Medulloblastoma target minimum dose coverage

[Kroll2013]

---

Members don't see this ad.

Dear colleagues, what is the mininmum dose level to cover with the craniospinal field i a 34 yo female, very obese wh presents a standard risk medulloblastoma? Using a 3D conformal technique with IGRT
I know that the prescribed dose is 23.4 Gy in 13 Fr
But considering her anatomy , mean the very thick fat plane covering the target , it is quasi impossible to cover the target with the 95% IDL with exceeding 110% ( entrance dose)
Is 18 -20 Gy enough to have the same local control? By qnalgy to the studies done in young children comparing 18 vs 23.4 Gy

Thx a lot

 

[Palex80]

Use IMRT?

 

[Kroll2013]

Use IMRT?

She is a foreigner. No third party coverage. Unable to pay IMRT on her expense.

 

[Palex80]

Oh, I see...
Will the patient receive vincristine concurrently to RT?

 

[Kroll2013]

Oh, I see...
Will the patient receive vincristine concurrently to RT?

Yes. as the standard protocol

 

[Palex80]

In that case I think it's safe to "stick" to a dose of around 20 Gy. Bear in mind that lot's of data are from 2D-series, where noone really knows, what the applied dose truly was.
Do you know what the histological subtype was?
There is a chance, that this patient may have a WNT-subtype and thus an excellent prognosis (female, adult).

 

[Gfunk6]

I had a similar case last year with a man in his early 30s with standard risk medulloblastoma. With kids we would run vincristine with 23.4 Gy CSI. However talking to one of the local, academic Peds experts, she recommended as Palex did above. I actually sent his tumor block for Foundation One testing which was negative for all known high risk mutations. I therefore proceeded with lower dose CSI without vincristine. Of course he still received sequential chemo afterwards.