Inclusion Criteria:  Male or Female patients aged 18 years and older Histologically proven primary gastric adenocarcinoma before surgery Clinical stage is locally advanced cT2-4a any N and M0 In initial evaluation, patient can undergo radical gastrectomy and lymphadenectomy No preoperative therapy, including chemotherapy and radiotherapy No known cancer diagnosis within last five years Signed informed consent  Exclusion Criteria:  Gastrectomy cannot be achieved during operation due to metastasis Patient fails to follow-up and provide postoperative samples