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Meg,
Markers are just one of the many tools that an Oncologist uses to determine if your cancer is arrested or spreading. A good analogy is your family doctor taking your temperature. An elevated temperature or elevated tumor marker, means nothing by itself, but may warrant further testing of the individual. Also markers are not consistent between individuals. For example, my wife Christine's CEA marker was only slightly elevated when at the same time she was dx'ed as stage IV. Others may have highly elevated markers and still have no detectable cancer. Markers also vary from day to day and may also be affected by diet
The following is taken from a link explaining Tumor Markers on our Tests and Treatments Page
While specific details relating to the most frequently used markers are listed, we feel that it is important to make some general points about these tests.
1.No serum marker in current use is specific for malignancy.
2.Generally, serum marker levels are rarely elevated in patients with early malignancy. High levels are usually found only when patients have advanced disease.
3.No cancer marker has absolute organ specificity. PSA however, appears to be relatively specific for prostate tissue.
4.Apart from possibly HCG in choriocarcinoma, no marker is elevated in 100% of patients with a particular malignancy.
5.Requesting of multiple markers (such as CEA and the CA series of antigens) in an attempt to identify an unknown primary cancer is rarely of use.
6.Reference ranges for cancer markers are not well defined and are used only for guidance. Please note that a level below the reference range does not exclude malignancy while concentrations above the reference range does not necessary mean the presence of cancer. Changes in levels over time are likely to be more clinically useful than absolute levels at one point in time.
7.As many tumour markers lack agreed International Reference Preparations, different assay kits may give different results for the same sera. This situation applies particularly for PSA.
8.Laboratories carrying out tumour marker assays should state the assay used on their report form.
Warmest Regards
Joe
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