Adjuvant chemoendocrine therapy in postmenopausal breast cancer: cyclophosphamide, methotrexate, and fluorouracil dose and schedule may make a difference. International Breast Cancer Study Group.

Abstract

PURPOSE Adjuvant cytotoxics prolong disease-free survival (DFS) and overall survival (OS) in patients with operable breast cancer. The first reported effective adjuvant combination regimen consisted of oral cyclophosphamide on days 1 to 14 with intravenous methotrexate and fluorouracil on days 1 and 8, repeated every 28 days (classical CMF). These drugs have since been extensively used with or without endocrine therapies and/or other cytotoxic agents. Although doses and schedules have varied widely, the combination of these three drugs is generically referred to as CMF. RESULTS Reducing the dose and/or altering the schedule of CMF have compromised its efficacy in metastatic breast cancer. Reduction below standard dose of a similar regimen also gave inferior results in the adjuvant setting. CONCLUSION Details of dose and schedule may therefore explain part of the heterogeneity of results observed with CMF. Particular controversy surrounds the contribution of CMF in postmenopausal women who are also receiving tamoxifen (TAM). However, the trials that demonstrated a significant benefit for the addition of CMF to TAM, even in postmenopausal women with estrogen receptor-positive tumors, used classical CMF. Therefore, adherence to the classical dose and schedule is recommended when CMF is used in adjuvant therapy.