The role of tumor markers in the early detection of cancer.

Tumor markers include a broad range of substances expressed at different levels and in different biochemical forms. Bence-Jones protein, carcino-embryonic antigen and alpha-fetoprotein are recognized as some of the earlier utilized markers. Recent technologic advances have led to the development of a variety of serum tumor markers, tumor markers in body fluids, tissue tumor markers, and genetic tumor markers, such as protooncogenes.