Association of TyG-BMI and malnutrition with reduced survival outcomes in patients with cancer: a prospective study.

BACKGROUND: Several triglyceride-glucose (TyG)-related indices are used to assess insulin resistance (IR), but the better indicator for patients with cancer remains undetermined. The prognostic value of TyG-body mass index (TyG-BMI), its association with malnutrition, and underlying mediating mechanisms in large Chinese multicenter cohorts need further clarification. METHODS: This prospective, multicenter study enrolled 5,221 patients with cancer from the INSCOC cohort. We compared the prognostic performance of TyG-BMI with other TyG-related IR indices. Logistic regression was used to explore the relationship between TyG-BMI and malnutrition (PGSGA). Cox regression and mediation analyses were performed to evaluate prognostic value and mediating pathways. RESULTS: TyG-BMI was identified as a useful indicator TyG-related IR index, with the highest time-dependent AUC values and C-index. High TyG-BMI was independently associated with better overall survival (adjusted HR = 0.83, 95%CI: 0.76-0.91, p < 0.001) and lower malnutrition risk (adjusted OR = 0.42, 95%CI: 0.37-0.48, p < 0.001). The prognostic benefit was most significant in esophageal and colorectal cancer. Exploratory pathway decomposition analyses showed that PGSGA (48.2%), CRP (13.6%), KPS (18.5%), and ECOG PS (18.9%) accounted for partial components of the correlation between TyG-BMI and overall survival. Low TyG-BMI combined with malnutrition reduced 1-year survival in patients with cancer (1-year survival rate = 70.7%; median survival time = 27.2 months). CONCLUSION: TyG-BMI, a simple composite index based on routine clinical indicators, is a TyG-related insulin resistance index for Chinese patients with cancer. High TyG-BMI is significantly associated with a lower risk of malnutrition and better overall survival. Exploratory pathway analyses indicated nutritional status, systemic inflammation and physical function partially contributed to the crude correlation between TyG-BMI and survival. TyG-BMI and malnutrition are jointly associated with reduced survival outcomes in patients with cancer, supporting its clinical value for prognostic stratification and nutritional-metabolic management.