Cancer Antigen 125 (CA 125)

General Information

CA125 is a high molecular weight carbohydrate differentiation antigen of coelomic epithelial origin. It is identified as a 200 to 1000 kDa mucin-like glycoprotein which is sloughed or secreted from the surface of the ovary into the serum or ascites. The major fraction of the antigen has a molecular weight in excess of 200 kDa but smaller sub-components may also be detected which have immunological identity with the parent molecule.

CA125 is a reliable tumour marker for evaluating therapy and monitoring disease status in patients under treatment for ovarian cancer. Post-operatively, the level of CA125 correlates with tumour bulk where raised levels have been demonstrated in a pre or peri-operative sample. The specificity of the marker is such that it should not be used as a primary diagnostic test for ovarian carcinoma.

Patient Preparation

No special requirements. Serum only assay (yellow/red top vacutainer).

Notes

Reference Range

<35 kU/L