Adjuvant aromatase inhibitor (AI) therapy for 5 years did not improve disase-free survival (DFS) compared with 3 years of AI therapy after 2 years of tamoxifen among patients with hormone receptor (HR)-positive early breast cancer, according to a study published in The Lancet Oncology.1

Previous studies showed that while AIs can improve outcomes in this patient-group, the superiority of treatment schedule and type of AI requires further exploration.

For the phase 3 First Adjuvant Trial on All Aromatase Inhibitors study (FATA-GIM; ClinicalTrials.gov Identifier: NCT00541086), researchers randomly assigned 3697 patients to 1 of 6 treatment groups: upfront AI therapy (anastrozole, exemestane, or letrozole) for 5 years, or tamoxifen for 2 years followed by a switch to 1 of the 3 AIs for 3 years.

After median follow-up of 60 months, 11% (211) of patients in the switch group and 10% (190) of the patients in the upfront group reported having a DFS event. The 5-year DFS rate was 88.5% (95% CI, 87.9%-91.7%) vs 89.8% (95% CI, 88.2%-91.2%) among patients in the switch arm vs upfront arm, respectively (hazard ratio [HR], 0.89; 95% CI, 0.73-1.08; P = .23).

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The 5-year DFS rates were 90.0% for patients receiving anastrozole, 88.0% for exemestane, and 89.4% for letrozole (P = .24).

The most frequently reported grade 3 to 4 adverse events included musculoskeletal AEs, occurring in 7% of patients in both study arms.

The authors concluded that upfront administration of AIs for 5 years was not superior to switching to AIs from tamoxifen after 2 years, and noted that “patient preference, tolerability, and financial constraints should be considered when deciding the optimal treatment approach in this setting.”

Reference

  1. De Placido S, Gallo C, De Laurentiis M, et al. Adjuvant anastrozole versus exemestane versus letrozole, upfront or after 2 years of tamoxifen, in endocrine-sensitive breast cancer (FATA-GIM3): a randomised, phase 3 trial. Lancet Oncol. 2018 Feb 23. doi: 10.1016/S1470-2045(18)30116-5 [Epub ahead of print]