3DCRT for PostOp Brain Mets...

[SneakyBooger]

Are we doing the best we can for pts who undergo RT for PostOp brain mets?

Last week was consulted for an inpatient treated at an outside institution adm'd to our hosp whose post op SRS in December 2018 resulted in severe detriment to his QOL due to RT necrosis. He has had a miserable 6+ months since.

Got me to thinkin (rare but possible).

No necrosis in this small trial of 3DCRT...

Postoperative local fractionated radiotherapy for resected single brain metastases - Strahlentherapie und Onkologie

Purpose Evaluation of postoperative fractionated local 3D-conformal radiotherapy (3DRT) of the resection cavity in brain metastases. Patients and methods Between 2011 and 2016, 57 patients underwent resection of a single, previously untreated (37/57, 65%) or recurrent (20/57, 35%) brain...

link.springer.com

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[medgator]

Completely agree. Srs is kinda stupid and oncologically unsound in some post op cases. I've done wbrt in rare situations or fractionated partial brain rt instead.

In addition to radionecrosis, marginal miss is another big concern with post op srs/srt in some cases

 

[xrthopeful]

what fractionated dose do you use? I agree that single fraction SRS not ideal for these post-op cases. I've seen people do fractionated SRS (3-5 fx) but curious of other approaches.

 

[medgator]

what fractionated dose do you use? I agree that single fraction SRS not ideal for these post-op cases. I've seen people do fractionated SRS (3-5 fx) but curious of other approaches.

40/15 3dcrt. Not a ton of data, just something I picked up, although it's pretty much post op primary CNS dosing in Canada or even here nowadays in poorer PS GBM pts.

Or even wbrt dosing would be fine, just don't treat the whole brain

 

[nkmiami]

NYU at one point had series of 40/15. I will often give 5-6 Gy x 5 or 8Gy x 3

 

[Mandelin Rain]

Just today I was thinking of giving up on my typical 2700cGy/3 post-op SRS with 3mm margin. Too many failures vs necrosis.

Glad to see I'm not alone in my anecdotes.

 

[SneakyBooger]

This pt had 8 Gy X3 to 90%, Novalis Trilogy/ExacTrac, not sure what margin was...

 

[scarbrtj]

OoOoH (scary ghost sound)
Voices from the past...
We’ve Got a Treatment, but What’s the Disease? A Brief History of Hypofractionation and its Relationship to Stereotactic Radiosurgery
"Fractionated stereotactic radiosurgery is far more consistent with the principles of conventional radiobiology and oncology and represents the quintessential application of three-dimensional treatment planning. Stereotactic radiosurgery is really stereotactic radiotherapy, and when applied in single fraction to the treatment of cancer, it is suboptimal radiation oncology. Its utilization is virtually predicated on the ability to perform another craniotomy to remove focal necrosis."
Disclaimer: I do plenty of SRS. But one predictor of toxicity in SRS is tx volume; always has been, always will be... resection cavities: usually not small.

This pt had 8 Gy X3 to 90%, Novalis Trilogy/ExacTrac, not sure what margin was...

Wouldn't ordinarily equate this w/ high risk of necrosis. Equivalent to about 54 Gy/27fx (especially given ~110% max inhomogeneity) depending upon one's beliefs etc.

 

[SneakyBooger]

This cavity was only 1.2 cm, so kinda small postop wise...

I would post the pic but kinda scared of the privacy police.

 

[scarbrtj]

This cavity was only 1.2 cm, so kinda small postop wise...

I would post the pic but kinda scared of the privacy police.

That is small. 8 Gy times 3, 90% IDL. And a ~1.2cm target volume. Are we "sure" this is necrosis? He had XRT Dec 2018. It's July 2019; he's been miserable for 6 months. A very unusual timeline for necrosis problems too. I'm sure you're sure, just nothing fits as much as I'd like it to.
EDIT
differential: tumor regrowth, infection, subacute limbic encephalitis as a paraneoplastic syndrome... anything but necrosis heh

 

[SneakyBooger]

He has undergone 4 MRI's since SRS and it doesn't appear to be recurrence. Cavity has small amount of stable enhancement along one edge that has minimally increased in size over those many months - just a tiny bit thicker. Unable to wean from Decadron 4mg QID since SRS either. If it is recurrence, it sure is taking its sweet time.

Primary is NSCLC - I don't recall subtype off top of my head.

You thinking something else?

 

[xrthopeful]

40/15 3dcrt. Not a ton of data, just something I picked up, although it's pretty much post op primary CNS dosing in Canada or even here nowadays in poorer PS GBM pts.

Or even wbrt dosing would be fine, just don't treat the whole brain

makes sense to me

 

[scarbrtj]

He has undergone 4 MRI's since SRS and it doesn't appear to be recurrence. Cavity has small amount of stable enhancement along one edge that has minimally increased in size over those many months - just a tiny bit thicker. Unable to wean from Decadron 4mg QID since SRS either. If it is recurrence, it sure is taking its sweet time.

Primary is NSCLC - I don't recall subtype off top of my head.

You thinking something else?

So his clinical problems are a lot more impressive than his scans... again not my favorite with radionecrosis. I'm sure we all prefer some radiographic findings. MR-SPECT can be done but doubt useful here. Is he on anti-seizure meds? Those have side effects. What are sx's, QOL, why "miserable"? (Being on 16mg of decadron a day can be hard on QOL too in the long run.) Purely clinical radionecrosis without radiographic correlate? IMHO that does technically lower the likelihood of radionecrosis. EDIT: any NSCLC with some "neuroendocrine" element could theoretically increase the probability of subacute limbic encephalitis (probably more NSCLC is histologically mixed than we realize). SLE: a zebra, but a real zebra.

 

[Palex80]

The funny thing about postop SRS is that I have seen people prescribing that dose to the 80% isodose. And I wondered "why"?
Do they think the highest risk for relapse is in the middle of the "hole", also referred to als "resection cavity", which is why they chose to put the highest possible dose there?

 

[Reaganite]

Completely agree. Srs is kinda stupid and oncologically unsound in some post op cases. I've done wbrt in rare situations or fractionated partial brain rt instead.

In addition to radionecrosis, marginal miss is another big concern with post op srs/srt in some cases

I completely agree too! I'm ready to abandon completely. I have seen multiple recurrences after post-op SRS presented in our CNS case conferences. This includes patients treated at 'centers of excellence.' I pulled up a paper a few months ago (forget where) showing very high rates of recurrence (50%-ish) in patients with larger lesions abutting the dura who receive postop SRS.

 

[xrthopeful]

8 x 3 to the 90% IDL to a small target is a fairly reasonble/modest dose IMO.

People get necrosis, I wouldn't blame the radiation dose chosen.

 

[scarbrtj]

The funny thing about postop SRS is that I have seen people prescribing that dose to the 80% isodose. And I wondered "why"?
Do they think the highest risk for relapse is in the middle of the "hole", also referred to als "resection cavity", which is why they chose to put the highest possible dose there?

It doesn't make a hole lot of sense.

 

[Pointless]

I've had good luck thus far with 7-8 Gy x 3 post-op. I reserve 9 Gy x 3 for larger intact brain mets per the Italian data. Haven't seen much necrosis at all.

TBH, my biggest concern with post-op cases has been the development of leptomeningeal disease of which I've seen an unfortunate few.

 

[medgator]

TBH, my biggest concern with post-op cases has been the development of leptomeningeal disease of which I've seen an unfortunate few.

Marginal miss possibly. Again, toxicity and local control issues make me hesitate to do post op srs/set except in the smallest of mets post op.

The move away from wbrt to srs/srt in the post op setting hasn't really been that data driven imo but rather just because of a (sometimes irrational) hatred of wbrt and/or making pts come in for more than 1-5 fx

 

[gmsquid]

I think you can do 25- 30 in 5 to most modest size postop brain volumes. The trick with postop is you have to have more generous volumes that include the likely surgical contamination.

 

[scarbrtj]

The move away from wbrt to srs/srt in the post op setting hasn't really been that data driven imo but rather just because of a (sometimes irrational) hatred of wbrt and/or making pts come in for more than 1-5 fx

Doing more than five fractions or asking "where's the data?" these days is more controversial than saying you should be allowed to play a tree.

 

[medgator]

I think you can do 25- 30 in 5 to most modest size postop brain volumes. The trick with postop is you have to have more generous volumes that include the likely surgical contamination.

The problem is when you get these bigger brain mets with extensive edema pre op and post op. No way I'm giving 5 fx SRT to the whole posterior fossa or half the brain.

Happy to take the fraction shaming there

 

[Palex80]

The problem is when you get these bigger brain mets with extensive edema pre op and post op. No way I'm giving 5 fx SRT to the whole posterior fossa or half the brain.

Happy to take the fraction shaming there

Edema is not CTV, at least not in our practice and nowhere I know of.
We generally only treat the cavity or cavity + any contrast enhanchment in T1 (which can also be postoperative scar / inflammation) as "GTV". Add to that a CTV a 3mm and a 3mm PTV. That's it.
30 Gy in 6 fractions is what we give. I've never seen a necrosis.

 

[xrthopeful]

I also have never heard of including edema

 

[medgator]

Edema is not CTV, at least not in our practice and nowhere I know of.
We generally only treat the cavity or cavity + any contrast enhanchment in T1 (which can also be postoperative scar / inflammation) as "GTV". Add to that a CTV a 3mm and a 3mm PTV. That's it.
30 Gy in 6 fractions is what we give. I've never seen a necrosis.

Yet we do see these recurrences. Maybe that has something to do with it. I don't try to include it, but it makes me nervous nonetheless, esp in the larger lesions so I'm happy let it get encompassed in the ptv

 

[Palex80]

Guidelines were published a while ago. My impression is that most recurrences happen at the edge of the resection cavity, since many people consider cavity = CTV. This is probably too small. You need to include some brain around the cavity within your CTV and you need to account for some CTV-PTV-margin too. That's why we end up with the 6mm around the cavity (3mm CTV- / 3mm PTV-margin).

The recurrences I have seen so far were either in high-dose-volume or meningeal spread. Many have critisized this meningeal spread as a consequence of not doing WBRT, yet this is not proven. At least in some patients it is imagineable that the meningeal spread occured metachronous to the brain radiotherapy. WBRT would not have prevented it. The rest is probably a consequence of the surgical procedure and I imagine that there may be differences in the rates of meningeal spread according to location of metastasis, surgical approach, histology. We still need to learn here.

 

[Pointless]

Agree. We know that leptomeningeal spread can occur with some frequency post-operatively and is likely just a case of contamination during resection. Whether or not WBRT would impact this at all is less clear; I am inclined to believe it probably wouldn't.

In my practice, I include the cavity + rim enhancement and expand to PTV by 2 mm. I also agree with Palex that sometimes 5 x 5 or 6 x 5 is a reasonable alternative for large cavities and I don't think I've ever seen necrosis from 5 fraction treatment. Also handy for intact brainstem mets.

 

[OTN]

6 Gy x 5 with a 2mm margin has worked well for me. I’m a believer in the data I’ve seen suggesting pretty high rates of recurrence and leptomeningeal spread postop.

Additionally, as we’re seeing patients live longer with brain mets, we’re seeing intracranial recurrences that patients never were around long enough to see before. When we give 5 fx to the lung we give 50-55 Gy- would make sense our recurrence rates would be higher in the brain due to necrosis limiting dose, both definitely and postoperatively.

 

[xrthopeful]

6 Gy x 5 with a 2mm margin has worked well for me. I’m a believer in the data I’ve seen suggesting pretty high rates of recurrence and leptomeningeal spread postop.

Additionally, as we’re seeing patients live longer with brain mets, we’re seeing intracranial recurrences that patients never were around long enough to see before. When we give 5 fx to the lung we give 50-55 Gy- would make sense our recurrence rates would be higher in the brain due to necrosis limiting dose, both definitely and postoperatively.

Absolutely agree.

In the immune checkpoint era, with patients living longer, we will see more recurrences, and will also see more patients living long enough to get necrosis.

 

[Neuronix]

He has undergone 4 MRI's since SRS and it doesn't appear to be recurrence. Cavity has small amount of stable enhancement along one edge that has minimally increased in size over those many months - just a tiny bit thicker. Unable to wean from Decadron 4mg QID since SRS either. If it is recurrence, it sure is taking its sweet time.

Wait... Small cavity, small stable enhancement, still on dex 4 mg QID ? Something is odd with that story. Was the initial tumor very large? I would have still expected the edema to have come down. What symptoms do they have and have they seen a neuro-oncologist? Those sorts of doses of dex long-term are pretty toxic.

The correct dose, fractionation, margin, etc is debated significantly for cavities. If you poll the academic CNS people, you will get a lot of different answers to this question.

My thoughts are:
1. 40 Gy in 15 fractions to a focal area of the brain probably is safe. Some are trying to dose escalate that further for glioblastoma (there was a small European trial for this and some are proposing it in larger trials). Whether that's really effective in the brain mets setting, who knows. There is retrospective data for it.

2. Brain mets have always been thought of as a poor prognostic indicator (see survivals from the RPA which I'd argue is outdated), so there has always been a push for shorter courses of therapy. So could you do 10 fractions to 30-35 Gy or even 5 fractions 20 Gy focally? It's probably fine. Control is probably on the order of 15 Gy in 1 fraction for intact mets comparing different trials or series.

3. Stereotactic does pay better than a short 3D course, and even more when fractionated. I don't know how much that really plays into the decision making. Nevertheless, a lot of people feel very comfortable to deliver "stereotactic" courses with regular linac and mask setups and large PTVs to cavities, citing uncertainty about the target. More and more people are doing this for intact mets as well, which makes me nervous given the amount of thought that should go into stereotactic cases (and these used to go more to specialized centers).

4. For cavities with stereotactic alone, phase 3 data is from the MD Anderson trial (Post-operative stereotactic radiosurgery versus observation for completely resected brain metastases: a single-centre, randomised, controlled, phas... - PubMed - NCBI). So I'm more apt to follow that. Their doses were on the lower side IMO--they had no RT necrosis and a high rate of failures for their ranges of doses (12 Gy - 16 Gy in 1 fraction), so I tend to push a little higher. For example, they had 3 protocol deviations for people giving 18 Gy in 1 fraction to small cavities, and I also tend to do this. Edit: I was also reminded of the NCCTG trial AKA RTOG 1270 by KHE88 below which used similar doses with 1 RT necrosis event.

5. Minnitti's data has been impressive for fractionated, especially three fraction. I wonder if it's "too good to be true" in their comparisons to single fraction. To answer the question, there is a cooperative trial coming soon for single fraction vs. fractionated for cavities (3 fraction for small, 5 fraction for large).

6. PTV margin is hotly debated. There is a question of technical accuracy depending on your linac setup and there is a question of subclinical spread. All of these tumors have microscopically positive margins, so you know there is still disease there. I tend to do 1 mm PTV on GK and 2 mm PTV on linac. There is a lot of variability in contouring, so at least we have the consensus paper as a starting point (https://www.sciencedirect.com/science/article/pii/S0360301617339536?via=ihub).

As for doses, I treat 15 - 18 Gy in 1 fraction on GK for most cavities. For large cavities or tumors over 3 cm (or subtotal resection), I consider 30 Gy in 5 fractions on linac. Is this the right dose? Nobody really knows that either. The typical range of doses in 5 fractions is 25 - 35 Gy, with retrospective data you can pull to support any of those. There's also a cooperative group trial in the works on this question as well.

 

[evilbooyaa]

Agree that clinical story does not agree with radiology. Would consider resection of this mass. Being on Dex 4mg QID for 6 month is a bad, bad idea and patient is better served with resection if at all feasible.

I have never done more than 5Fx for intracranial SRT. I am comfortable doing 5Gy x 5 to as big of a post-op cavity as necessary. 2mm PTV margins to cavity at minimum. Plan for less heterogeneity than standard SRS. Would consider 6Gy x 5 but I've seen a couple necrosis cases with that.

I don't know that I would ever feel good about bringing a brain met patient for 3 weeks of treatment.

 

[KHE88]

For those doing fractionated SRT for post-op, are you doing daily treatments or every other day?

The RTOG 1270 protocol lists single fraction treatments even for very large cavity sizes. And I always did single fraction in training but am not super comfortable with it.
I am, for instance, having a hard time deciding between 17 Gy x1 vs. 9 Gy x3, vs 6 Gy x5 for 12cc cavity (20 w/ margin).

Finally, does histology matter? I.e., Do you go 9 Gy x3 vs 8 Gy x3 for melanoma?

 

[Neuronix]

I have never done more than 5Fx for intracranial SRS.

Just on the nomenclature here:
SRS (stereotactic radiosurgery) = 1 fraction brain. Some people use it for single fraction spine (i.e. spine SRS) while others call single fraction spine SBRT or SABR.

FSRT (fractionated stereotactic radiation therapy) = Multi-fraction brain stereotactic. In the USA this implies up to 5 fractions. In other countries (usually Germany), they sometimes refer to IMRT w/ IGRT with PTV margins 3 mm or less as FSRT. This is in part because some international centers use Cyberknife for long course fractionated treatments (e.g. 28 fractions), while we don't usually do this in the USA.

From a billing standpoint, SRS means 1 fraction brain only. Multi-fraction is called SBRT. Anything in the spine, even single fraction, is SBRT.

 

[evilbooyaa]

For those doing fractionated SRT for post-op, are you doing daily treatments or every other day?

The RTOG 1270 protocol lists single fraction treatments even for very large cavity sizes. And I always did single fraction in training but am not super comfortable with it.
I am, for instance, having a hard time deciding between 17 Gy x1 vs. 9 Gy x3, vs 6 Gy x5 for 12cc cavity (20 w/ margin).

Finally, does histology matter? I.e., Do you go 9 Gy x3 vs 8 Gy x3 for melanoma?

3 fractions - every other day
5 fractions - every day

I, personally (no data), think 9Gy x 3 to intact lesions and 8Gy x 3 to post-op lesions is fine.
Similarly for 6Gy x 5 for intact and 5Gy x 5 for post-op (but less confident about this one).

I believe the Minitti data that says single fraction does worse and has more necrosis in large tumors or cavities, even if it's retrospective.

 

[evilbooyaa]

Just on the nomenclature here:
SRS (stereotactic radiosurgery) = 1 fraction brain. Some people use it for single fraction spine (i.e. spine SRS) while others call single fraction spine SBRT or SABR.

FSRT (fractionated stereotactic radiation therapy) = Multi-fraction brain stereotactic. In the USA this implies up to 5 fractions. In other countries (usually Germany), they sometimes refer to IMRT w/ IGRT with PTV margins 3 mm or less as FSRT. This is in part because some international centers use Cyberknife for long course fractionated treatments (e.g. 28 fractions), while we don't usually do this in the USA.

From a billing standpoint, SRS means 1 fraction brain only. Multi-fraction is called SBRT. Anything in the spine, even single fraction, is SBRT.

Scarbrtj levels of pedantism there, Neuronix, lol.

Although noted - I edited my post to say SRT.

Although publications do use the term 'fractionated SRS' not infrequently. There's also SRT, hypofractionated SRT as options for nomenclature.

I do consider everything outside the brain as SBRT, while I imagine some people say everything outside the CNS is SBRT.

 

[Neuronix]

Scarbrtj levels of pedantism there, Neuronix, lol.

Although noted - I edited my post to say SRT.

Maybe. I think it's important to get this stuff right. Sterotactic radiotherapy is a devil is in the details technique.

 

[xrthopeful]

I don't think there is necessarily a 'right' here though?

If you ask some people, SRS means single fraction
If you ask some people, SRS means in the CNS
If you ask some people, SRS means in the CNS AND Single fraction.

Also - didn't Minniti do 3 fx three days in a row?

 

[KHE88]

"radiosurgery" can be either single fraction or fractionated.

Stereotactic radiosurgery—an organized neurosurgery-sanctioned definition

"Stereotactic radiosurgery—an organized neurosurgery-sanctioned definition" published on Jan 2007 by American Association of Neurological Surgeons.

thejns.org

The surgeons are quite vehement about calling everything radiosurgery.

The truth is it's a stupid debate, but I agree with the surgeons that it makes more sense to just call everything radiosurgery rather than defining a separate term based on number of fractions when technique is the same.

 

[Neuronix]

"radiosurgery" can be either single fraction or fractionated.

"Stereotactic Radiosurgery (SRS) typically is performed in a single session, using a rigidly attached stereotactic guiding device, other immobilization technology and/or a stereotactic image-guidance system, but can be performed in a limited number of sessions, up to a maximum of five. "

Ok. I'm wrong on this one. It's not as rigidly defined as I thought.

 

[Pointless]

I always separated single fraction as SRS and fractionated as SRT. I do agree that it is an entirely stupid debate

 

[Palex80]

6. PTV margin is hotly debated. There is a question of technical accuracy depending on your linac setup and there is a question of subclinical spread. All of these tumors have microscopically positive margins, so you know there is still disease there. I tend to do 1 mm PTV on GK and 2 mm PTV on linac. There is a lot of variability in contouring, so at least we have the consensus paper as a starting point (https://www.sciencedirect.com/science/article/pii/S0360301617339536?via=ihub).

You certainly need some margin. 2mm in SRS also seems promising: Stereotactic radiosurgery of the postoperative resection cavity for brain metastases: prospective evaluation of target margin on tumor control. - PubMed - NCBI

 

[SneakyBooger]

UPDATE:

CNS tumor conference this morning (5 neurosurgeons, 6 rad oncs, 2 neurorads, etc).

Disposition: Proceed with LITT

Here is the most recent MRI. Quite a bit of edema with 7 mm midline shift.

 

[evilbooyaa]

What is LITT?

 

[SneakyBooger]

Laser Interstitial Thermal Therapy

 

[SneakyBooger]

Here is a nice review of LITT (and radionecrosis):

Frontiers | Brain Radiation Necrosis: Current Management With a Focus on Non-small Cell Lung Cancer Patients

As the prognosis of metastatic non-small cell lung cancer (NSCLC) patients is constantly improving with advances in systemic therapies (immune checkpoint blo...

www.frontiersin.org

"Invasive Interventions

LITT is a stereotactic-guided minimally invasive ablative technique that generates high temperature, resulting in tissue coagulation necrosis, angiogenesis eradication, and cellular apoptosis. The use of LITT-guided MRI allows to control accurately the delivery, and to spare the surrounding healthy tissues. LITT has been used in several situations in neurology, including RN. Most of the available data come from small retrospective studies. Rao et al. reported the results of MRIguided LITT for 12/15 (80%) NSCLC patients with suspected RN or LR after SRT for BM. On average, the lesion size measured 3.7 cm. Authors were able to perform 3.3 ablations per treatment, in a total ablation time of 7.5 min. The local control was high (76%) at a median follow-up of 6 months, with two patients experiencing recurrence at 6 and 18 weeks after the procedure (72). The largest series, from the University of Arizona, consisted of 25 patients with suspected RN, occurring after treatment for 18 primary brain tumors and 7 BM. Progression free and overall survival rates in patients with BM were 11.4 and 55.9 months, respectively. The quality of life analysis showed an improvement on mental health and vitality at 12 months (73). One of the advantages of this technique is the possibility to perform a biopsy prior to treatment to confirm the diagnosis of RN."

The biopsy results with LITT is almost always RN (at least in our pts). But, I don't think they attempt too aggressive of a biopsy as the results don't change the decision to proceed with LITT since it can also be useful to treat a recurrence, if one were to be found. In other words, the treatment is already going to be LITT whether they find RN or recurrence.

 

[Neuronix]

In my experience laser ablation controls most RT necrosis. Actual tumor grows right back out of the LITT cavity, sometimes very quickly.

 

[evilbooyaa]

Interesting. Haven't seen that before. Would be a nice tool in the arsenal besides steroids, Avastin, and surgery.

 

[scarbrtj]

Just on the nomenclature here:
SRS (stereotactic radiosurgery) = 1 fraction brain. Some people use it for single fraction spine (i.e. spine SRS) while others call single fraction spine SBRT or SABR.

FSRT (fractionated stereotactic radiation therapy) = Multi-fraction brain stereotactic. In the USA this implies up to 5 fractions. In other countries (usually Germany), they sometimes refer to IMRT w/ IGRT with PTV margins 3 mm or less as FSRT. This is in part because some international centers use Cyberknife for long course fractionated treatments (e.g. 28 fractions), while we don't usually do this in the USA.

From a billing standpoint, SRS means 1 fraction brain only. Multi-fraction is called SBRT. Anything in the spine, even single fraction, is SBRT.

I once wrote an email kind of like this to Varian. Their response: the customer is not always right.

 

[Mandelin Rain]

So I am seeing a young guy who had a solitary cerebellar met from colorectal cancer. Was subtotally resected initially and had a 3x 3 cm type cavity. I treated the cavity + 3mm to 30Gy in 5 fx. No progression for about 1.5 years, then had slow radiographic progression over serial scans with stable clinical picture. All the typical systemic stuff was tried, but it continued to progress slowly. I had the surgeon look at him and he did a repeat crani with perhaps a more aggressive surgery. He's had several post op complications requiring a graft revision and VP shunt etc... But that has all healed and now he comes back in walking and talking normally, no symptoms, and only slight CN XI and XII asymmetry on exam. Cavity is large on MRI, about 5 cm with peripheral enhancement 8 weeks out from surgery.

Overall, he is >2 years out from previous XRT. Still only site of disease.

Any suggestions? I'm thinking a larger, partial brain volume covering the cerebellar hemisphere and dura in maybe 15 fractions. 2.5Gy fractions to cover edema and dose paint the enhancement a bit. Does that sound reasonable?

 

[xrthopeful]

To me you could make your target large (including edema etc) and treat to a low dose if you wish - but to me I think you have to be aggressive given that this is the only site of disease. 30/5 may not have been enough to begin with given the apparent natural history. plus It's colorectal histology. He's at risk for necrosis anyways, so just go all in.

I don't see any reason to cover the edema.

whatever you're going to treat, make it as small as possible and go high.