Perioperative chemotherapy (CHT) or CHT/RT combined with surgery is the standard therapeutic approach for the treatment of locally advanced cancer of the esophagus, gastroesophageal junction (GEJ), and stomach. Comprehensive cancer treatment is associated with high perioperative morbidity and mortality. Serious postoperative complications occur in up to 20-80% of patients undergoing esophagectomy. The impact of nutritional status and overall physical condition on surgical outcomes and overall treatment has been demonstrated many times. The concept of pre-rehabilitation/pre-optimization, which involves establishing an individualized nutritional plan, monitoring and managing physical activity, and providing comprehensive supportive oncological and psychological care as early as during neoadjuvant CHT or CHT/RT, is a prerequisite for improving perioperative and 30-day postoperative morbidity and mortality.