The aim of this trial is to confirm the non-inferiority of Gasless laparoscopy-assisted distal D2 radical gastrectomy to the conventional laparoscopy-assisted distal D2 radical gastrectomy for the treatment of advanced gastric cancer patients (T2-4a, N0-3, M0).

The primary end point was operative time for Gasless laparoscopy-assisted distal D2 radical gastrectomy and conventional laparoscopy-assisted distal D2 radical gastrectomy. The secondary outcomes of interest were intraoperative vital signs; postoperative pain; and surgeon satisfaction for D2 radical gastrectomy.

Inclusion Criteria:

1. Age >18 and <75 years old;
2. The gastric primary lesion is diagnosed as gastric adenocarcinoma by endoscopic biopsy histopathologic techniques (papillary adenocarcinoma [pap], tubular adenocarcinoma [tub], mucinous adenocarcinoma [muc], signet ring cell carcinoma [sig], and poorly differentiated adenocarcinoma [por]);
3. Preoperative clinical staging of T2-4a, N0-3, M0 (see preoperative assessment program; tumor staging is in accordance with AJCC-7th TNM);
4. It is expected that R0 surgical results will be obtained by distal subtotal gastrectomy and D2 lymph node dissection (also applies to multiple primary tumors)
5. Preoperative ECOG status score of 0/1;
6. Preoperative ASA (American society of anesthesiology) class of I -III;
7. Patients signed informed consent.

Exclusion Criteria:

1. Pregnant or lactating women;
2. Serious mental illness;
3. History of abdominal surgery (except for laparoscopic cholecystectomy);
4. History of gastric surgery (including ESD/EMR for gastric cancer);
5. Preoperative imaging examination suggests regional integration enlargement of lymph nodes (maximum diameter ≥3 cm)
6. Other malignant disease history within five (5) years;
7. Patients who received or were recommended a new adjuvant therapy;
8. History of unstable angina or myocardial infarction within six (6) months;
9. History of cerebral infarction or cerebral hemorrhage within six (6) months;
10. History of sustained systemic corticosteroid therapy within one (1) month;
11. Patients requiring simultaneous surgical treatment of other diseases;
12. Gastric cancer complications (bleeding, perforation, obstruction) requiring emergency surgery;
13. Pulmonary function test with FEV1 <50% of the expected value.