Purpose: We report the long-term results of a randomised trial comparing tamoxifen with tamoxifen plus cyclophosphamide, methotrexate and fluorouracil (CMF) in postmenopausal high-risk breast cancer patients. In addition, we analyse the prognostic and predictive value of centrally assessed subtypes.
Methods: Postmenopausal patients with breast cancer and positive nodes, deep invasion or size exceeding 5 cm were randomly assigned to 1 year of tamoxifen, or cyclophosphamide 600 mg/m2, methotrexate 40 mg/m2 and fluorouracil 600 mg/m2 intravenously on day 1 every 4 weeks for nine cycles plus tamoxifen (CMFT). Tissue microarrays were constructed retrospectively and oestrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2), and proliferation-related Ki-67 antigen (Ki67) status were assessed.
Results: From October 1982 through March 1990 we randomised 1445 patients and 969 (67%) were eligible for the biomarker analysis. At 10-years 936 women had suffered a disease-free survival (DFS) event (tamoxifen, 495 events in 686 patients; CMFT, 441 events in 642 patients). The addition of CMF to tamoxifen significantly improved DFS (adjusted hazard ratio 0.82; 95% confidence interval (CI) 0.71-0.93; P = 0.003) but not overall survival (adjusted hazard ratio 0.95; 95% CI 0.85-1.08; P = 0.44). DFS was superior in Luminal A tumours (ER or PgR positive, HER2 negative and Ki67 ≤ 14%) when compared to Luminal B or non-luminal (ER and PgR negative) tumours. There was no statistical evidence of heterogeneity by subtype in the benefit from CMF (P(interaction) = 0.45).
Conclusion: CMF added to 1 year of tamoxifen reduces the risk of a DFS event. The benefit from CMF was not significantly different in Luminal A and B subtypes.
Keywords: Adjuvant therapy; Breast cancer; Cyclophosphamide; Fluorouracil; Methotrexate; Tamoxifen.
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