variant squam with in-transit mets going up the arm

[Ray D. Ayshun]

kinda miserable situation for a guy with a bunch of in transit cutaneous mets more or less encompassing the forearm, which are bleeding, etc. Has to wear a whole arm bandage and is beginning to lose function. It's a variant squam and he's a txp patient with no io options who can't tolerate chemo. Got post-op rt to a portion of this area 3 years ago. Wondering what the craziest fields folks have done for situations like these. Whole forearm ap/pa? Arcs/imrt to just the superficial areas/skin in order to try to cut dose down centrally? Nothing? All the side effects we'd consent people for if we (re)treated the whole forearm are gonna happen sooner than later if I do nothing.

can private msg pics if that would inform advice. pretty extreme and don't want to just post on the web.

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[elementaryschooleconomics]

kinda miserable situation for a guy with a bunch of in transit cutaneous mets more or less encompassing the forearm, which are bleeding, etc. Has to wear a whole arm bandage and is beginning to lose function. It's a variant squam and he's a txp patient with no io options who can't tolerate chemo. Got post-op rt to a portion of this area 3 years ago. Wondering what the craziest fields folks have done for situations like these. Whole forearm ap/pa? Arcs/imrt to just the superficial areas/skin in order to try to cut dose down centrally? Nothing? All the side effects we'd consent people for if we (re)treated the whole forearm are gonna happen sooner than later if I do nothing.

can private msg pics if that would inform advice. pretty extreme and don't want to just post on the web.

I would treat, I don't think this is an unreasonable field size/situation.

Taking a step back, the question is "what's the worst that could happen". Do you have the old records/Dosimetry from the prior treatment? Was it big or little? Was it a definitive dose?

Is this the only site of disease?

For skin with a re-irradiation component, I'll admit that I go full boomer and prefer BID. Obviously, the data in this space is garbage, and ironically I think some of the stuff from the 90s is still relevant today. Something like 5040cGy in 21 days (42 fractions, 1.2Gy per fraction). In an ideal world, yeah, something more conformal than APPA would be theoretically better from a toxicity standpoint.

Would it be possible to do it with electrons? Probably a question better directed to your physics team.

 

[Ray D. Ayshun]

I would treat, I don't think this is an unreasonable field size/situation.

Taking a step back, the question is "what's the worst that could happen". Do you have the old records/Dosimetry from the prior treatment? Was it big or little? Was it a definitive dose?

Is this the only site of disease?

For skin with a re-irradiation component, I'll admit that I go full boomer and prefer BID. Obviously, the data in this space is garbage, and ironically I think some of the stuff from the 90s is still relevant today. Something like 5040cGy in 21 days (42 fractions, 1.2Gy per fraction). In an ideal world, yeah, something more conformal than APPA would be theoretically better from a toxicity standpoint.

Would it be possible to do it with electrons? Probably a question better directed to your physics team.

No e-. Lesions are basically circumferential, and given the appearance and anatomic considerations, it feels like an elective volume is necessary as he will likely recur marginally in the short term. I'm not terribly worried about the reRT aspect per se. I'm more wondering if this is even worth trying. I havent seen any case reports of total forearm rt etc.

 

[medgator]

These immunosuppressed/transplant/autoimmune patients with nasty skin cancers can be some of the toughest cases to deal with... No IO options, no immune system to help keep a durable response after initial tx

 

[madchemist89]

This sounds like a palliative situation. I would treat with more aggressive palliative dosing and ensure a strip of tissue is spared.

 

[medgator]

No e-. Lesions are basically circumferential, and given the appearance and anatomic considerations, it feels like an elective volume is necessary as he will likely recur marginally in the short term. I'm not terribly worried about the reRT aspect per se. I'm more wondering if this is even worth trying. I havent seen any case reports of total forearm rt etc.

Wrap in bolus with photons?

 

[Ray D. Ayshun]

Wrap in bolus with photons?

That's the current plan. No plan to spare a strip as there isn't one/id expect short term progression there. Planning on 37.5/15 with arcs to try to spare the interior as much as possible. Just wondering if this makes any sense.

 

[TheWallnerus]

kinda miserable situation for a guy with a bunch of in transit cutaneous mets more or less encompassing the forearm, which are bleeding, etc. Has to wear a whole arm bandage and is beginning to lose function. It's a variant squam and he's a txp patient with no io options who can't tolerate chemo. Got post-op rt to a portion of this area 3 years ago. Wondering what the craziest fields folks have done for situations like these. Whole forearm ap/pa? Arcs/imrt to just the superficial areas/skin in order to try to cut dose down centrally? Nothing? All the side effects we'd consent people for if we (re)treated the whole forearm are gonna happen sooner than later if I do nothing.

can private msg pics if that would inform advice. pretty extreme and don't want to just post on the web.

Wonder if an approach like this might be feasible for wide patches of skin needing homogenously applied superficial RT

World-first non-invasive skin cancer treatment trialled on Sydney woman

www.9news.com.au

We need more thoughtful effort (and industry-initiated tools/software) for electron (even "dynamic") arc therapy techniques

Clinical implementation of a wide-field electron arc technique with a scatterer for widespread Kaposi’s sarcoma in the distal extremities - Scientific Reports

A novel wide-field electron arc technique with a scatterer is implemented for widespread Kaposi’s sarcoma (KS) in the distal extremities. Monte Carlo beam modeling for electron arc beams was established to achieve <2% deviation from the measurements, and used for dose calculation. MC-based...

www.nature.com

 

[RadOncBeamer]

I think that approach sounds reasonable. Good arm immobilization with aquaplast for the hand is something I've done before. Arcs with bolus to spare the interior if you can get insurance approval, no need to blast through bone. With circumferential lesions, I'm not sure there's a good way to spare strip of skin. However, lymphedema/forearm edema is inevitable with tumor progression, so I think a circumferential volume is justified in this situation. If you're looking for more concrete numbers in the re-RT setting, Chris Barker posted this article on themednet suggesting a cumulative BED of 110, though obviously this is a pretty data-free zone.

Reirradiation of recurrent skin cancer of the face. A successful salvage modality - PubMed

Reirradiation is a feasible treatment alternative for recurrent skin cancer of the face when cosmesis is a concern.

pubmed.ncbi.nlm.nih.gov

 

[metview]

How exactly would you immobilize the forearm here? Wrap in bolus and place in vak-lok?

 

[Ray D. Ayshun]

How exactly would you immobilize the forearm here? Wrap in bolus and place in vak-lok?

That's what I did. Ill post pics in 6 months after this goes according to plan...

 

[Reaganite]

Not sure about depth of lesions but have done some hdr "flap wraps"

 

[grenz]

Not sure about depth of lesions but have done some hdr "flap wraps"

I have seen HDR surface brachy work really well here. There are multiple products to facilitate it or you could embed catheters in a custom aquaplast mold

 

[evilbooyaa]

If truly circumferential, beam on and send for pre-emptive lymphedema therapy during treatment (as tolerated).

It's a long scalp in terms of treatment technique. Equivalence of treat the bowl but not the soup with VMAT. Would not do AP/PA and treat through all the muscle/bone for no reason.

Could do HDR if all lesions are superficial enough but not sure that really buys you an advantage to VMAT.

Probably stick with 2Gy/Fx for the entire area given the size. I'm not sure of any proven utility to BID here.