The influence of unscheduled biopsies on prostate cancer detection in the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial

Abstract

1504^ Background: REDUCE is an ongoing 4-year, international, randomized, placebo-controlled study investigating the effect of dutasteride on the incidence of biopsy-detectable prostate cancer (PCa). We assessed the influence of prostate specific antigen (PSA)-driven, unscheduled biopsies on PCa detection. Methods: Eligible subjects were aged 50–75 years with serum PSA 2.5–10 ng/mL (50–60 years) or 3–10 ng/mL (>60 years) and a negative 6–12-core biopsy ≤6 months before enrollment. Protocol-mandated transrectal ultrasound directed biopsies (10 cores) were taken at 2 and 4 years; we report unblinded 2-year data. Results: Of the 8108 subjects in the efficacy population (subjects with no PCa in baseline biopsy as assessed by Central lab and who took at least one dose of study medication), 356 subjects (4.4%) underwent an unscheduled biopsy (0–18 months), and 6460 subjects (79.7%) underwent a protocol-mandated (scheduled) biopsy (19–24 months). Rising PSA was the primary reason for an unscheduled biopsy. PCa was diagnosed in 60 subjects (16.9%) at an unscheduled biopsy compared with 950 subjects (14.7%) at scheduled biopsy. Subjects with PCa on unscheduled, compared with scheduled, biopsy had higher baseline PSA (6.63 vs. 6.06 ng/mL), lower % free PSA (13.2% vs. 15.5%); there was no difference in the mean number of baseline biopsy cores (8.6 vs. 8.4). Conclusions: Although unscheduled biopsies in REDUCE were slightly more likely to result in a cancer diagnosis and have a higher Gleason score, the small number of such biopsies (356/6591, 5.4% of subjects biopsied) would not cause a significant ascertainment bias. This contrasts the prostate cancer prevention trial (PCPT), where close to 40% of subjects had for-cause biopsies (most often PSA-driven), creating a substantial detection bias for high-grade cancers. [Table: see text] [Table: see text] ASCO Conflict of Interest Policy and Exceptions In compliance with the guidelines established by the ASCO Conflict of Interest Policy (J Clin Oncol. 2006 Jan 20;24[3]:519–521) and the Accreditation Council for Continuing Medical Education (ACCME), ASCO strives to promote balance, independence, objectivity, and scientific rigor through disclosure of financial and other interests, and identification and management of potential conflicts. According to the ASCO Conflict of Interest Policy, the following financial and other relationships must be disclosed: employment or leadership position, consultant or advisory role, stock ownership, honoraria, research funding, expert testimony, and other remuneration (J Clin Oncol. 2006 Jan 20;24[3]:520). The ASCO Conflict of Interest Policy disclosure requirements apply to all authors who submit abstracts to the Annual Meeting. For clinical trials that began accrual on or after April 29, 2004, ASCO's Policy places some restrictions on the financial relationships of principal investigators (J Clin Oncol. 2006 Jan 20;24[3]:521). If a principal investigator holds any restricted relationships, his or her abstract will be ineligible for placement in the 2009 Annual Meeting unless the ASCO Ethics Committee grants an exception. Among the circumstances that might justify an exception are that the principal investigator (1) is a widely acknowledged expert in a particular therapeutic area; (2) is the inventor of a unique technology or treatment being evaluated in the clinical trial; or (3) is involved in international clinical oncology research and has acted consistently with recognized international standards of ethics in the conduct of clinical research. NIH-sponsored trials are exempt from the Policy restrictions. Abstracts for which authors requested and have been granted an exception in accordance with ASCO's Policy are designated with a caret symbol (^) in the Annual Meeting Proceedings. For more information about the ASCO Conflict of Interest Policy and the exceptions process, please visit www.asco.org/conflictofinterest .