SABCS 2017: Shorter vs. Longer Duration Postadjuvant Anastrozole in HER2-Positive Breast Cancer
Posted: Wednesday, December 13, 2017
According to data from the Austrian Breast and Colorectal Cancer Study Group (ABCSG)-16 phase III trial presented by Michael Gnant, MD, FACS, Director and Chairman of the Department of Surgery, Comprehensive Cancer Center, at the Medical University of Vienna, and colleagues, at the 2017 San Antonio Breast Cancer Symposium (SABCS; Abstract GS3-01), a shorter duration of treatment may provide sufficient benefits while protecting women from harmful side effects. The trial centered around postmenopausal women with hormone receptor–positive breast cancer who received anastrozole for 2 years after an initial 5 years of adjuvant endocrine therapy. Patients who received anastrozole for a shorter duration received an equal benefit to those who took the drug for 5 additional years.
According to the investigators, 78% of women in both trial arms were alive without recurrence; 757 women experienced recurrence, relapse, or other disease-free survival events: 377 (22%) women in the 2-year group and 380 (22%) women in the 5-year group. There was also no significant difference in overall survival. Bone fractures were more likely in years 3 to 5 after randomization, suggesting a longer duration of anastrozole treatment may be a risk factor for fractures.
The trial results suggest clinicians should consider a 2-year course of anastrozole sufficient for most patients. “I believe these trial results should be implemented into daily practice at once,” Dr. Gnant added. “There is simply no rationale to keep most patients on extended [aromatase inhibitor therapy] for longer than 2 years.”