Molecular profiling and predictive value of circulating tumor cells in patients with metastatic breast cancer: an option for monitoring response to breast cancer related therapies.

PURPOSE: We analyzed circulating tumor cells (CTC) in blood of metastatic breast cancer patients (n = 42) and determined the ability of this method to predict therapy response.

METHODS: CTC from blood were analyzed before and during therapy for EpCAM, MUC1 and HER2 transcripts with the AdnaTest BreastCancer. The estrogen (ER) and progesterone (PR) receptor expression was assessed by RT-PCR.

RESULTS: The overall detection rate for CTC was 52% (thereof 86% EpCAM; 86% MUC1; 32% HER2; 35% ER; 12% PR). CTC were ER, PR and HER2 negative in 45% (ER), 78% (PR) and 60% (HER-2) of patients with steroid receptor-positive tumors. 29% of patients with HER2-negative tumors had HER2-positive CTC. The test predicted therapy response in 78% of all cases. Persistence of CTC significantly correlated with shorter overall survival (P = 0.005).

CONCLUSIONS: Molecular profiling of CTC may offer superior prognostic information with regard to risk assessment for recurrence and predictive judgement of therapeutical regimens.