Does smoking cause cancer?
Tobacco smoke contains over 60 chemicals known to cause cancer. Certain chemicals in tobacco smoke damage an important gene called p53. The p53 gene is found in the nucleus of every cell in the human body and its main role is to prevent cancer cells evolving. Cigarette smoke is the main cause of p53 mutations in lung cancer.
Approximately one fifth of all cancer deaths in Australia are due to smoking.
Lung cancer is the most common form of cancer caused by smoking. More than 80% of cases of lung cancer are due to smoking.
Smoking also causes cancer of the tongue, mouth, throat, nose, nasal sinus, voice box, oesophagus pancreas, stomach, liver, kidney, bladder, ureter, bowel, cervix, ovary, and bone marrow (myeloid leukemia).
After you quit, your risk of cancer will be lower than the risk for those who continue to smoke. For some types of cancer your risk returns to that of someone who has never smoked.
How can smoking affect your health?
Smoking shortens lives
A large 2013 study of women in the United Kingdom found that 2 out of 3 deaths in smokers who were in their 50s, 60s, and 70s were caused by smoking. The researchers observed that continuing smokers lose at least 10 years of their lifespans, but added that smokers who quit before age 40 were able to avoid 90% of the early deaths caused by continued smoking. If the women quit before age 30, they were able to avoid more than 97% of these early deaths.
Does tobacco smoke contain harmful chemicals?
Yes. Tobacco smoke contains many chemicals that are harmful to both smokers and nonsmokers. Breathing even a little tobacco smoke can be harmful.
Of the more than 7,000 chemicals in tobacco smoke, at least 250 are known to be harmful, including hydrogen cyanide, carbon monoxide, and ammonia.
Among the 250 known harmful chemicals in tobacco smoke, at least 69 can cause cancer. These cancer-causing chemicals include the following:
- Acetaldehyde
- Aromatic amines
- Arsenic
- Benzene
- Benzo[α]pyrene
- Beryllium (a toxic metal)
- 1,3–Butadiene (a hazardous gas)
- Cadmium (a toxic metal)
- Chromium (a metallic element)
- Cumene
- Ethylene oxide
- Formaldehyde
- Nickel (a metallic element)
- Polonium-210 (a radioactive chemical element)
- Polycyclic aromatic hydrocarbons (PAHs)
- Tobacco-specific nitrosamines
- Vinyl chloride
What are some of the health problems caused by cigarette smoking?
Smoking has been found to harm nearly every bodily organ and organ system in the body and diminishes a person’s overall health.
Smoking is a leading cause of cancer and death from cancer. It causes cancers of the lung, esophagus, larynx, mouth, throat, kidney, bladder, liver, pancreas, stomach, cervix, colon, and rectum, as well as acute myeloid leukemia.
Smoking causes heart disease, stroke, aortic aneurysm (a balloon-like bulge in an artery in the chest), chronic obstructive pulmonary disease (COPD) (chronic bronchitis and emphysema), diabetes, osteoporosis, rheumatoid arthritis, age-related macular degeneration, and cataracts, and worsens asthma symptoms in adults. Smokers are at higher risk of developing pneumonia, tuberculosis, and other airway infections. In addition, smoking causes inflammation and impairs immune function.
Since the 1960s, a smoker’s risk of developing lung cancer or COPD has actually increased compared with nonsmokers, even though the number of cigarettes consumed per smoker has decreased. There have also been changes in the type of lung cancer smokers develop – a decline in squamous cell carcinomas but a dramatic increase in adenocarcinomas. Both of these effects may be due to changes in the formulation of cigarettes.
Smoking makes it harder for a woman to get pregnant. A pregnant smoker is at higher risk of miscarriage, having an ectopic pregnancy, having her baby born too early and with an abnormally low birth weight, and having her baby born with a cleft lip and/or cleft palate. A woman who smokes during or after pregnancy increases her infant’s risk of death from Sudden Infant Death Syndrome (SIDS). Men who smoke are at greater risk of erectile dysfunction.
Cigarette smoking and exposure to tobacco smoke cause about 480,000 premature deaths each year in the United States. Of these premature deaths, about 36 percent are from cancer, 39 percent are from heart disease and stroke, and 24 percent are from lung disease. Smoking is the leading cause of premature, preventable death in this country.
Regardless of their age, smokers can substantially reduce their risk of disease, including cancer, by quitting.
What are the risks of tobacco smoke to nonsmokers?
Secondhand smoke causes disease and premature death in nonsmoking adults and children. Exposure to secondhand smoke may increase the risk of heart disease by an estimated 25 to 30 percent. In the United States, exposure to secondhand smoke is thought to cause about 34,000 deaths from heart disease each year. Exposure to secondhand smoke also increases the risk of stroke by 20 to 30 percent. Pregnant women exposed to secondhand smoke are at risk of having a baby with low birth weight. Children exposed to secondhand smoke are at an increased risk of SIDS, ear infections, colds, pneumonia, and bronchitis. It can also increase the frequency and severity of asthma symptoms among children who have asthma. Being exposed to secondhand smoke slows the growth of children’s lungs and can cause them to cough, wheeze, and feel breathless.
Is smoking addictive?
Cigarettes, cigars, and other tobacco products vary widely in their content of nicotine, cancer-causing substances, and other toxicants. In a cigarette (which contains 0.49 to 0.89 gram of tobacco), the nicotine content can vary between 13.79 and 22.68 milligrams per gram of dry tobacco. In a cigar (which can contain as many as 21.5 grams of tobacco), the nicotine content can vary between 6.3 and 15.6 milligrams per gram of tobacco or 5.9 to 335.2 milligrams per cigar.
The way a person smokes a tobacco product is as important as the nicotine content of the product in determining how much nicotine gets into the body. Nicotine is absorbed into the bloodstream through the lining of the mouth and the lungs and travels to the brain in a matter of seconds. Taking more frequent and deeper puffs of tobacco smoke increases the amount of nicotine absorbed by the body.
Are other tobacco products, such as smokeless tobacco or pipe tobacco, harmful and addictive?
Yes. All forms of tobacco are harmful and addictive. There is no safe tobacco product.
In addition to cigarettes and cigars, other forms of tobacco include smokeless tobacco (also called chewing tobacco, snuff, and snus), pipes, hookahs (waterpipes), bidis, and kreteks.
- Pipes: Pipe smoking causes lung cancer and increases the risk of cancers of the mouth, throat, larynx, and esophagus.
- Hookahs or waterpipes (other names include argileh, ghelyoon, hubble bubble, shisha, boory, goza, and narghile): A hookah is a device used to smoke tobacco. The smoke passes through a partially filled water bowl before being inhaled by the smoker. Some people think hookah smoking is less harmful and addictive than smoking cigarettes, but research suggests that waterpipe smoke is at least as toxic as cigarette smoke.
- Bidis: A bidi is a flavored cigarette made by rolling tobacco in a dried leaf from the tendu tree, which is native to India. Bidi use is associated with heart attacks and cancers of the mouth, throat, larynx, esophagus, and lung.
- Kreteks: A kretek is a cigarette made with a mixture of tobacco and cloves. Smoking kreteks is associated with lung cancer and other lung diseases.
What are the immediate benefits of quitting smoking?
The immediate health benefits of quitting smoking are substantial:
- Heart rate and blood pressure, which are abnormally high while smoking, begin to return to normal.
- Within a few hours, the level of carbon monoxide in the blood begins to decline. (Carbon monoxide reduces the blood’s ability to carry oxygen.)
- Within a few weeks, people who quit smoking have improved circulation, produce less phlegm, and don’t cough or wheeze as often.
- Within several months of quitting, people can expect substantial improvements in lung function.
- Within a few years of quitting, people will have lower risks of cancer, heart disease, and other chronic diseases than if they had continued to smoke.
- In addition, people who quit smoking will have an improved sense of smell, and food will taste better.
What are the long-term benefits of quitting smoking?
Quitting smoking reduces the risk of cancer and many other diseases, such as heart disease and COPD, caused by smoking.
Data from the U.S. National Health Interview Survey show that people who quit smoking, regardless of their age, are less likely to die from smoking-related illness than those who continue to smoke. Smokers who quit before age 40 reduced their chance of dying prematurely from smoking-related diseases by about 90 percent, and those who quit by age 45-54 reduced their chance of dying prematurely by about two-thirds.
People who quit smoking, regardless of their age, have substantial gains in life expectancy compared with those who continue to smoke. Those who quit between the ages of 25 and 34 years lived about 10 years longer; those who quit between ages 35 and 44 lived about 9 years longer; those who quit between ages 45 and 54 lived about 6 years longer; and those who quit between ages 55 and 64 lived about 4 years longer.
Does quitting smoking lower the risk of cancer?
Yes. Quitting smoking reduces the risk of developing and dying from cancer. Although it is never too late to get a benefit from quitting, the benefit is strongest among those who quit at a younger age.
The risk of premature death and the chance of developing cancer from smoking depend on many factors, including the number of years a person smokes, the number of cigarettes he or she smokes per day, the age at which he or she began smoking, and whether or not he or she was already ill at the time of quitting. For people who have already developed cancer, quitting smoking reduces the risk of developing a second cancer.
Should someone already diagnosed with cancer bother to quit smoking?
Yes. Cigarette smoking has a profound adverse impact on health outcomes in cancer patients. For patients with some cancers, quitting smoking at the time of diagnosis may reduce the risk of dying by 30 percent to 40 percent. For those having surgery, chemotherapy, or other treatments, quitting smoking helps improve the body’s ability to heal and respond to therapy. It also lowers the risk of pneumonia and respiratory failure. Moreover, quitting smoking may lower the risk of the cancer returning, of dying from the cancer, of a second cancer developing, and of dying from other causes.