Transition of a clinical trial into translational research: the prostate cancer prevention trial experience.

Large clinical trials provide a tremendous opportunity to integrate correlative, comprehensive biological studies with invaluable repositories of biospecimens and clinical and other data from the trial. The Prostate Cancer Prevention Trial (PCPT) was a phase III randomized, double-blind, placebo-controlled clinical trial of finasteride in 18,882 men. Clinical data and blood and tissue specimens were collected at baseline and throughout the study, offering an opportunity to create a program project to investigate hypotheses related to the biology underlying the PCPT findings as well as the etiology and risk of prostate cancer. The transition of the randomized PCPT into this translational and epidemiologic scientific investigation required extensive planning and coordination. Five individual but interrelated projects were brought together with the underlying program theme of the genetic, metabolic, and environmental factors associated with the risks of overall and high-grade prostate cancer and how these factors affected the efficacy of finasteride in preventing cancer. All projects with serum-based measures use a single, shared, nested case-control sample of participants so that each subject provides a more complete biomarker and genetic profile for the evaluation of joint effects of these factors. Strengths of this program include the following: 1) the control group contains only men who are negative for biopsy-detected cancer, 2) the statistical methods to evaluate associations of risk factors with disease are shared across all projects, 3) the large number of cancer cases with fully characterized genetic, metabolic, and behavioral exposures, 4) a central pathology core histopathologically classified the prostate cancer, and 5) cancer cases identified during the PCPT reflect the characteristics of cases currently being detected in the prostate-specific antigen screening era, leading to contemporary and highly relevant results. This article describes the comprehensive methodology and multidisciplinary collaborations, both national and international, essential to a major risk-modeling research program. We provide a framework for doing collaborative research in an international setting structured around a common theme of a clinical trial.