Pros, cons of finasteride to prevent prostate cancer should be considered

Findings by UT Southwestern Medical Center researchers encourage men to weigh both the potential benefits and side effects of the drug finasteride before taking it to prevent prostate cancer.

In today's online issue of Cancer, UT Southwestern doctors analyzed data gathered by the National Cancer Institute's Prostate Cancer Prevention Trial, or PCPT. The trial, which began in October 1993, was designed to test whether finasteride could prevent prostate cancer in men 55 years of age and older. It was stopped early in June 2003 when an analysis showed that finasteride reduced the risk of developing prostate cancer by 25 percent.

UT Southwestern's analysis of the PCPT data indicates that cost effectiveness and quality of life issues associated with taking the drug are not clear cut, said Dr. Yair Lotan, assistant professor of urology and the Cancer study's senior author. The PCPT data show that in addition to preventing prostate cancer, finasteride also reduces urinary-tract symptoms associated with benign prostatic hyperplasia. It also decreased sexual desire and caused impotence in 5 percent of the trial participants. Some PCPT participants who did develop prostate cancer also had high-grade tumors, although there is ongoing debate whether this result might have been due to sampling bias.

“Finasteride is currently the only drug that has been shown to prevent prostate cancer in a large randomized trial but is used for this purpose in very few men,” Dr. Lotan said. “A large number of patients are currently taking over-the-counter supplements to prevent prostate cancer, even though there is no scientific evidence to support these products' claims. It's important for patients to be aware of this scientific trial and to ask their doctors if finasteride could benefit them.”

In light of all these pros and cons, Dr. Lotan said physicians and patients need to work together closely to weigh how finasteride could affect quality of life on a case-by-case basis.

“With the exception of skin cancer, prostate cancer is the most common cancer in American men,” Dr. Lotan said. “Men who are at low risk for prostate cancer might view taking finasteride as not very cost effective when considering its impact on their quality of life. On the other hand, patients at high risk might see it as cost effective because it lessens their chances of developing prostate cancer.

“Because there is some complexity to the PCPT I think doctors hesitate to discuss its results. While I'm not advocating for the drug, I think physicians should mention finasteride, especially when their patients are asking questions about ways to prevent prostate cancer. Patients should understand and be aware of the proven science that's out there.”