Radical radiotherapy using volumetric-modulated arc therapy for treating bladder and pelvic lymph nodes in locally advanced bladder cancer: A retrospective single-center study

Abstract

The prognosis of patients with muscle-invasive bladder cancer (MIBC) and pelvic nodes remains poor. We developed a novel radiotherapy (RT) protocol using volumetric-modulated arc therapy (VMAT) to treat bladder and locoregional nodes in MIBC. This study explores the safety, efficacy, and development of the VMAT protocol. Between June 2020 and August 2024, a total of 17 patients were treated using the novel VMAT protocol. The treatment regimen consisted of 57.5 Gy in 23 fractions to the bladder and 46 Gy in 23 fractions to the pelvic nodes. The present study reports on various parameters, including patient-related, disease-related, and treatment-related characteristics, along with toxicity profiles and long-term outcomes (response rates, nature of progression, and survival). The RT protocol was well tolerated, with 15 patients (88%) completing treatment as planned. Most acute toxicities were grade 1 or 2. One patient (6%) experienced a grade 3 acute toxicity (pain and local discomfort), while two patients (12%) experienced grade 3 late toxicity (colovesical fistula and severe radiation-induced cystitis). Following treatment, 12 patients (71%) had a response or a stable disease. Two patients (12%) developed local recurrence, six (35%) developed metastatic relapse, and nine patients (53%) showed no progression. The median progression-free survival was 15.8 months (95% confidence interval [CI]: 12.4 - 64.6), while the median overall survival was 23.1 months (95% CI: 13.6 - 64.6). This study has several limitations, primarily due to its retrospective design and small patient cohort. Furthermore, there was considerable variability in histology, fitness scores, and concomitant chemotherapy treatment. Nonetheless, the findings demonstrate the safety and feasibility of the VMAT protocol for treating the bladder and pelvic nodes in locally advanced MIBC, and they provide a rationale for future prospective studies to further evaluate the role of pelvic RT in this population.

Keywords

Bladder cancer / Radiation therapy / Chemotherapy