To investigate the clinicopathological factors and clinical significance of (micro)metastasis in No.12b lymph node in patients with gastric antrum cancer.

This was a retrospective cohort study of data of 242 patients with gastric adenocarcinoma without distant metastasis, complete follow-up data, and no preoperative anti-tumor therapy or history of other malignancies. All study patients had undergone radical gastrectomy (at least D2 radical range) + No.12b lymph node dissection in the Department of Gastric Surgery of Liaoning Cancer Hospital from January 2007 to December 2012. Immunohistochemical staining with antibody CK8/18 was used to detect micrometastasis to lymph nodes. Patients with positive findings on hematoxylin and eosin stained specimens and/or CK8/18 positivity in No.12b lymph node were diagnosed as having No.12b (micro)metastasis and included in the No.12b positive group. All other patients were classified as 12b negative. We investigated the impact of No.12b (micro)metastasis by comparing the clinicopathological characteristics and recurrence free survival (RFS) of these two groups of patients and subjecting possible risk factors to statistical analysis.

Traditional hematoxylin-eosin staining showed that 15/242 patients were positive for No.12b lymph nodes and 227 were negative. A total of 241 negative No. 12b lymph nodes were detected. Immunohistochemical testing revealed that seven of these 241 No.12b lymph nodes (2.9%) were positive for micrometastasis. A further seven positive nodes were identified among the 227 nodes (3.1%) that had been evaluated as negative on hematoxylin–eosin-stained sections. Thus, 22 /242 patients' (9.1%) No.12b nodes were positive for micrometastases, the remaining 220 (90.9%) being negative. Factor analysis showed that No.12b lymph node (micro) metastasis is associated with more severe invasion of the gastric serosa (HR=3.873, 95%CI: 1.676-21.643, P=0.006), T3 stage (HR=1.615, 95%CI: 1.113-1.867, P=0.045), higher N stage (HR=1.768, 95%CI: 1.187-5.654, P=0.019), phase III of TNM stage (HR=2.129, 95%CI: 1.102-3.475, P=0.046), and lymph node metastasis in the No.1/No.8a/No.12a groups (HR=0.451, 95%CI: 0.121-0.552, P=0.035; HR=0.645, 95%CI:0.071-0.886, P=0.032; HR=1.512, 95%CI: 1.381-2.100, P=0.029, respectively). Survival analysis showed that the 5-year RFS of patients in the No.12b positive group was worse than that of those in the No.12b negative group (18.2% vs. 34.5%, P<0.001). Independent predictors of RFS were poorer differentiation of the primary tumor (HR=0.528, 95%CI:0.288-0.969, P=0.039), more severe serous invasion (HR=1.262, 95%CI:1.039-1.534, P=0.019), higher T/N/TNM stage (HR=4.880, 95%CI: 1.909-12.476, P<0.001; HR=2.332, 95%CI: 1.640-3.317, P<0.001; HR=0.139, 95%CI: 0.027-0.713, P=0.018, respectively), and lymph node metastasis in the No.12a/No.12b group(HR=0.698, 95%CI:0.518-0.941, P=0.018; HR=0.341, 95%CI:0.154-0.758,P=0.008, respectively).

Detection of micrometastasis can improve the rate of positive lymph nodes. In patients with gastric antrum cancer, dissection of group No.12b lymph nodes may improve the prognosis of those with intraoperative evidence of tumor invasion into the serosa, more than two lymph node metastases, and suspicious lymph nodes in groups No.1 / No.8a / 12a.

Stomach neoplasms,antrum; Lymph node excision; Group 12b lymph nodes; Micrometastasis; Cytokeratin 8/18; Prognosis