Atypical Intraductal Proliferation in Patients With Grade Group 1-2 or No Invasive Cancer on Prostate Biopsy: An Institutional Experience

Objectives Atypical intraductal proliferation (AIP) is an intraductal proliferation in which histologic features are more atypical than high-grade prostatic intraepithelial neoplasia but fall short of diagnostic criteria of intraductal carcinoma. We performed a retrospective review of patients with AIP and low-grade or no invasive cancer and correlated with follow-up and Decipher scores. Methods Prostate biopsies from 2016 to 2022 with AIP and no invasive carcinoma, Grade Group 1 (GG1, Gleason score 3 + 3 = 6) prostatic adenocarcinoma, or Grade Group 2 (GG2, Gleason score 3 + 4 = 7) prostatic adenocarcinoma were identified. Patients with concomitant intraductal carcinoma and/or ≥ GG3 were excluded. Decipher testing, PTEN staining, and subsequent biopsy/prostatectomy data were obtained from the medical record. Adverse features at prostatectomy were defined as ≥GG3, ≥pT3a, pN1, intraductal carcinoma, or Gleason pattern 5. Results There were 51 biopsies with AIP and no invasive cancer ( n = 5), GG1 ( n = 10), or GG2 ( n = 36) from 2016 to 2022. Of 18 patients who underwent subsequent biopsy, 6 (33%) had increase in Grade Group. Of 14 patients who underwent prostatectomy, 10 (71%) showed at least one adverse feature at prostatectomy. Twelve patients (10 GG2, 2 GG1) had Decipher testing. The median Decipher for the 10 GG2 biopsies was 0.53, corresponding to intermediate Decipher risk. The median Decipher for the 2 GG1 biopsies was 0.40, corresponding to low Decipher risk. Conclusions AIP in the absence of other high-risk features at biopsy may be a harbinger of subsequent adverse pathology on follow-up. AIP is an entity that may require more frequent active surveillance in the absence of other high-risk features.