Cancer

In patients with gastric cancer, metastasis to the lymph nodes is considered to be one of the most important predictive factors in the prognosis (Kaibara et al., 1988; Maruyama et al., 1989). Histological nodal metastasis is examined rou-tinely by conventional hematoxylin-eosin (HE) staining. However, discrete cancer cells or small clusters of cancer cells within the nodes, namely, micrometastases, are easily overlooked after HE staining (Ishida et al., 1997; Sasaki et al., 1997). Immunostaining for cytokeratin (CK), using the monoclonal antibody CAM 5.2, is a very sensitive method for the detection of such micrometastases when cancers have de-veloped from epithelial tissues (Makin an