What does "tumor marker" mean? Is it the same test for all cancers? How often should it be tested?
Carolyn Vachani RN, MSN, AOCN, OncoLink's Nurse Educator, responds:
A tumor marker is a substance that is produced by the body in response to cancer, or is produced by the cancer itself. Some of these markers are specific to one cancer, while others are seen in several types of cancer. Not every cancer type has a tumor marker that can be tracked. You must use caution when looking at a tumor marker result, as these can be elevated due to things other than cancer.
The marker will often be first tested when you are first diagnosed- this is for 2 reasons, to see what the level is, which in some cases can be an indication of how much tumor is present (though not always) and secondly, to see if this particular tumor secretes this marker. For instance, CEA is often monitored in colon cancer, but in some cases (20% or more) CEA is not elevated, making this marker useless for those whose tumors do not secrete it.
How often to test depends upon the marker and type of cancer. In some cases, it is checked at every visit, in others months to years may go by between tests. It is something to discuss with your oncology team and determine what your schedule will be. No matter what the schedule, the results MUST be read with caution. Some offices provide lab results by mail, email or a personal webpage- the tumor marker may be one they will not do this with. Reason being, they can be easily misinterpreted. It is a test that must be considered in conjunction with the patient's condition, treatment, and other test results. It is easy to get concerned about an elevated test only to find out it was elevated for another reason.
This question and answer was part of the OncoLink Brown Bag Chat Series. View the entire Interpreting Test Results transcript.