The impact of pre- and post-operative weight loss and body mass index on prognosis in patients with oesophageal cancer

Background: Weight loss is a cardinal symptom of oesophageal cancer and is often continued after surgery. High body mass index (BMI) is a strong risk factor for oesophageal adenocarcinoma. This study aimed to assess the impact of pre- and post-operative weight loss and BMI on long-term mortality after resection for oesophageal cancer. 
Methods: This prospective and nationwide cohort study included 390 patients, operated on for oesophageal cancer in Sweden in 2001-2005 with follow-up until 2016, who responded to a questionnaire on weight history 6 months after surgery. Multivariable Cox proportional hazard models provided hazard ratios (HRs) and 95% confidence intervals (95% CIs) of mortality while adjusting for several prognostic factors, including tumour stage. 
Results: Compared to weight stable patients, pre-surgery weight loss indicated increased HRs of overall all-cause mortality (HR=1.32, 95% CI 0.94-1.86) and disease-specific mortality (HR=1.36, 95% CI 0.93-1.98). Patients with >20% weight loss post-surgery had worse overall all-cause mortality (HR=1.71, 95% CI 1.01-2.88) and disease-specific mortality (HR=2.20, 95% CI 1.24-3.89). Compared to patients with normal BMI, decreased HRs were indicated for patients who were obese at the time of surgery (overall all-cause mortality HR 0.87 95% CI, 0.58-1.31 and disease-specific mortality HR=0.89, 95% CI 0.57-1.40), while patients with BMI ≤19.9 at 6 months post-surgery had increased all-cause mortality (HR=1.41, 95% CI 1.03-1.95) and disease-specific mortality (HR=1.55, 95% CI 1.09-2.21). 
Conclusion: Post-operative weight loss and low BMI at 6 months post-surgery are independent markers of poor prognosis in patients who undergo surgery for oesophageal cancer.