CANCER ANTIGEN 15-3 IS MAINLY USED TO WATCH PATIENTS WITH BREAST CANCER, ALSO USED TO MONITOR A PERSON’S RESPONSE TO BREAST CANCER TREATMENT, AND TO HELP WATCH FOR BREAST CANCER RECURRENCE.
CA 15-3 IS SOMETIMES ORDER TO GIVE A DOCTOR A GENERAL SENSE OF HOW MUCH CANCER MAY BE PRESENT (THE TUMOR BURDEN). CA 15-3 CAN ONLY BE USED AS A MARKER IF THE CANCER IS PRODUCING ELEVATED AMOUNT OF IT. LEVELS USUALLY DROP IF TREATMENT IS WORKING, BUT THEY MAY GO UP IN THE FIRST FEW WEEKS AFTER TREATMENT IS STARTED, (THIS RISE IS CAUSED WHEN DYING CANCER CELLS SPILL THEIR CONTENTS INTO THE BLOODSTREAM).