SAN FRANCISCO — Locoregional recurrence after cystectomy for advanced bladder cancer is common and rarely salvageable. Now new findings show that many of those recurrences may be prevented with postoperative pelvic radiation. 

The findings, from the Bladder Adjuvant RadioTherapy (BART) trial, show that radiating the cystectomy bed and pelvic lymph nodes after surgery greatly reduced locoregional recurrences in patients with high-risk, locally advanced muscle-invasive bladder cancer — to 8% from 26% without radiotherapy. 

“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 principal investigator Vedang Murthy, MD, a radiation oncologist at Tata Memorial Hospital in Mumbai, India.

“Pelvic relapse can be devastating for patients — extremely painful and almost impossible to treat,” noted Murthy, who presented the findings at the American Society for Radiation Oncology 2025 annual meeting. “Our research shows that modern radiation therapy offers a safe way to prevent many of these recurrences and improve patients’ quality of life.” 

The trial randomized 153 patients with locally advanced muscle-invasive bladder cancer equally to either observation or radiation after cystectomy. Nearly all patients also received chemotherapy, primarily before surgery (71%). The radiation dose in the treatment arm was 50.4 Gy in 28 fractions over about 6 weeks. 

Patients were at high risk for recurrence: 62% had pT3-4 tumors, 41% had lymph node involvement, and 28% had variant histologies. 

Over a median follow-up of 47 months, 26% of patients in the observation arm had a locoregional recurrence vs only 8% in the radiotherapy arm (P = .006). Similarly, 2-year locoregional control was 76.4% with observation but 91.2% with radiation (P = .004). 

Two-year overall survival also favored radiation (68.1% vs 57%), but the finding was not statistically significant (P = .40) — probably because there weren’t enough patients in the trial, Murthy said. 

The findings do leave a “very key question” open, Murthy told Medscape Medical News. In the US, patients undergoing radical cystectomy would typically receive perioperative immunotherapy, particularly nivolumab, in addition to chemotherapy — and the potential effects of adding radiotherapy are unknown.

Because immunotherapy and radiation work in different ways — immunotherapy systemically to reduce metastases and radiation locally to prevent pelvic recurrences — their effects may be additive, Murthy said. 

That point was echoed by one of the study discussants, Brian Baumann, MD, a radiation oncologist at the University of Pennsylvania, Philadelphia. 

“I think the BART trial, showing the strong improvement in local recurrence-free survival and disease-free survival that approximates immunotherapy argues that [radiation] should also be a new standard of care, along with adjuvant immunotherapy,” Baumann said. “For optimal outcomes, I think the future is probably combining the two.” 

In the meantime, if US patients cannot get immunotherapy for whatever reason, Murthy and Baumann said radiation is now a valid alternative. 

BART used modern intensity-modulated radiation therapy. About 20% of patients had moderate gastrointestinal symptoms, which was the expected rate, and few had severe radiation side effects. No patient stopped radiation because of toxicity. Overall, 8.5% of patients in the radiation arm had severe late side effects vs 10.5% in the observation arm. 

About one-third of patients in both trial arms developed distant metastases, and Murthy acknowledged that most people with muscle-invasive bladder cancer ultimately die from distant metastases, not local recurrences. 

Still, he said, “whatever relapse we can reduce, we must reduce.” 

The trial was funded by Tata Memorial Centre. Murthy disclosed no conflicts of interest.