Assessing benefit and risk in the prevention of prostate cancer: the prostate cancer prevention trial revisited.

Author(s): Klein EA,  Tangen CM,  Goodman PJ,  Lippman SM,  Thompson IM

Journal: J Clin Oncol

Date: 2005 Oct 20

Major Program(s) or Research Group(s): CCOP, COPTRG, PUCRG

PubMed ID: 16157937

PMC ID: not available

Abstract: PURPOSE: The Prostate Cancer Prevention Trial demonstrated a 25% reduction in period prevalence of prostate cancer in men randomly assigned to 5 mg/d of finasteride. However, widespread use of finasteride for prevention is inhibited by the observed increased risk of high-grade disease. We present a model of risk and benefit that estimates the potential effects of histologic artifact in the assignment of excess risk for high-grade disease and the possible effect of overdetection bias introduced by finasteride-induced volume reduction. METHODS: The absolute benefit/absolute risk ratio of finasteride use was estimated by calculating the ratio of absolute risk reduction in the finasteride arm to the absolute risk of excess high-grade cancers. This ratio was recalculated for assumptions that 10%, 25%, or 50% of the excess high-grade cancers were due to histologic artifact, and that there was a 25% overdetection bias in the finasteride arm. RESULTS: For all cancers the absolute benefit/absolute risk ratio increased from 4.6:1 to 5.1:1, 6.2:1, and 9.2:1 for assumptions of 10%, 25%, or 50% histologic artifact, respectively. The ratio increased from 4.6:1 to 8.2:1 for the assumption of 25% overdetection bias, and to 9.1:1, 10.9:1, and 16.3:1 for combined assumptions of 25% overdetection bias and 10%, 25%, or 50% histologic artifact, respectively. CONCLUSION: The adoption of a prevention strategy hinges on potential benefits weighed against potential risks. This model demonstrates the magnitude of effect for a hypothesized range of histologic artifact and overdetection bias on the assessment of risk versus benefit for finasteride.