The study focuses on patients with locally advanced gastric adenocarcinoma (cT3N+M0 and cT4aN+/-M0), assessing the feasibility, surgical safety, and oncological benefit of prophylactic HIPEC treatment following laparoscopic D2 radical surgery.

Patients meeting the inclusion criteria will undergo laparoscopic D2 radical surgery. Before closing the abdomen during surgery, heat perfusion tubes are inserted, typically placing four tubes in a cross arrangement. Two drainage tubes at the pelvic floor exit through the upper abdomen, and two drainage tubes at the hepatorenal and splenorenal recesses exit through the lower abdomen, thus completing the tube placement.

Within 48 hours postoperative, the first infusion was performed with 3000-4000 ml of saline and 50 mg/m2 cisplatin at 43°C, with an infusion rate of 600 ml/min for a duration of 2 hours. During treatment, close attention is given to the patient's heart rate, blood pressure, oxygenation, and other vital signs. A total of 2 HIPEC treatments were conducted, each 48 hours apart. Systemic chemotherapy is initiated 3-4 weeks postoperative for 6-8 cycles using SOX: intravenous injection of oxaliplatin (130 mg/m2) on the first day and oral administration of tegafur (40-60 mg twice daily, with doses adjusted for body surface area: <1.25 m2, 40 mg; 1.25m2 ≤ body surface area ≤ 1.5m2, 50mg; body surface area >1.5m2, 60 mg bid) from day 1 to 14.

HIPEC is not performed postoperative. Systemic chemotherapy is initiated 3-4 weeks postoperative for 6-8 cycles using SOX: intravenous injection of oxaliplatin (130 mg/m2) on the first day and oral administration of tegafur (40-60 mg twice daily, with doses adjusted for body surface area: <1.25 m2, 40 mg; 1.25m2 ≤ body surface area ≤ 1.5m2, 50mg; body surface area >1.5m2, 60 mg bid) from day 1 to 14.

Inclusion Criteria:

1. Age >18 and ≤70 years;
2. Male or nonpregnant female;
3. Gastric adenocarcinoma cT3N+M0 and cT4aN+/-M0 (according to the 8th edition of the AJCC TNM staging system);
4. No distant metastasis, suitable for D2 lymph node dissection;
5. ECOG (Eastern Cooperative Oncology Group) performance status of 0-2;
6. No prior cytotoxic chemotherapy, radiotherapy, or immunotherapy;
7. Written informed consent given before any study-related procedures;

Exclusion Criteria:

1. Other cancers within the past 5 years;
2. Distant metastasis (M1) found during surgery;
3. ASA (American Society of Anesthesiologists) classification ≥IV and/or ECOG performance status >2;
4. Severe liver, kidney, cardiac, pulmonary, or coagulation dysfunction, or severe underlying diseases that make the patient unable to tolerate surgery;
5. A history of severe mental illness;
6. History of taking steroid medications;
7. Receiving other chemotherapy, radiotherapy, or immunotherapy;
8. Lack of written informed consent;

There are plans to make individual participant data (IPD) available to other researchers. Includes only basic information such as name and gender.