Association of glycaemic control with post-radiation nasopharyngeal necrosis in diabetic patients with nasopharyngeal carcinoma.

BACKGROUND: Post-radiation nasopharyngeal necrosis (PRNN) is a rare but life-threatening late complication in patients with nasopharyngeal carcinoma (NPC). Diabetes mellitus (DM) has been reported as a risk factor for PRNN; however, the impact of long-term glycaemic control on PRNN risk and severity remains unclear. PATIENTS AND METHODS: We conducted a retrospective cohort study of diabetic patients with newly diagnosed NPC treated with intensity-modulated radiotherapy (IMRT) between 2019 and 2022. Long-term glycaemic control was assessed using hemoglobin A1c (HbA1c) levels obtained within 3 months prior to the initiation of radiotherapy and categorized as optimal (<7 %) or suboptimal (≥7 %). Propensity score matching (PSM) was applied to minimize confounding. RESULTS: Among 315 eligible patients, PRNN occurred in 43 (13.7 %) over a median follow-up of 39.7 months. After PSM, 232 patients were included. PRNN developed in 19.0 % of patients with suboptimal glycaemic control compared with 7.8 % of those with optimal control. Suboptimal glycaemic control was significantly associated with an increased risk of PRNN (odds ratio: 2.86, 95 % confidence interval: 1.21-6.76). Higher HbA1c levels were associated with progressively increased PRNN risk (P for trend < 0.0001) and greater necrosis severity. In addition, suboptimal glycaemic control was associated with inferior local recurrence-free, distant metastasis-free, progression-free, and overall survival (all P < 0.05). CONCLUSIONS: Poor glycaemic control is independently associated with increased risk and severity of PRNN and adverse survival outcomes in diabetic patients with NPC. These findings suggest that optimized glycaemic management may represent a clinically actionable strategy to reduce PRNN risk in this vulnerable population.