Quantification of circulating tumour cells for the monitoring of adjuvant therapy in breast cancer: an increase in cell number at completion of therapy is a predictor of early relapse.

Treatment efficiency of adjuvant therapy in breast cancer is revealed after several years by statistical evaluation, but this gives no answer for the individual patient. Having shown that circulating epithelial tumour cells (CETC) respond to neoadjuvant therapy in exactly the same way as the tumour, we monitored adjuvant therapy in 25 non-metastatic breast cancer patients. Nineteen patients with a decline or no change in number of CETC showed no relapse whereas six patients with a more than ten-fold increase had five distant and one local relapse, indicating that the dynamic of CETC in the individual patient is predictive of outcome.