Scientists still have a lot to learn about what causes cancer—which is actually not one, but many diseases—and how to prevent it. However, there is good evidence that these lifestyle changes can dramatically decrease the risk. And don’t forget to get recommended screening tests, some of which (like colonoscopy) can actually prevent cancer.

Healthy Eating - Masterfile

Follow these top 12 ways to prevent cancer:

1. Don’t Smoke or Use Any Tobacco Product

Cigarette smoking causes lung cancer, of course, but also cancers of the esophagus, larynx, mouth, throat, kidney, bladder, pancreas, stomach and cervix. Other tobacco products (smokeless tobacco, cigars, pipes) also increase cancer risk. Smoking is the leading cause of premature, preventable death in this country and in much of the world. Each year, about 79,000 men and 56,000 women in the U.S. die from lung cancer caused by cigarette smoking. In addition, about 3,000 lung cancer deaths occur each year among adult nonsmokers in the U.S. as a result of secondhand smoke.

If you smoke or use other tobacco products, quitting is by far the most important way to prevent cancer and protect your overall health. It is never too late to quit.

2. Maintain a Healthy Weight

Studies suggest that obesity contributes to about 14 percent of the cancer deaths in American men and 20 percent of those in women. Obese people are at greater risk of developing colorectal cancer, as well as esophageal adenocarcinoma, gallbladder and liver cancer, leukemia, multiple myeloma and non-Hodgkin’s lymphoma. In addition, obese postmenopausal women are at increased risk for breast and uterine cancer.

Precisely why body fat increases cancer risk isn’t fully understood. There is evidence that fat cells increase blood levels of a number of hormones that can fuel the growth of certain types of cancers, at least in lab studies. Obesity is also linked to chronic inflammation in the body, which can contribute to cancer development.

3. Exercise

Physical activity plays an important role in cancer prevention—and not just because it can help you control your weight. Exercise may also reduce cancer risk by lowering hormones and cellular growth factors, improving insulin resistance and, when done in moderation, enhancing the immune system.

Exercise has also been found to improve the prognosis and/or well-being of people already diagnosed with cancer. The best evidence of potential benefit concerns colon cancer. The effect on breast cancer risk has also been studied extensively, with mostly positive results. For prostate, lung and endometrial cancers, research on cancer prevention has been promising, though less consistent.

Of course, people who exercise tend to do other healthy things, which makes it hard to tease apart whether it’s the exercise, healthy lifestyle or the combination of the two that decreases cancer risk. It’s also not clear what kind of exercise is most beneficial—and whether you need to start young and exercise your whole life to reduce cancer risk or if becoming active later is beneficial, too.

4. Eat a Healthy Diet

Among the top ways to prevent cancer, there’s much debate about the specifics of what constitutes an "anti-cancer" diet, but the basics are pretty simple. Eat at least five (better yet, nine) servings of a variety of vegetables and fruits every day. Limit your intake of red meat and pork, especially processed meats. Choose whole grains over refined-grain products. Avoid salty and salt-preserved foods. In simple terms, you should be eating a high-fiber diet that is as close to vegetarian as possible.

Don’t be confused by some widely publicized studies that suggested that fruits and vegetables do little or nothing to reduce cancer risk. There are many types of fruits and vegetables, as well as different types of cancer, so specific connections may be hard to spot in studies that lump everything together. It’s also possible that your genes may determine if, and how much, certain fruits and vegetables protect your body against various cancers, or that what you ate when you were young, rather than what you eat now, plays a larger role in preventing or promoting cancer.

5. Drink Less Alcohol

Alcoholic beverages increase the risk of various cancers, and the more you drink, the greater the risk. The evidence is strongest for cancers of the esophagus, mouth, throat and larynx. You are at even greater risk if you drink and smoke. Research also suggests that alcohol increases the risk of liver, colorectal and breast cancer.

How should you weigh this risk in light of the advice to have a drink a day for your heart? Remember that there are a number of ways to reduce your risk of heart disease that also reduce cancer risk: notably exercise, not smoking and eating a healthy diet. That is, you don’t need to drink alcohol to protect your heart. In particular, if you know you are at high risk for breast cancer, or if you’ve had breast cancer, you should consider not drinking or drink only occasionally.

If you do drink, drink in moderation. For women, that means no more than one drink a day; for men it’s one or two drinks. And if you’re over 65, you should drink even less than that.

6. Limit High-Heat Cooking

Cooking high-protein foods such as meat, fish and poultry at high temperatures over coals or flames creates chemicals called heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs), which are believed to promote cancer risk. The same is true of pan-frying such foods on the stove, or any high-heat cooking method. Studies have shown that very high levels of HCAs and PAHs can cause many different types of cancer in rodents. In addition, observational studies have found that people who eat lots of fried or barbecued meat and other charred foods are at increased risk for colorectal, pancreatic and prostate cancer.

If you do cook at high temperatures, precooking the meat in the microwave for a few minutes before putting it on the grill and turning it frequently while it’s cooking to prevent charring will help reduce the levels of HCAs and PAHs.

7. Limit Sun Exposure

It’s estimated that ultraviolet radiation from the sun or tanning beds is responsible for the great majority of the two million cases of skin cancer diagnosed in the U.S. each year. Most of these skin cancer are basal cell carcinomas, which rarely spread. Many others are squamous cell carcinomas, which often begin as a type of skin lesion called actinic keratoses. In addition, about two-thirds of all cases of melanoma, the most dangerous skin cancer, can be attributed to sun exposure.

Sunscreen reduces the risk of most skin cancers—if it’s used properly. One problem is that most of us don’t use enough sunscreen and don’t reapply it as often as necessary. Moreover, even if you use it properly, sunscreen shouldn’t give you a false sense of security, since no product blocks 100 percent of all damaging rays.

8. Limit Radiation from Medical Imaging Tests

Experts have become increasingly concerned about the overuse of many types of medical scans in the U.S., largely because of the cumulative exposure to radiation. Americans, on average, are exposed to six times more radiation from medical imaging, especially from CT scans, than they were three decades ago. Each year, about 10 percent of Americans undergo CT scans, and the number is rising. Such scans now account for half of our total radiation exposure. The risk from a single CT scan, when appropriately done, is minuscule, but radiation exposures add up over a lifetime.

Make sure that imaging tests are done only when there is a clear benefit that outweighs the risks—and that the minimal level of radiation will be used. Before undergoing a diagnostic scan, ask if the test is really necessary and whether it really improves your health care. Also ask if there is a nonradiation alternative, such as ultrasound or MRI, that’s equally good. Before having any imaging scan, discuss the pros and cons with your doctor.

9. Test Your Home for Radon

A colorless, odorless radioactive gas, radon is formed during the natural breakdown of uranium in soil, rock and water. Exposure to radon is the second leading cause of lung cancer, and is related to about 15,000 to 20,000 lung cancer deaths in the U.S. each year. People who smoke and are also exposed to radon have the highest risk of developing lung cancer.

Radon can get into your home through cracks and holes in floors, walls or foundations. It also can be released from building material and from well water. Testing is the only way to know if your home has high radon levels. To find out about radon testing, call the National Radon Hotline at 800–55–RADON or go to

10. Test Your Water for Arsenic

Arsenic is a tasteless, odorless chemical element found naturally in rocks, soil, water and air. When arsenic is combined with oxygen, iron, chlorine and sulfur it creates an inorganic compound that can be found in certain building materials and contaminated water. Exposure to high levels of this type of inorganic arsenic has been linked to cancers of the bladder, colon, kidney, liver, lung and skin.

If your water comes from a public drinking water system, you probably don’t need to worry about arsenic. The Environmental Protection Agency (EPA) requires public drinking water systems to test for arsenic and make sure that levels do not exceed 10 parts per billion. Rural communities tend to have higher levels of arsenic in their water. If you live in a rural area and get your water from a private source, like a well, you should have the arsenic level in your water tested. If the level is high, you should use bottled water. Water filters that you put on a faucet do not remove arsenic. To learn more about testing your water for arsenic, contact the EPA’s Safe Drinking Water Hotline at 800-426-4791.

11. Decrease Your Workplace Exposure to Carcinogens

Occupational exposures to carcinogens are responsible for an estimated 40,000 new cancer cases and 20,000 cancer deaths in the U.S. each year. Bartenders and waitstaff, for instance, are often exposed to secondhand smoke (except in localities with smoking bans). Workers in chemical plants, gasoline-related industries and the printing business may be exposed to benzene, a chemical that has been linked to leukemia and Hodgkin’s lymphoma. Workers in the funeral industry and in hair and nail salons may be exposed to formaldehyde.

The National Institute for Occupational Safety and Health has created a pocket guide to chemical hazards, which discusses recommended exposure limits, exposure routes and personal protection and sanitation recommendations. You can download the guide at If you think your job may expose you to known or potential carcinogens, you should check the government regulations for your workplace to be sure your employer is following them.

12. Limit Your Exposure to Air Pollution—Outdoors and Indoors

About one in every 28,000 Americans may develop cancer as a result of outdoor air pollutants, according to EPA estimates. However, more than 2 million people live in areas where the lifetime cancer risk is much higher, largely because of nearby industries that emit carcinogens. provides an air-quality index that reports daily air quality throughout the country, with categories ranging from good to hazardous. You can help keep the air cleaner by carpooling or using public transportation, reducing or eliminating fireplace and wood stove use, avoiding the use of gas-powered lawn and garden equipment, and not burning leaves, trash or other materials.

If the air quality is bad, you’re better off going to the gym or spending time indoors than heading out for a walk or run. You can also reduce your exposure to outdoor air pollutants by limiting your time outside during peak traffic and by choosing walking routes that go along side streets rather than busy roads.

But keep in mind, the air you breathe at home is often more heavily polluted than the air outside. Tobacco smoke is by far the worst pollutant. Cleaning products, mothballs and manufactured wood products are other items that can release indoor volatile organic compounds (VOCs), some of which are known or suspected carcinogens. Plywood, particle board and other manufactured wood products can release formaldehyde.

Besides limiting your exposure to these sources, open windows and doors as often as possible. Use venting systems in bathrooms, kitchens and any room with a fireplace, woodstove or range. Don’t use incense, air fresheners or scented candles. Use insecticides sparingly and avoid mothballs.


This information was adapted from The University of California, Berkeley Wellness Report: Preventing Cancer: Strategies to Reduce Your Risk, by Dr. John Swartzberg and Dr. Jeffrey Wolf. Published: 2011

Publication Review By: the Editorial Staff at

Published: 08 Dec 2011

Last Modified: 26 Oct 2015