Repeat SABR in parallel organs

[Gfunk6]

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WHAT!?! A thread that doesn't involve the job market, ABR certification exams, or compensation??

I was wondering what your tolerance was for repeat SABR in patients that have had prior SABR in parallel organs (e.g. lung, liver, kidney).

I have a patient who had an inoperable cholangiocarcinoma by virtue of it straddling both hepatic lobes and after evaluation by a surgical oncologist. Med Onc also opined that chemo is pretty ineffective in this scenario. So I went to town with SABR (10 Gy x 5 fractions). PET/CT three months later showed metabolic CR. PET/CT six months later showed as solitary met in the right lung which was also ablated (10 Gy x 5 fractions).

Now, nine months later he apparently has an FDG-avid (small) recurrence in the dead center of the initial field. The liver around the target is most certainly dead and non-functional, but I'm a bit leery of re-treatment due to not wanting to damage/sclerose his common bile duct. Of note he does have a patent stent with normal labs (bili, etc.). If it matters, his liver function is great.

 

[Neuronix]

I think you're operating in a "data free zone" though maybe someone has a retrospective on this I'm not aware of.

I know some people try to avoid 20 Gy in 3 fractions to the CBD. One of the bigger names in the field swears by this, but I've only ever seen isolated case reports of this complication. In over 200 pancreas SBRTs I've also seen a 1% incidence of portal vein stenosis. So this stuff is real, but it's really uncommon and hard to predict.

That written, 20 Gy x 3 fractions with alpha/beta = 2 is BED 660Gy2. 50 Gy in 5 fractions with alpha/beta = 2 is BED 300Gy2. So... Can you get away with doing 50 Gy in 5 fractions again? Honestly, I would just consent the patient for these rare complications and do it. Uncontrolled disease is a much bigger risk and the more this grows, the more risk and decreased control you will have.

I would do a composite of the two SBRT plans and try to get the same objectives as I would have gotten in a single treatment (especially mean liver--for this I typically use RTOG 1112 but this is overly conservative for a met in a good liver). That's probably overly conservative too, but probably still achievable nevertheless.

 

[nkmiami]

In these kind of situations, I like to get a repeat pet 2 months later just to make sure it is real. I am not sure I would re-irradiate the common bile duct, if it is in the field. If I were to retreat, I would use Chris Crane 67.5/15 or 75/3 w/xeloda not stereo, just because it didnt work the first time. I would also consider selective y90.

 

[OTN]

I'd be worried about CBD toxicity, given the Stanford experience with overdosing in that area. I'd contour it as an avoidance structure and try very hard to limit dose. As long as dosimetry looks ok there, though, I'd be ok with retreating. I've retreated the lung before with good results, and there's data to back that up.

 

[seper]

I do it, but first ensure that metastatic disease indeed follows indolent course. Practically, that involves doing a short term-follow up with CT instead of pulling the SBRT trigger right away.
In liver specifically, lethal side effects of SBRT seem to affect adjacent organs (diaphragm necrosis, stomach perf) rather than the liver itself.

 

[evilbooyaa]

Evaluate proximity to CBD. Since it's intrahepatic bilobe cholangio I imagine it's essentially straddling the CBD. Even if the patient has a well functioning stent now, stents eventually give problems - they're not meant to be permanent solutions to a problem.

I think you've done this patient a service by giving him OS of 9 months without surgery. Is this recurrence resectable? I wouldn't be a big fan of re-SBRTing the same lesion unless I absolutely had to, but if patient was agreeable to toxicity risks of CBD stenosis (recurrent cholangiitis, procedural intervention, etc.) then OK.

 

[nkmiami]

Also got a stereo question: I have patient with oligometastatic melanoma with 5 cm acetabular lesion. What kind of dosing are you guys using in this situation. I was thinking 9-10 Gy x 4.

 

[scarbrtj]

Now, nine months later he apparently has an FDG-avid (small) recurrence in the dead center of the initial field.

A recurrence of PET avidity (sans tumor) or recurrence of tumor 9 months out? It's about 50/50 either way. Assume 80% LC prob after 50/5, PET sensitivity/specificity of 90%/75%:
..............DISEASE
..............positive....negative
Test positive....18..........20.....PPV: 18/38=47%
Test negative....2...........60
.............---------------------
.................20..........80

 

[scarbrtj]

Also got a stereo question: I have patient with oligometastatic melanoma with 5 cm acetabular lesion. What kind of dosing are you guys using in this situation. I was thinking 9-10 Gy x 4.

eh good qu. There is a ~6-9mm hole right in the top of the acetabulum where the artery pierces to keep the acetabulum alive. A necrosed acetabulum (yikes sorry femoral head!) can be pretty painful. I'd hope SBRT wouldn't hurt that artery.

 

[Neuronix]

Also got a stereo question: I have patient with oligometastatic melanoma with 5 cm acetabular lesion. What kind of dosing are you guys using in this situation. I was thinking 9-10 Gy x 4.

Depends on histology. If radioresistant I've been doing 20-24 Gy in 1 fraction. If radiosensitive 16-18 Gy. I do a very careful setup with zero margin on the gross disease (dose falloff as CTV/PTV). I've been extrapolating the doses from spine SRS and the Zelefsky et al paper for RCC showing 24 Gy in 1 fraction is best dose for RCC bone mets.

Maybe I'm crazy but I haven't had any complications yet. I do look carefully at where the dose falloff is though--i.e. not high dose through femoral head, rectum, bowel, bladder, etc...

 

[evilbooyaa]

Also got a stereo question: I have patient with oligometastatic melanoma with 5 cm acetabular lesion. What kind of dosing are you guys using in this situation. I was thinking 9-10 Gy x 4.

Eh. I'd worry about weight bearing status of that bone. I'd have to look at published dosing but wouldn't favor more than 8-9Gy x 3. Standard bone SBRT dose is 10Gy x 3, right? I definitely wouldn't do that or anything more in such a large lesion of a weight bearing bone.

 

[RickyScott]

stereo for kids with osteosarcoma and ewings 40/5,
Stereotactic Body Radiotherapy for Metastatic and Recurrent Ewing Sarcoma and Osteosarcoma

 

[scarbrtj]

stereo for kids with osteosarcoma and ewings 40/5,
Stereotactic Body Radiotherapy for Metastatic and Recurrent Ewing Sarcoma and Osteosarcoma

"The third significant late toxicity was in a patient treated with 60 Gy in 10 fractions to an osteosarcoma metastasis of the femoral head. The entirety of the femoral head and neck was involved by disease and received the prescription dose. Four and 8 months after SBRT, he developed grade 2 pathologic fracture and avascular necrosis of the femoral head, respectively. Both were managed conservatively and have not required surgical intervention."

Still... OUCH. You mess with that artery you get AVN like 100% of the time. I'm not an orthopod but I play one on TV.

 

[Neuronix]

Intact disease causes pathologic fractures. Disease response to RT causes pathologic fractures. You're damned if you do and damned if you don't.

 

[scarbrtj]

Intact disease causes pathologic fractures. Disease response to RT causes pathologic fractures. You're damned if you do and damned if you don't.

True, but one is like an active damnation and the other more of a passive damnation. It is a truism that for patients I have not treated I am far less likely to be held responsible for their bad outcomes.

 

[nkmiami]

Intact disease causes pathologic fractures. Disease response to RT causes pathologic fractures. You're damned if you do and damned if you don't.

big lytic lesion right now and he is in a lot of pain and cant walk.

 

[evilbooyaa]

Intact disease causes pathologic fractures. Disease response to RT causes pathologic fractures. You're damned if you do and damned if you don't.

Agreed, but perhaps one could treat the disease while minimizing risk of treatment related necrosis.

 

[medgator]

Sometimes, there is nothing wrong with 10-15 fractions

 

[nkmiami]

Sometimes, there is nothing wrong with 10-15 fractions

I know- was hoping to get some kind of magical/theoretical syngery between doses 8-10 Gy with radiation and immunotherapy that he is on.

 

[scarbrtj]

I know- was hoping to get some kind of magical/theoretical syngery between doses 8-10 Gy with radiation and immunotherapy that he is on.

30 Gy in 5 fractions ¯\_(ツ)_/¯
Still SBRT 😉

 

[Radiator20]

big lytic lesion right now and he is in a lot of pain and cant walk.

May still be in pain after RT due to persistent disruption of the acetabular articular surface where the tumor once was. If that happens, could consider looking for a good IR who does acetabuloplasty—I’ve seen it do a lot of good in this situation. Not sure how widespread that procedure is yet (and does seem like it requires significant expertise) but something about the cement restoring the normal contour of the acetabular surface seems like it can significantly help the pain.

 

[seper]

Does percutaneous acetabuloplasty have any track record in metastatic patients? I'd suspect results, however one defines them, will be just as lousy as with vertebroplasty.

May still be in pain after RT due to persistent disruption of the acetabular articular surface where the tumor once was. If that happens, could consider looking for a good IR who does acetabuloplasty—I’ve seen it do a lot of good in this situation. Not sure how widespread that procedure is yet (and does seem like it requires significant expertise) but something about the cement restoring the normal contour of the acetabular surface seems like it can significantly help the pain.

 

[medgator]

Does percutaneous acetabuloplasty have any track record in metastatic patients? I'd suspect results, however one defines them, will be just as lousy as with vertebroplasty.

subjectively, I've seen some pretty good pain relief in pts with bad spinal mets with associated loss of vertebral body height who got combo kypho and xrt, more so than I would have expected with xrt alone

 

[Palex80]

Without seeing an image it's hard to judge, but I would consider other options rather than repeat-SBRT (if possible) such as RFA or microwave ablation.
However, it is quite possible that the lesion is in a tough spot to apply any of these modalities.

 

[emt409]

WHAT!?! A thread that doesn't involve the job market, ABR certification exams, or compensation??

I was wondering what your tolerance was for repeat SABR in patients that have had prior SABR in parallel organs (e.g. lung, liver, kidney).

I have a patient who had an inoperable cholangiocarcinoma by virtue of it straddling both hepatic lobes and after evaluation by a surgical oncologist. Med Onc also opined that chemo is pretty ineffective in this scenario. So I went to town with SABR (10 Gy x 5 fractions). PET/CT three months later showed metabolic CR. PET/CT six months later showed as solitary met in the right lung which was also ablated (10 Gy x 5 fractions).

Now, nine months later he apparently has an FDG-avid (small) recurrence in the dead center of the initial field. The liver around the target is most certainly dead and non-functional, but I'm a bit leery of re-treatment due to not wanting to damage/sclerose his common bile duct. Of note he does have a patent stent with normal labs (bili, etc.). If it matters, his liver function is great.

Good case. I agree with one of the answers above to get a repeat PET to make sure it's real. If it is, beam on, and then follow him with HIDA scans in addition to normal imaging, and if you see the duct start to stricture, send him for a stent.

One of my mentors has always said, if you're going to treat like a surgeon, you need to learn to manage complications like a surgeon. CBD stricture is a common problem in the gen surg world and frequently managed.

 

[Radiator20]

subjectively, I've seen some pretty good pain relief in pts with bad spinal mets with associated loss of vertebral body height who got combo kypho and xrt, more so than I would have expected with xrt alone

Agree with medgator — in my experience there can be significant, rapid relief from vertebroplasty when there’s a component of mechanical instability. It’s a broken bone, after all. RT can fix the tumor pain but unless the bone heals or is stabilized, still going to hurt.

 

[medgator]

Agree with medgator — in my experience there can be significant, rapid relief from vertebroplasty when there’s a component of mechanical instability. It’s a broken bone, after all. RT can fix the tumor pain but unless the bone heals or is stabilized, still going to hurt.

The issue is when some think kypho is enough by itself, which it certainly isn't, for multiple reasons, including getting durable pain control

 

[Radiator20]

The issue is when some think kypho is enough by itself, which it certainly isn't, for multiple reasons, including getting durable pain control

Totally agree. Need RT to stop pain from local tumor growth and provide local control. If there’s also mechanical instability, vertebroplasty in addition can stabilize and thereby relieve pain due to the instability—but it’s never a substitute for RT as it accomplishes neither of the things RT does.

 

[Lamount]

WHAT!?! A thread that doesn't involve the job market, ABR certification exams, or compensation??

I was wondering what your tolerance was for repeat SABR in patients that have had prior SABR in parallel organs (e.g. lung, liver, kidney).

I have a patient who had an inoperable cholangiocarcinoma by virtue of it straddling both hepatic lobes and after evaluation by a surgical oncologist. Med Onc also opined that chemo is pretty ineffective in this scenario. So I went to town with SABR (10 Gy x 5 fractions). PET/CT three months later showed metabolic CR. PET/CT six months later showed as solitary met in the right lung which was also ablated (10 Gy x 5 fractions).

Now, nine months later he apparently has an FDG-avid (small) recurrence in the dead center of the initial field. The liver around the target is most certainly dead and non-functional, but I'm a bit leery of re-treatment due to not wanting to damage/sclerose his common bile duct. Of note he does have a patent stent with normal labs (bili, etc.). If it matters, his liver function is great.

As others have mentioned, there is a dearth of data for this situation. Is RFA an option? If the first course of RT failed to control the disease, perhaps another modality would have more luck.