The short answer to your question is 'sometimes'. For what its worth, here's my story:
I was diagnosed with a 4.5 cm AN in 2006. It was pressing 'hard' on my brain stem although my only symptoms were dizziness, fatigue and loss of taste. My hearing in the affected ear had been lost some time previously (the price of procrastination on my part). My neurosurgeon, reacting to my clearly stated desire to avoid facial nerve complications, offered a plan (I accepted) to perform a partial resection (Retrosigmoid approach) of the tumor, in effect to 'thin it out' and then radiate it via FSR to spare adjacent nerves and brain tissue. He didn't believe it was a good idea to wait until possible re-growth to begin radiation. He wanted to dispense with it as soon as possible. During the surgery, the doctor severed the tumor's blood supply, further weakening it. I liked that.
Long story short:the surgery was successful. My symptoms immediately disappeared (bi-ilateral hearing never returned). I recovered quickly and underwent a five week regimen of FSR 'treatments', totaling 27 Gy. No complications whatsoever with the FSR. Subsequent MRI scans at six months, a year and two years post-surgery/radiation indicated tumor necrosis and the beginnings of shrinkage. At the seven year mark, I'm doing great (no AN symptoms).
I'll likely have a follow-up MRI this year but have no symptoms so I'm not concerned with re-growth at this point, although I'm aware it is possible, if not probable. However, I have to add the usual caveat that we're individuals, many factors are in play and one person's AN surgery/radiation outcome is not a template for anyone else. It's just my experience and I wanted to share it as a form of, what I hope, is encouragement as you face a decision on your AN treatment.
Jim