questions about proton beams

Spoke with some one from the radio oncology dept @ Mass General about proton beam therapy...

* this therapy is typicall done After standard and only if lesions are small and well seen. Usually best on irregular shaped tumors
* What facilities are doing this procedure? Mass General, Loma Linda, Indianapolis
* Is it appropriate for glioblastoma multiforme IV? Yes, but after a good resection and usually standard treatment.
* Are there other types of stereotactic radiation that would be appropriate? Depends on number of lesions and if the are easy to get or not.
* This is a particle beam vs photon beams gamma/xrays, what is the advantage? Tumors that are irregularly shaped, soft tissue in brain spinal cord in children. Heavier particle, moves at slower energy, not as much dose gets scattered around. Beam more controlled.
* What is the treatment time? 1 or 2 treatments? Depends on the lesion, usually a couple of weeks, stereotactic methods (ie gamma knife) are usually only one treatment.
* Is it only done on tumors, cavity, recurrent or upfront? Still relatively new, so carefully choosing who gets this procedure. Resection is first best treatment, then treatment on protocol of trials.
* Can the dosage be limited so that it can be used in a way similar to standard treatment by treating the cavity, the leading edge and a 2-3cm margin? They can design the plan however they want; however, it is really for specific irregular shaped tumors.
* What is the dosage or radiation, is it different than the amount of radiation we'll be getting with standard treatment? Same as standard
* Can it be done again? Depends on which area was originally treated and how high the dose was, may be able to retreat a smaller area.
* Can it be done after standard radiation, instead of standard radtiation or at the same time? In some cases after standard or could be done instead of, but not at the same time.
* What is exit dose? No exit dose
* What are the known risks with this treatment? Radiation necrosis, same as standard.
* What are the risks of radiation necrosis of this treatment? Not known, treatment hasn't been around that long to have long-term results.
* What are the known benefits of this treatment? Less healthy tissue effected.
* Shouldn't we get a pre-radiation MRI to determine most accurate area? Depends on physician, usually will get an MRI or CT scan.
* Should there be any MRIs done in between to check if it is working? Don't do it during, 6-8 weks after
* What is currently being done to improve the efficacy of this treatment (experimentally, clinically, etc?) www.nci.gov click on pdq type in type of tumor, region, trials it will pop up list of trials
* Are there any other treatments that we can do with this treatment or before/during/after that we should consider? Anything in setting of clinical trial
* What does this treatment prevent you from doing in the future? Does it preclude other types of radiation (ie external treatments like gamma knife & proton or gliasite or other internal radiation therapies) Again depends on dosage of radiation given to tissue.
* If a tumor shows up in a different part of the brain or body, would this treatment or even standard radiation be applicable on the new tissues? yes
Radiosensitizers -chemicals that modify a cell's response to radiation - not usually used for proton therapy
Radioprotectors - drugs that protect normal cells (promote repair) from damage caused by radiation therapy - not routinely used but sometimes in trials