A recent study published in The Lancet has found that proton therapy, also known as intensity-modulated proton therapy (IMPT), provides a significant survival benefit for patients with oropharyngeal cancers when compared to traditional radiation therapy, or intensity-modulated radiation therapy (IMRT). The research was led by a team from The University of Texas MD Anderson Cancer Center and is the first randomized Phase III trial to show a survival advantage for proton therapy in this patient group.
"This is important, level one evidence that proton therapy has both a survival benefit and quality-of-life improvement for these patients and should be the standard of care for advanced cases of oropharyngeal cancer," said Steven Frank, M.D., executive director of technology and innovation and deputy division head of strategic programs for Radiation Oncology. "These results demonstrate the advantages of proton therapy for head and neck cancer patients, and this study could lay the foundation for increased accessibility for patients who may benefit."
Oropharyngeal cancers are often treated with proton therapy due to their location near sensitive organs and tissues. The trial included 440 patients with stage III or IV disease at 21 sites across the United States. Participants were randomly assigned to receive either IMPT or IMRT.
After five years, overall survival among those treated with proton therapy was 90.9%, compared to 81% among those who received traditional radiation—a statistically significant difference. In addition to improved survival rates, patients receiving proton therapy experienced fewer side effects such as difficulty swallowing (34% versus 49%), feeding tube dependence (26.8% versus 40.2%), dry mouth (33% versus 45%), and severe lymphopenia (76% versus 89%) compared to those treated with IMRT.
"The primary thing for patients to understand is these trials overwhelmingly show that both proton therapy and traditional radiation are great treatment options," Frank said. "That said, these results indicate a survival benefit for proton therapy in oropharyngeal cancer patients as well as reduced high grade toxicities during treatment and less feeding tube dependence. These results, along with other recent data, highlight the importance of continuing to identify which patients are most likely to benefit from proton therapy both in the short term and the long term."
Traditional radiation uses photons that pass through the body, exposing non-targeted tissues to radiation both entering and exiting the body. In contrast, proton therapy’s unique properties limit exposure only to targeted areas, reducing potential harm to healthy tissues.
The main goal of this non-inferiority study was three-year progression-free survival (PFS). Results showed no significant difference at three years: PFS rates were 82.5% in the IMPT arm versus 83% in the IMRT arm. However, at five years, PFS was higher in the group treated with protons (81.3%) than in those given traditional radiation (76.2%).
