You are right. One study I read states that long-term (7 years post-radiation) hearing preservation was ~32%. This is my biggest concern. Conversely, I also read a study (I believe in the Journal of Neurosurgery, Dr. Kondziolka was one of the authors) which states that if patients have a small AN,
are <60 years old, with high level of hearing retention and high word recognition, then hearing retention after 5 years was actually quite high (~70% I believe).
This touches on a key topic -- there seems to be literature supporting a variety of treatment modalities. Some literature states that wait and watch is appropriate b/c these tumors are slow growing and a critical number of patients experiences no tumor growth 4 years after diagnosis (I believe ~40% of patients is the number). Conversely, there is some literature that states early intervention results in better outcomes and increased likelihood of hearing retention (i.e. wait and watch sacrifices hearing).
Then, some literature states microsurgery is better for patients that do not have any existing conditions which would make them not a candidate for surgery. Conversely, other information leads one to believe radiation is better for certain individuals with tumors of a certain size.
And then, there is a Mayo Clinic study that states patient quality of life is approx. the same regardless of treatment modality (microsurgery vs. radiation).
I've read a lot (like many here), probably too much. Honestly, I've reached the point of diminishing returns (if anything, I'm getting negative returns for my time spent reading on this topic.). This is what I've learned - I am not an expert. I've been thrust into this world ~1 month ago. All my reading is a drop in a bucket to the data which very experienced surgeons have on this topic. I also know surgeons have biases -- whether it is their training, their willingness (or lack of) to change approach based on new info., or financial incentives.
Surgeon engagement is another topic. Some are wonderful -- they spend quality time with you (30 mins or more), share detailed information about your specific situation, are compassionate, etc. Others are not so wonderful -- spend 15 mins with you, stare mainly at their computer screen as they document the conversation, and maybe give you 4 mins of eye contact.
ANs are an interesting heath care topic. They are not life threatening, however, they can have a significant impact on quality of life. The incidence is low so we may not see a robust, convincing study in the foreseeable future recommending approach X versus Y.
So...what to do...I guess evolve the conversation with the surgeons to address 'my' specific situation. Size of tumor, location (vs. cochlea), age, work/life, etc... And then, make a call about the treatment modality (or lack there of) and surgeon. Feel good about that call. To some extent, this seems to be a probabilities game.