Higher visceral fat area/subcutaneous fat area ratio measured by computed tomography is associated with recurrence and poor survival in patients with mid and low rectal cancers

Obesity is thought to influence postoperative complications and recurrence of mid and low rectal cancer (MLRC) because of intraoperative technical difficulties. However, few reports have described the relationship between obesity indices and the clinical outcomes of MLRC. This study aimed to investigate the association between visceral obesity on computed tomography (CT) and oncolofical outcomes after surgery for MLRC and identify the obesity index that most accurately reflects clinical outcomes. We investigated 125 patients who underwent curative resection for MLRC between 2004 and 2010. Visceral fat area (VFA) was defined as the umbilicus-level intra-abdominal adipose tissue area measured by CT. Body mass index (BMI), total fat area, VFA, subcutaneous fat area (SFA) and VFA/SFA ratio (V/S ratio) were analysed. The median follow-up time was 60.3 months (range, 38.2-122.6 months). Recurrence was detected in 28 (22.4%) patients. Among the various obesity indices, recurrence was significantly associated with V/S ratio only (1.02 +/- 0.45 versus 0.86 +/- 0.34; P = 0.046). Stage, preoperative carcinoembryonic antigen level, V/S ratio, lymphatic invasion and perineural invasion were significantly associated with recurrence on univariate analysis, while only V/S ratio (P = 0.019; 95% confidence interval, 1.22 to 9.09) was significantly associated with recurrence on multivariate analysis. Disease-free and overall survival of the obese group (V/S ratio > 1.0) were shorter than those of the non-obese group. V/S ratio is the optimal obesity index for predicting stage I-III MLRC recurrence.