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• A slow growing neoplasm derived from remnants of the primitive notochord. 
• Tend to grow posteriorly to the brainstem without invading it.
• May also grow superiorly towards the optic chiasm.
• Often will have residual after resection.
• Poor sensitivity to conventional 50-60 Gy doses of radiation.

Noel et al.  Neurosurgery December 2004 issue.

The authors reviewed 90 patients who were treated with a combination of high energy photons and protons using the 201-MeV proton beam of the Centre de Protontherapie d’Orsay.   There were 64 Chordomas and 64 Chondrosarcomas. 

There is often residual disease after resection and a relatively poor sensitivity to 50-60 Gy standard doses of radiation.  

Authors decided to explore the control rates using proton therapy.  The general rationale is to take advantage of the “Bragg Peak” of “proton therapy” and attempt dose escalation to deliver a higher dose, making use of the rapid lateral fall-off of dose (approximately 15% per mm) that is associated with proton therapy.

Local control for chondrosarcomas was 80% at 42 months and 50% for chordomas. 

In the multivariate analysis, local control and the gross total volume of tumor excluded from the 95% isodose line were significant prognostic indicators.

The averate GTV was 29 cubic cm.  The GTV excluded from the 90% isodose line was 3 cc.  The GTV excluded from the 95% isodose line was 4.4 cc.

12/16/04 — Joseph Neimat, MD

North Service Report in the “Ether Dome” at 8:00 a.m.