Evaluation of Body Mass Index and Survival of Nasopharyngeal Carcinoma by Propensity-Matched Analysis: An Observational Case-Control Study

The effect of pretreatment body mass index on survival of nasopharyngeal carcinoma remains contradictory. All patients (N = 1778) underwent intensity-modulated radiotherapy with or without chemotherapy. Body mass index was categorized as underweight (<18.5 kg/m(2)), normal weight (18.5–22.9 kg/m(2)), overweight (22.9–27.5 kg/m(2)), and obesity (≥27.5 kg/m(2)). Propensity score matching method was used to identify patients with balanced characteristics and treatment regimen. Disease-specific survival (DSS), overall survival (OS), distant metastasis–free survival (DMFS), and locoregional relapse–free survival were estimated by Kaplan–Meier method and Cox regression. Following propensity matching, 115 (underweight vs normal), 399 (overweight vs normal), and 93 (obese vs normal) pairs of patients were selected, respectively. In univariate analysis, underweight patients had inferior DSS/OS (P = 0.042) and DMFS (P = 0.025) while both overweight and obese patients showed similar survival across all the endpoints (P ≥ 0.098) to those with normal weight. In multivariate analysis, underweight remained predictive of poor DSS/OS (P = 0.044) and DMFS (P = 0.040), whereas overweight (P ≥ 0.124) or obesity (P ≥ 0.179) was not associated with any type of survival. Underweight increased the risk of death and distant metastasis, whereas overweight or obese did not affect the survival of nasopharyngeal carcinoma. This provides support for early nutritional intervention during the long waiting time before treatment.