"I was 62 when diagnosed with stage I breast cancer earlier this year. Because my mother and her sister had both developed breast cancer (after menopause) and because I'm Ashkenazi Jewish on that side of the family, my breast surgeon referred me for genetic testing, a move seconded by my gynecologist -- both women.
"I'll digress briefly here to mention that there was a definite gender divide on this matter: my male primary care physician had discouraged me from genetic testing when I asked him about it during my annual physical a few months before my diagnosis, saying it was more useful for younger women, and my male oncologist felt likewise. Similarly, the same PCP and my male shrink commented that DCIS is overtreated in the US and that I probably didn't need a lumpectomy for it. Maybe so, but it was during the pre-lumpectomy MRI that my invasive cancer was found, missed by the mammo that caught the DCIS. So I'm glad I went with the advice of my female surgeon, and also glad that I heeded advice that I've found on this site.
"The testing was entirely paid for by my health insurance, or I might not have bothered. It consisted of meeting for two hours with a pair of genetic counselors who helped compile a sort of morbid family tree, followed by my giving a blood sample to be tested for the BRCA1 and 2 mutations and twenty-one other possible genetic traits.
"I ended up testing negative for the BRCA mutations, so I'll hang on to my ovaries for the time being. But interestingly, the counselors felt there's a strong possibility that Lynch syndrome may run in my family, based on our history, which includes lots of cancers on both sides. If you're unfamiliar with Lynch syndrome, as I was, here's some information about it: http://ghr.nlm.nih.gov/condition/lynch-syndrome. (I myself tested negative for it, fortunately.)
"Their recommendations: continue to be screened regularly for colorectal cancer (I'm one of the unlucky souls who gets these tests every three years rather than every ten). And I don't have any kids, but the counselors felt I should advise my nephews, the sons of my late brother whom we lost to glioblastoma several years ago, to obtain baseline colonoscopies now, while they're in their twenties and thirties, and to have them perhaps every five years.
"So I would say that there are definite benefits to genetic testing, although not always the ones you expect. I found it all quite interesting and I recommend it widely."
-- Larkspur, tested negative for genetic mutations