Incidence of high-grade prostatic intraepithelial neoplasia in sextant needle biopsy specimens

There is scant literature on the frequency of high-grade prostatic intraepithelial neoplasia (PIN) in needle biopsy specimens. These data have implications as to how often pathologists should be expected to diagnose these lesions on needle biopsy and impact on the feasibility of cancer chemoprevention trials for prostate cancer.

We reviewed 439 consecutive 18-gauge sextant needle biopsy specimens from the Johns Hopkins Hospital.

Based on the pathology reports, high-grade PIN was recorded in 12 (2.7%) of the cases and was confirmed upon review. Following review of the slides, unequivocal high-grade PIN was found in an additional 6 cases. There were 6 other cases where the findings were borderline between high- and low-grade PIN, but which were believed to be more consistent with high-grade PIN. Considering these latter cases in conjunction with the unequivocal cases of high-grade PIN, the incidence of high-grade PIN was 5.5% (24 of 439).

Recognizing that approximately 50% of men with high-grade PIN on needle biopsy will be found to have carcinoma on repeat biopsy, the management of high-grade PIN on biopsy will only apply to 50% of the men initially discovered with this finding. If only 2.75% of men who are biopsied eventually need therapy for high-grade PIN on needle biopsy, the number of cases needed to study the decrease of high-grade PIN following chemoprevention might be prohibitively high. If the incidence of high-grade PIN on needle biopsy requiring therapy is only 2.75%, it may also not be worthwhile developing large trials to investigate various treatment regimens for high-grade PIN found on biopsy.