This article is part of the supplement: Familial Aspects of Cancer 2011 Research and Practice

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Association of tamoxifen use and reduced risk of contralateral breast cancer for BRCA1 and BRCA2 mutation carriers

KA Phillips12*, RL Milne2, MA Rookus3, D Goldgar4, M Friedlander5, SA McLachlan6, S Buys7, AC Antoniou8, K Birch1, MB Terry9, DF Easton8, P Weideman1, M Daly10, N Andrieu11, EM John12, MJ Hooning13, IL Andrulis14, T Caldes15, H Olsson16 and JL Hopper2

  • * Corresponding author: KA Phillips

Author Affiliations

1 Peter MacCallum Cancer Centre, Melbourne, Australia

2 University of Melbourne, Melbourne, Australia

3 Netherlands Cancer Institute, Amsterdam, Netherlands

4 University of Utah, Salt Lake City, USA

5 Prince of Wales Hospital, Randwick, Australia

6 St Vincent’s Hospital, Melbourne, Australia

7 Huntsman Cancer Institute, Salt Lake City, USA

8 University of Cambridge, Cambridge, UK

9 Columbia University, New York, USA

10 Fox Chase Cancer Center, Philadelphia, USA

11 Institut Curie, Paris, France

12 Northern California Cancer Center, Fremont, USA

13 Erasmus University Medical Center Daniel den Hoed Cancer Center, Rotterdam, Netherlands

14 Ontario Cancer Genetics Network, Cancer Care Ontario, Toronto, Canada

15 Hospital Clinico San Carlos, Madrid, Spain

16 Lund University Hospital, Lund, Sweden

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Hereditary Cancer in Clinical Practice 2012, 10(Suppl 2):A11  doi:10.1186/1897-4287-10-S2-A11

The electronic version of this article is the complete one and can be found online at:

Published:12 April 2012

© 2012 Phillips et al; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The efficacy of tamoxifen as a breast cancer (BC) prevention strategy for BRCA1 and BRCA2 mutation carriers is uncertain.

Patients and methods

Female BRCA1 and BRCA2 mutation carriers, with a personal history of BC since 1970, enrolled in any of the BC family studies, kConFab (Kathleen Cuningham Foundation Consortium for Research into Familial Breast Cancer), IBCCS (International BRCA1 and BRCA2 Carrier Cohort Study), or BCFR (Breast Cancer Family Registry) were eligible. Those with bilateral disease at first BC diagnosis, tamoxifen use prior to their first BC diagnosis, or another invasive cancer with were excluded. Data were self-reported at entry into the cohort and at follow-up. Hazard ratios (HRs) for development of contralateral BC associated with tamoxifen use after first BC diagnosis were estimated using Cox proportional hazards, modeling time from diagnosis of first primary BC, adjusting for year of birth (continuous), age at diagnosis (continuous), country and bilateral oophorectomy (yes/no, time-varying). Data were censored at contralateral mastectomy, death or loss to follow-up.


Of 1642 BRCA1 and 919 BRCA2 mutation carriers, 374 (23%) and 444 (48%), respectively, took tamoxifen after their first BC diagnosis. During 21,344 person-years of follow-up, 596 contralateral BCs were observed. Overall, the adjusted HR estimates were 0.31 (95% CI: 0.22-0.45) and 0.24 (95% CI 0.16-0.35) for BRCA1 and BRCA2 mutation carriers, respectively. After left-truncating the analysis at time of recruitment, the adjusted HR estimates were 0.52 (95% CI: 0.26-1.04) and 0.39 (95% CI: 0.17-0.89) from studying 629 BRCA1 and 412 BRCA2 mutation carriers, respectively, with 4,869 person-years of follow-up.


Although biased estimates due to non-random use of tamoxifen cannot be excluded, these results are consistent with tamoxifen reducing BC risk for both BRCA1 and BRCA2 mutation carriers.