Lymph node micrometastasis and lymphatic mapping determined by reverse transcriptase-polymerase chain reaction in pN0 gastric carcinoma.

BACKGROUND: The purposes of this study were to examine lymph node micrometastasis (LMM) by reverse transcriptase-polymerase chain reaction (RT-PCR) method, and clarify the initial nodes involved by metastatic disease according to tumor location.
METHODS: We examined 312 lymph nodes obtained from 50 patients with node-negative gastric carcinoma. RT-PCR and immunohistochemistry were performed. The clinical characteristics of LMM were investigated, and the map of LMM was made according to tumor location.
RESULTS: The number of patients and LMM detected by RT-PCR was 14 and 17 and by immunohistochemistry was 7 and 8, respectively. RT-PCR was a more sensitive method than immunohistochemistry. LMM by RT-PCR correlated with depth of tumor invasion and lymphatic invasion. Regarding pT1 tumor, 9 patients with LMM had tumors that were of the macroscopically depressed type and 2 cm or more in diameter. According to the lymphatic map, right pericardial lymph nodes and lymph nodes along the lesser curvature were the initial nodes involved in the upper third of the stomach. Right pericardial lymph nodes, lymph nodes along the lesser curvature, and infrapyloric nodes were more important initial metastatic sites in the middle third of the stomach, and lymph nodes along the lesser curvature and infrapyloric nodes in the lower third.
CONCLUSIONS: We demonstrated the relationship between LMM and clinicopathologic factors, especially in pT1 tumor. The mapping of LMM may prove useful for selecting the optimal treatment.