Clinically Significant Prostate Cancer in Men With High-Grade Intraepithelial Prostatic Intraepithelial Neoplasia or Atypical Small Acinar Proliferation

Abstract

The clinical management of Atypical Small Acinar Proliferation (ASAP) and High-Grade Prostate Intraepithelial Neoplasia (HGPIN) varies significantly. The aim of this study was to characterize the incidence and natural history of ASAP and HGPIN lesions to optimize follow-up strategies. A retrospective analysis of patients at a VA Medical Center who underwent a prostate needle biopsy between 1988 and 2017 was performed. The pathological lesions were grouped as ASAP, HGPIN, and ASAP & HGPIN. The primary outcome was the incidence of clinically significant prostate cancer (csPCa) defined as grade group ≥2 prostate cancer. Of 6104 patients screened, 312 patients included having ASAP (n = 70, 1.1%), HGPIN (n = 222, 3.6%), or ASAP & HGPIN (n = 20, 0.3%). Follow-up biopsy was performed in 99.3% of patients. The incidence of prostate cancer in ASAP, HGPIN, or ASAP & HGPIN groups was 46.3%, 37%, and 68.4%, respectively (P = .03). However, the rate of csPCa was similar across the 3 groups (10.1% in ASAP, 10.3% in HGPIN, and 10.5% in ASAP & HGPIN, P = .6). The median time to cancer diagnosis was significantly shorter for patients with ASAP (2.8 years for ASAP, 4.9 years for HGPIN, and 1.5 years for ASAP & HGPIN, P = .001); however, there was no significant difference in time to diagnosis of csPCa between the various groups (P = .7). Both ASAP and HGPIN have a low risk of progression to csPCa. This, coupled with a prolonged time to any cancer diagnosis, suggests that immediate repeat biopsy might not be necessary among these patients.