Assessing Malnutrition Before Major Oncologic Surgery: One Size Does Not Fit All

Background: There are multiple definitions for malnutrition, without evidence of superiority of any one definition to assess preoperative risk. Therefore, to aid in identification of patients that might warrant prehabilitation, we aimed to determine the optimal definition of malnutrition before major oncologic resection for 6 cancer types. Methods: The American College of Surgeons NSQIP database was queried for patients undergoing elective major oncologic operations from 2005 to 2017. Nutritional status was evaluated using the European Society for Parenteral and Enteral Nutrition definitions, NSQIP's variable for >10% weight loss during the previous 6 months, and the WHO BMI classification system. Multivariable logistic regression was performed to evaluate the adjusted effect of nutritional status on mortality and major morbidity. Results: We identified 205,840 operations (74% colorectal, 10% pancreatic, 9% lung, 3% gastric, 3% esophageal, and 2% liver). A minority (16%) of patients met criteria for malnutrition (0.6% severe malnutrition, 1% European Society for Parenteral and Enteral Nutrition 1, 2% European Society for Parenteral and Enteral Nutrition 2, 6% NSQIP, and 6% mild malnutrition), 31% were obese, and the remaining 54% had a normal nutrition status. Both mortality and major morbidity varied significantly between the nutrition groups (both p < 0.0001). An interaction between nutritional status and cancer type was observed in the models for mortality and major morbidity (interaction term p < 0.0001 for both), indicating the optimal definition of malnutrition varied by cancer type. Conclusions: The definition of malnutrition used to assess postoperative risk is specific to the type of cancer being treated. These findings can be used to enhance nutritional preparedness in the preoperative setting.