difficult case in breast

[Kroll2013]

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Dear colleagues,

your opinion is much appreciated.

35 years old patient with a family history of breast cancer.
She palpated a lump in fer right Breast.
Bilateral breast mammogram was done, followed by an MRI and a petscan.
All imaging modalities showed a highly suspicious mass of the upper inner quadrant of the right breast of 5cm with multiple right axillary nodes and right internal mammary pet + nodes, as well as positive left axillary nodes with no obvious malignancy of the left breast.
Biopsies of the right breast mass, bilateral axillary nodes confirmed cT2N3 right breast Ca with left axillary mets, ER/PR +, Her2 negative.
She received me-adjuvant chemotherapy.
Control MRI significant decrease in the size of the right mass with complete nodal response.
She underwent bilateral breast mastectomy and axillary LND
Pathology:
Right: high grade IDC , 2.5 cm residual timor, DCIS +++, negative margins, 0/7 LNs, ypT2ypN0
Left: no tumor detected, 0/15 LNs, ypTypN0
She was referred for adjuvant radiation therapy. I will give her IMRT, 25 fractions to the right chest wall and regional nodes.
What would you cover on the left side ? Only axillary? All RNI? Would you give left CW? Or nothing ( wide ALND)?

 

[Palex80]

It would be interesting to know how many nodes were involved according to the initial scan on both sides.
I would be reluctant to treat the left axilla, since she has had 15 nodes removed there without any residual disease and I would definetely not treat the left chest wall.
7 nodes removed on the right side are not awful many.

Thus, my guess would be:
Right chest wall, right axilla, right supraclavicular fossa, right internal mammary chain, left supraclavicular fossa.
Irradiation of the left supraclavicular fossa is highly debatable in my opinion. Left internal mammary chain may also be an option, considering that the spread to the left side may have come through that. RT would however increase heart and lung dose substantially.

 

[Bequerel]

Given her young age and the fact that you had medial drainage of primary to IMN’s, I would give her the benefit of doubt that this was a locally-regionally advanced presentation and not true stage 4 disease and I would treat her with definitive intent. You get one shot at it, so why not treat b/l chest wall and b/l regional nodes with IMRT. If she is alive to worry about late cardiac toxicity, then you did an excellent job. Besides, with a good IMRT plan you can minimize risks. It should be a considerably better plan then she would have received 10-15 years ago.

 

[Radiator20]

It sounds like the left axilla was biopsied and was felt to be involved with the same tumor, not a second primary. If so, she had distant mets. I think one could still consider being locoregionally aggressive but it is important to keep this context in mind. You could consider PET restaging to be sure she hasn't developed a new met elsewhere since surgery.

 

[Radiator20]

Thinking about this some more, the left axillary dissection was really a metastectomy. I can’t think of any situation where I’d give adjuvant RT to the site of a metastectomy with negative margins. Thus, I think the left axillary met was adequately treated by surgery and there is no role for adjuvant RT to left axilla. There is also clearly no reason for left CW RT given no disease in left breast. You could go chasing elective nodal volumes across midline (left IM, left SCV, etc), but she could just as easily fail in the low neck which you aren’t treating, so I wouldn’t.

So, if she is interested in aggressive locoregional therapy despite metastatic disease (which does seem reasonable given young age), I would consider comprehensive right-sided PMRT to CW plus full regional nodes, but I wouldn’t treat anything on the left. I still think repeat PET may be a good idea. You don’t specify what neoadjuvant chemo she got, but I would see whether med onc has any inclination for additional adjuvant chemo, given her high distant met risk, in addition of couse to adjuvant endocrine tx.

 

[anonymuncule]

out of curiosity... which technique(s) do most people here use to irradiate IMC? wide tangents? electrons? VMAT? etc

 

[Palex80]

out of curiosity... which technique(s) do most people here use to irradiate IMC? wide tangents? electrons? VMAT? etc

VMAT. We even barely use 3D for breast/chest-wall.

 

[medgator]

VMAT. We even barely use 3D for breast/chest-wall.

I've ended up seeing worst heart (and even lung) dose with some vmat plans compared to 3D/FinF or e-comp ... I guess it's case by case

 

[RO2019]

Same. For most cases I don't think IMRT buys you anything for breast plans. If anything it seems to cost - both in real life money and dosimetric parameters. Curious if people are finding better plans with IMRT?

 

[scarbrtj]

Same. For most cases I don't think IMRT buys you anything for breast plans. If anything it seems to cost - both in real life money and dosimetric parameters. Curious if people are finding better plans with IMRT?

Which form of IMRT, CPT 77385 or 77386? Intensity modulation will always decrease the inhomogeneity versus non-IMRT (level 1 evidence).

 

[Haybrant]

Thinking about this some more, the left axillary dissection was really a metastectomy. I can’t think of any situation where I’d give adjuvant RT to the site of a metastectomy with negative margins. Thus, I think the left axillary met was adequately treated by surgery and there is no role for adjuvant RT to left axilla. There is also clearly no reason for left CW RT given no disease in left breast. You could go chasing elective nodal volumes across midline (left IM, left SCV, etc), but she could just as easily fail in the low neck which you aren’t treating, so I wouldn’t.

So, if she is interested in aggressive locoregional therapy despite metastatic disease (which does seem reasonable given young age), I would consider comprehensive right-sided PMRT to CW plus full regional nodes, but I wouldn’t treat anything on the left. I still think repeat PET may be a good idea. You don’t specify what neoadjuvant chemo she got, but I would see whether med onc has any inclination for additional adjuvant chemo, given her high distant met risk, in addition of couse to adjuvant endocrine tx.

Wait what; the right breast met’d to the left axilla w no other distant disease? Sounds very med onc of you. That is a second primary with no lesion in the left breast.

 

[RO2019]

Which form of IMRT, CPT 77385 or 77386? Intensity modulation will always decrease the inhomogeneity versus non-IMRT (level 1 evidence).

Not talking about field in field 3D conformal.

 

[medgator]

Which form of IMRT, CPT 77385 or 77386? Intensity modulation will always decrease the inhomogeneity versus non-IMRT (level 1 evidence).

Did you mean to ignore 77301?

 

[Radiator20]

Wait what; the right breast met’d to the left axilla w no other distant disease? Sounds very med onc of you. That is a second primary with no lesion in the left breast.

That's the information OP gave us. And that's why the first thing I wrote was about clarifying that point. Because it obviously does make a significant difference, but I think we have to put significant weight in the pathologists' judgement on whether or not they're the same tumor. Also, a contralateral breast primary remaining occult after MRI and mastectomy is possible but not particularly likely.

Biopsies of the right breast mass, bilateral axillary nodes confirmed cT2N3 right breast Ca with left axillary mets

It sounds like the left axilla was biopsied and was felt to be involved with the same tumor, not a second primary

 

[medgator]

. Also, a contralateral breast primary remaining occult after MRI and mastectomy is possible but not particularly likely.

Nor is a solitary met to the contralateral axilla

 

[Radiator20]

Nor is a solitary met to the contralateral axilla

I agree with you a priori, but this does have to be one or the other. And the only real data we have to clarify in this specific case is histology and receptor status, so again, I think important to weigh that info.

If you thought this were a second primary, what if anything would you treat on the left given 0/15 LN on ALND and a cT0/ypT0 breast?

 

[evilbooyaa]

VMAT. We even barely use 3D for breast/chest-wall.

What? What are your mean heart doses with VMAT? Every VMAT plan I've seen for breast has a mean heart dose > 10-14 Gy which I think is outrageous for a Rad Onc to accept given the Darby data, especially in a 35 year old. Why are you using VMAT for routine breast/chest-wall??

IMRT in breast treatment planning if done routinely should be 'sliding window', basically infinite field in field, not VMAT. We've discussed on this forum previously whether sliding window that is justified in billing IMRT - my care is more for what the patient receives, not what it's billed as.

This patient has oligometastatic disease. I've seen one or two cases of this exact presentation. Bulky ipsilateral axillary lymph nodes, isolated contralateral axillary metastasis. I'm not buying synchronous primaries (especially if receptors are equal).

I would, at minimum, treat R CW + RNIs (including R IMNs).

I would have discussion with patient (given young age) and med-onc - If goal is to be maximally aggressive could entertain treating L CW + RNI, but it certainly isn't mandatory. Agree with the point that radiating a metastatectomy with negative margins isn't routine. Probably wouldn't chase IMNs. I, personally, would not treat RNI alone without CW - I would rather patient get no RT in that scenario.

If I was treating bilaterally I would treat with basically 3-field on each side, with DIBH for both sides, try to have a 1cm gap in tangential fields.

out of curiosity... which technique(s) do most people here use to irradiate IMC? wide tangents? electrons? VMAT? etc

Usually we do wide tangents. If unacceptable dosimetry (rare) we do electron-photon matching. Sometimes we do DIBH for R-sided tumors to inflate lung volume and lower ipsilateral lung V20.

 

[scarbrtj]

Not talking about field in field 3D conformal.

Right, breast IMRT.

 

[Palex80]

I've ended up seeing worst heart (and even lung) dose with some vmat plans compared to 3D/FinF or e-comp ... I guess it's case by case

Depends on your arc arrangement. Full rotations certainly lead in many cases to worse heart/lung doses. We mostly use partial arcs (around 40° rotation each) coming in from the typical angles the tangents would come from.

What? What are your mean heart doses with VMAT? Every VMAT plan I've seen for breast has a mean heart dose > 10-14 Gy which I think is outrageous for a Rad Onc to accept given the Darby data, especially in a 35 year old. Why are you using VMAT for routine breast/chest-wall??

I can show you tons of VMAT plans for left side breast with very low mean heart doses. It all depends on what one defines as VMAT.


Here's one:

Mean dose to the heart is 0.9 Gy

 

[emt409]

Depends on your arc arrangement. Full rotations certainly lead in many cases to worse heart/lung doses. We mostly use partial arcs (around 40° rotation each) coming in from the typical angles the tangents would come from.


I can show you tons of VMAT plans for left side breast with very low mean heart doses. It all depends on what one defines as VMAT.


Here's one:

Mean dose to the heart is 0.9 Gy

Got SS of a VMAT plan covering IM's? Or do you use an electron patch? Been trying to convince our department to adopt VMAT for breast..

 

[Palex80]

Got SS of a VMAT plan covering IM's? Or do you use an electron patch? Been trying to convince our department to adopt VMAT for breast..

Partial arcs will not work well when trying to cover IM nodes.

 

[emt409]

Partial arcs will not work well when trying to cover IM nodes.

This has been my experience as well. And success in matching an electron patch to a VMAT plan has so far eluded me. Aria will not let you co-optimize with mix between VMAT and electron - if it did, I think the process would work.

 

[evilbooyaa]

I can show you tons of VMAT plans for left side breast with very low mean heart doses. It all depends on what one defines as VMAT.


Here's one:

Mean dose to the heart is 0.9 Gy

.... You are missing significant amounts of breast tissue laterally with the picture you have sent. This is whole breast and not PBI? What's the rationale for using VMAT over tangents in that patient? That patient has anatomy to be treated just fine with tangents. If heterogeneity is an issue then do FiF and if your dosimetrists aren't able to do that then do sliding window IMRT. Which line is the V20 Gy line? Appears to be bowing more into the lung potentially more than a half-beam block with tangents would.

What if it's a chest-wall patient? What about with regional nodal irradiation? The cases that VMAT is argued for normally is for IMN coverage... what's the mean heart dose on the second plan using full arcs? Look at the contralateral breast dose and increased lung dose with full arc VMAT in that second picture! Again, which line is the V20 line? Your contralateral breast and lung dose would be lower with either wide tangents or electron-photon matching. I don't mean to be antagonistic just for the sake of it but showing me a low mean heart dose on what is essentially a tangents only WBI using very small partial arcs and then ignoring the dosimetric inferiority in the subsequent full arc plan is something I'm just not understanding.

 

[Palex80]

.... You are missing significant amounts of breast tissue laterally with the picture you have sent.

I disagree. The "significant amounts of breast tissue" you are referring to is the axilla.
You can see the countours of the CTV for the breast, it is well covered by the 95% isodose.

This is whole breast and not PBI?

Yes, whole breast.

What's the rationale for using VMAT over tangents in that patient? That patient has anatomy to be treated just fine with tangents. If heterogeneity is an issue then do FiF and if your dosimetrists aren't able to do that then do sliding window IMRT.

Our dosimetrists can do all of that and regulary do that. We don't do VMAT as "single option", we evaluate plans and techniques. In this case, dose outside the PTV, target coverage and dose homogenity were better with VMAT.

Which line is the V20 Gy line? Appears to be bowing more into the lung potentially more than a half-beam block with tangents would.

Perhaps, but a conformal RT would also lead to a higher dose strip directly under the breast. VMAT bulges there too (the other way around). What's worse? A bigger strip of 20 Gy or a bigger strip of 45 Gy?

What if it's a chest-wall patient?

We will evaluate, but VMAT is certainly an option and done in many (if not most) cases. I hate electrons for chest wall RT.

What about with regional nodal irradiation? The cases that VMAT is argued for normally is for IMN coverage... what's the mean heart dose on the second plan using full arcs?

It's 3.1 Gy. The IM-RT leads to that. I have never seen a plan with IM-RT (with any technique, protons excluded) that will actually deliver a low dose to the heart.

Look at the contralateral breast dose and ncreased lung dose with full arc VMAT in that second picture!

Indeed, higher than with 3D, but:
a) the patient is older than 75 years of age --> contralateral breast is irrelevant
b) conformal RT would lead to higher volumes of high-dose exposure to normal tissues

Again, which line is the V20 line?

Your contralateral breast and lung dose would be lower with either wide tangents or electron-photon matching.

Welcome to the 80s!

I don't mean to be antagonistic just for the sake of it but showing me a low mean heart dose on what is essentially a tangents only WBI using very small partial arcs and then ignoring the dosimetric inferiority in the subsequent full arc plan is something I'm just not understanding.

Your argument does not make sense.
I was discussing 2 things.

1. Partial arcs are great in my experience for doing breast only RT (you can use them for breast + axilla too, but they won't work well for IM-RT or SCF-RT). They are at least comparable to tangents, I have never actually seen a plan, where they were worse than tangents. The dose homogenity is generally better and you avoid excessive dose to the axilla.

2. Full arcs are great for comprehensive nodal RT. You can skip all the field matching with electrons-photons and avoid excessive high-dose to OARs.

You are mixing up these two arguments.

 

[RO2019]

welcome to the 80s?

feel bad for you (and your patients) that you don't know how to do good 3D breast planning. your dosimetry sucks.

Do better for your patients.

 

[Palex80]

welcome to the 80s?

feel bad for you (and your patients) that you don't know how to do good 3D breast planning. your dosimetry sucks.

Do better for your patients.

Wow, thank you for this wonderful comment.

Electron/photon matching is a technique that was developed in the 2D-era. I should have probably said "Welcome to the 60s". I do not see any benefit by using such a technique nowadays.

Do not expect any more replies from me on this thread, the quality of the debate has deteriorated and I am not willing to continue arguing at this level. I am done.

 

[emt409]

Wow, thank you for this wonderful comment.

Electron/photon matching is a technique that was developed in the 2D-era. I should have probably said "Welcome to the 60s". I do not see any benefit by using such a technique nowadays.

Do not expect any more replies from me on this thread, the quality of the debate has deteriorated and I am not willing to continue arguing at this level. I am done.

We have this argument in new patient conference all the time. Some attending in their 60s is all like, "but in blah blah blah with 2D, they covered blah blah blah," --- yes, that's why I drew a f***ing CTV -- this patient doesn't fit that trial, and I don't want to cover those areas, because granny already has ****ty peripheral vascular return and I don't want granny to get lymphedema.

 

[seper]

IMO, using a planning system to calculate dose at photon-electron junction is inherently inaccurate. Some places don't even do image-based electron planning, period.

 

[Radiator20]

IMO, using a planning system to calculate dose at photon-electron junction is inherently inaccurate.

Certainly electron/photon match plans typically look a mess, but why do you feel that the plan is inherently inaccurate?

 

[seper]

My understanding is that treatment planning systems still do very poor job in electron beam dose calculations.

Certainly electron/photon match plans typically look a mess, but why do you feel that the plan is inherently inaccurate?

 

[Radiator20]

My understanding is that treatment planning systems still do very poor job in electron beam dose calculations.

I can’t speak to all TPS, but Eclipse uses a Monte Carlo model for electron planning, and our physicists tell me it is at least as accurate as the photon dose calcs. Certainly things can still get dicey with very small or highly irregular cutouts, though

 

[evilbooyaa]

welcome to the 80s?

feel bad for you (and your patients) that you don't know how to do good 3D breast planning. your dosimetry sucks.

Do better for your patients.

Let's try to remain professional in our discussions about topics. Act as if they were face-to-face with you and had the ability to swing at you if so desired in regards to the content you put forward.

 

[evilbooyaa]

@Palex80 3.1 Gy MHD for covering R side IMNs isn't completely unreasonable I suppose. Maybe my stance on this is too dogmatic and the people I've seen doing it just aren't caring about the right things.

That being said, wide tangents for R Breast will likely lead to a MHD dose less than that depending on patient anatomy, and generally the V20 line will not be that far into the lung... what was the ipsi V20 for the R-IMN plan? You're also getting low dose spreadout in the remainder of the lung and contralateral lung and breast. Might not be an issue for a 75 year old but would certainly be a concern of mine in a younger patient.

For CW I didn't mean electrons.... we routinely do tangential 3D for CW as well.

I think a bigger strip of 20 Gy in lung is worse than a small hotspot in the breast (which can be further mitigated with FiF or sliding window IMRT), personally.

And yes, welcome to the 80s, where outcomes have been great and continue to be great in terms of locoregional control. Why fix what isn't broken?

 

[thecarbonionangle]

Idk what it is about breast rad oncs. It just attracts some peculiar personalities. Another funny breast argument. Almost rivals the field in field as IMRT locked down thread. You have a disease with generally great outcomes and we have treatments that work and work well. There is not always an absolute right or wrong answer. So much dogma about breast and intellectual masturbation at chart rounds.

Someone took a swing here stating “welcome to the 80s” then got offended when someone swung back. We can all disagree without getting offended all the time. IMO the VMAT plans are inferior than a 3D plan would have been. Is it “unreasonable”? no. Is it necessary? No. Is it significantly better? no. So the “80s” thing was not warranted. Electron photon matching even though you cant model it clinically works. It makes us uncomfortable but if it bothers you that match you shouldnt use electrons as planning systems model them very poorly generally.

Aren’t you in Europe? Doubt VMAT would get approved here on our patients for most cases.

At the end of day, we colleagues here. Its good for me to read about what people think.

 

[Radiator20]

if it bothers you that match you shouldnt use electrons as planning systems model them very poorly generally.

Again, may depend on the TPS, but this is not universally true. Eclipse models them just fine via Monte Carlo.

 

[seper]

Some senior physicists I've worked are OK planning IM electron patches at depth using TPS, but some are dead set against it.

Again, may depend on the TPS, but this is not universally true. Eclipse models them just fine via Monte Carlo.

 

[Radiator20]

Some senior physicists I've worked are OK planning IM electron patches at depth using TPS, but some are dead set against it.

It may well depend on the specific TPS. Also, my point was about how accurately Eclipse TPS models electrons in general--not about whether IM photon/electron matches look good from a dosimetric perspective. (In my experience, they don't, even when accurately modeled).

 

[Palex80]

@Palex80
That being said, wide tangents for R Breast will likely lead to a MHD dose less than that depending on patient anatomy, and generally the V20 line will not be that far into the lung... what was the ipsi V20 for the R-IMN plan? You're also getting low dose spreadout in the remainder of the lung and contralateral lung and breast. Might not be an issue for a 75 year old but would certainly be a concern of mine in a younger patient.

V20 for right lung was 22%.

I think a bigger strip of 20 Gy in lung is worse than a small hotspot in the breast (which can be further mitigated with FiF or sliding window IMRT), personally.

Indeed, I agree on that. My problem with tangential irradiation of the lymphatics is that the strip of the lung receiving a high dose (mainly >35-40 Gy) is quite large. When trying to cover more lymphatics with tangents, you end up having a bigger lung volume within the tangents.

And yes, welcome to the 80s, where outcomes have been great and continue to be great in terms of locoregional control. Why fix what isn't broken?

Outcomes are not bad with standard techniques. But they could be perhaps better.
You know, outcomes with prostate RT using 3D were not that bad either. We could easily deliver 74-76 gy with conformal 3D with rather low toxicity, yet people pushed for IMRT, raised the dose by a couple of Gy up to 80 Gy (which is what most of us probably do, if not hypofractionating) and lowered side effects. But the improvement was not huge. No clear OS benefit, a small PFS benefit and a small improvement in side effects. Yet, people did it. Why was that?

At the end of the day it's all the same question: What is worse? Irradiation of small parts of normal tissue/OARs with a high dose or Irradiation of large parts of normal tissue/OARs with a low dose?
This is probably not an answer which is clear as white or black, but some sort of grey. The good part about modern techniques is that you choose while level of grey you want to have, by choosing angles, setting constraints, etc.
You cannot do that this well with 3D-techniques which are based on 2D-treatments basically.
I myself am not convinced that an ipsilateral lung V10 at 40% & V40 at 10% (which you may end up getting with an IMRT plan) are worse than a V10 at 30% & V40 at 15% (which you may end up getting with a 3D plan).
I just made the numbers up, but I hope you understand what I am trying to point out.

 

[Palex80]

My understanding is that treatment planning systems still do very poor job in electron beam dose calculations.

Especially when air is involved, which is the case with the lungs.
I have heard several physicists pointing out that we do not really know how to model electrons' behaviour when they reach the end of the chest wall and enter the lung.
Some say lung tissue will absorb them, some say they will keep on flying until they hit something solid.

 

[Palex80]

Someone took a swing here stating “welcome to the 80s” then got offended when someone swung back. We can all disagree without getting offended all the time.

You may want to read the wording again.

Aren’t you in Europe? Doubt VMAT would get approved here on our patients for most cases.

Well, that's a US problem and frankly I believe that the harsh limitations on what you are allowed to do with IMRT/VMAT in the US are a direct consequence of regulations in the US allowing to charge IMRT for alot more money than 3D.
This led to a dramatic rise in IMRT specifically for prostate cancer treatments in the US, driving costs high. Was it justified? I will let you answer that.
Had this development never happened in the US in the late 90s/early 00s (?) would have also meant that things like Urorads would have never emerged.
So, when you ask the insurance company if you could do IMRT/VMAT for a stage III NSCLC case and your request gets rejected, question yourself what went wrong there.

We only get a small "bonus" for planning with IMRT/VMAT. 3D and IMRT/VMAT treatment delivery (money per fraction) is the same amount.
Where I work right now this tratment planning "bonus" for VMAT/IMRT is couple of thousand dollars more in comparison to 3D. And if your 3D planning is complex (like field-in-field techniques), the difference will be even smaller.

 

[scarbrtj]

Aria will not let you co-optimize with mix between VMAT and electron - if it did, I think the process would work.

It does. It's labor-intensive though. My process reminds me of integration by parts from calculus days. If you plan an electron to full dose and try to use that as a base dose plan for IMRT or VMAT optimization (you can!), it comes out a bit sucky if you try to abut them or overlap them. However, if you plan at 1/x Rx dose, and then do another plan with completely different angles and approaches at 1/x dose, and then another at 1/x dose, kind of modifying along the way each time... then finally summing all this together using calc with preset (MU) values... you can get quite nice plans. Here, simplest approach is x=2. Sometimes I do x=3. At x=4 it's even better but can take a couple days. Just depends on how anal (see below) you wanna be.

Whether to "believe" electron 3D TPSs, that is an argument I leave to others. (I believe it.) ICRU 71 says electrons should be planned as 3D, versus simply prescribed to an IDL, when possible (ie define CTVs, PTVs, etc), and that modern TPSs accurately model (ie Mote Carlo) 3D electron dose distributions.

@Palex80, opinions are like anuses--everyobody's got one, unless you've survived a low-lying rectal CA. I think your WBI plan looks no better than IMRT tangents. Your IMN plan looks pretty good. A mixed γ/e plan can look very good but I bet VMAT is easier to plan, perhaps easier to clinically reproduce too.

 

[KHE88]

IMRT tangents.

A whole lot of WTF in this thread.

I have been trained to treat intact breast and chestwall almost exclusively with 3D conformal tangents using field-in-field and deep inspiration breath hold technique. IMNs are almost always included when treating comprehensive RNI and DIBH typically allows acceptable coverage with tangents, but occasionally will require an electron patch. Rates of unacceptable OAR doses with 3D tangents + DIBH have been reported lower than with IMRT:

https://www.thegreenjournal.com/article/S0167-8140(17)32742-1/pdf
https://www.practicalradonc.org/article/S1879-8500(16)30230-2/abstract.

"Real" reverse-planned IMRT/VMAT (not just simple tissue compensation with an extra blocked field) results in occasionally better coverage at the expense of higher mean heat dose and lung V5 and V20.
There is an additional concern with difficulty immobilizing breast/reproducibility, which is obviously a problem with IMRT, so that improved coverage might not really be there.

The bottom line is that you meet target and OAR constraints 99% of the time with good planning. There are certainly special cases involving weird IMN situations such as bilateral PMRT with bilateral involved IMNs or weird implant/reconstruction situations.

I would refer anyone still confused about what IMRT means back to this article, both in the American rad onc vernacular and when it comes to billing, which seems to be quickly forgotten: Breast intensity modulated radiation therapy versus tissue compensation: what's in a name? - PubMed - NCBI

I have been beating my head all throughout residency at how overly complicated we make breast treatment and bicker back and forth about it. DIBH + 3D tangents for virtually everything. Electron patch for IMC if you have to. IMRT in very unique cases when you cannot meet constraints and clinically can afford some extra heart and lung dose. Done.

 

[scarbrtj]

A whole lot of WTF in this thread.

I have been trained to treat intact breast and chestwall almost exclusively with 3D conformal tangents using field-in-field and deep inspiration breath hold technique. IMNs are almost always included when treating comprehensive RNI and DIBH typically allows acceptable coverage with tangents, but occasionally will require an electron patch. Rates of unacceptable OAR doses with 3D tangents + DIBH have been reported lower than with IMRT:

https://www.thegreenjournal.com/article/S0167-8140(17)32742-1/pdf
https://www.practicalradonc.org/article/S1879-8500(16)30230-2/abstract.

"Real" reverse-planned IMRT/VMAT (not just simple tissue compensation with an extra blocked field) results in occasionally better coverage at the expense of higher mean heat dose and lung V5 and V20.
There is an additional concern with difficulty immobilizing breast/reproducibility, which is obviously a problem with IMRT, so that improved coverage might not really be there.

The bottom line is that you meet target and OAR constraints 99% of the time with good planning. There are certainly special cases involving weird IMN situations such as bilateral PMRT with bilateral involved IMNs or weird implant/reconstruction situations.

I would refer anyone still confused about what IMRT means back to this article, both in the American rad onc vernacular and when it comes to billing, which seems to be quickly forgotten: Breast intensity modulated radiation therapy versus tissue compensation: what's in a name? - PubMed - NCBI

I have been beating my head all throughout residency at how overly complicated we make breast treatment and bicker back and forth about it. DIBH + 3D tangents for virtually everything. Electron patch for IMC if you have to. IMRT in very unique cases when you cannot meet constraints and clinically can afford some extra heart and lung dose. Done.

yeah, like Larry says, they call it iMRT, but if thou speakest that phrase thou chargest much money. Be that as it may, it’s IMRT. If that violates folks’ delicate sensibilities, so be it. Write a letter to the editor; tell ‘em they’ve made a mistake.

 

[KHE88]

yeah, like Larry says, they call it iMRT, but if thou speakest that phrase thou chargest much money. Be that as it may, it’s IMRT. If that violates folks’ delicate sensibilities, so be it. Write a letter to the editor; tell ‘em they’ve made a mistake.

When you put a physical wedge in the field, you are technically "modulating" the intensity of the beam. This does not mean you should call it IMRT. When that acronym is used it means something different, and we all know this.

Not to get into this too deep again, but what exactly is the point you are trying to make by intentionally and repeatedly mislabeling 3D conformal breast plans with field in field tissue compensation as "IMRT" and linking to old obscure studies from other countries in the early days when IMRT was a new term as a way to somehow justify that it is the correct way of referring to things now?

If you are billing the former as the latter, you are committing fraud IMO. I'm not saying this is what you're doing, or this is why you keep arguing that field-in-field 3DCRT should be called IMRT, but I'm having trouble following your objection to this. Is it just semantics? Are you just pontificating about how it's a less than accurate term? If so, I agree, and can we just move on and accept that IMRT doesn't practically mean what it precisely means by the strictest definition? If you want to start a campaign to rename things, fine. But lets come up with a new name for inverse planned IMRT rather than trying to rename FiF 3D as IMRT. Because the latter effort leaves you with two very different planning techniques both called "IMRT." Why on earth would you want that given the way things are billed? "IMRT tangents?" Really? Are you just trying to be edgy?

 

[scarbrtj]

but I'm having trouble following your objection to this.

Just going with the preponderance of the literature, and the CMS definitions. Heretical? So be it. "Old, obscure... from other countries..." Haha. That's a good one. From other countries?! That's craaaaazy!

 

[Palex80]

I have been trained to treat intact breast and chestwall almost exclusively with 3D conformal tangents using field-in-field and deep inspiration breath hold technique. IMNs are almost always included when treating comprehensive RNI and DIBH typically allows acceptable coverage with tangents, but occasionally will require an electron patch.

Would you care to share a screenshot,where you covered IMNs using only tangents?
Most of the times I faced underdosage in the deeper parts of the IMNs or too much lung tissue in the high-dose region.

 

[KHE88]

Would you care to share a screenshot,where you covered IMNs using only tangents?
Most of the times I faced underdosage in the deeper parts of the IMNs or too much lung tissue in the high-dose region.

I'm still a resident, so I'm not comfortable putting up screenshots of my attendings' patients, but I will say that I have been trained to define my PTV volume as a psuedo PTV that is not expanded into the lung, and I have been trained to accept lower coverage of the IMNs: (D90 > 80% acceptable). My IMC covers the first three intercostal spaces only. This is the way it is done on recent protocols.

If someone wants to make an argument as to why the recent protocols are too lax and I'm doing it wrong, I am all ears.

I would guess you are expanding the IMN PTV into the lung and trying to meet more stringent coverage criteria.

Are you doing DIBH? How much of the IMC are you covering?

 

[Palex80]

I'm still a resident, so I'm not comfortable putting up screenshots of my attendings' patients, but I will say that I have been trained to define my PTV volume as a psuedo PTV that is not expanded into the lung, and I have been trained to accept lower coverage of the IMNs: (D90 > 80% acceptable). My IMC covers the first three intercostal spaces only. This is the way it is done on recent protocols.
If someone wants to make an argument as to why the recent protocols are too lax and I'm doing it wrong, I am all ears.

I am all ears too.
My main concern is that we are indicating IMN-RT based on evidence produced by MA20 and the EORTC trial, which irradiated with very "generous" field arrangements, but are allowing underdosing at the same time. Will the (small) benefit shown in these trials still materialize?

I would guess you are expanding the IMN PTV into the lung and trying to meet more stringent coverage criteria.

Indeed.

That's how its defined in a large trial we currently have running (over 1600 patients to be recruited):

CTV-IMN (internal mammary nodes):
This volume connects cranially to the CTV-"medial supraclavicular nodes" and includes include both the internal mammary
vein and artery with a 5 mm margin. Dorsal border is the pleura. Caudally this volume ends at the cranial side of the fourth rib,
in case of caudal/medial located tumor at the cranial side of the fifth rib.
For the planning target volume (PTV) an additional margin is to be added to the respective CTV in
order to take intra-fraction, inter-fraction motion and machine uncertainty into account.
These margins depend on institutional standards. Generally, the minimum of 5 mm CTV-to-PTV
expansion is recommended.
For planning reasons the PTV should be cropped 2-3 mm beneath the skin in case of breast
conserving surgery and 2 mm beneath the skin in case of post-mastectomy radiotherapy. In case
of skin involvement the ventral border expands to the skin surface.

Are you doing DIBH?

Yes we are.

 

[SneakyBooger]

What was the original question?

Oh yeah, I would treat bilat chest wall/SCV/Right IMN's.

Would anyone use hypofractionation?

 

[BobbyHeenan]

I'll side rail this again....

I too agree with comments that both 3D and IMRT are reasonable approaches for PMRT. I enroll (or at least try to, I'm about 1 out of 10 now on trying to enroll) on NSABP b-51 which does allow IMRT. I'm not an academic breast rad onc, just a community guy that cares and has a handful of NRG/RTOG/NSABP trials open 🙂

I trained never doing IMRT for chest wall. However, in my experience I have found that for some left sided cases if I have a very compliant patient I can get better partial arc VMAT or IMRT breath hold plans than I can with matched electrons/photons (especially patients that have a deep distance to their IM nodes). I can get gate-triggered imaging to confirm appropriate breath-hold alignment and some patients can have a "spotlight" CBCT that rotates quickly around them while they hold their breath as well for more confirmatory alignment.

There is now some clinical data suggesting DIBH IMRT may have a cardiac sparing effect over that of 3D. It's not exactly robust, but it's something....

Of course the low dose lung spill is worse with VMAT/IMRT. Obviously every case is different, but I think if you're comfortable with your VMAT set up there may be a role for it.