Post-mastectomy boost

[deleted4401]

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Where I did residency, basically everyone got a scar boost. But, I just looked up the guidelines, and it says +/- and doesn't give a clear cut answer on who should got one. It's not quite like intact breast, where we know that most recurrences are within 1 cm of the tumor bed and so there is logic (and data) on the boost.

Excluding inflammatory, who do you guys boost? Is there data on scar recurrences with or without boost (okay, I'm being a little lazy, but I'm sure one of you has it)? Is there people that you definitely don't do a boost on - perhaps T3N0?

-S

 

[Palex80]

We only do a boost for close/positive margins.
We don't boost inflammatory disease as a default.

General prescription is 50/2 Gy in our clinic.


I am not aware of any prospective studies looking into boost for postmastectomy patients, although this would surely be an interesting question.

 

[TarHeelRadOnc]

Where I did residency, basically everyone got a scar boost. But, I just looked up the guidelines, and it says +/- and doesn't give a clear cut answer on who should got one. It's not quite like intact breast, where we know that most recurrences are within 1 cm of the tumor bed and so there is logic (and data) on the boost.

Excluding inflammatory, who do you guys boost? Is there data on scar recurrences with or without boost (okay, I'm being a little lazy, but I'm sure one of you has it)? Is there people that you definitely don't do a boost on - perhaps T3N0?

-S

Definitely no prospective data supporting scar boost.
There are retrospective data showing increased rate of telangiectasia and poor cosmetic outcome with scar boost, but no LRC benefit. One retrospective study shows benefit of scar boost for patients with positive margins or margin width <2mm.

Agree with Palex that 50/2 is standard. I use boost for inflammatory (without data) and close/positive margins only

 

[Brim]

I give a boost to everyone. No, I don't have data to back up this practice, but everyone else is doing it, so hey, why not? (note: "hey, why not?" is not a good boards answer.)

 

[TarHeelRadOnc]

Where I did residency, basically everyone got a scar boost. But, I just looked up the guidelines, and it says +/- and doesn't give a clear cut answer on who should got one. It's not quite like intact breast, where we know that most recurrences are within 1 cm of the tumor bed and so there is logic (and data) on the boost.

Excluding inflammatory, who do you guys boost? Is there data on scar recurrences with or without boost (okay, I'm being a little lazy, but I'm sure one of you has it)? Is there people that you definitely don't do a boost on - perhaps T3N0?

-S

Postmastectomy radiotherapy: patterns of recurrence and long-term disease control using electrons.
Feigenberg SJ, Price Mendenhall N, Benda RK, Morris CG.
Int J Radiat Oncol Biol Phys. 2003 Jul 1;56(3):716-25.PMID: 12788177

Multivariate analyses of locoregional recurrences and skin complications after postmastectomy radiotherapy using electrons or photons.
Huang EY, Chen HC, Sun LM, Fang FM, Hsu HC, Hsiung CY, Huang YJ, Wang CY, Wang CJ.
Int J Radiat Oncol Biol Phys. 2006 Aug 1;65(5):1389-96.PMID: 16863925

 

[Palex80]

A couple of remarks:

1. We do use a (usually 5mm thick) flap through the entire treatment course.
Only in cases of °III acute skin toxicity do we take the flap off for the last sessions.

2. I know of clinics that choose to omit flaps in fear of excessive skin toxicity.

3. 90% of our postmastectomy patients are treated purely with photon tangents.
10% have a mix of tangents and electrons or IMRT (usually cases of unusual convexity of chest wall with prohibitive lung/heart DVHs using standard tangents).

4. I know of clinics that do 54/2 rather than 50/2 Gy.

 

[deleted4401]

Hmm... One of my partners does a 5mm bolus (I think that is the US translation of flap?) daily. I do it every other day. I also think I've seen every day until brisk reaction - around 20 Gy usual (?)

I do 50.4 Gy/28 to CW b/c I do the SCV in 45/25 fx ... But, I guess I could do 50/25 fx and 44/22 fx for the SCV.

Okay, so I'm going to hold off on the boosts...

-S

 

[TarHeelRadOnc]

Hmm... One of my partners does a 5mm bolus (I think that is the US translation of flap?) daily. I do it every other day. I also think I've seen every day until brisk reaction - around 20 Gy usual (?)

I do 50.4 Gy/28 to CW b/c I do the SCV in 45/25 fx ... But, I guess I could do 50/25 fx and 44/22 fx for the SCV.

Okay, so I'm going to hold off on the boosts...

-S

Demonstrating that much of the bolus issue is voodoo anyway, I do 5mm bolus up to 40Gy and d/c for last 5 fx. Similar to you Simul, I treat SCV/level III axilla to 46Gy/23.

 

[Palex80]

1. Yep. Bolus = Flap.

2. We usually give 46/2 to the SCV too.

3. One argument that could be raised in favor of omitting the boost would be the increased prescription of chemotherapy in these patients, especially in the neoadjuvant setting. Inflammatory breast cancer was a pure disaster before neoadjuvant chemotherapy became the standard for these patients.
As far as I know there is a prospective trial active (I am not sure where) looking into hyperfractionated radiotherapy given together with chemotherapy in the neoadjuvant setting for inflammatory breast cancer.

 

[Gfunk6]

Here, we are trained to do 25 fx to 50 Gy. We treat half the fractions with bolus and half without without bolus. Also to verify skin dose we use optical diodes without bolus and film with bolus.

One problem we have is that Pinnacle is not very good at estimating skin dose so our physicists end up using Monte Carlo calculations.

 

[medgator]

Great discussion here. Making me re-examine exactly which of my patients should actually get a boost after PMRT. What cutoff do you guys like to use for "close" margins?

 

[TarHeelRadOnc]

Great discussion here. Making me re-examine exactly which of my patients should actually get a boost after PMRT. What cutoff do you guys like to use for "close" margins?

<2mm. Several definitions exist in literature, but the 2mm cutoff seems to be the most common and reproducibly significant definition in both the post-mastectomy and intact breast settings.

 

[medgator]

<2mm. Several definitions exist in literature, but the 2mm cutoff seems to be the most common and reproducibly significant definition in both the post-mastectomy and intact breast settings.

Yeah I've seen it all over the place. 1 cm (the goal used in the DCIS and invasive CA trials from Mass General that tried to omit XRT) all the way down to 2 mm.

 

[Palex80]

Cutoff for "close" margin in our clinic is <3mm.
We use the 3mm cutoff as well to define boost dose after BCS (10 vs. 16 Gy).

 

[TarHeelRadOnc]

Yeah I've seen it all over the place. 1 cm (the goal used in the DCIS and invasive CA trials from Mass General that tried to omit XRT) all the way down to 2 mm.

1cm margin width has been shown to be a predictor of IBTR in patients not receiving RT. Several DCIS studies, and a couple of studies of invasive breast cancer, have attempted to use margin width of >1cm as selection criteria for omitting RT (... and, with the exception of the oft vilified Van Nuys retrospective study, these trials have almost uniformly failed to identify a group of patients in whom whole breast RT can be safely omitted!).

In patients receiving adjuvant RT, margin width <2-3mm is a predictor of local recurrence, and therefore can be used to select patients for futher dose escalation using a boost. Would not use 1cm width to select for boost in patients already receiving RT, as this margin width has not been shown to be predictive of Local recurrence after surgery + RT.

 

[miamiradonc]

Funny you should ask this question

I am presenting a poster at ASTRO that gives some answers. I was able to retrospectively compare a median 10 Gy boost vs no boost in 600 patients treated with post mastectomy radiation. There were 44 patients with no boost vs 556 with a boost. There was a LRR, PFS, and OS benefit to the boost which withstood multivariate analysis. It is poster number 2002 at the meeting, so drop by Simuld.

BTW we conclude that a prospective randomized trial is warranted and to consider boost in patients with high risk features, node positive, inflammatory, triple neg etc. We only boost at our institution now.

 

[Palex80]

Funny you should ask this question

I am presenting a poster at ASTRO that gives some answers. I was able to retrospectively compare a median 10 Gy boost vs no boost in 600 patients treated with post mastectomy radiation. There were 44 patients with no boost vs 556 with a boost. There was a LRR, PFS, and OS benefit to the boost which withstood multivariate analysis. It is poster number 2002 at the meeting, so drop by Simuld.

BTW we conclude that a prospective randomized trial is warranted and to consider boost in patients with high risk features, node positive, inflammatory, triple neg etc. We only boost at our institution now.

Those are two quite inbalanced groups in terms of size.
556 vs. 44!
I smell heavy bias here, sorry.

 

[medgator]

Those are two quite inbalanced groups in terms of size.
556 vs. 44!

such is the case with retrospective reviews.

 

[Palex80]

such is the case with retrospective reviews.

That's why it's better to do match-pair-analysis in such cases. However with only 44 pairs you are bound not to get a valid, statistical-significant result.

 

[miamiradonc]

Those are two quite inbalanced groups in terms of size.
556 vs. 44!
I smell heavy bias here, sorry.

That is why I only have a poster!

 

[deleted4401]

Certainly hard to make any judgement based on those numbers, but its interesting anyway. One would assume that there would be bias to skip the boost on favorable patients and add it to unfavorable.

A poster is a poster ... If you're a resident, it bought you a trip to San Diego, so good for you!

-S

 

[Palex80]

That is why I only have a poster!

Sure and it's good to look into things like that.
Perhaps there should indeed be a trial looking into this matter.
There are randomized boost trials in breast, why not in chest wall too?

The statistics would be more difficult and you would probably a need larger number of patients to show the difference, since there will be a higher competing risk of systemic recurrence, but it's still doable if a large study group does it.

The only problem is, that it's a "too" radiooncological trial, looking into a very straight-forward question. These are the trials that should be done, but today noone is willing to allocate resources for trials like that. Everyone is excited about small molecules / antibodies and new drugs.
Noone asks the questions that really matter.

Why don't you try to talk with people visiting your poster in ASTRO and see if you can find a clinic where boost is not given as a standard? Maybe you can launch a joint effort making matched-pair analysis of your patients with those of the other clinic where boost is not standard. Come up with 500 pairs and you have an excellent retrospective study, which has the potential to get published in a highly-rated journal.

 

[miamiradonc]

I think that they do not boost at MSKCC and at Dartmouth they do not boost. There are actually a substantial number of centers that do not boost. Thanks for your advice.

 

[Gfunk6]

. Everyone is excited about small molecules / antibodies and new drugs. Noone asks the questions that really matter.

Interesting perspective. However, I think it is an important point and rings true especially in the US.

 

[qwert]

Interesting discussion.
Regarding bolus with tangents. I'm curious, does anybody else do bolus based on perceived skin recurrence risk (i.e. treat with bolus if inflammatory, +skin on path, close ant. margin; no bolus if none of the above)?

 

[Areion]

Funny you should ask this question

I am presenting a poster at ASTRO that gives some answers. I was able to retrospectively compare a median 10 Gy boost vs no boost in 600 patients treated with post mastectomy radiation. There were 44 patients with no boost vs 556 with a boost. There was a LRR, PFS, and OS benefit to the boost which withstood multivariate analysis. It is poster number 2002 at the meeting, so drop by Simuld.

BTW we conclude that a prospective randomized trial is warranted and to consider boost in patients with high risk features, node positive, inflammatory, triple neg etc. We only boost at our institution now.

Hey, did you ever publish these data? Still a very interesting topic!

 

[Cancerdancer]

He did...
PMID: 21514739

 

[BraggPeak]

If a patient has a positive deep margin (DCIS), are you all doing a scar boost? Do you assume that the scar + margin covers the positive margin area?

Also, would any of you treat a SCV for a patient with a T2 N0 (0/9 axillary LNs), triple-negative, s/p mastectomy based on the fact that MA.20 (I know it was not post-mastectomy) included node-negative, triple negative patients?

 

[ShirleyT]

if a patient has a positive margin, i really push the surgeon to re-excise. If not possible, i review the imaging and tumor location, discuss with surgeon the location, and make a generous scar boost, but also incorporate the area of the tumor bed with generous margin as well.

i don't think i would treat SCV or chest wall in a patient with T2 N0 breast cancer, even though triple negative. I understand these patients are at higher risk of failure so there is some rationale, but too scared to go against NCCN guidelines in my private practice.

 

[BraggPeak]

if a patient has a positive margin, i really push the surgeon to re-excise. If not possible, i review the imaging and tumor location, discuss with surgeon the location, and make a generous scar boost, but also incorporate the area of the tumor bed with generous margin as well.

i don't think i would treat SCV or chest wall in a patient with T2 N0 breast cancer, even though triple negative. I understand these patients are at higher risk of failure so there is some rationale, but too scared to go against NCCN guidelines in my private practice.

The z11 trial and MA.20 trials have created more confusion than anything....

I would not routinely treat SCV either in a T2 N0 triple negative s/p mastectomy, but I hear this (and related issues) come up more and more in tumor board in light of the MA.20 trial (which I hear is being published in NEJM in the near future). Was just curious to hear what other SDN gurus are doing....

 

[Palex80]

...but I hear this (and related issues) come up more and more in tumor board in light of the MA.20 trial (which I hear is being published in NEJM in the near future)...

If they are going to publish it in the NEJM it's going to be practice changing.

 

[deleted4401]

Not to be a conspiracy nut, but I'm loathe to believe that NEJM would publish anything indicating radiation or a new radiation technique shows a benefit. NEJM/Nytimes/N Korea are the axis of evil as far as radiation oncology is concerned.

Agree with ShirleyT. There is a rationale, but limited data for a simple community doc to go against NCCN.

S

 

[Palex80]

Not to be a conspiracy nut, but I'm loathe to believe that NEJM would publish anything indicating radiation or a new radiation technique shows a benefit. NEJM/Nytimes/N Korea are the axis of evil as far as radiation oncology is concerned.

They would never publish a negative trial on radiation oncology target volumes in NEJM, would they?

 

[medgator]

Not to be a conspiracy nut, but I'm loathe to believe that NEJM would publish anything indicating radiation or a new radiation technique shows a benefit. NEJM/Nytimes/N Korea are the axis of evil as far as radiation oncology is concerned.

Agree with ShirleyT. There is a rationale, but limited data for a simple community doc to go against NCCN.

S

Nejm seems to have a fetish for sclc, just like jama has a thing for prostate CA

 

[BraggPeak]

This has been coming up more and more where I am at (large academic center). I have been offering PMRT to the CW and nodes in some T2N0 based on LVSI/grade/er negativity based on MA-20, Truong data (Int J Radiat Oncol Biol Phys. 2005 May 1;62(1):175-82.) and paper out of the JCO (J Clin Oncol. 2011 Jul 20;29(21):2852-8) suggesting higher rates of LRR in T1-2N0 triple negative treated with mastectomy alone. I advise my patients that its not the standard of care per NCCN but that there is data supporting the potential incrased risk of LRR based on the pathologic factors they have.

Sorry, I should have clarified-- i was referred to a patient with TNBC, T2 N0, s/p MRM, with positive margin, not a candidate for re-excision ("I was down to the muscle"). So if you have to treat CW, why not add on a SCV? SCV doesn't really add on much toxicity in my opinion...