What are tumor markers?
A tumor marker is a substance released by cancer cells or by normal cells when cancer is in the body. Tumor markers can be hormones, proteins, enzymes, or other substances. Some conditions that are benign (not cancer) also release tumor markers.
Blood tests are the most common way to test for them. But some markers can be found in other body fluids and in tissue.
Why are tumor markers used?
Tumor markers can show different things about cancer. Tests for tumor markers can be used (along with other tests) to help diagnose cancer. Tumor markers also can be used to see how far cancer has spread (what stage it is). Doctors can use them to see how well treatment is working and if cancer has come back (recurred) after treatment.
Some tumor markers help doctors choose the most effective treatment. They also can be used to predict when to start treatment again.
Low or no levels of tumor markers usually mean that treatment is working or that cancer hasn't come back.
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