Rate of Gleason 7 or higher prostate cancer on repeat biopsy after a diagnosis of atypical small acinar proliferation

Limited information is known about the clinical significance of cancers diagnosed upon repeat biopsy for the indication of atypical small acinar proliferation (ASAP). With increasing concern regarding overdiagnosis and overtreatment of prostate cancer, and the reported rise in infectious complications related to prostate biopsy, we examined the outcomes of patients rebiopsied for a diagnosis of ASAP.Methods:Clinical, pathologic and outcomes data of patients diagnosed with ASAP on prostate biopsy at our institutions between 2000 and 2010 were abstracted through chart review. Statistical analyses included Fisher's exact and the two-sample Wilcoxon rank sum tests. Logistic regression evaluated risk factors for the probability of cancer following a diagnosis of ASAP.Results:A total of 349 patients met the inclusion criteria with median follow-up of 4.4 years. Median age was 65.3 years with a median PSA of 5.3 ng ml^-1. Of men diagnosed with ASAP, 250/349 (71.6%) had a repeat biopsy within 1 year with 94/246 (38.2%) demonstrating prostate cancer; only 26/245 (10.6%) had ≥Gleason 7 disease. Of men diagnosed with ASAP, 284/349 (81.4%) underwent biopsy at some time during follow-up. Prostate cancer was diagnosed in 132/279 (47.3%) of these men, 48/278 (17.3%) with ≥Gleason 7 disease. Multivariate analyses suggested that older age, no previous biopsy and PSA density were predictive of cancer on repeat biopsy within 1 year from ASAP. Univariate analysis revealed PSA density was associated with the presence of ≥Gleason 7 disease at 1 year and any time after a diagnosis of ASAP.Conclusions:The overall rate of intermediate-and high-grade prostate cancer found on repeat biopsy for ASAP is low. Further investigation into ways to further risk stratify these men may be warranted. However, until such tests become available, repeat biopsy of men diagnosed with ASAP remains prudent.