Association of Body Mass Index with Survival in Asian Patients with Colorectal Cancer.

Purpose The clinical significance of body mass index (BMI) on long-term outcomes has not been extensively investigated in Asian patients with colorectal cancer (CRC). This study aims to describe the association between BMI and survival, plus providing BMI cut-off value for predicting prognosis in CRC patients. Materials and Methods A total of 1,182 patients who had undergone surgery for stage I-III CRC from June 2004 to February 2014 were included. BMI was categorized into four groups based on the recommendation for Asian ethnicity. The optimal BMI cut-off value was determined to maximize overall survival (OS) difference. Results In multivariable analysis, underweight BMI was significantly associated with poor OS (hazard ratio [HR] = 2.38, 95% confidence interval [CI] = 1.55-3.71, p<0.001) and obese BMI was associated with better OS (HR = 0.72, 95% CI = 0.53-0.97, p=0.036) compared with the normal BMI. Overweight and obese BMI were associated with better recurrence-free survival (RFS) (HR = 0.64, 95% CI = 0.42-0.99, p=0.046; HR = 0.58, 95% CI = 0.38-0.89, p=0.014, respectively) compared with the normal BMI group. BMI cut-off value was 20.44 kg/m2. Adding the BMI cut-off value to cancer staging could increase discriminatory performance in terms of integrated area under the curve and Harrell's concordance index. Conclusion Compared to normal BMI, underweight BMI was associated with poor survival whereas obese BMI was associated with better survival. BMI cut-off value of 20.44 kg/m2 is a useful discriminator in Asian patients with CRC.