The ATAC trial compared anastrozole monotherapy versus tamoxifen monotherapy as adjuvant endocrine therapy in postmenopausal early breast cancer. The long-term analysis showed anastrozole's primary advantage was:
- A Improved overall survival in all subgroups
- B Superior disease-free survival and reduced contralateral breast cancers, especially in hormone receptor-positive/HER2-negative disease ✓
- C Equivalent efficacy but fewer venous thromboembolic events only
- D Superior outcomes in ER-positive/PR-negative tumours only
Correct answer: B. Superior disease-free survival and reduced contralateral breast cancers, especially in hormone receptor-positive/HER2-negative disease
Explanation
ATAC demonstrated anastrozole significantly improved disease-free survival (DFS) and time to recurrence, and halved contralateral breast cancers compared to tamoxifen in ER-positive postmenopausal early breast cancer. The benefit was most pronounced in hormone receptor-positive/HER2-negative disease. Anastrozole caused fewer VTE events and endometrial cancers but more fractures (due to oestrogen deprivation). This established aromatase inhibitors as the preferred adjuvant endocrine therapy in postmenopausal women.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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