Hello All , I just completed 3 sessions , ( fractions ) 9 grays each day , of Sbrt to the 1 lymph node in pelvic area . My RO is about 90 minutes 1 way . Dr. Hirsch can do the IMRT in 25 sessions at the same place . Or , at an affiliate , partner in group , with Proton Beam about 30 minutes away . Are there advantages to Proton Beam compared to IMRT ?
Proton Beam vs IMRT: Hello All , I just... - Advanced Prostate...
Proton Beam vs IMRT
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There are no known advantages to protons over X-rays. Proton use in salvage is highly experimental.
The Proton radiation would be to the pelvic field only , 25 days . Does that make it any safer than IMRT , or about the same ? Thanks Allen
As I said, "There are no known advantages to protons over X-rays. Proton use in salvage is highly experimental."
"There are no known advantages to protons over X-rays."
And the basis for this comment is? Have you reviewed the literature?
Yes, of course I've reviewed the literature. There are no direct comparisons, but the effectiveness in monadic tests is the same. Look at this:
prostatecancer.news/2016/08...
Don't see how this answers the question. In an observational study, PBT was superior to IMRT with respect to side effects. Randomized clinical trials are also underway.cancer.gov/news-events/canc...
This is NOT a prostate cancer study. I think there is an advantage to protons for pediatric tumors, head and neck, cancers, and maybe a few others. NONE of the patients in the study you cited were treated for prostate cancer. Serious acute side effects, requiring hospitalization, are nowhere near as high for any kind of prostate cancer radiotherapy, photons or protons.
There is a major randomized trial underway at the University of Florida. Results are expected in 2026. Until then, our best evidence is that there is no difference:
clinicaltrials.gov/ct2/show...
But the OP is interested in salvage proton therapy after primary SBRT. While there is no data for proton use in that setting, there is a retrospective "matched-pair" comparative analysis of protons vs IMRT after failed prostatectomy. They found:"treatment modality was not associated with clinician-reported GU/GI toxicities."
acsjournals.onlinelibrary.w...
Salvage proton RT after SBRT is strictly experimental and should only be done as part of a clinical trial.
Dr Rossi at California Protons in CA would disagree with you.
And when Dr Rossi conducts a comparative trial, I may revise my opinion. He hasn't. Why?
Guess you'd have to ask Dr Rossi that question. Having treated over 10,000 patients with protons, possessing an MD degree, serving as medical director at 2 major centers - his opinion differs from yours which is based on your review of literature/studies/ trials. There is no other radiation oncologist that has more proton expertise or experience than Dr. Rossi, perhaps if he presents again at a pcri conference you might have an opportunity to ask your questions of him.
That is like a urologist who does a lot of prostatectomies and thinks that surgery is the only way to go. If he has any comparative outcomes worth looking at, he would publish them in peer-reviewed journals. Note that his opinion is Level 5 evidence, the lowest level. I hope he will draw conclusions from a randomized clinical trial someday (Level 1 evidence).
Clearly, you have your opinion. And a history of bias against protons on this forum, we've debated this in the past. My concern, is that others believe the opinions of laymen without medical training when medical experts disagree.
I’m just reporting facts-what is known and what isn’t known. I have no bias because I have no stake in it- just a desire to find the truth. I would be just as happy to learn that protons are superior, inferior or no difference. If you have some comparative data I haven’t seen, simply post the link. I don’t understand your reluctance to look at actual evidence instead of unsubstantiated opinions. I assure you that every top RO agrees with me.
You do a good job restating facts , that's true. Thank you.
However, when you state "I assure you that every top RO agrees with me", that is your unsubstantiated opinion.
No point in kicking a dead horse again with you. You have no personal experience with protons, I do. You likely have not discussed the advantages of proton vs photon face to face on a real life specific case basis including discussing dosimetry plans with an RO that offers both proton and photon treatment, I have. You have your opinions which I have no time or desire to debate further as so often happens when others disagree with you.
Respectfully we disagree, and if there are those on this forum considering protons as an option I'm always available as a resource for them which I've been for many over the past 10 years through forums, direct contact, serving as facilitator for a cancer center's support group, and speaking to groups at USC, Loma Linda, and others.
That is not just my opinion. The American Society of Radiation Oncologists says this:
"Proton beam therapy for primary treatment of prostate cancer should only be performed within the context of a prospective clinical trial or registry"
astro.org/uploadedFiles/_MA...
You are advocating for a treatment that the consensus of ROs believe should only be done as part of a clinical trial. It is important for patients to understand this instead of taking advice from "true believers."
Allen, you can continue to kick that dead horse by yourself.
Noting that YOU raised the issue with me, it's called "confirmation bias" when one excludes all evidence that does not conform to one's previously held beliefs.
Thanks Allen , that says it all in my opinion .
Proton has depth control which Sbrt really doesn't.
I would imagine that has to have some superior benefits in some situations and not in others.
But there are apparently no clinical studies on this, otherwise Tall Allen would have mentioned them.
I would get second opinions from a Proton Doc, imrt Doc, and SBRT doc, and make sure as get their thinking on this particular issue.
In all professions, there is a place for professional opinion and hard earned intuition, even when hard data is missing.
Every situation is different. I would not settle for being treated solely out of a standard of care cook book.
"Proton has depth control which Sbrt really doesn't." Nonsense.
My understanding has always been that the protons can be targetted for a certain depth. I never explored or investigated it much further. I had always assumed it was done by varying their energy levels.
But a 30-second google search seems to support that proposition:
"In principle, proton therapy offers a substantial clinical advantage over the conventional photon therapy. This is because of the unique depth-dose characteristics of protons, which can be exploited to achieve significant reductions in normal tissue doses proximal and distal to the target volume. "
"Protons, accelerated to therapeutic energies ranging from 70 to 250 MeV..."
"Despite the high potential of proton therapy, the clinical evidence supporting the broad use of protons is mixed. It is generally acknowledged that proton therapy is safe, effective and recommended for many types of pediatric cancers, ocular melanomas, chordomas and chondrosarcomas. Although promising results have been and continue to be reported for many other types of cancers, they are based on small studies. Considering the high cost or establishing and operating proton therapy centers, questions have been raised about their cost effectiveness. General consensus is that there is a need to conduct randomized trials and/or collect outcomes data in multi-institutional registries to unequivocally demonstrate the advantage of protons."
ncbi.nlm.nih.gov/pmc/articl...
Lack of data, means lack of data. That is the point where getting multiple second opinions relying on the clinical experience of Docs seems to make a great deal of sense to me.
And I believe no one contests that proton therapy doesn't work.
And I find it implausible to not believe that the "unique depth-dose characteristics" of proton therapy can't be used to advantage for certain tumors in particular locations. And it will be a long time coming before proper trials on that can be conducted. How would you even conduct such trials?
Anything you can do with radiation, you can do with protons, except it appears to have one more dimension of control that radiation does not have, depth.
Both authors seem to be well published.
It would seem at the very least protons should be able to deliver the same amount of radiation dose as Xrays, with way way way less dose delivered to non-cancerous tissues.
This may or may not affect the effectiveness of treatment, but it has to have a positive effect in other ways, in other matters, such as secondary cancers that could occur in younger patients years hence. Nothing good ever comes from dumping extra radiation into healthy tissues.
This article even has an interesting chart comparing how much of a dose 200 Mev protons dump at various penetration depths compared to that of 16 MV xrays. There appears to be a very very substantial difference.
It's a shocking difference actually.
I will try to insert that chart here (otherwise refer to the article):
ncbi.nlm.nih.gov/core/lw/2....
ncbi.nlm.nih.gov/core/lw/2....
Since 6 MV & 11 MV linear accelerators became SOC for delivering X-rays in the 1990s, there is no problem with delivering X-rays to any location at any depth in the body. Prostate is about as deep as it gets. Coverage of the entire prostate with the full dose is routine. In fact, that is exactly how physicists program the dose. They generate what is called "isodose curves" to ensure that all of the planned target volume (PTV) - the prostate + a planned margin around it - gets at least the targeted dose. You can see it in the attached illustration. The prostate+a small margin (in red) received 105% of the target dose (of 40 Gy, in this case):
radonc.ucla.edu/workfiles/S...
Exactly the same kind of planning is done for protons or photons.
But don't proton beams have no less an ability to stereoscopically dose a tumor?
I think they do.
What they can do is to target a depth, and avoid dropping a dose on the way in and on the way out.
When I was getting my radiation treatment to my prostate, that beam certainly seemed to be penetrating a lot of good tissue on the way in or on the way out.
If you can avoid or reduce that, while delivering the same dose to the tumor how can that not be a good thing.
And the tumor can be not only in the prostate but perhaps in the spine or some other delicate place.
But no matter what, isn't dosing stereotactically with depth control over dosing better than just stereotactic dosing with incidental dosing of good tissue on entry and exit.
There is no acceptable level of radiation.
That chart is sort of hard to ignore.
I never said it was inferior. So far, it seems to be about the same.
What you think may or may not "be a good thing" is only decidable by a clinical trial. The proof of what constitutes a "good thing" is patient-evaluated side effects, not what you or I think. So far, side effects seem to be very similar. Look at the table in this:
prostatecancer.news/2016/08...
Or this case-matched study:
prostatecancer.news/2016/08...
The "Bragg peak" is a theoretical framework. In clinical practice, it doesn't work that way. There is production of secondary ions from nuclear reactions past the beam. Toxic secondary neutrons are created. Diffraction effects occur at the nozzle and proton-proton repulsion act to spread out the beam, while X-rays, which are not charged particles, remain collimated. Also, proton therapy often requires the use of spread-out Bragg peaks to treat large-sized volumes like the prostate, and especially the entire pelvic LN area. This compromises the tissue-sparing advantage of the sharp Bragg peak.
The Dose-Volume histogram show radiation to organs at risk with protons just is it does with X-rays.
1. Very nice articles on Prostatecancer.news, as always.
2. Those are 5 year studies that you cite.
3. Yes, I guess the in practice fuzziness of the Bragg peak is an issue, I forgot all about that.
"The Dose-Volume histogram show radiation to organs at risk with protons just is it does with X-rays."
If that is true for the healthy tissue in front and behind the tumor, then yes, you won't be reducing the dose burden with protons.
Are you referring to the dosing of healthy surrounding tissue using current techniques for both x-rays & Protons?
If so that pretty much settles this matter. Doesn't it. If not, then perhaps not.
4. Those studies you cite were 5 year studies. I would expect many of the adverse effects of dosing of healthy tissue not to show up until much later than 5 years, perhaps in the form of secondary cancer or early organ failure.
5. Most of these issues, other than the Bragg diffusion, are not easily subject to clear determination by clinical trials, it would seem to me.
For example how do you measure early organ failure or other similar injury to healthy tissue. And how do you measure at 5 years, secondary cancers that might not show up for years later.
It can be done, but it's not easy and that same energy will likely find its way to others research.
6. It's not my decision at this point. I had my radiation treatment.
But if I were going for radiation treatment today, I think I would write down these issues and get some second opinions, informed by daily practice from proton, imrt and Sbrt radiation docs.
7. I think those articles from Prostatecancer.news are about 8 years old.
I did notice one of your charts indicated that, at that time, imrt treatment seemed to be superior to Sbrt treatment for high risk patients.
Has the data changed since then? I was expecting Sbrt to win that race.
There is no more recent data. There is no data with longer follow-up using modern delivery methods. There was a longer term proton study from Loma Linda that had awful results, but methods have improved since then.
It's actually quite easy to find out what the toxicity is to treated patients - you ask them. The EPIC questionnaire is usually used for the purpose.
As for secondary cancers caused by RT, there is agreement that the incidence is very low. There is no data for protons, but the data for SBRT proves it is negligible as far as anyone can tell.
Thanks
Proton tx with pencil beam is more accurate imaging, less side effects than imrt.safer,wiser choice .ca protons has pencil beam, not all tx centers do, accurate,daily imaging, care for minimizing any side effects.
It may be a matter of where the metastases are, If your metastases are directly abutting some vital organ like a spinal cord you might opt for the most precise modality with the least scatter. Mine were in my thoracic spine (4 of them) and beginning to press on my spinal cord. I opted for proton therapy (pencil beam at California Protons) because of its extreme precision 5 yrs ago. Zero spinal cord,lung,cardiac,or esophagus side effects
You would be best served to direct your question to the doctors providing those services. The physics of each are vastly different, and as such there may be an advantage to one vs the other.
A few videos:youtube.com/watch?v=K4IoSy-...
youtube.com/watch?v=WiJLRMb...
Dr. Scholtz in another video explained why Proton is pushed for PCa treatment. He felt it's primarily not driven by benefits to the patients, it's driven by the need to keep the lights on and pay the mortgage on a horrendously expensive facility.
Proton is excellent and superior for other cancer tumors such as pediatric brain cancer, or any tumor on another organ where the organ would be damaged by IMRT. He said it hasn't been shown to be superior, especially for high-risk PCa to "standard" IMRT/IGRT for the prostate cancer patient.
Why use it? In other to keep the lights on the proton facilities need a large pool of people to treat who pay for the facility. The PCa community fits that bill perfectly for the proton organizations due to the sheer number of us who need some sort of radiation treatment.
1. "it's driven by the need to keep the lights on and pay the mortgage on a horrendously expensive facility."
That pretty much drives all radiation facilities. One of my concerns when I was treated, was how frequently the clinic was buying the best and newest equipment.
2. "Proton is excellent and superior for other cancer tumors such as pediatric brain cancer, or any tumor on another organ where the organ would be damaged by IMRT."
Either proton therapy is more precise than x-rays or not.
Scholtz says it is. Tall Allen says not.
Lol, l sort of trust Tall Allen on this a bit more than Scholtz.
But that's why you go get second opinions and ask questions. Isn't it?
So Mr. Spock (a/k/a S'chn T'gai Spock) what do you have to say about the subject?
"Insufficient facts always invite danger."
And what about your ears?
"Humans smile with so little provocation."
And what did your doctor have to say?
"Show me the money!" -
Thank you Mr. Spock, for you participation.
Good Luck, Good Health and Good Humor.
j-o-h-n Saturday 01/15/2022 6:01 PM EST
"Take over Mr. Spook. If you need me, I'll be in the bathroom." "In the bathroom? I don't believe my ears!" Captain Kook, "I don't believe your ears either Mr. Spook!" (Mad Magazine 1967)
Maybe this helps! youtube.com/watch?v=WiJLRMb...
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