Hi Kathy,
My AN had a big cyst inside it. My first MRI was in May last year and at that stage the AN was 2.4cm. Long story but I didn't get my MRI results until Sept that year... I then had another MRI in December, the AN by then had grown to 2.7cm. As you say 3mm is not much growth in the grand scheme of things. From what I've read they usually only grow about 1-2mm a year. So 3 mm in less than a year is more than usual and I was told it was due to the cyst growth as opposed to the actual tumour growing. However as the cyst is inside the tumour it has the overall effect of causing the tumour to be bigger... if you get me. Although it's not much when you're looking at an AN that's over 2cm it's probably (in the case of mine anyway) starting to move towards the brain stem and push into it which is when you want to do something about it. I'm not sure where your other mass is so I'm not sure what your options are there.. but I would say given the size of yours you probably still have both gamma and operation as options. Mine, because of where it was (pushing into the brainstem) and because of the cyst inside it and because of the size, it was judged too risky for radiation - they said the cyst would stop the radiation getting to the other side of the tumour etc etc.... so I had surgery 4 weeks ago today and it was a success. I'm really happy, tumour is gone, facial nerve intact, feeling great. I think people on the forum who have had radiation will be able to give you more advice on that than I. All I know is that for me it wasn't an option, but it may well be for you.
It's scary stuff when you first get diagnosed, I know how you must be feeling. Take a deep breath. Know that your AN is absolutely treatable and it sounds like your other mass is too. You have time to make a decision, you're doing the best thing in researching your options. You can make the best decision for you when you have information about the different options. Once you make your decision I hope you will be a lot calmer and feel good about the decision, that's how I felt.
Good luck, I'm sending you some relaxation vibes, I hope they work. Take strength from all the lovely people on the site - they helped me a lot!
xx
JB