Positive Posterior Margin in Mastectomy specimen

[evilbooyaa]

So, long story short, had a patient who had low-risk early stage breast cancer clinically, underwent mastectomy + SLNB, saw one positive lymph node, and did ALND. pT1bN1a, with a positive posterior margin (at ink of mastectomy specimen, not within 2mm or anything). Received adjuvant chemo and now there was discussion of whether PMRT was indicated (patient had immediate implant based recon before positive posterior margin was known)

The surgeon said that a positive posterior margin doesn't count, as the fascia is always taken (at least here) and corresponds to an anatomic boundary; therefore, patient would not need PMRT.

Has anyone heard of something like this before? People usually balk at a close 1-2mm margin, and we had multiple people saying that a positive margin can be ignored in this setting because it's on the posterior aspect of the mastectomy specimen?

@Winged Scapula - Would like your input on this as well!

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[Gfunk6]

The surgeon's statement (in my view) is only valid for DCIS s/p mastectomy. In that specific instance of positive focal margin, there is therapeutic equipoise on PMRT.

However, we are dealing with cancer which, by definition, pisses all over anatomic boundaries. Therefore I would endorse chest wall only XRT; it may not be possible to anatomically localize the boost.

 

[seper]

If the fascia was indeed taken, and margin is still positive, pathologist can review slides and confirm that tumor grew through fascia. If that is the case, treat.


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[evilbooyaa]

Based off the discussion at tumor board, I don't know if the fascia was sent for pathological sectioning. Wasn't included in the path report at least. I'll try reaching out to the pathologist who read it to see if he can provide some clarity.

They made it sound like fascia would not be well visualized on pathology slides - any semblance of truth to that (or know a Pathologist on SDN that could shed some light)

 

[dpmd]

Eh, i would guess they aren't completely denuding the muscle fibers of the pec so i would be inclined to have a positive margin treated (wouldn't re operate) Not sure why they think the pathologist wouldn't be able to tell what is fascia unless they aren't truly getting the fascial later but just the tissue in the nice dissection plane just above the fascia where most surgeons i have worked with stay.

 

[Winged Scapula]

So, long story short, had a patient who had low-risk early stage breast cancer clinically, underwent mastectomy + SLNB, saw one positive lymph node, and did ALND. pT1bN1a, with a positive posterior margin (at ink of mastectomy specimen, not within 2mm or anything). Received adjuvant chemo and now there was discussion of whether PMRT was indicated (patient had immediate implant based recon before positive posterior margin was known)

The surgeon said that a positive posterior margin doesn't count, as the fascia is always taken (at least here) and corresponds to an anatomic boundary; therefore, patient would not need PMRT.

Has anyone heard of something like this before? People usually balk at a close 1-2mm margin, and we had multiple people saying that a positive margin can be ignored in this setting because it's on the posterior aspect of the mastectomy specimen?

@Winged Scapula - Would like your input on this as well!

Interesting you should bring this up because my partners and I were just talking about this with one of our rad oncs.

Classic surgical teaching (at least for my partners and I) is that while a positive posterior margin may not count "surgically" (i.e., we don't go back and you really can't if its focal, after a mastectomy) it is indication for PMRT.

We are trained to take the fascia and see it as a natural anatomical border or limit. I've never had a pathologist comment on "I see the fascia" on a mastectomy specimen. However, like @Gfunk6 notes, cancer ain't following nobodies rules.

What my partners and I were talking with our rad oncs about was whether to go back for a positive deep margin on a lumpectomy when you've gone down to the muscle. They were arguing if muscle wasn't seen on the path specimen, that we need to go back. The surgeons, including myself, were saying that we've never been trained to do that (only to take a piece of muscle if tumor was adherent to it grossly). What say you guys?

 

[Gfunk6]

What my partners and I were talking with our rad oncs about was whether to go back for a positive deep margin on a lumpectomy when you've gone down to the muscle. They were arguing if muscle wasn't seen on the path specimen, that we need to go back. The surgeons, including myself, were saying that we've never been trained to do that (only to take a piece of muscle if tumor was adherent to it grossly). What say you guys?

The problem is localizing the region of positivity. Our breast surgeons leave localization clips after lumpectomy which is greatly appreciated by us as it allows us to target the boost easily. Mastectomy is a different beast; in this particular situation, the patient had an immediate reconstruction which would make it even harder.

Hypothetically though, if you were confident where the margin was and could clear it then I would not recommend PMRT.

 

[evilbooyaa]

Interesting you should bring this up because my partners and I were just talking about this with one of our rad oncs.

Classic surgical teaching (at least for my partners and I) is that while a positive posterior margin may not count "surgically" (i.e., we don't go back and you really can't if its focal, after a mastectomy) it is indication for PMRT.

We are trained to take the fascia and see it as a natural anatomical border or limit. I've never had a pathologist comment on "I see the fascia" on a mastectomy specimen. Like @Gfunk6 notes, cancer ain't following nobodies rules.

What my partners and I were talking with our rad oncs about was whether to go back for a positive deep margin on a lumpectomy when you've gone down to the muscle. They were arguing if muscle wasn't seen on the path specimen, that we need to go back. The surgeons, including myself, were saying that we've never been trained to do that (only to take a piece of muscle if tumor was adherent to it grossly). What say you guys?

Was not at all suggesting re-excision in my case (especially given the immediate implant based recon). Was saying that because of the deep margin, we would suggest radiation. If she didn't have the immediate recon we likely would've gotten her set-up for it without a second thought.

In your case, WS, I'd probably let it go, or at least ask if you'd want to, but I understand that there are those who are very by the book and will push for re-excision on even CLOSE margins (let alone a positive one!)

Just trying to get a sense of the fact whether my 'things-dont-feel-right' detector going off is well-calibrated or not. Obviously can't do much about it as a resident, but good to know I'm not completely on my own in my thought process.

 

[deleted18755]

Thanks so much my friend for creating this thread and please everybody who can contribute chime in ... this is a highly relevant and common clinical scenario for which we have minimal hard data but very strong regional biases so I welcome a thoughtful discussion.

 

[Winged Scapula]

The problem is localizing the region of positivity. Our breast surgeons leave localization clips after lumpectomy which is greatly appreciated by us as it allows us to target the boost easily.

Yep, fairly standard (at least in the fellowship trained breast surgeon); we all leave clips in the tumor bed.

Mastectomy is a different beast; in this particular situation, the patient had an immediate reconstruction which would make it even harder.

Hypothetically though, if you were confident where the margin was and could clear it then I would not recommend PMRT.

I'm not sure how anyone could be confident where the margin was except in the case of grossly visible tumor (in which case I leave a marking clip there, even with mastectomy. But with many women presenting with non-palpable disease, I could only guess the locale based on imaging descriptions of distance from nipple, etc.

 

[Winged Scapula]

Was not at all suggesting re-excision in my case (especially given the immediate implant based recon). Was saying that because of the deep margin, we would suggest radiation. If she didn't have the immediate recon we likely would've gotten her set-up for it without a second thought.

I knew you weren't suggesting re-excision, just that we were talking about reexcising posterior margins with OUR rad oncs last week and the fascial barrier, etc.

I noted that both you and GFunk commented about immediate recon and PMRT. Our local rates of immediate reconstruction are extremely high here. Are yours not?

In your case, WS, I'd probably let it go, or at least ask if you'd want to, but I understand that there are those who are very by the book and will push for re-excision on even CLOSE margins (let alone a positive one!)

True. We were confused because we'd never been asked/challenged about the posterior muscle margin before.

 

[medgator]

Our local rates of immediate reconstruction are extremely high here. Are yours not?

Expanders or do they do implants right away? Would think that's risky if the patient needs PMRT on review of the final path

 

[Winged Scapula]

Expanders or do they do implants right away? Would think that's risky if the patient needs PMRT on review of the final path

As always, depends on a number of factors: whether the patient is a smoker, whether they're definitely going to have PMRT such as in the case of positive nodes preoperatively or large tumor, whether it's a nipple sparing procedure etc.

A lot of plastic surgeons will go straight to implant if all conditions are favorable, but often they are not.

But my question still stands as in the surgical world immediate reconstruction does not mean that it's completed. It's very rare for us not to do it least a tissue expander or direct implant. So when someone says their patients don't get immediate reconstruction I presume nothing is done the time and it's scheduled later.


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[dpmd]

We are trained to take the fascia and see it as a natural anatomical border or limit. I've never had a pathologist comment on "I see the fascia" on a mastectomy specimen. However, like @Gfunk6 notes, cancer ain't following nobodies rules.

If that margin was positive i would expect them to comment on whether cancer is through the fascia or not even if they don't routinely comment on the fascia. At least on second review. I don't remember much from path but i think fascia should be identifiable.

 

[Winged Scapula]

If that margin was positive i would expect them to comment on whether cancer is through the fascia or not even if they don't routinely comment on the fascia. At least on second review. I don't remember much from path but i think fascia should be identifiable.

Yeah, one would think so but I've never seen it done here.

 

[FrostyHammer]

Harvard has studied this:

https://www.ncbi.nlm.nih.gov/pubmed/22975615

 

[Palex80]

1. If the fascia was removed and was not infiltrated, then I don't see a clear indication for PMRT.

2. She is pN1a. Would't you still offer PMRT?

 

[BobbyHeenan]

Harvard has studied this:

https://www.ncbi.nlm.nih.gov/pubmed/22975615

This was for DCIS, where this makes some sense as in if there is not disease breaking through the basement membrane and the vast majority of ductal breast tissue is removed in a mastectomy, then a local failure breaking in through the fascia is very unlikely like this study shows.

We're discussing invasive disease here though, where as mentioned, there is concern that the invasive nature of it would allow it to infiltrate through anatomic barriers like fascia.

====

As an aside, I wish our referring breast surgeons would place clips in lumpectomy procedures. I work with a few very good surg oncs (MDACC and MSKCC trained) and a small handful of other breast surgeons, and the vast majority of time they don't routinely leave clips in spite of my pleas. If there's gross disease or something they're worried about they'll leave clips, but routinely they don't.

 

[DebtRising]

Path should be able to identify the fascia and if there was fascia invasion. It can be difficult in practice from what I am told, because at times surgeons 'scrape' the posterior margin so you can have 1 slide of positive margin at the fascia, and then other multiple slides of connective tissue fibers, which may or may not be able to be oriented well enough to see if they were in vicinity.

If there was invasion of the fascia, which is very rare, then we can use that as an indication for PMRT.

But echoing above, with 1 positive node, there is argument to be made for PMRT based on the EBCTCG meta-analysis (Lancet 2014), with the caveat that the chemotherapy administered was likely inferior in strength to contemporary AC-T regiments (assuming that is what your patient got). And of course there has to be discussion that PMRT has the chance to adversely effect her cosmetic outcome.

Would offer, there is evidence to support clinical benefit in BC mortality, but patient must accept risk of hurting the implant and increased risk of long term lymphedema.

 

[Palex80]

Side question: We have certain surgeons here, that put the implants behind the M. pectoralis.
In these cases CTV ends at the anterior part of the pectoralis muscle, so that the implant itself is not in the CTV.
Do you guys use IMRT for these patients to spare out the implant? We have been doing this for a couple of years now, but I was wondering how the rest of you feel about it.

 

[evilbooyaa]

I knew you weren't suggesting re-excision, just that we were talking about reexcising posterior margins with OUR rad oncs last week and the fascial barrier, etc.

I noted that both you and GFunk commented about immediate recon and PMRT. Our local rates of immediate reconstruction are extremely high here. Are yours not?

Doesn't seem that high at my institution. Obviously I'm biased because we only end up seeing the ones who are considering PMRT (who knows how many patients get mastectomy with immediate recon, don't have a positive margin, and never need a referral to Rad Onc).

We generally see implants, although tissue expanders at times too (which are a pain and make a patient with eventual brain mets be unable to get an MRI). Some patients we see for planned PMRT state they will be foregoing a recon, others state that it'll be after.

If that margin was positive i would expect them to comment on whether cancer is through the fascia or not even if they don't routinely comment on the fascia. At least on second review. I don't remember much from path but i think fascia should be identifiable.

Discussed it with the pathologist, who essentially told me in no uncertain terms, that the margin was called as positive and despite the feeling of the breast surgeon, he can't change the diagnosis. I asked him to see if there was fascia present on the slides, which he did not mention in his reply and seems to have no interest in pursuing. I'm not comfortable pushing too hard as a resident and will be discussing with my attending as well. The brief review by the pathologist at tumor board (not the same person who initially read it out) didn't mention the fascia, but I didn't see anything obvious either, on the one slide that showed the positive margin. Surgeon at tumor board (not the one who performed the surgery) said that fascia doesn't show up well on pathological evaluation. Any truth to that?

1. If the fascia was removed and was not infiltrated, then I don't see a clear indication for PMRT.

2. She is pN1a. Would't you still offer PMRT?

1. I agree.
2. Attending preference to offer it but not highly recommend it in that scenario. Patient would like to forego radiation if at all possible and it seems the surgeon/med-onc/plastic surgeon all agree. Patient did get adjuvant chemo (albeit with CMF x 6)

WS, do you guys take the fascia as part of the mastectomy specimen (like should the fascia be on the inked specimen) or is it mastectomy specimen first followed by removal of fascia afterwards? I feel like it's most likely the former, but not sure.

 

[Winged Scapula]

WS, do you guys take the fascia as part of the mastectomy specimen (like should the fascia be on the inked specimen) or is it mastectomy specimen first followed by removal of fascia afterwards? I feel like it's most likely the former, but not sure.

It comes with the mastectomy specimen; it would be technically very difficult (especially in some where the tissue is very adherent) to remove separately.

 

[FrostyHammer]

Sorry guys for my post above - I gave you the wrong Harvard link.

https://www.ncbi.nlm.nih.gov/pubmed/22543200

 

[evilbooyaa]

I feel like people give chemo in breast cancer for a 4% absolute risk reduction.

Edit: Here are my main takeaways/questions from the article, having gone through all of it:
5-year overall (not just isolated) LRR 8.2% vs 3.1 vs 3.1 (Pos, Close, Neg margins)

Did any of the positive margins have re-resection (especially for a positive superficial margin in a skin-sparing mastectomy?)

Looking at the figure, the 8 to 10-year LRR in positive margins is upwards of 13%, while negative is around 3%

Table 3 - Positive deep margin - 2 of 4 with IDC had LRR. 1 of 9 with DCIS recurred. 16.7% 5-year LRR, vs 3.6% superficial (not significant due to low volume numbers)

27% LRR if positive margin and LVI vs 3% if positive margin w/o LVI

 

[scarbrtj]

Just would like to point out NCCN says "strongly consider" PMRT for 1-3 LN+ patients, which this patient was. So the margin issue here is kind of... marginal? Anyhoo, two strong indications to treat. A more interesting & nerdy question would be: was the sequencing of chemo before the PMRT "best."