Radiation-based Therapy for Muscle-invasive Bladder Cancer: Contemporary Outcomes Across Tertiary Centers

Background: Radiation therapy (RT) is an alternative to radical cystectomy (RC) for muscle-invasive bladder cancer (MIBC).

Objective: To analyze predictors of complete response (CR) and survival after RT for MIBC.

Design, setting, and participants: This was a multicenter retrospective study of 864 patients with nonmetastatic MIBC who underwent curative-intent RT from 2002 to 2018.

Outcome measurements and statistical analysis: Regression models were used to explore prognostic factors associated with CR, cancer-specific survival (CSS), and overall survival (OS).

Results and limitations: The median patient age was 77 yr and median follow-up was 34 mo. Disease stage was cT2 in 675 patients (78%) and cN0 in 766 (89%). Neoadjuvant chemotherapy (NAC) was given to 147 patients (17%) and concurrent chemotherapy to 542 (63%). A CR was experienced by 592 patients (78%). cT3-4 stage (odds ratio [OR] 0.43, 95% confidence interval [CI] 0.29-0.63; p < 0.001) and hydronephrosis (OR 0.50, 95% CI 034-0.74; p = 0.001) were significantly associated with lower CR. The 5-yr survival rates were 63% for CSS and 49% for OS. Higher cT stage (HR 1.93, 95% CI 1.46-2.56; p < 0.001), carcinoma in situ (HR 2.10, 95% CI 1.25-3.53; p = 0.005), hydronephrosis (HR 2.36, 95% CI 1.79-3.10; p < 0.001), NAC use (HR 0.66, 95% CI 0.46-0.95; p = 0.025), and whole-pelvis RT (HR 0.66, 95% CI 0.51-0.86; p = 0.002) were independently associated with CSS; advanced age (HR 1.03, 95% CI 1.01-1.05; p = 0.001), worse performance status (HR 1.73, 95% CI 1.34-2.22; p < 0.001), hydronephrosis (HR 1.50, 95% CI 1.17-1.91; p = 0.001), NAC use (HR 0.69, 95% CI 0.49-0.97; p = 0.033), whole-pelvis RT (HR 0.64, 95% CI 0.51-0.80; p < 0.001), and being surgically unfit (HR 1.42, 95% CI 1.12-1.80; p = 0.004) were associated with OS. The study is limited by the heterogeneity of different treatment protocols.

Conclusions: RT for MIBC yields a CR in most patients who elect for curative-intent bladder preservation. The benefit of NAC and whole-pelvis RT require prospective trial validation.

Patient summary: We investigated outcomes for patients with muscle-invasive bladder cancer treated with curative-intent radiation therapy as an alternative to surgical removal of the bladder. The benefit of chemotherapy before radiotherapy and whole-pelvis radiation (bladder plus the pelvis lymph nodes) needs further study.