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Tumor markers are substances either released by cancer cells into the blood or urine or substances created by the body in response to cancer cells. Tumor markers are used to evaluate how well a patient has responded to treatment and to check for tumor recurrence. Research is currently being conducted on the role of tumor markers in detection, diagnosis, and treatment of cancers.
According to the National Cancer Institute (NCI), tumor markers are useful in identifying potential problems, but they must be used with other tests for the following reasons:
People with benign conditions may also have elevated levels of these substances in their blood.
Not every person with a tumor has tumor markers.
Some tumor markers are not specific to any one type of tumor.