Impact of body mass index as a continuous variable on short- and long-term outcomes in patients undergoing laparoscopic surgery for colon cancer.

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) 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,  < 0.05) and blood loss (odds ratio: 1.089, 95% CI: 1.032-1.149,  < 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 versus those with BMI <28.5 kg/m (hazard ratio: 0.682, 95% CI: 0.462-1.008,  = 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), suggesting that the prognosis for highly obese colon cancer patients appears to follow the obesity paradox.