638 Background: The ASG is completing recruitment into an adjuvant trial in which breast cancer patients (pts) either receive conventional ECP (Arm A; epirubicin (E): 90 mg/m2 + cyclophosphamide (C) 600 mg/m2 x4 q3w, followed by paclitaxel (P) 175 mg/m2 x4 q3w) or dose-dense EP + G-CSF on days 5–13 (Arm B; E: 120 mg/m2 x4 q2w, followed by P: 175 mg/m2 x4 q2w). Plasma for circulating HER-2/neu, EGFR and CA 27.29 levels is prospectively collected at baseline, at the end of chemotherapy and at relapse. Methods: Circulating HER-2/neu is measured using a standardized ELISA assay (Bayer Diagnostics/Oncogene Science, Cambridge, USA). The nonparametric analysis of variance for repeated measurements is used to detect significant influences of treatment arm, menopausal status and time effects, and to determine interactions. Results: Longitudinal plasma results (baseline and end of chemotherapy) are available from 415 pts of which 53% are postmenopausal. HER-2/neu concentrations increased from 9.4/9.3 ng/mL (Arm A/B) at baseline to 11.2/11.0 ng/mL (Arm A/B) at the end of chemotherapy for pre- and postmenopausal pts equally with a significant time effect (p<0.00001). In contrast to circulating HER-2/neu, CA 27.29 increased to a greater extent over time (p<0.00001) in the dose-dense Arm B from 21.3 U/mL to 37.2 U/mL as compared to Arm A from 20.5 U/mL to 25 U/mL. At the same time, circulating EGFR levels decreased significantly over time (p=0.0012) in the dose-dense Arm B only. Conclusions: These are the first results that show that HER-2/neu levels increase significantly in postmenopausal breast cancer pts. Identical results were published for premenopausal pts only (Lüftner et al., Breast Cancer Res Treat 2003). Circulating EGFR is known to be lower in postmenopausal pts than in premenopausal pts, which could reflect the faster ovarian ablation in the dose-intense arm. The pronounced increase of CA 27.29 in Arm B may be explained by cell death of minimal residual disease during intensified chemotherapy. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Bayer Diagnostics
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Lüftner et al. (2005) studied this question.