Colorectal cancer is the second leading cause of cancer death among men and women in the United States and Canada. Not surprisingly, intense efforts are being made to find out possible ways to prevent it. The number of risk factors is quite bewildering, so here's a listing of things one can do, or things one should try to avoid. Numbered references are given to links at the bottom of the page to pertinent HealthandAge articles, as well as other sites.

The items on the list are classified as:

A. Things you can't change
B. Things you can, and should, change (they are all healthy in other directions, too)
C. Active steps you can take if you think you are at high risk.

A. Things you can't change

1. There are inherited liabilities to colon abnormalities (mostly shown by numerous polyps, which can then become cancerous), that fortunately are rare. ¹ African-Americans and Africans are at increased risk of colon cancer, compared to other races. If either of these apply to you, make sure you reduce your risk of cancer by steps suggested in B and C below.

B. Things you can, and should do

1. Colon cancer can develop in existing colon polyps, which can 'nipped in the bud' during colonoscopy. Schedule your regular large intestine check-ups at the proper intervals.
Beginning at age 50, the American Cancer Society recommends that both men and women at average risk should have one of the following screening regimens:

• Fecal occult blood test every year
• Flexible sigmoidoscopy every five years
• Yearly fecal occult blood test plus flexible sigmoidoscopy every five years (of the first three options, ACS prefers this one)
• Double contrast barium enema every five years
• Colonoscopy every 10 years

A digital rectal exam should be done at the same time as sigmoidoscopy, colonoscopy or double-contrast barium enema. People considered at high risk should undergo more frequent screening of the entire colon, usually with colonoscopy, beginning at a younger age. Talk to your doctor about the schedule best for you.

2. Don't smoke. Cigarette smoking is a known risk factor for colon cancer (as well as for a lot of other conditions)².

3. Check your alcohol intake. Smokers who drink increase their risk for colon cancer, but non-smokers don't seem to increase their risk by drinking alcohol.³ However, excessive alcohol use carries plenty of other risks, whether you smoke or not. And don't worry about coffee -- it doesn't seem to have any effect on the frequency of colon cancer.

4. Get an adequate amount of exercise. Colon cancer is reduced by 40-50% among very active individuals, compared with the least active.⁴

5. Eat a healthy low-fat diet - plenty of green vegetables, fruits, nuts, fish, etc.⁵ Adding some fruits and vegetables to an otherwise produce-poor diet might make a difference in preventing colon cancer. The possible role of fiber is a little controversial -- avoiding supplemental fiber, but not worrying about high fiber in your diet seems a reasonable compromise.

6. Lose any excess weight. The risk of developing colon cancer increases with the degree of being overweight -- at least in women.⁶

7. Is the tomato a fruit or a vegetable? It doesn't matter -- the phytochemicals in tomatoes (especially lycopene) have been shown to reduce the likelihood of prostate cancer, and, to a lesser degree, of colon cancer.⁷ And tomato sauce works just as well.

C. Active steps you can take if you think you are at high risk

If you or your doctors think you are at increased risk of colon cancer, consider some of the following extra steps:

8. Increase your daily intake of calcium to at least 700 mg daily. This could reduce your risk by 40% if you are male; it's not so effective in women, but they need plenty of calcium, anyway, for fighting osteoporosis.⁸

9. Increase your vitamin D intake -- recent findings show that this vitamin helps clear lithocolic acid, a known cancer-causing agent, from the colon.⁹ Don't exceed 600 IU daily, though, as too much may cause side effects.

10. Increase your folic acid intake -- in women, 400 micrograms daily decreases the likelihood of colon cancer.¹⁰

11. Consider taking a non-steroidal anti-inflammatory drug (NSAID) on a regular basis. It's long been known that people taking NSAIDs have a lower likelihood of colon cancer. Recently, it's been shown that one of the 'next generation' NSAIDs, a COX-2 inhibitor (celecoxib), given for 6 months to people with excessive polyp formation in the colon reduced the number of polyps. ¹¹

The great thing about taking steps to avoid colon cancer is that just about all the items are good for you in many other ways. So, now you've got an added incentive to improve your overall health picture!