Association between radiation therapy to the recurrence sites and oncological outcomes in patients who experienced local recurrence and/or pelvic lymph node metastases after radical cystectomy: A multicenter retrospective study.

788 Background: Local recurrence and/or pelvic lymph node metastases after radical cystectomy (RC) are often observed in patients with muscle-invasive bladder cancer (MIBC). Although chemotherapy and immune checkpoint inhibitors are the main treatment strategies in such patients, radiation therapy (RT) to the recurrence sites might be one of the treatment options. However, its effects on oncological outcomes remain unclear. Methods: This multi-institutional retrospective study included 106 patients who experienced local recurrence and/or pelvic lymph node metastases without distant metastases after RC. Patients were divided into two groups: patients who were treated with RT to the recurrence sites (RT group) and without (non-RT group). Multivariable Cox-proportional hazards regression analyses were performed to evaluate the effects of RT on cancer-specific survival (CSS) and overall survival (OS) after recurrence. Results: The median age at recurrence was 72 years, and the median follow-up period after recurrence was 13 months. Of the 106 patients, 65 (61%) received neoadjuvant chemotherapy (NAC) and 30 (28%) were treated with RT after recurrence. CSS and OS were not significantly different between the two groups ( P = 0.569 and P = 0.456, respectively). In univariable analyses, NAC, pure urothelial carcinoma, tumor grade, and lymphovascular invasion were significantly associated with CSS. Similarly, NAC, pure urothelial carcinoma, tumor grade, lymphovascular invasion, and pathological lymph node involvement were significantly associated with OS. After adjustment for these confounding variables, RT to recurrence sites was not significantly associated with prolonged CSS and OS (Table). Conclusions: RT to recurrence sites might have no effects on oncological outcomes in patients who experienced local recurrence and/or pelvic lymph node metastases after RC. Multivariable analyses for CSS and OS. CSS Factor P value HR 95% CI NAC Received 0.080 0.649 0.400–1.053 Pure urothelial carcinoma Positive 0.059 0.577 0.326–1.022 Tumor grade Grade 3 0.644 1.167 0.606–2.247 LVI Positive 0.003 2.407 1.353–4.283 Radiation therapy Positive 0.244 0.735 0.438–1.234 OS Factor P value HR 95% CI NAC Received 0.030 0.552 0.323–0.944 Pure urothelial carcinoma Positive 0.113 0.574 0.289–1.141 Tumor grade Grade 3 0.694 0.868 0.428–1.759 LVI Positive 0.005 2.438 1.305–4.556 Pathological N stage ≥ pN1 0.328 1.372 0.728–2.584 Radiation therapy Positive 0.161 0.652 0.359–1.186