Patient-reported outcomes between proton and photon therapy in nasopharyngeal carcinoma patients: A longitudinal cohort study.

Background and purpose: This study aimed to compare patient-reported outcomes (PROs) between intensity-modulated proton therapy (IMPT) and volumetric-modulated arc therapy (VMAT) in treating nasopharyngeal carcinoma (NPC). Materials and methods: A prospective cohort study was conducted at a tertiary care center from 2021 to 2023. Newly diagnosed NPC patients were assessed using the modified 28-item symptom distress scale at seven time points, from baseline (T0) to one year post-radiotherapy (RT) (T6). The analysis focused on symptom changes during the acute phase (T0 to T3 [one month post-RT]) using linear mixed models. Sensitivity analyses incorporated inverse probability treatment weighting and data from non-metastatic patients adhering to survey protocols. Results: IMPT recipients (n = 65) had higher education levels, marital stability, household incomes, and better performance statuses compared to VMAT recipients (n = 36). Oral-related symptoms peaked by the seventh week of RT and declined thereafter. IMPT significantly reduced "oral ulcer" (coefficient: -0.83, SE: 0.27) and "difficulty opening mouth" (coefficient: -0.44, SE: 0.18) symptoms by the seventh week but did not improve "dry mouth." "Tinnitus" was rated as more distressing than "hearing difficulty," with no significant differences between IMPT and VMAT for ear-related symptoms. Sensitivity analyses validated these findings. Conclusion: IMPT was associated with reduced severity of specific oral-related symptoms during the acute phase of RT compared to VMAT. While these findings suggest potential benefits of IMPT, baseline differences between groups necessitate cautious interpretation and further validation through randomized studies.