Radiosurgery for Gliomas
Radiosurgery is a technique that focuses a very small beam of radiation on a precise spot and uses a large single dose to destroy a tumor. The technique is ideally suited for small benign tumors, or well circumscribed malignant tumors (like a single brain metastases.) The benefits in using this technique for gliomas (which have more diffuse or invading margins) is less clear. There may be some benefit to fractionated radiosurgery (go here) and see the RTOG 0023 here.
Cyberknife section here
Issues to consider:
RTOG 93-05 trial
see references and studies here and here
see discussion of radiation target.
other sites: Johns Hopkins, Glioma site
radiosurgery for low grade glioma here and here
|Is there a survival benefit?
from the references noted, there is some evidence that survival may be prolonged (but the ASTRO position on benefit is negative see here.)
- Shrieve (Harvard) noted survival in GBM of 19.9 mos and longer by class (III 29.5 mos, IV 19,2 mos and V 18.2 mos)
- Sarkaria (Wisconsin) noted better 2 year survival than with conventional therapy (class I/II 76% increased to 81%, III 35% to 75% for IV 15% went to 34% and even class V/VI survival increased from 6% to 21%)
- Kondziolka (Pitt) noted survival of 26 mos (51%/2y) for GBM and 32 mos (67%/2y) for anaplastic astro, higher than with conventional therapy
- Nwokedi (Maryland) survival inceased from 13 mos to 25 mos with the addition of a gamma knife boost
What dose to use?
- Pitt after 55-60Gy EBT use marginal dose of 15.5 - 16Gy (in literature 12-20Gy)
- Buatti (UF) 60Gy EBT then 12.5 gy (80% IDL)
- Gaunett (Arizona) 59.4Gy EBT then 10Gy
- Loeffler (Harvard) 59.4Gy EBT then 12Gy (10-20) min and 15Gy (12-25) max
-Mehta (Wisconsin) 54Gy EBT then 10-20Gy min (15-35Gy max)
-Cho (Minnesota) for retreats after EBT used 17Gy (50% IDL)
-Nwokedi (U Maryland) EBT (59.7Gy) then 17Gy (50% IDL) ( diameter pre-EBT of < 4cm, avg volume treated 18.5cc)
-RTOG (90-05 and used in 93-05) 60Gy EBT plus 24Gy (2cm) 18Gy (2.1 -3cm) and 15Gy (3.1-4cm) at margin (50-90% IDL)