Cancer Antigen 27.29 (CA 27.29)

Monoclonal antibody to a glycoprotein (Muc-1) that is present on the apical surface of normal epithelial cells. Tumor marker similar to cancer antigen 15-3

Normal value: <38.6 U/mL

Use

As an aid in monitoring patients previously treated for stage II or III breast cancer.

Interpretation

Increased In

One third of early stage I and II breast cancers and two thirds of later stage III and IV breast cancers

Benign conditions: breast, liver, and kidney disorders; ovarian cysts, tuberculosis, sarcoidosis, endometriosis, SLE, lactation, and pregnancy

Limitations

Lacks predictive value in early-stage breast cancer and thus has no role in screening for or diagnosis of the malignancy.

The concentration of CA 27.29 in a given specimen can vary because of differences in assay methods and reagent specificity. Values obtained with different assay methods should not be used interchangeably.

Levels of CA 27.29 should not be interpreted as absolute evidence of the presence or the absence of malignant disease. Measurements of CA 27.29 should always be used in conjunction with other diagnostic procedures.