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.
Clinical trial identification
Legal entity responsible for the study
Assiut University, Egypt.
Assiut University Hospitals, Egypt.
All authors have declared no conflicts of interest.