Incidence of Clinically Significant Prostate Cancer After a Diagnosis of Atypical Small Acinar Proliferation, High-grade Prostatic Intraepithelial Neoplasia, or Benign Tissue

Abstract

To assess the incidence of clinically significant and insignificant prostate cancer after an initial biopsy that revealed either atypical small acinar proliferation (ASAP), high-grade prostatic intraepithelial neoplasia (HGPIN), or benign tissue. We retrospectively identified patients diagnosed with ASAP, HGPIN, or benign tissue who had a repeat prostate biopsy within 1 year of diagnosis during 1987-2015. We compared the incidence of any prostate cancer and clinically significant prostate cancer (based on Gleason score, prostate-specific antigen (PSA), number of positive cores, and core volume) for each diagnostic group. A total of 17,016 biopsies were performed in 12,817 patients during 1987-2015. Among the 615 patients who had a repeat biopsy within 1 year of their first, 261 (42.4%), 208 (33.8%), and 146 (23.8%) had ASAP, HGPIN, or benign tissue on the initial biopsy, respectively. The second biopsy demonstrated significant differences in prostate cancer detection rates between these 3 groups (34.1%, 20.2%, and 15.8%, respectively; P <.001), with cancer detected significantly more often in the ASAP group relative to other groups (P <.001 vs benign and P = .001 vs HGPIN). The rates of clinically significant prostate cancer did not differ between groups (8.0%, 6.7%, and 4.1%, respectively, P = .31). On repeat biopsy, rates of clinically significant prostate cancer did not differ between patients initially diagnosed with ASAP, HGPIN, or benign tissue. Elevated rates of prostate cancer after a diagnosis of ASAP appear to be largely due to differences in the rate of clinically insignificant disease.