re-Irradiation of brainstem lesion after previous SRS

[Kroll2013]

Dear colleagues,

I need your advice.

67 yo female, with metastatic breast cancer history to the bone, brain and lung.
Her disease was stable with second line treatment: Bone lesions symptomatic and stable, regression of lung lesions, with single ring enhanced secondary lesion of the right poster-lateral aspects of the pons at the level of the right middle cerebellar peduncle (1.4cm, PTV 1,6cc).
she received single fraction SRS 15Gy marginal dose in august 2020.
she tolerated very well with very good response till February 2021, when she presented with complete right peripheral facial palsy. Brain MRI showed progression of the same BS lesion with peri-lesional edema, as well as too new mm cerebellar lesions. Pet CT showed progression of the bony lesions, stable lung lesions.

My plan is to give her Whole Brain with HS, SIB to the BS and cerebellar lesions, since she is progressing outside the brain too with no proof of potential effective third line treatment.
But what dose to give as re_rt to the BS lesion almost 7 month after first SRS?

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[RadOncMegatron]

Very bad situation and not sure how much we can make this better. VMAT SIBing the recurrent area is fine but the question is how much better can we do than 30 Gy in 10? My opinion is 30 Gy in 10 is well tolerated after or before SRS. One of the best things to do is not hurt this patient. 40 Gy SIB the new lesions, but with systemic and intracranial progression I’d be careful. If you really wanted to be “fancy” do a 3 iso plan that avoids whole brain and give 30 Gy to the recurrent area and 40 Gy to the 2 new lesions as this patient will need 10 treatments anyway.

 

[Palex80]

Tough case.
A few quick questions:
How many new lesions are there? How big are they?
Any systemic therapy options? Her2 positive/negative?

I no longer use SRS for brainstem lesions. I feel that fractionated stereotactic RT is better in most of these patients.

 

[Kroll2013]

Tough case.
A few quick questions:
How many new lesions are there? How big are they?
Any systemic therapy options? Her2 positive/negative?

I no longer use SRS for brainstem lesions. I feel that fractionated stereotactic RT is better in most of these patients.

I totally agree with SFRT for brainstem lesions

there are 3 lesions
relapsing one volume with PTV 2mm : 6.7cc
2 others < 2cc each

Her2 negative

 

[Palex80]

I totally agree with SFRT for brainstem lesions

there are 3 lesions
relapsing one volume with PTV 2mm : 6.7cc
2 others < 2cc each

Her2 negative

Thank you.

My feeling is that with almost 6 months progression free survival after 15 Gy on that brainstem lesion, a further local progression within the next half year is highly probable after a repeat irradiation.
You can no longer give a high, ablative dose like the one that was given with the SRS. So, if 1 x 15 Gy failed to control that lesion, any "safe dose" you are going to give now will probably not be enough.

That braintem lesion will likely kill the patient, thus one option would also be NOT to give WBRT now, ignore the two other tiny mets (provided they are not in critical areas, do not have lots of edema) and simply treat the brainstem lesion with a "safe" palliative dose, like 10-12 x 3 Gy and observe. This approach will lead to less side-effects than WBRT and may lead to the same OS down the road. If the tiny lesions do progress in 3 months, while the brainstem lesion seems controlled, you can always still SRS them then.

 

[communitydoc13]

Given time course and appearance of lesion, could this be radionecrosis?

The fact that there are other areas of intracranial progression and systemic progression makes recurrence more likely, but this picture 7 mos after stereotactic treatment could easily be necrosis. Is there any diffusion imaging or Spect available to help you out? Facilitated diffusion would lead you to think necrosis.

I agree something with minimal toxicity appropriate. I like Palex's plan for fractionated treatment to brainstem alone. Would be aggressive with steroids throughout course of treatment

 

[TheWallnerus]

Thank you.

My feeling is that with almost 6 months progression free survival after 15 Gy on that brainstem lesion, a further local progression within the next half year is highly probable after a repeat irradiation.
You can no longer give a high, ablative dose like the one that was given with the SRS. So, if 1 x 15 Gy failed to control that lesion, any "safe dose" you are going to give now will probably not be enough.

Aside:
Do we overuse "ablative" in rad onc. 15/1, 18/1, 24/1, 27/3, 30/5, 50/5, 56/4, 68/15, 75/25... all "ablative"? Moe from the Three Stooges would say "I keep callin' it ablative but it keeps comin' back!"

Very bad situation and not sure how much we can make this better. VMAT SIBing the recurrent area is fine but the question is how much better can we do than 30 Gy in 10? My opinion is 30 Gy in 10 is well tolerated after or before SRS. One of the best things to do is not hurt this patient. 40 Gy SIB the new lesions, but with systemic and intracranial progression I’d be careful. If you really wanted to be “fancy” do a 3 iso plan that avoids whole brain and give 30 Gy to the recurrent area and 40 Gy to the 2 new lesions as this patient will need 10 treatments anyway.

I no longer use SRS for brainstem lesions. I feel that fractionated stereotactic RT is better in most of these patients.

How outside the box would 30 Gy/20 fx BID whole brain be with 40/20 SIB to the lesions. Call it VFAR... very fractionated ablative radiotherapy; it's designed to minimize late effects worry from the previous 15/1 to the brainstem.

 

[Bequerel]

you gave her a few months of improved quality of life by slowing progression in her brainstem. If this in fact progression in the brainstem 6 months s/p 15Gy x 1, then her prognosis is poor and I’d favor hospice over the fatigue and inconveniences that comes with 2 weeks of once daily or twice daily radiotherapy treatments. Her overall survival time is in weeks not months with or without further treatment.

 

[evilbooyaa]

7Gy x 3, counsel on risk of death from this treatment. If she survives 3 months, SRS the other 2 (probably growing) lesions.

Would've preferred to see 6Gy x 5 upfront, personally.

 

[Ray D. Ayshun]

Additionally, are the "new" lesions smaller than the slice thickness of the scan? Iow, is there a chance they're not new, and that this is radio necrosis in the other one? Systemic disease did and didn't progress. In any case, what about decadron and reMr in 4-6 weeks? Either way, there but by the grace of god go I.

 

[Neuronix]

Brain pet or some radioactive test to confirm active disease, then radiate preferably with bevacizumab and pray. Dose? 6 Gy x 5 fx no ptv with a good stereo setup. Not wrong to make up another dose. I almost never do wbrt anymore but could do a focal 30-40 in 10 if you want and stereo the other lesions.

I don't trust advanced MRI/MRS in the skull base/infratentorial fossa, too much artifact.

 

[Lamount]

Brain pet or some radioactive test to confirm active disease, then radiate preferably with bevacizumab and pray. Dose? 6 Gy x 5 fx no ptv with a good stereo setup. Not wrong to make up another dose. I almost never do wbrt anymore but could do a focal 30-40 in 10 if you want and stereo the other lesions.

I don't trust advanced MRI/MRS in the skull base/infratentorial fossa, too much artifact.

I’m not a CNS guy (so this may be a stupid question)...
...but why not 3Gy x 10 with 1-2 mm margin and stereo setup?

 

[Neuronix]

Sure why not. I just think 30/10 is unlikely to provide much control if 15/1 didn't but again I'm just making it up in this case. I don't think there is data for brainstem repeat RT (though I bet someone can find a retrospective series--there's always a retrospective series).

 

[emt409]

It’s been a while since I posted here. Yes, I’m “that UAB resident” now going on CNS faculty elsewhere.

But for what it’s worth, I do have experience in this situation.

Doesn’t sound like WBRT buys you anything here with a single lesion progressing after SRS and two new PF lesions, so not sure why you are doing that.

In this situation, I’d give 25Gy/5fx fSRS to the pons lesion and 30Gy/5fx to two new PF lesions with half dose avastin (7.5mg/kg) on top of minimum 4mg BID dex.
A more conservative approach would be 20Gy/5fx to whole PF including pons lesion (would also rec Avastin). No need to carpet bomb the whole cerebrum for this lady with no supratentorial lesions.

We do have some clinical data showing Her2+ lesions more in general radio resistant. You didn’t give us receptors here, so not sure if that applies, but may be useful to someone.

 

[TheWallnerus]

In this situation, I’d give 25Gy/5fx fSRS to the pons lesion and 30Gy/5fx to two new PF lesions with half dose avastin (7.5mg/kg) on top of minimum 4mg BID dex.
A more conservative approach would be 20Gy/5fx to whole PF including pons lesion (would also rec Avastin).

Giving 15/1 to the pons, followed by 25/5, or 20/5, to the pons ~8 mos later, and expecting it to be safe, says many things without coming straight out and saying them. With allowing no forgiveness due to the elapsed time...

"Giving 15/1 to the pons, followed by 25/5, or 20/5, to the pons ~8 mos later, and expecting it to be safe, says many things." What things exactly? Few MDs would tolerate 108 Gy/54 fx over an 8 month time period to the pons e.g. For that matter, few might tolerate 64 Gy/32 fx in one sitting. Yet since these are equivalent to 15/1+25/5, or to 15/1, respectively, if α/β=2, this says the α/β of the pons is probably greater than 2. And being able to give the pons 40 Gy in 6 fractions over 8 months means it's repairing RT damage rather handily (if the patient remains un-paralyzed or has no CN toxicity).

Agree that 15/1 plus 25/5 is probably safe. Although as shown, 15/1+30/20 has appeal for keeping side effects low plus hitting the tumor harder than 20/5 might. But it makes someone come in twice-a-day for two weeks, which seems weird and/or too heavy handed. (Although again there is randomized data for twice-a-day palliative brain RT.) If I were my own radiation oncologist and treating myself, I reckon I'd give my pons 15/1 and 30/20 if I failed locally. Giving *myself* 5 Gy, or 4 Gy, retreat pons fractions might scare me a little. A little.

But being able to give 15/1 followed by 25/5 months later means the pons α/β estimates are not too reliable and/or the CNS has a lot of capacity for forgiveness. Unknown Zones worthy of CNS rad onc research?!

 

[Palex80]

One argument certainly is:

However, this situation is more like a Catch-22-situation:

 

[Neuronix]

But being able to give 15/1 followed by 25/5 months later means the pons α/β estimates are not too reliable and/or the CNS has a lot of capacity for forgiveness. Unknown Zones worthy of CNS rad onc research?!

Nobody said this was safe. I'm saying if you don't control the tumor, the patient dies. Palex has the right idea here. 5x5 is a wimpy dose imo but will probably work for a few months before the tumor grows again. Then again maybe 6x5 is too much and I would kill the patient. My money is on the tumor killing the patient, not RT necrosis.

 

[DebtRising]

Either do something gentle or don’t do any active treatment. You can’t safely give a dose above the first dose, which was a fine dose. Therefore you cannot control this.

agree of course with taking all steps available to rule out radiation necrosis if you are going to re treat

 

[Kroll2013]

THANK YOU GUYS.
I am really lucky to have you for back up.
xoxoxo

 

[evilbooyaa]

It’s been a while since I posted here. Yes, I’m “that UAB resident” now going on CNS faculty elsewhere.

But for what it’s worth, I do have experience in this situation.

Doesn’t sound like WBRT buys you anything here with a single lesion progressing after SRS and two new PF lesions, so not sure why you are doing that.

In this situation, I’d give 25Gy/5fx fSRS to the pons lesion and 30Gy/5fx to two new PF lesions with half dose avastin (7.5mg/kg) on top of minimum 4mg BID dex.
A more conservative approach would be 20Gy/5fx to whole PF including pons lesion (would also rec Avastin). No need to carpet bomb the whole cerebrum for this lady with no supratentorial lesions.

We do have some clinical data showing Her2+ lesions more in general radio resistant. You didn’t give us receptors here, so not sure if that applies, but may be useful to someone.

Welcome back! You have certainly been quite well versed on CNS literature than most, went to a program known for pushing the edge of linac-based SRS, and I personally look forward to you becoming an academic CNS attending.

 

[FrostyHammer]

Welcome back! You have certainly been quite well versed on CNS literature than most, went to a program known for pushing the edge of linac-based SRS, and I personally look forward to you becoming an academic CNS attending.

Ah the classic SDN behavior:

Person posts things on Twitter deemed unsatisfying to SDN community -> SDN gets pissed at the person and lets fly many posts against him

Same person actually comes on SDN -> SDN praises the person with ebullient sycophantry.

Gotta love it.

 

[medgator]

Ah the classic SDN behavior:

Person posts things on Twitter deemed unsatisfying to SDN community -> SDN gets pissed at the person and lets fly many posts against him

Same person actually comes on SDN -> SDN praises the person with ebullient sycophantry.

Gotta love it.

Calling a spade, a spade... Terrible behavior.

 

[Ray D. Ayshun]

Eh, it took courage to wade into enemy territory to offer more ways to fry this brainstem.

 

[evilbooyaa]

Ah the classic SDN behavior:

Person posts things on Twitter deemed unsatisfying to SDN community -> SDN gets pissed at the person and lets fly many posts against him

Same person actually comes on SDN -> SDN praises the person with ebullient sycophantry.

Gotta love it.

Can both criticize a man for being an asshat while recognizing his knowledge base and passion for intracranial radiation oncology, my dude/dudette.

I criticize the actions of a man/woman, not everything about that man/woman. Usually.

 

[Radonc90]

My 2 cents...

- The BS lesion received 1500 cGy/1fx back in Aug 2020, what you see could be necrosis with edema.
I'd order a PET scan of the brain to r/o radionecrosis. If confirmed to be radionecrosis, then Rx is decadron
for a few weeks, then taper it.

- If this is truly tumor (and not radionecrosis), further RT is unlikely to control it. This is in contrast to someone
treated with the same Tx but 5 yrs ago and now back with recurrent disease, you can Tx again. So far, the
interval is only 7 months since Aug. 2020, I have a hunch this is necrosis.

- I'd avoid WBRT, if possible.

Anyway, I am trying to be humane to the pt, she suffered enough, no need to add more agony to her life...

Please follow up with what you do so we can all learn...

 

[radoncopotamus]

Start her on Avastin and get urgent advanced imaging.