COMMENTARY

18-Year Follow-up Data Vindicate Finasteride as a Prostate Cancer Preventive

Gerald Chodak, MD

Disclosures

August 14, 2018

Hello. I am Dr Gerald Chodak, for Medscape. Today's topic is the prevention of prostate cancer.

About 25 years ago, a prospective, randomized trial was initiated to determine whether the drug finasteride could reduce the incidence of prostate cancer. The initial findings[1] showed that the drug prevented prostate cancer in a significant percentage of participants. However, there was a small but statistically significant increase in diagnosing more aggressive prostate cancers [in those who received finasteride]. On the basis of that finding, the US Food and Drug Administration (FDA) did not grant finasteride an approval for prevention but instead issued a warning about taking the drug, even for men with benign prostatic hypertension.

Fast-forward and we find a presentation by Thompson and colleagues,[2,3] delivered at the American Urological Association (AUA) 2018 Annual Meeting, [and reporting on that trial] with about 18 years of median follow-up. The study, which initially enrolled almost 19,000 men, has now been found to show a significant (roughly 25%) reduction in the death rate from prostate cancer [in participants who received finasteride]. The initial concerns about causing or finding more high-grade cancers were not borne out by an increase in the death rate related to prostate cancer.

Despite this rather positive finding, many men still may not opt to take the drug, as there were significant side effects. The study reported a 6% higher incidence of impotence in the finasteride group and a 5% higher incidence of reduced volume of the ejaculate. About 1.5% more men complained of breast tenderness and breast enlargement, and 1.5% more men had decreased libido. Going forward, many men may [decide] that the benefit may not be worth the risk.

Several questions need to be addressed. Will Merck or anyone else resubmit the data and reapply for US Food and Drug Administration (FDA) approval [for this indication]? Whether they would receive that is, of course, unknown. If they choose not to make a submission, the question is whether there could be any medical liability for physicians who either don't talk about this study or present it in a way that negates the positive findings. If a man is diagnosed [with prostate cancer] later on, after he could have been offered a drug [that may have prevented the development of prostate cancer], will the doctor be at risk?

If Merck decides to resubmit finasteride for FDA application and approval [for this indication], what would that mean since it is now a generic drug? Would generic makers of finasteride also have an ability to promote their drug as a chemopreventive?

For now, this is an important finding. It offers an opportunity to save lives from prostate cancer. The question is what will be done going forward. I look forward to your comments. Thank you.

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