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April 3, 2006 (Washington) -- The popular arthritis drug Celebrex may help to prevent colon cancer in people at high risk of the disease, but the benefits need to be weighed against the chance of developing heart problems, researchers say.
Two large studies released today show that the drug can slash the risk of developing new precancerous growths called polyps by 33% to 45% in people who already have had growths removed.
But the studies also showed that people taking Celebrex had more heart attacks, stroke, and other cardiovascular events.
Celebrex has already been shown to prevent precancerous growths in people with a rare form of inherited colon cancer, familial adenomatous polyposis.
"Now we've taken people who are not genetically predisposed to colon cancer and removed all their [precancerous growths] and followed them to see if they come back," says Monica Bertagnolli, MD, of Brigham and Women's Hospital in Boston. She is a researcher for one of the studies. .
"The study results exceeded our expectations," she tells WebMD. "Now the big challenge is to understand how these drugs affect the cardiovascular system and how to give them in an optimal way."
A member of a class of drugs known as Cox-2 inhibitors, Celebrex works by targeting the Cox-2 enzyme that plays a major role in inflammation related to arthritis and precancerous and cancerous growths.
It's the only Cox-2 inhibitor still on the market; two others, Bextra and Vioxx, were removed due to an increased risk of heart attacks and strokes.
The research was presented here at the annual meeting of the American Association for Cancer Research.
In one study, 2,035 people who had polyps removed were given either 200 milligrams or 400 milligrams of Celebrex, or placebo, twice a day. These are higher doses than are usually prescribed for arthritis treatment or other painful conditions, such as severe menstrual pain.
After one year, colonoscopy exams showed that 61% of those taking placebo had developed new polyps, compared with 34% of those on the high dose of Celebrex and 41% of those on the lower dose of the drug.
But 3.4% of people taking the drug had heart attacks, strokes, or other serious heart-related problems vs. 2.5% on placebo, a small but significant difference.
In the second study, 1,561 people who had polyps removed were given either 400 milligrams of Celebrex once a day or placebo.
By three years later, 49% of those on placebo and 34% on Celebrex had new growths, says researcher Nadir Arber, MD, of Tel Aviv Sourasky Medical Center in Israel.
Cardiovascular side effects occurred in 7.5% of those on Celebrex and 4.6% of those on placebo.
Raymond DuBois, MD, PhD, of Vanderbilt University, says one of the most exciting findings was that the drug seemed to be most effective for people who had "the biggest polyps and the most polyps removed."
The next step, he tells WebMD, is to try to tease out which people are prone to heart problems from the drug and for which people the benefits outweigh the risks.
"We can't make a generalized statement about who should and who should not get at this point," Bertagnolli agrees. "If they have questions, people need to sit down with their doctor and discuss it."
SOURCES: American Association of Cancer Research annual meeting, Washington, April 1-6, 2006. Monica Bertagnolli, MD, of Brigham and Women's Hospital in Boston. Nadir Arber, MD, of Tel Aviv Sourasky Medical Center in Israel. Raymond DuBois, MD, PhD, of Vanderbilt University.