The esophagogastric junction (EGJ) is a very short anatomical section of the junction between the distal esophagus and the proximal cardia of the stomach. To date, there is still some controversy between Eastern and Western scholars on how to define this region. Japanese scholars consider the EGJ to be the end of the longitudinal fenestra-like vessels in the lower esophagus, while European and American scholars consider it to be the proximal edge of the gastric mucosal folds. Adenocarcinoma of the esophagogastric junction (AEG) is an adenocarcinoma that spans the EGJ region. While the incidence of gastric cancer has declined globally in the last 30 years, the incidence of AEG has been on the rise. In the United States, data from the Surveillance, Epidemiology, and End Results (SEER) project, sponsored by the National Cancer Institute, showed that the incidence of esophageal adenocarcinoma increased 240% over 20 years and pancreatic adenocarcinoma increased 50% among Caucasian men between 1974 and 1994. The most recent statistics from the project show that the incidence of AEG has increased nearly 2.5-fold in the last 35 years, with a stable incidence of about 2/100,000. In East Asia, a region with a high incidence of gastric cancer, the Japanese Cancer Surveillance Study Group showed that the proportion of AEG in all gastric adenocarcinomas increased from 2.3% in the early 1960s to 10% in 2000. The Asan Medical Center in Seoul, Korea, reported that the proportion of AEG in upper gastrointestinal tumors did not change significantly between 1992 and 2006. In China, statistics from a single center at West China Hospital of Sichuan University show that the proportion of AEG in all gastric adenocarcinomas has increased from 22.3% in the early 1990s to 35.7% at present. With the increase in incidence, more and more scholars have started to pay attention to this malignant tumor in this particular anatomical site. Clinically, there are two main staging methods for AEG: Nishi staging and Siewert staging. The former was proposed by Japanese scholar Mitsumasa Nishi as early as 1973, also known as the Japanese typing, and is based on the relationship between the center of the tumor and the EGJ, with five types, including E, EG, E=G, GE, and G. The main drawback of this typing is that it uniformly typed all pathological types of malignant tumors in the region, without distinguishing between adenocarcinoma and squamous carcinoma, and its scope is limited to It does not distinguish between adenocarcinoma and squamous carcinoma and is limited to within 2 cm above and below the EGJ. Therefore, it has less influence internationally, except for domestic use in Japan. The latter was proposed by Joerg Ruediger Siewert in 1987, and mainly includes adenocarcinoma with a tumor center within 5 cm above and below the EGJ, and is divided into three types. This typing is now widely adopted internationally and accepted by the academic community. As the incidence of the three types of AEG differs between Eastern and Western countries, the surgical team also differs. In the West, the incidence of the three types of AEG is essentially the same and surgery is often performed by upper gastrointestinal or thoracic surgeons, whereas in East Asia, since the vast majority of AEGs are Siewert types II and III, surgery is often performed by abdominal or gastrointestinal surgeons. Current controversies in the surgical treatment of AEG focus on the following points: the extent of lymph node dissection and the need for combined splenectomy; the choice of surgical access and approach; the extent of esophageal and gastric resection; and the use of minimally invasive techniques. In this paper, we discuss the current controversies of surgical treatment of AEG in the light of the literature. 1. Characteristics of lymph node metastasis and the scope of lymph node dissection With regard to the scope of lymph node dissection in AEG surgery, it is the consensus of most scholars that regional lymph node dissection should be performed according to the lymph node metastasis characteristics of different staging of AEG. Therefore, a large number of retrospective studies have been conducted to analyze the characteristics of lymph node metastasis in AEG by scholars from East and West. The results showed that (1) the incidence of abdominal lymph node metastasis was Siewert type III > Siewert type II > Siewert type I. Siewert type III had the highest incidence of intra-abdominal lymph node metastasis, while Siewert type II abdominal lymph node metastasis was mainly concentrated around the cardia, the large and small curvature of the stomach, the left gastric vessel to the peri-abdominal trunk, and around the splenic artery. A recent systematic evaluation including 17 retrospective studies also showed that the metastasis rates of Siewert type II AEG No. 1, 2 and 3 lymph nodes ranged from 13.7% to 72.7%, while the metastasis rates of No. 7, 9 and 11 lymph nodes ranged from 0 to 45.5%, which were significantly higher than the metastasis rates of other groups of lymph nodes in the abdominal cavity, while the metastasis rates of Siewert type I lymph nodes were mainly around the cardia, gastric lesser curvature and around the left gastric artery. Siewert et al. reported that the incidence of mediastinal lymph node metastasis in 1602 cases of AEG was 65%, 12% and 6% for Siewert type I, II and III, respectively. Another multicenter retrospective analysis from Italy also showed that the metastasis rate of Siewert type I, II and III mediastinal lymph nodes in progressive AEG (pT2-4) was 46.2%, 29.5% and 9.3%, respectively. The main factor affecting mediastinal lymph node metastasis is the length of the tumor invasion into the esophagus, and the longer the tumor involvement into the esophagus, the higher the incidence of mediastinal lymph node metastasis. The multifactorial analysis showed that the distance from the proximal end of the tumor to the EGJ was the only factor influencing mediastinal lymph node metastasis; (3) the metastasis rates of upper, middle and lower mediastinal lymph nodes in different strains of AEG varied greatly among different studies, especially in Siewert type II AEG. (4) Siewert type II and III AEG are associated with a higher incidence of metastasis in the parietal aortic lymph nodes. Another retrospective study from Japan also found that the incidence of metastasis in Siewert II and III No.16 lymph nodes could reach 12.2% and 20.7%, respectively. Based on the above characteristics, lymph node dissection in AEG should follow the following principles: (1) Siewert type I should follow the lymph node dissection for lower and middle esophageal cancer, including mediastinal and abdominal lymph nodes, while the abdominal dissection should include the lymph nodes around the cardia, the lesser curvature of the stomach and the left gastric artery; (2) Siewert types II and III should strictly follow the principles of lymph node dissection for radical gastric cancer to perform abdominal (2) Siewert II and III types should have abdominal lymph node dissection and lymph node dissection around the esophageal foramen in strict accordance with the principles of lymph node dissection for radical gastric cancer, and whether to perform lymph node dissection in the middle and lower mediastinum according to the extent of tumor invasion of the esophagus. No.110 and No.112 lymph nodes, it is recommended to sweep the perisylvian and lower mediastinal lymph nodes together; (3) although metastasis to the lymph nodes adjacent to the abdominal aorta is already a distant metastasis and is not an indication for radical surgery. However, in the latest Japanese Guidelines for the Treatment of Gastric Cancer, the resolution of seven clinical issues suggests that a few lymph nodes limited to No. 16a2 and No. 16b1 are enlarged without other non-curative factors, and that a combination of treatment including expanded surgical debulking is feasible. Therefore, Siewert types II and III can also be treated with a combination of surgical procedures with reference to the above principles. Goto et al. used total gastrectomy combined with splenectomy (D2 lymph node dissection) in 42 cases of Siewert II AEG, and the highest rate of postoperative pancreatic-related complications was 28.5%, with an overall 5-year survival rate of 57.7%. The overall 5-year survival rate was 57.7%, while the incidence of No.10 and No.11d lymph node metastases was only 4.8% and survival was <5 years. The incidence of No.10 lymph node metastasis in AEG was also reported to be <10% in most other papers. Western scholars also believe that splenic hilar lymph node dissection is not recommended, and splenectomy or combined pancreatic tail resection is only considered in the case of direct tumor invasion, considering the high postoperative complication rate and morbidity and mortality. The main purpose of the Japanese JCOG0110 clinical study was to evaluate the value of combined total gastric splenectomy for upper gastric cancer, and the results of this study will also provide new evidence-based evidence on the significance of splenectomy. The author's experience is that it is technically safe and feasible to perform lymph node dissection in No.10 and No.11d while preserving the spleen, and there is no need to pay the cost of splenectomy to complete lymph node dissection in this area. At present, the surgical approach of AEG mainly includes transthoracic approach and transabdominal approach, the former includes left thoracoabdominal incision, left thoracoabdominal incision, right thoracoabdominal incision and Ivor-Lewis incision. The former includes left thoracoabdominal, left thoracoabdominal, right thoracoabdominal (Ivor-Lewis) and left thoracoabdominal, while the latter mainly refers to the transabdominal transhiatal approach.) It is the goal of all surgeons to choose the appropriate surgical approach to achieve the perfect harmony between lymph node dissection and surgical safety. The results of two phase III clinical studies from the Netherlands and Japan provide a good evidence-based basis for the choice of surgical approach. In the Dutch study, patients with Siewert type I and II AEG were randomized to a postero-lateral transthoracic resection group and a transabdominal esophageal fissure resection group. The former group cleared lymph nodes around the thoracic duct, odd vein, ipsilateral pleura, and esophagus, as well as lymph nodes around the cardia, lesser curvature, left gastric artery, common hepatic artery, celiac trunk, and splenic artery, while the latter group cleared mediastinal lymph nodes below the level of the inferior pulmonary vein and lymph nodes in the abdominal cavity, but not routinely around the celiac trunk. Postoperative pulmonary complications were significantly higher in the transthoracic resection group, and the duration of postoperative mechanical ventilation, ICU stay, and total hospital stay were significantly longer, but there was no difference in the incidence of postoperative anastomotic leak or hospital mortality between the two groups. Follow-up results showed no statistically significant difference in 5-year survival between the two groups (34% vs. 36%, P=0.71), but subgroup analysis suggested a higher 5-year survival rate in the transthoracic resection group than in the transabdominal esophageal resection group for Siewert type I AEG patients (51% vs. 37%, P=0.33), and although the difference was not statistically significant, the study still noted that A transthoracic approach is recommended for Siewert type I AEG patients to achieve better survival rates. The Japanese JCOG9502 clinical study randomized Siewert type II and III AEG into a combined left-sided thoracoabdominal incision group and a transabdominal esophageal fissure group and showed a longer operative time, a higher transfusion rate, a higher complication rate in the combined left-sided thoracoabdominal incision group (49% vs. 34%, P=0.06), and 3 in-hospital deaths, while the difference in 5-year and 10-year survival rates between the two groups There was no statistically significant difference in 5- and 10-year survival rates between the two groups. Therefore, a transabdominal esophageal fissure approach is recommended for patients with Siewert II and III AEG. A meta-analysis comparing transthoracic and non-transthoracic approaches for AEG, which included five randomized controlled studies and seven non-randomized controlled studies, showed no differences in surgical complication rates, in-hospital mortality rates, and 5-year survival rates, nor in operative time, blood transfusions, secondary surgery rates, or number of lymph nodes removed, except for a longer hospital stay in the transthoracic approach group. Although the results of this Meta-analysis did not show a difference between the two surgical approaches, the authors believe that the final conclusions should be interpreted with caution due to the quality of the included studies. Currently, most scholars advocate a transthoracic approach with lymph node dissection of the mediastinum and abdominal cavity for Siewert I AEG, while national scholars also point out that when choosing a left or right transthoracic incision, one should still take into account the dissection of the upper mediastinal lymph nodes and the high off-end esophagus to ensure a negative upper margin, and therefore recommend the Ivor-Lewis approach. For Siewert types II and III, the preferred procedure is the transabdominal esophageal fissure approach, and intra-abdominal lymph nodes should be the focus of surgical debulking. The scope of esophageal and gastric resection for AEG is less controversial for Siewert I and III. For Siewert I AEG, subtotal esophageal resection plus proximal gastrectomy should be performed, while for Siwert III AEG, total gastrectomy is recommended according to the Japanese Guidelines for Gastric Cancer. However, there is still no conclusion on whether to perform proximal gastrectomy or total gastrectomy for Siewert type II and the extent of esophageal resection. The root cause of the debate is the incidence of lymph node metastasis in the greater curvature of Siwert type II AEG and in the superior and inferior pylorus, as well as the distance of tumor invasion into the esophagus, and the impact of both surgical approaches on postoperative quality of life. found that the incidence of lymph node metastasis in the greater curvilinear and supra- and inferior pyloric regions was <2.2% when the tumor was distal to the dentate line ≤30 mm, but reached 20.0% when the tumor was distal to the dentate line >50 mm. Therefore, it is recommended that the extent of gastric resection can be determined by the distance from the distal end of the tumor to the dentate line, and proximal gastrectomy can be performed when the distal end of the tumor is ≤30 mm from the dentate line, while total gastrectomy is recommended when it is >50 mm. Since AEG is characterized by metastasis along the submucosal lymphatic network, adequate esophageal resection should be performed to ensure safe anastomosis in patients with esophageal infiltration, and intraoperative cryopathological examination should be routinely performed. A recent systematic evaluation study included 10 clinical studies comparing esophagectomy and gastrectomy and showed that none of the surgical approaches demonstrated an advantage in oncologic evaluation, except that patients had a higher quality of life after gastrectomy. In terms of current trends, most scholars still recommend total gastrectomy for Siewert type II AEG. With the increasing use of multimodality therapy (MMT) for Siewert II AEG in recent years, neoadjuvant radiotherapy is likely to change the original surgical strategy and approach for tumor volume reduction and stage reduction. A 2015 retrospective study from the United States found that patients who underwent MMT were significantly more likely than those who underwent total gastrectomy (42.9% vs. 29.6%, P<0.001), with the result that overall survival was higher for the former than for the latter (26 months vs. 21 months, P=0.025). 4. Use of minimally invasive techniques As endoscopic screening continues to spread, the diagnosis rate of early AEG has also increased. As a result, minimally invasive techniques, including endoscopy and lumpectomy, have also been widely used. In terms of endoscopic treatment, a meta-analysis showed that for early AEG with ESD, the whole resection rate was 98.6%, the complete resection rate was 87.0%, and the incidence of postoperative stenosis was 6.9%. Among the 269 curative resection patients, no local recurrence or distant metastasis was observed in 1 case, while 3 cases of local recurrence and 2 cases of distant metastasis were observed among 90 non-curative resection patients. The results suggest that ESD is a feasible method for early AEG treatment, and its whole resection and complete resection rates are in the acceptable range. However, for endoscopic treatment, there are still two major issues: first, whether the evaluation of endoscopic treatment criteria and curative resection should follow the criteria for esophageal cancer or gastric cancer; second, because of the special location of EGJ, the operation is difficult and some serious complications may occur when performed in inexperienced endoscopic centers. The author suggests that endoscopic resection for early-stage AEG should still be performed with adequate evaluation to clarify the tumor pathological type and depth of infiltration as well as the metastasis of surrounding lymph nodes, and strictly follow the indications for endoscopic treatment. As for laparoscopic surgery, AEG involves both abdominal and thoracic areas. Therefore, a variety of surgical techniques and modalities are used, including laparoscopic surgery alone or thoracoscopic surgery, as well as laparoscopic combined with thoracoscopic surgery. Early systematic evaluations showed that a total of 46 studies involving minimally invasive surgery for gastrectomy and esophagectomy, including 3 randomized controlled studies, were performed between 1997 and 2007, with laparoscopic surgery involving esophagectomy being predominantly reported in Western studies. The results showed that minimally invasive surgery brought the advantages of less bleeding, faster recovery of postoperative gastrointestinal function, and fewer days of hospitalization, and therefore the procedure was considered feasible in gastric and esophageal resection, but the study lacked follow-up data and the quality of the study data was not optimal. In recent years, a number of randomized controlled studies have been conducted in Western countries on the implementation of lumpectomy for AEG. The results of a single-center prospective study from the United Kingdom comparing right thoracoabdominal two-incision open surgery with total laparoscopy combined with thoracoscopic surgery for middle and distal esophageal and EGJ cancer showed that the differences in the incidence of postoperative anastomotic leak, R0 resection rate, and number of lymph nodes cleared between the two surgical approaches were not statistically significant However, the bleeding volume was significantly lower in the all-laparoscopic group (300 mL vs. 400 mL, P=0.021), which also demonstrates the benefits of minimally invasive surgery achieved by experienced surgeons performing all-laparoscopic surgery, but the study remains small in enrollment and is a single-center study that is not generalizable enough to be replicated. In addition, another multicenter phase III trial comparing open versus laparoscopic-assisted mid- and distal esophageal resection is underway, using laparoscopic-assisted gastric free and open esophageal resection for mid- to lower 1/3 esophageal cancer, compared with the conventional Ivor-Lewis approach, with the primary study endpoint being the 30-d postoperative complication rate and secondary endpoints including 30-d operative mortality, 30-d pulmonary complication rate, and 30-d lung complication rate. d pulmonary complication rate, disease-free survival, and overall survival. The results of this study are expected to provide a higher level of evidence-based medical evidence to further clarify the advantages and disadvantages of minimally invasive surgery in AEG. 5. Conclusion Due to the special biological characteristics of AEG, a combination of standardized and individualized surgical access, lymph node dissection and gastrointestinal tract resection and reconstruction is very necessary and is the direction of research for more clinical trials in the future. Meanwhile, the minimally invasive treatment for early stage AEG patients and the integrated treatment including traditional surgery and radiotherapy for progressive and advanced AEG will be a common problem for physicians from related disciplines such as gastrointestinal surgery, thoracic surgery, gastroenterology, medical oncology and radiotherapy in the future. In the future, the diagnosis and treatment of AEG will need to be accomplished through a multidisciplinary collaboration model.