Impact of Offline Adaptive Radiotherapy on Survival and Quality of Life in Locally Advanced Nasopharyngeal Carcinoma: A Propensity-Matched Retrospective Study

Abstract OBJECTIVE The clinical benefits of offline adaptive radiotherapy(ART) in volumetric modulated arc therapy(VMAT) for locally advanced nasopharyngeal carcinoma (LA-NPC), particularly regarding long-term quality of life, are not well-established due to conflicting evidence.This study aims to clarify the clinical value of offline ART in LA-NPC, particularly its effects on long-term patient survival quality. MATERIALS AND METHODS Retrospectively, 355 patients with LA-NPC treated with VMAT between January 2020 and December 2021 were included to optimize between-group comparability by propensity score matching (PSM) and to systematically assess the difference in efficacy and quality of life between ART and VMAT. The primary study endpoints were overall survival (OS) and progression-free survival (PFS), distant metastasis-free survival (DMFS), and local-regional recurrence-free survival (LRFS), and the survival curves were plotted by the Kaplan-Meier method and compared with between-groups differences by the Log-rank test, and the Cox proportional risk model was used to calculate the corrected risk ratio. At the final follow-up, quality of life was assessed using the Chinese version of the European Organization for Research and Treatment of Cancer (EORTC) core quality of life questionnaire QLQ-C30 (v3.0) and the head and neck cancer-specific module QLQ-H&N35 (v1.0). RESULTS After PSM, a total of 254 patients (127 each in the ART and VMAT groups) were included in the final analysis. Survival analysis showed that no statistically significant differences were observed between the two groups in the 3-year primary survival endpoints: 96.7% vs 95.9% (P = 0.764) for OS, 88.2% vs 86.6% (P = 0.835) for PFS, 92.1% vs 92.8% (P = 0.647) for LRFS, and 91.2% vs 88.9% for DMFS (P = 0.540). The ART group exhibited significantly lower xerostomia incidence (19.1 ± 20.7 vs. 31.6 ± 23.0, P < 0.001) and reduced sticky saliva scores (8.83 ± 16.0 vs. 15.5 ± 18.4, P = 0.004) compared to the non-adaptive VMAT group,Moreover, the ART group demonstrated better cognitive function (86.8 ± 13 vs. 82.7 ± 14.7, P = 0.030) and physical function (96.2 ± 9.84 vs. 93 ± 11.8, P = 0.026). Additionally, multifactorial Cox regression analysis identified EBV and prognostic nutritional index as independent predictors of clinical outcomes. CONCLUSION This long-term follow-up study suggests that offline adaptive radiotherapy can reduce toxicity without affecting the survival of patients with LANPC. Further prospective clinical studies are necessary to validate these findings.