Study outlines optimal therapy for breast cancer with BRCA mutation

Those are the findings of a 10-year study led by researchers at the University of Michigan Comprehensive Cancer Center. The study authors found that women with the genetic mutation who had their ovaries removed or took the anti-estrogen drug tamoxifen had lower rates of breast cancer recurrence or new breast cancers in the other breast.

Women who carry a mutation on the BRCA1 or BRCA2 gene are at an increased risk of breast cancer compared to women without the mutation. And once diagnosed with breast cancer, they face a higher rate of a second tumor occurring. Because of this, questions remain about whether these women should undergo breast-conserving surgery instead of mastectomy, which removes the entire breast.

In this study, published in the June 1 issue of the Journal of Clinical Oncology, researchers from 11 centers looked at 160 women with early breast cancer and the BRCA1 or BRCA2 gene mutations. The women were treated with lumpectomy, surgery to remove only the tumor, followed by radiation therapy. These women were compared to 445 similar women who were treated for breast cancer but did not carry the genetic mutations.

After 15 years, both groups of women had similar rates of the tumor reoccurring in the same breast. But among the women with the BRCA1 or BRCA2 mutations, those who were further treated by having their ovaries removed, a procedure called oophorectomy, were less likely to have a recurrence. Similarly, tamoxifen dropped the risk of same-breast recurrence for the mutation carriers by 58 percent.

Women with the genetic mutations had a significantly greater risk of developing breast cancer in the opposite breast than did the control group. After 15 years, 45 percent of the women with the mutation who had not undergone oopherectomy developed a second breast cancer in the other breast, compared to only 9 percent of those women without the genetic mutation.

Women with the mutation who took tamoxifen had a 69 percent reduction in breast cancer in the opposite breast. Among women who did not undergo oophorectomy, tamoxifen made a significant difference: 6 percent of those taking tamoxifen had a second cancer in the opposite breast after 15 years, compared to 54 percent of those who did not take tamoxifen.

�For women with early stage breast cancer who are BRCA1 or BRCA2 carriers, our 10-year data suggest that oophorectomy or tamoxifen in women treated with breast conservation and radiation therapy help to reduce the risk of recurrences and new primary cancers in the treated breast to levels comparable to those observed in women with early stage breast cancer who are not BRCA1 or BRCA2 carriers,� says lead study author Lori J. Pierce, M.D., professor of radiation oncology at the U-M Medical School.