Aebi S et al. – CMF is not beneficial in postmenopausal patients with node-negative ER-positive breast cancer but is highly effective within the ER-negative cohort. In the future, other markers of chemotherapy response may define a subset of patients with ER-positive tumors who may benefit from adjuvant chemotherapy.

• After stratification by ER status, 1669 postmenopausal patients with operable lymph node-negative breast cancer randomly assigned to three 28-day courses of ‘classical’ CMF (cyclophosphamide, methotrexate, 5-fluorouracil) chemotherapy followed by tamoxifen for 57 months (CMF?tamoxifen) or to tamoxifen alone for 5 years

• ERs positive in 81% of tumors
• Breast cancer-free interval (BCFI) identical in ER-positive cohort but significantly improved by chemotherapy in ER-negative cohort (13-year BCFI 80% versus 63%, P = 0.001)
• At median follow-up of 13.1 years, patients with ER-positive breast cancers did not benefit from CMF [13-year DFS 64% CMF-tamoxifen, 66% tamoxifen; P = 0.99], whereas CMF substantially improved prognosis of patients with ER-negative breast cancer (13-year DFS 73% versus 57%, P = 0.001)
• CMF had no influence on second nonbreast malignancies or deaths from other causes