High-grade prostatic intraepithelial neoplasia and atypical small acinar proliferation: predictive value for cancer in current practice.

In earlier studies, prostate cancer (PCa) has been reported to appear in 21% to 48% of subsequent biopsies for isolated high-grade prostatic intraepithelial neoplasia (PIN) and in 34% to 60% for isolated atypical small acinar proliferation suspicious for, but not diagnostic of, malignancy (ASAP). We report results of follow-up biopsies in a recent cohort of community practice patients who underwent biopsy for PSA abnormalities. The study group consisted of 336 men with initial diagnoses of PIN (n = 204), ASAP (n = 78), or both lesions (n = 54) who underwent at least one repeat biopsy. Mean follow-up intervals in months were 6.0 for PIN, 3.8 for ASAP, and 4.9 for PIN/ASAP. Follow-up PCa detection rates were 23%, 37%, and 33%, respectively. The predictive value of ASAP was significantly higher than that for PIN (P = 0.0188). In 23 PIN studies with chronologic midpoints in the early 1990s, follow-up PCa was detected in a mean of 36% of cases, whereas this value was 21% after the year 2000. In 13 ASAP studies, mean PCa detection on follow-up was 45% until 1996 and 39% from 1997 to present. PIN/ASAP predicted PCa in 33% of cases in our study, similar to ASAP alone (P = 0.65) and had a mean predictive value of 44% in the literature. Factors that may account for the decline in PIN predictive values include: 1) extended biopsy techniques that yield higher rates of initial cancer detection, 2) lower detection rate for the remaining small cancers that may accompany PIN, and 3) remaining PIN cases may lack concomitant cancer.