Invasive Lobular Breast Cancer & CHEK2 gene mutation

Hi, I am Gloria 55 and I have been diagnosed with Invasive Lobular Cancer -22mm. Estrogen Positive, HER-negative, one lymph node taken out and showed negative. According to Oncologist I was borderline to be considered Chemotherapy. Prosigna test was done and showed "medium" risk of reoccurrence. It was left for me to decide if I would like chemo. I investigate more to learn about Mammaprint test which came recently as "High" … again very borderline but "high" 0.006%. My tumour was Luminal. I also volunteered with local research scientists who found CHEK2 mutation. I have done some research to understand that Lobular Cancer does not respond very well to chemo and that survival rates of those who undergo chemo are worse that for those who did not.

In addition to all this, CHEK 2 genetic mutatio means that I donot have two copies of the gene that repairs DNA and am more prone to Cancers. So I assume that chemo needs to be targeted and personalised... rather than blanket approach. Is anybody on this forum able to provide more informationon/experinace on chemo options please? Thank you very much !