Hi, Stephen. Welcome to the ANA discussion forums.
I'm sorry to learn about your apparent AN re-growth but this can occur, as you well know. As my fellow moderator, Phyl stated, I underwent tumor debulking followed by radiation (FSR) in a planned 2-step process. Here's my story:
I was diagnosed (via MRI scan with contrast) with a 4.5 cm AN in May, 2006 after experiencing all the usual symptoms including a complete loss of hearing in my left ear. My hearing in that ear had slowly disappeared over an approximately 5-year period (and I foolishly ignored it). I was very concerned about facial paralysis and made this abundantly clear to my doctor, a neurosurgeon who had been removing acoustic neuromas for 30 years. He shared my concerns and proposed a two stage approach to my AN. First, the 'debulking' surgery (using the retrosigmoid approach), followed by a 90 day 'rest period', then 26 FSR treatments, 'mapped' by the neurosurgeon and a radiation oncologist he worked with on his AN cases. The idea was to basically 'gut' the tumor down to a thin membrane that would be highly susceptible to the effects of radiation. I had complete confidence in this doctor and so, I approved the plan and surgery was scheduled. Long story short: the AN debulking surgery went exceedingly well and I suffered no real complications. I recovered rapidly and was ready for the radiation treatment, three months later. The radiation oncologist informed me that he had kept the radiation 'dose' as low as possible (a total of 27Gy) to spare me any negative reactions. I'm happy to report that I had none, unless you count boredom. My last MRI showed definite necrosis (tumor cell death) and the beginnings of tumor shrinkage. My symptoms disappeared immediately following the surgery and, with some work on my balance, I'm in excellent shape, overall, considering my age (68). As Phyl stated, each AN patient is different and outcomes, good or not-so-good, can never be guaranteed. However, radiation treatment following surgery is usually very efficacious. It certainly was for me.
As for ANs turning cancerous from radiation, your research will show that the chances of that happening are infinitesimal. Probably about the same as winning Powerball. It has to be mentioned but I wouldn't let that distinctly remote possibility worry you too much. I trust this information will be useful to you and help you make a decision on radiation treatment.
Jim