Concurrent chemoradiotherapy is the routine treatment for several cancers; however, it is associated with a high risk of morbidity. When combined with a proton or photon therapy, concurrent chemoradiotherapy may achieve outcomes with reduced toxicity. This study aims to compare the effectiveness of proton and photon therapy with concurrent chemoradiotherapy in reducing 90-day unplanned hospitalizations and other adverse events.

This nonrandomized, retrospective, comparative effectiveness study included a total of 1,483 patients with nonmetastatic, locally advanced cancer treated with concurrent chemoradiotherapy. Of 1,483 patients, 391 received proton therapy, and 1,092 received photon therapy. The primary outcomes of the study were 90-day adverse events associated with unplanned hospitalizations. ECOG performance status decline and 90-day adverse treatment outcomes were also considered.

Of 1,483 patients, those who were receiving proton therapy were significantly older and had lower integral radiation dose to outside-target tissues. ECOG performance status and baseline grade≥2 toxicity was similar between the two groups. Propensity score weighted analysis suggested that proton chemotherapy was associated with a lower relative risk of 90-day treatment adverse events (0.31), as compared with photon therapy (0.78). 

The research concluded that proton therapy with concurrent chemoradiotherapy was safer and caused fewer unplanned hospitalizations than photon therapy.