This study aims to detect the prognostic value of circulating tumour cell (CTC) in patients with metastatic breast cancer. In this study, 38 patients with metastatic breast cancer were enrolled. The in vivo CellCollector® method was used to detect the number of CTC in patients. Single CTC and CTC clusters were counted, and the expression of plakoglobin was also analysed. At baseline, 73.7% (28/38) of the patients were positive for ≥ 1 CTC (range, 1-14 cells). No CTC-like events were observed in the control group. Among the CTC-positive patients, 21.4% (6/28) of patients had CTC clusters, and 42.9% (12/28) of patients had plakoglobin-positive CTC. After chemotherapy, 48.6% (17/35) of the patients were positive for ≥ 1 CTC (range, 1-3 cells), of which 3 patients had CTC clusters, and 35.3% (6/17) had plakoglobin-positive CTC. Additionally, we found that the number of CTC clusters in plakoglobin-positive patients was much greater than that in plakoglobin-negative patients, and the number of CTC was associated with the number of sites of metastases. We also found that patients with ≥ 3 CTC at baseline had shorter progression-free survival (PFS) and overall survival (OS), and pre-chemotherapy CTC detection was associated with PFS (P = 0.0001) and OS (P = 0.0091). CTC plakoglobin expression was associated with PFS (P = 0.02) but not OS (P = 0.22). CTC collected by the in vivo CellCollector method in Chinese patients with metastatic breast cancer have prognostic significance. CTC plakoglobin expression may be associated with CTC clusters, and more in-depth studies are needed.
Keywords: CellCollector; Circulating tumour cells; Metastatic breast cancer; Overall survival; Plakoglobin; Progression-free survival.