ESTRO 2022 - Abstract Book

S64

Abstract book

ESTRO 2022

Results In total 186 pts were included, of which 77% were males. The median age for the whole cohort was 62 years (range 40-85). The majority (143, 89%) had p16-pos OPC with 155 (83%) receiving concurrent chemotherapy and 139 (75%) bilateral neck irradiation. Baseline characteristics for both groups are shown in Table 1. Proton therapy was associated with significantly less weight loss at the end of RT (p=0.01, mean weight loss 2.6 kg vs 4.5kg). Equal proportions of proton (34%) and photon pts (37%) required hospitalization during and up to 60 days day after treatment completion (p=0.7), mean days spent in hospital were 4 days and 3.5 days respectively (p=0.7). No difference between groups was observed for opioids use in the observation period. At 8-weeks post-treatment follow-up 5 pts in protons and 7 pts in photons still had persisting grade 3 mucositis (p=0.6). There were statistically significant differences in skin reactions between groups, with more grade 3 toxicity in protons at the end of RT (26% vs 14%, p=0.04). However, at 8 weeks post-RT no grade 3 skin reactions were registered in protons. At 8-weeks post-RT feeding tube was used for 6 (10%) of proton-treated pts and 8 (7%) for photon (p= 0.5).