SEOM-GEMCAD-TTD clinical guideline for the diagnosis and treatment of gastric cancer (2023).

Gastric cancer (GC) is the fifth most common cancer worldwide with a varied geographic distribution and an aggressive behavior. In Spain, the incidence is lower and GC represents the tenth most frequent tumor and the seventh cause of cancer mortality. Molecular biology knowledge allowed to better profile patients for a personalized therapeutic approach. In the localized setting, the multidisciplinary team discussion is fundamental for planning the therapeutic approach. Endoscopic resection in very early stage, perioperative chemotherapy in locally advanced tumors, and chemoradiation + surgery + adjuvant immunotherapy for the GEJ are current standards. For the metastatic setting, biomarker profiling including Her2, PD-L1, MSS status is needed. Chemotherapy in combination with checkpoint inhibitors had improved the outcomes for patients with PD-L1 expression. Her2 positive patients should receive antiHer2 therapy added to chemotherapy. We describe the different evidences and recommendations based on the literature.