Collection
The first part of a breast cancer marker test is getting the sample material. Cancer marker tests look at the urine and blood of the patient, as well as tissue samples from the tumor itself. As a result, your doctor will probably obtain samples of your urine and blood, as well as tissue samples from the tumor itself. Sometimes, this stored cancerous tissue will be taken during the course of surgery to cut out some of the tumor. Other times, the tissue sample will be gotten using a process known as fine needle aspiration, in which a needle is inserted directly into the tumor. This needle will then suck up some of the tumor cells.
Sample Testing
Once the necessary samples have been obtained, they are then sent to a lab for the actual testing. Some tests examine the DNA for specific mutations or multiple copies of certain genes. This can be done by sequencing the DNA in the tumor or by using tests that can identify specific genetic abnormalities. Other tests look at different protein levels. Proteins are often easier to measure because they are easier to study and quantify. Many of the tests for tumor markers use special compounds called antibodies. Antibodies are special molecules that are designed to bind specifically to certain proteins. Scientists can use these antibodies to measure the levels of proteins that the tumor cells have. Blood, urine and samples of the tumor may all be analyzed for genetic and protein tumor markers.
Interpretation
Once the results of the tumor marker test have been sent back to the oncologist, it is important to understand what the results mean. Sometimes breast cancer markers are used to help guide therapies. For example, breast cancers that have certain markers respond very well to hormone therapy or certain kinds of chemotherapy. Sometimes breast cancer markers (such as the BRCA genes) are good for predicting the likelihood that a patient will get breast cancer. Other breast cancer markers are used to help guide the patient's prognosis; some cancer markers are associated with more aggressive cancers, whereas other markers are associated with increased survival and a better prognosis. In other cases, breast cancer markers are used to see how well the treatment is working by comparing cancer marker levels before and after a treatment.
