Effect of body mass index and age on the prognosis of non-metastatic nasopharyngeal carcinoma

PURPOSE: Given the critical roles of body mass index (BMI) and age in cancer prognosis, this study investigated their impact on non-metastatic nasopharyngeal carcinoma (NPC). METHODS: Patients aged > 18 years with newly diagnosed non-metastatic NPC treated at the First Affiliated Hospital of Guangxi Medical University between June 2016 and March 2020 were retrospectively enrolled. BMI at diagnosis was classified into underweight, normal, overweight, and obese categories according to the WHO Asian BMI criteria, and patients were stratified into 20-year age intervals. RESULTS: A total of 674 patients were included in the study. There were 310 (46.0%), 244 (36.2%), 45 (6.7%), and 75 (11.1%) patients in the normal, overweight, obese, and underweight BMI groups, respectively. Age distribution was 205 (30.4%) young, 393 (58.3%) middle-aged, and 76 (11.3%) older. The median follow-up duration was 72 months (range, 3-98 months). The 5-year overall survival (OS) and event-free survival (EFS) rates were 79.2% and 77.0%, respectively. Overweight patients had significantly better OS than those with normal BMI (85.2% vs. 77.4%, p = 0.021) or underweight BMI (85.2% vs. 69.3%, p < 0.001). Underweight patients had a worse EFS than overweight (66.7% vs. 81.6%, p = 0.002) or normal patients (66.7% vs. 76.8%, p = 0.029). Survival outcomes declined with age (p < 0.05). Cox multivariate analysis identified underweight BMI and advanced age as independent adverse prognostic factors (p < 0.05). CONCLUSION: Underweight BMI and advanced age at diagnosis are associated with poor prognosis in non-metastatic NPC. These findings confirm previous observations in a modern IMRT-treated cohort and emphasize that these associations are hypothesis-generating, without implying direct causal effects.