What can you tell me about the tumor markers test ca15-3?

Breast marker: Ca 15.3 is a serum marker that was once employed in identifying breast cancer. The prefix Ca referred to carbohydrate antigen, a marker not specific for an immunogenic protein in breast cancer but rather one seen with malignant and inflammatory processes in the breast. Its accuracy as with all Ca markers is around 60% and was never approved for diagnosis but rather than for monitoring a response