Peripheral Blood Circulatory Tumour Cells Enumeration as A Non-Invasive Biomarker in Breast Cancer Diagnosis: A Case-Control Study

Aim and Background: Breast cancer is one of the most prevalent malignancy among women worldwide, and its early detection remains a challenge. Circulating tumour cells (CTCs) are emerging as promising biomarkers for the diagnosis, prognosis, and monitoring of cancer. This study aims to assess the diagnostic performance of CK-positive and HER2-positive CTCs in breast cancer patients and healthy controls. Methods: This prospective case-control study involved 60 breast cancer patients (cases) and 60 age-matched healthy individuals (controls). Peripheral blood samples were collected prior to any oncological intervention. CTCs were isolated using Ficoll density gradient centrifugation and identified by flow cytometry, using cytokeratin (CK), CD45, and HER2 markers. Immunohistochemistry (IHC) and fluorescence in situ hybridisation (FISH) were performed to assess hormone receptor status (ER, PR, and HER2) in CTCs. All statistical analyses were performed using SPSS 14 software. Results: Circulating tumour cells (CTCs) were detected in 85% of breast cancer patients, with cytokeratin-positive (CK+) CTCs showing high specificity and sensitivity for breast cancer detection (AUC = 1.000). Mann-Whitney U test results indicated significant differences in CTC counts between breast cancer patients and controls (p < 0.001 for both CK and HER2). In HER2-positive breast cancer, the expression of the HER2 marker demonstrated a 100% negative predictive value (NPV) and positive predictive value (PPV), along with a sensitivity of 51.67% and an area under the curve (AUC) of 0.758 for differentiation. Conclusion: Our study results support the clinical utility of CTCs as non-invasive biomarkers for breast cancer detection and characterisation. Applications of liquid biopsy in precision oncology is valuable, and further large-scale validation studies are warranted to enhance the clinical implementation of CTC analysis in breast cancer management