If the tumor is too large or the position is not good are the main reasons for NOT being able to do GK if I understand correctly. Someone else can certainly give you better answer...Steve, where are you?
Late, apparently.
![Embarrassed :-[](https://www.anausa.org/smf/Smileys/classic/embarrassed.gif)
But I think you got it right. The principle concerns are pressure on the brain stem from swelling, and radiation exposure of the brain stem, which is sensitive to it.
I would add that in some cases, where the balance nerve is causing severe vertigo, surgery may be preferred so that the balance nerve can be cut. For large tumors over 3 cm, the radiation dose needed would be too large to risk it, in most cases. And, since radiation takes a while to have its effect, there is some concern if you are planning a pregnancy in the next year, since it seems to have a tendency to jump start AN growth.
The other concerns mentioned in various posts, once you look at the numbers and do the math, are not really very significant. For instance, second treatments are harder than first treatments - regardless of which treatment choices are involved. The extra risk of facial nerve damage, if you have regrowth (2% chance), times the risk from the difficulty of second surgery (25%), works out to an added 0.5% risk. Not really worth worrying about.
I will just add that you should consult with a radiation oncologist, rather than a surgeon, if you want to get a well informed view of whether radiation is suitable in your case. Go to the pros in each field for their advice on what they know best.
Best wishes,
Steve