There are a few Oncotype tests and more in the pipeline. I'm guessing that you're referring to the OncotypeDX?

Just to remind people, that test has specific parameters and many cancers won't be candidates for the OncotypeDX. Ask your oncology teams for any and all gene or genomics tests that apply to the cancer you're dealing with even the ones possibly not covered by insurance. A friend paid for her OncotypeDX because her insurance didn't cover it but thinks it was a bargain as she avoided chemo and radiation as a result. With her oncologist's concurrence.

It is not my intention to give incorrect information here. I checked my reports and can only tell you my understanding of what my results indicated. My cancer was bilateral, which is uncommon, so that’s already a different category. One breast was DCIS and everywhere, a constellation of cancerous microcalcifations. The other was a micro invasion, IDC. (This was all unexpected because I always had regular screenings.) I had 2 opinions/suppositions prio to the surgery or the pathology and diagnostic tests coming back from the mastectomies and both doctors had already been leaning towards chemo and trying to prepare me. The surgeon that did the mastectomies ordered the Oncotype DX and the pathology report said Ki-67 and FISH to follow. There are other tests that check the same thing as Oncotype, like Mammaprint. She was not optimistic before the results of the Oncotype came in, due to the pathology and it being in both breasts. It came back a early stage, which is important. My Oncotype DX was low so no chemo was recommended. My Ki-67 was 10%. My understanding is that this test determines how quickly the cancer cells replicate. So that low score was another indication that I would not benefit from chemo. I can’t find my results for FISH. Some articles state that Ki-67 is controversial because institutions have different cut off numbers for what “low” means. A “low” number is another indicator of recurrence and survival and the Ki-67 test should not be used alone, but in conjunction with those other tests.
In any case, my invasive cancer was not found in other breast tissue, other than where the tumor was located and they were the same kind of cancer. I had no lymph node involvement. I think everyone involved was surprised but obviously very happy for me.
I did 5 years on anastrozole. At my 5 year check up this summer, my oncologist said he is confident that there will be a reliable blood test soon in order to determine recurrence. For me, that would be amazing because I don’t have anything they can screen. Because my cancer was bilateral among other criteria, I qualified for Genetic Testing to see if I carried the genes for breast cancer. I didn’t, so I was told that it was probably environmental factors. I think they were pretty thorough even though some of the science and correlations are beyond me and fingers crossed that a recurrence is low. I think we all did our best.
Hope for good outcomes!