Finasteride, a 5-alpha reductase inhibitor, has long been linked to high-grade prostate cancer, hindering its use as a chemoprevention agent. According to a long-term analysis of the Prostate Cancer Prevention Trial (PCPT), however, no such increased risk exists, potentially clearing finasteride as a safe and effective chemoprevention agent for prostate cancer.1 The data were published in the New England Journal of Medicine.

“Since the PCPT trial was published years ago, there’s been this concern about finasteride increasing the rate of a high-grade prostate cancers,” Guilherme Godoy, MD, Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, told Cancer Therapy Advisor. In 2003, the Prostate Cancer Prevention Trial (PCPT), which included nearly 19,000 men, showed that finasteride decreased the risk of developing prostate cancer by approximately 25%, yet paradoxically, seemed to increase their risk for high-grade prostate cancer.

“That concern has put this drug behind in terms of it being widely adopted as a preventive medication in this disease,” Dr Godoy said. The drug label for finasteride currently has a black box warning about the increased risk of high-grade prostate cancer.

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During an interview with Cancer Therapy Advisor, Bobby Liaw, MD, assistant professor of medicine, hematology, and medical oncology at Mount Sinai in New York, New York, expressed a similar sentiment, describing the use of finasteride as a chemoprevention agent as a “long-standing controversy.” He said, “The struggle has always been whether or not it actually increased risk of the [high-grade prostate cancer].”

To determine whether a greater number of high-grade prostate cancers could have indeed led to an increase in prostate cancer mortality — and put this concern to rest — study researchers calculated the cumulative incidence of death from prostate cancer for PCPT participants.

They found that at a median follow-up of 18.4 years, 42 deaths due to prostate cancer occurred in the finasteride arm (9423 individuals) and 56 deaths due to prostate cancer occurred in the placebo arm (9457 individuals). Men on the finasteride arm ultimately had a 25% lower risk of death from prostate cancer than those on the placebo arm (hazard ratio [HR], 0.75; 95% CI, 0.50–1.12), a difference that was not statistically significant.

“The fact that there was no difference in survival can be an interpreted in the sense that, if finasteride was indeed causing high-risk cancers, that would definitely impact survival and cancer-specific survival negatively,” said Dr Godoy. “We have waited long enough, and now with this last piece of data, we have enough research … to confirm that those concerns are not validated.”

Dr Liaw shared a similar view: “When I review a lot of the literature myself, I find that that risk of developing a high-risk prostate cancer is definitely not as big of a risk as we had initially thought that it would have been if we based everything on that original finding about finasteride.”

However, Dr Liaw cautioned, if finasteride is to be recommended to patients, they will need to have regular prostate cancer screenings and be monitored. “[Use of finasteride in prostate cancer] is not a common practice right now, and so there has to be a little bit of learning as to what’s the right way for us to monitor these patients,” he said. “These are things that probably should be considered before people make big blanket statements that everyone should potentially be on finasteride to help with reducing prostate cancer risk.”

Reference

  1. Goodman PJ, Tangen CM, Darke AK, et al. Long-term effects of finasteride on prostate cancer mortality. N Engl J Med. 2019;380(4):393–394.