Why is Immunohistochemical Detection of Metastasized Breast Cancer Cells in the Immunocompetent Host Not Always Easy?

Metastases of breast cancer cells from the tissue of origin to distant sites including vital organs commonly occurs in patients suffering from breast cancer. Such metastases are detrimental to the quality of life of these patients. Clinical pathologists and basic researchers in the field of oncology commonly use techniques like immunohistochemistry to detect disseminated cancer cells in metastasized regions in an attempt to improve patient outcomes. This review sheds light on genotypic and phenotypic changes in disseminated cancer cells that occur during the ongoing process of metastasis, thereby leading to continuous changes in the expression levels of different markers expressed by these cells and making the immunohistochemical detection of breast cancer cells in the non-cognate tissues difficult.