Perioperative Leucovorin, Oxaliplatin, Docetaxel and S-1 (LOTS) For Locally Advanced Gastric or Gastroesophageal Junction Cancer

Inclusion Criteria: 1. Subjects have histologically-confirmed gastric or gastroesophageal junction (classified as Siewert type III) adenocarcinoma with a clinical stage of T3 or above, lymph node involvement (N+) or both according to American Joint Cancer Committee staging system, 8th edition (AJCC 8th). 2. Subjects present with at least one measurable lesion which can be accurately assessed by conventional techniques at least 2.0 cm or 1.0 cm by computed tomography (CT) or magnetic resonance imaging (MRI). 3. Subjects have a lymph node-positive disease in which that at least one of the nodes with a diameter greater or equal to 0.8 cm in the long axis. If subjects do not have a node-positive disease, a clinical stage of T3 or above and a measurable tumor is required for inclusion. 4. Subjects are above 20 years of age with an Eastern Cooperative Oncology Group (ECOG) performance status ≤1, have a life expectancy \>3 months, have surgically resectable disease and are physically competent and willing to receive a curative operation. 5. Subjects have adequate organ functions, including bone marrow reserve with a leukocyte count ≥3,000 /µL and platelet count ≥100,000 /µL, hepatic reserve with a serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤3 times of upper limits and total bilirubin ≤2.0 mg/dL, renal reserve with a creatinine clearance ≥60 mL/min and cardiac reserve with a left ventricular ejection fraction (LVEF) ≥50% by echocardiography at baseline. 6. Subjects have, or agree to establish a vascular access that permits systemic intravenous chemotherapy and are capable of ingesting capsules per oral. 7. Subjects with reproductive potentials are willing to accept contraceptive measures during the trial. 8. Subjects are functionally and cognitively capable to be informed of the trial contents and objectives (including obtaining blood and tumor tissue for the trial investigation), and agree to sign the written consent for enrollment. Exclusion Criteria: 1. Subjects have metastatic (M1, including washing cytology positive for peritoneal carcinomatosis), recurrent gastric/gastroesophageal junction cancer (defined by an interval time less than five years from the current diagnosis to the prior initial disease), or any other underlying primary malignancies excluding carcinoma in situ or resectable skin cancer. 2. Subjects have received chemotherapies within 2 years, or a major abdominal surgery or radiotherapy within 4 weeks before the trial enrollment. 3. Subjects are known to be allergic to any of the studied chemotherapeutics. 4. Subjects have underlying chronic illnesses, including cardiopulmonary diseases, ischemic heart disease, inflammatory bowel disease, poorly-controlled diabetes mellitus, liver cirrhosis and/or peripheral neuropathy of any etiologies. 5. Subjects have active bacterial, viral, fungal or mycobacterial infections that require systemic therapy, including active infection with human immunodeficiency virus (HIV), hepatitis B or C virus (HBV or HCV) 6. Subjects are planning to conceive or already in pregnancy or breastfeeding. 7. Subjects are currently participating in any other clinical trials or studies.