fractionated versus single dose delivery of radiation

[Pim]

Dear all,
 
My name is Pim and I live in The Netherlands. I just learnt of your great Forum and hope you can be of help to me.
 
Recently I was diagnosed with an Acoustic Neuroma.
I am 59 years old, meaning there will be lots of time for the effects of radiation to emerge later in life. I have a  mild decreased hearing at left side, marginal tinnitus and balance problems. Facial function is normal, no brainstem compression.
The length of the tumor of 17 mm, cross diameter outside the canal is 8 mm
 
Could you please comment on my research so far:

Fundamental decision
Surgical resection has a high risk of hearing loss, a meaningful risk of facial nerve damage and other risks, associated with surgery such as infection, swelling, anesthesia. There are quality of life risks as well: ongoing post treatment symptoms such as intense headache.
In view of these issues, radiation surgery seems to be the better choice for me.

Gamma knife vs. CyberKnife
On the radiation surgery, two competing technologies are available for me: Gamma knife and CyberKnife. Both have comparable tumor control rates and the risk of facial nerve damage is in both cases negligibly small. There is one key difference between the two (apart from the headframe drilled into the patient’s skull in case of Gamma knife): Gamma knife delivers radiation in a single dose while CyberKnife delivers radiation in 3-5 fractions.
Question 1: is there any difference in the medical efficacy of single dose vs. fractionated delivery of radiation? 

Hearing preservation rates seem to be much better in case of CyberKnife. This is important for me as I still have ‘useful hearing’ (G-R scale I). According to most radiation surgeons, that I talked to, this is due to the more friendly fractionated delivery of radiation to the nerves and surrounding tissue.
Question2: is there any relationship between single dose or fractionated delivery and the hearing preservation rate?
Question 3: do you need exact planning of inside canal dose of radiation necessary to reduce the cochlear radiation dose if hearing is to be preserved? 

[sgerrard]

Hi Pim,

First let me say welcome to the forum, and that you seem to have done your homework well. I think you already have a very good sense of how things stand.

To answer your specific questions, I would say

1. No, both GK and CK have shown similar high control rates. The older FSR procedure with 25 fractions is maybe a little lower. At Stanford, where I had CK, the control rate has hovered around 99% for almost 10 years now.

2. Hearing preservation with CK is generally considered to be somewhat better than GK, perhaps 75% versus 65%. This is usually attributed to the gentler approach of 3-5 treatments. Hearing preservation seems to work best when you have a relatively high level of hearing going in.

3. The treatment planning is automated, and the doctors have the opportunity to identify critical structures that should not receive high radiation dose. They do identify the hearing organs and nerve when developing the plan, though protecting the brainstem has higher priority.

People who do surgery in your circumstances often come through it quite well, with acceptable post surgical effects. But as a radiation patient myself, I tend to agree with you that radiation seems like a good choice for you. I would not be concerned about effects emerging later in life, they are very rare in this kind of radiation treatment.

Best wishes,

Steve

[Jim Scott]

Pim ~ Hello - and welcome!

As Steve noted, you appear to have done extensive research and have a good idea of what you want to do. Steve, an AN patient who underwent radiation treatment (successfully) has  answered your questions and although others may choose to elaborate, I'll simply offer you my support and encouragement as you move toward a final treatment decision.

Jim

[CHD63]

Pim .....

Just want to add my Welcome to our exclusive little group!     You will find many kind, caring, supportive people here.

It sounds like you are well into the "research-phase" of this journey and have done your homework.  I would like to add that each of us have unique brains so the outcomes given for any procedure are only statistical in nature ..... not absolutes of what you will have happen.  Many on this forum have retained their hearing after surgical resection.  Many of us have had no headaches following surgery either.  Tinnitus and balance problems (usually resolving to a manageable level after any treatment) are pretty universal with ANs.

Our thoughts as you complete the decision-making phase of this process.  Keep posting to let us know how you are doing.

Clarice

[ppearl214]

Hi Pim and welcome! Good to have you here and glad you found us.

Well, it does certainly sound like you have done your research and I can't add too much more to what Steve has already shared with you. 

From a personal experience standpoint, I can share that I opted for fractionated CK (mine was done over 5 days) over 3 years ago, with the hopes of hearing retention (my hearing, at the time, was over 90% and as of today... it remains over 90%).  I had learned that by fractionating the doses... it would help the surrounding structures (ie: brainstem, etc) take a lower hit of radiation thus, trying to help ensure lower doses with slight time breaks in between (ie: each day)... there was a higher amt of hearing preservation. In my case... I am one of those success stories

Again, welcome and best wishes with your decision.

Phyl

[Pim]

Dear all,
Thank you for all these nice and motivating reactions. I highly appreciate to be accepted into your group as a far-away Dutchman.
If I understand your advices and experiences well: I should go for fractionated CyberKnife treatment. As I still have useful hearing (G-R scale I) this will optimize the chance for hearing preservation.
However, Neurosurgeons in Europe emphasize that single dose is the better choice for small tumors as it is less toxic and delivers less radiation to normal tissue.
So, what should I do? Give preference to less radiation (single dose) or to the chance of optimal hearing preservation (fractionated)?

[fbarbera]

Hi Pim,

I would post your last question to the doctors on the Cyberknife Forum - these are volunteers physicians with a lot of knowledge and experience - they respond to patient questions rapidly and will be able to address your concerns. 

http://www.cyberknife.com/Forum.aspx

I too was deciding between GK and CK and for the reasons detailed in my website below, decided to go with CK.

Best wishes,

Francesco

[suboo73]

Hi Pim,

Welcome to the Forum!
I am still deciding treatment for myself - it is quite a journey to do all the research.

Keep reading & and researching - i am sure you will find the answers you need.

Sincerely,
Sue

[Pim]

Dear all,
I had single dose CyberKnife treatment last week thursday. It was a fascinating experience to undergo a sort of science fiction virtual brain surgery and walk out of the clinique after 45 minutes without any symptoms.
After 2-3 days I now get loss of hearing due to swelling of the dead tumor that gives pressure to the nerves in the canal. This seems to be a inflammation reaction. Is this right and if so would a short cure (1 week of decreasing dose) of corticostereoidem (prednison) help to relieve the pressure and as such save the nerves?
Thanks for your reaction.
Pim

[suboo73]

Hi Pim! 

Yes, I think you should call your doctor and see what to do about this.
Even though I have not had any treatment yet myself, if I were you, I would be concerned about the hearing loss.

Take care and keep in touch.
I am sending prayers for you today!

Sincerely,
Sue

[Tisha]

Pim,

I had sudden hearing loss 3 weeks after my CK treatment.  I was put on steroids (decadron) immediately and my hearing came back.  Dr. Chang, Stanford, told me that is you don't do anything about your loss (however slight), the chances of it coming back later on , even if you were to do steroids months out, really decreases.  You need to take action immediately to have the best chance of saving hearing.   The steroids, especially the stronger doses, are awful for insomnia, but they work

Tisha

[Pim]

Dear Tisha,
I took prednisolon initially but switched to a more patient friendly homoeopathic medicine that worked fine. How long should I continue to take this medicine? I now don't have complaints from swelling and assume that the swelling disappeared. Can swelling come back in the furure and do you take these medicines for a longer period of time as a preventive remedy?
regards,
Pim

[Tisha]

Hi Pim,

I can't answer your question about the homeopathic medicines, sorry.  However, swelling can last quite a long time.  I had my 6 month MRI in July and the tumor was still swelled.  Dr. Chang said that I can have symptoms up to 18 months.  Sometimes the tumor swells and shrinks, sometimes it swells and never shrinks (but discontinues to grow).  So many different things can happen.

Did you ever have an audiogram done before your CK?  If so, you could have another one that will show you exactly what your puretone hearing is.

Best Wishes,

Tisha

[Pim]

Thanks, Tisha, for your good comments. I will follow your advice and have another audiogram made.
Regards,
Pim