Impact of body mass index on long-term survival outcome in Asian populations with solid cancer who underwent curative-intent surgery: A six-year multicenter observational cohort study

Purpose: Being elevated body mass index (BMI) has been considered a poor prognostic factor in patients with cancer. However, studies about the impact of elevated BMI on the survival outcome after cancer surgery have conflicting results. This study aimed to evaluate the impact of BMI on long-term postoperative survival outcome in a large cohort of Asian population with solid cancers. Methods: A total of 33,551 patients who underwent curative-intent surgery for solid cancers between January 2007 and December 2012 at four hospitals in Taiwan were included. BMI was analyzed using univariate and multivariate regression analyses to determine its association with survival outcome. Results: With a median follow-up of 43.8 (range, 1-91) months, the rate of all-cause mortality was 21.7% (n=7264 patients), while that of cancer-related mortality was 13.4% (n=4499 patients). BMI was a significant prognostic factor in multivariate analysis for overall survival (OS) and cancer-specific survival (CSS). The adjusted hazard ratio (HR) per kg/m(2) was 0.922 (95% confidence interval [CI], 0.916-0.929; P<0.001) and 0.932 (95% CI, 0.924-0.940; P<0.001) for OS and CSS, respectively. Patients with BMI <17 kg/m(2) had the highest postoperative mortality risk, with a hazard ratio of 3.8-fold higher for OS and 5.0-fold higher for CSS than those with BMI >35 kg/m(2). Conclusions: This study showed that BMI was positively associated with survival outcome in patients with cancer who underwent radical surgery. BMI was an independent prognostic factor and can be used to risk stratify patients in Asians with solid cancers.