Dose-Escalated Radiation Therapy as Primary Treatment for Residual Bladder Cancer After Transurethral Resection

Purpose: The aim of this study was to determine whether escalating the local radiation dose can improve the outcome of residual bladder cancer after transurethral resection of bladder tumor without increasing treatment-related toxicity. Methods and Materials: The treatment plans and medical records of patients with bladder cancer treated with curative-intent radiation therapy between 2008 and 2020 were reviewed. Those who had residual tumors in the computed tomography simulation images were included. A cumulative radiation dose higher than 6600 cGy was defined as dose escalation. The effect of dose escalation on 3-year locoregional control, progression -free survival, and overall survival was evaluated. Results: A total of 149 patients with residual tumors were identified. The median follow-up period was 27.5 months. Among them, 51 patients received an escalated radiation dose, and 98 received a standard dose in the residual tumor area. Patients in the dose-escalation group had higher 3-year locoregional control (65.6% vs 27.8%; P < .001) and progression -free survival (42.6% vs 18.2%; P < .001) than the standard -dose group. Overall survival also showed a trend favoring the dose-escalation group (54.9% vs 36.2%; P = .059). In the multivariate analyses, the differences between the dose-escalation and standard -dose groups were significant in terms of locoregional control (hazard ratio, 0.32; CI, 0.18-0.59; P = <.001) and progression -free survival (hazard ratio, 0.51; CI, 0.32-0.82; P = .005). There was no statistical difference in acute and chronic treatment-related toxicities between the 2 groups. Conclusions: The outcome of residual bladder cancer after transurethral resection of bladder tumor could be improved by doseescalated radiation therapy.