Prospective Observational Cohort Study

Inclusion Criteria: * aged ≥18 years * gastric primary lesions confirmed by pathology and liver metastases confirmed by pathology or imaging (before, during, or after initial treatment) * expected survival time of ≥ 12 weeks * Eastern Cooperative Oncology Group Physical Status Score (ECOG PS score) of 0-2 * signed informed consent * good compliance and ability to complete regular follow-up Exclusion Criteria: * heterochronous liver metastases * multi-centra clinics with significant missing case information * diagnosed, suspected or active autoimmune disease * history of immunodeficiency * history of allogeneic organ and haematopoietic stem cell transplantation * pregnant or breastfeeding female patients * uncontrolled co-morbidities, including but not limited to: * a.HIV-infected (HIV-positive) patients * b.severe infections that are active or poorly controlled clinically * c.evidence of severe or uncontrolled systemic disease * \- severe psychiatric disease * \- severe neurological disease * \- epilepsy * \- dementia * \- unstable or uncompensated respiratory * \- cardiovascular * \- hepatic disease * \- renal disease * \- uncontrolled hypertension * Abnormal coagulation in people with active bleeding or new thrombotic disease, on therapeutic doses of anticoagulants, or with bleeding tendencies.