Inclusion Criteria:  Histologically or cytologically confirmed locally advanced resectable adenocarcinoma of the esophagogastreal junction or the stomach at the stage of cT2-T4aN+M0 (AJCC 8th) without distant metastases and without infiltration of adjacent structures and organs. Age ≥ 18 years. Willing to provide residual tumor tissues after routine clinical diagnosis for tumor microenvironment detection analysis. Patients agree to participate in the study and sign the informed consent. Patients need to receive perioperative drug therapy.  Exclusion Criteria:  -