Fat-free Muscle Index Predicts Overall Survival in Mass-forming Intrahepatic Cholangiocarcinoma Patients: A Sex-stratified Analysis

Abstract

IntroductionSarcopenia is associated with adverse outcomes in patients with malignancies, it remains unclear whether the sex discrepancy of sarcopenia or muscle loss leads to different prognoses in patients with mass-forming intrahepatic cholangiocarcinoma (MICC).Material and methodsPatients who were pathologically diagnosed with MICC and underwent partial hepatectomy between 2012 and 2019 were recruited. Fat-free muscle areas (FFMA) were defined as areas of bilateral erector spinae muscles on dual-echo T1-weighted gradient-recalled-echo images at the level of radix of the superior mesenteric artery. FFMI (fat-free skeletal muscle index) was calculated by dividing FFMA by individual’s height squared. The prognostic value of FFMI was investigated using Kaplan-Meier method and multivariable Cox regressions in both the entire cohort and sex-specific subgroups.ResultsA total of 157 patients were finally included. Cutoff values for the definition of low FFMI were 14.19 cm2/m2 in males and 11.07 cm2/m2 in females. Patients with low FFMI had significantly shorter overall survival (OS) than those with high FFMI in the entire cohort (19.42 vs 35.29 months, p=0.0067) and male patients (17.25 vs 37.19 months, p=0.006), but not females. Multivariate analyses showed that low FFMI was a significant predictor of OS in the entire cohort (HR 1.725, 95%CI 1.054-2.821, p=0.03) and male patients (HR 2.145, 95%CI 1.113-4.133, p=0.023). No association between FFMI and disease-free survival was found in both the entire cohort and sex-specific subgroups.ConclusionsPreoperative FFMI measured by MRI is a prognostic biomarker for OS in MICC patients, and it is more sensitive in males than in females.