Just as it's harmful for women who take a selective serotonin reuptake inhibitor (SSRIs) like fluouxetene (Prozac) and paroxetine (Paxil) or a cardiac or antipsychotic drug along with the breast cancer drug tamoxifen, the results of a prostate-specific antigen (PSA) test may be altered by the use of common drugs, like statins, thiazide diuretics and non-steroidal, anti-inflammatory drugs (NSAIDs).

The effect of 10 drugs in these three categories had on lowering serum PSA levels among more than 1,850 men (age 40 and older) with no history of prostate cancer was slight but noticeable after one year, with a high of 6 percent for thaizide diuretics (drugs used to treat edema and hypertension). Real change came at the five-year mark, however, when the use of any one kind of drug artificially and exponentially lowered PSA levels anywhere from four to six times below normal. For example, the use of thaizide diuretics reduced PSA levels by a surprising 26 percent.

The drop in PSA levels was even more pronounced after five years among men who took a diuretic along with a statin drug by 36 percent, although using a calcium channel blocker to treat high blood pressure inhibited that effect. And, because many older patients use at least one, if not more, of these medications at the same time, researchers estimate their effect on artificially lowering PSA levels among far greater numbers of men could be huge.

But there's one more tantalizing possibility scientists are considering: This trio of drug classes may create a protective effect against cancer, not at all a pipe dream, considering statin drugs and NSAIDs are already being studied for that reason.

Journal of Clinical Oncology August 2, 2010

Drugwatch.com August 9, 2010

healthfinder.gov August 6, 2010