Proton Therapy vs Traditional Radiation Therapy in Patients With Oropharyngeal Cancer

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Intensity-modulated proton therapy may achieve similar clinical outcomes and offer significant benefits compared with traditional intensity-modulated radiation therapy in patients with oropharyngeal cancer, according to preliminary data from a multi-institutional phase III trial presented by Frank et al at the 2024 ASCO Annual Meeting (Abstract 6006).


Proton therapy has both biological and physical advantages over traditional radiation therapy that uses photons. Unlike photons, protons have mass and can be stopped by the human body—allowing proton radiation to be delivered only to targeted areas and limiting the amount that reaches nearby healthy tissues.

Study Methods and Results

Researchers randomly assigned 440 patients with oropharyngeal cancer to receive either intensity-modulated proton therapy (n = 221) or intensity-modulated radiation therapy (n = 219) as part of chemoradiation. Patients were stratified based on human papillomavirus status, smoking status, and whether they had received induction chemotherapy.

“Historically, [these kinds] of large-scale trials to confirm the benefits of proton therapy have been challenging, due in part to relatively few patients having access to proton therapy centers,” explained lead study author Steven Frank, MD, Professor of Radiation Oncology and Executive Director of the Particle Therapy Institute at The University of Texas MD Anderson Cancer Center.

After a median follow-up of 3 years, patients who received intensity-modulated proton therapy had a progression-free survival rate of 83.0% vs 83.5% among those who received intensity-modulated radiation therapy. Intensity-modulated proton therapy was statistically noninferior to intensity-modulated radiation therapy. However, the researchers observed a significant reduction of malnutrition in the intensity-modulated proton therapy group, in which 24% of patients sustained their nutrition with less than 5% weight loss during treatment vs 14% of those in the intensity-modulated radiation therapy group. Further, there was a notable reduction in feeding-tube dependence in the intensity-modulated proton therapy group compared with the intensity-modulated radiation therapy group (28% vs 42%, respectively).


“The results of this multicenter phase III randomized trial provide evidence for [intensity-modulated proton therapy] as a new standard-of-care treatment approach for the management of head and neck tumors. This is significant for patients as it represents a curative, de-intensified option compared to traditional radiation therapy,” underscored Dr. Frank. “Encouraging results like these demonstrate the benefits of proton therapy and hopefully help pave the way for increased access for patients in need,” he concluded.

Disclosure: The research in this study was supported by the National Institutes of Health, National Cancer Institute, and Hitachi; and in part by Ion Beam Applications. For full disclosures of the study authors, visit

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