Intensity-modulated proton therapy (IMPT) achieved similar clinical outcomes and offered significant benefits, according to preliminary data from a multi-institution Phase III trial led by researchers at The University of Texas MD Anderson Cancer Center. for patients compared to traditional intensity-modulated radiation therapy (IMRT) as part of chemoradiation treatment for patients with oropharyngeal (head and neck) cancer.
The results were presented today at the 2024 Annual Meeting of the American Society of Clinical Oncology (ASCO) by Dr. Steven Frank, professor of Radiation Oncology and executive director of the Particle Therapy Institute at the University of MD Anderson Cancer Center. Texas.
With a median follow-up of three years, the progression-free survival (PFS) rate was 83% and 83.5% for IMPT and IMRT, respectively, and IMPT was statistically noninferior to IMRT. There was a significant reduction in malnutrition with IMPT, with 24% of patients maintaining their nutrition with less than 5% weight loss during treatment compared to 14% of those receiving IMRT. Additionally, there was a significant reduction in feeding tube dependency with IMPT of 28%, compared to 42% with IMRT.
“The results of this phase III multicenter randomized trial provide evidence for IMPT as a new standard of care approach for the treatment of head and neck tumors,” Frank said. “This is important for patients as it represents a curative and de-intensified option compared to traditional radiotherapy.”
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. This allows proton radiation to be delivered specifically to the target area, limiting the amount that reaches nearby normal tissues. This trial represents the largest randomized phase III trial to date to investigate proton therapy compared to traditional radiation.
The trial enrolled 440 patients at 21 sites in the US, 219 received IMRT and 221 received IMPT. Patients were stratified by human papillomavirus (HPV) status, smoking, and whether they had received induction chemotherapy. The primary endpoint of the study was the three-year PFS rate.
“Historically, these types 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,” Frank said. “Encouraging results like these demonstrate the benefits of proton therapy and hopefully help pave the way for greater access for patients in need.”
This study was supported by grants from the National Institutes of Health (NIH)/National Cancer Institute (NCI) (U19CA021239, R03CA188162, R56DE025248) and Hitachi. Frank reports on proton-related grant funding from Hitachi and fees from Ion Beam Applications SA (IBA). He also has non-proton healthcare relationships with Boston Scientific (consulting fees), Affirmed Pharma (NIH grant), and C4 Imaging (founder, scientific advisory board, patents/royalties, ownership interest).