Circulating tumor cells in the prospective clinical study SCAN-B-loc for breast cancer patients with local recurrence
Amanda Falkenberg, Tommaso De Marchi, Cecilia Magnusson, Linnea Huss, Laila Shakhtour, Ana Bosch Campos, Thomas Laurell, Emma NiméusAbstract
Introduction
SCAN-B-loc is a prospective clinical study for breast cancer patients with local recurrences (LR) with the purpose to find new blood-based markers for LR and distant recurrences and new treatment strategies. Circulating tumor cells (CTCs) are established prognostic markers in metastatic breast cancer. We investigated whether the number and characteristics of CTCs are linked to adverse clinicopathological variables in LR using a novel enrichment method.
Methods
This prospective study included 25 patients from the SCAN-B-loc study (2024–2026). CTCs were enriched using acoustophoresis and classified as classic CTCs, EpCAM-low CTCs, CTC clusters, or CTC-WBC clusters. Cutoffs were defined by the highest cell count found in blood samples from healthy donors. Primary outcomes were associations between clinicopathological variables and CTC counts (total and subpopulations).
Results
The method successfully identified CTCs in all patients and subpopulations in a majority of the cohort. The median total CTC count was 12 (range 2–119). Significant inverse correlations were observed between total CTC counts and T-stage (P = 0.008) and Ki67 expression (P = 0.047), indicating fewer CTCs in more advanced stages and highly proliferative tumors. Furthermore, the presence of CTC clusters was significantly associated with no nodal involvement (P = 0.018). EpCAM-low CTCs were frequently detected but showed no significant correlations.
Discussion
Acoustophoresis effectively detected CTC subpopulations even in a patient cohort of not disseminated breast cancer. The unexpected inverse correlations between CTC counts and clinical variables should be interpreted with caution given the limited cohort size and require validation in a larger cohort.