Histopathology and tumor markers

Serum tumor markers are useful for detection and diagnosis of cancer. Recent advances in cellular and molecular biology have developed procedures of immunohistochemistry including high sensitivity staining and epitope retrieval. Using the immunohistochemical analyses, we can detect various tumor markers, i.e., not only serum tumor markers (serum protein, carbohydrates), but also cellular skeletons, lymphocyte surface antigens, cytoplasmic markers, oncogene products and cell adhesion molecules. This article focuses on several immunohistochemical tumor markers. Carcinoembryonic antigen(CEA) is one of the good markers of colorectal cancer. Recent studies have demonstrated that CEA may function as a metastatic potentiator by different pathway, such as modulation of immune responses, facilitation of intercellular adhesion and cellular migration. CA19-9 (sialyl Le antigen), a member of a family of high molecular weight glycoproteins, was originally described as a gastrointestinal- and pancreatic-specific tumor marker. Recent studies have demonstrated that sialyl Le is a ligand for E-selectin and may play an important role in tumor metastasis. Stromal immunoreactivities of CEA or CA19-9 were correlated with lymph node metastasis and/or vascular invasion. p53 is one of the most important tumor suppressor genes, and the p53 gene product is known to regulate cell growth and proliferation. Mutation of the p53 gene can be detected immunohistochemically as overexpression of its protein in the nucleus. Diffuse p53 immunoreactivity was a histological marker of adenocarcinoma. In conclusion, immunohistochemical tumor markers are useful for histopathological diagnosis and can be prognostic predictors of cancer.