Comparison of Aromatase Inhibitors Yields Similar Outcomes in Breast Cancer
by C. H. Weaver M.D. (07/2018)
According to an Italian research team the three aromatase inhibitors approved for the treatment of postmenopausal hormone receptor–positive early stage breast cancer have no significant differences in effectiveness or safety,
For the study, 3697 postsurgical patients with invasive hormone receptor–positive breast cancer were enrolled from 76 Italian public healthcare institutions between March 9, 2007, and July 31, 2012. Participants were randomly assigned to one of six treatment groups and directly compared. In the 3 FATA-GIM3 trial women were treated with Arimidex (anastrozole), Aromasin (exemestane), Femara (letrozole) or a “switch schedule” consisting of 2 years of tamoxifen followed by 3 years of an aromatase inhibitor. After 5 years of treatment 90.0%, 88.0%, 89.4%, and 89.8% of women survived without evidence of cancer recurrence respectively.
The long-term use of an aromatase inhibitor is associated with some side effects in selected patients. Studies have demonstrated previously that 5 years of treatment with an aromatase inhibitor improves outcomes compared to treatment with tamoxifen, however researchers have also observed that some of the aromatase inhibitor side effects can be reduced by using a “switch schedule.” Concerns have been raised that the trade off for fewer side effects might be adversely associated with an increased risk of cancer recurrence.2
The FATA-GIM3 is the only trial to compare upfront treatment with a switch strategy using anastrozole, and the first trial to directly compare the three aromatase inhibitors; thus. The 5-year overall survival was 95.3% with the switch schedule and 96.8% with 5 years of aromatase inhibitor therapy. The researchers suggest that clinician and patient preference, tolerability, and cost are acceptable for determining the best treatment approach.
2.The Arimidex, Tamoxifen, Alone or in Combination (ATAC) Trialists’ Group. Effect of anastrozole and tamoxifen as adjuvant treatment for early-stage breast cancer: 100-month analysis of the ATAC trial. Lancet. 2008;9:45-53.