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Old 02-15-2009, 09:38 AM   #35
viperfred viperfred is offline
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Join Date: Dec 2008
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Re: The Cyberknife? Has anyone used this form of treatment?

Hi Jim,

Your view is very logical.

The politics and economics are the biggest part of the foundation and fear of this debate by the doctors.

At 1 year the toxicity of radiation will be evident and continue to increase if the treatment has damaged critical structures. If at two years the toxicity results of side effects are lower than 3D-RT/IMRT. There is no science that can explain why there would be an increase in toxicity that causes one treatment to diverge.

Dr. King did not attend the Users Meeting. I will ask Dr. King when he will update his study.

I did discuss toxicity with CK/IMRT/HDR BT Doctors at the meeting. The specific question was if toxicity is low at one or two years is that a predictor of long term toxicity or will toxicity be delayed and not appear for 5 or 10 years. The answer is that toxicity will appear early(3-6 months) and continue to increase or or diminish. It will not be low early and 5 years later diverge.

The cure rate for PCa is a different story because of the growth and development of PCa is very complex and not understood. If failure occurs it is assumed that the local therapy missed a few cells that will continue to grow and will result in failure at some point in the future 2-20 years. I asked how do they know that a treatment failed vs a development of a new cancer? The answer was they could not tell.

CK failure is very very low and no one expects it to stay an near zero at 10 years. They do expect it to be as good or better than HDRT because it duplicates that treatment dose with better control.

When you discuss CK with an IMRT doctor after they explain their fears for CK. Ask them about the studies that show the safety(toxicity) for IMRT at 80-81Gy.

There is a double standard professed IMRT increasing dose is ok but the now extensive data for CK is still in question.

Remember CK has been used for brain tumors for over 10 years, treating tumors that no other treatment can address.

I suggest the tissue surrounding a brain tumor is pretty critical.

If CK or IMRT are not controlled they can be deadly. This a is very serious business.