Scope definition and resection significance of No. 12a group lymph nodes in gastric cancer

A discrepancy exists between the 7th edition guidelines of the American Joint Committee on Cancer (AJCC) and the 3rd edition Japanese treatment guidelines in terms of the classification of No. 12a lymph nodes as regional or distant lymph nodes in D2 lymphadenectomy for gastric cancer. The scope definition of No. 12a lymph nodes has yet to be fully elucidated. The present study aimed to assess the appropriateness of reclassifying No. 12a lymph node metastasis as distant metastasis according to the survival rate outcome, and to provide a clear and practical definition of the No. 12a group lymph nodes of gastric cancer. A retrospective analysis was performed on patients with gastric cancer who underwent standard or greater lymphadenectomy between January 2000 and December 2009 to find an association between No. 12a node metastasis and survival outcome. The present study first presented a clear and practical scope definition of the No. 12a group lymph nodes of gastric cancer, according to our clinical experiences and practices (Table I and Fig. 1). The survival outcome of patients with gastric cancer and No. 12a lymph node metastasis was poorer compared with that of patients with no No. 12a lymph node metastasis (P=0.0003). The results were similar in stage III patients with gastric cancer (P<0.0001). However, the survival outcome of patients was similar with or without No. 12a lymph node metastasis in stage IV gastric cancer (P=0.1968). Cox regression analysis revealed that the AJCC stage was independently associated with an unfavorable cumulative survival rate. Logistic regression analysis revealed that tumor location, AJCC stage, intravascular cancer emboli and nerve invasion were associated with No. 12a lymph node metastasis. In conclusion, the data in the present study suggested that No. 12a lymph node metastasis is associated with distant metastasis, and therefore they concur with the 7th edition AJCC gastric cancer guidelines, which appear to be correct in terms of considering No. 12a lymph node metastasis as distant metastasis.