Prevention of local symptoms in muscle invasive bladder cancer patients: clinical significance of local radiation therapy.

PURPOSE: To evaluate the significance of local radiation therapy (LRT) for prevention of local symptoms (LSs) caused by muscle-invasive bladder cancer (MIBC). METHODS: We retrospectively reviewed the clinical records of 133 patients from 13 hospitals. MIBC patients with or without metastases who were treated with LRT alone from January 2015 through December 2020 were enrolled. Exclusion criteria were urinary diversion (UD) prior to LRT, non-MIBC, or lack of clinical information. LSs were defined as hematuria requiring invasive treatment or transfusion, UD after LRT, bladder tamponade, and opioid use for bladder pain. RESULTS: One hundred fourteen patients were finally enrolled in the study. During the median follow-up period of 13.5 months, 30 patients (26.3%) had LSs. Risk factors of LSs in multivariate analysis were a prior history of non-MIBC (NMIBC) (hazard ratio [HR] 2.99; 95% confidence interval [CI], 1.36 to 6.56; P < 0.01), radiation dose of less than 50 Gray (Gy) (HR 3.99; 95% CI, 1.80 to 8.82; P < 0.01), and tumor stage 3 or more (HR 2.43; 95% CI, 1.14 to 5.21; P = 0.02). Risk factors of overall survival (OS) in multivariate analysis were being female (HR 3.32; 95% CI, 1.68 to 6.58; P < 0.01), an age-adjusted Charlson Comorbidity index of 6 or more (HR 2.19; 95% CI, 1.18 to 4.10; P = 0.01), distant metastases (HR 3.20; 95% CI, 1.39 to 6.58; P < 0.01), and tumor size of 40 mm or more (HR 2.38; 95% CI, 1.34 to 4.52; P < 0.01). Toxicity (all grades) occurred in 40.4% of the patients, 4.8% with grade 3 or more and 95.2% with lower grades. CONCLUSIONS: We determined the risk factors for LSs in MIBC patients treated with LRT alone. An escalated-dose of 50 Gy or more may contribute to prevention of LSs caused by MIBC. Thus, dose-escalated LRT for MIBC patients who can expect favorable survival may be a good option to avoid future annoying LSs.