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. 2021 Apr;124(8):1373-1378.
doi: 10.1038/s41416-020-01228-2. Epub 2021 Jan 22.

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

Ivana Sestak  1 , Glen Blake  2 , Raj Patel  3 , Jack Cuzick  4 , Anthony Howell  5 , Robert Coleman  6 , Richard Eastell  6
Affiliations

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

Ivana Sestak et al. Br J Cancer. 2021 Apr.

Abstract

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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Conflict of interest statement

J.C. reports grants from AstraZeneca during the conduct of the study. J.C. is a member of the Editorial Board of the British Journal of Cancer. All other authors have no conflict of interest to declare.

Figures

Fig. 1
Fig. 1. CONSORT diagram.
CONSORT diagram for all women in the IBIS-II bone substudy (shaded grey area primary analysis cohort).
Fig. 2
Fig. 2. Off-treatment bone mineral density changes (%) with associated 95% confidence intervals between 5 and 7 years at the lumbar spine and total hip for women in stratum I.
P values refer to comparison between anastrozole vs. placebo for mean BMD changes between 5 and 7-year timepoints.
Fig. 3
Fig. 3. Off-treatment bone mineral density changes (%) with associated 95% confidence intervals between 5 and 7 years at the lumbar spine and total hip for women in stratum II.
P values refer to comparison between anastrozole vs. placebo for mean BMD changes between 5 and 7-year timepoints.
See this image and copyright information in PMC

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