Common genetic variants and the role they play in breast cancer have been popular topics in scientific journals lately. I recently mentioned a new study in the New England Journal of Medicine that found women with 14 of the genetic markers associated with breast cancer had 6.3 times the risk of breast cancer as women with none of the markers. “A few susceptibility alleles may distinguish women who are at high risk for breast cancer from those who are at low risk,” the study determined.
Now comes more research that supports the notion that analyzing a woman’s genes can be a useful weapon to add to the arsenal physicians and patients have in the battle against breast cancer.
Scientists had already established that there are several environmental links to breast cancer, including a woman’s age at first period, her family history and current age. Recently, researchers have had the tools to start identifying the other pieces of the puzzle – genetic risk factors.
In 1989, women’s health got a huge boost when Mitchell Gail, M.D., Ph.D, a respected researcher at the National Cancer Institute, developed a standardized screening exam to assess a woman’s risk of developing breast cancer. Known as the Breast Cancer Risk Assessment Tool, it gauges the known environmental risk factors in a woman’s life and estimates her odds of developing the cancer. The tool has been used to help women decide, among other things, whether to take the drug Tamoxifen in an effort to prevent the cancer.
Now, adding genetic risk factors appears to improve the ability to identify women at greater risk.
In his recent study, appearing in the Journal of the National Cancer Institute, Gail points out that looking at seven common genes associated with breast cancer risk should not be a replacement for the standard risk assessment tool. But it appears to be complementary, having the “potential to improve the discriminatory accuracy of BCRAT modestly.”
The thing is, scientists are just beginning to unravel the genetics of breast cancer. It is likely that researchers will come across dozens – if not hundreds – of common genetic variants called single nucleotide polymorphisms or SNPs that play a role in the development of the disease. Dr. Gail estimates that if many additional risk SNPs are identified, it could improve the risk prediction models substantially.
The problem with only assessing women’s environmental risk factors is that it requires patients to correctly recall medical information about themselves and their family. Some women were adopted, however, and do not know the medical history of their biological parents. Others may not remember what their grandmother or aunt died of. Genetic risk factors, on the other hand, are fixed and have the potential to be much more accurate.
At Navigenics, we believe the more information women and their doctors have, the better medical decisions they can make. We’ve made breast cancer gene analysis an important part of our genetic health service. As we each come to understand more of the secrets contained in our genetic codes, the prevention, screening and treatment of diseases such as breast cancer will only be more on target.
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This technology, while promising, isn’t likely to change practice yet for most breast cancer patients and their doctors. Over five years, just 23 percent of the women it predicts to be at high risk will actually have their cancer return.