Ling Xiao, Yu-Di Liu, ZHANG Xue, Shi-Chuan Zhang, Jia-Hua Lyu
BACKGROUND Radiotherapy-induced toxicity and low muscle mass (LMM) significantly compromise treatment efficacy and survival in patients with esophageal squamous cell carcinoma (ESCC). Although body mass index (BMI) is a simple nutritional screening tool, its utility in predicting LMM in patients with ESCC remains unclear. AIM To investigate the association between baseline BMI and LMM prevalence and to evaluate the impact of LMM on survival outcomes in ESCC patients undergoing chemoradiotherapy. METHODS In this retrospective cohort study, 360 consecutive patients with ESCC treated with chemoradiotherapy at Sichuan Cancer Hospital from 2012 to 2023 were enrolled. LMM was assessed using skeletal muscle index derived from L3-level computed tomography images based on validated sex-specific cutoff values. Multivariable logistic regression was performed to analyze the association between BMI and LMM. A Cox proportional hazards model was used to assess the association between LMM and overall survival (OS) after adjusting for key confounders, including age, sex, clinical stage, and treatment regimen. RESULTS The prevalence of LMM was 23.0% in the patient cohort. Multivariable analysis showed that each 1-unit increase in BMI was associated with a 38.7% reduction in the odds of LMM (odds ratio: 0.613; 95% confidence interval: 0.531-0.707; P < 0.001). Patients with LMM had significantly shorter median OS than those without LMM (17.0 months vs 28.7 months; P < 0.001). The subgroup with combined low BMI and LMM had the poorest prognosis (median OS: 17.0 months). Baseline BMI was an independent predictor of LMM in patients with ESCC undergoing chemoradiotherapy and was significantly correlated with survival. CONCLUSION A combined evaluation of BMI and LMM enables the early identification of high-risk individuals, underscoring the importance of routine pretreatment assessment and timely nutritional and functional interventions to improve clinical outcomes.