Effect Of Concurrent Chemotherapy On Overall Survival In Elderly Bladder Cancer Patients Undergoing Radiotherapy: A Population-Based Analysis

e16000 Background: Randomized data demonstrate concurrent chemoradiotherapy (CRT) improves overall survival (OS) compared to radiotherapy alone (RT) in muscle invasive bladder cancer. However, patients ≥ 80 make up a small proportion of CRT trials, and the incremental benefit of CRT in elderly patients is unclear. We analyzed the National Cancer Database to estimate the improvement in OS with CRT compared to RT in this cohort. Methods: Patients ≥ 80 years old with cT2-4 N0-3 M0 muscle invasive bladder transitional cell carcinoma treated with RT or CRT were selected. The chi-squared test was used to compare clinical, treatment, and sociodemographic covariates between both groups. The Kaplan-Meier method was used to estimate OS, and univariate analysis (UVA) was performed using the log rank test to identify the impact of covariates on OS. Multivariable analysis (MVA) was performed using the Cox Proportional Hazards model, and included all covariates with p < 0.1 on UVA. Results: 474 patients treated with radiotherapy from 2004 to 2012 met eligibility criteria, 293 (62%) patients received RT and 181 (38%) patients received CCRT. Median age was 85 years (range: 80-90). CRT patients were younger (p < 0.001), were more likely to have Charlson-Deyo comorbidity score (CDCC) of 0 (p = 0.029) and radiation dose ≥ 60 Gy (p = 0.011). Median follow-up was 17 months. Overall 2-year OS was 40%. UVA revealed CRT (2-year OS 49% vs. 35%; p < 0.001), lower age (p = 0.032), lower t-stage (p = 0.043), lower n-stage (p = 0.037), and radiation dose ≥ 60 Gy (p < 0.001) were associated with improved OS. CDCC was not associated with OS (p = 0.112). MVA revealed CRT (Hazard ratio [HR], 0.68; 95% confidence interval [CI], 0.53 to 0.87; p = 0.002) and RT dose ≥ 60 Gy (HR 0.45; 95% CI, 0.36 to 0.57; p < 0.001) were associated with improved OS. T4 disease was associated with worse OS (HR 1.41; 95% CI, 1.03 to 1.94; p = 0.031). On sensitivity analysis, CCRT was still associated with improved OS when including CDCC in the MVA model. Conclusions: This is the largest series of elderly patients undergoing bladder cancer RT, and revealed that CRT is associated with improved OS, independent of CDCC. When possible, CCRT should be used in this population.