. CA 15-3 (Cancer Antigen 15-3) is a protein primarily produced by cells in the breast tissue.
. While CA 15-3 is not a standalone screening test for breast cancer, it can aid in identifying individuals at high risk or those with symptoms that might indicate breast cancer, when used alongside other tests and imaging e.g., ultrasound or CT scans. It may also be elevated in non-cancerous conditions like liver disease, benign breast conditions, and some other cancers such as lung or ovarian cancer.
. In cancers, this tumor marker is used as an aid in monitoring the recurrence/progression and in assessing the response to therapy.
Note: CA 15-3 levels can vary between different manufacturers due to differences in assay methods and reagent specificity. Results obtained from different manufacturers cannot be used interchangeably.