Inclusion Criteria:  Patients with histologically proven adenocarcinoma of the EGJ (Siewert II-III) or stomach. Preoperative staging: cT2-T4a, cN0-N3, M0. Patients >18 years old. Patients undergoing perioperative chemotherapy with Docetaxel, oxaliplatin, leucovorin, and 5-fluorouracil (FLOT).  Exclusion Criteria:  Siewert I EGJ tumor Patients undergoing preoperative radiotherapy. Absence of both pre and post-chemotherapy CT-scan. Patients with tumor progression during preoperative chemotherapy. Patients undergoing other neoadjuvant chemotherapy regimen different from FLOT Exploratory laparoscopy with positive cytology on the peritoneal lavage or evidence of peritoneal carcinosis