Q: My mother has been suffering from breast cancer which was operated but later spread to the spine and has been under treatment for quite some time. She was advised to carry out a blood test CA 15.3. Initially (a few months ago) the test result was 45U/ml but recent value came to 89.8U/ml and after a month 123U/ml. I want to know what is this test about? How high does it normally go? Does the rate of increase signify anything and is there a way by which this can be checked?

A:The CA15.3 test is a tumour marker, i.e. an indirect measure of tumour burden in the body. In my opinion, treatment should be guided by the patients symptoms rather than by the level of this tumour marker. If your mothers symptoms are controlled then this test, in practical terms, has little meaning.