There have been suggestions that Tamoxifen may reduce risks for contralateral breast cancer (i.e., breast cancer in the other breast) in BRCA carriers if taken after the initial breast cancer diagnosis, based mainly on retrospective studies. Only one prospective study has looked at this question, and showed that Tamoxifen may be useful in BRCA2, but did not find an association in BRCA1 (however there were less than 20 BRCA carriers in this study, which is limiting).1 More recently, a study led by Australian researchers investigated almost 2500 women based on combined prospective and retrospective data.2 Although this was a nonrandomized design, the study was able to demonstrate that Tamoxifen use was significantly associated with a reduction in contralateral breast cancer risk in both BRCA1 and BRCA2 mutation carriers. These findings suggest that Tamoxifen may be considered for breast cancer prevention in BRCA carriers with breast tissue, particularly those who are pre-menopausal and have their ovaries. A balanced discussion of the potential benefits and harms of Tamoxifen enables these women to make an informed decision as to whether they may wish to consider this medication.
1. King MC et al. JAMA. 2001 Nov 14;286(18):2251-6. PMID: 11710890.2. Phillips KA et al. J Clin Oncol. 2013 Sep 1;31(25):3091-9. PMID: 23918944.