“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.”
Differences Between Traditional Radiation Therapy and Proton Therapy
Traditional radiation therapy, or intensity-modulated radiation therapy (IMRT), uses photons which pass through the body without stopping. This leaves both an entry and exit dose of radiation in non-targeted areas and can result in collateral damage to normal tissues. Proton therapy, also known as intensity-modulated proton therapy (IMPT), has unique physical and biological properties which reduce radiation exposure and collateral damage to normal tissues.
Overview of the Largest Randomized Phase III Trial
This is the largest randomized Phase III trial to date comparing proton therapy to traditional radiation therapy. The study randomized 440 patients at 21 sites across the U.S. into the two arms of the trial, and stratified based on HPV status, smoking status, and whether patients had received induction chemotherapy.
Three- and Five-Year Progression-Free Survival Outcomes
The primary endpoint of the non-inferiority study was the three-year progression-free survival (PFS) rate. The three-year PFS rate was 82.5% with the proton arm and 83% with the traditional arm, a difference that was not statistically different. Five-year PFS rates were 81.3% with proton therapy and 76.2% with radiation therapy.
Source: University of Texas MD Anderson Cancer Center