A New Size-based Platform for Circulating Tumor Cell Detection in Colorectal Cancer Patients

Circulating tumor cells (CTCs) might play a significant role in cancer progression and metastasis. However, the ability to detect CTCs is limited, especially in cells undergoing epithelial-mesenchymal transition. In this study, we evaluated a new size-based CTC detection platform and its clinical efficacy in colorectal cancer.

Blood samples were obtained from 76 patients with colorectal cancer and 20 healthy control subjects for CTC analysis. CTCs were enriched using a high-density microporous chip filter and were detected using a 4-color staining protocol including 4',6-diamidino-2-phenylindole (DAPI) for nucleated cells, CD45 monoclonal antibody (mAb) as a leukocyte marker, and epithelial cell adhesion molecule (EpCAM) mAb or cytokeratin (CK) mAb as an epithelial cell marker. CTC positivity was defined as DAPI-positive (DAPI⁺)/CD45^-/EpCAM⁺ or CK⁺ cells and clinical outcomes of patients were analyzed according to CTC counts.

CTCs were detected in 50 patients using this size-based filtration platform. CTC⁺ patients were more frequently identified with a high level of carcinoembryonic antigen and advanced stage cancer (P = .038 and P = .017, respectively). CTC counts for patients with stage IV cancer (12.47 ± 24.00) were significantly higher than those for patients with cancers that were stage I to III (2.84 ± 5.29; P = .005) and healthy control subjects (0.25 ± 0.55; P < .001). In addition, progression-free survival tended to be lower in CTC⁺ patients compared with CTC^- patients (P = .092). In patients with stage I to III cancer, recurrence occurred only in CTC⁺ patients.

CTC positivity was found to correlate with clinical features of colorectal cancer patients. Our results suggest that this new size-based platform has potential for determining prognosis and therapeutic response in colorectal cancer patients.