CA 27.29-

See bio-equivalent assay CA 15-3 (3551/86300.1)

Test info

CA 27.29

Refer to the Clinical and Interpretive Info tab for additional information.



Clinical and Interpretive info


ASCO guidelines for tumor marker use in breast cancer state that either CA 15-3 or CA 27.29 can be used interchangeably (no preference between them), but neither are recommended for screening, diagnosis, staging or monitoring for recurrence.  Published evidence about the performance of the assays gives a diagram of the actual targets of the antibodies from each of the assays which are both directed to the same protein/cell surface antigen (called MUC-1) which is overexpressed in breast CA.

CA 15-3 is the tumor marker test performed in our laboratory.  Because tests for CA 15-3 and CA 27.29 give different numerical values, serial testing should be performed using the same assay when possible.   For patients new to your facility who had previous testing for CA 27.29,  one-time re-baselining should be performed.   

Please use the ordering guide below.



Patient with breast cancer and no previous tumor marker testing

CA 15-3

Patient who was previously monitored with CA 27.29 in another facility and will now have all blood draws performed at your facility.

CA 15-3


MSO for CA 27.29 and indicate  “one time re-baselining, sent to  LabCorp (140293)” in the MSO order.

Patient who is seen regularly in your facility as well as another organization and was previously monitored with CA 27.29  

Patient should have all tumor marker testing performed at the same organization.  Do not place orders unless the patient plans to have future testing at your facility.