Women who take aspirin on a regular basis reduce their risk of developing malignant melanoma, the deadliest form of skin cancer, medical researchers have discovered.
An analysis of more than 60,000 women, participants in the Women's Health Initiative, a vast ongoing health research project that is the largest cancer prevention investigation of its kind, also demonstrated that the longer women took aspirin, the lower their risk.
The initiative is sponsored by the National Institutes of Health and includes a broad cross-section of women nationwide. The focus, however, in this project was on older white women because of an elevated melanoma risk. Their ages ranged from 50 to 79.
"Aspirin has already been shown to have protective effects on cardiovascular disease and colorectal cancer in women," said Dr. Jean Tang of Stanford University in California, a senior author of the research. The new findings, she said, suggest a potentially new mechanism of action for the over-the-counter drug.
Reporting in today's online edition of the journal Cancer, Tang and her colleagues found an average melanoma risk reduction of 21 percent. But the protective effect, according to data, increased with time. At the one-year mark there was an 11 percent risk reduction and a 22 percent lowering of melanoma's risk by the fourth year.
At the fifth year the risk reduction rose to 30 percent.
Melanomas can develop anywhere but usually are found on areas of the body receiving prolonged sun exposure. An estimated 76,250 new cases are expected in the United States this year, according to the American Cancer Society. Despite the positive findings, the California researchers are not endorsing widespread use of aspirin as a melanoma preventive.
Foremost, they couldn't say how much aspirin should be taken because the study involved women who consumed a wide range of doses, none of them the low-dose version of the medication. Also, some, not all, of the participants took aspirin daily.
People of color were excluded but research shows that darker complexions do not provide immunity to melanoma.
Yet, the study shows the potential new aspirin role, experts say.
"Nothing surprises me about aspirin. We really don't quite appreciate it as much as we should but it's time we started doing so," said Dr. Basil Rigas, an expert in nonsteroidal anti-inflammatory drugs -- the class to which aspirin belongs.
Rigas, dean of clinical affairs at Stony Brook University School of Medicine, was not involved in the new analysis, but he said the drug's mechanism in melanoma prevention is likely the same as it is in other vexing medical conditions.
"Aspirin is the prototypical anti-inflammatory drug," Rigas said. "What links cancer, heart disease and Alzheimer's is inflammation. So all diseases that have their roots in inflammation may be amenable to the preventive effects of aspirin."
He said further studies are needed to better understand how the pennies-per-dose medication acts as a melanoma preventive. It already has a long list of beneficial roles, Rigas said. Aspirin cuts heart attack risk by thinning the blood and inhibiting the aggregation of sticky disc-shaped cells called platelets involved in clotting.
As an analgesic, it knocks out pain by blocking the activity of the so-called COX enzymes. It reduces fever by acting directly in the brain.
Still, aspirin has side effects, Rigas said, such as stomach bleeding and ulcers. But Rigas calls aspirin "a very talented" compound. If it were a new medication going before the U.S. Food and Drug Administration for approval, Rigas said, aspirin would probably be deemed for prescription-use only because of its powerful preventive capacities.