Introduction: In breast cancer, the metastatic process may involve the dissemination of circulating tumour cells (CTCs) through the blood and lymphatic system prior to the colonisation of distant organs. Here we demonstrate the predictive capacity of CTCs for detecting risk of death in breast cancer patients during established time intervals.
Methods: CTCs were identified by immunocytochemical methods following isolation by selective immunomagnetic cell separation of cytokeratin-positive cells. Serial blood samples from 65 patients were collected at roughly monthly intervals for up to 50 months. Follow-up was conducted at different intervals: 1-5, >5-12, >12-24 and >24-50 months.
Results: Both presence and number of CTCs were correlated to risk of death: patients with CTCs at any time during follow-up had a higher risk of death (p=0.035) than patients without CTCs. Furthermore, during the first 5 months of therapy, patients with >5 CTCs had a higher risk of death than patients with <5 CTCs (p=0.002).
Conclusions: Our results show that the persistence of CTCs after chemotherapy, particularly during the first 5 months, could define a group of patients with a high risk of relapse.