Chemoprevention Targets Colorectal Cancer

Clinical trials aimed at finding ways to prevent cancer have been around for nearly two decades, but they have grown significantly in recent years, with many expanding into comprehensive programs.

Known as chemoprevention studies, these trials involve the use of drugs, vitamins, diet, hormone therapy or other agents in an effort to reduce the risk, development or recurrence of cancer.

Like many centers, M. D. Anderson has developed chemoprevention programs involving a variety of cancer types. One of the most active programs was created within the Department of Gastrointestinal Medicine & Nutrition to target colorectal cancer.

Disease focus

Colorectal cancer, which receives increasing attention every March during National Colorectal Cancer Awareness Month, is the third-most common cancer in both men and women in the U.S., according to the American Cancer Society (ACS).

Incidence rates have declined 3% from 1998 to 2000, with research suggesting that the decrease is due in part to increased screenings and the preventive removal of pre-cancerous polyps, the ACS says.

"The biggest impact we are going to have on cancer is early detection and prevention," says Robert Bresalier, M.D., professor and chair of the Department of Gastrointestinal Medicine & Nutrition. "I think prevention has now come of age. We've had hints for a long time that prevention should work, but finally we're getting hard data through clinical trials that we can have an impact in cancer survival, and that's exciting. There's no magic bullet - so clearly each study alone is not going to be the answer."

The colorectal chemoprevention program studies include:

Aberrant Crypt Foci (ACF) study

Aberrant Crypt Foci (ACF) are tiny lesions found in the lining of the colon and rectum. Studies have shown that some ACF may lead to polyps (colorectal adenomas), noninvasive lesions with genetic abnormalities that have the ability to develop into cancer.

Researchers are comparing three medications to a placebo (sugar pill):

• Aspirin
• Sulindac, a non-steroidal anti-inflammatory drug (NSAID) used to treat arthritis
• Ursodiol, a drug used to prevent or dissolve cholesterol gallstones

All three medications are approved by the Food and Drug Administration (FDA) but are considered investigational in this trial.

The ACF study has the following goals:

• To find out if the size and number of ACF vary between people with a history of polyps or cancer in their colon or rectum, compared to people who have never had polyps or cancer
• To determine the distribution of ACF in the colon and rectum
• To determine if the medications prevent ACF from developing, or if they cause existing ACF to go away

The study is open to:

• Men and women over age 40 who have been diagnosed with colon polyps or colon cancer
• People meeting those requirements who are not currently receiving chemotherapy or radiation

Study participants will not be able to take aspirin or products that contain aspirin while they are involved in this study.

Vitamin D and calcium supplement study

M. D. Anderson is one of nine institutions conducting a clinical trial to find out if taking a combination of vitamin D and calcium supplements may prevent the development of polyps.

Study participants are people who have already had polyps removed and are considered to be at average risk for colon cancer development.

Familial adenomatous polyposis (FAP) studies

M. D. Anderson is conducting two different chemoprevention studies involving familial adenomatous polyposis (FAP). One involves adults; and the other focuses on children.

People diagnosed with FAP will develop hundreds to thousands of polyps throughout their gastrointestinal tract beginning at a young age, usually as a teenager or young adult. If not treated, 93% of them will develop colon cancer by age 50.

Participants in the studies must have:

• A confirmed diagnosis of FAP
• All or part of their colons remaining
• At least five small polyps in the colon and/or rectum

They also must agree to take the study drugs and be willing to undergo two colonoscopies and one EGD (an examination of the stomach and a segment of the small intestines).

Psycho-social study

The psychological effects of cancer is the subject of a trial led by principal investigator Susan Peterson, M. D., assistant professor in M. D. Anderson's Department of Behavioral Science. The study involves completing psychosocial assessments of both children and adults with FAP.

Not only is FAP physically challenging, it also can have an impact on many other aspects of life. Peterson and her colleagues are looking at how this genetic illness affects family dynamics and social interactions. Findings from this research will provide unique insight into how people cope with a genetic illness.

Research continues

The ultimate goal of chemoprevention for all cancers is to reduce incidences of the disease. More than 1.36 million people are expected to be diagnosed with cancer in the United States in 2004, according to the ACS. Of that total, more than 150,000 are expected to be colorectal cancer.

For more information, please contact the M. D. Anderson Information Line at 1-800-392-1611, option 3.