Adenocarcinoma of the esophagogastric junction (AEG) is an adenocarcinoma located in the junction region of the distal esophagus and proximal gastric cardia. In recent years, domestic and foreign studies have shown that the incidence of distal gastric cancer is gradually decreasing worldwide, but the incidence of AEG is increasing year by year worldwide, therefore, this disease is receiving more and more attention from scholars. However, due to the special anatomical location, no consensus has been reached regarding the surgical treatment of AEG. In the treatment of AEG, physicians focus on the following issues.
Staging and staging
There are two main approaches to staging AEG, the Japanese Society for Gastric Cancer staging and the Siewert staging.
In the Japanese Society of Gastric Cancer staging, the area 2 cm above and below the esophagogastric junction line is defined as the esophagogastric junction, and AEG is classified into 5 types according to the relationship between the center of the tumor and the junction line: type E (tumor mainly on the esophageal side), type EG (tumor on the esophageal side), type E = G (tumor across the esophagogastric junction), type GE (tumor on the gastric side), and type G (tumor mainly on the gastric side).
The Siewert typing classifies adenocarcinomas with a tumor centered within 5 cm above or below the esophagogastric junction line into 3 types: type I is located 1 cm to 5 cm above the junction line, which is adenocarcinoma of the lower esophagus; type II is located between 1 cm above and 2 cm below the junction line, which is carcinoma of the cardia; and type III is located 2 cm to 5 cm below the junction line, which is also called fundic carcinoma. The Siewert staging is widely accepted internationally because it provides greater guidance on surgical approach and lymph node dissection.
In the latest 8th edition of TNM staging, AEG tumors centered 2 cm below the esophagogastric junction line and invading the junction line are treated as esophageal cancer staging; tumors within 2 cm of the esophagogastric junction line and not invading the junction line, and tumors centered >5 cm from the junction line with or without invading the junction line (i.e., Siewart type III) are treated as gastric cancer staging
Selection of surgical approach and extent of resection
Clinically, the surgical approach for Siewert type I AEG consists of a transthoracic and a transabdominal approach, either open or open, with the transthoracic approach including left-sided, right-sided, and left-sided combined thoracoabdominal approaches, and the transabdominal approach usually using a transabdominal esophageal fissure approach. The advantages of the transthoracic approach are adequate surgical exposure, complete mediastinal lymph node dissection, and the ability to remove a long enough esophagus to ensure negative margins, but there are disadvantages such as pulmonary complications, celiac disease, and high rates of incisional infection.
After a long period of research and exploration in China and abroad, the surgical pathway and extent of resection for different staging of AEG can usually follow the following recommendations:
- Siewert I
- The transthoracic approach is preferred for Siewert I AEG, whereas the transabdominal approach is more suitable for patients of advanced age, poor cardiopulmonary reserve, and those who cannot tolerate transthoracic surgery.
- The extent of surgical resection for Siewert I AEG includes distal esophagectomy combined with proximal gastrectomy.
- The surgical approach for Siewert II and III AEG includes both a combined left-sided thoracoabdominal approach and a transabdominal approach, with the transabdominal approach being the most preferred option when the tumor infiltrates the esophagus by more than 3 cm and radical surgery is feasible. Siewert II and III progressive AEG are treated by total transabdominal gastrectomy and partial resection of the distal esophagus through the diaphragmatic foramen. Proximal gross gastrectomy is only indicated for stage T1 tumors and must preserve more than the distal 1/2 of the stomach.
On the extent of esophageal resection, it is generally accepted that the upper incisional margin should be 2 to 3 cm from the tumor margin for early-stage tumors and 4 to 5 cm from the tumor margin for progressive-stage tumors.
Minimally invasive endoscopic treatment
Minimally invasive endoscopic treatment mainly includes two types of endoscopic mucosal resection (EMR) and endoscopic mucosal dissection (ESD). The Japanese Guidelines for the Treatment of Gastric Cancer (3rd edition) recommend that EMR and ESD be considered for stage T1a AEG. endoscopic treatment is indicated for tumors that are moderately or highly differentiated, do not invade lymphatic vessels, are less than 3 cm in diameter, and are confined to the mucosa.
If the tumor is more than 2 cm in diameter and cannot be resected in a single pass by EMR, then a fractional resection method (EPMP) is required. However, EPMP is prone to residual lesions and recurrence, whereas ESD is a good solution, but ESD is technically demanding and usually requires additional surgical treatment if treatment is incomplete or if the tumor invades the submucosa. (Contributed by Wenbin Hou, Department of Gastrointestinal Oncology, The First Hospital of China Medical University)