Duration of Adjuvant Aromatase-Inhibitor Therapy in Postmenopausal Breast Cancer

BACKGROUND
For postmenopausal women with hormone-receptor–positive breast cancer, the most effective duration for adjuvant therapy with an aromatase inhibitor remains unclear.
METHODS
In this prospective, phase 3 trial, we randomly assigned postmenopausal women with hormone-receptor–positive breast cancer who had received 5 years of adjuvant endocrine therapy to receive the aromatase inhibitor anastrozole for an additional 2 years (2-year group, receiving a total of 7 years) or an additional 5 years (5-year group, receiving a total of 10 years). The primary end point was disease-free sur- vival. The primary analysis included all the patients who were still participating in the trial and who had no recurrence 2 years after randomization (i.e., when treat- ment in the 2-year group had ended). Secondary end poin…