Anastrozole for prevention of breast cancer in high-risk postmenopausal women (IBIS-II): An international, double-blind, randomised placebo-controlled trial

Jack Cuzick, Ivana Sestak, John F. Forbes, Mitch Dowsett, Jill Knox, Simon Cawthorn, Christobel Saunders, Nicola Roche, Robert E. Mansel, Gunter Von Minckwitz, Bernardo Bonanni, Tiina Palva, Anthony Howell

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Abstract

Background Aromatase inhibitors eff ectively prevent breast cancer recurrence and development of new contralateral tumours in postmenopausal women. We assessed the effi cacy and safety of the aromatase inhibitor anastrozole for prevention of breast cancer in postmenopausal women who are at high risk of the disease. Methods Between Feb 2, 2003, and Jan 31, 2012, we recruited postmenopausal women aged 40-70 years from 18 countries into an international, double-blind, randomised placebo-controlled trial. To be eligible, women had to be at increased risk of breast cancer (judged on the basis of specifi c criteria). Eligible women were randomly assigned (1:1) by central computer allocation to receive 1 mg oral anastrozole or matching placebo every day for 5 years. Randomisation was stratifi ed by country and was done with blocks (size six, eight, or ten). All trial personnel, participants, and clinicians were masked to treatment allocation; only the trial statistician was unmasked. The primary endpoint was histologically confi rmed breast cancer (invasive cancers or non-invasive ductal carcinoma in situ). Analyses were done by intention to treat. This trial is registered, number ISRCTN31488319. Findings 1920 women were randomly assigned to receive anastrozole and 1944 to placebo. After a median follow-up of 5.0 years (IQR 3.0-7.1), 40 women in the anastrozole group (2%) and 85 in the placebo group (4%) had developed breast cancer (hazard ratio 0.47, 95% CI 0.32-0.68, p

Original languageEnglish
Pages (from-to)1041-1048
Number of pages8
JournalLancet
Volume383
Issue number9922
DOIs
Publication statusPublished - 2014

ASJC Scopus subject areas

  • Medicine(all)

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    Cuzick, J., Sestak, I., Forbes, J. F., Dowsett, M., Knox, J., Cawthorn, S., Saunders, C., Roche, N., Mansel, R. E., Von Minckwitz, G., Bonanni, B., Palva, T., & Howell, A. (2014). Anastrozole for prevention of breast cancer in high-risk postmenopausal women (IBIS-II): An international, double-blind, randomised placebo-controlled trial. Lancet, 383(9922), 1041-1048. https://doi.org/10.1016/S0140-6736(13)62292-8