Impact of obesity on surgical and oncological outcomes in the management of colorectal cancer

Introduction: Obesity is an established risk factor for colorectal cancer, particularly in males, and may negatively impact on oncologic outcomes. The aim of this study was to examine the impact of body mass index (BMI) on mortality and morbidity, tumour pathology, and overall survival in a consecutive cohort of Irish colorectal cancer patients treated with curative intent. Methods: A retrospective analysis of BMI data entered prospectively into a comprehensive electronic database of colorectal cancer patients was undertaken. Patients were excluded if they had emergency surgery, previous malignancy or the BMI was not recorded. Analysis was performed comparing genders, obese with non-obese and comparing BMI categories. Results: Of the 414 patients, 10% were underweight (<20 kg/m²); 35% were normal weight (20-25 kg/m²); 37% were overweight (25-30 kg/m²), and 18% were obese (30.00 kg/m ²). Obesity overall was not significantly associated with pathological stage (p∈=∈0.099) or positive lymph node status (p∈=∈0.109) or degree of nodal involvement (p∈=∈0.068). Obesity was significantly (p<0.05) associated with more advanced pathological stage, node positivity and degree of nodal involvement in male only and colon cancer only analysis. There was no difference in the overall incidence of major (p∈=∈0.244) and minor complications (p∈=∈0.078) when comparing obese with non-obese, but pelvic abscesses were more common in obese patients (p∈=∈0.037). The underweight cohort had a higher rate of major complications (p∈=∈0.041), sepsis (p∈=∈0.024) and post-operative death (p∈=∈0.006). Survival was equivalent between BMI categories and obese and non-obese groups (p∈=∈0.469). Conclusion: Obesity was associated with more advanced tumours in males and in colon cancer patients only and with a higher risk of post-operative pelvic abscesses but no significant differences with non-obese cohorts in the main outcome measures of in-hospital mortality, major morbidity and survival. Conversely, the adverse consequences of under-nutrition were highlighted in this study.