To Your Health: When an inherited gene mutation increases breast cancer risk


Women who inherit a harmful mutation in the BRCA1 or the BRCA2 gene are at significantly greater risk of developing breast or ovarian cancers. A genetic test confirms whether a patient has the faulty genes. Photo credit: John A. Burns School of Medicine.

Last year, actor Angelina Jolie made national news when she announced she had undergone preventive surgery to remove both of her breasts.

Jolie has an inherited faulty gene that greatly increased her chances of developing breast cancer. In a piece in the NY Times, Jolie explained:

Only a fraction of breast cancers result from an inherited gene mutation. Those with a defect in BRCA1 have a 65 percent risk of getting it, on average. Once I knew that this was my reality, I decided to be proactive and to minimize the risk as much as I could.

As part of Breast Cancer Awareness Month, we thought it was important to look at two genetic mutations (faulty BRCA1 or BRCA2 genes) that can increase a woman’s risk of breast and ovarian cancer. So we turned to the National Cancer Institute.

Here’s what we found out:

Who’s at risk?

Women who inherit a harmful mutation in the BRCA1 or the BRCA2 gene are at significantly greater risk of developing breast or ovarian cancers.

It’s important to put this in context, though. About 5 to 10 percent of breast cancers are caused by BRCA1 or BRCA2 mutations. Most women who develop breast cancer don’t have these faulty genes.

But experts estimate 55 to 65 percent of women who do inherit a harmful BRCA1 mutation and about 45 percent women who inherit a harmful BRCA2 mutation will develop breast cancer by age 70.

How do I find out if I have these harmful gene mutations?

You can inherit a harmful BRCA1 or BRCA2 mutation from your mother or father. If one of your parents carries the mutation, you have a 50 percent chance of inheriting it.

Certain racial or ethnic groups are more likely to have the faulty gene, including people of Ashkenazi Jewish descent. Those of Norwegian, Dutch or Icelandic ancestry are also at higher risk.

To know for sure whether you carry the mutation, you’ll have to undergo genetic testing. Your DNA will be collected with a blood or saliva sample, and be sent to a lab.

Who should undergo genetic counseling?

Genetic testing for harmful BRCA1 or BRCA2 mutations isn’t recommended for everyone.

Rather, experts say, genetic counseling should be considered as an option when a person’s family history suggests the possible presence of a harmful BRCA1 or BRCA2 mutation.

Doctors use several screening tools to determine if you might be at risk after a family member is diagnosed. For example, they look at whether the family member is younger than 50, has cancer in both breasts, or is of Ashkenazi Jewish ancestry.

If you think you might be at risk, it’s best to talk to your doctor and review your options closely.

For more information on BRCA1 or BRCA2 mutations and breast cancer, go to the National Cancer Institute at the National Institutes of Health.

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