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Looking for a link: Should you consider genetic testing?

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This article is part of the Cancer Center's News Archive and listed here for historical purposes.
The information and links may no longer be up-to-date.

Visit Genetic Testing for Breast and Ovarian Cancer for up-to-date information

For Rosemary Buck and her daughters Carol and Susan, finding out whether their cancers were genetically related was motivated by more than curiosity. The threat of a genetic link -- and another breast cancer diagnosis -- loomed over the whole family. "After I was diagnosed, Susan decided to undergo genetic testing," says Buck. "She wanted to know if it was by chance or by genes that it struck all three of us. I felt I needed to do it for the rest of the family," Weston says.

Kara Milliron, MS, CGC
Kara Milliron, M.S., C.G.C.

For families with a history of breast cancer, the availability of genetic testing and counseling at major institutions like the U-M Comprehensive Cancer Center offers much-needed guidance.Testing can identify the presence or absence of mutations in two genes,BRCA-1 and BRCA-2 that can lead to the development of both breast and ovarian cancers. "Only 1 in 300 to 1 in 800 people in the general population carry the BRCA-1 or BRCA-2 mutation," says Kara Milliron, M.S., C.G.C., a certified genetic counselor in the Cancer Center's Breast & Ovarian Cancer Risk Evaluation Program. Statistically, about 20,000 women will be diagnosed this year with breast cancer due to an inherited susceptibility.

Some of the predictors that may indicate an inherited susceptibility to cancer in a family include:

  • High numbers of family members with cancer through several generations, on either the mother or father's side.
  • Family members diagnosed with cancer before age 50.
  • Family members diagnosed with multiple cancers.
  • Male breast cancers, or clusterings of certain other cancers.

One tablespoon of blood is all that's needed for the test, but, as Milliron points out, "just because it's simple doesn't mean it's easy. It's the emotional aspects of testing that make it a challenge for families." That's why before any testing, an in-depth counseling session takes place to assess family history and the potential risk of having or passing on the mutation. Counselors like Milliron discuss the risks, benefits and limitations of testing. During this phase, some women may decide they don't want to know whether they carry the mutation. "That's okay," she says. "The right to not know is just as important as the right to know."

Susan Weston's results did not indicate a genetic basis for her cancer. Weighing other factors like the women's age at diagnosis and the lack of other familial cancers, the chances are extremely remote that the genetic defect is present in any other family member. "That leaves us to conclude that this was due to either pure chance, a rare undetectable mutation in BRCA-1 and or BRCA-2 or a mutation in some novel gene yet to be discovered," says Milliron.

Although it did not solve the mystery of why cancer struck three times in Weston's family, genetic counseling can provide unaffected family members with valuable information. Personal risk assessments can be offered which may suggest pursuing additional screenings or chemoprevention.

Milliron confirms that breast cancer occurring in three family members is extremely rare.But she's not surprised that no mutation was found. "The majority of tests come back negative," she explains. "Only 5 to 10 percent of breast cancers can be attributed to inherited susceptibility."

To learn more about genetic counseling for breast and ovarian cancer, visit the Breast & Ovarian Cancer Risk Evaluation Clinic's webpage or call the Cancer AnswerLine™ at 800-865-1125.

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Speak with a Cancer nurse: 1-800-865-1125
Please Note:

This article is part of the Cancer Center's News Archive, and is listed here for historical purposes.

The information and links may no longer be up-to-date.

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