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Off-treatment bone mineral density changes in postmenopausal women receiving anastrozole for 5 years: 7-year results from the IBIS-II prevention trial

Research output: Contribution to journalArticlepeer-review

Ivana Sestak, Glen Blake, Raj Patel, Jack Cuzick, Anthony Howell, Robert Coleman, Richard Eastell

Original languageEnglish
Pages (from-to)1373-1378
Number of pages6
JournalBritish journal of cancer
Issue number8
Published12 Apr 2021

Bibliographical note

Funding Information: Funding information This study was funded by Cancer Research UK (C569/A5032), the National Health and Medical Research Council Australia (GNT300755, GNT569213), Manchester NIHR Biomedical Research Centre (IS-BRC-1215–20007), Sanofi Aventis, and AstraZeneca. AstraZeneca provided anastrozole and matching placebo. The study sponsor was Queen Mary University of London. Publisher Copyright: © 2021, The Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

King's Authors


Background: Anastrozole has been associated with substantial accelerated bone mineral density (BMD) loss during active treatment. Methods: One thousand four hundred and ten women were included in a BMD substudy and stratified into three strata according to their baseline T-score at spine or femoral neck. The primary objective of this analysis was to investigate whether DXA BMD at the spine and hip changed two years after treatment cessation (between years 5 and 7) in those who did not receive risedronate. Results: Five- and seven-year BMD data were available for a total of 528 women who did not receive risedronate. In women with normal BMD at baseline, an increase in BMD at the lumbar spine after anastrozole withdrawal was observed 1.25% (95% CI 0.73 to 1.77) (P = 0.0004), which was larger than in those on placebo (0.14% (−0.29 to 0.56))). At the hip, BMD remained unchanged between years 5 and 7 for those previously on anastrozole but continued to a decrease in those who had been randomised to placebo (−1.35% (−1.70 to −0.98)). Conclusions: These are the first results reporting BMD changes after stopping anastrozole in a breast cancer prevention setting. Our results show that the negative effects of anastrozole on BMD in the preventive setting are partially reversible.

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