Atypical Small Acinar Proliferation and High Grade Prostatic Intraepithelial Neoplasia: Should We Be Concerned? An Observational Cohort Study with a Minimum Follow-Up of 3 Years

Introduction: Atypical small acinar proliferation (ASAP) and high grade prostatic intraepithelial neoplasia (HGPIN) are considered precancerous. We aimed to measure the rate of repeat biopsy and adenocarcinoma in patients with ASAP and HGPIN and identify any clinico-pathologic parameters at diagnosis of ASAP/HGPIN that are predictive of adenocarcinoma. Materials and Methods: Patients with a diagnosis of ASAP/HGPIN with no previous or concomitant cancer were identified. Prostate specific antigen (PSA) and magnetic resonance imaging (MRI) changes were monitored. Re-biopsy was at clinician discretion. Results: Nineteen were diagnosed with ASAP and 17 with HGPIN. Seven with ASAP (37%) and 6 with HGPIN (35%) underwent re-biopsy. Three (16%) with ASAP and 5 with HGPIN (29%) were diagnosed with adenocarcinoma. The difference in cancer detection rates between ASAP and HGPIN was not significant (p = 0.35). Five (14%) in total required definitive therapy for adenocarcinoma. Twenty-three (64%) did not undergo repeat biopsy. Parameters at diagnosis of HGPIN and ASAP, including PSA, prostate volume and PSA density, were compared between the cancer and non-cancer cohorts with none found to be predictive of adenocarcinoma. Conclusion: By monitoring PSA and MRI changes, we managed to spare re-biopsy in two-thirds of patients. Further evaluation is necessary to characterize a surveillance protocol in these populations.