Tags: BRCA | breast cancer | genetic test | Angelina Jolie

Genetic Testing for Breast Cancer

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Wednesday, 03 Aug 2016 04:41 PM Current | Bio | Archive

I am frequently asked by breast cancer patients whether they should undergo genetic testing — specifically testing for BRCA genes.

BRCA1 is a gene on chromosome 17 that normally helps suppress cell growth. BRCA2 is a gene on chromosome 13 that similarly suppresses cell growth.

People who inherit mutations in BRCA1 and 2 have a higher risk of getting breast, ovarian, prostate, and other endocrine cancers. Blood tests can reveal mutations in BRCA1 and 2.

The most famous person to reveal that she was tested for BRCA mutations is the actress Angelina Jolie. When she tested positive, she elected to have a bilateral mastectomy, and later also had her ovaries removed.

Due to the publicity surrounding Jolie’s procedures, many women have clamored to be tested for a BRCA mutation.

BRCA blood tests were first introduced by Myriad Genetics. Somehow, the U.S. government allowed Myriad to own the patent on the two genes that carry BRCA mutations. (How our own genes can be patented is beyond me.)

Because Myriad owned the patent on the genes, for years no other lab could offer BRCA testing. Therefore, Myriad charged an outrageous amount of money — thousands of dollars — to perform BRCA testing.

Now, the U.S. Supreme Court has ruled, unanimously, that human genes cannot be patented. The price of the test has declined to about $1,000 (which is still too expensive).

At first, reports out of Myriad claimed that women with a BRCA mutation had up to a 50 percent chance of developing breast cancer by age 50, and up to a 90 percent chance by age 70. The important part of those claims is the phrase “up to.”

If I knew that a woman had a 90 percent chance of getting breast cancer, I would certainly tell her to consider mastectomy. But it is not that simple.

A March 2015 study looked at the evidence behind the BRCA testing by performing a meta-analysis of 66 relevant studies.11 The authors found that although BRCA1 and BRCA2 mutations had a “ . . . tendency toward a worse breast cancer-specific and overall survival, however, [the] results were heterogeneous and the evidence was judged to be indecisive.”

The authors summarized their findings by writing, “Our review shows that, in contrast to currently held beliefs of many oncologists and despite 66 published studies, it is not yet possible to draw evidence-based conclusions about the association between BRCA1 and/or BRCA2 mutation carriership and breast cancer prognosis.”

If there is a very high rate of breast cancer in a person’s family, then perhaps genetic testing could be warranted. For everyone else, I don’t see the benefit.
 

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Dr-Brownstein
I am frequently asked by breast cancer patients whether they should undergo genetic testing — specifically testing for BRCA genes.
BRCA, breast cancer, genetic test, Angelina Jolie
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2016-41-03
Wednesday, 03 Aug 2016 04:41 PM
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