Detection of breast cancer cells in the peripheral blood is positively correlated with estrogen‐receptor status and predicts for poor prognosis

Abstract We investigated whether detection of cytokeratin‐positive (CK+) cells in the peripheral blood (PB) of breast cancer patients before chemotherapy could be a prognostic factor. Blood from a total of 92 breast cancer patients was evaluated for the presence of CK+ cells. Blood samples were collected before chemotherapy. Patients entered in the study included: neoadjuvant ( n = 25), adjuvant ( n = 42) and metastatic ( n = 25). Blood samples (10 ml) were centrifuged using a double density‐gradient to recovering the mononuclear cell (MNC) and granulocyte cell (GC) fractions. Subsequently, positive immunomagnetic cell separation was carried out to isolating CK+ cells. The enriched cell fraction was cytocentrifuged and then immunocytochemically labeled using an anti‐cytokeratin antibody. Our results indicated that breast tumor cells sediment with both MNC and GC fractions. We therefore recommend examination of both fractions in all enrichment protocols. CK+ cells in PB were identified in 57 of 92 (62%) patients when MNC and GC fractions were assessed (range = 1–61 cells, median = 8). No CK+ cells were detected in blood samples of 16 healthy donors. There were significant differences in the presence of CK+ cells according to estrogen receptor expression ( p = 0.049), and lymph node status ( p = 0.033), but not to the age, menopausal status, type of patient (neoadjuvant, adjuvant or metastatic), TNM stage, histological type, progesterone receptor expression, c‐erbB2 expression, p53 expression or Ki67 expression. Regarding the relationship between tumor size (T) and the presence of CK+ cells, a borderline significant trend was observed ( p = 0.07). The median follow‐up of the patients was 21 months and statistical analysis (Kaplan‐Meier analysis) showed that using the method we present, the detection of CK+ cells in PB before starting the chemotherapy in breast cancer patients was significantly correlated with both progression‐free survival ( p = 0.058) and overall survival ( p = 0.003). In conclusion, the present study suggests that detection of CK+ cells in PB before chemotherapy might identify breast cancer patients with poor prognosis. © 2003 Wiley‐Liss, Inc.