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Genetic Linkage

‘Why did I get cancer?’ We can do more to alleviate ‘angst, guilt’ accompanying a diagnosis

When rocker Tom Petty sang "the waiting is the hardest part," he wasn't referring to genetic testing for breast cancer. But he could have been.

 

After the pathology report from a breast biopsy brings bad news, the next step is often a blood test for risk mutations, probing dozens of genes. Because that information guides the course of treatment, waiting for the findings can send one's stress level through the roof. I've been there.

 

If a mutation is found, removing the unaffected breast suddenly becomes an option, for it may already be on the road to cancer. Alerting children, siblings, cousins, and nieces and nephews to a familial risk may be appropriate.

 

Mutations interfere with natural DNA repair, which allows other mutations to persist that release the normal brakes on cell division. By the time a cancer has been around awhile, the errant cells are riddled with mutations.

 

But mutations in the DNA of white blood cells reflect only the 5 to 10 percent of cancers that are inherited — that is, present in the DNA of every cell of the body and dubbed "germline." The majority of cancers start in body (aka somatic) cells; they don't come in with a sperm or egg, but spring up in cells of the affected body part.

 

Most cancers are genetic but not inherited

 

I'm in several Facebook groups for breast cancer survivors. Every few days, someone posts a variation on "My genetic tests are negative. I have no family history, I'm thin, I do triathlons, I'm vegan and don't smoke or drink. So why do I have breast cancer?"

 

To continue reading, go to Genetic Literacy Project, where this post first appeared.

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