The objective of this observational study was to gain a deeper understanding of the epidemiology of the disease in Hungary through a broad analysis of patients with new-onset esophageal-oesophageal-stomach junction tumors, and to identify key parameters that could potentially influence the outcome of the disease and are closely correlated with morbidity and mortality. The investigators' primary objective is to identify potential factors and conditions that could be influenced and modified to enhance the disease outcome. Main questions: 1. What are the measurable changes in performance, workload, nutritional status, cardiac function, mental status in the patients studied? 2. What is the time course of the changes during and after treatment? 3. Which pathological parameters are associated with disease outcome and which are potential points of intervention to improve the course of the disease? Patients will undergo a detailed physical and nutritional assessment, non-invasive imaging tests and several questionnaires in addition to the usual pre- and post-operative examinations.