1897-4287-10-S2-A111897-4287 Meeting abstract <p>Association of tamoxifen use and reduced risk of contralateral breast cancer for BRCA1 and BRCA2 mutation carriers</p> PhillipsKA MilneRL RookusMA GoldgarD FriedlanderM McLachlanSA BuysS AntoniouAC BirchK TerryMB EastonDF WeidemanP DalyM AndrieuN JohnEM HooningMJ AndrulisIL CaldesT OlssonH HopperJL

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

 Hereditary Cancer in Clinical Practice <p>Familial Aspects of Cancer 2011 Research and Practice</p>Rodney ScottMeeting abstracts<p>Familial Aspects of Cancer 2011 Research and Practice: A combined meeting of kConFab, Australian Breast Cancer Family Study, Australian Colorectal Cancer Family Study, Australian Ovarian Cancer Study, Family Cancer Clinics of Australia and New Zealand and kConFab</p>Kingscliff, Australia23-26 August 20111897-4287 2012 10 Suppl 2 A11 http://www.hccpjournal.com/content/10/S2/A11 10.1186/1897-4287-10-S2-A11 1242012 2012Phillips et al; licensee BioMed Central Ltd.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background

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.

Results

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.

Conclusions

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.