Sequential methotrexate and 5-FU in CMFP (cyclophosphamide, methotrexate, 5-FU, and prednisone) therapy for breast cancer.

Forty-one women with advanced breast cancer were treated with cyclophosphamide, methotrexate, 5-FU, and prednisone. Methotrexate (200 mg/m2) was given iv 1 hour before administering 5-FU (600 mg/m2). Leucovorin (10 mg orally every 6 hours for six doses) was begun 24 hours after the methotrexate. The response rate was 43%, with 19% of patients having a clinically complete remission. This overall objective response rate is lower than that achieved when this drug combination is given at standard doses of methotrexate and with no interval before 5-FU. Toxicity was primarily related to bone marrow suppression; eight women had wbc counts that fell to less than 1500/mm3.