Total Neoadjuvant FLOT Chemotherapy in Locally Advanced Gastric and Gastroesophageal Junction Cancer

Inclusion Criteria: * Tumor spread according to TNM: ≥cT3 and/or ≥cN0 and M0 (except of invasion of the common hepatic artery, celiac trunk, proximal part of the splenic artery, aorta, head of the pancreas); * Performance status by Eastern Cooperative Oncology Group (ECOG): 0 - 1; * Histologically confirmed gastric adenocarcinoma or gastroesophageal junction (Siewert type 2/3) adenocarcinoma. * Differentiation grade: G0 - G4; * Tumor localization: cardio-esophageal junction (Siewert 2, 3), cardiac part of the stomach, body of the stomach, antral part of the stomach, pyloric part of the stomach; * Tumor extension: esophagus, diaphragm, liver, body and tail of the pancreas, anterior abdominal wall, small and large intestine, distal part of the splenic artery, spleen; * Patient agrees to participate in this biomedical study. Exclusion Criteria: * Presence of another oncological disease at a different site if less than 5 years have passed since radical treatment. * Comorbidities or patient conditions that preclude the administration of chemotherapy.