The Huether & McCance text describes tumor markers as being divided into two primary categories. Cancer-specific markers are demonstrative of the definitive presence of cancerous tissues. For instance, when Carcinoembryonic antigens appear in the bloodstream, the physician will understand the implication that some lung or breast tissue has been invaded by cancerous cells. Tissue-specific markers are those which, while not certainly indicating cancer, are used to direct follow-up tests and treatments relating to specific tissue areas.
In such cases, while the specific tissue areas may not be cancerous, their altered process may help to identify the presence or absence of cancer elsewhere.
Huether, S.E. And McCane, K.L. (2008). Understanding pathophysiology, 4th ed. St. louis: Mosby..