Patients Are Reminded of Aspirin’s Risks

Cheap, ubiquitous aspirin has long been known for health benefits from basic pain relief to heart attack prevention. But after a new study this week provided tantalizing evidence suggesting that aspirin might increase survival chances for colorectal cancer patients, experts were quick to warn that the drug, a medicine cabinet staple, also had its risks.

“If I were on a desert island, one of the drugs I would choose to have with me, hands down, maybe No. 1, is aspirin,” said Dr. John A. Baron, a professor of medicine at Dartmouth Medical School. “It’s a fascinating, wonderful drug, a great drug. But it is a real drug, and it has side effects.”

Both Dr. Baron and other medical experts cautioned against starting a daily regimen of aspirin without consulting a physician, because of the risks of gastrointestinal bleeding, and the potential risk for hemorrhagic strokes, or bleeding in the brain.

“Aspirin is a drug that been with us a little over 100 years, and we continue to learn impressive and important things about its potential benefits,” said Dr. Otis Brawley, medical director of the American Cancer Society. “But it is a double-edged sword.”

The study found that patients with colorectal cancer who were regular aspirin users had a much better chance of surviving than non-users, and were almost one-third less likely to die of the disease, while those who began using aspirin for the first time after the diagnosis cut their risk of dying by almost half.

Earlier studies had shown that people who took aspirin regularly were less likely to develop tumors of the colon, but the new study, published in The Journal of the American Medical Association, is the first to have found that patients who had colorectal cancer and took aspirin survived longer.

One colon cancer expert who commented on the recent study called it “remarkable” and “revolutionary.” But then his patients started seeking advice, and he was more circumspect.

“It’s one thing to talk philosophically,” said the expert, Dr. Alfred I. Neugut, an oncologist from the College of Physicians and Surgeons at Columbia University who wrote an enthusiastic editorial on the study in this week’s Journal of the American Medical Association. “But this is only one study. To know that it’s true, it needs to be repeated. Every experiment needs to be repeated once.”

The new study was not a controlled clinical trial, where patients are randomly assigned to receive either a particular treatment or a placebo. That kind of study is considered the gold standard for determining clinical recommendations in medicine, but it is also far more expensive and cumbersome. Observational studies, like this new one, can be weaker or misleading.

One clinical trial is under way in Asia, where the National Cancer Center of Singapore is enrolling 2,660 patients with nonmetastatic disease in Hong Kong, India, Indonesia and Singapore, who will continue their treatment and be randomly assigned to either get aspirin or a placebo daily for up to three years, according to the National Cancer Institute Web site.

Most colorectal cancer tumors are positive for cyclooxygenase-2, or COX-2, an enzyme that is not expressed in a healthy colon but flares up under certain circumstances. The enzyme appears to be involved in fueling abnormal cell growth and contributing both to the development and spread of the cancer, said Dr. Andrew T. Chan, the author of the new study.

Aspirin’s anti-cancer property is believed to be linked to its action as a COX-2 inhibitor.

A clinical trial of another COX-2 inhibitor, celecoxib, which has the brand name Celebrex, is in the planning stages and will be enrolling patients early next year, Dr. Chan said. Although more is known about aspirin’s effects on preventing colorectal polyps and tumors than other cancers, some studies have also hinted that aspirin could reduce the risk of developing breast, lung and prostate cancers, which are also associated with inflammation, Dr. Brawley said.

“It seems like — and we’re still talking in theory in some instances here — there is a relationship between inflammation and cancer in certain tumors,” Dr. Brawley said. “And these drugs appear to be beneficial because they are anti-inflammatory, and they inhibit inflammation by inhibiting COX-1 and COX-2.”

The new colorectal cancer study found not only that patients who took aspirin regularly after a diagnosis of colorectal cancer had a better chance of survival than those who did not, but also that those who had tumors that overexpressed the COX-2 enzyme were particularly responsive to the aspirin.

Dr. JoAnn E. Manson, chief of preventive medicine at Brigham and Women’s Hospital, which is affiliated with Harvard Medical School, warned about the risks of using even small doses of aspirin on a daily basis, saying that in a large women’s health study, half doses of baby aspirin were associated with a 40 percent increase in serious gastrointestinal bleeds that required transfusions.

But, she acknowledged, patients who already have colorectal cancer may feel they do not have the luxury of waiting for additional results.

“I don’t think everyone should be running out and taking aspirin,” she said, “But there may be some patients who would benefit from it at this point; and if they talk with their doctors they may learn they’re reasonable candidates, and some of them may not be in a position to wait.”

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