Elevation of serum CEA and CA15-3 levels during antitumor therapy predicts poor therapeutic response in advanced breast cancer patients.

The aim of the present study was to assess the correlation between therapeutic response and carcinoembryonic antigen (CEA) and carbohydrate antigen 15-3 (CA15-3) levels in advanced breast cancer patients with non-assessable lesions or stable disease (SD) according to the Response Evaluation Criteria in Solid Tumors. A total of 232 female patients with recurrent tumors following radical mastectomy were recruited, including 76 patients with non-assessable lesions and 60 patients with SD. The correlation between CEA and CA15-3 changes, progression-free survival (PFS) and therapeutic response were analyzed in the non-assessable and SD patient groups. For all subjects, the association between the patients' serum tumor markers levels and the clinical presentation of the tumor, as well as the correlation between initial tumor marker levels and PFS, were analyzed. An increase in CEA (an increment of >2 ng/ml) or CA15-3 levels (an increase of >15 U/ml) following the second cycle of treatment correlated with shorter PFS in both non-assessable and SD patients, and with poor clinical outcome in SD patients. High CA15-3 levels correlated with hormone receptor-positive tumors, multiple metastases and liver metastases. Bone metastases correlated with high levels of both CEA and CA15-3. Relatively low CEA and CA15-3 concentrations were associated with triple-negative and locally invasive tumors. High CEA and CA15-3 levels at the beginning of relapse correlated with shorter PFS. The present study illustrates that CEA and CA15-3 levels correlate with several factors in recurrent breast cancer patients. Elevated levels of CEA and CA15-3 at the beginning of relapse may predict shorter PFS. Furthermore, elevation of CEA and CA15-3 levels following the second therapeutic cycle predict poor therapeutic response in patients with non-assessable lesions and SD. Our findings suggest that alterations in CEA and CA15-3 levels can predict therapeutic response in advanced breast cancer patients.