IMRT Matches Proton Therapy for Throat Cancer in Phase III Trial Announced at ASTRO 2025

A major clinical trial has found that two advanced forms of radiation therapy, intensity-modulated radiation therapy (IMRT) and proton beam therapy, provide equally strong quality-of-life outcomes for patients with locally advanced oropharyngeal cancer. Results were presented at the American Society for Radiation Oncology (ASTRO) 2025 Annual Meeting.

The TORPEdO trial, a randomized phase III study across the UK, showed no significant differences between the two treatments in swallowing function, feeding tube dependence, or overall quality of life one year after treatment. Both therapies delivered excellent tumor control with fewer long-term side effects than expected.

“We found no evidence of a difference in late patient-reported physical side effects or quality of life between proton beam therapy and IMRT, with contemporary IMRT performing better than we anticipated,” said David Thomson, MD, chief investigator of the trial and consultant clinical oncologist at The Christie NHS Foundation Trust. “Our results confirm that high-quality IMRT is a very good treatment for this disease.”

Key Findings

The study enrolled 205 patients with oropharyngeal squamous cell carcinoma (OPSCC), randomly assigning them to either proton therapy (136 patients) or IMRT (69 patients) combined with chemotherapy. At one year, feeding tube dependence was just 1.7% in both groups. Severe weight loss occurred in 18.2% of proton patients and 5.7% of IMRT patients, though overall differences were not statistically significant.

Patient-reported outcomes also showed no significant variation. Scores on widely used quality-of-life and swallowing function measures were nearly identical for both therapies. “IMRT performed better than expected based on historical data, and long-term feeding tube dependence was much lower than reported in previous trials,” Dr. Thomson noted.

Both treatments achieved high cancer control. The two-year overall survival rates were 94.6% for proton therapy and 95.3% for IMRT. While proton therapy reduced radiation exposure to nearby salivary and swallowing structures, this did not translate into measurable differences in function or patient-reported quality of life.

“The dosimetric effect seems to be necessary but not sufficient for meaningful patient benefit in OPSCC,” Dr. Thomson explained.

Dr. Thomson emphasized the importance of the study’s rigorous quality assurance across both arms: “We wanted to be confident that both arms delivered the highest-quality care to ensure a valid comparison between these advanced techniques.”