Introduction: To report the incidence and characteristics of cancer following a diagnosis of atypical small acinar proliferation (ASAP) and comment on current clinical practice recommendations.
Materials and methods: We reviewed patients that underwent prostate biopsy between 2008 and 2013 at a single institution. Men with ASAP without previous cancer were included. Clinicopathologic features including prostate-specific antigen (PSA), presence of ASAP or cancer, tumor volume, number of involved cores, and Gleason score were analyzed in men that received a repeat prostate biopsy.
Results: Of 1450 men, ASAP was found in 75 (5%) patients. Repeat biopsy was performed in 49 (65%) patients. Fifteen (31%) were diagnosed with cancer, 10 (20%) with ASAP, and 24 (49%) were benign. PSA, age, and number of cores with ASAP were not associated with cancer. Gleason 6 disease was diagnosed in 12 (80%) patients. Gleason ≥ 7 cancer was found in 3 patients, or 6% of all patients with a repeat biopsy. The average linear amount of tumor was 3.2 mm, and the average tumor volume was 14.2%.
Conclusion: In a contemporary prostate biopsy series, the incidence of ASAP was 5%. Among men with ASAP, incidence of cancer at repeat biopsy was 31%, with the overwhelming majority being low grade and low volume. Patients with ASAP may not require repeat biopsy within 6 months in the appropriate clinical context.