MammoPrint for Triple Positive?

I've just been diagnosed with 6mm IDC out of a DCIS diagnosis, came back ER+, PR+ and HER2+. Had re-excision lumpectomy today 4/1 after margins weren't clean from original lumpectomy 3/22. Surgeon also did SNB. He told me this morning he talked with the oncologist after sending her a note that I would like Oncotype or Mammoprint (Know I'm only eligible for MammoPrint due to HER2+ status), and that she told him with HER2+ she didn't want to do that testing. I go see her 4/18.

My questions for y'all are, did you have MammoPrint (or there may be another test like this I'm not aware of)? Did it make any difference? From what I understand it just tells you the likelihood of chemo working for you? I wonder if the Oncologist knows she's going to recommend chemo no matter what and the Mammoprint may just "muddy the waters?" I'll definitely be asking her on the 18th, but wanted to see if anyone has any experience with this.

I know everyone is different. My IDC is only 6mm. Can you take the HER2+ drugs (like Herceptin and Perjeta) without chemo or is that a given or is there a chance I can go back to my DCIS plan of lumpectomy, radiation, and tamoxifen?

Sorry for the rambling questions. (may still be coming off of anesthesia a bit ) I'm a planner and doer. I just want to get this moving. If I need to push her now to send off for Mammoprint so we can have the results on the 18th, I will do it. I like to have all the info I can, and I'm ready to move this process along.

I'm sorry you are going through this. I had a very similar diagnosis but my tumour was 8mm- so a tiny bit bigger. I also had DCIS in the margins.

My medical oncologist said anything about 5mm and Her2 positive should get chemotherapy- but I think out of 10 people who receive the chemo- only 1-2 will actually have a benefit bc 8 of them likely would have been cured with just the other treatment. The hard part really is…..are you one of the two? And honestly they just don't know.

If I were older when I was diagnosed (in 60's) I prob would have been more likely to roll the dice- but being late 30's when diagnosed I went for it all.

I’m in Canada but it wasn’t a choice for me.They did not waste time or money on the test for me. I did not get mammoprint/oncotype bc their recommendations stayed the same.

I'm sorry you are going through this. It sucks, but the twelve weeks of taxol (which they will recommended) went by really quickly. I chose to start taxol knowing I could always choose to stop the taxol and continue on with Herceptin if I wasn't tolerating it. I didn't have to stop and completed the 12 weeks. There is a very informative thread on here about 12 weeks of taxol.

I don't want to sway you either which way. Just some points to consider

I inadvertently had Mammaprint done on a biopsy sample from my 2.6cm tumor because my oncological breast surgeon was participating in a study with Agendia, so my biopsy sample was automatically sent. I had a larger tumor so chemo was a given, the genomic information from Mammaprint that was usable was a definitive narrowing of my subtype. I have been on this site since 2011 and have never seen anyone have genomic testing on a known Her2+ tumor. Rather I have seen discussion about benefit of systemic treatment for very small Her2+ tumors between oncologists and patients based on all of the clinical features for them as individuals. Her2+ patients have a tendency to have a high likelihood of recurrence result on Mammaprint, or any other genomic testing, so it is not routinely done. The NCCN guidelines, and ASCO recommendations, are pretty finite on Her2+ tumors over 5mm - chemo and targeted therapies dependent on tumor size above that threshold. Under 5mm the recommendation is that chemo and targeted therapy should be "considered", but I don't think genomic testing is going to necessarily provide you with actionable information about benefit. The other aspect to consider is that Mammaprint is an expensive test - several thousand dollars. Since you are Her2+ insurance may not cover it, since it is not a standard test to do in this instance. As to your question about the combination of chemo and targeted therapy, the general rule is that chemo is included unless you have co-morbidities that prevent use. The thought is that the chemotherapeutic agents and targeted therapies work better in concert due to synergistic interaction. I have seen very few here that have had targeted therapy alone. For very small tumors the Taxol and Herceptin regimen tested in the APT trial at Dana Farber is very effective and has been well studied. The single agent chemo is thought to be easier to tolerate but effective on small tumors. Here are links about the study at Dana Farber that looked at this, and the subsequent retrospective look at effectiveness beyond five years. You always have the option to decide to forego chemo and Herceptin, but due your due diligence and ask your oncologist to fully explain risk/benefit of all choices.

https://www.breastcancer.org/research-news/20140207-4

https://www.dana-farber.org/newsroom/news-releases/2015/combined-therapy-can-reduce-chance-of-recurrence-in-women-with-small--her2--breast-tumors--study-shows/

https://pubmed.ncbi.nlm.nih.gov/30939096/