Intensity-modulated proton therapy vs intensity-modulated radiotherapy in nasopharyngeal carcinoma: a case–control study

Abstract

SummaryBackgroundIntensity-modulated proton therapy (IMPT) is associated with fewer acute toxicities compared with intensity-modulated radiotherapy (IMRT) in definitive treatment of nonmetastatic nasopharyngeal carcinoma (NPC). Longer term efficacy and safety data are warranted to appraise the comparative benefit of IMPT for this population. The aim of this study was to evaluate the long-term toxicity and survival outcomes of NPC treated with IMPT vs IMRT at a tertiary academic cancer center during 2016–2022.MethodsSixty-seven (42.1%) cases treated by IMPT, and 92 (57.9%) controls treated by IMRT were included.FindingsThe median follow-up time was 55.4 months (interquartile range [IQR], 32.1–73.8 months). The incidence of any grade 2+ acute toxicity was lower with IMPT than IMRT (86.6% vs 97.8%, p = 0.009). Based on the logistic regression analysis, radiotherapy modality (IMRT vs IMPT) was significantly associated with developing any grade 2+ acute toxicity (odds ratio, 0.177; 95% confidence interval 0.035–0.886; p = 0.035). The incidence of grade 2+ late toxicity was not significantly different (p > 0.05) following IMPT (40.3%) and IMRT (52.7%). There were no statistically significant differences following IMRT and IMPT in 5-year cumulative incidence of local or regional failures [16.4% (9.1–25.6) vs 14.1% (6.5–24.7)], progression free survival and overall survival.InterpretationAlthough there were no statistically significant differences in incidence of late toxicities or oncologic outcomes, IMPT was associated with lower incidence of acute toxicity in comparison with IMRT.FundingThis research was funded in part through the National Institutes of Health/National Cancer Institute Cancer Center Support Grant P30 CA008748.