Taking an aspirin a day -- or even every other day -- may prevent colon cancer from recurring, researchers report.

In a study of nearly 850 people who underwent surgery for colon cancer, those who took aspirin regularly were half as likely to die or have their cancer return than non-users, says researcher Jeffrey A. Meyerhardt, MD, MPH, of the Dana-Farber Cancer Institute in Boston.

The study was presented at the annual meeting of the American Society of Clinical Oncology (ASCO).

They study also hints that the common nonsteroidal anti-inflammatory Cox-2 inhibitor Celebrex may have a role in preventing the return of the disease.

Thirty Percent Face Colon Cancer Comeback

Though regular use of aspirin is already known to lower the risk of developing colon cancer and polyps, the current study is the largest to demonstrate that it benefits people who already have colon cancer.

Colon cancer is a highly treatable and often curable disease when localized to the bowel. Screening for the disease can include colonoscopy or sigmoidoscopy, which directly examine the colon and remove precancerous polyps. Testing stool for blood is another method used for screening adults for colorectal cancer.

Surgery is the primary form of treatment and eradicates the cancer in approximately 50 percent of patients. Recurrence of the cancer following surgery is a major problem and is often the ultimate cause of death.

Typically, surgery alone can cure about half of these colon cancers, and adding chemotherapy can prevent cancer from returning in another 20 percent or so, Meyerhardt says. But that still leaves 30 percent of people facing a potential death sentence.

Aspirin After Colon Cancer

The study included 846 people with advanced colon cancer (cancer that has spread to lymph nodes but not elsewhere in the body) who were treated with surgery followed by chemotherapy.

About halfway through their chemotherapy and again six months after it was completed, participants were asked about medications and lifestyle. They were asked how many times a week they took aspirin and other painkillers.

Nearly 9 percent said they took aspirin on a regular basis for various reasons, most frequently a 325-milligram tablet every day or every other day. And nearly 5 percent reported using the anti-inflammatory drugs Celebrex or Vioxx.

About 2.5 years later, aspirin users did better on just about every measure:

--Regular aspirin users were 55 percent less likely to have their cancer recur.
--Regular aspirin users were 51 percent less likely to die from any cause than nonusers.

There were too few people to determine whether dose mattered, but Meyerhardt says he suspects a tablet a day is best. When it comes to preventing colon cancer, it's known that a daily aspirin is better than a weekly one, he says.

Fifty-four percent of people who took Celebrex or Vioxx were still alive and cancer-free at the end of the study. Because the numbers of people in this group were small, the researchers don't know if the reduced risk associated with the Cox-2 drugs was due solely to chance. "There clearly could be benefit," he says, noting that further studies are planned.

Vioxx was pulled from the market last fall when a study testing whether it could prevent colon cancer showed a higher risk of heart disease in those taking the drug. A few months ago, manufacturer Pfizer stopped selling another Cox-2 inhibitor called Bextra for heart safety reasons, but Pfizer's Celebrex is still on the market. Pfizer is a WebMD sponsor.

Should People With Colon Cancer Start Popping Aspirin?

The jury's still out on that front.

Based on this and studies showing aspirin can prevent potentially precancerous colon polyps, Meyerhardt tells WebMD that he now recommends that his colon cancer patients take a tablet a day.

But other doctors, while optimistic, say they want to see corroboration.

"If the findings are confirmed in future studies, we may add aspirin to our armamentarium," says Sandra J. Horning, MD, the incoming president of ASCO and professor of medicine at Stanford University in California.

Stephen Shibita, MD, a cancer specialist at City of Hope in Duarte, Calif., agrees. "I personally would not make a recommendation to my patients to take aspirin at this time," he says.

Shibita says he would share the "interesting" findings but also points out that even humble aspirin carries a risk of side effects, chiefly stomach bleeding.

The American Cancer Society estimates that nearly 105,000 Americans will develop colon cancer this year; more than 56,000 will die of the disease.


By Charlene Laino, reviewed by Brunilda Nazario, MD

SOURCES: 41st Annual Meeting of the American Society of Clinical Oncology, Orlando, Fla., May 13-17, 2005. Jeffrey A. Meyerhardt, MD, MPH, associate physician, Dana-Farber Cancer Institute, Boston. Stephen Shibita, MD, department of medical oncology, City of Hope, Duarte, Calif. Sandra J. Horning, MD, incoming president, American Society of Clinical Oncology; professor of medicine, Stanford University.