Hi, Debi ~
My fellow moderator, Steve, usually answers these questions succinctly but since I got here first, I'll offer you my opinion.
I believe it's as much perception as reality that 'the majority of doctors prefer surgery over radiation' because a new AN patient is very often referred to a neurosurgeon, who will, quite logically, believe that surgery is the best solution to an acoustic neuroma because that is what he does, and if he isn't current with AN-related procedures, he may well think that he is offering you the best option. This is why you need to have at least two doctor consultations and one with a radiation oncologist, if possible.
The rationale for doctors advising against radiation treatment for acoustic neuroma used to be exactly what you stated, i.e. that the radiation will cause you to 'max out' your body's safe radiation level (because the radiation stays in your body) making future radiation treatments (for cancer, usually) impossible. Not exactly. The radiation you receive to treat an acoustic neuroma is extremely localized to the precise area where the AN resides and doesn't preclude radiation treatments (in other parts of your body) in the future. Others may be able to elaborate on that issue.
The old canard about the radiation-treated area (which is quite small) being harder to work on if surgery is required (assuming radiation fails to kill the tumor) has been pretty much disproved by reality. Unfortunately, some surgeons tend to cling to this supposition, even when it has been proven more theoretical than real.
The risk of surrounding cells becoming cancerous is infinitesimal, at best and not a real concern.
I underwent 26 FSR treatments and wasn't concerned about any of these alleged 'risks'. My neurosurgeon performed debulking surgery (cut my large AN down to a more manageable size) and worked closely with a radiation oncologist to 'map' my radiation treatments. Both surgery and radiation were successful with almost no noticeable complications. I was never 'warned' of any real risks with the radiation, except that the radiation oncologist explained the procedure and basically laughed at the 'old wives tales' about the alleged 'dangers' of radiation on acoustic neuromas. He admitted the infinitesimal 'risks' but said he had never seen any of these occur. I believed him. So far, so good.
I trust these answers will prove useful to you.Jim