This is a multi-center, prospective and observational clinical study. Eligible patients will accept generalized chemotherapy according to the investigator's assessment. Information related to the treatment, including medication, disease condition, expenses, etc. will be periodically collected. Follow-up at 2-month intervals will be periodically performed to continually collect information about the disease progression, subsequent treatment and survival until death or completion of the study.

Recruited patients will fill out questionnaires about quality of life before initiation of treatment, at Cycle 3 and completion of first-line treatment.

Inclusion Criteria:

1. The patient has histologically confirmed locally-advanced or recurrent and/or metastatic gastric or esophagogastric junction adenocarcinoma, has missed the opportunity of surgical excision, making curative therapy impossible.
2. The informed consent form is signed.
3. A specimen of tumor tissue (puncture biopsy or surgical specimen) is available.
4. ECOG performance status is 0, 1 or 2.
5. The patient's general conditions and functions of important organs allow generalized chemotherapy according to the investigator's judgment
6. The patient is aged≥18

Exclusion Criteria:

1. The patient is known to be allergic to any study drug.
2. The patient is recruited in other clinical study or is planned to participate into other clinical study.
3. The patient has previously accepted chemotherapy against advanced or metastatic diseases (the patient may be recruited if the previous adjuvant therapy/neoadjuvant therapy was completed more than 6 months before inclusion).

patients with advanced gastric cancer