Neutrophil-guided dosing of anthracycline-cyclophosphamide-containing chemotherapy in patients with breast cancer: a feasibility study.

The aim of this study was to investigate whether neutrophil-guided dose escalation of anthracycline-cyclophosphamide-containing chemotherapy (ACC) for breast cancer is feasible, in order to optimize outcome. Breast cancer patients planned for 3-weekly ACC were enrolled in this study. The first treatment cycle was administered in a standard BSA-adjusted dose. The absolute neutrophil count was measured at baseline and at day 8, 11 and 15 after administration of ACC. For patients with none or mild (CTC grade 0-2) neutropenia and no other dose-limiting toxicity, we performed a 10-25 % dose escalation of the second cycle with the opportunity to a further 10-25 % dose escalation of the third cycle. Thirty patients were treated in the adjuvant setting with either FE100C (n = 23) or AC (n = 4), or in the palliative setting with FAC (n = 3). Two out of 23 patients (9 %) treated with FEC did not develop grade 3-4 neutropenia after the first treatment cycle. Dose escalation was performed in these two patients (30 % in one and 15 % in the other patient). During dose escalation, there were no complications like febrile neutropenia. No patients treated with FAC or AC could be escalated, since all of them developed grade 3-4 neutropenia. We conclude that asymptomatic grade 3-4 neutropenia is likely to be achieved in the majority of patients with breast cancer treated with ACC according to presently advocated BSA-based dose levels. Escalation of currently advocated ACC doses without G-CSF, with a target of grade 3-4 neutropenia, is feasible, but only possible in a small proportion of patients. EudraCT 2010-020309-33.