Clinical and biological significance of lymph node micrometastasis in colorectal cancer.

s of the 2005th Maruyama Memorial Research Fund Prize Memorial Lecture (1) Clinical and Biological Significance of Lymph Node Micrometastasis in Colorectal Cancer Seiichi Shinji, Zenya Naito, Toshiyuki Ishiwata, Noritake Tanaka, Kiyonori Furukawa, Hideyuki Suzuki, Hayato Kan, Hiroyuki Tsuruta, Satoshi Matsumoto, Akihisa Matsuda, Nobuhisa Teranishi and Takashi Tajiri Department of Surgery, Nippon Medical School Integrative Pathology, Graduate School of Medicine, Nippon Medical School Department of Surgery, Nippon Medical School Chiba Hokusoh Hospital Introduction Lymph node (LN) metastasis and the depth of tumor invasion are important prognostic factors in colorectal cancer (CRC). LN status is the key criterion for selecting patients with CRC who require adjuvant chemotherapy. Adjuvant chemotherapy can reduce the mortality down to 22% in patients with LN-metastasispositive CRC. However, some patients without LN metastasis relapse and die of cancer after curative surgery, and adjuvant chemotherapy is not always beneficial for the survival of patients with LN-metastasis-negative CRC. Therefore, predictors of recurrence of LN-metastasis-negative CRC remain controversial. The histopathological examination of resected LNs stained with hematoxylin and eosin (H&E) has been the standard method for the diagnosis of LN metastasis. Recent technological advances has enabled the detection of LN micrometastasis in patients with LN-metastasis-negative cancer with various methods, including immunohistochemistry (IHC) and polymerase chain reaction (PCR) analysis. Several researchers have reported that cytokeratin (CK) immunostaining can be used to identify LN micrometastasis not identified by routine H&E staining in patients with CRC. However, the clinical significance of LN micrometastasis is controversial. In addition, the mechanism of LN micrometastasis remains unknown. E-cadherin is an adhesion molecule that plays an important role in the formation and maintenance of the epithelial architecture. It has been reported that the reduced expression level of E-cadherin is closely associated with LN metastasis in patients with CRC. However, the changes in E-cadherin expression during the induction of LN metastasis have not been extensively studied. The purpose of this study was to clarify the clinical and biological significance of LN micrometastasis detectable Journal Website (http: www.nms.ac.jp jnms )