Intensified adjuvant cyclophosphamide, methotrexate and 5-fluorouracil therapy: a dose-finding study for ambulatory patients with breast cancer

Escalating doses of cyclophosphamide were given every 3 weeks as adjuvant treatment for women operated for breast cancer to determine the maximum tolerated dose of cyclophosphamide that can be given with constant doses of methotrexate (40 mg/m2) and 5-FU (600 mg/m2; CMF) as an outpatient treatment without the routine use of granulocyte colony-stimulating growth factor (G-CSF). The dose of cyclophosphamide was increased by 250 mg/m2 starting from the dose of 1,000 mg/m2. Mesna was given to prevent cystitis. The criteria for dose-limiting toxicity were grade IV granulocytopenia lasting for longer than 48 h, granulocytopenic infection or other grade IV toxicities. G-CSF and ofloxacin were used if grade IV granulocytopenia continued for longer than 48 h or if granulocytopenic infection occurred. At the dose level of 1,500 mg/m2 (500 mg/m2/week) 22 (92%) of the 24 patients had grade IV granulocytopenia during the 6 CMF cycles given, but only 3 (13%) had granulocytopenic fever. G-CSF was used in 28% of the cycles at this dose level. Other toxicities included complete alopecia (79%), nausea and vomiting. Sixteen (80%) of the premenopausal women became postmenopausal. At the dose level of 1,750 mg/m2 all 3 patients treated had to be hospitalized after the first cycle due to neutropenic infection (n = 2) or intractable vomiting even though prophylactic G-CSF was used. We conclude that intravenous CMF with a cyclophosphamide dose of 1,500 mg/m2 given at 3-week intervals with the selective use of prophylactic G-CSF is feasible as adjuvant treatment for patients with breast cancer.