Would you offer SBRT to a paratracheal/paraesophageal lesion?

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RadOnc2013

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Would you offer SBRT to a paratracheal/paraesophageal lesion?
In patients with oligometastatic disease, would you offer SBRT to a metastatic lymph node abutting the trachea and/or esophagus? If so, what dose and dose constraints would you consider? How would you counsel the patient about risk of trachesophageal fistula?

I posted this to theMedNet also, but am unsure how soon they will process this given the holiday.

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I would offer high b.e.d radiation, but I think limiting yourself to 5 fractions for the sake of "stereo" is probably not the best thing to do.
 
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I believe a similar question was addressed fairly recently on Mednet: theMednet - Login

My first thought would be for something like 4 Gy x 15, but I'm no Abe Wu or Greg Videtic.
 
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Depends on the lesion. I'd consider five fraction SBRT if I could get good coverage of at least the GTV at some reasonable dose without violating (or at least strongly considering) TG-101. Before committing to anything I'd have to see the images.

4 Gy x 15 fx is still pretty hot. EQD2/2 is 90 Gy.
 
I've done a couple of these at 7 Gy x 5 or 8 Gy x 5 depending on the site.

So much of it depends on the overall clinical picture and goals of care so hard to make firm recommendations in a vacuum.
 
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I do treat oligometastatic disease aggressively in select cases, but I also acknowledge the benefit is still somewhat nebulous so that makes me very cautious about causing any real toxicity. I like the CALGB study that medgator posted but I doubt many of those tumors were abutting the esophagus so I would do something closer to 26 fractions. I guess some people think bringing in a patient >20 times for non-primary treatment is excess, but I think it depends on the clinical situation and patient resources, etc.

The other option as Gfunk says is SBRT-lite which I have done before too. I like this article because it shows images and surveys a bunch of docs to get a feel for what is considered SBRT-able:
SBRT for centrally localized NSCLC – What is too central?
 
SBRT of central lesions is one of these cautionary tales we tell our children late at night. Back when SBRT was getting en vogue (in the US), I was chit-chatting with a smart academic rad onc from Germany and he was like "We treat these central lesions all the time, 50 Gy in 10 fractions, no problem." It emboldened me to some extent and all these years later I can say: yep, it's not a problem. SBRT has a Medicare definition (5 fractions max!), and a scientific definition. While the former gets almost all the respect and the latter doesn't, 50Gy/10fx is SBRT in my book. It's a book I have to keep to myself however whenever I do 50/10.
 
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SBRT of central lesions is one of these cautionary tales we tell our children late at night. Back when SBRT was getting en vogue (in the US), I was chit-chatting with a smart academic rad onc from Germany and he was like "We treat these central lesions all the time, 50 Gy in 10 fractions, no problem." It emboldened me to some extent and all these years later I can say: yep, it's not a problem. SBRT has a Medicare definition (5 fractions max!), and a scientific definition. While the former gets almost all the respect and the latter doesn't, 50Gy/10fx is SBRT in my book. It's a book I have to keep to myself however whenever I do 50/10.

This is a good point. There are definitely scenarios where I went to 10-15 fractions because it would be safer or more effacious than SBRT-lite. In our current silly reimbursement system, this is defined as IMRT.
 
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This is a good point. There are definitely scenarios where I went to 10-15 fractions because it would be safer or more effacious than SBRT-lite. In our current silly reimbursement system, this is defined as IMRT.
Yup.... Yet another problem awaiting the solution of bundled site neutral payments
 
I think you need to define your goal first.
You are going to allow different constraints for OARs depending on your treatment intention. I personally do not believe that we can cure a lot of those oligometastatic patients. Perhaps we can cure a few but certainly not many.
So in case of paraesophageal lesions, I would do SBRT, but I wouldn't go higher than 10 x 4 Gy to the esophagus. 10 x 4 Gy is probably a rather "safe" dose in terms of late damage if the volume is limited.
I will go higher only if I feel that there's truly curative potential in the treatment.
 
SBRT of central lesions is one of these cautionary tales we tell our children late at night. Back when SBRT was getting en vogue (in the US), I was chit-chatting with a smart academic rad onc from Germany and he was like "We treat these central lesions all the time, 50 Gy in 10 fractions, no problem." It emboldened me to some extent and all these years later I can say: yep, it's not a problem. SBRT has a Medicare definition (5 fractions max!), and a scientific definition. While the former gets almost all the respect and the latter doesn't, 50Gy/10fx is SBRT in my book. It's a book I have to keep to myself however whenever I do 50/10.

That's precisely how we do it. 8 x 7.5 Gy is also quite popular.

One major problem when comparing doses of SBRT is the isodose line people prescribe too. I've seen everything from 60% to 95% isodoses...
 
That's precisely how we do it. 8 x 7.5 Gy is also quite popular.

One major problem when comparing doses of SBRT is the isodose line people prescribe too. I've seen everything from 60% to 95% isodoses...

Also methods of motion management, immobilization, image guidance at time of treatment, PTV size, prescription isodose coverage, organ at risk objectives, etc...

The devil is in the details when it comes to all of this SBRT/SRS.
 
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Assuming it's not invading the trachea or esophagus, I'd lean towards 60/8 for oligomets. MedNet had some constraints posted recently for that fractionation.

50/10 is also a consideration. I wouldn't bring an oligometastatic patient for anything more than 10 fractions.

For a definitive case I'd probably go with 50/5 with close evaluation of dose constraints.

LU-002 does 34/5 for lymph nodes and that could be a consideration as well, accepting non-ablative doses to minimize toxicity in the oligometastatic patient.

Agree that devil is always in the details when evaluating various ways to plan SBRT/SRS... reminds me of a paper where the authors claimed they were delivering 13Gy x 3 to a post-op SRS cavity, then you look at the methods and realize that's the max point dose, which worked out to something like 8-9Gy x 3 prescribed to normal IDLs.
 
The devil is in the details when it comes to all of this SBRT/SRS.
reminds me of a paper where the authors claimed they were delivering 13Gy x 3 to a post-op SRS cavity, then you look at the methods and realize that's the max point dose, which worked out to something like 8-9Gy x 3 prescribed to normal IDLs.
Quixotically, I will forever be saying that when it comes to SRS/SBRT reporting and prescribing, there is a described, agreed-upon method which is straightforward and leaves less room for communication mixups and devilish details. Which is to report the prescribed dose as the minimum absolute Gy dose received by the lesion(s) at a percent isodose ratio of the minimum absolute dose received by the lesion(s) divided by the maximum absolute dose in the plan (which is always set at 100% by convention, and could as an alternative be the max dose inside the lesion instead of the plan when multitargeting); e.g., 8 Gy (times three fractions) at the 62% line in the example given above. It's simple!
 
I believe RTOG for SBRT uses 95% coverage of the PTV by the Rx isodose. If you require 100% coverage you are apt to get very hot plans particularly with lung SBRT. So the minimum dose covering the PTV is less critical so long as 95% gets covered. For cranial SRS 99-100% coverage is reasonable though GTV=PTV or the margins are tight (ie 1 mm).


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I believe RTOG for SBRT uses 95% coverage of the PTV by the Rx isodose. If you require 100% coverage you are apt to get very hot plans particularly with lung SBRT. So the minimum dose covering the PTV is less critical so long as 95% gets covered. For cranial SRS 99-100% coverage is reasonable though GTV=PTV or the margins are tight (ie 1 mm).
This is all well and good but says nothing re: the homogeneity (ie max dose) of the plan. In reality minimal lesional dose planning allows this to be "eyeballed." (We can allow a few underdosed voxels.) When the minimum lesional dose is 95% of the Rx dose using most modern planning systems, ~99% or more of the lesion is getting 99-100% or more of the Rx dose. The "95% thing" is kind of just a quick type-it-in thing to get an agreeable normalization in most TPSs. Furthermore the percentages you mention are again in some fashion ambiguous, or lead to ambiguity. 99-100% of what? An absolute dose? A prescription percent isodose? Maybe. Who knows. With a standardized nomenclature (e.g. 8 Gy to the 62% line), the only room for ambiguity IMHO is: maybe the minimal lesional dose was 7.95 Gy. Or 7.98 Gy. Etc Etc. Again, that this is up for discussion hints at the need for a lingua franca, a standardization of nomenclatures, etc. As I mentioned, this has been done. As can be seen, somehow it hasn't permeated our collective culture. However, re: RTOG, the first SBRT RTOG study read thusly:

... prescription lines covering the PTV will typically be the 60-90% line (rather than 95-100%); however, higher isodoses (hotspots) must be manipulated to occur within the target and not in adjacent normal tissue. The isocenter in stereotactic coordinates will be determined from system fiducials (or directly from the tumor) and translated to the treatment record...The plan should be normalized to a defined point corresponding closely to the center of mass of the PTV (COMPTV). Typically, this point will be the isocenter of the beam rotation; however, it is not a protocol requirement for this point to be the isocenter. Regardless, the point identified as COMPTV must have defined stereotactic coordinates and receive 100% of the normalized dose. Because the beam apertures coincide nearly directly with the edge of the PTV (little or no added margin), the external border of the PTV will be covered by a lower isodose surface than usually used in conventional radiotherapy planning, typically around 80% but ranging from 60-90%... The treatment plan should be normalized such that 100% corresponds to the center of mass of the PTV (COMPTV)... The prescription isodose surface will be chosen such that 95% of the target volume (PTV) is conformally covered by the prescription isodose surface (i.e., 20 Gy per fraction = 60 Gy total), and 99% of the target volume (PTV) receives a minimum of 90% of the prescription dose (i.e., 18 Gy per fraction = 54 Gy total)... The prescription isodose surface selected.. must be ≥ 60% of the dose at the center of mass of the PTV (COMPTV) and ≤ 90% of the dose at the center of mass of the PTV (COMPTV). The COMPTV corresponds to the normalization point (100%) of the plan

By saying "The prescription isodose surface selected.. must be ≥ 60% of the dose at the center of mass of the PTV (COMPTV) and ≤ 90% of the dose at the center of mass of the PTV (COMPTV)," this essentially was a requirement that the max dose in the plan would be between 66.7 and 100 Gy (at a 60 Gy Rx dose). So one can say, "max dose must be 66.7-100 Gy." (This requirement adds a lot of additional information, esp. re: conformity/dose fall-off.) Or, alternatively one could say "the 60-90% isodose line must be prescribed." What has been tradition is the latter versus the former. But just saying "95% of the PTV covered by the Rx dose" is not descriptive enough for SBRT/SRS. The minimal dose covering the PTV *and* the max dose in the plan are critical pieces of info, info which can easily be relayed via an absolute Rx dose at a %IDL naming convention, wherein the max is always 100%.
 
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I am treating one like this to 30Gy/5fx next week. Oligomet patient has a few pop up over the year ultracentrally and this has been well tolerated. I don't know what 60Gy/15fx would do to esophagus, I'd be interested to hear someone else's experience with that dose to a para-esophageal target.
 
A lot of talk about 60/8.
The BED(3) of that is 210. For 50/5 it is 217.
BED(10) is 105 vs 100.
They're basically the same regimens, on normal tissue that's a 3% difference.
RTOG 0813 showed 50/5 centrally is pretty safe. I'm not pushing for that though--I'm pointing out that if you wouldn't do 50/5, don't do 60/8.
It's an easier choice for oligomet--aim has to be not to hurt the patient. 6-8 Gy x 5 or 45-60 in 15 fractions are probably reasonable, as would 50 in 10 fractions (BED3 of 133).
 
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