Lower body mass index predicts worse cancer-specific prognosis in octogenarians with colorectal cancer

Abstract

High body mass index (BMI) is a risk factor for colorectal cancer. However, the prognostic impact of BMI and other factors may differ between elderly and younger colorectal cancer patients. We analyze here prognostic factors in the surgical management of octogenarians with colorectal cancer and clarify the prognostic impact of BMI. Cox regression analysis and propensity score methods were used to retrospectively examine the association of BMI with mortality in 1613 octogenarian patients who underwent curative surgery for stage 0-III colorectal cancer. In the Cox regression analysis, lower BMI (<18.5kg/m(2); p=0.001), age≥83years (p=0.008), American Society of Anesthesiology class≥3: (p=0.001), performance status≥2 (p=0.003), Union for International Cancer Control (UICC) stage≥III (p=0.001), and postoperative adverse events (p=0.001) were independently associated with decreased overall survival. Lower BMI (p=0.001) and UICC stage≥III (p=0.001) were independently associated with decreased cancer-specific survival. After covariate adjustment, lower BMI was a risk factor for overall [hazard ratio (HR) 1.62; 95% confidence interval (CI) 1.26-2.05; p=0.0004] and cancer-specific survival (HR 2.00; 95% CI 1.39-2.87; p=0.0038) compared with normal BMI (18.5-24.9kg/m(2)). Lower BMI is significantly and independently associated with increased mortality risk in octogenarians who undergo curative surgery for colorectal cancer. Lower BMI should be used for prognosis assessment in octogenarians with colorectal cancer.