BRCA Genetic Testing for Women Without a Family History of Breast Cancer

by Dr. Hsien-Hsien Lei
Posted June 20, 2007 in DNA Testing, DNA and Disease

Knowing your family health history is definitely important. But for many of us, that information is lacking. And in some cases, even if you know everything about your family history, it’s not enough. A recent study in JAMA has shown that family structure and size can affect estimates of a woman’s risk of breast cancer.

Imagine you’re a woman whose mother, aunt, and sister all had breast cancer. Chances are, you’d be offered genetic testing for the BRCA1 and BRCA2 mutations, which provides important information for selecting treatments pre- and post-cancer development. Women who carry one of these mutations have an increased risk of breast and ovarian cancer. And, if they already have breast cancer, carriers have an increased risk of subsequent cancer. These women can choose to undergo prophylactic mastectomy and oophorectomy.

Now imagine you’re a woman who does not have a family history of breast cancer. Does that mean your risk of hereditary breast cancer is low? Not necessarily. An estimated 50% of genetic breast cancer is inherited from the father’s side. But if your father comes from single child families or there are few female relatives on his side, there’s no chance to observe breast cancer occurring in family members even if the BRCA mutation has being passed down from generation to generation.

Results from the JAMA study of 306 women diagnosed with breast cancer before age 50 and who did not have a family history:

• 50% had “limited” family structure - fewer than 2 first- or second-degree female relatives surviving beyond age 45 on both sides of the family
• 14% of women with “limited” family structure carried a BRCA mutation compared to 5% of those with “adequate” family structure.
• Those with limited family structures had a 2.8 times greater odds of having the BRCA mutation.

These results suggest that many women who thought they had sporadically occurring breast cancer may actually have cancer associated with inherited BRCA mutation. In an accompanying editorial, Drs. Noah D. Kauff and Kenneth Offit suggest that all women who develop breast cancer before age 50 should be offered a genetic test for BRCA. Under current recommendations, most women with breast cancer but no family history are not offered BRCA testing even though the test could give them valuable information for determining treatment options.

The conclusion? Family history is not enough. Genetic testing should be available to everyone who’s interested in knowing their risk especially if they’re adopted, know little about their family health history, come from small families, and in the case of sex-specific conditions, have few female/male relatives at risk of developing the disease. For those who fear that consumers won’t understand their genetic test results, I believe we should not overlook the opportunity to educate them. Let’s not deny consumers the chance to learn about their own DNA.

NB: I work for DNA Direct, a direct-to-consumer genetic testing company that offers BRCA testing.

Tags: genetic testing, brca, brca1, brca2, breast cancer, genetics, genes, dna, diseases, illness, health, medicine

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7 Comments »

Comment by Brian from babybiotechs.com

2007-06-20 19:50:27

The problem is that the frequency of BRCA1 and BRCA2 mutations are low enough in the general population that it’s probably not economically viable for health insurance companies to test women who aren’t at high risk.

The study says,
“The observed 13.7% rate of mutations in cases with limited family structure exceeds typically applied thresholds for offering genetic testing.”

But the cases already had breast cancer. What we need to know is what percentage of the general population (that have limited family structure) have BRCA1 mutations, which I didn’t see in my scan of the paper. I’d imagine it’s still well below the threshold.

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Comment by Hsien

2007-06-21 09:40:10

Agreed. A general population screening for BRCA wouldn’t be cost effective (at this point in time) and would raise the specter of false positives and negatives (also subject to the limitations of current technology). But offering BRCA testing to women who developed breast cancer before age 50 looks to be a wise choice.

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Comment by Steven Murphy MD

2007-06-21 00:37:10

Hsien,
Now here is something I can get behind. If you have BRCA testing it is clinical valid. We’re not talking Chromosome 9 for MI here. If you have breast cancer and are younger than 50 you should get tested Period….End of story. With this set of genes were are not talking true multifactorial disease. In multifactorial disease the likelihood of having the disease increases with the number of family members afflicted. That is why family history is only somewhat useful in Autosomal Dominant Diseases. But much more Important in multifactorial disease……
Single gene disease is not the same as heart attack or diabetes. To misrepresent that is not the best thing to do…
-Steve
http://www.thegenesherpa.blogspot.com

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Comment by Hsien

2007-06-21 09:48:05

Wow! Really? You could get behind this?

LOL Just teasing you. This is clearly a situation where there’s a pre-existing condition indicating testing rather than a general population screen. Although I still believe we all have the right to information on ourselves if we want it.

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Pingback by Eye On DNA Is Rated R — Eye on DNA

2007-06-22 10:10:51

[...] this is what I get for discussing breast cancer and BRCA genetic testing, drug companies and personalized medicine, and reproduction and sex [...]

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Comment by Sister Study

2007-06-22 21:40:38

How would you like to make a difference in breast cancer research? The Sister Study needs your help to determine if breast cancer is caused by something women come in contact with at work, at home, in their communities or in the personal products they use.

The Sister Study is looking for 50,000 women to help discover the environmental and genetic causes of the disease. Women ages 35 to 74 are eligible to join if their sister (living or deceased), related to them by blood, had breast cancer; they have never had breast cancer themselves; and they live in the United States or Puerto Rico.

ENROLL TODAY or simply help spread the word to women in your community! Either way, you can help find the causes of breast cancer!!

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Pingback by Perceptions of Genetic Testing

2007-07-12 17:25:27

[...] Is medical genetic testing worth the ordeal if there is no cure or 100% effective prevention? From what I’ve observed in discussions online, these are some general attitudes towards genetic testing along with my responses in italics in the context of breast cancer: [...]

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