Published in JAMA, the paper by the UPenn group accessed PBT side effects in the concurrent chemoradiotherapy for locally advanced cancer setting. 1483 adult patients with nonmetastatic, locally advanced cancer treated with concurrent chemoradiotherapy with curative intent were matched with 391 PBT and 1092 photon-based therapy.

The result shown that proton chemoradiotherapy was associated with a significantly lower relative risk of 90-day adverse events of at least grade 3 (0.31; 95% CI, 0.15-0.66, P = .002), 90-day adverse events of at least grade 2 (0.78; 95% CI, 0.65-0.93, P = .006), and decline in performance status during treatment (0.51; 95% CI, 0.37-0.71; P < .001). There was no difference in disease-free or overall survival.