Proton Beam therapy

[Mlamb]

Hi Everyone,

I was wondering if anyone had any experience with proton beam therapy. I had a 3cm Trigeminal schwannoma that was partially removed this past December. My follow up MRI shows the surgeon left behind a 1.5 cm residual in the Meckel's cave area. Now I am looking into my options. I can have gamma knife but it could cause more post treatment issues as could more surgery. I am still not fully recovered from my surgery in December. Almost the entire left side of my face is numb.  my left eye is not only numb but also very uncomfortable. I have a constant sort tugging sensation. Please give me some advice if anyone had gamma knife post surgery or proton therapy and does proton therapy really carry less of a risk of effecting the surrounding nerves and critical structures?

Thanks so much!

[jrhafer]

Hello Mlamb,

I do not know much about Proton Beam except that my wife was at the Mayo Clinic in Rochester Minnesota and we talked about it as an option for her cancer.  The one thing that stood out was that the doctor said there are no side effects, compared to standard radiation.  Not sure how that can happen but if this is true, this is a major break through in radiation treatments.  Mayo has a Proton Beam unit and I know it is very expensive and that not all insurances will pay for it yet.  Still, given the news about it, it is certainly worth looking into.

I was treated for an AN back in 2005 using Cyberknife.  It was a 3 day out-patient procedure.  Very little side-effects other than an increase in tinnitus and my hearing was saved.  May want to also look into this as an option too.

[PaulW]

Proton therapy has lots of limitations and is not the best technology for all tumours.
The trigeminal nerve is right next to the brainstem which means any radiation needs to be very precise, or there is a risk good tissue will be damaged. Proton therapy is not very accurate, +/- 3.0mm
Versus gamma knife at +/- 0.5mm

Proton therapy because of the Bragg peak also puts more radiation at the edge of the tumour and less in the middle... No big deal for many tumours but not good when it's right next to your brainstem.

[Mlamb]

Thank you all got your advice. I am hoping to delay any sort of radiation for another 5 months and if the tumor still seems stable wait another 6 months. I am collecting information in the meantime so that I have options. I would hate to have another surgery, but if I really had to, I would choose Dr. Schwartz at House.  I'm just very afraid of more post surgical side effects most of which are permanent. I had my surgery this past December and almost my entire left side of my face is still numb and my eye just so uncomfortable and it's not even a dryness thing it's because of the nerves having been manipulated. So more surgery could make things worse as can Gamma Knife but after reading your comments it looks like proton might not be much better. I am waiting to hear back from MD Anderson and Mayo clinic to learn more about the possible side effects with proton beam therapy and if it can effectively kill my tumor.

M

[Freelander]

Hi,
Hope all is well. 
I am curious what you found out about proton beam therapy and its side effects.  I am meeting with a doc in Boston next week for the first time, and I believe it is his treatment of choice.   

[Freelander]

Proton Therapy continues to be of interest in the array of options.  I have posted the below in another location, yet it is better placed in this thread, and may be helpful to others considering radiation therapies. 

The most recent research I've stumbled upon states that proton therapy better spares healthy tissue from radiation than does conventional photon therapy.  An excerpt from this 2017 Nature abstract states the same:
https://www.nature.com/nrclinonc/journal/v14/n8/full/nrclinonc.2017.30.html

Also, this article
 http://www.nature.com/news/three-ways-to-make-proton-therapy-affordable-1.22660?WT.mc_id=FBK_NatureNews&sf116491847=1
reinforces the fact that access to the best proton therapy machines are hindered due to high cost.    Lower cost versions may be forthcoming.   The article also shows in simplistic fashion the different ways conventional radiation and protons pass through the body, and states that protons can be stopped at the depth of the tumor and then released.

I met with Dr. Loeffler, MGH raditaion oncologist, earlier this month to talk about whether I might be ready for treatment of any kind. (His advice was to continue to wait and watch -- while that was encouraging, I do intend to ask other docs due to my symptoms and the MRI he had was 6 mos old).  In addition, I asked about the 3 mm range of uncertainty regarding the release of the energy into the tumor, and the notion that 120% of the energy is also released at the periphery.  He said the 3 mm discrepancy was false information.  He seemed to concur with an increase at the periphery though at perhaps 5% more rather than 20% and that effective controls are in place.   He didn't go into much detail on the issue, nor did I ask, as his opinion about my case was to continue to watch and wait.    In addition, due to the relatively smallish size of my AN (10 mm as of 6 mos ago) Dr. Loeffler said either radiation treatment (photon or proton) would be fine.   This may imply some relevance to comments by others that proton beam therapy is better suited to larger (> 2 cm?) tumors.  I really don't know, nor am I a physicist, oncologist or any other medical care professional; just a curious individual dealing with an unwanted condition, like most people here.  I do like the  that proton beam therapy minimizes radiation to healthy tissue.  As time goes on, we will glean even more.

[extropy]

DECT improves proton-therapy
https://physicsworld.com/a/dect-proves-optimal-for-proton-planning/

[PaulW]

Thanks Extropy,
If I read this article correctly range uncertainty is reduced from 5.1mm to 4.1mm
Great technology to improve things, but still makes the beam accurate from +/- 2.505mm to +/- 2.05mm. Add some margin for the machine, patient setup and imaging quality and it nowhere near as accurate as GK or CK with an overall accuracy of +/-0.5mm for GK.
While proton therapy does less harm to distant tissue, it does more harm the area immediately around the tumour.. Sometimes this is inconsequential, potentially making Proton Therapy better than x rays.
But with AN’s there are potentially a lot of nerves touching the tumour which ge5 more radiation than they would with CK or GK