Interesting Case

[thomascarpenter]

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Hi first time poster here.
Re-irradiation of spinal cord beyond cord tolerance is not something I have seen often and I would really appreciate your feedback on how you would approach this case.

50yo WF with L4 chordoma s/p GTR and adjuvant PA/lats XRT to 54Gy/30 fxs back in 2000. It recurred 7 years later in the L4 paraspinous region and the patient underwent re-excision, corpectomy and posterior fusion with case placement. The mass recurred again in the L4 paraspinal region again few weeks back in 6/2010 with stable neurological deficits since the re-excision in 2007. There is alot of hardware and the mass appears to be encroaching near the neural foramina. The neurosurgeons don't want to touch him anymore. The mass will likely continue to get larger and become more symptomatic in the near future.

Given the long interval since the initial XRT, my attending is leaning towards retreatment with radiosurgery, but i don't feel as optimistic. We have gone back and forth on this case.

Any thoughts?

 

[Gfunk6]

In most cases, L4 should be way below the conus so spinal cord myelopathy should be a non-issue.

 

[Palex80]

Gfunk6 is principally right.

However retreatment with a high dose could result into damage on spinal nerves and plexus lumbosacralis. I have seen 2 patients with rectal cancer after neoadjuvant RT being retreated for local recurrence with high doses and experiencing nerval damage (up to paraplegia).
The tolerance dose of the nerves is higher than the one of the spinal cord, but it's still an issue you have to bear in mind when retreating, especially when you are dealing with chordoma patients, who tend to live long, due to the indolent nature of their disease.

Personally I would not opt for radiosurgery. The precision is great, but do you really want to give a high single dose to a pretreated area, where you are concerned about complications?
I would opt for a high-conformal technique (IMRT) and try to minimize safety margins with reproducible fixation and IGRT. I would definetely fractionate.
Perhaps hyperfractionation could be a good idea in this special case (1.1 Gy BID?).

I have no idea what kind of dose you want to give to this patient, I would probably try out something like 1.1 BID up to 44 Gy (+ more Gy if you are brave...).
It's still a palliative treatment though.

Do you have access to carbon ion treatment?
Heidelberg-Uni has published some very good results with carbon ions.

 

[deleted4401]

I'll let my former institutional bias show ... I'd say either SRS or fSRT. I'd just be hard pressed to re-irradiate that region (regardless that conus is above it) with IMRT, just because we never really did it that way.

Tough case.

S

 

[radiaterMike]

There is emerging data for SRS/SBRT in previously irradiation patients. The recent QUANTEC review also discusses studies of reirradiation as well. I think I would opt for SRS/SBRT. In discussing the risks the patients, you would also discuss the risks of not treating (i.e. tumor progression).

I'll let my former institutional bias show ... I'd say either SRS or fSRT. I'd just be hard pressed to re-irradiate that region (regardless that conus is above it) with IMRT, just because we never really did it that way.

Tough case.

S

 

[OTN]

I think it's going to be tough to get enough dose in to do any good in a chordoma unless you use radiosurgery or hypofractionate. I took the last sacral chordoma patient I had to 72 Gy...and that was after resection.

I agree that lumbosacral plexopathy is a very real concern in her case, but I don't see what other options you have if surgical resection is out of the question. L4 should place you below the level of the cord.

I would go with SRS/SBRT. Dose = 😕 Now, if she lives close to a proton center, chordoma is one of the tumors for which data (!) actually exists that suggests a benefit to charged particle therapy.

t

 

[medgator]

The patient is definitely between a rock and a hard place. To get a biologically useful dose in, you're definitely looking at the potential for toxicity. As Palex80 alluded to, the tolerance of the nerves/LS plexus is higher than the cord, but not high enough to really get a curative dose in for a chordoma IMO. It's either your treatment or the tumor that is going to impact that plexus.

Is there a proton facility nearby?

 

[Palex80]

So, will u treat and will u treat?