The association between body mass index and postoperative complications, 30-day mortality and long-term survival in Dutch patients with colorectal cancer.

INTRODUCTION: This retrospective study aims to examine the association between body mass index (BMI) and serious postoperative complications, 30-day mortality and overall survival in colorectal cancer (CRC) patients.

MATERIALS AND METHODS: All CRC patients diagnosed between 2008 and 2013 in the south-eastern part of the Netherlands were included. Patients were categorized into four BMI groups: underweight (<18.5), normal weight (18.5 ≥ BMI<25), overweight (25 ≥ BMI<30), and obese (≥30).

RESULTS: A total of 7371 CRC patients were included (underweight 133 (1.8%); normal weight 2054 (41.4%); overweight 2955 (40.1%); obesity 1229 (16.7%)). Underweight patients were more likely to have postoperative complications (18.8% vs. 11.7%, adjusted OR 1.95, 95% CI 1.08-3.49) and had a worse 30-day mortality (9.8% vs. 3.3%, adjusted OR 4.37, 95% CI 2.03-9.42) compared to normal weight patients. After stratification for stage (stage I-III and stage IV), underweight was associated with a worse overall survival in both groups compared to normal weight (stage I-III: HR 2.06, 95%CI 1.51-2.80; stage IV: HR 1.65, 95% CI 1.11-2.45). Overweight was associated with an improved overall survival compared to normal weight in both stage groups. Only in stage IV patients obesity was associated with a significant better overall survival compared to stage IV normal weight patients.

CONCLUSION: Underweight CRC patients were more likely to have postoperative complications and a worse 30-day mortality compared to patients in other BMI categories. The underweight population also has a worse long-term survival while overweight CRC patients and obese stage IV CRC patients were associated with an improved survival compared to normal weight patients.