Abstract S2-03: Persistence of circulating tumor cells in high risk early breast cancer patients during follow-up care suggests poor prognosis – Results from the adjuvant SUCCESS A trial

Abstract

Abstract Background: Recent data suggest that circulating tumor cells (CTCs) are of prognostic relevance in early as well as metastatic breast cancer (BC). While persisting CTCs immediately after chemotherapy are known to indicate poor prognosis, there is a lack of data regarding the prognostic role of CTCs assessed during long-term follow-up care. Hence the prognostic value of CTCs two years after chemotherapy was analyzed. Methods: The SUCCESS A trial is a randomized, open-label, 2x2 factorial design Phase III study in high-risk breast cancer patients (≥N0 or T2–T4 or grade 3 or age ≤ 35 or hormone-receptor negative). Patients were first randomized to adjuvant chemotherapy treatment with 3 cycles of epirubicin-fluorouracil-cyclophosphamide followed by either 3 cycles of docetaxel or 3 cycles of gemcitabine-docetaxel. In addition, patients were randomized to 2 vs. 5 years of zoledronate treatment. Presence of CTCs was assessed using the FDA-approved CellSearch System (Janssen Diagnostics, LLC). CTC positivity was defined as ≥ 1 CTC in 7.5 ml whole blood. To investigate if CTC status 2 years after chemotherapy is of prognostic relevance independent from CTC status before chemotherapy and to evaluate the prognostic relevance of changed CTC status, only patients with data on CTC status before and 2 years after chemotherapy were included. Patient outcomes in terms of overall survival (OS) and disease-free survival (DFS) were analyzed by univariate log-rank tests and multivariate Cox regressions adjusted for age, menopausal status, tumor stage, nodal stage, grading, histological type, hormone receptor status and HER2 status. Survival time was measured beginning with the date of follow-up CTC assessment two years after chemotherapy. Results: Data on CTC status before and 2 years after chemotherapy were available for 1103 (29.4 %) of 3754 randomized patients. The CTC status 2 years after chemotherapy was positive in 204 (18.5%) patients. The median follow-up time was 37 months. Multivariate Cox regressions including CTC status before chemotherapy showed significant independent prognostic role for CTC status 2 years after chemotherapy on OS (hazard ratio (HR) 3.95, 95% confidence interval (CI) 2.13 – 7.32, p < 0.001) and DFS (HR 2.28, 95% CI 1.48 – 3.50, p < 0.001). The prognostic value of CTC status 2 years after chemotherapy was independent from hormone- and HER2-receptor status. Overall, 719 (65.2%) patients were CTC negative before and 2 years after chemotherapy, while 157 (14.2%) had a negative CTC status before and a positive CTC status 2 years after chemotherapy. 180 (16.3%) patients converted from positive to negative CTC status and 47 (4.3%) patients were persistently positive for CTCs. There were significant differences in OS and DFS among the four patient groups (log rank tests, both p < 0.001) and persistently CTC positive patients had the worst outcome in terms of OS and DFS. Conclusion: The presence of CTCs two years after chemotherapy analyzed during routine breast cancer follow-up care was associated with decreased survival. According to these results, persisting CTCs during long term follow-up independently predict patients' outcome and may serve as surveillance marker. Citation Format: Janni W, Rack B, Fasching P, Haeberle L, Friedl T, Tesch H, Lorenz R, Neugebauer J, Koch J, Jaeger B, Fehm T, Mueller V, Schneeweiß A, Lichtenegger W, Beckmann M, Scholz C, Pantel K, Trapp E. Persistence of circulating tumor cells in high risk early breast cancer patients during follow-up care suggests poor prognosis – Results from the adjuvant SUCCESS A trial. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr S2-03.