Therapeutic Value of Lymph Node Dissection in Advanced Gastric Cancer with Macroscopic Duodenum Invasion: Is the Posterior Pancreatic Head Lymph Node Dissection Beneficial?

In advanced gastric cancer (AGC) with duodenum invasion, the posterior pancreatic lymph nodes are susceptible to metastasis because of their proximity to the duodenum. The therapeutic value of lymph node dissection in this area for AGC with macroscopic duodenum invasion remains unclear. Patients who had undergone curative gastrectomy for lower-third AGC from 1970 to 2004 at the Cancer Institute Hospital were recruited for this study. Clinicopathological data were collected retrospectively, and compared between cases of AGC with duodenum invasion (AGC-DI group) and AGC without duodenum invasion (AGC-nDI group). In the AGC-DI group, the therapeutic value of lymph node dissection was evaluated using a therapeutic index (multiplication of the frequency of metastasis to the station by the 5-year survival rate of patients with metastasis to that station). The AGC-DI group generally had tumors of higher pathological stage, which might account for the poorer 5-year survival rate compared with that of the AGC-nDI group (50.1% versus 68.5%; P = 0.0002). The incidence of lymph node metastasis was higher in the AGC-DI group than that in the AGC-nDI group, including nodes in the posterior pancreatic head (23.9% versus 7.0%, P < 0.0001). In the AGC-DI group, posterior pancreatic head lymph node dissection was of therapeutic value (4.19) equivalent to dissection of second-tier lymph nodes. The dissection of posterior pancreatic head lymph nodes might be effective in AGC with macroscopic duodenum invasion since this has therapeutic value equivalent to that of second-tier lymph node dissection and might improve patients' long-term outcomes.