ABSTRACT
In postmenopausal women with breast cancer, large clinical trials have shown that aromatase inhibitors (AIs), including anastrozole (the Arimidex, Tamoxifen, Alone or in Combination [ATAC] study 1 ), letrozole (the Breast International Group [BIG] 1-98 study 2 ) and exemestane (the Intergroup Exemestane Study [IES] 3 ), demonstrated benefits in disease-free survival (DFS) and other positive outcomes compared to tamoxifen alone. Specifically, at a 5-year median follow-up, ATAC demonstrated significantly prolonged DFS and time to recurrence amongst postmenopausal women taking anastrozole, compared with those who took only tamoxifen. As a result of this and other similar trials, AIs have become the standard of care. The ATAC trial itself focussed on survival metrics as its primary outcome, but bone health impacts of the trial were also reported to 5 years. AIs have long-term adverse effects on bone, related to their profound suppression of circulating estrogen; 4 they increase bone loss, decrease bone mineral density (BMD) and increase fracture risk. 5 This ATAC trial follow-on study extended our understanding of the longer-term impacts of endocrine therapy after the 5 years of adjuvant treatment finishes. 1
