"We showed that men who regularly took certain medications like Aspirin and other non-steroidal anti-inflammatory drugs, or NSAIDS, had a lower serum PSA level," said the study's first author, Dr. Eric Singer, a urology resident at the University of Rochester Medical Center in New York.
"But there's not enough data to say that men who took the medications were less likely to get prostate cancer."
Doctors watch prostate-specific antigen (PSA) levels because high levels in the bloodstream may point to early stages of prostate cancer or other prostate conditions.
When Singer and his colleagues analyzed data from 1,319 U.S. men over the age of 40, they found those who took non-steroidal anti-inflammatory drugs like Advil nearly every day had PSA levels that were about 10 per cent lower compared with men who did not take the drugs.
The results "are consistent with previous reports that NSAID use is a protective factor for the development of prostate cancer," the team wrote in the Oct. 15 issue of the journal Cancer.
A similar link was found for acetaminophen or Tylenol, but it was not statistically significant since so few men in the cross-sectional study were taking it, the researchers said.
It's too soon to conclude that a lower PSA level translates to a lower risk of prostate cancer, since the marker could be elevated by inflammation that isn't related to cancer, Singer said.
It's also possible PSA levels may appear to lower after taking NSAIDS if the medications artificially mask a man's risk, he added.
If the findings hold true, it could change when doctors decide whether to order biopsies to check for a tumour, but a clinical trial that follows men who regularly take NSAIDS is needed to see how it affects the risk of prostate cancer before researchers can answer the question.
In the meantime, the results show why it's so important for patients to tell their doctors about all medications, prescription and over-the-counter, that they are taking, said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society, which published the study.
Clinical trials are underway to help clarify whether PSA tests help save lives. The test has a high rate of false-positive results that suggest cancer when none is present, which can lead to invasive follow-up tests in healthy men.