Efficacy of nodal dissection for locoregional gastric neuroendocrine carcinoma: a multicenter retrospective observational study.

Background: Gastric neuroendocrine carcinoma (NEC) is a rare and aggressive malignancy for which no standard treatment has been established for locoregional disease. This multicenter retrospective study aimed to evaluate the prognostic relevance and therapeutic efficacy of lymph node dissection in this setting.

Methods: A total of 118 patients with gastric NEC or mixed adenoneuroendocrine carcinoma (MANEC) who underwent gastrectomy with lymph node dissection were analyzed. Survival outcomes, clinicopathological factors, and the therapeutic value index of each lymph node station were assessed. Lymph node involvement was classified using both the pathological N category and the extent of nodal involvement based on the dissection area (pND).

Results: The 5-year overall survival and 3-year recurrence-free survival rates were 56.7% and 63.4%, respectively. Prognostic stratification using pND provided clearer separation than using the conventional pN category. Multivariate analysis identified older age, female sex, and pND2 (metastasis to D2 area nodes) as independent unfavorable prognostic factors. The therapeutic value index for lymph nodes in the D1 area was high (35.0, based on 5-year overall survival), whereas the index for D2 nodes was markedly lower (6.8). Notably, these indices remained consistent across histological subtypes, showing similar values between NEC and MANEC. Postoperative chemotherapy and surgical complications did not significantly affect survival outcomes.

Conclusions: Perigastric (D1) lymph node dissection appears to provide meaningful survival benefit in locoregional gastric NEC, whereas the additional value of D2 dissection is limited. These findings support consideration of a more selective surgical approach, though further validation is needed.