Need advice --small margin

I would certainly do what your doctor recommends and depending on what you hear, consider a second opinion.
I would ask the specialists how they explain such a difference between pre-op area and the removed tumor. You need to know nothing was missed. You have an excellent prognosis if it's just DCIS.

Good luck!

Editing to add: your signature says the tumor was 5 cm, however you mentioned above it was only 8 mm. Which one is correct? Also, based on your signature you had reconstruction surgery on both breasts, Is that correct? What kinds of reconstruction and why

Mysticmint, here are the NCCN Guidelines for lumpectomy margins with DCIS:

What they are basically saying is that with DCIS, 2mm margins are required, but if you are having rads and there is only minimal involvement near the margins, well, that might be okay then. To me that doesn't sound overwhelming positive, particularly with grade 3 DCIS. I've been hanging around here long enough to have seen quite a few recurrences after close margins with grade 3 DCIS; many of those recurrences have been invasive cancer, and a few had progressed to mets. That's not to scare you, but from my experience here, I'd say that close margins on grade 3 DCIS is not something to play around with. And the fix is easy. Lots of people have re-excision surgeries; they are usually quick and easy and then the margin concern is eliminated. I also think in your case, because your DCIS is ER-/PR-, you won't be taking endocrine therapy, which reduces recurrence risk by 50%. Without that in your toolbox, it's even more important to ensure that you have adequate surgical margins.

MinusTwo, what's the reason you are suggesting HER2 testing for DCIS? I'm interested in your reasoning and the benefit to Mysticmint, since there are no treatment differences for HER2+ versus HER2- DCIS and since it's unclear whether HER2+ DCIS is any more aggressive or more likely to turn invasive than HER2- DCIS. Interestingly, 40%+ of all DCIS cases are HER2+, versus only 20% of IDC cases - so it wouldn't be surprising for anyone with DCIS to be HER2+. What intrigues me is that if HER2+ DCIS was more aggressive, and if it developed into HER2+ invasive cancer, then logically (and mathematically) one would expect to see a greater percentage of HER2+ IDC cases (50% or 60%, versus the actual 20%). I've been raising these questions about HER2 and DCIS for 15 years now, and we still don't seem to have any better understanding than we did then. Very frustrating.

Minus, I'm positive that if your DCIS was found to be HER2+, you still wouldn't have received chemo. To my understanding, chemo is never given for pure DCIS - or at least hasn't been for the past 20 years at least. First, it's questionable whether chemo works well on DCIS - I know there are studies that have found DCIS remaining in patients who neoadjuvant chemo and who had an otherwise complete pathological response. Second, chemo is a systemic treatment, given to track down and kill off rogue cancer cells that might be in the body. DCIS is a localized diagnosis, with no direct risk of systemic spread. To my understanding, even with invasive cancer, chemo is never given for local mop-up only - it is only prescribed if there is a sufficient risk of mets to warrant the risks from chemo; the localized mop-up is a extra benefit.

As for your recurrence, the location is odd, but on average 1% - 2% of patients who have a MX for DCIS do end up with a localized recurrence, and at least 50% of those recurrences are invasive cancer. NCCN Treatment Guidelines for years (at least since my DCIS-Mi diagnosis in 2005) have recommended no additional treatment after a MX for DCIS. For those who are ER+, endocrine therapy can reduce recurrence risk by 50%, which would mean a maximum benefit of 1% (off a 1% - 2% risk). This benefit is less than the risk of serious side effects. Similarly, chemo can reduce recurrence risk by approx. 30%, so a maximum benefit of 0.6% - again considerably less than the risk of serious side effects. So while the 1% - 2% recurrence risk is real (and is a lot of women, when you think of how many have a MX for DCIS), our currently available treatments don't reduce the recurrence risk enough to outweigh the risks from the treatments themselves. The exception to the "no treatment after a MX for DCIS" guideline is those who have close margins after a MX for DCIS, and possibly those who are BRCA (or other gene) positive, thereby conferring more than the average 1% - 2% recurrence risk after a MX.

Thanks, Minus. After hanging out here and reading up for 15 years, I'm pretty comfortable with DCIS and small invasive cancers - diagnoses similar to my own. I'm also pretty good on the diagnostic process, mostly because I've had breast issues for 48 years and have had so many biopsies and call backs. Rads, chemo, anything beyond Stage I, etc... I know virtually nothing and leave it others like you who are much more knowledgeable. I just know my lane and I stick to it!