Celebrex Might Protect Against Colon Cancer

Lowered incidence of precancerous lesions found in two studies

MONDAY, April 3, 2006 (HealthDay News) -- More evidence is indicating that cox-2 inhibitors like Celebrex could prevent precancerous lesions in the colon.

This suggests that the controversial drugs may also have a role to play in preventing colorectal cancer, at least in high-risk individuals.

That's the conclusion of two studies being presented Monday at the American Association for Cancer Research annual meeting, in Washington, D.C.

The results were not unexpected, said an outside expert.

"We assumed that cox-2s would work from what we know about them," said Dr. David E. Beck, chairman of the department of colon and rectal surgery at the Ochsner Clinic Foundation in New Orleans. "This confirms what we thought."

But with the controversy surrounding the cardiovascular risks of these anti-inflammatory drugs, the findings are somewhat muted.

"It's interesting data," Beck continued. "With the question of the risks of cox-2s, the impact is a lot less had that not been an issue. If people still thought they were terribly safe, it would be a much bigger deal. It's interesting. It's somewhat expected. I don't think it's going to change our practice too much."

Cox-2 inhibitors such as Celebrex (celecoxib) were originally developed because they were safer on the stomach than existing pain relievers. Celebrex is the only cox-2 inhibitor left on the market since Vioxx and Bextra were withdrawn, following reports of heightened cardiovascular risks.

The class of drugs has shown hints that it may protect against certain forms of cancer, however, and findings from these studies are still coming in.

The drugs work by blocking cyclooxygenase enzymes (COX), which are produced by the body in response to inflammation and are also produced in precancerous tissues.

The first trial, called the Adenoma Prevention with Celecoxib (APC) trial, involved about 2,000 individuals were randomly assigned to receive 200 milligrams or 400 milligrams of Celebrex twice daily, or a placebo. The individuals started the study already at high risk for this type of cancer.

Participants underwent follow-up colonoscopies after one year and after three years.

The incidence of at least one benign tumor was 45 percent lower in the groups taking Celebrex compared to those taking a placebo. The risk of developing more serious abnormalities, including invasive cancer, was 66 percent lower in the Celebrex group.

The trial was stopped early, however, when it was discovered that participants taking Celebrex had a two-to-three-times increased risk of serious adverse cardiovascular events.

The second study, called Prevention of Colorectal Sporadic Adenomatous Polyps (PreSAP) with Celecoxib Trial, looked at the effectiveness of using Celebrex to reduce the incidence of sporadic colorectal adenomas, a hereditary condition.

For this trial, 1,561 high-risk patients around the world, who had undergone removal of all colorectal polyps, received 400 milligrams of Celebrex once daily or a placebo.

The incidence of polyps was significantly lower in the Celebrex group than in the placebo group (where the rate was 49.3 percent three years out).

Participants in both trials were taking aspirin to protect their heart.

The studies still leave several questions unanswered.

"Polyps are a marker for colorectal cancer. No one ever died of polyps, but you die of cancer, and the incidence of cancer is much lower than that of polyps," Beck said. "Individual doctors are going to have to balance the risk and cost of being on those drugs."

The other question is whether the findings can be applied to all patients, because those in the study were high-risk. "That's a big question," Beck said. "Should everybody be taking them?"

More information

For more on colorectal cancer, visit the American Cancer Society.

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