Clinical strategy of repeat biopsy in patients with atypical small acinar proliferation (ASAP)

Atypical small acinar proliferation (ASAP) occurs in approximately 5% of prostate biopsies. Approximately 30–40% of patients with ASAP have biopsy detectable prostate cancer (PCa) within 5 years. Current guidelines recommend a repeat biopsy within 3–6 months after the initial diagnosis. The aim of the present study was to examine the association between ASAP and subsequent diagnosis of clinically significant PCa (csPCa). The need for immediate repeat biopsy was also evaluated. We identified 212 patients with an ASAP diagnosis on their first biopsy at our institution between February 2006 and March 2018. Of these patients, 102 (48.1%) had at least one follow-up biopsy. Clinicopathologic features including rates of subsequent PCa and csPCa were assessed. Thirty-five patients subsequently underwent radical prostatectomy (RP). Their pathologic results were reviewed. csPCa was defined as the presence of Gleason score (GS) ≥ 3 + 4 in ≥ 1 biopsy core. Adverse pathology (AP) was defined as high-grade (primary Gleason pattern ≥ 4) or non-organ-confined disease (pT3/N1) after RP. Of 102 patients, 87 (85.3%), 13 (12.7%), and 2 (2.0%) had one, two, and three follow-up biopsies, respectively. Median time from the initial ASAP diagnosis to the 2nd follow-up biopsy and the last follow-up biopsy were 21.9 months (range 1–129 months) and 27.7 months (range 1–129 months), respectively. Of these patients, 46 (45.1%) were subsequently diagnosed with PCa, including 20 (19.6%) with csPCa. Only 2 (2.0%) patients had GS ≥ 8 disease. Five (4.9%) patients had number of positive cores > 3. Of 35 patients who subsequently underwent RP, seven (20%) had AP after RP and 17 (48.6%) showed GS upgrading. Of these 17 patients, the vast majority (16/17, 94.1%) had GS upgrading from 3 + 3 to 3 + 4. 45.1% of patients with an initial diagnosis of ASAP who had repeat prostate biopsy were subsequently diagnosed with PCa and 19.6% were found to have csPCa. Our findings add further evidence that after a diagnosis of ASAP, a repeat biopsy is warranted and that the repeat biopsy should not be postponed.