Rate of clinically significant prostate cancer on repeated biopsy after a diagnosis of atypical small acinar proliferation

Introduction: Current guidelines recommend repeat biopsy within 3-6 months for the diagnosis of atypical small acinar proliferation (ASAP) on prostate biopsy. Objectives: We aimed to evaluate the rate of progression of ASAP to clinically significant prostate cancer on repeat biopsy specimens and determine prognostic factors associated with progression. Patients and Methods: In a retrospective study we reviewed data of patients who had a prostate biopsy in our institution from March 2014 to March 2018. Gleason grade group (GGG) was conducted for pathology reporting. Logistic regression analysis was conducted for statistical analysis. Results: A total of 981 patients were identified of which 117 (12%) of them had a diagnosis of ASAP on their index biopsy. Out of these 16 (14%) patients underwent re-biopsy. Baseline clinicopathologic factors included a median age of 61 years, median pre-biopsy prostate-specific antigen (PSA) of 6.75 ng/mL and a mode of 1 core with ASAP. Median time interval between index and repeat biopsy was 10.5 months. The results of repeat biopsies were distributed across GGG system as follows; 12(75%) benign, 2 (12.5%) GG1, 1 (6.25%) GG2, and 1 (6.25%). We found no association between age, pre-biopsy PSA, and number of cores with ASAP, and progression of ASAP to clinically significant prostate cancer. Conclusion: Our study showed that patients with a diagnosis of ASAP are more likely to have a benign pathology on repeat biopsy. This finding supports previous studies regarding rethinking current guidelines for utility of repeat biopsy in patients with the diagnosis of ASAP.