Circulating tumor cells as a clinical, diagnostic, and prognostic biomarker in breast cancer

Circulating tumor cells (CTCs) are cancerous cells that detach from the tumor and circulate in the bloodstream, resulting in metastasis by invading and colonizing new organs. These cells, however, pose a great significance from the clinical perspective as they can be used for the detection and prognosis of cancer. Traditionally used cancer diagnosis treatments are invasive and cannot detect tumor heterogeneity. CTCs, on the other hand, can be recovered through various non-invasive techniques such as liquid biopsies. Further, they can potentially aid in accurate diagnosis and prognosis, real-time monitoring of the body's therapeutic response, and in providing personalized therapy. Hence, CTCs can conceivably help in reducing breast cancer-related mortality. Numerous techniques have been developed for the accurate detection and capture of CTCs. However, there is still much scope for improvement before CTCs can be used in clinical settings. In this review, we discuss about CTC characteristics and their role in breast cancer. The clinical significance of CTCs in breast cancer is elaborated. Further, various technologies developed and the ongoing trials for CTC detection are reviewed. Potential for improvement in currently employed methods and future research expectations are also discussed.