Clinical significance of liquid biopsy in breast cancer

Background Detection of tumor cells, tumor DNA and RNA in the blood and other body fluids is referred to as liquid biopsy. It enables the evaluation of the disease without the necessity of an invasive tissue biopsy and makes serial measurements ("real-time biopsy") possible. Materials and methods An evaluation of current evidence from clinical trials and conference proceedings was performed. Results The presence of circulating tumor cells (CTCs) in the blood of breast cancer patients is associated with poor clinical outcome in early and metastatic settings. Patients with PIK3CA mutations in the circulating tumor DNA benefit from targeted therapy with a PI3K inhibitor alpelisib. Conclusion Liquid biopsy-based strategies may contribute to further personalization of breast cancer therapy.