all deaths from chronic obstructive pulmonary diseases are attributable to cigarette smoking. It has also been well documented that smoking substantially increases the risk of heart disease, including stroke, heart attack, vascular disease, and aneurysm. Smoking causes coronary heart disease, the leading cause of death in the United States: cigarette smokers are 2–4 times more likely to develop coronary heart disease than nonsmokers. Exposure to high doses of nicotine, such as those found in some insecticide sprays, can be extremely toxic as well, causing vomiting, tremors, convulsions, and death. In fact, one drop of pure nicotine can kill a person. Nicotine poisoning has been reported from accidental ingestion of insecticides by adults and ingestion of tobacco products by children and pets. Death usually results in a few minutes from respiratory failure caused by paralysis. Although we often think of medical consequences that result from direct use of tobacco products, passive or secondary smoke also increases the risk for many diseases. Environmental tobacco smoke is a major source of indoor air contaminants; secondhand smoke is estimated to cause
approximately 3,000 lung cancer deaths per year among nonsmokers and contributes to more than 35,000 deaths related to cardiovascular disease. Exposure to tobacco smoke in the home is also a risk factor for new cases and increased severity of childhood asthma. Additionally, dropped cigarettes are the leading cause of residential fire fatalities, leading to more than 1,000 deaths each year.
Sticky, brown tar coats the lungs of tobacco smokers. Along with thousands of other damaging chemicals, tar can lead to lung cancer and acute respiratory diseases.
Side effects of chewing tobacco are stained teeth, bad breath,
sores on the gums and in the mouth that are stubborn to heal and other dental problems. Some of the effects on dental health are escalated by the sugar that is added to the tobacco during processing to improve the taste. The habit can also affect a person's ability to taste and smell. After prolonged use there is a risk of developing oral cancer which may become apparent through a sore that does not heal, a white patch, prolonged sore throat, difficulty chewing, or a feeling there is a lump in the throat. A person should stop chewing tobacco to reduce the side effects and health risks associated with it. Chewing or smokeless tobacco contains nicotine a very addictive substance. The nicotine gets into the bloodstream through absorption in the mouth and is slower acting than getting nicotine from smoking a cigarette. The most serious health risk associated with the smokeless habit is cancer. The habit of snuff or chewing tobacco can be considered by many as a very
unclean habit. The substance is held in the mouth and then spit out. Most chewers have a spit can that they carry around and spit into periodically. Some people may choose to engage in this habit because they believe it is not as harmful as smoking cigarettes. However, this is not necessarily true. The substance is still absorbed into the bloodstream and the side effects of chewing tobacco can be detrimental to health and can even lead to developing a serious illness such as cancer. For those who want to quit, there is hope found in the Word of God. "And Caleb stilled the people before Moses, and said, Let us go up at once, and possess it; for we are well able to overcome it" (Numbers 13:30). Other serious health problems associated with the smokeless habit include an increased heart rate and blood pressure. People who are engaged in this habit shouldstop chewing tobacco before they have a heart attack or suffer from a stroke. Heart attack and stroke can happen because the arteries constrict; there is an increased risk of blood clots; both of these effects are caused by the nicotine. Oral or mouth cancer are not the only types of cancer associated with a smokeless habit; some of the cancer-causing chemicals can get into other vital organs such as the stomach, esophagus, bowels, and bladder. High doses of nicotine can cause respiratory and digestive distress. Quitting may be very difficult because of the nicotine addiction and may take some time but there is help out there for anyone who is serious about quitting. There are some good websites on the Internet that provide some valuable information on quitting. Mint leaf is a substance that is harmless but has a consistency like smokeless snuff. A person who wants to quit gradually can substitute mint leaf for part of the tobacco until they are eventually chewing the mint leaf and no longer need the nicotine. Another idea that might help to stop chewing tobacco would be to chew the mint leaf by itself as long as possible. When a craving gets to be unbearable add some of the tobacco in with the mint leaf. Each time this happens add a smaller amount until no longer needed. Some of the ways to quit the smokeless habit is by using a nicotine patch or gum and asking a doctor about taking antidepressants that may help with withdrawal symptoms. As a substitute a person can try chewing gum, hard candy, and other foods such as dried fruit or jerky. There is also a snuff that closely resembles tobacco called mint leaf that can be used as a substitution. For those who have great difficulty in quitting but do not want to suffer with the side effects of chewing tobacco should consider counseling and getting advice from a doctor. The withdrawals are primarily caused from the lack of nicotine and may include anxiety, depression, headaches, and fatigue. There are twenty-eight different chemicals in snuff that are considered carcinogens or cancer-causing agents. Research has shown that there is actually more nicotine in a plug of chewing tobacco than in a cigarette. In addition, there are chemicals such as formaldehyde and arsenic in snuff. Even without considering other chemicals the nicotine alone should be enough of a reason to
stop chewing tobacco. Nicotine is a potent substance and has even been used as insecticide. Nicotine cross the blood-brain barrier and can be absorbed into the skin. Using the substance causes the body to increase the flow of adrenaline which causes an increase in heart rate and blood pressure as well as increasing insulin. The byproduct of nicotine can stay in the body for 48 hours after being used. Nicotine also increases dopamine levels in the brain which is why a person feels good when they use it. This is one of the main reasons that a person becomes addicted. In addition, using snuff has been linked to developing Parkinson's and Alzheimer's disease. These risks are related to nicotine and how it affects the brain. The best way to help someone with an addiction is to give him or her information that will educate them about the detriments to their body. There is a lot of information on the Internet that can be downloaded or requested through the mail by doing a search for side effects of chewing tobacco
Tobacco and cancer risk - statistics
Summary
Smoking is the single greatest avoidable risk factor for cancer; in the UK, it is the cause of more than a quarter (28%) of all deaths from cancer and has killed an estimated 6.6 million people over the last 50 years.2 A study published in December 2011 estimated that smoking causes nearly a fifth of all cancer cases in the UK.35 Worldwide, tobacco consumption caused an estimated 100 million deaths in the last century and if current trends continue it will kill 1,000 million in the 21st century. Around half of all regular smokers will die from the habit, half of these in middle age.1
• •
More than one in five (21%) British adults currently smokes Smoking causes around 88% of lung cancer deaths in men and around
84% of lung cancer deaths in women in the UK
•
Smoking prevalence (any tobacco product) in British men was 30% in 2002 compared with 82% in 1948 Table 1.1 shows the strength of evidence for an increased risk of cancer due to tobacco consumption.
Lung cancer
Smoking causes around 88% of male and around 84% of female deaths from lung cancer in the UK. 2The estimate of cancer cases due to smoking in the UK is almost identical (87% of cases in men and 84% in women). This figure includes around 1,000 lung cancer cases due to exposure to environmental tobacco smoke in lifelong non-smokers.35 The link between lung cancer and cigarette smoking was first established in 1950, with a study showing a 26-fold increased risk of lung cancer among smokers of 15-24 cigarettes a day, compared with non-smokers. 3 Recently, a 50-year follow-up study of smoking and lung cancer in British doctors showed a similar 25-fold increase in lung cancer risk in men smoking 25 cigarettes a day or more, compared to lifelong non-smokers. 27 Lung cancer risk increases with both duration and intensity of smoking 4. (Figure 1.15)
Download this chart (16KB) Back to top ^ The effect of stopping smoking at any age on the excess risk of lung cancer is striking. Figure 1.2shows the cumulative risk of lung cancer among men in the UK at age 75 according to age at which they stopped smoking 6.
Download this chart (14.5KB) The interaction between smoking and other harmful exposures can result in a much greater risk in people exposed to both. The risks of smoking and exposure
to radon interact multiplicatively, and reanalysis of data from European casecontrol studies shows that most of the additional cases of lung cancer in people exposed to radon in the home are in smokers. 7 Studies have shown that exposure to asbestos increases the risk of lung cancer by around ten-fold in non-smokers, while in smokers exposed to asbestos, there is a 100-fold increase in risk 8. Exposure to environmental tobacco smoke also causes lung cancer. The most recent meta-analyses show that exposure to ETS at work or in the home increases the risk of lung cancer among non-smokers by about a quarter, while heavy exposure at work doubles the risk. 9, 11 Exposure to ETS may also increase the risk of pharyngeal and laryngeal cancer. 14 It has been estimated that exposure to ETS in the home causes around 11,000 deaths in the UK each year from lung cancer, stroke and heart disease combined. 10. Male lung cancer incidence rates peaked in the early 1970s, reflecting the peak in smoking prevalence 20-30 years earlier. Rates in women have stabilised, after increasing throughout the 1970s and 1980s. Forecasting suggests that female lung cancer mortality rates will reach current male levels within the next ten years and then fall, while deaths will continue to fall in men 12.
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Types of tobacco
Most UK evidence on tobacco and cancer risk is based on smokers of manufactured filtered cigarettes. Risk is generally higher among smokers of filter-less cigarettes, high tar cigarettes, and black tobacco. Hand-rolled cigarettes have a stronger effect than manufactured cigarettes on risk of cancer of the oral cavity and pharynx 17, 18. The proportion of male British smokers consuming self-rolled cigarettes increased to 37% in 2009 from 25% in 1998, and among women it increased from 8% to 21% over the same period 19. Pipe and cigar smokers have an increased risk of lung and upper aerodigestive tract cancer compared with non-smokers 4. A cohort study reported a seven-fold increase in risk of liver cancer in current cigar smokers and another study reported a three-fold increase in risk for current cigar or pipe smokers 20, 21. Heavy pipe or cigar smoking also increases risk of bladder, bowel, stomach and pancreas cancers 4. The proportion of all men in Britain smoking cigars in 2009 was 2%, compared with 16% in 1978. Less than 1% of men in Britain smoke a pipe19. Long-term users of smokeless (chewing) tobacco have an increased risk for oral, pancreatic and oesophageal cancer. Much of the evidence for such an association comes from South East Asia, where betel quid is widely used. A recent review summarising the evidence about cancer and smokeless tobacco to date gave risk ratios for oral cancer in smokeless tobacco users in India and
other Asian countries of about five, and in Sudan of about seven. The risk ratio for oral cancer in smokeless tobacco users in the USA and Canada was 2.6. Risk estimates of 1.6 and 1.8 were given for oesophageal and pancreatic cancer in Northern European smokeless tobacco users. 22 In India, the risk of oral cancer is greatest in chewers of mixtures containing tobacco, but the risk in chewers of betel quid without tobacco is higher than non-users. 23. While the use of smokeless tobacco is not widespread in the UK, it is relatively common among some South Asian communities (Figure 1.333). The prevalence of tobacco chewing increases with age, especially among Bangladeshi men and women. Betel quid (with and without tobacco) is the most commonly used product 25.
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Other smoking related cancers
While deaths from lung cancer account for around a 69% of smoking related cancer deaths in the UK,2 smoking is also an established risk factor for cancers of the oesophagus, larynx, pharynx, oral cavity, pancreas, bladder, nasal cavity and sinuses, stomach, liver, kidney, cervix and myeloid leukaemia 4. The International Agency for Research on Cancer in 2009 stated there is now sufficient evidence that smoking is also a cause of bowel cancer and ovarian (mucinous) cancer.14 After lung cancer, the upper aerodigestive tract cancers (larynx, oral and pharynx and oesophagus) have the highest smoking population attributable fractions (PAFs), of around 65% or higher.35 Also, alcohol consumption in combination with smoking greatly increases the risk of upper aerodigestive tract cancers (see section on alcohol) 13. Smoking cessation reduces the risk for most of these cancers. The risk for cancers of the upper aerodigestive tract in ex-smokers becomes lower than that of a current smoker within five years, although risk is still higher than someone who has never smoked 20 or more years after stopping, and the risk for bladder cancer is also higher than in never-smokers 20 years after giving up 15-16,28.
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Smoking prevalence
More than one in five British adults currently smokes. In 2009, the difference in smoking prevalence between men (22%) and women (20%) was significant. The average consumption of cigarettes per smoker per day is 14 in men and 13 in women 19. The peak smoking prevalence is in younger adults, after which prevalence falls. Only 14% of British people over 60 years old smoke cigarettes. Almost 40% of regular smokers began smoking regularly before the age of 16. 19
Download this chart As Figure 1.4 shows, smoking rates are higher in among manual workers compared with non-manual. Among managerial and professional workers in England, in 2009, smoking prevalence was 15%, compared with 28% of routine and manual workers 19. Geographical variations in smoking prevalence within the UK largely reflect these socioeconomic differences. Smoking rates in Scotland are higher than elsewhere in the UK with 25% of men and women smoking. 19 The prevalence of smoking peaked in the late 1940s for British males at 82% and the 1970s for British females at 44% 26. The epidemic of smoking related cancers in the UK has peaked and recent years have seen record falls in death rates for smoking related diseases. (Figure 1.519).
How common is lung cancer?
Lung cancer is the most common cause of death due to cancer in both men and women throughout the world. The American Cancer Society estimated that 222,520 new cases of lung cancer in the U.S. will be diagnosed and 157,300 deaths due to lung cancer would occur in 2010. According to the U.S. National Cancer Institute, approximately one out of every 14 men and women in the U.S. will be diagnosed with cancer of the lung at some point in their lifetime.
Lung cancer is predominantly a disease of the elderly; almost 70% of people diagnosed with lung cancer are over 65 years of age, while less than 3% of lung cancers occur in people under 45 years of age.
Lung cancer was not common prior to the 1930s but increased dramatically over the following decades as tobacco smokingincreased. In many developing countries, the incidence of lung cancer is beginning to fall following public education about the dangers of cigarette smoking and the introduction of effective smoking-cessation programs. Nevertheless, lung cancer remains among the most common types of cancers in both men and women worldwide. In the U.S., lung cancer has surpassed breast cancer as the most common cause of cancer-related deaths in women.
What causes lung cancer?
Smoking The incidence of lung cancer is strongly correlated with cigarette smoking, with about 90% of lung cancers arising as a result of tobacco use. The risk of lung cancer increases with the number of cigarettes smoked and the time over which smoking has occurred; doctors refer to this risk in terms of pack-years of smoking history (the number of packs of cigarettes smoked per day multiplied by the number of years smoked). For example, a person who has smoked two packs of cigarettes per day for 10 years has a 20 pack-year smoking history. While the risk of lung cancer is increased with even a 10-pack-year smoking history, those with 30pack-year histories or more are considered to have the greatest risk for the development of lung cancer. Among those who smoke two or more packs of cigarettes per day, one in seven will die of lung cancer. Pipe and cigar smoking also can cause lung cancer, although the risk is not as high as with cigarette smoking. Thus, while someone who smokes one pack of cigarettes per day has a risk for the development of lung cancer that is 25 times higher than a nonsmoker, pipe and cigar smokers have a risk of lung cancer that is about five times that of a nonsmoker. Tobacco smoke contains over 4,000 chemical compounds, many of which have been shown to be cancer-causing or carcinogenic. The two primary carcinogens in tobacco smoke are chemicals known as nitrosamines and polycyclic aromatic hydrocarbons. The risk of developing lung cancer decreases each year following smoking cessation as normal cells grow and replace damaged cells in the lung. In former smokers, the risk of developing lung cancer begins to approach that of a nonsmoker about 15 years after cessation of smoking. Passive smoking Passive smoking or the inhalation of tobacco smoke by nonsmokers who share living or working quarters with smokers, also is an established risk factor for the development of lung cancer. Research has shown that nonsmokers who reside with a smoker have a 24% increase in risk for developing lung cancer when compared with nonsmokers who do not reside with a smoker. An estimated 3,000 lung cancer deaths that occur each year in the U.S. are attributable to passive smoking.
Lung diseases The presence of certain diseases of the lung, notably chronic obstructive pulmonary disease (COPD), is associated with an increased risk (four- to sixfold the risk of a nonsmoker) for the development of lung cancer even after the effects of concomitant cigarette smoking are excluded. Prior history of lung cancer Survivors of lung cancer have a greater risk of developing a second lung cancer than the general population has of developing a first lung cancer. Survivors of non-small cell lung cancers (NSCLCs, see below) have an additive risk of 1%-2% per year for developing a second lung cancer. In survivors of small cell lung cancers (SCLCs, see below), the risk for development of second lung cancers approaches 6% per year.
Carcinogensis Associated With Smokeless Tobacco Use
