The number of metastasic lymph nodes in gastric cancer is one of the most important prognostic factors. Despite it importance, the extent of lymph node dissection during gastrectomy for gastric cancer is still debated, and different types of lymph node dissection are currently used worldwide.
The draining lymph node basins for the stomach have been meticulously divided into 16 stations by Japanese surgeons. Stations 1 to 6 are perigastric, and the remaining 10 are located adjacent to major vessels, behind the pancreas, and along the aorta.
D1 lymphadenectomy refers to a limited dissection of only the perigastric lymph nodes (stations 1 to 7). D1 lymphadenectomy is indicated for T1a tumors that do not meet the criteria for EMR (endoscopic mucosal resection)/ESD (endoscopic submucosal dissection), and for cT1bN0 tumors that are histologically distinct and 1.5 cm or smaller in diameter.
In the Japanese literature, a D1+ lymphadenectomy refers to a D1 lymphadenectomy plus stages 8a, 9, and 11p. D1 + lymphadenectomy is indicated for cT1N0 tumors other than the above.
D2 lymphadenectomy is an extended lymph node dissection, entailing removal of nodes along the hepatic, left gastric, celiac, and splenic arteries, as well as those in the splenic hilum (stations 1 to 12a). D2 lymphadenectomy is indicated for potentially curable T2-T4 tumors as well as cT1N+ tumors.
D3 dissection is a superextended lymphadenectomy including the removal of nodes within the porta hepatis and periaortic regions (stations 1 to 16)
Recent studies support the concept that if the D2 dissection can be performed with low operative mortality, similar to that of a D1 dissection (as is the case in high volume centers), survival will be positively affected. D2 dissection is preferred in patients with potentially curable gastric cancer.
Concerning D3 dissection, several studies concluded that the resection of the para-aortic nodes do not provide any significant survival benefit.
In conclusion, recent studies suggest that cancer-specific mortality rates are significantly lower in patients who undergo D2 lymphadenectomy rather than D1. By contrast, there is no evidence that a D3 (para-aortic lymphadenectomy) confers a survival benefit over D2 dissection, and it is associated with higher perioperative mortality.