Evaluating Long-Term Survival of Patients with Esophageal Cancer using Parametric Non-Mixture Cure Rate Models

Background & Objective: Esophageal cancer (EC) has been identified as one of the most common cancers in the northeastern regions of Iran. In our study, parametric non-mixture cure rate model was applied to evaluate the effects of risk factors on the long-term survival of patients with EC in East Azerbaijan, Northeastern Iran. Materials & Methods: This retrospective cohort study of 127 patients with EC registered at Iran National Cancer Registry office in the period 2009-2010. These patients were followed up for 5 years in East Azerbaijan, Iran until 2015. The best parametric cure rate model was identified and the risk factors of survival in patients with EC were measured by Akaike Information Criteria and parametric non-mixture cure rate model, respectively. Results: The survival time of EC patients ranged 0.10-69.03 months. Male sex (Odds Ratio (OR) =0.08, 95% confidence interval (CI: 0.02-0.32, P<0.001), patients who underwent esophagectomy surgery (OR=6.11, 95%CI: 1.46-25.55, P=0.013) had a significant effect on the survival and the cure fraction of EC patients. Population cure rate was 0.11 (95%CI: 0.07-0.19) and cure fraction was estimated 4.9%. Conclusion: The Weibull non-mixture cure rate model was the most appropriate statistical tool to identify potential risk factors that affect both survival and cure fraction of EC patients. It is a recommended tool for analyzing the long-term survival of patients with EC.