Prognostic Significance of Adipose Tissue Distribution and Metabolic Activity in PET / CT in Patients with Metastatic Colorectal Cancer

Abstract Purpose: In this study, we aimed to evaluate prognostic significance of adipose tissue distribution and metabolic activity in PET/CT to predict survival in patients with metastatic colorectal cancer (mCRC).Methods: The volume, density (HU) and FDG uptake (standardized uptake value-[SUV]) of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) and maximum FDG uptake of the tumor tissue were measured. Subcutaneous adipose tissue of volume-to-density ratio (SAT ratio) was calculated.Results: The median OS for the patients with SAT ratio value <-1.1 and ≥ -1.1 were 38.5 (95% CI 31.54-45.58) and 24.5 (95% CI 14.13-34.93) months, respectively (p=0.05). During follow up, 69 patients experienced disease progression. The median progression-free survival (PFS) was 11.03 months (95% CI: 9.11-12.95). Median PFS for patients with tumor SUV max value <11.5 and ≥11.5 were 9.2 (95% CI 7.25-11.27) and 12.6 (95% CI 10.02-15.27) months, respectively (p=0.14). 48 patients received bevacizumab therapy. VAT SUV mean (HR: 0.09; 95% CI 0.01-0.52, p=0.008) was significantly associated with PFS in patients receiving bevacizumab. SAT ratio was the significant parameter for the OS (HR: 0.58; 95% CI 0.33-1.01, p=0.05) and PFS (HR: 1.99; 95% CI 1.02-3.91, p=0.043).Conclusions: SAT ratio was an independent prognostic factor for survival in patients with mCRC. Higher SAT volume is correlated with longer survival in mCRC patients