Early Change in Subcutaneous Fat Attenuation on Follow-up CT Provides Prognostic Information Beyond AFP in Advanced Hepatocellular Carcinoma During Immunotherapy.

RATIONALE AND OBJECTIVES: To determine whether early CT-derived body composition changes provide prognostic information beyond AFP dynamics in patients with advanced hepatocellular carcinoma (HCC) receiving immunotherapy. MATERIALS AND METHODS: This retrospective study included patients with advanced HCC who underwent baseline and early follow-up contrast-enhanced CT. Body composition was assessed on portal venous phase CT images at the L3 level. A clinical trial cohort was used for model development, and an independent real-world cohort was used for validation. Exploratory analyses evaluated longitudinal changes in CT-derived body composition, after which prognostic models were sequentially constructed using baseline clinical factors, AFP change, and subcutaneous adipose tissue (SAT) attenuation change. Progression-free survival (PFS) and overall survival (OS) were evaluated. RESULTS: Among 205 patients with paired baseline and first on-treatment CT examinations, 200 with paired AFP measurements were included in model comparisons. AFP change improved prognostic assessment for both PFS and OS in the clinical trial and real-world cohorts. SAT attenuation change added little for PFS but provided additional prognostic information for OS in both cohorts. Adding SAT attenuation change increased the C-index for OS from 0.705 to 0.720 in the clinical trial cohort (P < 0.001) and from 0.706 to 0.726 in the real-world cohort (P = 0.031). Overall, AFP appeared to reflect early tumor-related change, whereas SAT attenuation change provided complementary information more closely related to survival. CONCLUSION: Early SAT attenuation change on follow-up CT was associated mainly with OS and provided modest incremental prognostic information beyond AFP dynamics.