Welcome @Jezabel. I can't comment on the tnbc but there's a lot of ladies on here who can. I have had a mastectomy on the offending breast and I have to admit to being highly suspicious of the other side. I did start off with a lumpectomy and sentinel node but the surgeon was always clear that, if there was the slightest evidence of a problem, I would need to go back in for further surgery (he did a beautiful job). Well, a supposed 2.5cm tumour was in fact a 4.5cm tumour with no clear margins, and no node involvement became 3 nodes positive so back in I went. In the end, it's your body and your peace of mind but do listen to the surgeon's advice (get a second opinion if you need to) and take it from there.