The Host Tissue Repair Vulnerability Index (HTRVI): a composite biomarker for predicting osteoradionecrosis in locally advanced nasopharyngeal carcinoma

Abstract

Osteoradionecrosis of the jaw (ORNJ) remains a major late complication of head and neck radiotherapy, and risk assessment relies mainly on clinical and dosimetric factors. We constructed the Host Tissue Repair Vulnerability Index (HTRVI), a composite biomarker integrating inflammatory, immune-nutritional, and oxygenation-related parameters, to estimate biological susceptibility to ORNJ in locally advanced nasopharyngeal carcinoma (LA-NPC). Methods: This retrospective cohort included 261 LA-NPC patients treated with definitive concurrent chemoradiotherapy between 2010 and 2021. HTRVI was calculated as (CRP × platelet × neutrophil)/(albumin × lymphocyte × hemoglobin). HTRVI was compared with hemoglobin (Hb) and the Global Immune-Nutrition-Inflammation Index (GINI) using receiver operating characteristic analysis. Multivariable logistic regression, restricted cubic spline analysis (RCS), and bootstrap resampling assessed independent association, continuous risk relationship, and internal validation. Results: During a median follow-up of 63.8 months, 24 patients (9.2%) developed ORNJ. HTRVI showed superior discrimination (AUC, 0.864; 95% CI, 0.769–0.932) compared with Hb (AUC, 0.785; p = 0.001) and GINI (AUC, 0.759; p = 0.045). HTRVI remained independently associated with ORNJ after adjustment for mandibular mean dose and post-CCRT tooth extraction burden (OR per standard deviation increase, 4.81; 95% CI, 1.10–20.99; p = 0.037). RCS analysis showed a significant continuous association between HTRVI and ORNJ risk (Poverall < 0.001) without nonlinearity (Pnonlinear = 0.736). Internal validation showed minimal optimism (bootstrap-corrected AUC, 0.993). Conclusions: HTRVI was independently associated with ORNJ and provided additional predictive information beyond established clinical and dosimetric factors in this single-center cohort. The continuous HTRVI–ORNJ association supports a biological continuum model of host tissue repair vulnerability. However, HTRVI should currently be regarded as an investigational biomarker requiring independent external and prospective validation before clinical implementation.