Assessing Insulin Resistance: The Triglyceride-Glucose Index as a Predictor of Survival in Nasopharyngeal Carcinoma

Xin Hua¹Fei Xu²Xu-Xin Lin^1,3Lin Yongmiao⁴Zhiqing Long⁴Si-Fen Wang⁴Fangfang Duan⁴Chao Zhang⁴Xin Huang⁴Wen Xia⁴Wen-Chao Li⁵Ao-Qiang Chen^4*De-Huan Xie^1*Shasha Du^1*

• ¹Department of Radiation Oncology, Guangdong Provincial People's Hospital, Guangzhou, China
• ²Department of Radiation Oncology, Shanghai Jiao Tong University Medical School Affiliated Ruijin Hospital, Shanghai, China
• ³South China University of Technology School of Medicine, Guangzhou, China
• ⁴State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, China
• ⁵Department of oncology, The Sixth Affiliated Hospital of South China University of Technology, Foshan, China

Background: The triglyceride-glucose (TyG) index, a simple marker of insulin resistance, has shown prognostic value in various malignancies. However, its predictive utility for survival in nasopharyngeal carcinoma (NPC) patients remains largely unexamined. This study aimed to assess the prognostic value of the TyG index and to develop novel predictive models for survival outcomes in NPC. Methods: We retrospectively analyzed 833 NPC patients treated with concurrent chemoradiotherapy (CCRT). All patients were staged according to the 8th edition of the American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) TNM staging system. The TyG index was calculated as ln (fasting triglycerides × fasting glucose). Primary and secondary endpoints were overall survival (OS), locoregional recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS), respectively. We utilized univariate and multivariate Cox proportional hazards models to identify independent prognostic factors and subsequently constructed and validated nomograms. Results: A low TyG index was significantly associated with better survival outcomes, serving as an independent predictor for OS (hazard ratio [HR]= 0.534; P=0.007), LRFS (HR=0.423; P<0.001), and DMFS (HR=0.575; P=0.010) in multivariate analysis. The newly developed nomograms demonstrated favorable discriminative performance, significantly outperforming the conventional TNM staging system (concordance index [C-index] for OS: 0.722 vs. 0.634). Conclusions: The TyG index is a readily available, powerful prognostic biomarker for NPC patients. Incorporating the TyG index into prognostic nomograms offers a superior tool for individualized risk stratification and treatment planning, representing a valuable advancement over traditional staging systems.