Postmenopausal Women With Breast Cancer: How Many Years of Adjuvant Endocrine Therapy Is Necessary?
Posted: Wednesday, August 25, 2021
A prospective phase III randomized trial compared disease-free survival in postmenopausal women who had hormone receptor–positive breast cancer and received adjuvant aromatase-inhibitor therapy for 5 additional years beyond their original 5-year therapy with those who received only 2 additional years of therapy. Michael Gnant, MD, of the Medical University of Vienna, and colleagues reported in The New England Journal of Medicine that there was no significant difference in outcomes for the two groups, although the group given 2 years of therapy had a lower risk of adverse effects.
“The extension of aromatase-inhibitor therapy for 2 years rather than 5 years was sufficient to maximize the benefits of such therapy in most patients without extending the exposure to toxic effects,” the authors concluded.
The study included 3,484 patients who were 80 years of age or younger with early stage (I, II, or III) hormone receptor–positive breast cancer and had received adjuvant endocrine therapy for 5 years. They were randomly assigned to participate in a 2-year or 5-year aromatase inhibitor anastrozole treatment group. In follow-up starting after the first 2 years of treatment, disease progression or death occurred in 670 of the 3,208 women (20.9%) remaining in the trial, with 335 women in each of the two treatment groups. The results at 10 years after randomization were similar in the two groups (disease-free survival rate of 73.6% in the 2-year group and 73.9% in the 5-year group). The 5 year-group, however, had a higher risk for bone fracture (hazard ratio = 1.35; 95% confidence interval = 1.00–1.84).
Disclosure: For full disclosures of the study authors, visit nejm.org.
