HIPEC Combined With Sintilimab for Gastric Cancer With Peritoneal Metastasis

Inclusion Criteria: 1. Advanced gastric (gastroesophageal junction) adenocarcinoma confirmed by histology; 2. Age 18-75 years, Male or Non pregnant female 3. ECOG (Eastern Cooperative Oncology Group) : 0\~1； 4. Negative for HER-2 by IHC/FISH； 5. Peritoneal metastasis is confirmed by laparoscopic exploration, and the PCI≤20； 6. Untreated (e.g. radiotherapy, chemotherapy, target therapy and immunotherapy); 7. Normal Bone marrow, liver and kidney function indices before the recruitment: 8. Expected survival≥ 12 week 9. Signed the Informed Consent Form, and blood and tissue samples can be obtained; Exclusion Criteria: 1. Other distal metastases besides peritoneal metastases (e.g., liver, lung, pleural, brain, bone metastases, etc.); 2. Previous systemic therapy for gastric cancer; 3. Recurrent gastric cancer after surgery; 4. Cardiopulmonary dysfunction; 5. Immunosuppressive drugs(eg.Corticosteroids) were used within 14 days before treatment, eg.corticosteroids, 6. There is any active autoimmune disease or a history of autoimmune disease (including but not limited to: autoimmune hepatitis, interstitial pneumonia, uveitis, enteritis, hepatitis, hypophysitis, vasculitis, nephritis, hyperthyroidism, hypothyroidism; subjects with vitiligo or asthma in childhood have been completely relieved, and those who do not need any intervention after adulthood can be included Asthma requiring medical intervention with bronchodilator was not included.) 7. Allergy to the drugs in this protocol； 8. Patients with other diseases not suitable for inclusion, such as immune deficiency, active tuberculosis, hepatitis B (non-active hepatitis B surface antigen (HBsAg) carriers, hepatitis B virus titer \<500IU/ml after treatment and with normal liver function can be included), hepatitis C virus positive; 9. A history of idiopathic pulmonary fibrosis, tissue pneumonia, drug pneumonia, idiopathic pneumonia, or r active pneumonia; 10. Other patients who were considered unsuitable for inclusion by the researchers;