Hi, Beth:
I had CK 1 year ago and considered it to be very successful. More on that in a bit, but first here's what I would say about the comparisons between CK and GK:
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. 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.)
Like a number of other people who have posted on this thread, I also had CK performed by Dr. Chang. I have the highest regard for him. If I had to choose GK, I would've chosen Univ of Pittsburgh. I agree with Marianna that they are the gold standard for GK treatment.
Here's my experience with CK (your mileage will vary): Much of my experience was unusually difficult and also unusually beneficial compared to what others have experienced after CK. My first 2 months after treatment were very difficult. I suffered profound fatigue, accompanied by shortness of breath, and my disequilibrium became (subjectively) about 15 to 20% worse. I also had about a week of hyperacusis, accompanied by slight hearing loss, about 4-1/2 months after treatment. Overall, I lost about 20 dB of hearing in my midrange frequencies over the course of a year post-treatment.
That's the bad news. The good news is equally unusual. Immediately after CK, the pulsatile component of my tinnitus disappeared completely, never to return since. The ringing tinnitus I'd suffered for the previous 8 years or so was also quite dramatically lower in volume. My first followup MRI (taken 5 months post-treatment) showed unusually widespread necrosis (tissue death) spreading nearly throughout the entire tumor. Unfortunately, my tumor had also swelled 36% in volume. But at the 6-month mark post-CK, I began to feel rapidly better. My balance improved significantly, and I now have decidedly better balance than I did before receiving CK. In fact, my balance is better now than it's been in the past 9 years.
When it came time for my 1-year followup MRI a couple weeks ago, I was nervous that the tumor may have swelled more. To my (and everyone else's) surprise, the tumor had shrunk -59% in the past six months! To those lucky enough to have their tumor shrink, that degree of shrinkage usually takes five years (according to Dr. Chang).
My results from CK are unusual in many ways, so you shouldn't expect to have the same benefits (or the difficult side effects immediately after treatment) to the degree I have had them. But you asked to hear positive stories about CK, and I certainly regard my outcome to be very positive. I am 100% happy with my decision to have CK with Dr. Chang at Stanford. It's one of the best decisions I've ever made in my life. The road to recovery was rough for me for the first six months after treatment, but the ride was worth it because of the eventually very positive outcome.
May your journey be smooth and peaceful and your healing swift and thorough.
Best wishes,
TW
