AN regrowth after retrosigmoid, then Gamma Knife

[MarkS]

Hi all,
I first posted here 2 years ago when I had my AN surgery.  Wanted to give an update, and I have a couple questions if anyone else is in my (shrinking) boat.
I had my initial surgery (retrosig) at MD Anderson.  Dr. Demonte got the vast majority of it out, but could not get it all due to adherence to the facial nerve.  The hope of course was that the remainder would not regrow, but it did.  4mm of growth was observed in the past year, which they say is faster than average.
However it was still much smaller than before, so this time radiation was an option.  So, this Monday (Mar 4th) I had Gamma Knife, also at MD Anderson.  40-minute exposure to Cobalt-60.  It went fine, as far as I know.  Only side effects were a few days of fatigue and moderate headaches.  Of course, it remains to be seen if the treatment actually worked, i.e., killed the tumor.  So here are my questions; maybe y'all can shed some light.
1) What are the odds that the GK will kill it or at least stop it from growing, such that no further surgery or radiation is required?  My oncologist Dr. Chung said 85%.  Does that jibe with any stats y'all have heard?
2) How long SHOULD it take until an MRI will show signs of tumor death?  I have an MRI scheduled for June 3rd.  Is that too soon to know?
3) If it doesn't work long-term, and regrowth is observed in the future, is it possible to get GK repeated as necessary?  (Perhaps the feasibility of that depends on the time between treatments.)  Or at some point is GK taken off the table and a second surgery become necessary?  I want to avoid that at all costs because I suspect facial paralysis would be likely this time around.
Mark

[ColleenS]

Hi there! Odds you say, we are all different. It depends on so many things.

1. I was given a 90% chance of radiation killing my tumor. My 3-month recheck showed it was killing the tumor - yay!
2. I had Translab surgery and 15 months later my tumor regrew to almost the original size from the fragment left on the facial nerve. How long does it take to show tumor death? I read anywhere between months and 2 years - I was one of the lucky ones to show quickly. I had a different type of radiation than you though - so everyone is different.
3. My understanding (I am not a doc) you can only get radiation in the same place - once.

[MarkS]

Thanks for the helpful info Colleen!
What kind of radiation did you get, and why?  I wonder what the factors are that go into determining it...
Mark

[gary.s]

Hi MarkS,

I had Cyber Knife about ten months ago in Arizona. My last MRI was in November of 2018 which was about seven months post CK. My tumor showed some signs of shrinkage and necrosis within the tumor. So for me, seven months was long enough to show some changes due to radiation. Since we all respond to treatments in different ways, it is hard to tell what your tumor will look like in June.

Three months may be too soon to indicate a change to the tumor, but that is something to discuss with your doctor. Dr. Chung may have other reasons to have an MRI done than seeing if the tumor is dying at this point in time. I had an MRI done at one month after CK because my doctor wanted to get some baseline data on the tumor. It showed no change after one month. I hope this information is helpful. Best of luck and hang in there.

Gary

[ColleenS]

I had five doses of radiation 26 min each using Linear radiation (https://www.radiologyinfo.org/en/info.cfm?pg=linac).
I am not sure how they choose the type. Could be size, placement, growth rate etc..