Atypical small acinar proliferation (ASAP): Is a repeat biopsy necessary ASAP? A multi-institutional review.

BACKGROUND: Atypical small acinar proliferation (ASAP) occurs in approximately 5% of prostate biopsies. Approximately 30-40% of patients with ASAP may develop prostate cancer (PCa) within a 5-year period. Current guidelines recommend a repeat biopsy within 3-6 months after the initial diagnosis. Our objective was to examine the association between ASAP and subsequent diagnosis of high-grade PCa and to evaluate the need for immediate repeat biopsy.

METHODS: A retrospective multi-institutional review identified 264 patients who underwent prostate biopsy from 2000 to 2013 (Brown), 2008 to 2013 (University of Massachusetts) and 1994 to 2005 (Mayo) and were diagnosed with ASAP. Patients underwent transrectal ultrasound-guided biopsies for elevated PSA and/or abnormal digital rectal exam. Clinicopathologic features were assessed, including rates of subsequent PCa detection of any high-grade (Gleason 7-10) PCa. Comparison was made between those with subsequent PCa on repeat biopsy and those with benign repeat pathology.

RESULTS: All 264 patients included underwent repeat biopsy with a median follow-up of 5.4 years (interquartile range: 4.6, 6.7). Of these patients, 89 (34%) were subsequently diagnosed with PCa including 21 (8%) with high-grade PCa. Pre-biopsy PSA was higher among patients subsequently diagnosed with (6.7 vs 5.8, P<0.001). Of those diagnosed with subsequent PCa, 69/89 (78%) had less than or equal to Gleason 3+3 disease and only 15/89 (17%) had Gleason 7 and 6/89 (6%) revealed Gleason ⩾8-10. Radical prostatectomy was performed on 36/89 (40%) patients. Surgical pathology revealed 11 patients ⩾Gleason 8-10 PCa.

CONCLUSIONS: Although 34% of patients with an initial diagnosis of ASAP who had repeat biopsy were subsequently diagnosed with PCa only, only 22% (8% of the total cohort) were found to have high-grade disease. Higher PSA was associated with increased risk of identifying PCa on repeat biopsy. These findings suggest that immediate repeat biopsy may be omitted in the majority of men with ASAP.