BOA-Derived Volumetric CT Body Composition Provides Prognostic Information Beyond BMI in Surgically Treated Head and Neck Squamous Cell Carcinoma: A Retrospective Cohort Study

Background/Objectives: To evaluate whether automated three-dimensional volumetric body composition metrics from the Body and Organ Analysis (BOA) algorithm provide prognostic information beyond body mass index (BMI) for overall survival (OS) in surgically treated head and neck squamous cell carcinoma (HNSCC), and to compare cervical (C1–C7) measurements with thoracic and abdominal regional comparators. Methods: This single-center retrospective cohort study included 391 surgically treated HNSCC patients (2010–2019). Pretreatment CT scans were processed using the open-source BOA algorithm to obtain volumetric muscle, bone, and adipose measurements across cervical (C1–C7), thoracic, and abdominal regions. Composite indices—Sarcopenia Index (SI = Muscle/Bone) and Myosteatotic Fat Index (MFI = IMAT/TAT)—were derived; Cerv SI denotes the volumetric C1–C7 ratio. The predefined primary Cox model adjusted for age, sex, tumor site, UICC stage, treatment, HN-CCI, and secondary malignancy. Results: Of 391 patients (91% male, median follow-up 5.0 years, 141 deaths), BMI was not independently associated with OS (HR 0.88, p = 0.15). Cerv SI was associated with OS in the minimally adjusted model (HR 0.71, 95% CI 0.58–0.88, p = 0.002) and remained independent in the primary clinically adjusted model (HR 0.72, 95% CI 0.58–0.90, p = 0.004; C-index 0.67). When BMI and Cerv SI were entered together, Cerv SI remained independently associated (HR 0.72, p = 0.006) while BMI was null (HR 1.01, p = 0.95). Conclusions: BOA-derived cervical volumetric body composition is associated with overall survival beyond BMI and is obtainable from routine head and neck CT. Prospective validation and comparison with established two-dimensional C3/L3 methods are warranted before clinical use.