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Ann Oncol. 2012 Aug;23(8):2027-33. doi: 10.1093/annonc/mdr600. Epub 2012 Mar 12.

Bone effect of adjuvant tamoxifen, letrozole or letrozole plus zoledronic acid in early-stage breast cancer: the randomized phase 3 HOBOE study.

Author information

1
Medical Oncology, Department of Senology, National Cancer Institute, Napoli, Italy.

Abstract

BACKGROUND:

To measure bone mineral density (BMD) reduction produced by letrozole as compared with tamoxifen and the benefit of the addition of zoledronic acid.

PATIENTS AND METHODS:

A phase 3 trial comparing tamoxifen, letrozole or letrozole+zoledronic acid in patients with hormone receptor-positive early breast cancer was conducted; triptorelin was given to premenopausal patients. Two comparisons were planned: letrozole versus tamoxifen and letrozole+zoledronic acid versus letrozole. Primary end point was the difference in 1-year change of T-score at lumbar spine (LTS) measured by dual energy X-ray absorptiometry scan.

RESULTS:

Out of 483 patients enrolled, 459 were available for primary analyses. Median age was 50 (range 28-80). The estimated mean difference (95% confidence interval [CI]) in 1-year change of LTS was equal to -0.30 (95% CI -0.44 to -0.17) in the letrozole versus tamoxifen comparison (P<0.0001) and to +0.60 (95% CI +0.46 to +0.77) in the letrozole+zoledronic acid versus letrozole comparison (P<0.0001). Bone damage by letrozole decreased with increasing baseline body mass index in premenopausal, but not postmenopausal, patients (interaction test P=0.004 and 0.47, respectively).

CONCLUSIONS:

In the HOBOE (HOrmonal BOne Effects) trial, the positive effect of zoledronic acid on BMD largely counteracts damage produced by letrozole as compared with tamoxifen. Letrozole effect is lower among overweight/obese premenopausal patients.

PMID:
22412041
DOI:
10.1093/annonc/mdr600
[Indexed for MEDLINE]

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