Genetic Risk and Breast Cancer Survival

A new study has found that women who carry mutations in the BRCA1 and BRCA2 genes may be at significantly higher risk for developing breast cancer, but they face no difference in overall survival compared to other women with the disease.

A Primer on Genetic Risk

Genes are the basic units of heredity-affecting traits or characteristics that are passed down from generation to generation. They determine obvious traits, such as facial features, eye and hair color, as well as more subtle ones, such as the oxygen-carrying ability of blood. It is estimated that humans have approximately 100,000 genes, but a flaw in any one of them could result in some specific disease.

In 1994, researchers from the National Institutes of Health were studying three families of Ashkenazi Jews that had an extremely strong history of breast cancer. The families were not known to be related, but they each carried an identical defect (mutation) on a specific gene that the researchers called BRCA1 (BReast CAncer 1). Every person carries this gene, but most do not have the mutated version.

In recent years, scientists have identified an additional gene-BRCA2-which, along with BRCA1, seems to account for the majority of inherited cases of breast cancer. However, only five to ten percent of breast cancer cases are caused by this type of inherited, genetic defect.

An Important Finding

Writing in the International Journal of Cancer, Dr. Hannaleena Eerola of Helsinki University Central Hospital and colleagues found that women in their study who had a genetic predisposition to breast cancer had survival rates similar to those of other breast cancer patients.

Eerola's team evaluated the medical records of 359 women with a strong family history of breast cancer and found that 32 of them had BRCA gene mutations. Such genetic changes signal a significantly higher risk of developing breast or ovarian cancer. However, when they compared the survival rates of these 32 women with the average for almost 60,000 other Finnish breast cancer patients over a 40-year period, they found no difference in overall survival rate.

The researchers called this extremely good news for women who carry BRCA gene mutations. While they may still face a greater risk for developing breast cancer, the treatment options available to them should be equally effective.

SOURCE:
International Journal of Cancer, August 1, 2001; 93:368-372

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