Opportunities to prevent colon cancer

In the United States, colon and rectal cancers (often referred to together as colorectal cancer) are common in both men and women — more than 130,000 new cases are expected and about 56,300 people will die from the disease this year. There is increasing evidence that colorectal cancers can be prevented and ongoing research is looking for new ways to prevent the disease.

On NBC's "Today" show, Dr. Ernest Hawk discusses some of the actions people can take to help reduce their risk for colon cancer.

EVERYONE’S RISK for colorectal cancer is different, and you should discuss your risk with your doctor. Some of the factors that put people at risk for colorectal cancer include:

Aging (most cases occur in people over age 50)

Personal history of polyps, colorectal cancer, or inflammatory bowel disease

Family history of polyps or colorectal cancer (any family member)

Other factors under study include:

Diets high in fat, calories, protein, meat, and alcohol and low in whole grains, fruits, vegetables, calcium, and folate

Smoking

Sedentary lifestyle

Colorectal cancer results from complex interactions between a person’s own genetic make-up and outside factors. Science has shown that these interactions take years to develop into cancer. In other words, cancer is not simply a single catastrophic event, but the end result of a slow process that takes 10 to 20 years to fully develop. One early stage of colorectal cancer development is an adenomatous polyp, a growth in the colon or rectum. Removing polyps can prevent cancer from forming in that polyp. There are also opportunities for prevention before and after a polyp appears.

PREVENTION OPPORTUNITIES IN EVERYDAY LIVING

Everyday Opportunities

Eat a diet rich in fruits, vegetables, and whole grains and low in fat.

Exercise regularly.

Don’t smoke, or if you do smoke, quit.

Eating lots of fruits, vegetables, and whole grains can have a number of health benefits, and some studies suggest that people who eat such a diet may have a reduced risk of colorectal cancer. In some studies in which we look at people’s diet but do not try to change it, we’ve found evidence that people whose diet gave them more calcium and who get enough selenium or folate tend to have less colorectal cancer. This suggestion prompted a clinical trial in which people who had polyps removed took either a calcium supplement or a placebo (inactive pill). Those who took the calcium supplement had fewer new polyps. More studies are under way to further explore the potential positive effects of calcium, selenium, and folate supplements (see clinical trials, below).

Studies of exercise are remarkably consistent — people who exercise regularly have about half the risk for colorectal cancer as those who are inactive. The details are uncertain — we don’t know exactly what kind or what level of exercise is needed to prevent colorectal cancer. But because exercise is so important for overall health, this form of prevention can be pursued without waiting for more information.

Never smoking, or quitting if you do smoke, could help lower colorectal cancer risk, and like exercise, quitting smoking has a wide range of benefits.

PREVENTION OPPORTUNITIES THROUGH SCREENING

Screening Opportunities

Talk to your relatives about colorectal cancer and polyps in your family, so everyone knows the family’s medical history.

Talk to your doctor about your risk of colorectal cancer.

Talk to your doctor about regular screening using fecal occult blood test, sigmoidoscopy, colonoscopy, or double contrast barium enema.

Some studies have shown that people who have adenomatous polyps removed reduce their risk of colorectal cancer by as much as 75 percent. But how does a person know they have polyps? The truth is they usually can’t tell — even full-blown colorectal cancer doesn’t necessarily cause symptoms. Therefore, screening for colorectal cancer in healthy people is a prevention opportunity to discuss with your doctor. Screening may help find polyps which can be removed, and find early cancer when it is easiest to treat.

In reality, there is more similarity between a polyp and cancer than between a polyp and healthy tissues. Like high blood pressure and elevated cholesterol, which indicate increased risk for heart disease, prompting action by patients and physicians; polyps signal an increased risk for cancer and the need for preventive action.

People at high risk of colorectal cancer may need earlier and more intense screening than others, but even people at average risk should consider being screened. Talk to your doctor about your level of risk and what type of screening is most appropriate.

PREVENTION OPPORTUNITIES THROUGH CLINICAL TRIALS

Clinical trials opportunities

If you are at increased risk of colorectal cancer,consider participating in clinical trials of new prevention agents.

Find out about clinical trials by calling the National Cancer Institute’s Cancer Information Service at 1-800-4-CANCER or by using the NCI’s web site at http://cancernet.nci.nih.gov

Researchers are studying a number of drugs that may prevent or reverse the cancer process. This very exciting area of research is possible because we are discovering more about what happens as cells become cancerous. The more we know about how cells work, the easier it may one day be to find a drug that blocks changes that lead to cancer.

For instance, we have known for years that people who regularly use aspirin or other pain relievers for conditions like arthritis have fewer polyps and less colorectal cancer. But these drugs can cause bleeding and stomach ulcers, so they are not ideal for preventing cancer in healthy people. Newer aspirin-like drugs that work more selectively have been created to treat arthritis and are now being tested to prevent colorectal polyps and cancer.

In a recent study, one of these new drugs, Celecoxib, reduced the number of polyps in some patients with Familial Adenomatous Polyposis (FAP), a genetic disease in which people develop thousands of polyps beginning in their teens and 20s. The National Cancer Institute and two of its pharmaecutical collaborators, GD Searle and Pfizer, are now studying Celecoxib to see if it has preventive effects in people diagnosed with polyps who do not have FAP. [Choose “colon” as type of cancer, and “prevention” as type of trial to get the Celecoxib trial ] And there are other promising agents being tested in clinical trials, including DFMO, Ursodiol, and other drugs as well as calcium, selenium, and folate supplements.

Clinical trials are designed to answer important medical questions and help us learn more about cancer prevention. The promise of cancer prevention can only be realized through greater patient participation in clinical prevention trials. Indeed, we are all indebted to people who have participated in clinical trials in the past — their contributions have been the foundation for all current recommendations for cancer prevention. Participating in clinical trials may benefit you, your family, and friends; and ultimately will guide cancer prevention for future generations.

To find out more about colorectal cancer screening, prevention, and treatment, including how to participate in clinical trials:

Visit NCI’s CancerNet web site at: http://cancernet.nci.nih.gov or call NCI’s Cancer Information Service at: 1-800-4-CANCER.

To find out how you can participate in the NCI’s trial of Celecoxib in people with adenomatous polyps who do not have a genetic disease (the APC Trial): Visit: http://cancernet.nci.nih.gov/trialsrch.shtml — choose “colon” as type of cancer and “prevention” as type of trial to get the Celecoxib trial, call NCI’s Cancer Information Service at: 1-800-4-CANCER, or call the APC Trial’s Information Hotline at: 1-888-320-6096.

For more information on colorectal cancer statistics:

Visit the NCI’s SEER program at http://www-seer.ims.nci.nih.gov

Ernest Hawk, MD, MPH is Chief, Gastrointestinal and Other Cancers Research Group, Division of Cancer Prevention at the National Cancer Institute. Dr. Hawk would like to acknowledge the help of Jaye Viner, M.D., Paul Limburg, MD, MPH, and Kara Smigel Croker, MS, RD, of the National Cancer Institute and Caroline Sigman, PhD, of CCS Associates in preparing this article.