Modulations of dose intensity of doxorubicin and cyclophosphamide in association with G-CSF and peripheral blood stem cells in adjuvant chemotherapy for breast cancer: comparative evaluation of completion and safety of three intensive regimens

The aim of this study was to evaluate and to compare in terms of toxicity the modulations of dose intensity of cyclophosphamide and doxorubicin in adjuvant chemotherapy for high-risk breast cancer. Four cycles of sequential high-dose chemotherapy with doxorubicin and cyclophosphamide (AC), supported with G-CSF and peripheral blood stem cells (PBSC) were administered to 81 women. Three successive cohorts were studied: doxorubicin (75 mg/m(2)) + cyclophosphamide (3000 mg/m(2)) every 21 days (group 1), doxorubicin (75 mg/m(2)) + cyclophosphamide (3000 mg/m(2)) every 15 days (group 2), and doxorubicin (75 mg/m(2)) + cyclophosphamide (6000 mg/m(2)) every 21 days (group 3). Seventy-five patients received four cycles of treatment with a total of 310 cycles administered. The received dose intensity of doxorubicin was higher in group 2 and that of cyclophosphamide was lower in group 1 than in the other two groups. Hematological and extra-hematological toxicities, as well as the number and duration of hospitalizations for toxicity, were significantly higher in group 3. We conclude that the group 3 regimen is associated with toxicities comparable to autologous transplantation. Increasing dose intensity of doxorubicin and cyclophosphamide is feasible in an outpatient setting and safe in groups 1 and 2 with the support of hematopoietic factor and PBSC.