Background
Malnutrition after esophageal cancer surgery is associated with reduced health-related qualify of life. Therefore, a prediction model identifying patients at risk for severe weight loss after surgery was developed.

Methods
Data from a Swedish population-based cohort study, including 616 patients undergoing esophageal cancer surgery in 2001–2005, was used. Candidate predictors included risk factors available before and immediately after surgery. Severe weight loss was defined as ≥ 15% loss of body weight between the time of surgery and 6 months postoperatively. The prediction model was developed using multivariable models. The accuracy of the model was measured by the area under the receiver operating characteristics curve (AUC) with bootstrap validation. The model was externally validated in a hospital-based cohort of 91 surgically treated esophageal cancer patients in the United Kingdom in 2011–2016. Each predictor in the final model was assigned a corresponding risk score. The sum of risk scores was equivalent to an estimated probability for severe weight loss.

Results
Among the 351 patients with 6 months follow-up data, 125 (36%) suffered from severe postoperative weight loss. The final prediction model included body mass index at diagnosis, preoperative weight loss, and neoadjuvant therapy. The AUC for the model was 0.78 (95% CI 0.74–0.83). In the validation cohort, the AUC was 0.76. A clinical risk assessment guide was derived from the prediction model.

Conclusions
This prediction model can preoperatively identify individuals with high risk of severe weight loss after esophageal cancer surgery. Intensive nutritional interventions for these patients are recommended.

Nutritional problems are common in esophageal cancer patients, with a significant proportion of patients already suffering from severe weight loss at diagnosis.1, 2, 3 Malnutrition after extensive gastrointestinal surgery has been associated with poor postoperative recovery, reduced survival rate, and deterioration in health-related quality of life (HRQOL).4, 5, 6, 7 The underlying cause of such malnutrition is complex and multifactorial. The primary symptom of esophageal cancer is progressive dysphagia, caused by an obstructing tumor.3,8 This may lead to the increased basal metabolism not being met due to insufficient caloric intake, which results in weight loss. The weight loss also can be related to the cancer treatment. Chemoradiotherapy, which often is included in the esophageal cancer treatment, can contribute to catabolic muscle loss.9,10 During esophagostomy, a large part of the stomach is reconstructed into a tube, which replaces the removed esophagus and upper stomach.11 This may lead to the normal capacity of the stomach being lost. The altered anatomy with the missing reservoir function is usually accompanied by physiological issues with pancreatic insufficiency and/or gastric dumping syndrome and often presents as eating difficulties.12 There also is a psychological aspect of the problem, where the diagnosis and treatment can result in depressive symptoms, which may in turn further reduce appetite.5 To prevent or reduce such involuntary weight loss, a method for identifying patients at risk at an early postoperative stage would be beneficial for tailored follow-up planning. The at-risk patients could then be further screened to plan individually for nutritional support in those with poor nutritional status.13,14 The purpose of this study was to develop and externally validate a prediction model identifying patients at risk for severe weight loss after esophageal cancer surgery, by using objective parameters measured preoperatively or immediately after surgery.