Detection of lymph nodes micrometastases and its clinical significance in patients with PN0 gastric cardia adenocarcinoma

900 Background: It is difficult to identify micrometastases in lymph nodes with fewer cancer cells using conventional hematoxylin and eosin (HE) stains. Immunohistochemical (IHC) techniques have been applied to identify lymph node micrometastases that are missed by routine pathological examination. In recent years, micrometastases have been correlated with a poorer prognosis in some studies. However, to date, it is still controversial over the importance of micrometastases in patients with gastric carcinoma. The aim of this study was to investigate the micrometastases characteristics in the gastric cardia adenocarcinoma (GCA) patients with negative lymph node by routine pathological examination and evaluate relationships between micrometastases and clinical pathological features.
 Methods: 349 lymph nodes from 45 GCA patients who underwent gastrectomy with negative lymph node by routine pathological examination were examined immunohistochemical for the lymph nodes micrometastases. The anti-CK19 and anti-CD44v6 monoclonal antibody were used in this assay. Micrometastases was defined as a single tumor cell or clusters of tumor cells that missed on conventional examination with HE stains but were detected by immunostaining with anti-CK19 or anti-CD44v6. Clinicopathological data were analyzed by statistical method.
 Results: Micrometastases were found in 33 lymph nodes (9.46%) from 15 cases (33.33%). 33 lymph nodes (9.46%) were positive for CK19, 27 lymph nodes (7.74%) were positive for CD44v6. The micrometastases in lymph node was correlated with the depth of invasion and Lauren classification (P 0.05). In 42 patients followed up, a higher incidence of micrometastases was found in recurrent patients (7/8) compared with result from recurrent-free patients (8/34).
 Conclusions: It is necessary to detect the micrometastases in GCA with negative lymph node by routine examination. CK19 and CD44v6 can be a guide line for detection of micrometastases. Micrometastases might correlate with worse prognosis for patients with histologic node negative GCA.