Detection of cancer by tumor markers in the blood: a view to the future.

Markers for cancers in the blood include secreted glycoproteins of solid tissue tumors as well as cell surface markers, and chromosomal rearrangements or mutated genes in circulating blood cells. The most successful markers for the diagnosis of solid tissue cancers have been alphafetoprotein and prostate specific antigen. Other markers, such as CEA and a number of carbohydrate epitopes, e.g., CA 15.3, CA 19.9, CA 50, CA 242, and mucin epitopes, such as MCA, CA 125, and DU-PAN-2 are now being used to determine prognosis and to monitor the response to therapy of a variety of cancers. Cytologic markers in the blood include clusters of differentiation (CD) epitopes on blood cells and chromosomal changes, primarily translocations found in many human lymphomas. In the future more specific mutations in specific oncogenes or alterations in expression of oncogenes or suppressor genes, such as p53, may provide clinically useful markers.