Tender Treatment for Rare Skull Base Tumors

MD Anderson Cancer Center
Date: 06/20/2011

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Lisa Garvin: Welcome to Cancer Newsline, a weekly podcast series from The University of Texas M.D. Anderson Cancer Center. Cancer Newsline helps you stay current with the news on cancer research, diagnosis, treatment, and prevention, providing the latest information on reducing your family's cancer risk. I'm your host, Lisa Garvin. Today, our subject is Skull Base Tumors and our guest is Dr. Franco DeMonte. He is a Professor of neurosurgery and head and neck surgery at M.D. Anderson and a nationally known expert on skull base tumors. Welcome Doctor DeMonte.

Dr. Franco DeMonte: Thank you very much.

Lisa Garvin: Let's start with an anatomy lesson. What exactly comprises the skull base?

Dr. Franco DeMonte: The base of the skull is the area of the skull where the brains sits upon. It's on top of the neck. It's the junction of the upper neck and the head itself and below it are the sinuses, the orbits, the neck muscles and above it are the nerves, the blood vessels of the brain.

Lisa Garvin: What sorts of tumors do we see arise in this area?

Dr. Franco DeMonte: Well they can arise from really three different locations. One is it can the tumors can arise from the structures within the cranium itself within the skull it also includes tumors from the lining of the brain, meningiomas which would be the most common, tumors of the pituitary gland, tumors of the nerves of the base of skull, acoustic neuromas would be a good example. Then they can arise from the bone itself. There are bone tumors that occur here, the most common being chordoma. And then any of the tumors from the sinuses or below the skull base can grow up to affect the skull base.

Lisa Garvin: Taken collectively, do we see a lot of skull base tumors diagnosed in the U.S. every year?

Dr. Franco DeMonte: Not particularly it's actually a quite rare tumor. The most common is the meningioma and those are--they make up one third of all tumors of the brain but in general the one's in skull base are much less common. They make up only about 40 percent of all meningiomas so they'd be the most common but still that's only 6 people per 100,000 per year. And the acoustic neuroma which you--I think you discussed in one of your programs earlier. It is maybe 3 per 100,000 per year. Most of these tumors are quite rare in the neighborhood of 300 in the United States per year.

Lisa Garvin: So it's probably hard to A, gain expertise give the rarity of cancers, and B, try to get a lot of research to move treatment forward.

Dr. Franco DeMonte: That's exactly right. I think the expertise is critical in order to optimally look after patients with this type of tumors. And I think people have realized this who deal with skull base tumors and have grouped themselves into skull base centers or centers of excellence that looks after these types of things. The research is problem because of the diversity of the pathologies involved. There are so many of these tumors where we see 1 or 2 a year where maybe only 300 we see in an entire United States a year. Very difficult to do surgery--to do research on your own for these types of things you have to involve yourself with collective groups across the country.

Lisa Garvin: And given the area, there are a lot of critical structures there, nerves, sinuses and so forth so you really have to know your way around.

Dr. Franco DeMonte: Yes. That's the other thing but skull base surgery it really goes beyond traditionally thought concepts of surgery and anatomy. As a neurosurgeon traditionally you never thought about anything below the base of the brain as a head neck surgeon you never thought about anything above the sinuses. But skull base surgery, yeah those where the tumors are. And a group of people over the years have dedicated their practices to understanding the anatomy below the base of skull; above the neck and those are the people who've joined together to create skull base surgery teams.

Lisa Garvin: And it seems pretty recent because when I came to M.D. Anderson 11 years ago there really was no skull base tumor program and then it started to grow within the last few years.

Dr. Franco DeMonte: There was me back at--when I joined in 1992 I was hired specifically to start working on skull base surgery but we really formalize things with Dr. Hanna joining us in head and neck surgery and Dr.Gidley in head and neck surgery I think that really marked the formalization of our program.

Lisa Garvin: Now let's talk about obviously you probably cannot do traditional open surgery in most of these cases. What are the surgical techniques that you are using now for treatment?

Dr. Franco DeMonte: The--it's a combination of traditional techniques that take advantage of the expanded and atomic knowledge that the surgeons who do this work have. Almost all of it is under the microscope--that so microsurgical removal these tumors especially peeling the tumors off, important blood vessels off, important nerves to maintain the function of those nerves. And the--and then we are looking at some noble ways of operating here we've done some laboratory work with robotics in trying to facilitate surgery in very deep quarters but that is not quite ready for primetime mostly because of the lack of appropriate design instrumentation. So it's still in the design phase for some of these instruments.

Lisa Garvin: Now do some of these tumors require adjuvant therapy such as radiation or chemo?

Dr. Franco DeMonte: Yes. Interestingly at M.D. Anderson and also the majority of my patients have benign tumors with skull base tumors so a lot of those the surgery is the definitive treatment. But there are some tumors--those that are malignant or those that are of low grade malignancy who do require radiation therapy or post [inaudible] chemotherapy.

Lisa Garvin: Are there any symptoms that arise from these tumors?

Dr. Franco DeMonte: The symptoms can be of all sorts. Some of the sinus tumors for example are just sinus congestion for it goes on and on and on. But others can present with double vision which is a quite noticeable problem. People with immediately complain about double vision. But some could be quite subtle, a little bit of facial and numbness, maybe a little bit of facial twitching, some with a little hearing loss. So they can be quite subtle for a long time. And because of that they can be quite large by the time we first see them.

Lisa Garvin: And what is the pattern of diagnosis? How do people end up with you? Is it maybe something that was found in another routine scan I mean are these diagnosed at a fairly early stage?

Dr. Franco DeMonte: They come in all sorts of different ways the--more and more now because of the availability of the CT and MR imaging we see a lot of patients were these tumors are identified simply because they had an MRI for a headache an earache, sinus congestion and the tumor is identified. The difficulty in those patients or the challenge is to put to the tumor into context with the patient and their symptoms. A lot of times with these benign tumors, our recommendation is simply not to intervene other than by watching them carefully over time. Many of them don't require treatment. Now that's the important of when you see somebody with a non symptomatic tumor. Others are quite symptomatic and come because they are having a lot of trouble.

Lisa Garvin: Do these tumors tend to come out in one piece? I think of glioblastoma where there are always pieces left behind or do these tumors themselves present any challenges for resection?

Dr. Franco DeMonte: Very much so. All of the benign ones, no real attempt is made to take them out in one piece. Because the goal there is to preserve neurologic function so you wanna take the tumors out leaving the critical neurovascular structures around the tumor intact. And that mandates a piecemeal or a bit by bit removal. The malignant tumors the bigger--of the sinuses and of the parotid gland those kinds of things ideally you would like to take them out in one piece. And we do try to do that because that is the ideal situation but we also take neurologic function into consideration in that regard and if there's any risk of causing neurologic problems in trying to take it out in one piece. Then we revert back to a piecemeal removal.

Lisa Garvin: Because you are dealing, I mean all the cranial nerves are there, I mean there's a lot of room for error I guess or causing you know long term effects down the road.

Dr. Franco DeMonte: Right? You know--and we're very cognizant of the fact that some of you know take--cutting a cranial nerve although occasionally necessary from malignancies is something we like to try to avoid.

Lisa Garvin: What do you see in the future? Are you honing surgical techniques? What sort of research are you doing?

Dr. Franco DeMonte: Well our surgical techniques continue to evolve. We spend a lot of time as surgeons in anatomy laboratories trying to work on new processes and new techniques. But I think more and more importantly I think over time the identifying individual characteristics on a molecular basis from tumor to tumor is gonna be critical in our ability to eradicate this tumors. I think for a lot of these benign ones and not a lot of time or money had been spent on them because their benign tumors and people they take a back a shelf to the malignant tumors but more and more attention is being paid to these benign tumors and if we can identify the individual molecular signatures that allow us to manipulate the tumors then we can avoid some of these high risk surgeries.

Lisa Garvin: What about intraoperative MRI, is that helpful at all in making sure you've got all the tumor out?

Dr. Franco DeMonte: In some circumstances pituitary tumors, it's quite helpful. Other tumors which are more affixed to the bony structure of the cranium, there's really no huge benefit having intraoperative MRI because we have intraoperative navigation on every operation. And in a rigid situation like the skull, the navigation is very, very precise.

Lisa Garvin: What about the status of imaging, I mean you're doing microsurgery, you're looking through a microscope. Are there any improvements that can be made there?

Dr. Franco DeMonte: Only if I get new pair of glasses I think but it--the microscopes are extremely high quality. Some of the stuff we do is with suture that is finer than the human hair. So I think from the point of view of actually seeing the tumor at the time the operation we do pretty well. And these are--unlike the tumors that are in the brain that it's very difficult to tell where the edges of the tumor most of these tumors are very well demarcated. They have very visible edges so we don't have the same problems that there are in operative and in surgery for brain tumors.

Lisa Garvin: Now I hate to generalize on a large subset of diseases but can you generalize about prognosis for these people, malignant versus benign.

Dr. Franco DeMonte: In general with the benign tumors, these tumors rarely shorten a person's life. The benign tumors tend to cause problems with function more than mortality. So our goal there is really to preserved function because usually the tumors are of a nature that they don't shorten life. The malignant tumors are different, they--we do very well with a lot of them but we have not solved the problem for some of these tumors and they do shorten people's life. We clearly take a more aggress approach with those tumors include radiations and chemotherapy trying to optimize the outcome.

Lisa Garvin: What would you to say to somebody who's been newly diagnosed with a skull base tumor? What would be your advice?

Dr. Franco DeMonte: The--because of the rarity of the problem and the rarity of the expertise necessary to deal with the problem. They really need to be evaluated and treated at a center of excellence for skull base surgery.

Lisa Garvin: Because I think a lot of--lot of people don't realize that M.D. Anderson does treat a lot of things that aren't cancer. Do you feel that perhaps patients aren't going to the right place because they say I don't have cancer, I don't need to go to a cancer center.

Dr. Franco DeMonte: Yeah I think sometimes the name cancer in the title of our hospital can dissuade some people from coming here but think there's no question that the expertise exists here that the--and we do see okay I think I mentioned earlier two thirds of my practice now is in--I see patients with benign tumors. And--so I think we serve patients with all sorts of brain tumor--skull base tumors very well.

Lisa Garvin: Great thank you very much. If you have questions about anything you've heard today on Cancer Newsline, contact askMDAnderson at 1-877-MDA-6789 or online at www.mdanderson.org/ask. Thank you for listening to this episode of Cancer Newsline. Tune in next week for the next podcast in our series.