The drug finasteride plays a curious dual role: It can help a man grow back thinning hair and also alleviate urinary problems. The drug achieves both effects by ratcheting down production of dihydrotestosterone, a hormone linked to male pattern baldness and enlargement of the prostate.
Researchers funded by the National Cancer Institute now report that finasteride also prevents some cases of prostate cancer. Merck and Company of Whitehouse Station, N.J., markets finasteride as Proscar for prostate problems and, in a lower dose, as Propecia for baldness. The company has not announced whether it will ask the Food and Drug Administration to approve finasteride for prevention of prostate cancer. Some cancer specialists, however, doubt that the drug will have widespread value in protecting men against the disease.