Reversibility of prostatic intraepithelial neoplasia: implications for chemoprevention.

High-grade prostatic intraepithelial neoplasia is the most likely precursor of prostatic adenocarcinoma, according to virtually all available evidence. It has a high predictive value as a marker for adenocarcinoma, and its identification in biopsy specimens of the prostate warrants further search for concurrent invasive carcinoma. Androgen deprivation therapy and radiation therapy decrease its prevalence and extent, suggesting a role in chemoprevention.