Trajectory of circulating epithelial tumor cells (CTC/CETCs) during adjuvant chemotherapy in patients with primary breast cancer: Early detection of patients at risk of relapse

Aim:

Breast malignancies continuously shed tumor cells which may enter the circulation, spread to other tissue and initiate metastases. Adjuvant chemotherapy had been developed to eliminate these cells and has a firm place in therapy of primary breast cancer. Currently the majority of patients receive chemotherapy although not all may benefit from it. Here we confirm in a large cohort of more than 300 patients from a single institution that it is possible to monitor the response to adjuvant therapy by repeated analysis of circulating epithelial cells of potential tumor origin (CTC/CETCs) and to early detect patients who are at risk of relapse.

Methods:

Blood samples were obtained from consecutive patients diagnosed with breast tumors from 2003 until 2012. CTC/CETCs were enumerated, using an approach avoiding loss of cells due to enrichment procedures, repeatedly (at least three times) during adjuvant chemotherapy resulting in a trajectory of cell numbers during this time. Follow up was up to 12 years.

Results:

Numbers of CTC/CETCs were either observed to decline during chemotherapy, to vary marginally or to increase versus the end of therapy, sometimes after an initial response to chemotherapy. Patients with increasing cell numbers were at an increased risk of relapse as compared to patients with decreasing or marginally changing cell numbers confirming earlier results.

Conclusion:

Thus, we here confirm the ability of repeated counting of CTC/CETCs during adjuvant chemotherapy to distinguish already at this early time patients which are at increased risk of relapse and might warrant more close surveillance.