Validation of tertiary Gleason pattern 5 in Gleason score 7 prostate cancer as an independent predictor of biochemical recurrence and development of a prognostic model.

OBJECTIVE: To validate the biological and prognostic value of tertiary Gleason pattern 5 (TGP5) in patients with Gleason score 7 (GS 7) prostate cancer (PCa) and to develop a prognostic model to identify the high-risk group of patients with TGP5. MATERIAL AND METHODS: We retrospectively reviewed the data from 4,146 patients with localized (pT2-3 N0 M0) GS 7 PCa treated by radical prostatectomy (RP) without adjuvant therapy. The primary end point was biochemical recurrence (BCR), and the secondary one was to build a bootstrap-corrected multivariable Cox model. RESULTS: Of the 4,146 patients, 416 (10%) had a TPG5 in the RP specimen. TGP5 was associated with BCR in both univariable and multivariable analyses that adjusted for the effects of standard pathological features (P<0.001). A prognostic model based on preoperative prostate-specific antigen levels (<10 vs.≥10ng/ml), primary and secondary Gleason pattern (3+4 vs. 4+3), pathological tumor category (pT2/pT3a vs. pT3b), and surgical margin status (R0 vs. R+) stratified patients with a discrimination of 72.2%. Patients in the low-risk group had a 5-year BCR-free survival rate of 76.3% compared with only 18.5% for those in the high-risk group (P<0.001). CONCLUSIONS: Knowledge of TGP5 improves our prognostication of patients with GS 7 PCa treated with RP. We developed a statistical tool to help identify the patients with TGP5 who are at the highest risk of BCR after RP, thereby helping with the clinical decision making regarding adjuvant trials and follow-up scheduling.