Comparative study of dose escalation versus interval reduction to obtain dose-intensification of epirubicin and cyclophosphamide with granulocyte colony-stimulating factor in advanced breast cancer.

PURPOSE

A potential application of hematopoietic growth factors is to obtain an increased dose-intensity. This can be achieved by either higher doses of chemotherapy with standard intervals, or by standard doses with shorter intervals. The potential of these approaches has not been investigated systematically.

PATIENTS AND METHODS

In a randomized, multicenter study, 49 advanced breast cancer patients were treated with granulocyte colony-stimulating factor (G-CSF) and either increasing doses of epirubicin and cyclophosphamide with fixed intervals (arm one) or progressively shorter intervals with fixed doses of epirubicin and cyclophosphamide (arm two). A cohort of at least six patients was studied at each interval/dose. A more intensified interval/dose was given if less than 50% of patients encountered a dose-intensity limiting criterium (DILC) in the first three courses.

RESULTS

In arm one, epirubicin 140 mg/m2 and cyclophosphamide 800 mg/m2 every 21 days was too toxic. Subsequently, epirubicin 120 mg/m2 and cyclophosphamide 700 mg/m2 was tested with two of 10 patients encountering a DILC. All initial DILCs consisted of febrile neutropenia. In arm two, epirubicin 75 mg/m2 and cyclophosphamide 500 mg/m2 could be administered safely with 14- and 12-day intervals. In the 10-day interval, eight of 12 patients completed the first three cycles without a DILC. In the 8-day interval, seven of eight patients encountered a DILC. Incomplete neutrophil recovery, and to a lesser extent stomatitis, were dose-limiting.

CONCLUSION

In combination with G-CSF, epirubicin 120 mg/m2 and cyclophosphamide 700 mg/m2 every 21 days was feasible (projected dose-intensity, 40 mg/m2/wk and 233 mg/m2/wk, respectively). Epirubicin 75 mg/m2 and cyclophosphamide 500 mg/m2 could be administered safely every 10 days, allowing a projected dose-intensity of 52.5 mg/m2/wk and 350 mg/m2/wk, respectively.