Acoustic Neuroma Patient Archive:
Exclusive Interview with Dr. Lederman


Dr. Gil Lederman is a renowned pioneer of modern fractionated stereotactic radiosurgery treatment for acoustic neuroma. You can find stories from several of his patients in the FSR section of the AN Archive's Patient Directory.

As one of his many patients with a very successful outcome, I am delighted that Dr. Lederman has found the time to answer some of the questions frequently voiced by the Archive's visitors. Dina Goldin, the Archive's Founder and Editor-in-chief, compiled these questions for the interview.

Chris Ottewell
Bristol, England May 2001

Q: Dr. Lederman, by way of introduction perhaps you can you tell us how many Acoustic Neuroma patients you have now treated and what is your success rate?

A: We have currently treated four hundred patients with Acoustic Neuromas using our hypofractionated technique, with an overall success rate of 99%.

Q: We always advise patients to question their doctor's responses to ensure that the doctor means what the patient thinks they mean. So perhaps you can explain to us the definition of "success" as used at SIUH in connection with your acoustic neuroma treatment?

A: "Success" is defined as cessation of growth, shrinkage or disappearance of the tumor.

Q: Thank you.  I know from the Archive mail that people from all over the world have been treated at SIUH. Perhaps you can list the countries from which people have come specifically for your Acoustic Neuroma treatment?

A: We have obviously treated patients from around the United States.  And throughout the world.  There currently are "Acoustic Neuroma clubs" in the United Kingdom and Israel, but patients have arrived at Staten Island University Hospital for treatment from Malaysia, Singapore, Australia, Japan, Brazil, Argentina, Venezuela, Honduras, South Africa, Jordan, Lebanon, Egypt, India, the former Soviet Union, France, Great Britain, Germany, Italy, Canada, etc.

In fact, we have so many patients coming for treatment that we have built an apartment building for thirty-five families. The housing rates have been kept remarkably low, to make the treatment most affordable for all. We also have some airlines that have flown our patients in for free or at lower cost, to help extend the benefits of our treatment to those seeking such care.

Q: What sort of age range has your treated? Indeed, are there age-related issues for acoustic neuroma treatments (are some treatments more appropriate, say, for younger vs. older patients)?

A: Age range is 11 to 88 years, with a mean of 54 years and median of 53 years. 

Personally, I believe that all people with Acoustic Neuromas seek similar benefits. That is, successful treatment, avoidance or minimization of complications, the maintenance or improvement of hearing, while maintaining facial and trigeminal nerve function. This is obviously true for adults as well as children.

Q: You have a reputation for treating more large tumors using FSR than anyone else. Can you tell us a little about your experience? For example, do you have any statistics specifically for this patient group?

We have treated 49 patients with 51 [large] tumors. Follow-up evaluation ranged from 6 to 85 months or a mean of 28 months. Our success rate is 98%. As I mentioned we define success as cessation of growth, decreased size and or disappearance.

In this group, 29 tumors or 57% decreased in size, 21 tumors or 41% showed cessation of growth and 1 tumor (2%) increased in size. In 32 patients, hearing showed improvement in 8 or 25%, remained stable in 18 or 56% and worsened in 6 or 19%.

Q: What are the current size limitations on FSR eligibility of Acoustic Neuroma patients?

A: I believe that patients with all size tumors, large as well as small, seek the similar advantages of fractionated radiosurgery: non-invasive, painless, outpatient treatment without anesthesia or hospitalization while having the benefits described above.

Our experience currently has treated patients successfully with tumors up to thirty-seven cubic centimeters. These tumors are exquisitely sensitive in general to radiation.  Patients with larger tumors tend to have a higher incidence of hydrocephalus, an increased fluid pressure within the brain. This, in our experience, has been treated successfully with shunt placement. The shunt bypasses the fluid and allows for a secondary route of egress. In patients who present to us with hydrocephalus I encourage placement of the shunt followed by fractionated radiosurgery.

Q: What about those patients whose Acoustic Neuromas were not diagnosed until they were too large to be eligible for radiosurgery? What kind of a treatment protocol would you recommend for them?

A: Regarding patients having too large an Acoustic Neuroma for treatment, I do not believe this really is a category that exists. Earlier size limitations were placed on patients who were considering treatment with Gamma Knife. The Gamma Knife collimator size (or beam size) is much smaller than the vast array of collimator sizes at Staten Island University Hospital. In fact, unique collimators are developed to assure complete coverage of the tumor while minimizing harm to adjacent tissues.

Another advantage of fractionated radiosurgery over Gamma Knife treatment is that our dose tends to be much more homogenous or nearly equal across the tumor. We routinely treat patients at the 90% isodose line meaning that in general the maximum warm spot is only 10% [more radiated].  That is in stark contrast to the Gamma Knife experience, where usually the patients are treated at the 50% line meaning that the tumor within the center of the treatment is receiving twice the prescribed dose.

Obviously there is not only tumor but also healthy nerve in the center of the treatment field. I believe that is a major reason why our success rate, especially for maintenance of hearing, is better than with the Gamma Knife experience. That is true both for large as well as small tumors.

Q: What other considerations besides size affect a patient's eligibility for FSR? For example, does the placement of the tumor inside the canal (intracanicular acoustic neuroma) vs. outside make a difference?

A: We have not seen differences in outcome based upon tumor location. Tumors within the canal are generally further from the brain stem. These patients usually present with hearing and balance symptoms. They are usually immune to the effects of the tumor's pressure on the 5th and 7th cranial nerve namely the trigeminal and facial.

With our great success rate failure is exceptionally unlikely. No patient with an intercanalicular tumor has failed and only three of the remaining hundreds have required further intervention.

Q: We sometimes hear from surgery patients whose tumor turned out to be much larger (according to their surgeon) than measured on an MRI just weeks earlier, say, 4cm vs. 2.5cm. This seems to contradict what we know about Acoustic Neuroma growth rates, and also seems to imply that radiosurgery's reliance on MRIs for guiding the treatment course may be dangerous.  Should we be worried about such cases?

A: When numbers fluctuate greatly it is more likely the observer rather than the tumor that is the culprit.

There are many, many ways to measure Acoustic Neuromas. Some measure the greatest dimension in any way it appears on the scans. Some measure the component of the tumor into the canal if it exists. Some measure straight anterior/posterior, superior/inferior or other. Thus it is very difficult for patients to rely on different radiologists at different times to give an equivalent reading.

Our group relies upon highly qualified neuroradiologists and experienced radiation oncologists who have performed fractionated radiosurgery to measure the tumor in an equivalent and similar manner each time.  Furthermore we like to see all the films at the same setting so that we can be confident of the comparison.

We do not rely on old scans. Patients are obviously planned at the time of treatment. It is true that some patients, especially those with NF2 can have rapidly growing tumors, therefore, dependence on an old scan is unreliable.

Q: We've heard that for NF2 patients, the tumor cells respond differently to radiation. Are the considerations for NF2 patients, when making their treatment decisions, the same as for other Acoustic Neuroma patients, or different?

A: We see many NF2 patients because of several reasons. One reason is the often catastrophic results of surgery. Many patients with NF2 come to us after surgery on one side, with a growing tumor on the opposite side and obviously only hearing in that second ear. These patients come to us both for successful outcome and, as importantly, maintenance of hearing.

I believe the benefits of fractionation, which have been known for eighty years in the field of radiation, are especially important for Acoustic Neuroma patients, and more so in those with NF2.

Q: What are the expected outcomes for NF2 patients vs. others? Can you tell us more about your experiences in treating NF2 patients?

A: Generally NF2 patients come for evaluation with larger tumors and of course bilateral tumors. Many patients have had surgery on one side, which has most commonly taken away all the hearing and often created other side effects related to the intervention.  Patients with NF2 tend to have larger tumors and tend to have worse hearing. 

The fact that approximately 20% of our patients have documented improved hearing is an inspiration both to our patients and us. Fractionated radiosurgery is more "gentle" on the tumor and nerve than a single higher dose shot of treatment.   It should be noted that our treatment dose is considered the lowest biologically effective dose worldwide. This is a key point.

A similar point is that many radiology groups compare treatment results to MRIs done months or sometimes even years before. This can lead to alarm by physicians for their patients. I believe it is critical to analyze scans from the time of treatment henceforth in determining the effectiveness of outcome. [As I said,] we do not rely on old scans.

NF2 patients frequently have multiple other tumors some of which are symptomatic. Nevertheless the success rate using fractionated radiosurgery is exceedingly high. We have surgeons and even Gamma Knife surgeons who send us NF2 patients for fractionated radiosurgery, in an effort to avoid the complications associated with other methods of treatment.  And we have what appears to be the highest hearing preservation rate.

There are many reasons for NF2 patients to consider fractionated radiosurgery for their tumors. I believe the low complication rate and the likelihood of maintaining hearing are amongst them but as well the avoidance of surgical or pin into the skull intervention are important as well

Q: As you probably know, the fear of treatment-induced malignancy prevents some Acoustic Neuroma patients from considering any form of radiosurgery. You, as a cancer specialist and Director of Radiation oncology at SIUH (as well as a pioneering Acoustic Neuroma doctor), are probably better placed than anyone else to explain the issues and put them into context.

First of all, is there any statistically significant malignancy risk at the dose levels you use?

A: The likelihood of malignancy is considered very, very low. I have never seen a treatment-induced malignancy from fractionated radiosurgery. There have been induction tumors reported from the gamma knife experience.

Obviously no patient and no physician wants to see treatment related complications, especially tumor induction. As I described before, I believe that fractionated radiosurgery is much safer than Gamma Knife or surgery. Surgery has treatment related morbidity and mortality, which is immediate and immense.

Q: How can you be so confident of your treatment? We thought that there is not enough long-term FSR experimental data to be sure. Can the data gained from 30+ years of Gamma Knife experience be used here? And how about data from other FSR centers?

A: Yes it is true there is more than thirty-two years of experience with Gamma Knife. The problem is that many different doses have been used over those years. In fact, until recent times, exceptionally high doses were used, doses that are no longer considered in modern treatment. Therefore, all investigators must start to evaluate all their data once again when new treatment approaches are begun. That is one of the critical issues here.

All our patients have received the 2,000 rad in hypofractionated technique. All of our patients are followed. We follow all our patients on a regular basis. Our staff contacts our patients for follow-up results, MRI scans and hearing tests. We are most eager to follow every patient treated over the years.

Some centers use different doses for each patient. Other centers are using   significantly higher doses. The main different fractionated approaches include 5,400 rad in 30 fractions, 2,500 rad in 5 fractions and now 1,800 rad in 3 fractions, as compared to ours. Relative to the hypofractionated approaches, our data is the most extensive and mature of those approaches. When 99% of our patients are successfully treated with hearing preservation being seen in 94%, I doubt other approaches will be as positive.

Even our data shows: when 500 rad is given daily for four days the hearing preservation rate is only 65%. I don't believe there is any way that 500rad can be given daily for 5 fractions for a total dose of 2,500 rad and have anything but less than good hearing outcome. Furthermore that experience has fewer patients, less mature data and a higher trigeminal neuropathy rate.

The proof of the pudding is in the eating, and our patients in general are doing exceptionally well. Our data is strong. We have done statistical analysis of our data to show that it is not a fluke but it is true mathematically and scientifically.

There are always a few patients with difficult stories. I believe that the difficulties have been blown out of proportion while the overwhelming vast majority of people return to their normal lives and activities. In the first Gamma Knife experience it was reported that about a third of the patients didn't work after treatment. That is nowhere near our experience at any time. Many of our patients call what they experience a "treat", not a treatment. It is a treatment, but it is very well tolerated and very successful.

Q: We heard that you now believe that a minimum 48 hours between treatments gives better hearing preservation rates. Is that right?

A: In the last year we have analyzed our data, showing that treatment given on alternate days dramatically improves the likelihood of hearing preservation. This is true for both 400 rad times 5 or 500 rad times 4. Overall, the best hearing preservation rate remains 400 rad on five treatment dates separated by at least forty-eight hours. This flies in the face of what was felt to be true by radiobiology criteria. Most radiation oncologists had believed that eight hours was enough between fractions. Again, observations of patients are stronger than theoretical possibilities.

Q: How do you see as future of Acoustic Neuroma treatments?

A: I believe that hypofractionated radiosurgery for Acoustic Neuromas could well be considered the standard of care. I do not believe that surgery is an important part of treatment and in fact believe that in the future it will be considered antiquated for the vast overwhelming majority [of AN cases].

I believe that our approach has outcomes which are enviable and will stand the test of time. We now have patients in their ninth year of follow up evaluation after treatment and they are doing as well as those at any other point, meaning superb. Our data has been published and presented at national and international meetings. I have lectured on radiosurgery from Abu Dubai in the Persian Gulf to Japan and many points in-between.

For those with newly diagnosed Acoustic Neuromas, I would urge them to speak with others who have gone through the various approaches. We have a list of names and phone numbers of those who have agreed to speak and answer questions. I personally attempt to answer all my phone calls, letters and E-mails from those with acoustic neuromas in an attempt to provide current state-of-the-art information. We have a panel of experts to evaluate each case on an individual basis to assure not only proper treatment but also proper diagnosis -- a most critical issue.

For someone with a newly diagnosed acoustic neuroma one can feel confident about the treatment at Staten Island University Hospital. Our approach and team is experienced and proven. There are hundreds of patients successfully treated over years as a testimony to the multiple benefits. All our patients therefore go through this approach.

Q: Thank you for taking the time to give us this interview. We hope it will resolve some common questions that newly diagnosed Acoustic Neuroma patients face in their decision-making.

transcribed by Dina Q Goldin
August, 2001

Last Edited: Friday, May 02, 2003