Atypical small acinar proliferation (ASAP) on extended prostatic biopsies: Predictive factors of cancer detection on repeat biopsies

Objective: To evaluate the clinical and histopathologic factors that may help to predict cancer detection by means of extended repeated prostate needle biopsies in patients with atypical small acinar proliferation (ASAP) results on initial prostate biopsy. Materials and methods: from 1998 to September 2003, 105 out of 121 (86%) patients with a diagnosis of ASAP after a first set of 10 to 12 systematic biopsies, were rebiopsied using the same technique plus additional biopsies on the ASAP site (mean number of repeat biopsy samples, 12.6). The median time until a second and third biopsy was 7.04 months (95% confidence interval [CI], 5.5-8.5), and 13.3 months (95% CI, 8.8-17.7; 19 patients), respectively. Each histological slide was reviewed blindly by a single experienced pathologist (M.F.) who differentiated highly suspicious (ASAPH) and not highly suspicious (ASAPB) lesions for cancer. Results: On initial biopsy, a concomitant HGPIN was present in 18 patients (17%) with ASAP. The overall cancer detection rate in those who underwent two or three sets of biopsies was 39% (41/105); it was 35% (37/105) and 21% (4/19) in second and third biopsies, respectively. The overall cancer detection rate was higher in patients who had ASAP associated with HGPIN (50%) compared with patients who had isolated ASAP (37%) (p = 0.3). Statistical analysis showed that levels of prostate-specific antigen (PSA), PSA density, prostatic volume, digital rectal examination results, transrectal ultrasound findings, time until rebiopsy (less vs. more than 6 months), and histological level of suspicion were not significant predictors of prostate cancer at the time of rebiopsy. In particular, the cancer detection rate was not significantly higher in patients with ASAPH than those with ASAPB (49% vs. 33%, respectively; p = 0.11). In a univariate analysis, the mean prostate volume was statistically different in patients with cancer compared with those without (56.4±6.3 and 78.9±5.3 respectively; p = 0.009), but only in the group of patients who had isolated ASAP. In these patients, the rate of cancer detection was significantly higher in patients who had a prostatic volume less than 60 mL (56%) than in patients with a prostatic volume greater than or equal to 60 mL (27%) (p = 0.03). Conclusions: Patients with an initial ASAP diagnosis after extended biopsies had an overall cancer detection rate less than 40% after two sets of extended biopsy. ASAPH lesions did not indicate a significantly higher risk of cancer than ASAPB lesions on repeated extended biopsies. Despite the extended rebiopsy plus the additional biopsies targeted to the ASAP lesion, the detection rate was lower for patients with a larger prostate than those with a smaller prostate