Adjuvant radiotherapy reduces pelvic relapse risk in locally advanced MIBC

Data from the phase 3 BART trial (NCT02951325) show that adjuvant radiotherapy after radical cystectomy and chemotherapy improved locoregional failure-free survival (LRFS) and disease-free survival (DFS) without increasing severe late toxicity in patients with locally advanced muscle-invasive bladder cancer (MIBC).¹

The findings were presented at the American Society for Radiation Oncology (ASTRO) 67^th Annual Meeting by principal investigator Vedang Murthy, MD.

“This is one of the first studies and the largest randomized trial to show that postoperative radiation therapy can meaningfully reduce pelvic relapses in bladder cancer,” said Murthy, a professor and radiation oncologist at Tata Memorial Hospital in Mumbai, India, in a news release on the findings.² “Pelvic relapse can be devastating for patients—extremely painful and almost impossible to treat. Our research shows that modern radiation therapy offers a safe way to prevent many of these recurrences and improve patients’ quality of life.”

In total, the study included 153 patients randomly assigned to receive adjuvant radiotherapy at 50.4 Gy in 28 fractions (n = 77) or to observation (n = 76). In the treatment arm, 63 patients underwent adjuvant radiotherapy as planned, and 14 patients (8 defaulted/refused radiotherapy, 4 had preradiotherapy progression, 2 had radiotherapy deemed unfeasible) were analyzed in the observation arm (n = 90).

All patients underwent radical cystectomy. Nearly all received chemotherapy before (71%) or after (20%) surgery.

At a median follow-up of 23 months, 37% of all patients had disease recurrence, and 18% had locoregional recurrences. Locoregional recurrences occurred in 8% of patients in the radiotherapy arm vs 26% of patients in the observation arm (P = .006).

At 2 years, LRFS was significantly improved in the radiotherapy arm, with a rate of 87.1% with radiotherapy vs 76% with observation (HR, 0.43; 95% CI, 0.20 to 0.96; P = .04). Patients in the radiotherapy arm also showed improved 2-year DFS, with a rate of 71.6% vs 58.7% in the observation arm (HR, 0.62; 95% CI, 0.36 to 1.05; P = .07).

Further, 2-year bladder cancer-specific survival was 79.6% in the radiotherapy arm vs 65.0% in the observation arm (HR, 0.59; 95% CI, 0.33 to 1.10; P = .09). Two-year overall survival was 70.4% vs 57.4%, respectively (HR, 0.78; 95% CI, 0.49 to 1.26; P = .31).

Findings on the safety of adjuvant radiotherapy were previously presented at ASTRO 2024.³ According to the authors, the rate of severe adverse events (AEs; grade 3) was low. Overall, 1.6% of patients in the radiotherapy arm vs 4.2% of patients in the observation arm experienced a grade 3 AE (P = .34). Grade 2 AEs were reported in 17.5% of patients in the radiotherapy arm vs 1.1% of patients in the observation arm (P < .001). These mainly included diarrhea/enteritis or proctitis, according to the authors.

Additionally, grade 3 to 4 toxicity occurred in 8.4% of patients in the radiotherapy arm vs 10.5% of patients in the observation arm (P = .62).

Based on these findings, the authors concluded that radiotherapy after cystectomy in patients with a high risk of recurrence is safe using modern techniques. Murthy explained that this approach “can be implemented in most [radiotherapy] centers without extra resources/equipment.”

“BART shows that modern radiation techniques allow us to deliver highly targeted treatment with fewer complications than in the past,” Murthy concluded in the news release.² “Radiation therapy is already used safely after surgery for gynecologic cancers in the same anatomically complex region, suggesting it could also become a standard option for high-risk bladder cancer following cystectomy.”

He also suggested that these results could open the door for exploration of other approaches in this setting, including combination radiation and immunotherapy.

“The 2 treatments act differently, with distinct functions and [adverse] effect profiles, and there’s no reason we shouldn’t be combining them,” he said.

REFERENCES

1. Murthy V, Maitre P, Pal M, et al. Bladder adjuvant radiotherapy (BART): clinical outcomes from a phase III multicenter randomized controlled trial. Presented at: American Society for Radiation Oncology 67th Annual Meeting; September 27-October 1, 2025; San Francisco, CA. Abstract 2.

2. Radiation therapy after surgery safely reduces pelvic relapse risk from locally advanced, muscle-invasive bladder cancer. News release. American Society for Radiation Oncology. September 29, 2025. Accessed October 3, 2025. https://www.astro.org/news-and-publications/news-and-media-center/news-releases/2025/radiation-therapy-after-surgery-safely-reduces-pelvic-relapse-risk-from-locally-advanced-mibc

3. Murthy V, Maitre P, Bakshi G, et al. Bladder adjuvant radiation therapy (BART): acute and late toxicity from a phase III multicenter randomized controlled trial. Int J Radiat Oncol Biol Phys. 2025;121(3):728-736. doi:10.1016/j.ijrobp.2024.09.040