Target populations and strategies for chemoprevention trials of prostate cancer.

Chemoprevention trials usually target healthy populations and employ non-toxic chemicals in an effort to eliminate, reduce, or reverse premalignant lesions or early cancer. Recent efforts have been directed at short-term Phase II trials which rely on changes in surrogate endpoint biomarkers rather than cancer incidence reduction as an endpoint. Chemopreventive agents are chosen that are likely to produce a modulating effect on one or more biomarkers in prostate cancer, including extent and grade of morphometric, genetic, proliferative, differentiative, and regulatory biomarkers. Five target populations appear to have the greatest promise in chemoprevention trials for prostate cancer: (1) Patients with high-grade prostatic intraepithelial neoplasia, a microscopic lesion which is the likely precursor of some prostate cancers; (2) patients with early cancer treated by watchful waiting; (3) patients with cancer waiting for prostatectomy; (4) men at high risk of developing prostate cancer; and (5) men from the general population (normal risk of prostate cancer).