Gastric cancer remains a major health problem in East Asia. In contrast, in the United States and Western Europe, the incidence of gastric cancer has declined but is often diagnosed at an advanced stage. Thus, the number of operations that a surgeon performs annually varies according to region, so it is not easy to define which type of gastric cancer surgery should be considered the global standard. Nevertheless, a consensus that D2 dissection is the most appropriate way to treat resectable advanced gastric cancer has been reached based on the results of long-term follow-up of the Dutch D1 versus D2 trial¹ and the Japan Clinical Oncology Group (JCOG) 9501 study,² which confirmed no survival benefit with more extensive lymphadenectomy.

Radical surgery for gastrointestinal cancer focused on en bloc removal of the primary tumor along with lymphovascular drainage by excising organ-specific mesenteries. This general concept is widely accepted in colorectal cancer surgery and is realized as total mesorectal excision (TME) or complete mesocolic excision (CME).^3,4 D2 gastrectomy entails systematic dissection of all the nodes along the celiac axis (CA) and its named branches as well as the perigastric nodes. Based on embryologic principles, D2 gastrectomy is essentially a realization of mesentery-based surgery despite the anatomic restrictions inherent to the mesogastrium.⁵

The basic technique of lymph node dissection is common for all gastrointestinal cancers. However, because of the high incidence of tumor deposits in the adipose tissue and significant tendency of developing peritoneal metastasis in gastric cancer, dissection without destroying the intact fascial package surrounding the fatty tissue where all nodes and tumor deposits are imbedded is of paramount importance.⁶ To perform a proper lymph node dissection of the stomach, an understanding of the unique anatomic structure of the mesogastrium is essential. The stomach has 2 mesenteries: the dorsal mesogastrium and the ventral mesogastrium. During the rotation of the intestinal system, the ventral mesogastrium becomes the lesser omentum and the dorsal mesogastrium becomes the greater omentum. The mesoduodenum and the transverse mesocolon are eventually overlaid by the greater omentum. The dorsal pancreas arises from the duodenal wall, grows into the mesoduodenum, and eventually extends into the dorsal mesogastrium. The anterior surface of the mesoduodenum is then overlaid by the proper transverse mesocolon and the greater omentum. These fetal events produce certain anatomic restrictions to conduct mesentery-based gastric cancer surgery. From the viewpoint of mesenteric structures, however, it is important to recognize that regional lymph node stations can be embedded in the dorsal or ventral mesogastrium, as shown in Figure 32-1A.

The simplified mesogastrium after restoration of embryonic concrescences is shown in Figure 32-1B. The dorsal mesogastrium can be divided into 3 sectors: the root, intermediate, and perigastric sectors. Station no. 9 surrounding the CA would be equivalent to the root sector of the whole gastric mesentery. The intermediate sector, which envelopes the pancreas, would include nodes along the left gastric artery (no. 7), common hepatic artery (no. 8), splenic hilum (no. 10), and splenic artery (no. 11). The perigastric sector would include nodes situated at the right (no. 1) and left cardia (no. 2) and lesser (no. 3a) and greater curvature (no. 4). The no. 6 infrapyloric station lies within the mesoduodenum beyond the boundary of the mesogastrium. The remaining few stations, that is, nos. 3b and 5, along the right gastric artery, and 12, along the proper hepatic artery, are originally included in the ventral mesogastrium.

The dissection of N2 nodes by “complete” mesogastric excision with central vascular ligation like CME is disturbed by the presence of the pancreas and some branches arising from the CA. Ligation of the CA in radical gastrectomy is anatomically possible since the blood supply to the liver is secured in most cases by the pancreatoduodenal arcades from the superior mesenteric artery. However, by preserving the gastroduodenal artery, even Appleby’s operation cannot realize complete mesogastric excision. Further, the division of the CA entails combined splenopancreatectomy even when the organs are not directly invaded. Instead, as shown in Figure 32-1C, D2 gastric cancer surgery should aim at systematic mesogastric excision, that is, en bloc excision of the mesogastrium while excluding the pancreas and its associated vessels.⁵ This concept is expected to aid the universalization of the operative strategy for gastric cancer, as is currently the case for TME and CME in colorectal cancer.