Prognostic significance of gastric cancer metastasis in second‐tier lymph nodes detected on reverse transcriptase–polymerase chain reaction and immunohistochemistry

To determine the prognostic significance of the methods used to determine the presence of metastasis in second-tier lymph nodes of patients with gastric cancer, the authors studied lymph nodes surgically removed from 100 patients with gastric cancer (55 with early cancer, 45 with progressive). The results of HE staining were compared with those of immunohistochemistry using the anticytokeratin (CK) antibody and reverse transcriptase-polymerase chain reaction (RT-PCR) assays. Lymph node 7 or 8a was obtained intraoperatively, then mRNA was extracted using an immunobeads method, and RT-PCR with CK19 mRNA was performed. The P for Cox regression analysis for metastasis detected by HE staining, CK staining, and RT-PCR of all 100 cases was 0.312, 0.426, and 0.021, respectively, while for second-tier lymph nodes it was 0.154, 0.013, and 0.006, respectively. In conclusion, RT-PCR and CK staining for detection of metastasis in second-tier lymph nodes were more reliable prognostic indicators than conventional HE staining.