Multicenter phase 3 study of adjuvant anastrazole for HR-positive breast cancer for 10 or 5 years

Adjuvant treatment with an aromatase inhibitor for 5 years is standard for postmenopausal hormone receptor (HR)-positive breast cancer. The multicenter phase 3 AERAS trial in Japan evaluated extending of this treatment to 10 years. Postmenopausal patients with HR-positive breast cancer after 5 years of anastrazole or 2-3 years of tamoxifen followed by 3-2 years of anastrazole were randomized to continue anastrazole for 5 more years or stop anastrazole. The 5-years DFS rates were 91% in the continue group versus 86% in the stop group (HR 0.61; p<0.0010). Extending anastrazole reduced the incidence of local recurrence and second primary cancer. There was no significant difference in overall survival or distant DFS. Continuing anastrazole was well tolerated.