SURVIVAL IN ADJUVANT VS SALVAGE RADIATION THERAPY IN PATHOLOGICAL NODE POSITIVE PROSTATE CANCER PATIENTS: A MULTICENTRIC STUDY

INTRODUCTION AND OBJECTIVE: To compare metastasis-free survival (MFS), CRPC-progression free survival (CRPC-PSF) and overall survival (OS) rates between adjuvant (adj) vs. salvage (Salv.) radiotherapy (RT) in pathological node positive (pN1) prostate cancer (PCa) patients. METHODS: We relied on a multicentric database of 92 consecutive pN1 patients from 16 Academic institutions, of whom 72 (77%) vs. 22 (23%) were treated with primary AdjRT vs SalvRT, respectively. Kaplan-Meier plots and Cox regression models tested the effect of AdjRT vs SalvRT on CRPC-PFS, MFS, and OS. All analyses were adjusted for D’Amico risk group, percentage of positive lymph nodes at final pathology, and administration of androgen deprivation therapy (ADT). RESULTS: Overall, no statistically or clinically relevant differences were recorded between AdjRT vs SalvRT in age (medians 66 vs 66 years), PSA at diagnosis (medians 25 vs 25.5 ng/mL), biopsy grade group, D’Amico classification, extension of lymph node dissection and features at final pathology, including percentage of positive lymph nodes (all p>0.2). 5-year MFS, CRPC-PFS, and OM were respectively 77 vs 49% (p=0.15), 91% vs 89% (p=0.13), and 91 vs 100% (p=0.25) in AdjRT vs SalvRT. After Cox regression analysis, when compared to AdjRT, SalvRT yielded HR of 6.65 (95% CI 0.64-68.98, p=0.1) for CRPC-PFS, 3.80 (95% CI 1.11-12.99, p=0.03) for MFS, and 0.26 (95% CI 0.02-3.77, p=0.3) for OS, after adjustment for D’Amico risk, percentage of positive lymph nodes and administration of ADT. CONCLUSIONS: Our study suggests that despite AdjRT might offer better MFS, it provides equal OS outcomes compared to SalvRT, even after adjustment for adverse clinical and pathologic features and ADT. Therefore, both AdjRT and SalvRT can be considered as viable options for the treatment of pN1 PCa patients.