[Current status and research progress of lymph node dissection in advanced upper gastric cancer]

In recent years, the incidence of gastric cancer has shown a decreasing trend. However, the incidence of advanced upper gastric cancer in China is steadily increasing. Nowadays, surgery is the only way to cure advanced gastric cancer, and lymph node dissection is the key of operation. Since lymph node metastasis is the main metastatic route of gastric cancer, it is critical for surgeons to be aware of this when performing lymph node dissection during operation. At present, the only possible cure for advanced gastric cancer is surgery. The key to a successful operation is to completely dissect the lymph nodes, which has a direct influence on the patient's postoperative survival rate. The lymph node metastasis rate is one of the important predictors of postoperative prognosis in patients with gastric cancer, which is related to the tumor size and especially the depth of invasion. Generally speaking, the deeper the tumor depth and/or the larger the tumor diameter, the relatively higher the lymph node metastasis rate will be. The lymph node metastasis rate determines the extent of lymph node dissection in advanced upper gastric cancer. As D2 lymphadenectomy can bring about a more thorough clearance for the perigastric metastatic lymph nodes and can improve the survival rate of patients with advanced gastric cancer, it has become the standard surgery for advanced gastric cancer. However, during treating advanced upper gastric cancer, since there are multiple and intricate ways for upper gastric cancer to metastasize through lymphatic route, there are still controversials on the necessity to perform mediastinal lymphadenectomy, para-aortic lymphadenectomy or dissection for lymph nodes around superior mesenteric vein remains controversial, as well as the necessity for splenectomy while doing splenic hilar lymphadenectomy or the necessity for distal gastric lymphadenectomy when the tumor diameter is less than 4 cm. In order to avoid postoperative pathological staging bias and to guide the further treatment after surgery, the number of dissected lymph nodes in advanced upper gastric cancer is currently required for no less than 15, but it is still controversial on the specific number of lymph node dissected that will improve the prognosis and prolong the survival time. In this paper, the current status and research progress of lymph node dissection in advanced upper gastric cancer are reviewed, in order to provide relevant bases and references for performing lymph node dissection in treating upper gastric cancer.