The study is a real-world observational clinical study. Patients diagnosed as gastric cancer through histopathology were screened and enrolled. Before anti-tumor treatment, gastroscopy biopsy tissue specimens, surgical specimens, and malignant pleural effusion or ascites specimens, etc. are collected. The investigators will perform a drug sensitivity testing based on a novel drug susceptibility testing method to test the commonly used anti-tumor treatment regimens. Patients were given conventional anti-tumor treatment according to the medical judgment of the doctors. Finally, the investigator will evaluate the consistency of clinical efficacy in gastric cancer treatment and drug susceptibility outcomes.

Inclusion Criteria:

1. Male or female, aged ≥ 18 and ≤80;
2. Patients with gastric cancer diagnosed by histopathology;
3. Patients who need neoadjuvant treatment; adjuvant therapy after radical surgery or palliative treatment;
4. Fresh tumor tissue specimens or malignant pleural effusion or ascites can be obtained;
5. Patients who sign the informed consent form, and are able to comply with the study period treatment process.

Exclusion Criteria:

1. Inability to follow the research protocol;
2. Inability to obtain relevant fresh specimens by biopsy/surgery/puncture;
3. Concomitant contraindications to chemotherapy;
4. pregnant or lactating women;
5. Patients deemed inappropriate by investigators.

patients with gastric cancer in the First Affiliated Hospital of China Medical University