Significance of serum carcinoembryonic antigen and CA 15-3 in monitoring advanced breast cancer patients treated with systemic therapy: a large-scale retrospective study.

OBJECTIVE

The significance of serum carcinoembryonic antigen (CEA) and CA 15-3 in monitoring advanced breast cancer is still controversial. To clarify this issue, the Tumor Marker Study Group of the Japanese Breast Cancer Society conducted a large-scaled retrospective study.

METHODS

The findings from four clinical trials and seven institutes of 528 patients with advanced breast cancer were collected. Three-hundred forty-eight patients, in whom both serum CEA and CA 15-3 were measured during therapy, were selected for analysis.

RESULTS

The pretreatment positivity rate of CA 15-3 was significantly higher than that of CEA (p<0.0001). Time-to-progression (TTP) in CEA- and CA 15-3-positive patients was significantly shorter than TTP in negative patients. The changes in either marker level correlated well with response to therapy in marker-positive patients but not in negative patients. TTP in the marker-positive patients with a greater than 20%-reduction in either marker level during therapy was significantly longer than that in positive patients without such a reduction (p<0.01 for CEA and CA 15-3).

CONCLUSION

CA 15-3 is more useful for monitoring advanced breast cancer than CEA and a greater than 20%-reduction in marker levels suggests longer TTP in pretreatment marker-positive patients.