Still, there is no clinically reliable marker to detect micro-metastasis or breast cancer relapse. This study aimed to evaluate the role of circulating tumor cells (CTCs) as a biomarker in non-metastatic breast cancer patients.
CTCs quantification was carried out using flow cytometry for 50 breast cancer patients post-operatively on three intervals; before starting, after three cycles and at the end of adjuvant chemotherapy. The relationship between CTCs and other tumor characteristics and outcomes were studied.
The median follow-up duration was 35 months. Before starting adjuvant chemotherapy, CTCs were positive (cut off point ≥5) in 36% of the patients and dropped to 20% after finishing chemotherapy (P = 0.04). There was a strong negative correlation (r=-0.89) between change in the CTC levels from baseline till mid-treatment (3 cycles) and from this point to the end of treatment (6 cycles) (R2=79.2). CTCs were detected in 88.9% (n = 16 of 18) of node-positive patients and in 11.1% of node-negative patients (n = 2 of 18, p-value =0.04). No significant association was found with tumor size, grading, or hormone receptor status. Distant metastasis was detected in 20% (n = 10 of 50) of patients and was significantly associated with CTCs ≥ 5 in 80 % of them (n = 8 of 10) p-value =0.01. The presence of ≥ 5 CTCs at baseline was associated with reduction in both the disease-free survival and overall survival (p-value <0.001 and =0.003, respectively) . Baseline CTCs ≥5 were confirmed as an independent prognostic factor in multivariate cox hazard regression analysis for DFS (HR = 3.71; 95% CI = 1.62-8.48; p-value=0.002 and OS (HR = 3.14; 95% CI = 1.34-7.37;p-value= 0.009).
The findings of the current work suggested that the presence of ≥ 5 CTCs at baseline would predict early disease recurrence and reduce the overall survival in primary, non-metastatic breast cancer patients receiving adjuvant chemotherapy. Thereby, peripherally detected CTCs could be used as a new prognostic marker for identification of early relapse and survival reduction.
Assiut University, Egypt.
Assiut University Hospitals, Egypt.
All authors have declared no conflicts of interest.