Clinical Factors Associated With Pathological Grade Group 1 Patients in D'Amico Intermediate-Risk Group Following Robot-Assisted Radical Prostatectomy: A Retrospective Multicenter Cohort Study in Japan (The MSUG94 Group).

INTRODUCTION: We aimed to examine the relationship between D'Amico intermediate-risk and pathological grade group 1 (pGG1) after robot-assisted radical prostatectomy (RARP). PATIENTS AND METHODS: In this retrospective multicenter cohort study, D'Amico intermediate-risk prostate cancer patients who did not receive neoadjuvant therapy, and underwent RARP at 10 institutions in Japan were examined for preoperative factors associated with pGG1. RESULTS: In total, we enrolled 1161 D'Amico intermediate-risk prostate cancer patients. The pGG1 and pGG ≥2 groups comprised 73 (6.3%), and 1088 (93.7%) cases, respectively. Biochemical recurrence-free survival (BCRFS) of the pGG1 group was equivalent to that of the D'Amico low-risk patients. Among the 3 D'Amico intermediate-risk factors (IRF), the pGG1-rate was 24% with prostate-specific antigen (PSA) of 10 to 20 ng/mL alone, and 30% with cT2b alone. Both groups had significantly higher pGG1-rates than other groups. Down-grading from biopsy GG ≥2 to pGG1 was relatively rare (3.9%). Patients with pGG1 were further stratified by prostate volume (PV) (cutoff, 40 cc) among patients with one IRF and PSA of 10 to 20 ng/mL. Patients with one IRF, PSA of 10 to 20 ng/mL, and PV >40 cc had a relatively good BCRFS similar to that of the D'Amico low-risk group. CONCLUSION: Among intermediate-risk prostate cancer patients, those with pGG1 have a good prognosis. Downgrading from biopsy GG ≥2 is rare, and definitive treatment may be recommended for patients with biopsy GG ≥2. Patients with one IRF, PSA of 10 to 20 ng/mL, and PV >40 cc who are eligible for RARP may be candidates for active surveillance.