Purpose: High grade prostatic intraepithelial neoplasia is considered the most likely precursor of prostatic adenocarcinoma. However, the natural history and predictive value of prostatic intraepithelial neoplasia for cancer are unknown.
Materials and methods: To examine the predictive value of high grade prostatic intraepithelial neoplasia, we conducted a retrospective clinic based comparative study of 100 patients with high grade prostatic intraepithelial neoplasia and 112 without prostatic intraepithelial neoplasia on needle biopsies matched for digital rectal examination findings, patient age and serum prostate specific antigen level. Only patients who had 1 or more followup biopsies were included.
Results: Adenocarcinoma was identified in 35% of subsequent biopsies from patients with prostatic intraepithelial neoplasia, compared with 13% of control biopsies. The likelihood of finding cancer increased as the interval from initial biopsy increased. High grade prostatic intraepithelial neoplasia, patient age and serum prostate specific antigen concentration were jointly highly significant predictors of cancer, with prostatic intraepithelial neoplasia providing the highest risk ratio of 14.93 (95% confidence intervals 5.6 to 39.8). No other candidate predictor was significant, including digital rectal examination findings, transrectal ultrasound results, amount of prostatic intraepithelial neoplasia on biopsy and architectural pattern of prostatic intraepithelial neoplasia.
Conclusions: These results indicate that the presence of high grade prostatic intraepithelial neoplasia on needle biopsy is strongly predictive of carcinoma. Prostatic intraepithelial neoplasia should be reported in needle biopsies and biopsy repeated. These finding support the hypothesis that prostatic intraepithelial neoplasia is a precursor of prostate cancer.