Most people are aware that smoking is the most common cause of lung cancer, but fewer may know that smoking causes many other types of cancer as well. In fact, according to the U.S. Centers for Disease Control and Prevention (CDC), cigarette smoking either directly causes or contributes to 30% of all cancer-related deaths in the United States—including almost half the deaths from 12 types of cancer.
Risks to smokers
Of the 700–800 naturally occurring chemicals in tobacco smoke, at least 69 can cause cancer. Because these dangerous chemicals travel through the bloodstream to all parts of the body, smoking-related cancer can occur almost anywhere in the body. For example, smoking may double the risk of one type of skin cancer, squamous cell carcinoma.
Head and neck cancers have long been linked with the use of tobacco, especially in the tissues of the mouth and throat that inhaled tobacco smoke has to pass through. According to the CDC, 85% of head and neck cancers are linked to the use of cigarettes or other tobacco products such as cigars or chewing tobacco. And alcohol use multiplies the risk of head and neck cancers in smokers.
Tobacco use is also the principal cause of bladder cancer in the Western world, according to the World Health Organization (WHO). Smoking accounts for 50% of bladder cancers in men and 35% of bladder cancers in women. The WHO estimates that the risk of bladder cancer is two to three times higher for smokers than for nonsmokers, while the U.S. National Cancer Institute estimates that the risk for smokers is four times higher.
Cigarette smoking also increases the risks for acute myeloid leukemia and for cancers of the kidney, pancreas, stomach, uterus, cervix, ovary, colon, and rectum, according to the American Cancer Society.
Risks to nonsmokers
Exposure to secondhand smoke causes cancer, cardiovascular disease, and other diseases as well as premature death in nonsmoking adults and children. The U.S. Environmental Protection Agency, the U.S. National Toxicology Program, the U.S. Surgeon General, and the International Agency for Research on Cancer have all classified secondhand smoke as a known cancer-causing agent.
Secondhand smoke has been proven to cause lung cancer, and some studies suggest that secondhand smoke causes other cancers as well. Specifically, studies have linked secondhand smoke to cancers of the throat in adults and to lymphoma, leukemia, and brain tumors in children.
Benefits of quitting
Many factors contribute to a smoker’s risk of cancer, including the number of years the person has smoked, the number of cigarettes smoked each day, and the age at which the person began smoking.
The good news is that quitting smoking can significantly decrease a smoker’s chances of developing or dying from cancer. For people who already have cancer, quitting smoking reduces the risks of disease recurrence and of developing a second form of cancer. For cancer patients undergoing surgery, chemotherapy, or other treatments, quitting smoking improves the body’s ability to heal and to respond to therapy. Quitting smoking also lowers these patients’ risk of developing pneumonia or respiratory failure.
Smokers of any age can benefit from quitting smoking. Those who quit before their mid-30s can lower their health risks to the same level as those of nonsmokers within a few years. And those who quit smoking at age 50 years reduce their risk of dying prematurely by 50%. Studies have also shown that even people who quit smoking at 60 years or older live longer than those who continue to smoke.
It takes a few years after quitting for ex-smokers’ cancer risk to decline, but the benefit increases the longer a person does not smoke. There are also immediate health benefits to quitting smoking, such as improvements in lung function, a lowering of blood pressure and heart rate, improved circulation, and less coughing.
For smokers in almost any age group or health condition, stopping smoking has major health benefits.
For more information, talk to your physician, visit MD Anderson’s Tobacco Treatment Program at www.mdanderson.org/quitnow, or call 713-792-QUIT.
OncoLog, November-December 2017, Volume 62, Issue 11-12