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Old 02-13-2009, 11:05 AM   #31
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Re: The Cyberknife? Has anyone used this form of treatment?

Quote:
Originally Posted by viperfred View Post
... The CyberKnife is very quickly becoming the standard of care across the US. IMRT.... was on a big growth curve driven by prostate cancer. That is now slowing and those newly invested in IMRT are saying there is not enough data or time. ....
Fred,

I can only give you my impressions from the viewpoint of what I am hearing in support group, education and advocacy circles and in research circles, as I understand it. Based on that, it looks like something different is occuring.

First, I know you are eager to declare CyberKnife with Stereotactic Body Radiotherapy dosing (CK SBRT) a standard of care, but my impression is that virtually all doctors would be unwilling to do that at this time, and I'm confident that neither Dr. King nor Dr. Fuller would want to do it either. Just be patient - I think it will get there. And, it does not have to be considered a standard of care to be widely used and reimbursed, though obviously reimbursement via insurance will be easier for many of us if it is so recognized.

Also, though it is wonderful to learn that a growing number of patients are now feeling comfortable in choosing CK SBRT, if only a couple of thousand have done so in recent years, then the percentage choosing that therapy is really tiny considering that more than 200,000 men in the United States are diagnosed with prostate cancer each year; obviously, they are choosing other approaches. I'm confident that percentage will grow with the good work you and others are doing in bringing this option to the forefront.

Second, regarding IMRT, my impression is that regular dose brachytherapy was the approach on the bigger growth curve rather than IMRT, but also that data for both IMRT and brachy are now considered fairly long and adequate, though we would always like to see more data.

For instance, knowing that Dr. Michael Dattoli, MD, is a leader in brachytherapy and IMRT who has recently published long term results, I went to [url]www.pubmed.gov[/url] with this search string: " dattoli m [au] AND prostate cancer " and got ten hits. Here's one key paper:
"Long-term outcomes after treatment with brachytherapy and supplemental conformal radiation for prostate cancer patients having intermediate and high risk features." Dattoli M, Wallner K, True L, Cash J, Sorace R. Cancer. 2007 Aug 1;110(3):551-5.

The non-failing followup period averaged ("median") 9.5 years, giving capability to project to 14 years, and here are key sentences from the results section: "... Overall actuarial freedom from biochemical progression at 14 years was 81%, including 87% and 72% having intermediate and high-risk disease, respectively. Absolute risk of failure decreased progressively, falling to 1% beyond 6 years after treatment. ..." I've seen some of Dr. Dattoli's recurrence free survival tables for such patients, and it is striking how the recurrence line flattens out - meaning virtually no more recurrences if you have success for the first few years. These are truly stunning statistics for the risk groups he was treating. (By the way, for anyone who wants more detail, PubMed links you to the full paper for free in this case.) (As we would expect, Dr. Dattoli's results for low risk patients, which are not the subject of this paper, are extremely good!)

Finally, I have a strong impression that robotic surgery is replacing conventional radical prostatectomy, and I have a hunch that this is partly rebuilding the percentage of patients choosing surgery as an option. Until the advent of widely available laparoscopic and robotic surgery, in recent years it appeared that many men were concluding the value of dealing with a small risk of uncontrollable prostate cancer with surgery was not worth the likelihood of a substantial side effect and complication burden; now that burden is being lightened.

I wasn't able to find a PubMed search string that gave hard data on any recent statistics for the percentages of patients choosing various therapies. Perhaps others will have better luck.

Fred, if you have hard figures for recent years for the numbers and percentages of men choosing various prostate cancer treatments by year, I would like to learn about them.

Here's a last thought. I'm impressed with the case you are making for CK SBRT on its own merits, and I'm thinking your energy will probably have a bigger payoff there than in the difficult and likely self-defeating task of attacking other therapies, most of which are established or are emerging as pretty decent options.

Jim

 
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Old 02-14-2009, 06:26 AM   #32
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Re: The Cyberknife? Has anyone used this form of treatment?

ALBCMB,

I will have them copied and converted to a PDF, next week. Then need to figure out how to get them to you?

 
Old 02-14-2009, 07:30 AM   #33
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Re: The Cyberknife? Has anyone used this form of treatment?

Hi Jim,

It is impossible to show 10 or 12 or 14 year data before when a treatment is only been used for 5 years with zero failures from the first study. 81% free of PCa at 14 years is relatively good. I do not know the failure rate by year from this study and feel that is critical data to compare to other therapies. From memory HDR Brachytherapy Martinez at 8 years is 98% PCa free.

You will not find a MD that has only IMRT suggesting CyberKnife. There are 40 plus MD's that use IMRT and CyberKnife and some also offer Brachytherapy as an option. They offer their patients the option to select the best treatment for them. This is without bias unlike the IMRT only centers.

CK has also been used as a boost for other forms of RT.

Only time will tell what happens in ten years.

There is more to the CyberKnife than cure alone, it is quality of life.
ED
Incontinence
Rectal failure

It was a very easy choice for me I compared ALL options at 3 years and found ZERO to be better than CK with HDR a close second.

With only one to two years of data it is hard to know what will happen in the future with radiation. There is theory of dose delivery to support the treatment but no hard data. Today the data is matching the theory expected, HDR and alpha beta. I believe in physics and todays technology to measure and deliver radiation. It is better today and will continue to improve with time. There is now CK data at 3-5 years and all very good, certainly no worse than any other option along the same time line.

I support treatment choice 100%, it is the patients life, he has to live with the choice.

 
Old 02-14-2009, 10:34 AM   #34
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Re: The Cyberknife? Has anyone used this form of treatment?

Quote:
Originally Posted by viperfred View Post
Hi Jim,

It is impossible to show 10 or 12 or 14 year data before when a treatment is only been used for 5 years with zero failures from the first study....
Personally I'm comfortable with much less followup for effectiveness for CK SBRT, largely because of points you have raised.

What I'm really eager to see is another year or two of data from the King series, which we may have from the recent Users Group Meeting. That would give us four or five years of followup for side effects, and my impression is that the consensus of radiation doctors is that five years is enough to assess the kind, intensity, severity, and frequency of radiation side effects. Four years would be close, especially with favorable data on at least a few patients with five years of followup, which we should also now have.

Yes, there would still be risk that as the years go by that CK SBRT might turn out not to be as effective as we think, and it might also turn out to develop unexpectedly late side effects after four or five years, but to me the odds would be strongly against that.

To me, it gets down to how much risk is too much for the patient in his own view, balanced against the clear advantages that you have discussed.

Jim

 
Old 02-15-2009, 10:38 AM   #35
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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.

 
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