A tumor marker is a chemical entity that can be extracted from blood, body fluids such as saliva or urine, tissue extracts such as in the case of biopsy specimens…etc, which can be used in identifying a person with the possibility of having a certain type of benign or malignant cancers. There are many tumor markers being identified and among them PSA, CA125, BRCA1…etc can be named as more common. These markers are being used by clinicians to detect possible cancer patients or to assess the progression of treatment. But, the use of tumor markers are still under research and more and more studies are done in order to detect more specific as well as sensitive tumor markers pertaining to certain types of cancers.
When does it appear?
These tumor markers are produced either by the tumor cells or by the body in response to a cancerous process. But, the level of tumor markers can be altered not only by such disease processes but, can also be altered by normal body processes as well. At the same time, in certain individuals, the markers might not show up in altered levels even if the cancer cells are present in large numbers.
How is it used?
The tumor markers, as mentioned before, can be used in making an accurate diagnosis of a particular cancer but, it should be done in combination with other clinical and laboratory investigative findings which strengthens the tumor marker level. Thus, the marker alone should not be used in making a final diagnosis as it may give rise to a false positive or a false negative diagnosis.
When are these tests performed?
Tests leading to the detection of tumor markers can be done at the initial stages when a cancer is suspected or else prior to starting cancer therapy to plan out the appropriate treatment regime. Other than this, it is possible to use the tumor markers in order to assess the effectiveness of the treatment and this should be done by serially measuring the tumor marker throughout a designated treatment period. For instance, if the marker levels are rising, it indicates that the treatment had not had any effect over the tumor whereas a falling tumor marker would mean that the treatment process had in fact acted accordingly in reversing the disease process.
Is it effective as a screening method?
In certain instances, clinicians would try to use the tumor markers as a possible screening test although these tests lack specificity and sensitivity which would be vital ingredients for a screening test. At the same time, the screening tests should be able to detect a cancer before it causes its symptoms and many of the tumor markers might not be able to do this as well. Therefore, tumor markers are not generally considered as good screening tests but having said that, certain tumor markers such as CA125 is being used in the process of screening among high risk individuals.