Kate,
In response to a couple of your questions
What type of surgery did you have?Researched both extensively like most folks , opted for CK. I thought that was noted on my profile whenever I post, I'll have to check
My statistics come from various readings including House Ear. I found in my reading, that when the tumor was under 2 cm, facial preservation was consistent between surgery and radiation.
"Results of surgical procedures for treatment of acoustic neuroma at the House Ear Clinic with respect to facial nerve preservation are greater than ninety-eight percent (98%)."I know from reading many of your posts that you do reference HEI as a source many times. While in no way diminishing their surgical expertise and acknowledging that they will tend to have better outcomes than most others, I personally do not feel comfortable with much of their information as credible for the following reasons:
1) While not a subscriber to medical journals, I can't remember the last time I found a clinical study by HEI in one when I did a google search. That process requires peer review and challenge before publication which at least validates the study methodolgy by outsiders. Anything else is self reporting which either may be legitimate or propaganda.
2) their web site comments relative to radiosurgery historically have been inaccurate when compared to the vast majority of published studies. In my view, they either haven't taken the time to stay current on that topic or are reflecting a bias and that tend to taint my view of their claims in other areas. just my opinion there
We can agree to disagree on HEI's credibility for a balanced view of both treatment options, but I look at information self reported by them as questionable.
In my reading, I found hearing preservation wasn't the main reason person's chose radiosurgery. The UPMC article is from their website and one that they keep posted on their site to this day. Actually even though 1998 sounds outdated, that is approximately the time Cyberknife began. Cyberknife has a recent (and it appears in this decade--a successful) history.Clearly, there are many valid and very personal reasons each individual chooses an option. On the emotional side there is "I just want it out", fear of surgery, fear of radiation etc. On the outcome probability side there is the analyzing and interpreting of all the various studies one can find. Sorting through the various issues relating date, methodology and bias is a challenge for everyone. Given that facial nerve preservation is a higher priority than hearing and that hearing is to some degree compromised to some extent for all of us before treatment, I would agree that hearing is not the main reason for choosing either option.
In the context of your post, the issue you raised was the differential in result probabilities as the size of the AN increased which generally favors radiosurgery which I agree with. My counterpoint was only to the point of where the "delta" between the 2 options begins. You suggested it is the roughly the same until after 2 cm , I would suggest it's closer to 1 cm for both hearing and facial function. the caveat I would stipulate to on the facial side is if you distinguish between surgical approaches. A study I just found this morning does indicate that the translab approach can have a high 90 plus % result up to 2 cm, but not the middle fossa. If the 98% you quoted from HEI is specific to TL then another study would seem to validate that. However, the way your post read there was no indication that they were not making an assertion regardless of route.
OK, here are a couple of studies I would offer to the discussion
While I wish more studies would isolate data by AN size, only a few seem to do that. Here is one from UCSF dated 2001 which I based most of my comments on
http://www.ucsf.edu/nreview/06.4-Oncology-HistologicalType/AcousticNeuroma.htmlThe relevant table is this
Cranial Nerve Preservation Following Surgery
Tumor Size VIIth Nerve VIIIth Nerve
< 1 cm 95-100% 57%
1-2 cm 80-90% 33%
>2 cm 50-75% 6%
A 2002 study by Robert Jackler , et all comparing middle fossa to translab. Dr. Jackler is probably one of the most published clinicians on AN's in the world. I still have the 2 inch thick stack of his articles he gave me at my consult
. This supports the claim of comparable results at 1 cm or below to what is observed for most radiosurgery studies, but also shows declining outcomes for middle fossa between 1-2 cm, but equivalent facial for translab to that size. Of course hearing is a non issue forTL at any size.
http://med.stanford.edu/profiles/frdActionServlet?choiceId=showPublication&pubid=40759&fid=3947the abstract is
Risk-benefit analysis of using the middle fossa approach for acoustic neuromas with >10 mm cerebellopontine angle component.
Satar B, Jackler RK, Oghalai J, Pitts LH, Yates PD
OBJECTIVES: To evaluate hearing preservation and facial nerve (FN) outcome in the middle fossa (MF) approach for acoustic neuromas with a cerebellopontine angle (CPA) component >10 mm. STUDY DESIGN: Retrospective review of 193 patients. PATIENT POPULATION: Patients were grouped according to tumor size: intracanalicular tumors (IC; 64), 1 to 9 mm CPA extension (42), and 10 to 18 mm CPA extension (47). Additionally, a group of 40 patients (tumor size 10-18 mm CPA extension) who had undergone a translabyrinthine (TL) approach was studied to assess comparative FN outcome. Hearing and FN function were measured 1 year postoperatively. We defined the success at functional hearing preservation as AAO-HNS class B or better and good FN outcome as House-Brackmann grade II or better. RESULTS: For IC tumors and those with up to 9-mm CPA extension, there was no significant difference in the rate of functional hearing preservation (62.2% vs. 63.1%, P =.931) and good FN outcome (93.7% vs. 97.6%, P =.358). For tumors of 10- to 18-mm CPA extension, the rate of hearing preservation (34%) was lower than the other groups (P =.006 and P =.009). In this group, the rate of good FN outcome was lower compared with the IC and 1- to 9-mm tumors (80.8% vs. 93.7%, P =.037 and 97.6%, P =.012). The rate of good FN outcome following the TL approach in a comparable cohort of patients was 100% (P =.003 in comparison with 10-18 mm tumor resected with the MF approach). CONCLUSIONS: When considering surgical options, patients with >10-mm tumors should be advised that choosing the MF approach for hearing preservation carries a somewhat higher risk of persistent FN dysfunction.
Study by Steve Chang et al on CK results as of 2005. I understand there is an updated report due out in a couple of months with a larger study sample size and obviously follow up period
http://med.stanford.edu/profiles/frdActionServlet?choiceId=showPublication&pubid=66900&fid=4735the abstract is as follows and suggests better hearing and facial nerve outcomes than the 1998 study and includes all AN sizes
Neurosurgery 2005; 56 (6): 1254-61; discussion 1261-3
Staged stereotactic irradiation for acoustic neuroma.
Chang SD, Gibbs IC, Sakamoto GT, Lee E, Oyelese A, Adler JR
OBJECTIVE: Stereotactic radiosurgery has proven effective in the treatment of acoustic neuromas. Prior reports using single-stage radiosurgery consistently have shown excellent tumor control, but only up to a 50 to 73% likelihood of maintaining hearing at pretreatment levels. Staged, frame-based radiosurgery using 12-hour interfraction intervals previously has been shown by our group to achieve excellent tumor control while increasing the rate of hearing preservation at 2 years to 77%. The arrival of CyberKnife (Accuray, Inc., Sunnyvale, CA) image-guided radiosurgery now makes it more practical to treat acoustic neuroma with a staged approach. We hypothesize that such factors may further minimize injury of adjacent cranial nerves. In this retrospective study, we report our experience with staged radiosurgery for managing acoustic neuromas. METHODS: Since 1999, the CyberKnife has been used to treat more than 270 patients with acoustic neuroma at Stanford University. Sixty-one of these patients have now been followed up for a minimum of 36 months and form the basis for the present clinical investigation. Among the treated patients, the mean transverse tumor diameter was 18.5 mm, whereas the total marginal dose was either 18 or 21 Gy using three 6- or 7-Gy fractions. Audiograms and magnetic resonance imaging were obtained at 6-months intervals after treatment for the first 2 years and then annually thereafter. RESULTS: Of the 61 patients with a minimum of 36 months of follow-up (mean, 48 mo), 74% of patients with serviceable hearing (Gardner-Robinson Class 1-2) maintained serviceable hearing at the last follow-up, and no patient with at least some hearing before treatment lost all hearing on the treated side. Only one treated tumor (2%) progressed after radiosurgery; 29 (48%) of 61 decreased in size and 31 (50%) of the 61 tumors were stable. In no patients did new trigeminal dysfunction develop, nor did any patient experience permanent injury to their facial nerve; two patients experienced transient facial twitching that resolved in 3 to 5 months. CONCLUSION: Although still preliminary, these results indicate that improved tumor dose homogeneity and a staged treatment regimen may improve hearing preservation in acoustic neuroma patients undergoing stereotactic radiosurgery.These would be what I would base my previous thoughts on
Best,
Mark
