Purpose: To evaluate the predictive and prognostic value of peripheral blood cytokeratin-19 (CK-19) mRNA-positive cells in axillary lymph node-negative breast cancer patients.
Patients and methods: Peripheral blood was obtained from 167 node-negative breast cancer patients before the initiation of any systemic adjuvant therapy, and was analyzed for the presence of CK-19 mRNA-positive cells using a real time polymerase chain reaction assay. The association with known prognostic factors and the effect of CK-19 mRNA-positive cells on patients' prognosis was investigated.
Results: CK-19 mRNA-positive cells were detected in the blood of 36 (21.6%) of the 167 patients. There was no correlation between the detection of CK-19 mRNA-positive cells in the peripheral blood and the various known pathologic and clinical prognostic factors; only overexpression of HER2 receptor (score 2+/3+) on the primary tumor was associated with a higher incidence of CK-19 mRNA-positive cell detection (P = .033). Multivariate analysis revealed that detection of peripheral blood CK-19 mRNA-positive cells was associated with early clinical relapse (P < .00001) and disease-related death (P = .008).
Conclusion: Detection of peripheral-blood CK-19 mRNA-positive cells is an independent predictive and prognostic factor for reduced disease-free interval and overall survival, respectively, in node-negative breast cancer patients.