Lymph node metastatic patterns of gastric carcinoma with a combination of adenocarcinoma and neuroendocrine carcinoma components

BACKGROUND Gastric mixed-adenoneuroendocrine carcinoma (G-MANEC) is a subtype of gastric cancer. Building upon prior research findings, we propose that tumours containing both neuroendocrine carcinoma (NEC) and adenocarcinoma (AC) components, with each component ranging from 1% to 99% of the tumour, be classified as a distinct entity. We hereby term this adenoneuroendocrine mixed gastric cancer (G-ANEC). Research on lymph node (LN) involvement in G-MANEC has focused mainly on metastasis status, with limited studies on metastatic composition. AIM To investigate the LN metastasis patterns of G-ANEC, the clinicopathological features associated with these metastasis patterns, and to explore adjuvant chemotherapy regimens for G-ANEC. METHODS We analyzed 68 G-ANEC cases treated with radical surgery and confirmed LN metastasis at Peking University Cancer Hospital between August 2012 and June 2022. Utilizing chi(2) tests in IBM statistical product and service solutions statistics and R software. RESULTS We identified three distinct LN metastasis patterns in G-ANEC that were significantly associated with the NEC proportion, tumour invasion depth, Lauren classification, and tumour location (P values: 0.008, 0.015, 0.01, and 0.004, respectively). When the SOX/XELOX regimen was applied for adjuvant chemotherapy, patients with LN metastasis comprising only AC exhibited better overall survival (OS) (94.25 +/- 11.07 months vs 54.36 +/- 11.36 months) than did those with NEC. When LN metastasis components contained NEC, there was a trend towards improved OS (64 +/- 10.77 months vs 54.35 +/- 11.36 months) and disease-free survival (71.28 +/- 9.92 months vs 66.28 +/- 11.93 months) in patients treated with the etoposide and cisplatin compared to those receiving the SOX/XELOX regimen. CONCLUSION We found a significant correlation between the NEC percentage, tumour invasion depth, Lauren classification, and tumour location and LN metastasis patterns in G-ANEC. For G-ANEC, a lower proportion of NEC or AC in the primary lesion does not preclude the possibility of these components metastasizing to the LNs. Different adjuvant chemotherapy regimens should be administered on the basis of the varying components of LN metastasis in patients with G-ANEC.