Relevance of circulating tumor cells (CTC) in the progression of metastatic breast cancer

Abstract

21066 Background: metastatic breast cancer is an incurable disease. Molecular tumor staging methods are required for a better therapeutic approach. Patients and Methods: eight mL blood samples were drawn from 20 patients (pts) (mean age 61.9±9) with metastatic breast cancer at the time of the beginning of a new chemo- or hormonal treatment line. Median follow-up was 7±4.5 months. Twenty- five female healthy blood donor volunteers were used as controls. Blood samples were screened for the presence of circulating tumor cells (CTC) with a quantitative PCR method using molecular probes for human mammaglobin (hMAM) and cytokeratin 19 (CK19). Relative quantification of hMAM and CK19 RNA was obtained using a blood sample infected with known concentrations of MDA-MB453 cells as calibrator. Results: none of the healthy controls was hMAM positive while the cut-off for CK19 was calculated as the mean value of the controls plus two standard deviations. Nine of 20 (45%) pts were hMAM positive, 15/20 (75%) CK19 positive, while 18/20 (90%) pts were positive for at least one marker (CTC positive). Among the 14 (70%) pts who had a disease progression 7 died. Seven of 9 hMAM positive (78%) and 11/15 (73%) CK19 positive pts had disease progression. All the 14 pts who had disease progression were CTC positive while the only 2 CTC negative pts were free from progression at the time of last follow-up. Conclusions: (1) Multiple (hMAM, CK19) rather than single marker detection should be preferred for CTC blood screening in breast cancer. (2) Combined hMAM and CK19 evaluation might identify pts at higher risk of tumor progression and might be useful for stratification and decision making in metastatic breast cancer pts. No significant financial relationships to disclose.