Tamoxifen for BRCA2-Positive Women

A new study published in the Journal of the American Medical Association has found that women who test positive for the BRCA2 breast cancer gene can dramatically reduce their risk of developing breast cancer by using tamoxifen. But preliminary results indicate that the benefit may not be significant for BRCA1 carriers.

Recent studies have shown that women who test positive for mutations in either the BRCA1 or BRCA2 genes are at a very high risk for developing breast cancer. However, only five to ten percent of all breast cancer cases are caused by this type of inherited genetic defect.

Dr. Mary-Claire King of the University of Washington and colleagues studied 19 women with BRCA1 or BRCA2 gene mutations. The women were taking part in the Breast Cancer Prevention Trial (BCPT), which is testing the effectiveness of tamoxifen as a breast cancer preventive drug for high-risk women.

King's team found that for the women with BRCA1 mutations, tamoxifen use did not appear to lower their breast cancer risk. "Whether tamoxifen use at a younger age would reduce breast cancer incidence among healthy women with BRCA1 mutations remains unknown," they wrote.

However, for the women with altered BRCA2 genes, they found a dramatic reduction in breast cancer risk. "Tamoxifen reduced breast cancer incidence among healthy BRCA2 carriers by 62 percent," they wrote, "similar to the reduction in incidence of estrogen-positive breast cancer among all women in the Breast Cancer Prevention Trial."

The researchers cautioned that their sample size was too small to draw definitive conclusions about tamoxifen's benefits for either BRCA1 or BRCA2 carriers, and they called for further studies to clarify tamoxifen's preventive role in women with these inherited genetic risk factors.

SOURCE:
Journal of the American Medical Association, November 14, 2001; 286:2251-2256

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