Effect of treatment with 5‐α reductase inhibitors on progression in monitored men with favourable‐risk prostate cancer

Abstract

What's known on the subject? and What does the study add? Finasteride (Proscar) and dutasteride (Avodart) are 5-α reductase inhibitors (5-ARIs) used to treat LUTS in men with benign prostatic enlargement. Because these drugs suppress androgens, the theory has been put forward that 5-ARIs might prevent the development of prostate cancer. Careful analysis of two randomized controlled trials, however, showed that, in the clinical setting, this was not the case, and that these drugs can increase the occurrence of more aggressive high-grade disease. Because of this, the U.S. Food and Drug Administration did not approve 5-ARIs for the primary prevention of prostate cancer and notified healthcare professionals about a change in the 'Warnings and Precautions' for these drugs. Interest remains among some for using 5-ARIs in men diagnosed with very low-risk prostate cancer to delay the progression from clinically indolent disease to clinically significant disease requiring treatment. The present study investigated whether 5-ARI use among men with very low-risk prostate cancer in an active surveillance (AS) programme would reduce the number of cancers reclassified to clinically significant disease on surveillance biopsy. Our results do not support the use of 5-ARIs for slowing or preventing cancer progression in men with low-risk prostate cancer, but do suggest that men with very low-risk prostate cancer who take 5-ARIs for LUTS are unlikely to be at increased risk for the development of high grade disease during AS. To determine whether 5-α reductase inhibitor (5-ARI) use delays cancer reclassification in an active surveillance (AS) cohort. We performed a retrospective study of 587 men enrolled in an AS programme, who had no history of 5-ARI use. Chi-squared and t-tests were used to compare characteristics of 5-ARI users and non-users. Univariable and multivariable proportional hazards models, treating 5-ARI use as a time-dependent covariate, were used to evaluate the influence of 5-ARIs on the risk of a subsequent biopsy no longer meeting criteria for continued AS (i.e. reclassification). 5-ARI use was initiated in 47 men while on AS. Men using 5-ARIs had larger prostates and higher PSA levels at diagnosis. During 5-ARI use, PSA levels and prostate volume deceased by mean values of 47% and 11%, respectively. Men using 5-ARIs had a mean of 2.5 surveillance biopsies while on the drug. Reclassification occurred in 17% of 5-ARI users compared with 31% of non-users (P = 0.04). Multivariable models (adjusting for age, α-blocker use, PSA level, %free PSA, PSA density, prostate volume and number/percent biopsy core involvement at diagnosis) showed nonsignificant risk reductions for reclassification in 5-ARI users as determined by either tumour extent (hazard ratio [HR] = 0.37 (95% confidence interval [CI] 0.12 to 1.13), P = 0.08) or grade (HR = 0.8 (95% CI 0.25-2.59), P = 0.7). Treatment with 5-ARIs did not significantly alter the outcome of biopsy reclassification by grade in men with very low-risk prostate cancer.