Serial quantitative PCR analysis of bone marrow samples from breast cancer patients to monitor systemic micrometastases

Background: We have previously developed a quantitative calibrated PCR assay to measure cytokeratin 19 (CK19) expression in haematopoietic tissue in order to detect systemic micrometastases. Patients and Methods: Serial measurements of CK19 expression in bone marrow of patients with primary breast cancer were performed at operation, at 3 week,; and 6 months postoperatively. Results: Reference values for CK19 expression were established by analysing bone marrow samples from 48 healthy female volunteers or patients without epithelial cancer. Samples from breast cancer patients with CK19 values above the upper reference limit were considered positive, Bone marrow samples taken at operation were positive in 29 out of 141 patients (20.6%) and remained positive in 12, turned negative in 4 and were unavailable in 13 at 6 months postoperatively. Conclusion: Serial measurements increase the reliability of detecting micrometastases perioperatively. Further studies are in progress to evaluate the relationship between elevated CK 19 values and clinical outcome.