I agree with Steve, but will add that, IMO, the chance of hearing preservation is greatest with treating large tumors with radiosurgery, too. That's because a large tumor virtually always requires either a translabyrinthine or retrosigmoid surgical approach. Translab destroys all hearing structures on the affected side, leaving the patient deaf. Retrosigmoid surgery for a large tumor almost always results in complete loss of hearing (although there are exceptions).
Here is an excerpt of a post I wrote a few months ago, before receiving CK. It goes into more detail comparing surgery with radiosurgery (both GK and CK):
With surgerical resection (cutting the tumor out), you run a much higher risk of damage to facial nerve function compared with radiosurgery's results in that regard. For example, with my size tumor, I stand about a 31% chance of permanent ipsilateral facial paralysis with surgery, but only 1% chance of same with GammaKnife or CyberKnife treatment. Resection also poses other risks: roughly 10-15% chance of chronic headaches (thought to be due to bone dust being left behind inside the cranium after the operation), a slight chance of cerebrospinal fluid (CSF) leakage, and (very rarely) cognitive or behavioral changes (memory loss and personality changes). And in many cases, surgery involves cutting the vestibular (balance) nerve, whereas radiation treatment preserves the anatomical continuity (but not always full function) of the vestibular nerve. So I personally think you're on the right track with choosing some type of radiosurgery (one-time radiation treatment) or radiotherapy (fractionated radiation treatment, or that which is split up into multiple smaller doses). That said, radiosurgery/radiotherapy only (hopefully) kills the tumor and does not remove it (like resection would). The recurrence rate for surgery and radiation are about the same (cited to be roughly 2 to 3% in most studies).
As for radiosurgery, GammaKnife (GK) and CyberKnife (CK) are both more accurate than standard FSR (fractionated stereotactic radiation) such as Novalis. CK is also a form of fractionated radiotherapy, but its accuracy gives it a leg up on standard FSR.
CK delivers a more homogeneous dose to the tumor compared with GK. CK delivers only 15% higher dose to the center of the tumor than at the periphery, whereas GK delivers fully double (100% greater) dose at the center compared to at the periphery. CK advocates believe that GK's higher dose at the center of the tumor increases the chance of damage to nearby healthy tissue August 8,2008 P.S.: and especially to the vestibular nerve, which runs down the center of the internal auditory canal and therefore receives a full hit of radiation if the tumor fills the entire IAC. Also, GK delivers one large dose to the tumor because one treatment is all you can do with GK (this is because a ring is fitted to your head for the treatment and, once it's removed, there's no way to get it exactly in the same place for a second treatment). With CK, on the other hand, a thermoplastic mask is custom-fitted to your head and the tumor's location (in relation to the mask and your bony structures) is plotted into the computer; on followup visits for treatment, they put the mask on your head again and you're ready for the next dose. This flexibility allows CK to apply smaller doses to the tumor than GK with each treatment; together, the smaller doses add up to the same total biologically equivalent dose as you would get with GK's one and only treatment, but (theoretically, at least) the hearing nerve and other healthy tissue has time to recover in between treatments (whereas the tumor supposedly doesn't recover as quickly). Presumably due to the fractionating of dosage, studies show CK yields slightly better results at preserving hearing compared with results for GK. Furthermore, GK's ring is screwed into the head (the screws stop at the skull) to keep it stationary (so that the radiation stays focused on the tumor), a mildly invasive procedure. CK is totally non-invasive: a series of overhead X-rays tracks the patient's head movements and tells the computer-controlled CyberKnife machine which way to move to track any small movements the patient may make so that the radiation stays centered on the tumor. GK advocates say that's all well and good, but GK has about 40 years of track record, whereas CK has been around a lot less time and is not as proven of a treatment as GK. (CK was approved by the FDA in 1999, although Stanford University Medical Center has been using it since 1994 in clinical trials because their Dr. Adler invented CK.)
Best,
Tumbleweed
