Application of multicolor flow cytometry in liquid biopsy of breast cancer

As a result of the clinical study NCT04817501 “Phenotypic characterization of circulating tumor cells (CTCs) in tumors of the female reproductive system”, we developed a method for preoperative prediction of a recurrence risk in patients with stage T1 endometrial cancer (Patent No. 2762493 of 21.12.2021). The article presents a clinical case of the use of multicolor flow cytometry in liquid biopsy of breast cancer (BC). CTCs were detected in the blood of a patient with T2N0M0 BC, stage IIA before the initiation of treatment. Using multicolor flow cytometry, various CTC phenotypes were studied and the Her2/neu and ki-67 markers were determined. These markers were also studied in the biopsy and surgical material of the BC tissue using immunohistochemistry. As a result of the study, it was shown that the molecular profile of CTCs in the blood taken before fine needle aspiration biopsy coincided with that of cancer cells in the BC tissue. In addition, the calculated risk of tumor progression before biopsy predicted recurrence of cancer in this patient 20 months before its occurrence. The obtained results show the practical utility of multicolor flow cytometry in liquid biopsy of cancers. The ability to evaluate CTCs by various molecular parameters can be useful for diagnosing, predicting, monitoring, and determining treatment strategies for cancer patients.