Predictors of prostate cancer after initial diagnosis of atypical small acinar proliferation at 10 to 12 core biopsies

Objectives. To evaluate the factors that predict prostate cancer detection by means of 10 to 12 core repeat biopsies in patients with atypical small acinar proliferation (ASAP) results on initial biopsy. Methods. From 1998 to 2004, 110 of 127 patients (87%) with a diagnosis of ASAP were rebiopsied with the same technique plus additional biopsies on the ASAP site (12.6 +/- 1.1 cores [mean +/- standard deviation]). Each histologic slide was reviewed blindly by a single experienced pathologist, who also differentiated highly suspicious (ASAPH) and not highly suspicious (ASAPB) lesions for cancer. Results. On initial biopsy, a concomitant high-grade prostatic intraepithelial neoplasia (HGPIN) was present in 26 patients (23%) with ASAP. The overall cancer detection rate was significantly higher in patients who had ASAP associated with HGPIN (58%), compared with patients who had isolated ASAP (35%; P = 0.04). The cancer detection rate was not significantly higher in patients with ASAPH than in those with ASAFB (49% versus 33%, respectively; P = 0.11). In the group of patients who had isolated ASAP, the rate of cancer detection was significantly higher in patients who had a prostatic volume less than 50 mL (56%) than in patients with a prostatic volume of 50 mL or more (27%; P = 0.03). Conclusions. The cancer detection rate was significantly higher in patients with an ASAP associated with HGPIN on initial biopsy than in patients with isolated ASAP. In ASAP patients, the detection rate was lower for patients with a larger prostate than in those with a smaller prostate.