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

Objective: 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.

Materials And Methods: 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.

Results: 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).

Conclusion: 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.