Proton Beam Therapy for Oropharyngeal Cancer (TORPEdO): a Phase 3, Randomised Controlled Trial
David J Thomsonet al.
The article investigates whether proton beam therapy (PBT) can reduce treatment-related toxicity compared with conventional photon intensity-modulated radiotherapy (IMRT) in patients with oropharyngeal cancer. Because survival rates for HPV-associated oropharyngeal cancers are generally high, reducing long-term side effects and preserving quality of life have become major priorities in radiotherapy research.
The trial enrolled patients with locally advanced oropharyngeal carcinoma who were randomly assigned to receive either proton beam therapy or standard photon IMRT combined with chemotherapy. The study evaluated both oncological outcomes and treatment-related toxicities, particularly side effects affecting swallowing, nutrition, and oral function. Researchers also assessed patient-reported quality of life during and after treatment.
During the development of the trial, proton therapy demonstrated important dosimetric advantages. Owing to the Bragg peak effect, proton beams delivered lower radiation doses to surrounding healthy tissues such as the salivary glands, oral cavity, pharyngeal muscles, and esophagus. These reductions translated into clinically relevant benefits. Patients treated with proton therapy experienced lower rates of severe acute toxicities, including mucositis, dysphagia, xerostomia, and feeding-tube dependence. In addition, quality-of-life scores recovered more rapidly in the proton therapy group. Despite these differences in toxicity, tumor control outcomes, progression-free survival, and overall survival remained comparable between the two treatment approaches.
In conclusion, the TORPEdO trial supports proton beam therapy as an effective alternative to photon IMRT for oropharyngeal cancer. While both modalities achieved similar cancer control, proton therapy significantly reduced treatment-related toxicity and improved functional recovery. The study suggests that proton therapy may be especially beneficial for younger patients with long expected survival, although the authors note that cost-effectiveness and wider accessibility remain important considerations for future implementation.
Published by Lancet 2026; 407: 1259–75
