Influence of Body Mass Index on Long-Term Outcome in Patients with Rectal Cancer—A Single Centre Experience

Background: Excess bodyweight is known to influence the risk of colorectal cancer; however, little evidence exists for the influence of the body mass index (BMI) on the long-term outcome of patients with rectal cancer. Methods: We assessed the impact of the BMI on the risk of local recurrence, distant metastasis and overall—survival in 612 patients between 2003 and 2010 after rectal cancer diagnosis and treatment at the University Hospital Erlangen. A Cox-regression model was used to estimate the hazard ratio and multivariate risk of mortality and distant-metastasis. Median follow up-time was 58 months. Results: Patients with obesity class II or higher (BMI ≥ 35 kg/m(2), n = 25) and patients with underweight (BMI < 18.5 kg/m(2), n = 5) had reduced overall survival (hazard ratio (HR) = 1.6; 95% confidence interval (CI) 0.9–2.7) as well as higher rates of distant metastases (hazard ratio HR = 1.7; 95% CI 0.9–3.3) as compared to patients with normal bodyweight (18.5 ≤ BMI < 25 kg/m(2), n = 209), overweight (25 ≤ BMI <30 kg/m(2), n = 257) or obesity class I (30 ≤ BMI <35 kg/m(2), n = 102). There were no significant differences for local recurrence. Conclusions: Underweight and excess bodyweight are associated with lower overall survival and higher rates of distant metastasis in patients with rectal cancer.