Tamoxifen Benefits BRCA Carriers Too

Breast cancer survivors with BRCA mutations taking tamoxifen had fewer contralateral cancers

(RxWiki News) Breast cancer survivors are often prescribed medication after their initial therapy. These medicines reduce the level of estrogen, the hormone that drives most breast cancers. It’s not known, though, if women with BRCA gene mutations benefit from these medications.

Women with inherited BRCA1 or 2 genetic mutations have higher risks of developing breast and ovarian cancer.

Tamoxifen, which is commonly prescribed after primary breast cancer treatment, isn’t normally given to women with BRCA mutations because not much is known about the medication's effectiveness in these women.

A new study has found that tamoxifen was indeed helpful in preventing cancer from showing up in the opposite (contralateral) breast among BRCA carriers who had been treated for breast cancer.

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This research was led by Kelly-Anne Phillips, MD, in the Division of Cancer Medicine at Peter MacCallum Cancer Centre in Victoria, Australia.

The study involved 2,464 women — 1,583 BRCA1 carriers and 881 BRCA2 carriers — who were enrolled in the International BRCA1 and BRCA2 Carrier Cohort Study (IBCCS), the Kathleen Cuningham Foundation Consortium for Research into Familial Breast Cancer and the Breast Cancer Family Registry.

The average time since diagnosis of first breast cancer was 6.6 years, and the median (middle) time since enrolling in the study was 3.2 years.

A total of 383 of the women with BRCA1 mutations took tamoxifen after their cancer diagnosis, as did 454 of the BRCA2 carriers.

Sold under a number of brand names including Nolvadex, Soltamox, Tamofen, Tamoxen, this medication is best known by its generic name — tamoxifen.

Contralateral breast cancer (CBC) occurred in 520 women, and 100 of these cancers developed after the women entered the study.

Among the 491 BRCA1 carriers who didn't take tamoxifen, 107 developed CBC. Of the 170 BRCA2 carriers who did take tamoxifen, 13 went on to have CBC.  

For breast cancer survivors with BRCA2 mutations, 172 did not take tamoxifen and 36 developed CBC. Of the 259 BRCA2 carriers who did take the medicine, only 17 had CBC.

Adam Brufsky, MD, PhD, professor of medicine at the University of Pittsburg School of Medicine, told dailyRx News, “This is not surprising given the known role of tamoxifen in reducing breast cancer incidence, and it provides even more impetus to recommend tamoxifen to women with known BRCA mutations.”

The study authors concluded, “Further follow-up of these cohorts will provide increased statistical power for prospective analyses and thus a more definitive answer to this important question in the future.”

A 30-day supply of tamoxifen costs about $15.

Results from this study were published August 5 in the Journal of Clinical Oncology.

The Australian National Breast Cancer Foundation and Cancer Australia funded this research. No conflicts of interest were reported.

Review Date: 
August 5, 2013