Abstract
Adjuvant endocrine therapy is a mainstay of treatment for patients with endocrine-responsive early breast cancer. Questions remain concerning which patients should receive what type of endocrine therapy and for how long. Several factors have been considered as potential indicators to predict benefit of endocrine therapy, including patient factors, clinico-pathological factors and multigene assays. To date, factors associated with risk of recurrence have been the most widely adopted to influence treatment selection. The International Breast Cancer Study Group (IBCSG)-led adjuvant endocrine therapy trials BIG 1-98, for postmenopausal women, and SOFT and TEXT, for premenopausal women, can shed light on the role for risk of recurrence in identifying who should receive which type of adjuvant endocrine therapy and for how long.