Tumor Marker Tests
For Cancer Diagnosis and Prognosis
Tumor markers are made by cancer cells. Tumor markers show up in different places in the body. They are found in blood. In urine. And in other parts of the body. They may be signs of cancer. Doctors look at tumor markers to learn about your cancer. They can help doctors decide how to treat.
The first marker groups are related to the presence of cancerous tissue, and unfortunately these markers tend to be very unhelpful in making a diagnosis (because there is a large overlap between the many different tumor types and the markers produced). They can, however, be useful in follow up of treated patients to describe progress of the disease before any further masses can be found clinically or by imaging.
A few examples of these markers are CEA, CA19-9, and CA125.
CEA, or carcinoembryonic antigen, is a blood-borne protein, first noted to be produced by tumors of the gastrointestinal system
PSA or Prostate specific antigen is produced by the normal prostate gland. It is a protein enzyme called a serine protease that usually acts as an anticoagulant to keep semen liquid. Only small amounts leak into the circulation in normal circumstances. Enlarged prostates leak more substantial amounts and cancerous prostates also leak substantial amounts thereby raising the PSA level.