Purpose <p>To investigate and compare the prognostic value of tumor volumetric characteristics during induction chemotherapy (IC) for advanced nasopharyngeal carcinoma (NPC).</p> Materials and methods <p>A retrospective cohort of 250 patients with NPC treated with IC followed by radiotherapy or chemoradiotherapy was analyzed. Tumor volumes were measured using MRI at two time points of before-treatment and after-IC. Cohorts with high and low tumor heterogeneity were identified by analyzing the gross tumor volume (GTV) through the gray-level co-occurrence matrix (GLCM). Incorporating the clinical factors, volumetric characteristics (V_pre−IC, V_post−IC, ΔV_abs, and ΔV_rel) were evaluated to identify the prognostic value using univariable and multivariable analyses in various cohorts, respectively. Kaplan-Meier survival analyses with median and optimal cutoff values were conducted. Multivariable analysis was repeated on 1 × 10⁵ resampled cohorts with the Bootstrap method to identify the feature importance. Subgroup analyses were performed based on T-category, IC regimens, post-IC treatment protocols, and tumor changes.</p> Results <p>There is virtually no correlation between V_post−IC and ΔV_rel with ρ = -0.08. Various analyses all suggest V_post−IC emerged as the most robust biomarker across all endpoints (<i>P</i> &lt; 0.001 ∼ 0.002), followed by ΔV_rel and T-category, which were more important than the other features. The predictive value of V_post−IC surpasses that of ΔV_rel especially in the high heterogeneity cohort. Specifically, a V_post−IC value of 20.6&#xa0;cm³ could be regarded as a threshold provided optimal risk stratification for progression-free survival (PFS) and overall survival (OS).</p> Conclusion <p>V_post−IC is a critical biomarker for determining clinical outcomes in advanced NPC. Patients with V_post−IC measurements above 20.6&#xa0;cm³ are classified as high-risk, indicating a requirement for escalating radiotherapy and/or chemotherapy.</p>