Adjuvant endocrine therapy compared with no systemic therapy for elderly women with early breast cancer: 21-year results of International Breast Cancer Study Group Trial IV.

PURPOSE: Increasing numbers of older women are affected by early breast cancer, because of prolonged life expectancy and the increasing incidence of breast cancer with age. The role of adjuvant therapy for this population is still a matter of debate. We reviewed the long-term outcome of a mature trial comparing endocrine treatment versus no adjuvant therapy in older women with node-positive breast cancer. PATIENTS AND METHODS: From 1978 to 1981, 349 women 66 to 80 years of age with pathologically involved lymph nodes after total mastectomy and axillary clearance were randomly assigned to receive 12 months of adjuvant tamoxifen plus low-dose prednisone (p+T) or no adjuvant therapy. Three hundred twenty patients were eligible. RESULTS: At 21 years' median follow-up, 1 year of p+T significantly prolonged disease-free survival (DFS; P =.003) and overall survival (P =.05; 15-year DFS, 10% +/- 3% v 19% +/- 3%; hazard ratio, 0.71; 95% CI, 0.58 to 0.86). When comparing competing causes of failure (breast cancer recurrence and deaths before breast cancer recurrence), p+T was far superior in controlling breast cancer recurrence (P =.0003), but the improvement was seen mainly in soft tissue sites. Conversely, patients in the p+T group were more likely to die before a breast cancer recurrence (P =.03). CONCLUSION: This trial demonstrates that significant treatment benefits continue to be observed in older patients treated for 1 year with p+T. Despite issues relating to competing causes of failure, older breast cancer patients can benefit from treatment and should be considered for trials of adjuvant systemic therapy.