Colorectal Cancer

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Causes, Risk Factors, and Prevention TOPICS

Can colorectal cancer be prevented?

There is no sure way to prevent colorectal cancer. But there are things you can do that might help lower your risk, such as changing the risk factors that you can control.

Colorectal cancer screening

Screening is the process of looking for cancer or pre-cancer in people who have no symptoms of the disease. Regular colorectal cancer screening is one of the most powerful weapons for preventing colorectal cancer.

From the time the first abnormal cells start to grow into polyps, it usually takes about 10 to 15 years for them to develop into colorectal cancer. With regular screening, most polyps can be found and removed before they have the chance to turn into cancer. Screening can also find colorectal cancer early, when it is highly curable.

Screening is recommended starting at age 50 for people who are not at increased risk of colorectal cancer. There are several different screening options available. People at higher risk, such as those with a strong family history of colorectal cancer, might benefit from starting screening at a younger age.

If you have a strong family history of colorectal polyps or cancer, talk with your doctor about your risk. You might benefit from genetic counseling to review your family medical tree to see how likely it is that you have a family cancer syndrome.

For more about screening (including the American Cancer Society guidelines for the early detection of colorectal cancer) and genetic counseling and testing, see Colorectal Cancer Prevention and Early Detection.

Body weight, physical activity, and diet

At this time, the best advice about diet and activity to possibly reduce your risk of colorectal cancer is to:

    · Avoid obesity and weight gain around the midsection.

    · Increase the intensity and amount of your physical activity.

    · Limit red and processed meats.

    · Eat more vegetables and fruits.

    · Get the recommended levels of calcium and vitamin D (see below).

    · Avoid excess alcohol.

Weight: Being overweight or obese increases the risk of colorectal cancer in both men and women, but the link seems to be stronger in men. Having more belly fat (that is, a larger waistline) has also been linked to colorectal cancer.

Physical activity: Increasing your level of activity lowers your risk of colorectal cancer and polyps. Regular moderate activity (doing things that make you breathe as hard as you would during a brisk walk) lowers the risk, but vigorous activity might have an even greater benefit.

Diet: Overall, diets that are high in vegetables, fruits, and whole grains (and low in red and processed meats) have been linked with lower colorectal cancer risk, although it’s not exactly clear which factors are important. Many studies have found a link between red meats (beef, pork, and lamb) or processed meats (such as hot dogs, sausage, and lunch meats) and increased colorectal cancer risk.

In recent years, some large studies have suggested that fiber in the diet, especially from whole grains, may lower colorectal cancer risk. Research in this area is still under way.

Alcohol: Several studies have found a higher risk of colorectal cancer with increased alcohol intake, especially among men.

For more about diet and physical activity, see the American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention.

Not smoking

Long-term smoking is linked to an increased risk of colorectal cancer, as well as many other cancers and health problems. If you smoke and would like help quitting, see our Guide to Quitting Smoking, or call the American Cancer Society at 1-800-227-2345.

Vitamins, calcium, and magnesium

Some studies suggest that taking a daily multi-vitamin containing folic acid, or folate, may lower colorectal cancer risk, but not all studies have found this. In fact, some studies have hinted that folic acid might help existing tumors grow. More research is needed in this area.

Some studies have suggested that vitamin D, which you can get from sun exposure, in certain foods, or in a vitamin pill, might lower colorectal cancer risk. Because of concerns that excess sun exposure can cause skin cancer, most experts do not recommend this as a way to lower colorectal cancer risk at this time.

Other studies suggest that increasing calcium intake may lower colorectal cancer risk. Calcium is important for a number of health reasons aside from possible effects on cancer risk. But because of the possible increased risk of prostate cancer in men with high calcium intake, the American Cancer Society does not recommend increasing calcium intake specifically to try to lower cancer risk.

Calcium and vitamin D might work together to reduce colorectal cancer risk, as vitamin D aids in the body’s absorption of calcium. Still, not all studies have found that supplements of these nutrients reduce risk.

A few studies have found a possible link between a diet that is high in magnesium and reduced colorectal cancer risk, especially among women. More research is needed to determine if this link exists.

You should talk with your doctor or a member of your health care team if you want to know more about taking these supplements.

Non-steroidal anti-inflammatory drugs (NSAIDs)

Many studies have found that people who regularly take aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Motrin, Advil) and naproxen (Aleve), have a lower risk of colorectal cancer and polyps. Most of these studies looked at people who took these medicines for reasons such as to treat arthritis or prevent heart attacks. Other, stronger studies have provided evidence that aspirin can help prevent the growth of polyps in people who were previously treated for early stages of colorectal cancer or who had polyps removed.

But aspirin and other NSAIDs can cause serious or even life-threatening side effects such as bleeding from stomach irritation, which may outweigh the benefits of these medicines for the general public. For this reason, most experts don’t recommend taking NSAIDs just to lower colorectal cancer risk if you are someone at average risk. However, the other possible benefits of aspirin, such as lowering the risk of some types of heart disease, might outweigh the risks in certain groups of people, such as those at higher risk for heart disease.

The value of aspirin and similar drugs for people at increased colorectal cancer risk is being studied. Celecoxib (Celebrex) has been approved by the US Food and Drug Administration (FDA) for reducing polyps in people with familial adenomatous polyposis (FAP). This drug may cause less bleeding in the stomach than other NSAIDs, but it may increase the risk of heart attacks and strokes.

Aspirin or other NSAIDs can have serious side effects, so check with your doctor before starting any of them on a regular basis.

Hormone replacement therapy for women

Taking estrogen and progesterone after menopause (sometimes called menopausal hormone therapy or combined hormone replacement therapy) may reduce a woman’s risk of developing colorectal cancer, but cancers found in women taking these hormones after menopause may be at a more advanced stage.

Taking estrogen and progesterone after menopause also lowers the risk of osteoporosis (bone thinning). But it can also increase a woman’s risk of heart disease, blood clots, and cancers of the breast and lung.

If you are considering using menopausal hormone therapy, be sure to discuss the pros and cons with your doctor.

Last Medical Review: 10/15/2015
Last Revised: 01/20/2016