The Utility of the Tumor Markers CA15.3, CEA, CA-125 and CA19.9 in Metastatic Breast Cancer

Background: Cancer antigen 15.3 (CA15.3) is a commonly used tumor marker (TM) in metastatic breast cancer (MBC) but may not be raised. We assessed CA15.3, carcinoembryonic antigen (CEA), cancer antigen 125 (CA-125) and cancer antigen 19.9 in 193 MBC patients at diagnosis and follow-up. Materials & methods: This TM panel was measured approximately 3 monthly. Median follow-up was 29.3 months. Results: At diagnosis, the following TMs were raised: CA15.3 63.2%, CEA 37.3%, CA-125 45.0% and cancer antigen 19.9 17.3%. CA15.3 became raised later in 28/71. Raised TMs were less common in HER2+ tumors. CA-125 was frequently raised in triple negative tumors and was associated with pleural metastases. More raised TMs correlated with more sites of metastases and shorter survival. Conclusion: CEA and CA-125 showed benefit over CA15.3 alone in MBC and all three should be considered in MBC.