By Miriam Komaromy, MD

Reviewed by Peggy Conrad, MS, CGC and Jonathan Terdiman, MD
Last updated March 3, 2001

Although there are many risk factors for colon cancer that you cannot control, such as genetic predisposition and increasing age, there are also some risk factors that you can change. The majority of these involve lifestyle, which means that by simply modifying certain behaviors, you may be able to decrease your risk of colon cancer.

Lifestyle Factors That Affect Risk

If you take look at the table below, you'll see that there are a number of nongenetic factors that scientists believe may affect your risk — either positively or negatively — for developing colon cancer.

Nongenetic Factors That May REDUCE Your Risk for Colon Cancer	Nongenetic Factors That May INCREASE Your Risk for Colon Cancer
Eating vegetables	Smoking
Adequate calcium intake	Eating meat
Eating fiber	Alcohol consumption
Non-steroidal anti-inflammatory drugs	Eating animal fat
Physical activity	Obesity
Postmenopausal estrogen use	Increasing Age
	History of inflammatory bowel disease (NOT irritable bowel disease)

Researchers have not yet established whether making lifestyle changes does have a major impact on colon cancer risk.

Although these factors could be promising areas for you to take control over your colon cancer risk, researchers have not yet established whether making changes along these lines does indeed have a major impact. Furthermore, researchers don't know what effect altering such factors have in people with a hereditary colon cancer syndrome. Because of this uncertainty, none of the major colon cancer prevention guidelines take these factors into consideration. However, many changes associated with decreased colon cancer risk (such as eating less red meat or consuming more vegetables) contribute to a more healthy lifestyle overall — thus, the fact that they may well diminish colon cancer risk is certainly an added benefit. (For recent news about how lifestyle factors relate to colon cancer risk, see Related News below.)

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Calcium

The data on calcium intake and colon cancer (though somewhat inconsistent) suggests that you can decrease your risk of developing the disease by increasing your calcium intake. A recent study linked calcium supplements (three grams per day) with the decreased development of colon polyps.

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Nonsteroidal Anti-Inflammatory Drugs

Many studies have shown that nonsteroidal anti-inflammatory drugs — which includes aspirin, ibuprofen, and sulindac (among others) — reduces a person's risk of developing colon cancer. One recent study found that non-aspirin NSAIDs reduced the risk of developing colon cancer by half. In this study, people who took high doses of aspirin also lowered their risk, but low doses of aspirin had no effect on colon cancer risk. The protective effect of taking NSAIDs became evident within six months of beginning to take the drugs, and disappeared one year after stopping. However, this study and the ones that came before it are not considered conclusive proof that NSAIDs prevent colon cancer. In order to show this relationship conclusively, researchers must take a big group of people, give some of them these drugs and the others none, and then wait to see whether differences in cancer rates develop. Thus, if you are considering taking NSAIDs to reduce your risk of colon cancer, you should talk with your doctor first because they can sometimes cause serious side effects such as gastrointestinal bleeding.

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Postmenopausal Estrogen Use

Some data suggests that using postmenopausal estrogens can also reduce the risk of developing colon cancer. However, scientists still need to collect more data to determine whether the effect of such drugs is strong enough to recommend that people use them for this purpose. If you are considering taking estrogen to reduce your risk of colon cancer, you should talk with your doctor first because it can sometimes cause serious side effects, such as uterine cancer and blood clots. (For recent news about the affect of hormone replacement therapy on colon cancer risk, see Related News below.)

Fiber

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Related News

In order to view these articles you will need to have a MyGeneticHealth account. If you are not already a member, selecting the article will automatically take you to a page where you can sign up. Younger women on HRT may be at risk for colon polyp recurrence Oral contraceptives reduce colorectal cancer risk Excess body weight increases risk of some cancers Use of some painkillers may cut colon cancer risk Gene discovery links smoking and colorectal cancer Smoking ups gene defect in colon cancer Obesity linked to increased risk of colon cancer mortality, especially in men Wine drinking may reduce colon cancer risk Garlic: A clove a day may keep cancer at bay

References

Baron, J. et al. (1999). Calcium supplements for the prevention of colorectal adenomas. Calcium Polyp Prevention Study Group. New England Journal of Medicine 340(2): 101-7.

Gann, P. et al. (1993). Low-dose aspirin and incidence of colorectal tumors in a randomized trial. Journal of the National Cancer Institute 85(15): 1220-4.