Phase angle as a prognostic nutritional marker for survival in nasopharyngeal carcinoma patients undergoing chemoradiotherapy: a prospective cohort study

Background Conventional nutritional indicators have limitations in predicting outcomes for nasopharyngeal carcinoma (NPC) patients undergoing chemoradiotherapy. Phase angle (PA), a bioelectrical impedance-derived measure of cellular integrity, has emerged as a prognostic marker in various malignancies but remains understudied in NPC. This study investigated whether PA provides superior prognostic information for overall survival (OS) compared to conventional indicators. Methods In this prospective cohort study, 380 newly diagnosed NPC patients scheduled for chemoradiotherapy were enrolled. PA was measured using InBody S10. Nutritional status was assessed via body mass index (BMI), serum albumin, and the Patient-Generated Subjective Global Assessment (PG-SGA). OS was the primary endpoint. For Kaplan–Meier visualization, patients were stratified by the median PA value. Multivariable Cox regression and time-dependent ROC analyses were performed. Results Over a median 60-month follow-up, 27 deaths (7.1%) occurred. PA showed significant correlations with BMI (r = 0.512, p < 0.001), albumin (r = 0.685, p < 0.001), and PG-SGA (r = −0.738, p < 0.001). After adjustment for age and TNM stage, PA independently predicted OS (HR = 0.638 per 1°increase, 95% CI: 0.483–0.853, p = 0.002). PA demonstrated promising predictive accuracy (AUC = 0.742, 95% CI: 0.655–0.829). Given the moderate event number, formal AUC comparisons were not performed. Conclusion PA may be an independent prognostic factor for newly diagnosed NPC patients undergoing chemoradiotherapy. These findings may support its potential utility in baseline risk assessment, though validation in larger cohorts is warranted.