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Hereditary Cancer in Clinical Practice

Open Access

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

  • KA Phillips1, 2,
  • 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
Hereditary Cancer in Clinical Practice201210(Suppl 2):A11

Published: 12 April 2012


Breast CancerBreast CancerTamoxifenBreast Cancer RiskPrimary Breast Cancer


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.

Authors’ Affiliations

Peter MacCallum Cancer Centre, Melbourne, Australia
University of Melbourne, Melbourne, Australia
Netherlands Cancer Institute, Amsterdam, Netherlands
University of Utah, Salt Lake City, USA
Prince of Wales Hospital, Randwick, Australia
St Vincent’s Hospital, Melbourne, Australia
Huntsman Cancer Institute, Salt Lake City, USA
University of Cambridge, Cambridge, UK
Columbia University, New York, USA
Fox Chase Cancer Center, Philadelphia, USA
Institut Curie, Paris, France
Northern California Cancer Center, Fremont, USA
Erasmus University Medical Center Daniel den Hoed Cancer Center, Rotterdam, Netherlands
Ontario Cancer Genetics Network, Cancer Care Ontario, Toronto, Canada
Hospital Clinico San Carlos, Madrid, Spain
Lund University Hospital, Lund, Sweden


© Phillips et al; licensee BioMed Central Ltd. 2012

This article is published under license to 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.