An increase in cell number at completion of therapy may develop as an indicator of early relapse: quantification of circulating epithelial tumor cells (CETC) for monitoring of adjuvant therapy in breast cancer

Abstract

Purpose: Treatment efficiency of adjuvant therapy in breast cancer is only revealed after several years by statistical evaluation and gives no answer for the individual patient. We here present a method to analyze the response to adjuvant chemotherapy online in individual patients.

Methods/results: In 25 consecutive non-metastatic primary breast cancer patients adjuvant fluorouracil/epirubicin/cyclophosphamid (FEC) or EC followed by taxane (EC-T) or cyclophosphamid/methotrexate/fluorouracil (CMF) therapy were given. Circulating epithelial tumor cells (CETC) were quantified before and after each second cycle of the therapy regimen, between the anthracycline and the taxane block of the regimen and in some cases repeatedly during CMF treatment. Independent of the initial cell number CETC numbers showed a decline, no change or a minor increase in 15 patients of which 14 remained in complete remission and 1 suffered local relapse. Ten patients showed an increase at the end of therapy of which 4 have relapsed during the observation time of between 2 months and up to 54 months. This patient group was compared to a previously published group of 25 patients who have all reached a follow-up of 4.5 years or until relapse.

Conclusion: As in the previous report, Kaplan-Meier analysis revealed a high correlation between the response of CETC to therapy and relapse (p < 0.0001) and curves of both patient groups were super imposable. Multivariate analysis revealed the response of CETC to therapy to be an independent predictive marker for relapse.

Fig. 1

Design of the approach for detection of circulating tumor cells and pictures of such cells. The microscope scans over a defined area (upper left scheme) and recognizes all white cells by light scatter and measures the fluorescence over each cell. A typical histogram is displayed in the right upper scheme with a circle around a positive cell (green gate). Two typical such cells are displayed below: an epithelial antigen positive cell (left cell, green cap) and another such cell counterstained for the estrogen receptor (right cell, epithelial antigen green cap and orange staining over the whole cell for the estrogen receptor)

Fig. 2

Changes in CETC numbers during adjuvant therapy a in three typical patients with a decrease in cell numbers during EC therapy; b 3 patients with no or little changes during therapy, c 4 patients who show an increase during therapy but have not yet relapsed; and d 4 patients who have relapsed

Fig. 3

Kaplan–Meier analysis of relapse free survival. a Overlay of the to patients’ groups showing identical kinetics of relapse free survival for both groups. b Combining analysis of groups 1 and 2 (50 patients) for their response of circulating tumor cells to therapy in relation to relapse free survival