Few doctors prescribe finasteride to prevent prostate cancer, despite effectiveness

Most physicians are reluctant to prescribe the drug finasteride to prevent prostate cancer in older men with elevated risk of the disease, despite evidence that the drug can reduce risk by about a quarter, researchers said Tuesday.

“There are no other proven ways of reducing yours risk of prostate cancer -- this is the only one,” Dr. Ian M. Thompson of the University of Texas Health Science Center in San Antonio, told Bloomberg. Its use could reduce new diagnoses by “tens of thousands,” he said. Thompson was the lead author of a 2003 report that showed that the drug, sold by Merck under the brand name Proscar, could reduce the risk of prostate cancer among such men from 24% to 18%. Another study earlier this year showed that a second drug, dutasteride, might be even slightly more effective.

About 217,730 men will be diagnosed with prostate cancer this year, according to the National Cancer Institute, and about 32,000 will die from it. That makes it the second-leading cause of cancer death among men, following only lung cancer.

Risk factors for prostate cancer include being over the age of 65, having elevated levels of prostate-specific antigen (PSA), a family history of the disease and being African American.

In the new study, Dr. Linda S. Kinsinger of the Veterans Health Administration National Center for Health Promotion and Disease Prevention and her colleagues surveyed a random sample of 325 VHA urologists and 1,200 VHA primary care physicians to determine how their prescribing practices changed from 2000 through 2005, a period that included the widely heralded finasteride trial. The researchers reported in the September issue of the journal Cancer Epidemiology, Biomarkers & Prevention that the use of finasteride did increase somewhat during the period, but to treat benign prostatic hyperplasia, not to prevent prostate cancer. Fully 64% of urologists and 80% of primary-care physicians said they never prescribed the drug for prevention, and 52% of the latter group said they did not even know that the drug could be used for that purpose.

One concern among urologists was that the 2003 study suggested that, even though finasteride reduced the risk of prostate cancers, those who did develop the disease might be more likely to develop a highly aggressive form of the disease. Researchers have subsequently shown, however, that that was an artifact of the study and that the drug doesn’t increase the risk of such tumors.

“The prospect of chemoprevention is a difficult one for patients and physicians,” Kinsinger said in a statement. She compared using finasteride to ward off prostate cancer to using statins to ward off heart disease. The primary difference between the two, she added, is that the effects of statins can be monitored by measuring cholesterol levels, but there is no analogous marker to show that finasteride is working. The only marker is not developing cancer.

The primary side effect of finasteride is that it increases hair growth. In fact, the drug is also sold under the brand name Propecia to promote new hair growth in the balding. The amount of drug in Propecia is about 20% of that in Proscar.

Thomas H. Maugh II/Los Angeles Times