Aspirin Might Cut Colon Cancer Risk : Health: Results of a study of 662,424 people are described as preliminary but intriguing. It’s too early to start prescribing the drug as a treatment, doctors say.
Aspirin, the mild-mannered pharmaceutical that has burst from the medicine cabinet in recent years as Superdrug, is now tackling cancer: Researchers reported today that people who take regular, low doses of aspirin may cut their risk of dying of colon cancer.
The finding is preliminary and already hotly debated, and researchers said it would be premature to recommend aspirin to prevent colon cancer. But they called the results intriguing, in that they suggest the disease might be controllable with a simple pill.
“It raises the possibility that we might be able to prevent one of the most important cancers in the world through a very simple treatment,” said Dr. E. Robert Greenberg, co-author of an editorial published with the study in the New England Journal of Medicine.
The findings arose from an American Cancer Society cancer-prevention study of 662,424 adults who in 1982 filled out questionnaires on issues such as diet, lifestyle, health and medication use, and then were followed for six years in order to record deaths.
The researchers found that the regular users of aspirin and other so-called non-steroidal anti-inflammatory drugs such as Bufferin or Anacin--both of which contain aspirin--were much less likely than others to die of colon cancer. For those who took at least one aspirin every other day, the fatal colon cancer risk was 40% lower.
Those who took the drugs less often appeared to have a significantly reduced chance of dying of colon cancer. Those who took acetaminophen, an alternative painkiller that does not irritate the stomach, experienced no such benefit.
But even the authors say the results are far from conclusive. The study was based on a single self-administered questionnaire. It did not address the exact dose of aspirin used, and the researchers explored only deaths, not all colon cancer cases.
Furthermore, the reasons for taking aspirin, rather than the medication itself, might explain the reduced death risk. For example, aspirin takers might see doctors more often and be more likely to have a cancer detected and treated early.
“Our finding is a very interesting research finding but it’s premature to start recommending aspirin to reduce the risk of cancer,” said Dr. Michael J. Thun of the Cancer Society, the study’s lead author. “There are too many unanswered questions.”
One skeptic is Dr. Ronald Ross, a professor at the Kenneth Norris Jr. Comprehensive Cancer Center at USC and co-author of an earlier study of 13,987 California retirees that, unlike Thun’s study, found a slightly increased risk of colon cancer among aspirin users.
“I find the magnitude of the effect alone sort of to defy credibility,” said Ross. “They find that people who use aspirin on a regular but one-day-a-month basis have a 25% reduction (in risk). That’s not credible biologically.”
Aspirin has been used for more than 80 years to treat problems such as headache, menstrual pain and muscle ache. It is also used to treat arthritis pain and is often included in cold remedies because it reduces fever.
But over the past four years, a remarkable series of findings have shown aspirin can also prevent first heart attacks, cut down the occurrence of migraine, help reduce the risk of hypertension in late pregnancy and halve the risk of stroke from an irregular heartbeat.
Aspirin is not, however, without nasty side effects. It can irritate the stomach lining, causing heartburn and nausea. Prolonged use can cause bleeding from the stomach or peptic ulcers, penetrating the wall of the stomach or small intestine.
The cancer society study is not the first to look at aspirin and colon cancer, a form of cancer that kills more than 53,000 Americans a year. The causes of the disease are unknown but risk factors include a high-fat or low-fiber diet and a history of intestinal polyps.
Two earlier studies reached conclusions similar to Thun’s. In addition, non-steroidal anti-inflammatory drugs have been found to inhibit the growth of colon tumors in animals. And one small trial in humans found that one such drug shrank large-bowel polyps, which can be precancerous.
Ross at USC, however, found no reduced risk of colon cancer from aspirin.
Researchers say a more sophisticated study is needed. They say there must be a randomized, controlled clinical trial in which two carefully matched groups are followed for years while one group is given aspirin and the other is not.
One such study is the Boston-based women’s health study, which will shortly begin tracking the effects of low-dose aspirin and several other drugs on cancer and cardiovascular disease rates. However, researchers said it could take eight to 10 years to get reliable results.
In the meantime, researchers in a separate study who followed 22,000 physicians assigned to receive either aspirin or a placebo intend to examine the data from their five years of follow-up for any light they might shed on the colon cancer issue.
“It is quite a potent drug,” said Dr. John A. Baron of Dartmouth Medical School and a co-author of the editorial. “. . . These things have to be sorted out before hundreds of thousands of people start popping aspirin.”
