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Old 12-08-2008, 07:22 PM   #1
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The Cyberknife? Has anyone used this form of treatment?

I was reading about it when I was at work today. What do you all know about it's effectiveness?

 
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Old 12-08-2008, 08:50 PM   #2
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Re: The Cyberknife? Has anyone used this form of treatment?

Quote:
Originally Posted by Trace212 View Post
I was reading about it when I was at work today. What do you all know about it's effectiveness?
Trace,

I just went to our friend PubMed, [url]www.pubmed.gov[/url], a site we can mention here because it is sponsored by the Government, and searched for " prostate cancer AND Cyberknife ".

I got 9 hits - not many for a prostate cancer option - as you would expect for a newly emerging kind of therapy, and the dates of the papers were interesting, showing that knowledge and interest is growing:

2003 - 1
2006 - 1
2007 - 3
2008 - 4

I looked at the abstract of only one paper because that looked the closest to what you were interested in. That 2008 paper gives early results for a Phase II clinical trial, and it's clear there are only a few years (about three) of followup results, which is a very short period. In other words, no one really knows how effective it will be in curing and controling cancer. However, the followup period does seem to me to be long enough to get a good feeling for side effect occurence and seriousness, and the early results look good. If you look over some of those abstracts, I'm sure we all would like to know your impressions.

Because CyberKnife is another form of IMRT, but with far more potential beaming aiming points (think aiming from any point in a sphere in contrast to aiming from any point in a circle), my hunch is that its long term results will be close to those from advanced IMRT.

CyberKnife is getting a big commercial push in my area. It competes, of course, with brachytherapy, IMRT, Tomo-therapy (and similar Trilogy), and proton beam. We are blessed with the curse of many options!

Here's something that puzzles me: external beam radiation, which includes CyberKnife, is divided up into sessions over time to give healthy cells a chance to recover, with the time periods being too short for recovery of cancer cells, which are more sensitive to radiation. Well, CyberKnife sharply reduces the number of sessions, with more radiation delivered in each, at least that's my impression. That isn't consistent with my notion of how the healthy cells tolerate the radiation (in other words, the healthy cells get a pretty hefty dose each session), but the early results for side effects look good, so apparently toleration is good. Maybe more aiming points is key. Anyone got that one figured out? I don't yet know much about CyberKnife.

Jim

 
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Old 12-10-2008, 03:35 PM   #3
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Re: The Cyberknife? Has anyone used this form of treatment?

Quote:
Originally Posted by IADT3since2000 View Post
Trace,

Our Us Too International prostate cancer education and support group had its meeting last night, and by good luck I got some timely information. We had a panel of two - a DaVinci robotic surgeon and a radiation oncologist. Both were somewhat skeptical and concerned about CyberKnife, though they struck me as reasonably objective and not trying to shove it out of the prostate cancer treatment marketplace. I'm inserting some comments in green.

...

Because CyberKnife is another form of IMRT, but with far more potential beaming aiming points (think aiming from any point in a sphere in contrast to aiming from any point in a circle), my hunch is that its long term results will be close to those from advanced IMRT.

The doctors thought the same, more or less: similar effectiveness to IMRT. Even though the delivered dose is about half as much, there is a formula that radiation oncologists use that indicates the impact on cancer will be about the same because the doses are only a day apart and a much higher amount of radiation is delivered in each of the five doses. However, they were quite concerned that there will not be any long term results of cure rates for years - CyberKnife for localized prostate cancer treatment is just too new.
...

Here's something that puzzles me: external beam radiation, which includes CyberKnife, is divided up into sessions over time to give healthy cells a chance to recover, with the time periods being too short for recovery of cancer cells, which are more sensitive to radiation. Well, CyberKnife sharply reduces the number of sessions, with more radiation delivered in each, at least that's my impression. That isn't consistent with my notion of how the healthy cells tolerate the radiation (in other words, the healthy cells get a pretty hefty dose each session), but the early results for side effects look good, so apparently toleration is good. Maybe more aiming points is key. ...

This is where I'm now really concerned about CyberKnife - the long term side effects. Radiation has two kinds of side effects, one, referred to as "acute," develops fairly quickly and then goes away. Another kind takes a while to develop, often several years, but then may stay, including such complications as scaring, fibrosis, and strictures. The studies that have been done with CyberKnife for prostate cancer are short, with the longest having about three years of followup according to our speaker (and what I looked at on [url]www.pubmed.gov[/url]). That's long enough to assess success with short-term side effects, and CyberKnife is doing well on those. However, the doctor said that heavy dosing during individual radiation sessions - the pattern for CyberKnife use, does not affect short-term side effects much, but such heavy dosing is known, based on work with other forms of radiation, to affect long-term side effects. The doctor confirmed that there just has not been long enough followup to know what CyberKnife will do for long-term side effects. He, as well as the robotic surgeon on the panel, were quite concerned, and the long-term risk sure looked like a huge and risky unknown to me also. The doctors felt that CyberKnife was best used in a clinical trial setting, where results would contribute to knowledge. They discouraged other use though, feeling that CyberKnife for local prostate cancer treatment was "experimental at best."

(Coincidentally at the meeting, one of my buddies described a long-term side effect from brachytherapy several years ago that he had recently developed.)

Here's some more technical information about the way CyberKnife is used. While it could be used like current equipment that spreads small doses over many weeks, it is being used and marketed as a quick kind of external beam radiation therapy, the kind you can complete in just five sessions during a single week. There is a name for the dosing and timing used in this approach: Stereotactic Body Radiation Therapy; instead of a standard external beam dose of about 1.8 Gray (radiation units) delivered in 43 sessions for a total dose of 77.4 Gray, spread out over about eight to nine weeks with weekends off, Stereotactic Body Radiation Therapy delivers five doses of 7.25 Gray each within one week for a total dose of about 36.25 Gray. Other types of radiation equipment have also been used to deliver this kind of therapy.

While the new comments are negative, it is always wise to hear the other side before drawing conclusions. I hope we will hear from someone who can defend CyberKnife. A couple of things are clearly in its favor: it is both noninvasive and takes only one week to deliver.

Jim


 
Old 12-11-2008, 01:52 PM   #4
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Re: The Cyberknife? Has anyone used this form of treatment?

Cyberknife is another term for what has come to be known as stereotactic radiotherapy. It was originally used as a highly targeted radiation treatment for certain cancers and brain metastases because it could be delivered very accurately in lower dosages to very small tumors and areas of brain metastases without damage to surrounding tissue. It is considered a palliative rather than curative therapy.
It is also a much quicker course of treatment requiring fewer visits than the many weeks required for IMRT. It also has fewer and milder if any side effects It is now being used in a few specialty clinics to treat prostate cancer and was performed this year on a lifelong friend of mine who is 76 and too compromised with other serious health problems to risk undergoing any of the more rigorous first line therapies. While it has some effectiveness in retarding the progress of prostate cancer, perhaps long enough to permit my friend to die of other causes, most experts don't consider the dosage of radiation delivered to the prostate tumor(s) high enough to effect a cure. In my friends case it reduced his PSA from 6.5 to 0.8 which is not considered an optimal level following radiation for PCa.

Last edited by shs50; 12-11-2008 at 02:05 PM.

 
Old 12-29-2008, 12:27 AM   #5
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Re: The Cyberknife? Has anyone used this form of treatment?

I am a prostate cancer patient treated with the CyberKnife and a prostate cancer advocate. I am also a founder of ZERO the Project to End Prostate Cancer.
I was diagnosed with prostate cancer (PCa) in Aug. of 2007. My PSA was 4.0 ng/ml, a transrectal ultrasound-guided biopsy revealed a stage T1c adenocarcinoma involving the right mid to right apex with a Gleason score of 3+3; in 3 of 12 cores.
I discussed all treatment options with my family doctor, doctors at Stanford, Surgeons and Radiation Oncologists. I reviewed all options with my wife. As a father of a nine year old son, Business owner, treatment recovery time was an important consideration. I have a clogged artery which made the risk of surgery higher than I was willing to consider.
I selected SBRT/CyberKnife treatment option for prostate cancer at Stanford. Their clinical trial data, started Dec. 2003, was very encouraging with ZERO biological failures and minimal side effects (my research suggested the CyberKnife is at least as effective as IMRT). My CyberKnife treatment was five days of one hour sessions with no recovery time (IMRT is five days per week for eight weeks). I was advised of and understand the long term risk of radiation side effects and felt the advantages of SBRT/CyberKnife treatment far out weighted the long term risk.
I completed CyberKnife treatment (May 7, 2008) by Dr. Christopher King. Fourteen days post CK treatment there were minimal side effects. I continued to work every day during and after treatment.
It is now over six months post CyberKnife treatment. I am 110% of pretreatment base line for all related functions. The plus 10% is from improved urinations. Before treatment I would get up 3-4 times a night now I typically get up once. My PSA at the six month follow up was 1.09 ng/ml. SBRT/CyberKnife has treated my prostate cancer and has improved my quality of life.

The CyberKnife is the best treatment option for localized prostate cancer with a cure rate at least as good as any other option and few side effects no worse than any other treatment.

 
Old 12-29-2008, 09:18 AM   #6
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Re: The Cyberknife? Has anyone used this form of treatment?

Quote:
Originally Posted by viperfred View Post
I am a prostate cancer patient treated with the CyberKnife and a prostate cancer advocate.
...
The CyberKnife is the best treatment option for localized prostate cancer with a cure rate at least as good as any other option and few side effects no worse than any other treatment.
Your summary was very interesting- I completed proton therapy treatment a little more than a year ago after doing quite a bit of research. I admit that I did not study cyberknife, but based on the reading I've done since your posting on this board, I'm not sure I would have been a good candidate.

With the proton beam as well as other external radiation, there is the ability to radiate the entire prostate, and even a small margin beyond the prostate, depending on each individual's need, to treat the edge of the capsule and slightly beyond. With proton, there is no exit dose of radiation, and that's why side effects are reduced substantially. I think that's something that's a big "pro" for proton beam radiation vs surgery-- some people seem to minimize the likelihood, even though low, that the margins may be positive after surgery and will therefore require radiation afterwards (and if that's a possibility, why not just have the radiation to begin with-- reduces the risk of potentially serious incontinence and ED side effects of surgery).

It seems that the Cyberknife is best with a very defined tumor, and the idea of a high dose to the prostate does make sense (but I think total delivered radiation is about half the 78 Gy. that I received). But how does the entire prostate get effectively reached and treated? Is this indicated more for those with a relatively low Gleason score, like 6? Is there a preferred minimum age for treating people with the Cyberknife? What is considered an acceptable nadir for PSA say
one to two years after treatment?

Given the high dose/day to the area being treated, just how is the radiation controlled upon exiting the body? Is there no exposure dose after its energy is dissipated as with protons?

This certainly is an interesting treatment though, and the time commitment is obviously much less than with protons or IMRT (my "vacation" in Jacksonville lasted for a couple months)-- but I haven't come across good support for the claim that the cure rate is at least as good as with other options. The lack of long-term apples-to-apples studies is about the only way to make that determination I would think.

 
Old 12-29-2008, 11:28 AM   #7
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Re: The Cyberknife? Has anyone used this form of treatment?

Quote:
Originally Posted by viperfred View Post
...The CyberKnife is the best treatment option for localized prostate cancer with a cure rate at least as good as any other option and few side effects no worse than any other treatment.
Hi again Fred,

Now that we have two threads on CyberKnife going simultaneously, it's getting more difficult to know what has been covered in each thread, but I want to add to concerns that daff raised, which I'm hopeful you may be able to address.

As a now savvy (once very ignorant!) veteran of prostate cancer, just at the nine year survival point for a challenging case (baseline PSA 113.6, etc.), I've watched the data slowly emerge that indicated that external beam radiation and seeds were at least as good as surgery (including proton beam I think - maybe daff can help) . A key result we waited for was how men would do at the ten year point, and in late 1999 when I was diagnosed, no such studies had been published (and would not be for a few more years). Now we have not only that data but additional data with more years, especially from Dr. Michael Dattoli, that is very encouraging .

Are you aware of any published data on more than about three years average follow-up for CyberKnife? While the three years results for CyberKnife are excellent, survival for ANY kind of treatment (including active surveillance) for prostate cancer is now around 99% for most kinds of patients, so I'm at a loss to see that just three years tells us much. I'm personally encouraged by the subtle details of the three year results for CyberKnife, but I would personally not place a large bet (like my life) on those three year results, given the very well documented results for many other approaches with ten years or more of follow-up. That said, I'm grateful to you and other pioneers who are having this therapy and benefiting others with your experience, both good and bad!

After reading the abstract of Dr. King's 2008 clinical trial paper and having had a night to sleep on it, I am very concerned about the 38% he reported with severe rectal toxicity for those men treated over just five straight days with no rest in between!

It is good to learn that the remaining 62%, men like yourself, avoided such toxicity, but 38% is a far, far higher number than experienced these days for established kinds of radiation such as IMRT, seeds and proton beam. The book "A Primer on Prostate Cancer - The Empowered Patient's Guide" (Strum and Pogliano) addresses radiation toxicity on pages 116 - 118, as well as on pages B16-B17. Generally these days, IMRT, as one leading form of radiation therapy, is delivered at a dose range of from 75 to 81 Gy, and the three year actuarially projected rectal toxicity is only 2% (versus 20% for 3D Conformal Radiation Therapy, an older method), per one respected study. Also, reading between the lines, it appears that virtually none of that toxicity was severe, in sharp contrast to the results of 38% severe rectal toxicity for Stereotactic Body Radiotherapy (SBRT), with which CyberKnife is closely associated, reported recently by Dr. King.

I remain highly impressed that allowing a day of rest between SBRT CyberKnife sessions reduced the nearly three year rectal severe toxicity to 0% in Dr. King's study, but I have an impression that CyberKnife is being pitched as a treatment that will be delivered in just five straight days. Because many new patients will be looking at SBRT with CyberKnife, I'm thinking that one of us should post a thread with a caution in the title about five straight days of SBRT, in light of Dr. King's paper (38% of severe rectal toxicity), with a comment on the ten day alternative. Is there a reason we should not do that?

Also, while nearly three years of interim results on toxicity reported by Dr. King and his colleagues are encouraging , a lot of us would really like to see data for at least five years, hopefully from several respected radiation centers known for their work with prostate cancer. For instance, does anyone know what Memorial Sloan Kettering in New York City and what Fox Chase in Philadelphia are doing with CyberKnife, to name just two of the expert centers that are known for excellence in using a variety of radiation techniques?

I'm wondering if Dr. King has hit on ways that look promising for reducing long term side effects with SBRT. Did he talk about that with you? Did he present skipping a day between sessions as an option?

Again, thanks for your pioneering work with SBRT therapy, and I'm glad you are one of the success stories!

Jim

Last edited by IADT3since2000; 12-30-2008 at 06:43 PM. Reason: Spelling.

 
Old 12-30-2008, 02:01 AM   #8
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Re: The Cyberknife? Has anyone used this form of treatment?

Hi Daff,

First wish you the very best and hope you stay cancer free. Today options are better than 10 years ago.

Regarding Proton therapy, I did look at that option and found it to be no better than IMRT and that is supported by a new study

The CyberKnife has the best control of beam delivery to target the complete Prostate and whatever margin the doctor defines. Side effects from Proton Therapy are no less than the CyberKnife.

There are may who make comments about all options that are not valid.

I spent 7 months researching the CyberKnife in my insurance fight covered
I provided the state of CA hundreds of pages of literature and won the state appeal which forced the insurer to pay. This insurer added SBRT/CyberKnife coverage 2 months later including some of my studies in the rational for covering SBRT/CyberKnife for PCa.

Look at the literature biological failure at 3 years is several percent depending on the doctor and treatment. At five years the failures seem to be very low for all treatments. Ten years is an abritary number which to me is meaning less. If the cancer is in the CyberKnife target it is gone. If it has moved beyond the target and missed by the high dose your PSA will likely rebound at some point. No matter what local treatment is used if the cancer is out side the treatment area the treatment may fail.

One problem with todays Peer Review is the delay in publishing the data. By the time we have access to the data the actual data is a year or more old.

I am excited to get copies of data from the CyberKnife users meeting as I know some of it is as good as Dr. Kings data on 100's of patients.

Treating prostate cancer is big business and there are major struggles to get market share. And a lot of misinformation.

That is why I say trust no one and do your own research.

I do not pull numbers from a hat as some people do. Check the links and Article infor I have provide in my other post.

The good news is we are getting better options and even localized failures can be cured.

Hopefully some day soon a vaccine or magic drug will stop this cancer in its tracks.

Last edited by moderator2; 12-30-2008 at 07:12 AM. Reason: posted disallowed website(s)

 
Old 12-30-2008, 09:16 PM   #9
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Re: The Cyberknife? Has anyone used this form of treatment?

Hi again Fred,

I hope daff will reply, but I'm inserting a few thoughts in green. Jim


Quote:
Originally Posted by viperfred View Post
...The CyberKnife has the best control of beam delivery to target the complete Prostate and whatever margin the doctor defines.

I too see it the way you do, though I haven't seen information showing that the CyberKnife beam delivery system gives it much of an actual, practical advantage over other modern, highly precise systems, such as TOMO therapy, Trilogy, advanced IMRT, and perhaps daff will speak for proton beam. I'm familiar with the same kind of issue involving TOMO therapy and IMRT: clearly TOMO can offer higher precision and faster planning, but the precision advantage is not great because advanced IMRT is already so precise.

My impression is that CyberKnife can beam in radiation from any point in a sphere surrounding the patient, while other advanced systems do it from a circle or perhaps a circular tube. Is that the way it is? I can see where a sphere-ful of delivery points would be a big advantage with some other, non-prostate types of tumors.


Side effects from Proton Therapy are no less than the CyberKnife.

To me it's not CyberKnife that is the main issue for side effects, but rather the SBRT (Stereotactic Body Radiotherapy - where in heck did they ever come up with that moniker? ) dosing that is a key attraction for CyberKnife; in other words, delivering the entire dose over a very short timespan, and in the mode we are hearing about most, with no day of rest between doses. That short, no-rest, high-individual dose SBRT schedule resulted in a worrisome 38% incidence of severe rectal side effects in the study led by Dr. King. I would bet a fair sum that proton beam, using normal accepted dosing schedules for that mode, does far better than that regarding rectal side effects, but I'm hoping daff will comment.

... I spent 7 months researching the CyberKnife in my insurance fight covered
I provided the state of CA hundreds of pages of literature and won the state appeal which forced the insurer to pay. This insurer added SBRT/CyberKnife coverage 2 months later including some of my studies in the rational for covering SBRT/CyberKnife for PCa.

On behalf of all of us, THANK YOU! It often takes extraordinary dedication by patients to produce practical advances in treatments and insurance coverage!

Look at the literature biological failure at 3 years is several percent depending on the doctor and treatment. At five years the failures seem to be very low for all treatments. Ten years is an abritary number which to me is meaning less. ...

I've now been at this for nine years with a cancer considered incurable with today's technology, and I've become familiar with those graphs of survival and treatment failure/recurrence for various treatment options and patient characteristics over extended periods of time. I've become convinced that it is important to look at long periods of time to get a good grasp of what is going on, but of course that is my opinion and you are certainly entitled to your opinion. What I'm often looking for is whether the "curve" of survival or recurrence in a study continues to fall (or climb, depending on the study) or tends to flatten out. For example, if a form of treatment for a certain type of riskier patient results in low recurrence figures that stop increasing and flatten out at, say, the eighth through fifteen year, that's a pretty good indication that the treatment is highly effective and that it will keep being effective beyond the years in the study. On the other hand, if the early recurrence figures are not low and keep increasing as time goes on, that diminishes my enthusiasm. We see too much of that in study results. For my money, I want to see ten years, though often I have to settle for fewer years, and of course more than ten years is nice. Five years, while not helping much for indicating curative success, especially with low-risk patients, apparently is the amount of time needed to fully assess late-onset radiation toxicity.

One problem with todays Peer Review is the delay in publishing the data. By the time we have access to the data the actual data is a year or more old.

Amen! I saw a very nice study for 3D conformal beam radiation therapy a couple of years ago, but by the time of publication, that mode of radiation was almost obsolete, having been replaced by IMRT. Technology is moving so fast that research lags behind.

...

 
Old 12-30-2008, 10:25 PM   #10
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Re: The Cyberknife? Has anyone used this form of treatment?

Hi Jim,

SBRT by the CyberKnife delivers a radiation beam(pattern) with sub-mm accuracy, reported in radiation oncology peer reviewed journal (Int J Radiation Oncology Biology Physics - Sept 2008 1st author - D. Djajaputra) This beam accuracy in not possible with IMRT as the prostate moves during treatment and with newer IMRT systems the operator can adjust the table to try and correct the beam to the target. The CyberKnife beam is adjusted before shooting the beam to make sure it is on target.
The prostate moves in three axis as blatter and colon do their job. The technical details are available if you want them. I have not figured what links are ok and what are not ok so I will let you figure out how to get the info.

The CyberKnife can deliver a beam form 1200 angles and in PCa the number of angles the plan uses approx 175. This is a key benefit to reduce dose to normal tissue. This is not possible with the other radiations sources mentioned.

Historical data is a mixed bag as the classification of PCa was poor compared to today.

For cure the slope of the graph is the most important thing to me as I have found no graph in the history for any treatment that diverges from its early(1-3 yrs) path.
In simple terms if the failure at 3 years for study "A" is 3% and for study "B" 0.1% at 20 years study B will not be worse than "A". The absolute number of ten years is nice but of little practical value.

 
Old 12-31-2008, 04:29 AM   #11
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Re: The Cyberknife? Has anyone used this form of treatment?

Quote:
Originally Posted by IADT3since2000 View Post
...
I hope daff will reply, but I'm inserting a few thoughts.
...
I don't really have much to add, since I do not know enough about Cyberknife to try to compare its side effects with those after proton beam radiation. I can
say that from what I've read, talked about, and experienced, that I believe side effects from proton beam radiation are less severe overall than with other forms of treatment. Maybe Cyberknife is the magic cure, but I don't think enough is known yet.

 
Old 01-02-2009, 07:27 AM   #12
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Re: The Cyberknife? Has anyone used this form of treatment?

Go to the mfr. web site and look at the technology.

IMRT delivers the dose from a fixed gantery 5-7 angles of radiation source. The CyberKnife delivers the dose in 175-200 angles. Good tissue see less radiation with the CyberKnife. The lower total dose also favors lower risk of secondary cancers.

The reason the total dose can be lower is that PCa is killed faster with more energy per dose. Good cells are more resistant to this higher dose. This is discussed in Dr. Christorpher King's Papers(2003, 2008) which can be found at pubmed.

 
Old 01-02-2009, 11:08 AM   #13
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Re: The Cyberknife? Has anyone used this form of treatment?

Hi Fred,

I'm putting some comments in green. I really appreciate that you are giving us a lot to learn and think about for this new therapy. I'm going to try to find some time to read some of the original sources.


Quote:
Originally Posted by viperfred View Post
...

IMRT delivers the dose from a fixed gantery 5-7 angles of radiation source.

My impression is that the 5 to 7 angles was so for the old types of radiation therapy, perhaps including 3D conformal beam therapy. But I'm fairly sure that IMRT allows far more angles - basically from any point in a circle, or perhaps a tube type environment surrounding the patient - but not from the ends of the tube, not from the points of a sphere, which CyberKnife can do. I'm going to try to research and resolve that, but maybe one of the proton or IMRT survivors can help.

The CyberKnife delivers the dose in 175-200 angles. Good tissue see less radiation with the CyberKnife.

I accept that - believable to me. What I'm wondering about is how much advantage that is compared to modern IMRT (including Tomo Therapy and Trilogy machines). I have learned that our physical makeup in the pelvis limits some of the angles that can be used by any external radiation machine, unless you want a lot of energy going through organs and bones that are undesired as targets, such as the rectum and bladder. In fact, there is some concern about proton beam energy and the hips, but apparently it is not a major issue. So I'm wondering how many additional angles are practical therapeutic angles.

I've learned from your comments that CyberKnife can achieve sub-millimeter accuracy. That is superb! But again, I'm trying to figure out how much of an advantage that is compared to the accuracy now possible even with IMRT set-ups, not counting TOMO or Trilogy. Dr. Michael Dattoli, MD, a top flight physician and researcher specializing in prostate cancer, also known as a highly respected educator of both physicians and patients, can achieve accuracy to 1 millimeter, the equivalent of the width of a few playing cards, as I recall his talks (could not find my notes on that, but I'm fairly sure that's correct). However, Dr. Dattoli is an acknowledged top expert, and I'm not sure how well other radiation therapists would do in achieving such accuracy nor how that would compare with the accuracy of doctors now learning how to use CyberKnife equpment for prostate cancer. Dr. Dattoli is reporting superb cure and control rates as well as fine rates for avoidance of significant side effect with his approaches, which often involve adding seeds following advanced IMRT. On the downside for his approach, the usual commitment of well over a month for IMRT sessions is required unless he uses just seeds.


The lower total dose also favors lower risk of secondary cancers.

I've been trying to get a handle on the percentage of secondary cancers from radiation for prostate cancer for a while now, but I still only have an impression, and my impression is that the percentage is very low and that any such cancers take many years before they appear. Part of my problem is there seems to be little research on that. Another problem is that the technology keeps changing: higher external beam doses are now being used - often 75 to 81 Gy for IMRT instead of around 64 to 70 Gy, and additional radiation is being used to aim the beams (real time CT scanning for instance with TOMO therapy). It's possible this additional radiation might cause problems, and it will almost certainly be many years before they develop, making them hard to spot so that a link to radiation techniques can be determined. Maybe you or another board participant knows more about specific research on secondary radiation.

The reason the total dose can be lower is that PCa is killed faster with more energy per dose. Good cells are more resistant to this higher dose. This is discussed in Dr. Christorpher King's Papers(2003, 2008) which can be found at pubmed.
Thanks for spotlighting these key papers. I hope to follow up reading the abstracts of these by reading the full texts in my hospital's medical library, where they welcome patients.

I'm thinking that CyberKnife is able to lower the late-onset rectal side effects you would otherwise expect from the high individual session doses with Stereotactic Body Radiotherapy (SBRT) by achieving a favorable tradeoff between superb cancer targetting on the one hand with a dose that could cause long-term rectal toxicity on the other. Also, the approach of a day of rest between SBRT CyberKnife sessions - the superior approach in the Dr. King paper that brought those severe rectal side effects from a disturbingly high 38% to 0%, actually gives more rest between sessions than IMRT, for instance, where five daily sessions are followed by the weekend off.

I'm also thinking that I sure would not want to run the gauntlet you did with five straight daily sessons. I would be only to happy to settle for just one more week of therapy in order to bring down the risk of late severe rectal symptoms from 38% to 0%. Maybe the upcoming February workshop will reveal a way the one week program can be done with low risk instead of that 38% risk.

Thanks for helping us face this new therapy option and think!

Jim

 
Old 01-03-2009, 07:08 PM   #14
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Re: The Cyberknife? Has anyone used this form of treatment?

Hi Jim,

More angles = less exposure of radiation to normal tissue.

Accuracy = less target margin = less collateral damage to surrounding tissue.

The CyberKnife target accuracy and prostate real time tracking are unmatched = max. dose to target and min. dose to surrounding structures.

My CyberKnife treatment was M, W, F, M and W.

If you want to know about the CyberKnife vs IMRT and HDR Brachytherapy Contact experts who have and or are using these options for prostate cancer. Doctor Donald Fuller provides these options to his patients and has published papers on the CyberKnife. He is a radiation oncologist expert for all RT options. Others Experts (all provided information to have my insurance denial overturned) offering IMRT and CyberKnife are Doctors Christopher King, Alan Katz, and Clinton Medbery III. A radiation oncologist that is an IMRT expert, is not and expert on Brachytherpy or the CyberKnife. Each treatment has procedure training that is specific to the technology. Combined training and experience for each treatment make an expert.

Some "experts" express concern about the high dose per session from the CyberKnife and the unknown side effects. For some unknown reason the 10 plus solid data from HDR Brachytherapy is ignored? HDR BT dose is given in two to three days with one day of rest in between treatments. So there is data for this dose rate. And the CyberKnife Data is equal to or better than HDR BT.

Proton Therapy is no better than IMRT per ASTRO 2008 meeting, IMRT has not been proven to be better than 3D-RT per CTAF 2007.

Patients need to do their own research and trust no one including me.

 
Old 01-07-2009, 12:05 PM   #15
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Re: The Cyberknife? Has anyone used this form of treatment?

Hi Fred,

I'm continuing our discussion with some comments in green. Jim


Quote:
Originally Posted by viperfred View Post
...Some "experts" express concern about the high dose per session from the CyberKnife and the unknown side effects. For some unknown reason the 10 plus solid data from HDR Brachytherapy is ignored? HDR BT dose is given in two to three days with one day of rest in between treatments. So there is data for this dose rate.

But there is a major difference, and it may or may not prove critical: High Dose Radiation Brachytherapy is delivered with seeds that are inside the prostate, and their placement is designed to minimize radiation to other body parts, such as the rectum; in contrast, some CyberKnife radiation must pass through the rectum to get to the prostate, and it is at a high enough dose that it caused problems for a substantial percentage of men in one of Dr. King's papers. That's why the same dose rate for HDR brachy may have a much more benign impact on the rectum than if delivered by CyberKnife (or any other external system).

Here is a key result that I think serves for a fair apples-to-apples type comparison with the King paper from one study of what I think is HDR brachytherapy, since I was using an HDR brachytherapy search string:
"... The freedom rate from Grade 2 or higher rectal bleeding at 5 years was 88.5%. " Basically, that means that less than 12% of patients at the five year point had moderate or severe rectal bleeding due to radiation. That is far lower than the 38% severe rectal toxicity reported in the King paper for patients who were treated on five straight days with CyberKnife. (Grade 2 is a moderate level of rectal side effect, "Moderate diarrhea and colic; Bowel movement > [greater than] 5 times daily; Excessive rectal mucus or intermittent bleeding." Grade 3 is "Obstruction or bleeding requiring surgery; Grade 4 is Necrosis, Perforation or Fistula. (The grade descriptions are on page 116, Table 8: Chronic Gastrointestinal (GI) Toxicity/Radiation Therapy Oncology Group (RTOG) Grading System, "A Primer on Prostate Cancer - The Empowered Patient's Guide.") The quotation is from the [url]www.pubmed.gov[/url] abstract for "International Journal of Radiation, Oncology, Biology and Physics.2008 Jan 1;70(1):96-101. Epub 2007 Nov 5. (125)I monotherapy using D90 implant doses of 180 Gy or greater. Kao J, Stone NN, Lvaf A, Dumane V, Cesaretti JA, Stock RG.


And the CyberKnife Data is equal to or better than HDR BT.

Proton Therapy is no better than IMRT per ASTRO 2008 meeting,

Would you mind providing more detail on the reference and any more detail you can give, as context is often important? I've read similar comments from Dr. Michael Dattoli, a world leader in IMRT and seed therapy for prostate cancer, but he is obviously in competition with proton beam therapy, especially as he practices in Sarasota, Florida and there is the fairly new proton facility in the same state at Jacksonville that daff knows so well.

In thinking about this, I looked at published information from ASTRO, now the American Association for Radiation Oncology (name changed yesterday, but keeping the abbreviation with the T in the middle), and I discovered that ASTRO is hosting a conference in Arizona in the latter days of this month entitled: "Practical Aspects on IMRT and Proton Therapy Symposium." Hopefully the docs will throw some light on the proton versus IMRT issue, but there may be some sharp elbows flying.


IMRT has not been proven to be better than 3D-RT per CTAF 2007.

Would you mind also providing more detail on the CTAF 2007 reference? I could not find it in a [url]www.pubmed.gov[/url] search, and I found no such statement in an abstract when I broadened the search. Is the source a poster abstract from the ASTRO 2008 conference (which would not be in PubMed)? I'm surprised by the statement as so many abstracts I've read and talks I've heard document substantial superiority of IMRT over 3D-conformal radiation for prostate cancer. I believe that is now the consensus view of experts, but I don't follow radiation closely enough to be certain.

Take care,

Jim


...

Last edited by IADT3since2000; 01-07-2009 at 04:21 PM. Reason: Spelling: conformal

 
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