Abstract 5961: MRI-based sternocleidomastoid muscle assessment as a predictive marker for sarcopenia and survival outcomes in nasopharyngeal carcinoma patients undergoing concurrent chemoradiotherapy

Abstract Purpose/Objective(s): Sarcopenia is strongly linked to poor survival outcomes and increased treatment-related toxicity in solid tumors. Both pre- and post-treatment muscle loss negatively impact prognosis, emphasizing the importance of muscle mass evaluation. This study investigates the sternocleidomastoid (SCM) muscle, an accessible target in head and neck examinations, as a predictive marker for survival outcomes in nasopharyngeal carcinoma (NPC). Using MRI-based assessment, this study aims to establish SCM’s utility in prognosis prediction and improve patient management. Materials/Methods: This multi-institutional study analyzed 976 NPC patients treated at three hospitals between 2002 and 2019. Among them, 504 newly diagnosed patients underwent concurrent chemoradiotherapy, and complete pre- and post-treatment MRI data were available for 286. SCM muscle analysis was conducted using post-contrast T1-weighted MRI at the third cervical vertebra (C3). Measurements included cross-sectional area (SCMA), long axis (SCML), and short axis (SCMS). Derived parameters included SCMAD (SCML + SCMS), SCMAA (SCML × SCMS), and SCMR (SCMS/SCML). Ratios of post/pre-treatment values were calculated to reflect muscle loss. Optimal cutoff points for sarcopenia-related parameters were determined, and predictors of overall survival (OS) were evaluated using Cox proportional hazards regression and Kaplan-Meier survival analysis to visualize OS differences among groups stratified by sarcopenia status. Results: Among the 286 patients analyzed, 63% were male, and 51.2% were diagnosed between 40 and 60 years old. Advanced stages were common: 25.8% stage III and 40.7% stage IV. Over a median 4.7-year follow-up, 93 patients (31.8%) died. OS rates were 93.2% at one year and 68.9% at five years. Post/pre-treatment SCM parameters (SCMA, SCMS, SCMR) showed no statistically significant results. However, certain parameters approached significance: SCML (cutoff 0.75, p = 0.1147), SCMAD (cutoff 0.47, p = 0.338), and SCMAA (cutoff 0.26, p = 0.328), suggesting trends warranting further investigation. Conclusion: BMI alone may inadequately reflect muscle loss, whereas SCM parameters measured via MRI offer a reliable method to assess sarcopenia and predict survival. Our findings indicate that SCM provides effective metrics for prognosis in NPC, but further studies with larger samples are needed to identify the most impactful predictive parameter and optimize its clinical utility. Citation Format: Jeng-You Wu, Emily Chia-Yu Su. MRI-based sternocleidomastoid muscle assessment as a predictive marker for sarcopenia and survival outcomes in nasopharyngeal carcinoma patients undergoing concurrent chemoradiotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5961.