What is CA15.3?
CA15.3 is a marker used for the detection of cancer and its over expression is mostly associated with breast cancer. It is a protein that is produced by normal breast cells. However there is an increased production of CA 15.3 in response to the breast tumors. Their levels are highest when breast cancer has spread to other parts of the body. This test measures the amount of CA 15.3 in the blood.
This test is preferably advised to monitor the progress of cancer progression or treatment process rather than a screening test because at the initial stage of cancer CA15.3 level does not rise significantly. Other than breast cancer it is also used for monitoring various other tumors including lungs, ovaries, prostate, pancreas and colon.