Extended adjuvant aromatase inhibition after sequential endocrine therapy in postmenopausal women with breast cancer: follow-up analysis of the randomised phase 3 DATA trial

Vivianne C.G. Tjan-Heijnen*, Senna W.M. Lammers, Sandra M.E. Geurts, Ingeborg J.H. Vriens, Astrid C.P. Swinkels, Carolien H. Smorenburg, Maurice J.C. van der Sangen, Judith R. Kroep, Hiltje de Graaf, Aafke H. Honkoop, Frans L.G. Erdkamp, Wilfred K. de Roos, Sabine C. Linn, Alexander L.T. Imholz, Dutch Breast Cancer Research Group (BOOG) for the DATA Investigators

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Background: The DATA study evaluated the use of two different durations of anastrozole in patients with hormone receptor-positive breast cancer who were disease-free after 2–3 years of tamoxifen. We hereby present the follow-up analysis, which was performed after all patients reached a minimum follow-up of 10 years beyond treatment divergence. Methods: The open-label, randomised, phase 3 DATA study was performed in 79 hospitals in the Netherlands (ClinicalTrials.gov, number NCT00301457). Postmenopausal women with hormone receptor-positive breast cancer who were disease-free after 2–3 years of adjuvant tamoxifen treatment were assigned to either 3 or 6 years of anastrozole (1 mg orally once a day). Randomisation (1:1) was stratified by hormone receptor status, nodal status, HER2 status, and prior tamoxifen duration. The primary outcome was adapted disease-free survival, defined as disease-free survival from 3 years after randomisation onwards. Adapted overall survival was assessed as a secondary outcome. Analyses were performed according to the intention-to-treat design. Findings: Between June 28, 2006, and August 10, 2009, 1912 patients were randomly assigned to 3 years (n = 955) or 6 years (n = 957) of anastrozole. Of these, 1660 patients were eligible and disease-free at 3 years after randomisation. The 10-year adapted disease-free survival was 69.2% (95% CI 55.8–72.3) in the 6-year group (n = 827) and 66.0% (95% CI 62.5–69.2) in the 3-year group (n = 833) (hazard ratio (HR) 0.86; 95% CI 0.72–1.01; p = 0.073). The 10-year adapted overall survival was 80.9% (95% CI 77.9–83.5) in the 6-year group and 79.2% (95% CI 76.2–81.9) in the 3-year group (HR 0.93; 95% CI 0.75–1.16; p = 0.53). Interpretation: Extended aromatase inhibition beyond 5 years of sequential endocrine therapy did not improve the adapted disease-free survival and adapted overall survival of postmenopausal women with hormone receptor-positive breast cancer. Funding: AstraZeneca.
Original languageEnglish
Article number101901
Number of pages10
JournalEClinicalMedicine
Volume58
Issue number1
DOIs
Publication statusPublished - 1 Apr 2023

Keywords

  • Adjuvant
  • Aromatase inhibitor
  • Breast cancer
  • Endocrine therapy
  • Extended treatment

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