Outcome Differences Between Subgroups of Favorable Intermediate Risk Prostate Cancer After Radical Prostatectomy.

OBJECTIVE

Grade Group (GG) 1 disease is known to have low metastatic potential, but in the D'Amico risk stratification systems a GG1 tumor with prostate-specific antigen (PSA) of 10-20 ng/mL qualifies as intermediate risk (IR). We hypothesized that GG1 tumors are heterogenous and evaluated oncologic outcomes after prostatectomy.

METHODS

We performed a retrospective analysis of men undergoing robot-assisted radical prostatectomy (RARP) from July 2003 to June 2023. Patients met FIR criteria if biopsy results were GG1 with PSA 10-20 ng/mL (GG1-FIR), or if biopsy GG2 was the only IR feature (GG2-FIR). Primary endpoints were overall survival (OS); secondary endpoints were biochemical recurrence-free survival (BCRFS), postoperative upgrading, and time to radiotherapy. Analyses utilized Kaplan-Meier estimates with Cox models to compare outcomes between the FIR subgroups. Sensitivity analyses compared FIR subgroups with a low-risk cohort.

RESULTS

Of 2703 patients undergoing RARP, 553 (13.4%) met FIR criteria with 103 (18.6%) being GG1-FIR and 450 (81.4%) GG2-FIR. The primary analysis showed no difference in long-term oncologic outcomes. At 10 years, OS was 80.9% for GG1-FIR and 81.5% for GG2-FIR, declining to 62.2% and 69.5%, at 15 years (HR = 0.8, 95% CI 0.5-1.5; p = 0.63). BCRFS at 10 and 15 years was 87.5% and 84.2% for GG1-FIR vs. 89.8% and 81.2% for GG2-FIR (HR = 0.7, 95% CI 0.3-1.7; p = 0.54). Time to radiotherapy was comparable (HR = 0.70, 95% CI 0.36-1.33; p = 0.27). Upstaging, or pathologic ≥pT3 rates, were 24.3% vs. 30.4% (p = 0.21) and nodal positivity 3.3% vs. 2.1% (p = 0.64). In sensitivity analyses, GG1-FIR had similar OS (HR = 1.60, 95% CI 0.94-2.70) but worse BCRFS (HR = 2.56, 95% CI 1.22-5.38) compared with 1242 low-risk patients.

CONCLUSIONS

Patients with FIR tumors had similar long-term oncologic outcomes after RARP. However, GG1 tumors behaved differently across the PSA spectrum. When PSA is high, outcomes mirror clinically significant disease.