Cancer-Specific Mortality Differences in Specimen-Confined Radical Prostatectomy Patients According to Lymph Node Invasion

It is not clear whether cancer specific mortality (CSM) differences exist in radical prostatectomy (RP) treated prostate cancer (PCa) patients with specimen-confined (pT2) stage according to presence of lymph node invasion (LNI). Overall, 32,258 patients with pT2 PCa at RP + LND were identified. Of these, 448 (1.4%) patients harbored LNI. In multivariable Cox-regression models pN1 independently predicted higher CSM (HR: 4.4, P < .001). In sensitivity analyses addressing pT2 pN1 patients, 5-year CSM-free estimates were 99.3, 100 and 84.4% for ISUP GG 1-3 vs. 4 vs. 5, respectively ( P < .001). These findings might be of value for clinical decision making, as well as for individual patient counseling.Purpose: To test cancer-specific mortality (CSM) differences in specimen-confined (pT2) prostate cancer (PCa) at radical prostatectomy (RP) with lymph node dissection (LND) according to lymph node invasion (LNI). Methods: RP + LND pT2 PCa patients were identified (surveillance, epidemiology, and end results 2010-2015). CSM-FS rates were tested in Kaplan-Meier plots and multivariable Cox-regression (MCR) models. Sensitivity analyses respectively addressing patients with 6 or more lymph nodes analyzed and pT2 pN1 patients were performed. Results: Overall, 32,258 patients with pT2 PCa at RP + LND were identified. Of these, 448 (1.4%) patients harbored LNI. Five-year CSM-free estimates were 99.6% for pN0 vs. 96.4% for pN1 (P < .001). In MCR models, pN1 (HR: 3.4, P < .001) independently predicted higher CSM. In sensitivity analyses addressing patients with 6 or more lymph nodes analyzed (n = 15,437), 328 (2.1%) pN1 patients were identified. In this subgroup, 5-year CSM-free estimates were 99.6% for pN0 vs. 96.3% for pN1 (P < .001) and, in MCR models, pN1 independently predicted higher CSM (HR: 4.4, P < .001). In sensitivity analyses addressing pT2 pN1 patients, 5-year CSM-free estimates were 99.3, 100 and 84.8% for ISUP GG 1-3 vs. 4 vs. 5, respectively (P < .001). Conclusions: In patients with pT2 PCa a small proportion harbor LNI (1.4%-2.1%). In such patients, CSM rate is higher (HR 3.4-4.4, P < .001). This higher CSM risk seems to virtually exclusively apply to ISUP GG5 patients (84.8% 5-year CSM-free rate).