Increased utilization of external beam radiotherapy relative to cystectomy for localized, muscle-invasive bladder cancer: a SEER analysis.

ABSTRACT

OBJECTIVE: To assess recent utilization patterns of radiotherapy (RT) relative to cystectomy for muscle-invasive bladder cancer (MIBC) and evaluate survival trends over time in patients receiving RT. MATERIALS AND METHODS: The surveillance, epidemiology, and end results program (SEER) was used to identify patients diagnosed between 1992 and 2013 with localized MIBC. Patients with a prior history of non-bladder malignancy, who received no treatment, or did not have available treatment information, were excluded. Treatment utilization patterns were assessed using Cochran-Armitage tests for trend, and patient characteristics were compared using chi-square tests. Overall survival (OS) and cause-specific survival (CSS) were estimated using the Kaplan-Meier method. All-cause (ACM) and cause-specific mortality (CSM) were evaluated with multivariable Cox proportional hazards regression. RESULTS: Of 16175 patients analyzed, 11917 (74%) underwent cystectomy, and 4258 (26%) were treated with RT. Patients who received RT were older (median age 79 vs. 68, P < 0.01). Over time, the proportion of patients receiving RT relative to cystectomy increased (24% 1992-2002 vs. 28% 2003-2013, P < 0.01), despite median patient age throughout the study period remaining unchanged (71 for each 1992-2002 and 2003-2013, P = 0.41). For RT, compared with patients diagnosed earlier, those diagnosed from 2010-2013 showed improved OS (64% vs. 60% at 1 year, P < 0.01; 38% vs. 29% at 3 years, P < 0.01) and CSS (71% vs. 67% at 1 year, P = 0.01; 51% vs. 40% at 3 years, P < 0.01). On multivariable analysis, diagnosis from 2010-2013 was associated with a lower estimated risk of ACM (hazard ratio 0.77; 95% confidence interval 0.66-0.89, P < 0.001) and CSM (hazard ratio 0.81; 95% confidence interval 0.67-0.97, P = 0.02). CONCLUSION: Utilization of RT for localized MIBC increased relative to cystectomy from 1992 to 2013, despite the median age of treated patients remaining unchanged. More recent survival outcomes for patients receiving RT were improved, supporting continued use of bladder preservation strategies utilizing RT.