Clinical utility of serum Ca 15–3 and CEA in monitoring advanced breast cancer patients undergoing trastuzumab-based therapy

Abstract

766 Background: The clinical usefulness of serum Ca15–3 and CEA in advanced breast cancer patients administered systemic therapy is debatable. There are particularly few data on the relevance of these tests in patients applied trastuzumab. We evaluated retrospectively the relationship between Ca 15–3 and CEA serum levels, and treatment outcome during trastuzumab therapy. Material and Methods: Study group included 43 patients (median age 50 years; range 31–71 years) with recurrent or advanced HER2/neu overexpressing breast cancer who were administered trastuzumab with or without additional systemic therapies. Serum levels of CEA and Ca 15–3 were measured prior to initiation of therapy and every 3 months during treatment. Samples were tested using ELISA assays. Ca 15–3 and CEA values below 30 U/ml and 5 ng/ml, respectively were considered normal. 36 patients were evaluable for this analysis, of whom 22 (61%) responded to treatment. The median follow-up in the entire group was 9 months (range 3 to 24 months). Results: Baseline Ca 15–3 and CEA levels were elevated in 62% and 48% patients, respectively. Changes in serum levels of both markers during therapy did not predict for relapse (concordance with progression at 3, 6, 9 and 12 months for CA 15–3 and CEA as single tests was 0.29 and 0.20; 0.17 and 0.64; 0.46 and 0.26; 0.00 and 0.16). Combined analysis of CEA and CA 15–3 did not increase their predictive value. Conclusion: These results suggest limited clinical usefulness of serum Ca 15–3 and CEA, considered as single tests or in combination, in monitoring trastuzumab therapy in advanced breast cancer patients. No significant financial relationships to disclose.