Visceral Obesity and Colorectal Cancer: Are We Missing the Boat with BMI?

INTRODUCTION: Compared to subcutaneous fat, visceral fat is more metabolically active, leading to chronic inflammation and tumorigenesis. The aim of this study is to describe the effect of visceral obesity on colorectal cancer outcomes using computed tomography (CT) imaging to measure visceral fat. MATERIALS AND METHODS: We conducted a retrospective chart review of patients who underwent surgical resection for colorectal cancer. Visceral fat volume was measured by preoperative CT scans. Final analysis was performed by stratifying patients based on oncologic stage. RESULTS: Two hundred nineteen patients met the inclusion criteria, 111 viscerally obese and 108 nonobese. Body mass index (BMI) weakly correlated with visceral fat volume measurements (R (2) = 0.304). Whereas obese patients had no difference in survival when categorizing obesity by BMI, categorizing based on visceral fat volume resulted in significant differences in stage II and stage III patients. In stage II cancer, viscerally obese patients had a nearly threefold decrease in disease-free survival (hazard ratio (HR) = 2.72; 95 % confidence interval (CI) = 1.21, 6.10). In stage III cancer, viscerally obese patients had a longer time to recurrence (HR = 0.39; 95 % CI = 0.16, 0.99). CONCLUSION: This study shows that viscerally obese patients with stage II colorectal cancer are at higher risk for poor outcomes and should be increasingly considered for adjuvant chemotherapy.