THURSDAY, Oct. 30, 2008 (HealthDay News) -- A new study shows that men who take cholesterol-lowering drugs called statins have lower blood levels of prostate-specific antigen (PSA), a biomarker for prostate cancer risk.
That drop in PSA levels doesn't necessarily mean the drugs protect against disease however, researchers say.
But it's possible that statins may offer some protection against the disease, said Dr. Robert Hamilton, one author of the report in the Oct. 28 issue of the Journal of the National Cancer Institute. He worked on the study while a research fellow at Duke University; he is now a urology resident at the University of Toronto.
"The reduction in PSA was in proportion to the dose of statins that were taken and to the reduction of cholesterol levels," Hamilton said, indicators of a possible protective effect.
The study was done because of "encouraging recent data" from four previous studies showing an association between statin therapy and reduced PSA levels, and a reduced risk of advanced prostate cancer, he said.
The study followed 1,214 men who were prescribed statins between 1990 and 2006 at the Durham Veterans Affairs Medical Center in North Carolina. PSA levels declined by about 4 percent after statin therapy was started, with the greatest reductions seen in men who took the largest doses of statins and had the largest drops in blood cholesterol levels.
The results parallel those of a study reported in 2005 by a group led by Dr. Dov Kadmon, a professor of urology at the Baylor College of Medicine.
"Our study was the first to show a relationship between PSA levels and either lowering of cholesterol or treatment with statins," Kadmon said. "We could not distinguish whether lowering cholesterol or statin treatment was responsible, because our study was not designed to show that."
Kadmon and his colleagues followed 100 commercial airline pilots, a group chosen because federal regulations require them to have regular medical exams. The five-year study showed that "pilots on statins had a 46 percent decrease in PSA levels, while the control group had a slow increase in PSA levels, which are known to go up with age," Kadmon said.
The study was too small and too short to tell whether statins might protect against prostate cancer, Kadmon said. "But we know that when men have higher PSA levels, there is a higher chance that they will be diagnosed with prostate cancer," he said. "It is worth looking into by conducting a larger study."
"There is no question that a large, randomized, controlled trial with a long follow-up would most likely answer the question," Hamilton said. "It would be an expensive, huge undertaking."
Why statins affect PSA levels is unclear, Hamilton said. "We have some idea of how statins interact with prostate biology," he said. "But we don't know the exact mechanism by which statins influence PSA."
The anti-inflammatory action of statins is one of the possible mechanisms, Hamilton said. "We need to learn more about prostate cancer and statins before we launch a huge study," he added.
Statins and other drugs that lower cholesterol are described by the American Heart Association.