Prognostic differences among Grade Group 4 subgroups in robotic-assisted radical prostatectomy.

Area of Science:

• Urologic Oncology
• Pathology
• Surgical Oncology

Background:

• The International Society of Urological Pathology (ISUP) Grade Group 4 (GG 4) is a critical prognostic category for prostate cancer (PCa).
• Subgroup analysis within GG 4 may refine risk stratification for patients undergoing treatment.

Purpose of the Study:

• To investigate oncological outcome differences among International Society of Urological Pathology Grade Group 4 (GG 4) subgroups in Japanese prostate cancer (PCa) patients.
• To determine if pathological Gleason scores (GS) of 3+5, 4+4, and 5+3 within GG 4 predict distinct biochemical recurrence (BCR) rates after robotic-assisted radical prostatectomy (RARP).

Main Methods:

• Retrospective multicentre cohort study of 298 Japanese PCa patients with GG 4 tumors undergoing RARP.
• Analysis of pre- and post-operative variables, focusing on biochemical recurrence (BCR)-free survival (BCRFS) across pathological GS subgroups (3+5, 4+4, 5+3).
• Multivariate analysis to identify independent risk factors for BCRFS.

Main Results:

• The 3-year BCRFS rate was 74.5% overall. Significant differences were observed among GG 4 subgroups: 93.8% for GS 3+5, 71.9% for GS 4+4, and 50.0% for GS 5+3 (P=0.01).
• Multivariate analysis identified pathological GS, PSA levels, pathological T and N stage, and surgical margins as independent risk factors for BCRFS.
• Patients with GS 4+4 and 5+3 had significantly higher BCR risk compared to GS 3+5.

Conclusions:

• Pathological Gleason score 4+4 and 5+3 are associated with worse BCRFS than 3+5 in localized PCa patients treated with RARP.
• Pathological GS 3+5 may be overestimated within the current GG 4 classification.
• Considering both primary and secondary Gleason scores is crucial for accurate BCR risk stratification after RARP.