Bladder only versus bladder plus pelvic lymph node chemoradiation for muscle-invasive bladder cancer

Area of Science:

• Oncology
• Radiation Oncology
• Urothelial Carcinomas

Background:

• Muscle-invasive bladder cancer (MIBC) is often treated with bladder-sparing chemoradiation therapy (CRT).
• The optimal radiotherapy target volume, either bladder-only (BO) or bladder plus pelvic lymph nodes (BPN), is not well-defined.
• Determining the ideal radiation volume is crucial for improving patient survival and treatment efficacy.

Purpose of the Study:

• To compare the overall survival (OS) of patients with muscle-invasive bladder cancer treated with either bladder-only (BO) or bladder plus pelvic lymph nodes (BPN) radiation volumes as part of chemoradiation therapy (CRT).
• To investigate whether the choice of radiation treatment volume impacts long-term survival outcomes in node-negative MIBC.
• To analyze trends in the utilization of BO versus BPN treatment volumes over time.

Main Methods:

• A retrospective analysis of 2,104 patients with cT2-4N0M0 urothelial cell carcinoma of the bladder treated with CRT from 2004 to 2016 was conducted using the National Cancer Database.
• Patients were categorized into two groups based on the radiotherapy target volume: bladder-only (BO) or bladder plus pelvic lymph nodes (BPN).
• Overall survival (OS) was compared using Kaplan-Meier analysis and multivariable Cox proportional hazards models. Sensitivity analyses were performed to assess the impact of clinical T stage and radiation modality. Annual trends in BO vs. BPN use were analyzed.

Main Results:

• A total of 578 patients received BO CRT and 1,526 received BPN CRT.
• The use of BPN increased significantly from 2004 to 2016 (66.9% to 76.8%).
• No significant difference in overall survival was observed between the BO and BPN groups at 5 and 10 years (log-rank P = 0.10). Multivariable analysis also showed no significant association between BPN and OS (adjusted HR 0.90, P = 0.09). Sensitivity analyses did not reveal differential effects based on T stage or radiation modality.

Conclusions:

• Increased utilization of pelvic lymph node radiation in the US for node-negative muscle-invasive bladder cancer may not translate to improved long-term survival outcomes.
• Current evidence suggests that bladder-only radiation volumes may be sufficient for selected patients, warranting further investigation.
• Prospective clinical trials, such as SWOG/NRG 1806, are essential for optimizing radiation treatment volumes in MIBC and establishing definitive guidelines.