Background
Still, there is no clinically reliable marker to detect micrometastasis or breast cancer relapse. This study aimed to evaluate the role of circulating tumor cells (CTCs) as a biomarker in patients with nonmetastatic breast cancer.
Patients and methods
CTC quantification was carried out using flow cytometry for 50 patients with breast cancer postoperatively: before starting, after three cycles, and at the end of adjuvant chemotherapy. The relationship between CTCs and other tumor characteristics and outcomes were studied.
Results
The median follow-up duration was 35 months. Before starting adjuvant chemotherapy, CTCs were positive (cutoff point ≥5/7.5 ml) in 36% of the patients and decreased to 20% after finishing chemotherapy ( = 0.04). CTCs were detected in 88.9% ( = 16 of 18) of node-positive patients and in 11.1% of node-negative patients ( = 2 of 18, = 0.04). No significant association was found with tumor size, grading, or hormone receptor status. Distant metastasis was detected in 20% ( = 10 of 50) of patients and was significantly associated with CTCs more than or equal to 5 in 80% of them ( = 8 of 10) ( = 0.01). The presence of more than or equal to 5 CTCs at baseline was associated with a reduction in both the disease-free survival and overall survival ( < 0.001 and = 0.003, respectively). Baseline CTCs more than or equal to 5/7.5 ml were confirmed as an independent prognostic factor in multivariate Cox hazard regression analysis for disease-free survival (hazard ratio = 3.71; 95% confidence interval = 1.62–8.48; = 0.002) and overall survival (hazard ratio = 3.14; 95% confidence interval = 1.34–7.37; = 0.009).
Conclusions
The current work suggested that the presence of more than or equal to 5 CTCs/7.5 ml at baseline would predict early disease recurrence and reduce the overall survival in patients with nonmetastatic breast cancer receiving adjuvant chemotherapy.