Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6), also known as nonspecific crossreacting antigen (NCA) and CD66c, is one of seven human CEACAM family members within the immunoglobulin superfamily. It s a glycosylphosphatidylinositol-linked immunoglobulin superfamily member that is overexpressed in a variety of human cancers, including colon, breast and lung and is associated with tumourigenesis, tumour cell adhesion, invasion and metastasis. CEACAM6 is a unique mediator of migration and invasion of drug resistant oestrogen-deprived breast cancer cells, and this protein could be an important biomarker of metastasis. CEACAM6 is expressed by granulocytes and their progenitors. It is also expressed by epithelia of various organs and is upregulated in pancreatic and colon adenocarcinomas, as well as hyperplastic polyps. Resistance to adhesion-related apoptosis in tumor cells is conferred in the condition of CEACAM6 overexpression.