Why are the genetic test for cancers can only be done to pregnant women??

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I live in Florida and I wana get done a genetic test of cancer and they told me it can only be done to pregnant woman's why???

My mom is having severals cancer currently and I wana now that I am ok

But gynecologist that I call said that does test can only be done to pregnant women and I am not pregnant 😒

Is there any gynecologist around here that can tell me why is that?