Both genes and environment play a role in carcinogenesis, when normal cells turn into cancerous ones. Although you cannot change your genes, you can control many environmental risk factors. Estimates suggest that as many as 45 per cent of cancers might be avoided by removing known environmental hazards. You can take steps to prevent cancer and its complications.
Tobacco alone is responsible for a significant number of cancers – 30 per cent in men and 20 per cent in women. Smoking is thought to cause 22 per cent of all deaths, since it is also the leading risk factor for cardiovascular and respiratory disease.
Cigarettes are the most common form of tobacco. Other forms of tobacco exposure, including cigars, pipes, smokeless tobacco and second-hand smoke, can also cause cancer.
Tobacco use is linked with cancer in many parts of the body – most notably the lungs, bladder, head and neck. Using tobacco encourages cancer, putting carcinogens (cancer-causing agents) directly into the body. This inflames the body and interferes with its defences against cancer. Avoiding all tobacco products and second-hand smoke is an important part of preventing cancer.
Cancers linked to tobacco can be fought in two ways – by stopping people from starting to smoke and helping them stop. This may sound simple but is difficult. Despite being aware of the dangers of smoking, kids still want to be part of the crowd. A strong support system at school and home helps to resist peer pressure.
If you smoke, quitting is the best thing you can do for your health. It is certainly not easy, and often takes time. Many stop smoking aids are available. Your family doctor can help choose the right one and support you during the quitting process. The average smoker loses 13 years of life as a result of smoking. You have the power to take these years back!
Losing extra weight is another factor in cancer prevention. Studies show that the rates of many cancers, including breast and colorectal cancers, are higher in those with a higher body mass index (BMI). BMI can be calculated by dividing your weight in kilograms by the square of your height in meters. Many easy-to-use on-line calculators are also available. A BMI of 20 to 24.9 is considered best.
Physical activity also lowers the risk of cancer, even in overweight people. Of course, the benefits of an active lifestyle extend beyond avoiding cancer. Exercise helps prevent serious illnesses like heart disease and stroke, while improving mood and fighting depression.
Infections may cause as many as 17 per cent of new cancers, so avoiding them is key. Most are passed through blood and body fluids. Take precautions when engaging in an activity where passing these fluids is possible. This includes needle use, getting tattoos, and sexual activity.
Perhaps the most widely known of these infections are the human papillomavirus (HPV), hepatitis B virus (HBV), and human immunodeficiency virus (HIV). HPV is a sexually transmitted virus shown to cause cancer of the cervix, as well as anus and penis cancers. It is also one of the most common sexually transmitted diseases. School-age girls can now be vaccinated against HPV to protect them from cancer of the cervix.
The hepatitis B virus infects the liver and can lead to liver failure and cancer. It is passed though exposure to body fluids. All children are vaccinated against HBV in school, preventing complications from this infection.
However, there is no vaccine for HIV. This infection is linked to the cancers Kaposi’s sarcoma and non-Hodgkin’s lymphoma. Avoiding exposure is the best defence against HIV.
Sun exposure is the main cause of skin cancer. In the body, DNA carries genetic information in cells. Ultraviolet rays from the sun damage DNA, changing genes to promote the development of cancer. It appears that the risk accumulates. Exposure early in life, and spending more time in the sun, adds up to increase the risk of skin cancer. You can reduce UV exposure by applying sunscreen, wearing hats and clothing with long sleeves and avoiding the sun when the UV index is three or higher. UV exposure peaks during the hours between 1:00 and 4:00 pm.
Tanning beds are another source of harmful UV rays. Many studies show a link between sunlamp use and melanoma, the most serious form of skin cancer. One study showed that tanning beds increase the risk by 75 per cent for younger people. Avoid using tanning salons, especially if you are not yet 35.
Alcohol use is linked to cancer. Women who have one drink a day are nine per cent more likely to develop breast cancer. However, taking a folic acid supplement may reduce the risk. Women who drink alcohol regularly should consider a supplement or multivitamin with folate.
Cancers of the oral cavity, pharynx, larynx, and esophagus are also tied to alcohol use. The risk of liver cancer increases in heavy drinkers or those who have another liver disease like viral hepatitis.
In spite of these risks, using alcohol in moderation may have some health benefits. It appears to lower the risk of cardiovascular disease. Even so, men should limit alcohol intake to 14 drinks per week and women to seven. Those with other illnesses may have a lower recommended limit.
A healthy diet protects against cancer, while a poor diet encourages it. Fruits and vegetables appear to defend against colorectal cancer. Tomatoes in particular seem to lower the risk of prostate cancer, while eating too much red meat promotes it. A diet high in animal fat may also contribute to prostate cancer. However, low-fat dairy products may protect women from breast cancer before menopause.
The principles of eating to prevent cancer are the same as the general principles of a healthy diet. Canada’s Food Guide is an excellent resource for more information.
If you have a well-balanced diet, there is little value in taking dietary supplements. Many studies examining the effects of supplements have not clearly linked them to preventing cancer. (Multivitamins, vitamin C, vitamin E, calcium and vitamin D, selenium, and folate have all been studied.) This result may reflect that study participants are from a well-nourished western population.
The only exception is alcohol. Alcohol interferes with the availability of folate and may increase the risk of colon and breast cancers. Taking a folate supplement may benefit those who drink a significant amount of alcohol.
Canada’s Food Guide
Canada’s Physical Activity Guide
Diseases and Conditions, Cancer, Health Canadawww.hc-sc.ca
Canadian Cancer Society (also has a Smoker’s Helpline)
The Lung Association - How to Quit Smoking
Go to the Protect your Lungs menu and select Smoking and Tobacco
HPV Prevention and Vaccine
Hep B Facts
Alberta Alcohol and Drug Abuse Commission
Cancer screening programs use various medical tests and procedures to find cancer at a relatively early stage. As a result, cancers that might be missed are caught early and treated. In many cases, there might even be a cure. Medical research repeatedly shows that screening saves lives.
Routine cancer screening is recommended for all people. This process includes screening for cervical, breast, colorectal, and prostate cancers. Screening generally begins in young adulthood for cervical cancer, and at age fifty for other cancers. However, those at high risk thanks to family history and other disease conditions may need to be screened earlier. Your family doctor can discuss appropriate screening options.
Cancer causes nearly 30 per cent of deaths in our society. The need for prevention is clear. Prevention does not require much beyond living in a healthy way (see sidebar). Making wise choices not only reduces the risk of cancer, but improves general health and prevents other illnesses.