The purpose of this study is to explore the clinical application value of Double-Stapling End-to-End Gastroduodenostomy Billroth-I Anastomosis in Laparoscopy-Assisted Surgery for Locally Advanced Distal Gastric Cancers.

As one of the core contents of gastric cancer surgery, the choice of digestive tract reconstruction method has always been the focus of clinical research in gastric cancer surgery. There are many alternative methods of digestive tract reconstruction at present, but there is no absolute superiority among various reconstruction methods. According to the individual characteristics of patients, the selection of appropriate digestive tract reconstruction methods should be an important direction in the future research field of digestive tract reconstruction.

There are many methods of digestive tract reconstruction in distal gastrectomy, including Billroth-I anastomosis, Billroth-II anastomosis and Roux-en-Y anastomosis. However, the standard method of reconstruction after distal subtotal gastrectomy does not reach a consensus. According to Korean Practice Guideline for Gastric Cancer 2018, gastroduodenostomy and gastrojejunal anastomosis are recommended after distal subtotal gastrectomy for middle-low gastric cancer, but the priority of different surgical procedures is not clarified. The conclusion is that there is no significant difference between the Billroth-I, Billroth-II and Roux-en-Y in postoperative quality of life, nutritional status and long-term prognosis of patients. Roux-en-Y anastomosis has a lower incidence of bile reflux, but a higher incidence of delayed gastric emptying compared with Billroth-I and Billroth-II. Similarly, the Japanese gastric cancer treatment guidelines in 2018 did not specify the priority of reconstruction methods after distal gastrectomy. In China, the 2022 CSCO guidelines for the diagnosis and treatment of gastric cancer also did not specify the priority of reconstruction methods, pointing out that alternative reconstruction methods include Billroth-I, Billroth-II combine with Braun anastomosis, Roux-en-Y anastomosis, and jejunal interposition. However, the number of alternative methods indicates that no ideal reconstruction method has absolute advantages. Therefore, in clinical practice, the specific choice of digestive tract reconstruction method often needs to be determined by considering many factors, including the location of the primary tumor, tumor stage, lymph node condition, anatomical variation and patient's economic situation, etc., which are important factors affecting the choice of digestive tract reconstruction method.

With the development of laparoscopic technique in recent years, totally laparoscopic digestive tract reconstruction has become a hot spot in the surgical treatment of gastric cancer. Laparoscopic digestive tract reconstruction has smaller incision and less trauma, which is a higher-level laparoscopic surgery pursued by surgeons. However, for patients undergoing radical gastrectomy for distal gastric cancer, totally laparoscopic distal gastroduodenal anastomosis is technically difficult. Delta anastomosis was proposed by Professor Kannaya in Japan in 2002. In this technique, the functional end to end anastomosis of the posterior wall of the remnant gastroduodenal was completed by using endoscopic linear staplers under totally laparoscopy, and the suture nails inside the anastomosis were triangular. It is a widely used functional end to end anastomosis of remnant gastroduodenum after distal gastrectomy under totally laparoscopic surgery. However, because of the operation in the duodenum and stomach from broken should meet the requirements of R0 resection of tumor, proper anastomotic tension, and blood supply of free longer duodenal stump, its restrictive factors, poor controllability, security is still not widely recognized, it can only be carried out in centers with rich experience in laparoscopic surgery, and it is more suitable for early cases of gastric Antrum.

In 2016, Professor Changming Huang found that modified Delta anastomosis is safe and feasible in early gastric cancer, but caution is still needed for locally advanced gastric cancer, its incidence of postoperative complications and anastomotic leakage was significantly higher than that of laparoscopic-assisted Billroth-I anastomosis.

In 1995, Oka et al. reported the use of circular stapler for functional end to end anastomosis of remnant gastroduodenum in open distal gastric cancer radical resection. In 2004, they reported the results of 221 cases, showing that this anastomosis was clinically safe and reliable. In 2007, Yang et al. in Korea confirmed that functional end to end anastomosis was safe and feasible in 933 cases of distal gastric cancer, with similar short-term outcomes compared with Billroth-II anastomosis. However, the clinical staging of gastric cancer patients in Japan and Korea is mainly early stage, but in China, the clinical staging of gastric cancer patients is mostly advanced stage.

In conclusion, traditional Billroth-I end-to-side anastomosis and Delta anastomosis require an additional residual gastric tissue of at least 3cm. In addition, the safe margin of the broken end of advanced gastric cancer requires a distance of at least 3-5 cm from the tumor, which often leads to higher anastomotic tension and significantly increases the risk of anastomotic leakage. Therefore, we propose a new technique for gastrointestinal reconstruction in laparoscopic distal radical gastrectomy in locally advanced gastric cancer: Double-Stapling End-to-End Gastroduodenostomy Billroth-I Anastomosis in Laparoscopy-Assisted Surgery. After previous practice, this anastomotic method can not only ensure a safe surgical margin, but also retain more residual stomach, so as to effectively solve the problem of anastomotic tension. It is a safe, simple, physiological and economic anastomotic method.

Inclusion Criteria:

• Age from 18 to years (including 18 and 85years old)
• Pathological diagnosis of primary focus is gastric adenocarcinoma made by endoscopic biopsy (papillary, tubular, mucinous, signet ring cell, poorly differentiated)
• cT1-4a, N+/-, M0 at preoperative evaluation
• No peritoneal metastasis or other distant metastases of gastric carcinoma (affirmed by laparoscopic surgery and related imaging examinations)
• Expected curative resection through laparoscopic distal gastrectomy with D2 lymphadenectomy (include multiple primary lower gastric adenocarcinoma)
• Performance status of 0 or 1 on Eastern Cooperative Oncology Group scale (ECOG)
• Preoperative American Society of Anesthesiology score (ASA) classⅠ, Ⅱ or Ⅲ
• Major organs are functioning normally:

blood routine test (No blood transfusions in the last 14 days): HB≥90g/L, ANC≥1.5×109/L, PLT≥80×109/L blood biochemical examination: BIL<1.5× upper limit of normal (ULN), ALT and AST<2.5×ULN, Crea≤1×ULN.

- The subject is willing to participate in this clinical trail

Exclusion Criteria:

• History of previous upper abdominal surgery (include ESD/EMR, except laparoscopic cholecystectomy)
• History of acute pancreatitis
• Regional fusion of enlarged lymph nodes by preoperative imaging (maximum diameter >3cm)
• History of other malignant disease within past five years
• History of unstable angina, myocardial infarction, cerebral infraction, or cerebral hemorrhage within past six months
• History of continuous systematic corticosteroids therapy within past one month
• Requirement of simultaneous surgery for other disease
• Emergency surgery due to complication (bleeding, or perforation) caused by gastric cancer
• FEV1<50% of predicted values by pulmonary function test
• Women during pregnancy or breast-feeding
• Severe mental disorder
• Participating in other clinical studies simultaneously
• Refusing to sign the informed consent for the study
• Peritoneal implant or other distant metastases by intraoperative exploration
• Unresectable due to tumor reasons by intraoperative exploration
• Distal gastric cancer surgery cannot be performed after intraoperative exploration
• Duodenal bulb has been invaded by tumor or gastroduodenostomy cannot be performed due to additional surgical resection cause by positive intraoperative frozen margin

All eligible patients enrolled in this study would undergo double-stapling end-to-end gastroduodenostomy Billroth-I anastomosis in laparoscopy-assisted surgery