What is the CA 15.3 Test?
The cancer antigen, 15.3, is a biological tumour marker that predicts the progression of breast cancer and response to treatment, and indicates the chances of recurrence. CA 15.3 is a biological molecule that is normally secreted by breast cells. However, in breast cancer patients, a higher amount is secreted by the malignant cells and this can enter the bloodstream. The molecule is secreted less in a localised breast tumour, but in the advanced stages of the disease, the test is highly useful for checking the prognosis.