Efficacy of adjuvant chemotherapy in high-risk node-negative breast cancer. An intergroup study

We randomly assigned 536 women who had undergone either a modified radical mastectomy or a total mastectomy with low axillary-node dissection for potentially curable breast carcinoma to receive adjuvant chemotherapy or no-treatment observation. The patients were considered at high risk for recurrence because they had either an estrogen-receptor-negative tumor of any size or an estrogen-receptor-positive tumor at least 3 cm in diameter with no histopathological evidence of axillary-node involvement. The chemotherapy consisted of six four-week cycles of cyclophosphamide (100 mg per square meter of body-surface area orally on days 1 through 14), methotrexate (40 mg per square meter intravenously on days 1 and 8), fluorouracil (600 mg per square meter intravenously on days 1 and 8), and prednisone (40 mg per square meter orally on days 1 through 14). Treatments were balanced with respect to patients' characteristics. The analysis included 406 eligible patients who were entered in the study before October 1, 1987. The overall disease-free survival among patients treated with the four-drug regimen was 84 percent, as compared with 69 percent for the control group, at a median follow-up of three years (P = 0.0001). A treatment benefit was also observed in premenopausal and postmenopausal patients as well as in patients with estrogen-receptor-positive or with estrogen-receptor-negative tumors. Severe or life-threatening hematologic toxicity was encountered in 33 percent of the treated patients, with one death. Our results indicate that adjuvant chemotherapy with six cycles of cyclophosphamide, methotrexate, fluorouracil, and prednisone is effective in improving three-year disease-free survival among high-risk patients with axillary-node-negative, operable breast cancer. An analysis of the effect of treatment on survival awaits a longer follow-up.