New analysis: Finasteride does not appear to increase high-grade PCa risk

An extensive re-analysis of the drug finasteride (Proscar) shows that it reduced the risk of developing prostate cancer by about 30% compared with the initial finding of a 25% reduction in risk.

When the initial results of the Prostate Cancer Prevention Trial were announced in 2003, researchers cautioned that men in the study who developed prostate cancer while taking finasteride were more likely to have high-grade cancers. But the new analysis, which used data that included endpoints 3 months longer than in the original report, showed finasteride did not induce aggressive cancers, said Ian Thompson, MD, of the University of Texas Health Sciences Center at San Antonio, who led the original PCPT and the recent re-analysis.

He and colleagues estimated rates of high-grade prostate cancer based on an analysis that incorporated grading information from radical prostatectomies in 500 subjects diagnosed with cancer. The resulting estimates were high-grade cancer rates of 8.2% (placebo) versus 6% (finasteride), a 27% risk reduction (p=.02) with finasteride. They also examined the impact of biopsy sensitivity on the risk relative of high-grade prostate cancer and found that differential sensitivity of biopsy between the treatment arms can have a significant impact on risk ratio estimates.

These collective results, published in the May 18 online edition of Cancer Prevention Research and presented at the recent AUA annual meeting in Orlando, FL, suggest that the observed unadjusted higher risk of high-grade disease with finasteride seems to have been due to facilitated diagnosis resulting primarily from increased biopsy sensitivity with finasteride. Therefore, men undergoing regular prostate cancer screening or who express an interest in cancer prevention should be informed of the opportunity to take finasteride for preventing prostate cancer, Dr. Thompson said.