Is lymph node dissection for neuroendocrine carcinoma of the stomach effective as it is for adenocarcinoma?

Background: We evaluated the significance of lymph node dissection for gastric neuroendocrine carcinoma (NEC) by calculating the therapeutic value index for each station.
Methods: This study included 2164 advanced gastric cancer patients (common-type [Common-GC], n = 2125; and gastric NEC [NEC-GC], n = 39). Clinicopathological data were collected, and survival, type of recurrence, and the index for each type of gastrectomy were determined.
Results: NEC-GC was characterized by an older population (P = 0.009), upper tumor location (P = 0.021), frequent venous invasion (P < 0.001), and less neural invasion (P = 0.043). NEC-GC tended to be more frequent in men (P = 0.152), and to be associated with total gastrectomy (P = 0.177) and M1 cases (P = 0.167). The five-year overall survival rates of the Common-GC and NEC-GC groups were 73.8% (95% confidence interval: 71.8-75.6) and 54.7% (37.5-68.9), respectively (P = 0.016). Both groups showed similar index values in each station. Regarding the index of the peri-gastric nodal station (D1 station)/stations away from the stomach (D2 station), although the index of the D1 station was similar in the two groups (41.3 and 43.1), the index of the D2 station in the NEC-GC group was approximately half that of the Common-GC group (10.0 and 5.3). The total recurrence rates of the two groups were similar (P = 0.871). However, the rates of hematogenous and lymphatic recurrence tended to be higher in the NEC-GC group (P = 0.132 and P = 0.152).
Conclusions: The therapeutic efficacy of the D1 station was similar in Common-GC and NEC-GC but that of the D2 station was worse in NEC-GC. Gastrectomy with D2 dissection would be less effective for NEC-GC.
Competing Interests: Declaration of competing interest Dr. Yamagata has nothing to disclose. Dr. Yoshikawa reports personal fees from ONO, personal fees from MSD, personal fees from Lilly, personal fees from TAIHO, personal fees from Chugai, personal fees from Nihon Kayaku, personal fees from BMS, personal fees from Daiichi Sankyo, personal fees from TERUMO, personal fees from Johnson and Johnson, personal fees from Pfizer, personal fees from Olympus, personal fees from Yakult, personal fees from Eizai, personal fees from Kyowa, personal fees from Covidien, outside the submitted work;. Dr. Ishizu has nothing to disclose. Dr. Kamiya has nothing to disclose. Dr. Wada has nothing to disclose. Dr. Hayashi has nothing to disclose. Dr. Otsuki has nothing to disclose. Dr. Katai has nothing to disclose.
(Copyright © 2021 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.)