Surgical treatment of gastric cancer is associated with a high risk of perioperative complications. Morbidity of cancer patients increases in concert with the clinical stage of the malignancy. It is postulated that a reduction in perioperative morbidity and improved quality of life of patients with advanced gastric cancer can be achieved by proper preparation to surgery, among others. One of such methods is the implementation of immunostimulating nutritional therapy during the perioperative period.The stage of cancer will be graded according to TNM classification. The patients will be randomly assigned to four clinical groups based on the type of nutritional therapy implemented.