Gastric cancer is the fifth most common cancer and the third most common cause of cancer-related death globally.
1 In Western countries, patients with operable gastric or gastroesophageal adenocarcinoma frequently undergo neoadjuvant or perioperative chemotherapy before surgical resection.
2,3 This adjunctive chemotherapy is associated with a modest benefit in terms of overall survival (OS) compared with surgery alone but also with toxic effects, including neutropenia and thromboembolic disease. Unfortunately, after optimal multimodality therapy, approximately half of patients undergoing resection will relapse and die of their cancer. There are no validated prognostic biomarkers for patients with gastroesophageal cancer who receive neoadjuvant treatment, and current patient selection is based purely on preoperative radiologic staging.