Abstract
BACKGROUND: The impact of obesity on colon cancer remains unclear. Very few studies of colon cancer surgery have analyzed body mass index (BMI) as a continuous variable, with no such reports from Japan. This study examined the association between BMI as a continuous variable and short- and long-term outcomes of laparoscopic surgery for obese colon cancer patients. METHODS: Obese (BMI ≥25 kg/m(2)) patients who underwent laparoscopic radical surgery for Stage II/III colon cancer at 46 participating centers from 2009 to 2013 were included. Associations between short- and long-term outcomes and BMI as a continuous variable were analyzed by univariate and multivariate regression models. RESULTS: Among patients meeting the study criteria, 1036 were examined. BMI as a continuous variable correlated with log-transformed operative time (regression coefficient: 0.02, 95% confidence interval [CI]: 0.012-0.028, p < 0.05) and blood loss (odds ratio: 1.089, 95% CI: 1.032-1.149, p < 0.05). There was no association between BMI continuous variables and 3-year relapse-free survival (RFS) and overall survival. However, 3-year RFS was possibly better in patients with BMI ≥28.5 kg/m(2) versus those with BMI <28.5 kg/m(2) (hazard ratio: 0.682, 95% CI: 0.462-1.008, p = 0.055). CONCLUSIONS: This study showed that BMI as a continuous variable correlated with operative time and blood loss. RFS was possibly better in the severely obese patients (BMI ≥28.5 kg/m(2)), suggesting that the prognosis for highly obese colon cancer patients appears to follow the obesity paradox.