Painkillers, prostate cancer and the PSA test

Many men remain undecided about whether to have the prostate-specific antigen (PSA) test for prostate cancer, as part of a routine health check. On the one hand, screening can detect cancers at an early stage; on the other, it may lead to needless investigations, and treatments that have risks of serious side effects. That's because many prostate cancers are very slow-growing and could safely be left undiagnosed and untreated.

Now a new study threatens to muddy the waters further. It suggests that men who regularly take aspirin, ibuprofen and other nonsteroidal anti-inflammatory drugs (NSAIDs) could have lower blood levels of PSA, the protein that is a marker for prostate cancer.

In the study, researchers looked at the PSA levels of more than 1,300 men over age 40. They found that men who used NSAIDs regularly had PSA levels that were around 10 percent lower than those of men who did not take these drugs.

The problem is, researchers don't know what this signifies. Do men who take these drugs run the risk of cancer not being detected because NSAIDs affect levels of PSA in their blood? Or do men who take NSAIDs have less of this protein because they are less likely to have prostate cancer?

The prostate makes PSA to keep semen in a liquid, fluid state. When cancer is present, more PSA seeps from the prostate into the blood. That's why the test is useful in helping to detect cases of suspected prostate cancer, although its inclusion in routine health checks is controversial.

This isn't the first study to look into a relationship between NSAID use and prostate cancer, but it is among the first to focus on how these drugs affect PSA levels. Previous studies have suggested that regular use of NSAIDs may help prevent several types of cancer, including prostate cancer. The current study doesn't contradict these findings (in fact, it may support them), but it raises the possibility that NSAIDs could lower PSA levels without having an effect on cancer development. This means some prostate cancers could go undiagnosed for longer.

What you need to know. It's possible that aspirin and NSAIDs could confuse the results of the PSA test, but it's equally possible that they may reduce the risk of cancer. We won't know until further studies have been done. In the meantime, it's always a good idea to tell your doctor about any medications you are taking, whether prescription or over-the-counter. Medicines for an enlarged prostate, for example, are known to affect the results of the PSA test. And if you're unsure about whether to have the PSA test at all, be sure to discuss the pros and cons with your doctor.

—Sophie Ramsey, Patient editor, BMJ Group

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Read more on the risk factors and tests for prostate cancer (free), and find out what treatments work for an enlarged prostate (subscribers only).