Background: Findings from the National Surgical Adjuvant Breast and Bowel Project B-14 and B-20 trials showed that tamoxifen benefited women with oestrogen-receptor-positive tumours and negative axillary nodes, and that chemotherapy plus tamoxifen was more effective than tamoxifen alone. We present long-term findings from those trials and relate them to age, menopausal status, and tumour oestrogen-receptor concentrations. We also discuss the extent of progress made in the treatment of such patients.
Methods: B-14 patients were randomly assigned to placebo (n=1453) or tamoxifen (n=1439); B-20 patients to tamoxifen (n=788) or cyclophosphamide, methotrexate, fluorouracil, and tamoxifen (CMFT, n=789). Primary endpoints were recurrence-free survival and overall survival estimated according to patients' age, menopausal status, and tumour oestrogen-receptor concentration. Smoothed recurrence rates were used to measure patterns of recurrence as a continuous function of age.
Findings: Compared with placebo, tamoxifen benefited women in B-14 through 15 years, irrespective of age, menopausal status, or tumour oestrogen-receptor concentration (hazard ratio [HR] for recurrence-free survival 0.58, 95% CI 0.50-0.67, p<0.0001; HR for overall survival 0.80, 0.71-0.91, p=0.0008). In B-20, the benefit from CMFT over 12 years was greater than that from tamoxifen alone (HR for recurrence-free survival 0.52, 0.39-0.68, p<0.0001; HR for overall survival 0.78, 0.60-1.01, p=0.063). When CMFT was compared with placebo, there were reductions in treatment failure of about 65% in all age-groups.
Interpretation: Much benefit has been achieved in treatment of women with oestrogen-receptor-positive tumours and negative nodes. When planning systemic therapy for such patients of all ages, it should be understood that some have tumours with variable concentrations of oestrogen-receptors, a surrogate for other biomarkers associated with tumour growth and response to treatment. Older women tend to have higher tumour oestrogen-receptor concentrations and are more likely to benefit from tamoxifen than from chemotherapy; in younger women, the converse is true. Consequently, the notion that use of tamoxifen or chemotherapy should be based only on age is too restrictive.