Painkiller Fails to Prevent Colon Cancer
Sulindac disappoints, but researchers won't give up on NSAIDs
WEDNESDAY, April 3, 2002 (HealthDayNews) -- A pioneering study to see whether an anti-inflammatory drug can prevent colon cancer has produced disappointing results, but researchers say they're not yet convinced that certain painkillers won't ward off the disease.
The idea is that anti-inflammatories can prevent the benign -- noncancerous -- polyps that grow in the colorectal tract from becoming cancerous. Perhaps half of all Americans have such polyps at one time or another, and about 10 percent of those growths will become cancerous.
Laboratory studies have shown that nonsteroidal anti-inflammatory drugs (NSAIDs) or even aspirin, which has anti-inflammatory properties, can prevent that progression. So a group led by Dr. Frank Giardiello, professor of medicine and oncology at the Johns Hopkins Kimmel Cancer Center, decided to test that preventive power in a special group of patients.
These are young people with a genetic mutation called familial adenomatous polyposis (FAP), which causes the growth of hundreds of colorectal polyps and inevitably develops into a hereditary form of colon cancer. Virtually all of these men develop the disease by the age of 30.
The study included 41 FAP patients, aged 8 to 25. Some of them took sulindac, an NSAID now on the market under the brand name of Clinoril, and others were given a placebo.
After four years, 11 of the 20 placebo patients developed polyps while nine of the 21 patients taking sulindac did, says a report in tomorrow's issue of the New England Journal of Medicine.
"We found no statistical difference between the two groups in thwarting the development of polyps or subsequent colon cancer," says Giardiello.
However, he quickly adds "the jury is out on what this study says about NSAIDs and colon cancer." He suspects there could be individual differences in the way that sulindac acts, a feeling based on the study readings of individual levels of prostaglandin, a naturally occurring molecule that causes inflammation.
"We know that NSAIDs inhibit prostaglandin levels," Giardiello says. "We found that those persons who developed polyps had higher levels of prostaglandins, so some patients might metabolize the drug differently."
There are several possible explanations for the result, says Dr. Bernard Levin, vice president for cancer prevention at the M.D. Anderson Cancer Center at the University of Texas.
"The dose may have been inadequate," he says. "The compound itself may be insufficiently powerful to affect a change in people who are genetically predisposed. Perhaps a combination of medications are needed to overcome the genetic drive."
A previous human study produced evidence that sulindac could cause polyps to regress, or grow smaller, Giardiello says. The dosage in the FAP study was based on that trial, he says, but "dosage might be an issue."
Several studies of other NSAIDs and colon cancer are beginning. Giardiello is taking part in one large-scale trial that will use a different NSAID, celecoxib, sold commercially as Celebrex. Celecoxib belongs to a newer family of drugs called cox-2 inhibitors. Like other NSAIDs, they fight pain and inflammation by blocking an enzyme that produces prostaglandins, but they're easier on the stomach.
"Higher doses of the drugs might work, a combination of drugs might work," says Giardiello. "The story is still ongoing."
"I don't think the premise is disproved by this study," says Levin. "What it tells us is that FAP is a very tough nut to crack, and that surgery still is the choice. Obviously, this field is a work in progress. It will take years to tell whether single agents or a combination are effective."
What To Do
Colorectal cancer is curable if detected early, so a colonoscopy to detect polyps when they are not dangerous is recommended. Good diet and physical activity can keep you healthier. If you are at high risk of colon cancer, ask your doctor about participating in a clinical trial of a NSAID.