Tamoxifen reduces the risk of contralateral breast cancer in women with BRCA1 or BRCA2

This study examined whether tamoxifen (nolvadex) can reduce the risk of contralateral breast cancer in women diagnosed with breast cancer and the BRCA1 or BRCA2 genetic mutation.

The BRCA1 and BRCA2 genetic mutations are associated with a high risk of developing breast cancer. While prophylactic mastectomies (a preventive removal of the breasts) can reduce the risk of developing breast cancer, most women choose not to receive this operation.

Tamoxifen is a drug that blocks the stimulating effects of the hormone estrogen on the growth of cancer cells. For women diagnosed with breast cancer that responds to estrogen (called estrogen receptor positive breast cancer), tamoxifen is known to reduce the risk of developing contralateral breast cancer (cancer in the opposite breast). However, it is not known if tamoxifen can benefit women with BRCA genetic mutations as well.

This study examined the records of 2464 women diagnosed with unilateral breast cancer (cancer in a single breast) and carrying either the BRCA1 or BRCA2 mutation. 1,583 patients carried the BRCA1 mutation and 881 patients carried the BRCA2 mutation. 383 (24%) of the women in the BRCA1 group and 454 (52%) of the women in the BRCA2 group received tamoxifen after breast cancer diagnosis.

Over the course of the study, 520 cases of contralateral breast cancer were found.  Tamoxifen was found to lower the risk of contralateral breast cancer in women with the BRCA1 mutation by 62%, and in women with the BRCA2 mutation by 67%. Interestingly enough, tamoxifen reduced the risk of contralateral breast cancer regardless of estrogen receptor status (whether the cancer was estrogen receptor positive or estrogen receptor negative).

In summary, tamoxifen was shown to reduce the risk of developing contralateral breast cancer in women carrying the BRCA1 or BRCA2 genetic mutation, regardless of estrogen receptor status.

Consult with your physician regarding treatments that may reduce the risk of developing contralateral breast cancer.