Daily use of aspirin, ibuprofen, and other non-steroidal anti-inflammatory drugs (NSAIDs) may lower men's chances of getting prostate cancer, said researchers in the Mayo Clinic Proceedings (Vol. 77: 219-225).

"Over a period of about five and a half years of follow-up, the risk of prostate cancer was lower in men who reported taking NSAIDs daily, compared to men who did not report doing so," said the study's lead author, Rosebud O. Roberts, MD, assistant professor of epidemiology at the Mayo Clinic in Rochester, Minn.

Roberts and colleagues studied 1,362 men aged 50 to 79 in Olmstead County, Minn., for six years, tracking how many were diagnosed with prostate cancer and whether the men were taking NSAIDs daily or not.

Considering all age groups together, those using NSAIDs daily were about half as likely to develop prostate cancer as those not using them.

But the protective effect of NSAIDs increased markedly as age went up.

Among daily NSAID users, there was a 12% reduced risk of prostate cancer in those aged 50 to 59, a 60% lower risk in those 60 to 69, and an 83% drop in risk for those 70 and over.

The chances of getting prostate cancer go up with age.

The researchers say that rather than preventing the disease entirely, NSAIDs might just slow it down so it becomes less likely to grow enough to produce any symptoms.

Roberts said the study did not determine the best dose to use, or how long it's necessary to use NSAIDs to get the protective benefit.

And she cautioned that regular use of NSAIDs can raise the risk of ulcers and strokes.

"Men should not begin taking these drugs just on the basis of this study; they should discuss it with their doctors and follow their doctors' recommendations," she said.

Roberts said NSAID use may lower prostate cancer risk by interfering with an enzyme called cyclooxygenase (COX).

The COX enzyme promotes cancer by stimulating cell division, and interfering with the body's attempts to destroy cells that may be in the process of turning cancerous, she noted. It's been linked to cancers of the breast, colon, and others as well, she noted.

It's possible that the lower rates among NSAID users were due to other things the men were doing, such as eating less red meat and animal fat, or taking vitamin E or selenium, all known or believed to lower risk, said Michael J. Barry, MD, of Massachusetts General Hospital in Boston, in an editorial published along with the study.

But NSAIDs are also known to offer some protection against heart disease, and now men who earlier were thinking about using the drugs regularly for that reason may have another reason to do so – lowered chances of prostate cancer, he added.

A prostate cancer expert with the American Cancer Society (ACS) praised the study.

"This well designed, well-executed study provides some very exciting information," said Durado Brooks, MD, director of prostate and colorectal cancer control for the ACS.

Like all research producing relatively new findings, it will need to be confirmed by additional studies before scientists can be sure its conclusions are accurate, he added.

Future studies should include adequate numbers of African-American men, said Brooks, noting that the Mayo group looked only at whites.

The potential payoff of additional research – including looking for similar patterns in earlier-collected data – could be very large, he said.

"If these effects are confirmed in additional studies, it could give us a useful new tool for prostate cancer prevention, at least in some men, and that would be a very welcome advance indeed," Brooks said.