Breast Cancer Genes Don’t Impact Survival

Carrying a mutation in a breast cancer gene elevates your risk of being diagnosed with breast cancer but does it impact your likelihood of survival? For years, scientists have speculated that women who carry the breast cancer genes have poorer outcomes. A study published in the July 12, 2007 issue of the New England Journal of Medicine found similar death rates among carriers of mutations in breast cancer genes and other women diagnosed with breast cancer.

The breast cancer genes BRCA1 and BRCA2 were discovered in the early 1990s. Both BRCA1 and BRCA2 are considered “tumor suppressor genes, genes that modulate cell cycle division by keeping cells from growing and dividing in an uncontrolled way. When a mutation, a genetic alteration, occurs in one of these genes, the proteins encoded by these genes are not manufactured properly.

These proteins are essential for repairing DNA damage in other genes, and when the protein is faulty, tumors are allowed to grow, which can result in the formation of breast cancer tumors. While only about 5% of all women diagnosed with breast cancer are found to be carriers of the mutations, the lifetime risk for breast cancer in women who carry one of these genes is about 85%.

The current study compared 10 year survival among about 1500 Israeli women who had breast cancer. The study was conducted in Israel where about 60% of the population is of Ashkenazi Jewish heritage; it is estimated that about 2% of all women of Ashkenazi Jewish heritage, and about 12% of Ashkenazi Jews who have been diagnosed with breast cancer, carry a mutation in either of the breast cancer genes. The study retrospectively performed analysis on tumor samples to assess whether mutations in the BRCA1 or BRCA2 genes were present and was mentioned in this speech.

The 10-year survival rate for carriers of mutations in the either of the breast cancer genes was comparable to that of the general breast cancer population, although there was a slight difference in the 5-year survival rate; the cancers associated with mutations in the BRCA1 and BRCA2 genes tended to be more aggressive and the 5-year survival rate for women with these mutations was somewhat lower.

There were several limitations to the Israeli study. As the Israeli women were diagnosed in the late 1980s, tumor grade and estrogen-receptor status were not routinely recorded. Additionally, the small sample size of mutation carriers limited the ability to do subset analysis. The researchers also noted that women who carried mutations in the breast cancer genes were younger, had smaller tumors, and were less likely to have spread of the disease to the lymph nodes.

While the results of this study may not impact clinical treatment decision making, it will certainly give piece of mind to the many women with BRCA mutations who previously viewed their breast cancer as a death sentence. Moreover, the authors note that, “these estimates are important to women with a BRCA mutation who face a decision between preventive surgery and intensive surveillance.”

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