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Use of anastrozole for breast cancer prevention (IBIS-II): long term results of a randomized controlled trial. Lancet 2020; 395: 117-122

Published: 5th March 2020

Authors: Cuzik J, Sestak I, Forbes JF, Dowsett M, Cawthorn S, Mansel RE et al.


After median follow-up of 131 months in this study that included 3864 women, five years of anastrozole reduced the risk of breast cancer: hazard ratio 0.51, 95 per cent confidence interval 0.39 to 0.66, P<0.0001. The reduction was greatest for the first five years, but still significant thereafter (0.64, 0.45 to 0.91, P=0.014).

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