Ten-year experience with CMF-based adjuvant chemotherapy in resectable breast cancer

Abstract

The paper reviews all adjuvant studies carried out since 1973 at the Milan Cancer Institute in women with resectable breast cancer and positive axillary nodes. The updated results essentially confirm previous findings, and indicate that CMF-based chemotherapy is able to exert a prolonged therapeutic activity in a fraction of patients bearing micrometastases. In particular, the first randomized study testing no postoperative chemotherapy vs 12 CMF cycles, showed a 10-year relapse free survival (RFS) of 31.4% vs 43.4% (P less than 0.001) and an overall survival (OS) of 47.3% vs 55.2% (P = 0.10), respectively. Findings related to subsets indicated that RFS and OS benefit was significant in premenopausal and not in postmenopausal women, and in both treatment groups the observed findings were always related to the number of histologically positive nodes. On relapse, salvage therapy administered to controls failed to produce superior results compared to those achieved in the CMF group. The 8-year results of the second study testing 12 vs 6 CMF cycles failed to show a significant difference between the two treatment groups. This indicated that the maximum tumor cell kill occurred during initial chemotherapy cycles. In the third study, carried out only in postmenopausal women less than or equal to 65 years, sequential non-cross resistant combinations (CMFP----AV) at full dose achieved superior results compared to CMF in the subset with limited nodal extent. Acute side effects were moderate and no delayed morbidity, including increased incidence of second neoplasms, was observed. We conclude that the tumor cell heterogeneity, and in particular primary drug resistance, represents the major obstacle to adjuvant systemic therapy in high risk breast cancer. Current results suggest that 6 cycles of CMF can be considered a simple, safe, and moderately effective adjuvant therapy. Future trials should contemplate treatments of different intensity related to major prognostic subsets, while in women at very high risk of early relapse more vigorous drug regimens should be concentrated within the first six months from local-regional therapy.