The Food and Drug Administration expanded the warning label on certain prostate drugs, warning they may increase the risk of being diagnosed with a more severe form of prostate cancer.
The drugs included in the warning change are of the 5-alpha reductase inhibitor class, which includes GlaxoSmithKlines (NYSE:GSK) Avodart and Mercks (NYSE:MRK) Proscar, which are both used to shrink the prostate.
The drugs are also known as dutasteride and finasteride, respectively, and are additionally marketed under the names Propecia and Jalyn.
While the drugs have been shown to reduce the risk of prostate cancer overall, and the FDA said the risk of it turning into a more serious form of cancer appears to be low, it recommended healthcare professionals be aware of it.
The agency is basing its conclusions on a review of two studies of some 18,800 men over the age of 50 that used the drugs for several years. While both trials showed an overall reduction in prostate cancer diagnoses, they also showed an increased incidence of high-grade prostate cancer.
The FDA said roughly 5 million male patients received a prescription in this class of drugs from 2002 to 2009.