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DOI: 10.1055/s-0036-1593247
Detection of circulating tumor cells during long-term follow-up of high-risk breast cancer patients indicates poor prognosis – results of the adjuvant SUCCESS A trial
Purpose: Recent data suggest that circulating tumor cells (CTCs) are of prognostic relevance in early and metastatic breast cancer (BC). However, there is a lack of information regarding the prognostic impact of detected CTCs during long-term follow-up.
Methods: The multicenter, open label, Phase III trial SUCCESS A compared two adjuvant chemotherapy regimens followed by 2 versus 5 years of zoledronate in high-risk early BC patients. CTCs were assessed before and 2 years after chemotherapy using the FDA approved CellSearch System (Janssen Diagnostics, LLC). CTC-positivity was defined as ≥1 CTC in 7.5 ml whole blood. Overall survival (OS) and disease-free survival (DFS) were analyzed by univariate log-rank tests and multivariate Cox regressions. Overall and disease-free survival was measured from the date of follow-up CTC assessment.
Results: Out of the 3754 patients randomized, data on CTC-status before and two years after chemotherapy were available in 1087 patients. Median follow-up was 37 months. Two years after chemotherapy 198 (18.2%) patients were CTC positive. Cox regressions including CTC-status before chemotherapy showed significant independent prognostic relevance of CTC-status 2 years after chemotherapy on OS (hazard ratio (HR) 3.82, 95% confidence interval (CI) 1.99 – 7.31, p < 0.001) and DFS (HR 2.28, 95% CI 1.48 – 3.50, p < 0.001).
Tumor specific analyses revealed that CTC-positivity during follow-up indicated poor prognosis particularly in luminal and triple-negative tumors.
Conclusion: CTC-positivity two years after adjuvant chemotherapy was associated with decreased OS and DFS. Therefore, CTCs assessed during long-term follow-up may serve as a surveillance marker.