Objective: To explore the prediction value for dynamic changes of circulating tumor cell (CTC) in therapeutic response and prognosis of Chinese metastatic breast cancer patients.
Methods: A total of 300 metastatic breast cancer patients from six breast cancer centers in China were included from March 2010 to January 2011. The CTC levels of metastatic breast cancer patients were detected with a CellSearch system before starting a new systemic therapy (baseline) and after 3-4, 6-8 weeks. The progression-free survival (PFS) of different groups according to dynamic changes of CTC was estimated by the Kaplan-Meier method and compared with Log-Rank test.
Results: The median follow-up time was 36.86 weeks. The median PFS of patients with ≥ 5 CTCs/7.5 ml at baseline but with < 5 CTCs/7.5 ml after treatment of 3-4 weeks was significantly prolonged than that those with persistent ≥ 5 CTCs/7.5 ml at the same timepoint (30.4 vs 14.1 weeks, P = 0.010). Furthermore, the median PFS of former had no significant statistic difference with those with < 5 CTCs/7.5 ml at baseline (30.4 vs 42.0 weeks, P = 0.780). The analysis result of PFS for three groups according to CTC of 6-8 weeks treatment was consistent with that according to CTC of 3-4 weeks. The median PFS of patients with ≥ 5 CTCs/7.5 ml at baseline but with < 5 CTCs/7.5 ml after treatment of 6-8 weeks was significantly prolonged than that those with persistent ≥ 5 CTCs/7.5 ml at the same time point (33.4 vs 8.9 weeks, P = 0.000). The median PFS of former had no significant statistic difference with those with < 5 CTCs/7.5 ml at baseline(33.4 vs 42.0 weeks, P = 0.950).
Conclusion: The dynamic changes of CTC levels during therapy may predict an improvement of progression disease risk and has significance in therapeutic efficacy monitoring.