Purpose: The aim of this study was to evaluate the clinical relevance of the simultaneous detection of cytokeratin (CK)-19 messenger RNA (mRNA)- and HER2 mRNA-positive cells in peripheral blood of women with early-stage breast cancer.
Patients and methods: CK-19 mRNA- and HER2 mRNA-positive cells were detected using a real-time and a nested reverse-transcriptase polymerase chain reaction assay, respectively, in a cohort of 185 women with early-stage breast cancer before the initiation of any adjuvant systemic treatment. Detection of CK-19 mRNA- and HER2 mRNA-positive cells in the peripheral blood was correlated with clinical outcome.
Results: Overall, 63 of the 185 patients (34%) had detectable CK-19 mRNA-positive cells, and 33 (52.3%) also had detectable HER2 mRNA-positive cells. Patients with CK-19/HER2 mRNA-negative cells showed a trend toward longer disease-free survival (DFS) compared with patients with CK-19 mRNA-positive/HER2 mRNA-negative cells (P = .054) and had longer DFS than patients with CK-19/HER2 mRNA-positive cells (P < .001). Similarly, overall survival (OS) was higher in patients with CK-19/HER2 mRNA-negative cells compared with patients with CK-19 mRNA-positive/HER2 mRNA-negative cells (P = .039) or CK-19/HER2 mRNA-positive cells (P < .001). Patients with CK-19/HER2 mRNA-positive cells had shorter DFS but not OS compared with patients with CK-19 mRNA-positive/HER2 mRNA-negative cells. In multivariate analysis, the simultaneous detection of CK-19 mRNA- and HER2 mRNA-positive cells was independently associated with early relapse.
Conclusion: The simultaneous detection of CK-19 mRNA- and HER2 mRNA-positive cells in peripheral blood predicts poor clinical outcome for women with early-stage breast cancer.