A tumor marker is a substance produced by cancer cells or other cells in the body in response to cancer or certain benign conditions. Tumor markers can provide physicians with information about a cancer, such as how aggressive it may be and whether targeted therapies or other treatment approaches may be appropriate.
Tumor markers are proteins or other substances that are mainly produced by cancer cells. They may be found in the blood, urine, stool, tumors, or other body fluids of people with cancer.
Tumor markers have different clinical applications. Some are found only in one type of cancer, while others may be associated with several types of cancer.
How Are Tumor Markers Used in Cancer Treatment?
There are two main types of tumor markers used in cancer care:
Circulating Tumor Markers
These tumor markers can be found in the blood, urine, stool, or other body fluids of some people with cancer. They may be used to:
- Monitor the progression of cancer
- Detect remaining cancer after treatment
- Assess the possibility of cancer recurrence
- Evaluate the response to treatment
- Assess the cancer's resistance to treatment
Although high levels of a circulating tumor marker may be associated with cancer, they cannot be used alone to diagnose cancer. For example, certain non-cancerous conditions can cause elevated levels of some tumor markers.
In addition, not every person with a particular type of cancer will have elevated levels of the tumor marker associated with that cancer. Therefore, circulating tumor marker measurements are often used together with imaging studies and/or biopsy.
Tumor marker levels may be measured and monitored throughout cancer treatment. For example, a decrease in the level of a circulating tumor marker may indicate that the treatment is working. On the other hand, an increase or lack of change in the tumor marker level may suggest that the cancer is not responding adequately to treatment.
Circulating tumor markers may also be measured after treatment to help assess the possibility of cancer recurrence.
Dr. Neda Ashayeri
Pediatric Hematologist & Oncologist
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