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Jan 30, 2021 09:53PM
Jan 30, 2021 10:00PM
Martha, I'm sorry that your sister has been diagnosed with breast cancer.
A few things to know before you decide what to do next.
First, most breast cancer, as in 85% or more, is NOT genetic. Genetic breast cancers tend to develop at a younger age; a concern about the possibility of a genetic link to breast cancer usually comes up when the person diagnosed is in her 30s or 40s, or if there is a strong family history.
Second, genetic testing, if it is to be done, is always recommended for the patient first, before any family members. It is more logical to look for a possible genetic mutation in the person who already has cancer. If the patient tests positive, then family members can be tested for the one very specific mutation. If the patient tests negative, then there is no need for family members to be tested. Your sister, being 75, is right at the tail end of the prime years in which the average woman, without a genetic predisposition, is at her highest risk develop breast cancer. So unless there is a strong family history of breast cancer, it is unlikely that genetic testing would recommended for your sister and even less likely that insurance will pay.
Third, genetic testing doesn't necessarily provide a clear "yes" or "no" answer. While there are two well known breast cancer genes, BRCA1 and BRCA2, these days most breast cancer genetic testing involves a full panel of genes - possibly as many as 30 - that all could potentially increase risk of breast cancer by varying amounts. But many of these genes increase the risk of other cancers too. And with that many genes being tested, one possible result is a VUS, a variant of uncertain significance, which means that a mutation was found in the gene, but there isn't enough known yet about this mutation to know if it's harmless (most are) or if it increases risk. So sometimes genetic testing results in more questions than answers.
My suggestion is that you talk to a genetic counsellor before you do anything else. Given the age at which your sister has developed breast cancer, the likelihood that her cancer is genetic is probably very low, which would mean that her diagnosis is unlikely to increase your risk by much. That's not to say that you might not also develop breast cancer, as any woman could, particularly during the highest risk years from 60 - mid/late 70s.
If there is a lot of breast cancer in your family, or other related cancers (ovarian and prostate in particular), that would perhaps suggest a greater likelihood that your sister's cancer might be genetic. This is where a discussion with a genetic counsellor will be helpful.
As for my experience, I was diagnosed at 49. My mother was diagnosed just before me at age 80 but one of her sisters had been diagnosed in her late 40s, so that raised a bit of a red flag. According to my genetic counsellor, the bigger concern was all the prostate cancer on my father's side of the family. I had BRCA testing twice and tested negative both times; new mutations continue to be discovered so testing again after a few years is recommended for those with a strong family history who test negative. I had a panel test of another 20 or so genes. All negative. And I participated in a clinical trial in which I was tested for over 150 cancer genes; of those, I had one VUS for a gene that is very weakly linked to a condition that does increase breast cancer and prostate cancer risk - but the link with this gene is so weak that even if I'd tested positive, no additional screening or any other action would have been recommended. So, lots of cancer in my direct family, lots of genes tested, no answers, no action taken.
Dx 9/15/2005 Right, 7cm+, DCIS-Mi, Stage IA, Gr 3, 0/3 nodes, ER+/PR- ** Dx 01/16/2019 Left, 8mm, IDC, Stage IA, Gr 2, 0/3 nodes, ER+/PR-, HER2- (FISH) ** Surgery 11/30/2005 MX Right, 03/06/2019 MX Left ** Hormonal Therapy 05/2019 Letrozole