Thanks to all for their comments and assistance - especially Mark whose magic seemed to help things along.
I was provided with Dr Chang's e-mail and the e-mail of a nurse pratitioner in the clinic at Stanford. I sent off my questions to Dr Chang yesterday afternoon. By the time I logged on this morning (9am DC time) he had replied to all my questions. In the interest of wiping Stanford's slate clean here is the nurse practitioner's reply:
"we have 3 nurse practitioners who work in the Cyberknife team. We do a weekly pro bono review of outside scans a week. We literally review dozens of scans each week to help people with decisions on treatment. Usually we try and call the patient to discuss the review. It is rare that we just send an e-mail. I will give Dr. Chang an opportunity to answer your ?s. If you wish to talk to me – you can call me or the other 2 nurses anytime."
I also thought that some may be intersted in Dr Chang's replies to my questions. They're questions I think most people would ask in a consultation and his answers are considered and in plain english (always a good thing - shows he knows his stuff). So here are my questions and his answers:
1. On the basis of the position of my AN in the CPA and its protrusion from the IAC what do you judge to be the relative risks of CK and surgery (which I understand would have to be done through the sub-occipital approach)?
The surgical risks of the surgery include the usual infection, bleeding, stroke, anesthesia, etc. The specific risks to the hearing nerve for a tumor your size is at least 90% chance of hearing loss even with a suboccipital approach. The risk of facial nerve injury would be on the order of 20-25% with surgery. The risks of facial nerve injury with cyberknife is less than 1%, but again, that is an average, so it is possible to have facial injury with radiosurgery. The probability of maintaining your hearing is at least 70% with radiosurgery, but that means 30% may have some decrease, with the average decrease being 12 dB and an occasional rare patient having complete hearing loss
2. As you may be aware I am a musician and a key goal in treating this is retaining my hearing given that it’s highly serviceable in the speech range (and <20dB difference between left and right ears). I am attracted to the CK approach. Can you tell me precisely what your outcomes are for hearing preservation and tumor control for a 1.77cm AN?
2. As far as hearing preservation, the risk with the cyberknife is not related to tumor size to any significant extent (unlike surgery) so I cannot make a generalization as to how 1.7 cm ANs do. The average hearing preservation rate is 74 to 77%. The average dB decrease in all patients (those 70% that maintain hearing and the 30% with decreased hearing is 12 dB). Incidentally, hearing loss at the time of presentation is also not necessarily correlated to size of tumor. I have many patient with a AN over 20 mm that have normal hearing, and other with decreased hearing at 5 mm
3. If I was to have CK what treatment regimen would I undertake? How many fractions, what dosage (including how much total dosage) and why?
3. We use 18 Gy in 3 treatments of 6 Gy each. We feel that is the best balance between dose to kill the tumor and minimizing risk to the hearing nerve. We have used 3 treatments for 12 years now, and our current dose of 18Gy has been used since 1999.
4. Would you be so kind as to explain the process – how the Accuray machine determines the position of each “shot�? Would you also advise who does the programming? Do you supervise the procedure or do you delegate it? If so, to whom do you delegate?
4. The choice of the positioning for each beam is chosen by the computer. The doctors input the tumor volume, and the computer calculates the optimal beam positions based upon the millions of possible iterations. The beam positions are not chosen by a human, but by the computer, so there is not any human input as to the choice of beam positions, and therefore nothing that gets delegated since it is all done by the computer.
5. What is your measured error distance for the “beam�?
5. Total clinical error is between 0.9 mm and 1.1 mm for the treatment. The largest sources of error 0.6 mm actually comes from the errors intrinsic to the CT and MRI images.
6. How long have you been using this particular protocol? When did you last change your protocol?
6. We have been using our current protocol since 1999, with no changes.
7. Given no complications, at what frequency would I need to have follow-up MRIs?
7. We typically request MRI and audiograms every 6 months for the first two years, and then once a year for the next two, and then every 2 to 3 years after that
8. Every surgeon to whom I have spoken has recommended surgery, and every radiosurgeon radiosurgery. Would you give me a medical reason why in my case CK is preferable over surgery? Is the tumor sitting side by side with the cerebellum? If so, and swelling occurs post CK treatments, what damage (and symptoms), both permanent and temporary can I expect? I am currently reasonably asymptomatic for an AN of this size.
8. I can't speak for other surgeons, but I do both open surgery and radiosurgery, with roughly a 50-50 balance between the two. Last year I treated 600 patients, with brain tumors, with slightly less than 300 going to the operating room and slightly more than 300 receiving the Cyberknife. I operate on large acoustic neuromas, and I do radiosurgery on most others. Since I do both, I try to choose the best treatment option for each patient.  I presume that the other physicians that you mention may only do surgery, for example, but I know of very few people that do radiosugery than do not do open surgery. I suspect that those that you have spoken to also do open surgery, but I also suspect that those that you have spoken to regarding surgery only do surgery.
Radiosurgery is not zero risk, but the risks are much lower than open surgery. I base my recommendations in your case on what I would do if I had this tumor or if it were in my mother or father, and if it were me or them, I would choose radiosurgery. Each patient needs to make their own decision however, so you would need to choose what you feel comfortable with.
I'm pretty happy with the comprehensive replies to my questions. And, although I offered payment for a phone consultation he refused as apparently insurance companies define "consultation" as a physical examination of patient by doctor and this obviously can't be done over the phone. So there you are. Seems this whole episode may have been a glitch in the system but good to make them aware when things go awry. I would probably have just gone eslewhere had it not been for Mark's intervention. Lesson to the wise I guess. I just wait to get House's diagnosis today - primarily to compare information - I really don't want anyone going into my head at this stage now. Maybe in 10 or 20 years but not now.
CC
