Impact of body mass index on overall survival after surgery for colorectal cancer

Abstract

Purpose The studies on the impact of obesity on survival for colorectal cancer (CRC) in Korea are still insufficient. The aim of this study is to evaluate body mass index (BMI) as a prognostic factor of CRC. Methods From January 2006 to December 2008, a total of 1873 patients with CRC who underwent surgery at Seoul National University Hospital were included in this study. Study participants were divided into five BMI groups: underweight (<18.5 kg/m2), normal weight (18.5–22.9 kg/m2), overweight (23–24.9 kg/m2), obese (25–29.9 kg/m2) and morbidly obese (≥30 kg/m2). Clinicopathological variables and survival data were reviewed retrospectively. Overall survival was analyzed using log-rank test and Cox regression analysis. Results Overall survivals of underweight, normal weight, overweight, obese, and morbidly obese groups were significantly different (5-year overall survivals rates: 54.4%, 73.2%, 78.6%, 77.2%, and 53.8%, respectively; P<0.001). In multivariable analysis for overall survival, BMI was an independently significant risk factor. Normal weight, overweight, and obese groups had lower hazard ratios for overall survival than underweight group (hazard ratio [HR], 0.626; 95% confidence interval [CI], 0.462–0848, P=0.002; HR, 0.530, 95% CI, 0.377–0.744, P<0.001; HR, 0.511, 95% CI, 0.470–1.675, P<0.001, respectively). The hazard ratio of morbid obese group was not significantly different from that of underweight group (HR=0.887, 95% CI=0.470–1.675, P=0.712). Conclusion BMI can be a prognostic factor for CRC in Korea. Underweight and morbidly obese were associated with poor overall survival. Large multicenter studies in the Korean population is needed for a definite conclusion.

Keywords

• body mass index
• thinness
• overweight
• obesity
• colorectal neoplasms
• survival