The Prostate Cancer Prevention Trial was a study that enrolled more than 18,000 men to determine whether finasteride reduced the risk of developing prostate cancer. Each man in the study was randomly assigned to take a pill each day for 7 years. The pill consisted either of finasteride or a placebo, but the men didn ™t know which pill they were taking.

At the end of the study, the men taking finasteride were about 25% less likely to have developed prostate cancer than those getting the placebo. But the men taking finasteride who did develop prostate cancer were more likely to have cancers that appeared to be of a higher grade when viewed under a microscope. These cancers may be more likely to grow and spread. The reason for the higher grade cancers is not known. The study researchers are continuing to watch these men to see if these cancers truly are more aggressive.

The men taking finasteride were more likely to experience sexual side effects, such as decreased sexual desire and episodes of impotence, than those taking placebo. But they were less likely to have urinary problems, such as difficulty urinating and inability to hold urine in (incontinence).

Each man considering taking finasteride to reduce his risk of developing prostate cancer should consider the results of this study carefully, and should discuss the possible pros and cons with his doctor when deciding on an appropriate course of action.