Chat Transcript: Dr. Nicholson
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Transcript of Live Chat, from 9/24/01

Guest Host: Maurice Nicholson, MD : neurosurgeon, and the Medical Director of the Gamma Knife Center of the Pacific in Hawaii.
Moderator: Al Musella, DPM: President, Musella Foundation
Location: Musella Foundation Auditorium

  • What is the `Gamma Knife` and what is it used for?

    Gamma knife is a medical device utilizing 201 separate sources of cobalt 60 focused to a single point. It treats both malignant and benign brain tumors, arteriovenous malformations and other conditions such as trigeminal neuralgia, Parkinson's and epilepsy (certain types)

  • What role does the gamma knife play in the treatment of a glioblastoma? Should it be used before standard radiation, after, or instead of?

    It is often used as boost therapy after external beam radiation

  • Do you have any statistics about how useful it is as a boost?

    Currently statisctics are being gathered but the preliminary data show increased survival bearing between 3 and 6 months.

  • What is the best treatment for an acoustic neuroma, Gamma Knife or surgery?

    It is our experience that the control or cure rate is equal for both procedures however the complication rate is much lower for GK. there is a risk of death and infection w/ surgery whereas there's absolutely no risk of either w/ GK. The preservation of hearing and facial nerve function is better w/ GK

  • What guidelines are there for deciding between surgery and a blast of radiation for a meningioma?

    The decision for treatment varies from surgeon to surgeon.depending on their preferences, but also varies w/ the size and location of the tumor. Sometimes GK is the optimal treatment; sometimes surgery is and a certain percentages of cases could be treated either way. If there's residual tumor after surgery, it should be treated w/ GK

  • What are the long term effects of gamma knife radiosurgery for a benign tumor? I have heard of risks of dementia as well as causing malignant tumors? How big are those risks?

    There are no documented cases of dementia after GK therapy at the present time. The risk of causing malignant tumors is no higher than the occurrence of malignant tumors in the general population. There is no documented cases of malignant tumors having been caused by GK to our knowledge.

  • Can the gamma knife procedure be repeated if needed? How many times?

    Yes, GK can be repeated. usually only repeated once.

  • For brain mets: what would be the treatment of choice: full brain radiation, gamma knife radiosurgery or surgery? And what is the most number of tumors that can be treated in 1 person?

    The number of tumors varies depending on the size. In our center we haven't treated more than 9. Some other centers have treated up to 14. Sometimes GK can be used alone and sometimes whole brain radiation is used in conjunction w/ GK

  • What is the size limit of a single tumor to be able to use the gamma knife?

    Usually a maximum size of 4 cm is the upper limit.

  • Can you explain the difference between gamma knife, linac, peacock, proton beam and other forms of radiosurgery?

    Linac and peacock are basically are the same as they use linear accelerator. GK uses radio-active cobalt 60. proton beam is a different type of radiation and is only available in 2 or 3 locations in the U.S.

  • What is the difference between stereotactic radiosurgery and fractionated stereotactic radiosurgery?

    The term radiosurgery should only be used for single session. treatments and should not be used w/ the term fractionated. Fractionated means multiple doses are given over a period of time. This should be called fractionated radiotherapy.

  • How does the effects of gamma knife compare to brachytherapy, monoclonal antibodies / i131, and the new gliasite system?

    This is a complicated question.. all of these treatment modalities are different: GK uses external beams utilized in one session... brachytherapy requires implantation of radioactive materials.. that treats over a period of time... the other therapies are medical

  • Which works better for a GBM?

    At the present time, no treatment has been proven to be curative. All these are being tried in various combinations, in hope of finding a combination that will have longer term benefits"

  • How do you feel about radiation sensitizers - either for use with GK or standard radiation? Effective? Which one(s)?

    Clinical trials are under way but as yet no definite benefit has been found... with any sensitizer... research will be continuing in this area

  • What are your thoughts on patients taking vitamins - anti-oxidants - while undergoing radiation therapy?

    We have no thoughts pro or con

  • You said 4cm is the upper limit in size for a brain tumor. Is there a lower limit of size?


  • Can radiosurgery "cure" an acoustic neuroma, or just make it stop growing?

    It is our impression they are cured . There have been 10 year follow up demonstrating no growth... so the conclusion is that the tumor is dead and therefor the condition cured

  • What happens to the "dead" material in the brain?

    It is usually absorbed by the normal physiological processes that are present in the body.

  • Is it possible to use gamma knife therapy to remove a recurrent meningioma that is `wrapped` around the sagital sinus?

    We would have to see the MRI scan to give you a definitive answer

  • Is GK for GBMs considered experimental? Is it usually covered by most insurances?

    No. And it's covered by most insurance

  • How does GK help an AV malformation. (And what is an AV malformation - is it ""cancer"")?

    An AV malformation is a vascular abnormality - congenital in origin. It is not a cancer, but GK causes the AVMs to shrink and disappear over the course of 2 years usually

  • Do you see a future where brain tumors will be considered manageable and not the life sentence they are perceived to be now?

    We are hopeful that this will occur

  • What are the factors to consider in deciding between gamma knife and fractionated 'radiosurgery'?

    It would depend primarily on what is being treated. The GK is more accurate and is the treatment of choice for most lesions that are small or in critical areas. Unfortunately some centers don't have GK and therefore recommend fractionated radiosurgery

  • Do you think that gamma knife will become the first line of treatment for meningiomas of appropriate size in the future? (Or is it now?)

    Personally - I feel it will, but at the present time, many surgeons continue to recommend surgery .

  • The people who use proton beam radiosurgery say their treatment is more accurate near critical areas. How do they compare?

    To the best of our knowledge the accuracy is not much different.

  • How long has GK been available for brain tumor patients, and how many GK centers are there in the USA?

    It has been available in the U.S. since 1987. There are about 42 centers in the U.S.

  • How long after standard radiation is the best time to use the GK for a gbm? And would you use it as a boost even if there is no tumor left on scans?

    If there's no tumor on the scan then there would be no target to treat. Usually GK boost is given at the end of the external beam radiation, sometimes it is given concurrently

  • How frequently do you see problems with radiation necrosis after GK radiosurgery? And what can be done for it? Any new treatments for radiation necrosis?

    Radiation necroses is sometimes seen in the middle of tumors that have been treated. Usually it's not a problem but may require steroid medical treatment and occasionally surgery is needed to remove the necrotic tissue. This doesn't occur very often and in our experience less than two percent

  • How about hyperbaric oxygen? Is there a place for it's use in radiation necrosis?

    There is some evidence that it is useful, and therefore should be tried if the patient is having a problem related to necrosis

  • Has GK been used for oligodendrogliomas? Any statistics?

    It has been used for well localized tumors. It has been used w/ external beam radiation

  • Can you treat brainstem gliomas? How about Children with other tumors - how old was your youngest (and oldest) patient?

    Yes, we can treat brain stem gliomas. Our youngest has been 2-years-old. We can't remember the age of the oldest

  • Have you had any success using GK for Trigeminal neuralgia and Parkinson's disease?

    Yes, we've had a lot of success for treating TN. We have done a few Parkinson's patients with good results in treating the tremors

  • Would you consider the GK to be the most advanced form of radiation therapy for brain tumors? If not - which one is?

    In our opinion there is no better type of radiation therapy for small irregular tumors. Obviously for certain larger diffused tumors, external beam radiation is the best. The answer to your question varies depending on the tumor being treated. There are some tumors being treated with proton beam therapy but that is very expensive and not available to most patients.

  • Can GK be used to treat seizures?

    Yes, for certain types of seizures. Medial temporal lobe seizures can often be treated w/ GK rather than performing a partial temporal lobectomy

  • Can you have GK radiosurgery after having gliadel wafers implanted?

    Yes - this would depend on the tumor size and condition of the patient

  • Do you know of any GK centers in Austrailia?

    There are none

  • Where would the closest one be?

    The GKCP services patients from Australia. There are centers in Japan but the GKCP recognizes the circumstances of Australia and works w/ them on a case by case basis

  • What is GKCP?

    It is: Gamma Knife Center of Pacific, the name of our center in St. Francis Medical Center in Honolulu, Hawaii

  • Would Gk be advisable for an optic glioma, posterior to the chiasm.

    GK could possibly be used - we would need to see the MRI scan

  • A patient asks: She has a recurrent gbm described as a ""plaque like"" on the surface of the brain approx. 2cm - does that sound like a GK case?

    On the basis of her description, it certainly can be treated by GK, however the MRI would have to be reviewed before a definitive decision can be made. We'd be happy to review the films if they want to send it to us at no cost to the patient

  • Can you give us the phone number and website address of the GKCP?

    1-808-547-6865. ,, and

  • What is a chordoma? And can it be treated with GK?

    Chordoma is a tumor that is usually slow growing. It occurs at the base of the can be treated w/ a GK. They actually arise from bone, presumably from notochordal remnants

  • If a meningioma that was treated with the GK recurrs, would it be better to repeat GK, or use a different form of radiosurgery?

    If the growth is outside of the area that was treated, then GK could be used again. The original treatment plan would have to be reviewed. If the tumor recurred w/in the area treated, then a fractionated radiotherapy would probably be best

  • Getting back to brainstem gliomas: do you have any statistics on how useful GK is? Do you have to do a biopsy first to determine the exact type of tumor?

    Usually, a tissue diagnosis is made. The exact statistics we don't have at hand... we do know that the results of GK treatment seem to be better than other forms of radiation.

  • Are there any immediate effects from a GK treatment session? (does it hurt??:) Does it involve an overnight stay? How long off from work is needed?

    Ooccasionally a patient will have a headache, or slight discomfort at the pin sites for a day or two. Usually only an aspirin or tylenol is needed for relief. This is usually an outpatient procedure and only occasionally is a patient kept overnight for observation. When the GK is being administered, there is no pain, the patient feels nothing.

  • How long does it take - from the time you get to your center to the time you leave -for a typical treatment?

    It depends on what is being treated. If an arteriogram is needed or not, etc.. The average time is 5 hours.

  • Can you treat a pituitary adenoma? How would you decide between radiation or surgery?

    Pituitary adenoma are treated w/ GK.. sometimes w/out prior surgery.. and often after a transphenoidal surgery has been done

  • Would a GK treatment disqualify you from most clinical trials (for a gbm)?

    It would depend on the clinical trial.

  • Can gamma knife radiosurgery be done fractionated?

    A few centers have done some fractionated GK, but as a rule, No.

  • How many brain tumor patients are treated at your center each year?

    We don't have the total for the last year but in September we are treating 7 patients.

  • A patient asks: my neurosurgeon says to have surgery for the acoustic neuroma, but the radiation oncologist says stereotactic radiosurgery. How do you decide? (60 year old woman in good health otherwise)

    As a neurosurgeon, I would recommend GK rather than surgery. In my opinion there is minimal risks for GK and definite surgical morbidity w/ surgery and even a remote risk of mortality. Unless the tumor is too large (3cm +) I would definitely recommend GK. Our results and the literature currently also has such good results there is no good reason to undergo the risk of surgery.
We have reached the end of our hour! Thank you Dr. Nicholson for participating!

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