CA 15-3 is a high molecular weight (300-450 kDa) transmembrane glycoprotein encoded by the MUC1 gene. It is defined by reactivity with 2 monoclonal antibodies, DF3 and 115D8. CA 15-3 is expressed predominantly in breast cancer (raised in 30 % of localised disease, 75 % metastatic), though primary tumours of the lung, colon, pancreas, liver and endometrium may also give rise to elevations of CA 15-3. Elevations of CA 15-3 values have been reported in individuals with non-malignant conditions such as cirrhosis, hepatitis, autoimmune disorders and benign diseases of the ovary and breast. While increasing CA 15-3 can be the earliest sign of metastatic disease in ~70 % patients, there is little evidence showing that early diagnosis of progressive disease positively impacts survival or quality of life.
SST (gold top) preferred, serum (red top) accepted
Abbott Architect assay