New Radiosurgery Technology Available To Help Cancer Patients at UF's VMTH
by SARAH CAREY
Dorothy Schweitzer and Cindy Schweitzer.
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Six years ago when
she was still a puppy, Cindy was rescued from abandonment and starvation. But
that wasn't the end of the Dunnellon dog's troubles. When she developed a tumor
two years later, salvation came from a pioneering form of radiation therapy
developed at the University of Florida.
With one massive
but precisely targeted dose of radiation directed at the life-threatening tumor
above her eye, UF veterinarians ensured that the dog, owned by Dorothy Schweitzer,
would again prevail over adversity.
"To my knowledge,
she was the first dog in the world with an extracranial tumor to have radiosurgery
delivered by a stereotactic linear accelerator," said Tim Cutler, M.V.B., an
ophthalmology resident at UF's College of Veterinary Medicine.
Through a
unique partnership between UF veterinarians and scientists based at the Evelyn
F. and William L. McKnight Brain Institute of UF, small animals with tumors
are now able to received some of the world's most advanced radiation planning
and treatment. While the animals receive top-notch treatment, the partnership
also furthers ongoing research to improve cancer treatment for people.
"So far we've done a total
of 22 animals, including both dogs and cats," said Nola Lester, B.V.M.S., a
clinical instructor in radiology with the UF veterinary college. "About 20 of
those cases have been treated over the past two years, and most have been patients
with brain tumors, and other tumors in the head region."
Known as stereotactic radiosurgery, the original
method has evolved as the treatment of choice for humans with certain types
of intracranial tumors since its inception more than a decade ago. In 1988,
Frank J. Bova, Ph.D., and William Friedman, M.D., initiated radiosurgery treatments
using their patented system known as the LINAC Scalpel. This system assists
with localizing, planning and treating intracranial tumors using a specially
designed adaptation of a medical linear accelerator. Recently, Bova and Friedman
have developed an additional method that uses a three-dimensional ultrasound
guidance system to pinpoint tumor location and target radiation beams precisely
to tumors in internal organs.
"Radiosurgery has been used to treat certain
brain tumors and arteriovenous malformations in people for many years," Lester
said. "We have been able to transfer this technology to animals and are using
it to benefit our cancer patients."
"As far we know, there are no other veterinary
facilities in the country, and probably the world, that are doing this procedure
on animals," Lester said. "We are extremely fortunate to be in such close proximity
to the Brain Institute and to have people there who are willing to collaborate
with us."
She added that stereotactic radiosurgery
allows a higher dose of radiation to be given in one session than would be administered
during more traditional radiation therapy - and often with better results.
Another advantage is that animal patients receive a
single dose of anesthesia rather than several that would be administered over
a period of time during traditional fractionalized therapy, in which several
doses of less potent radiation are given in a more general region of the area
surrounding the tumor.
"Pet owners having the procedure done here need
to bring their pets to the UF Veterinary Medical Teaching Hospital one time,
which can be a big advantage, particularly for those who would be traveling
long distances," Lester added.
The procedure is also being used at the veterinary
teaching hospital to treat vaccine-associated fibrosarcomas in cats and osteosarcomas
in dogs, she said.
"In people, a stereotactic head frame was built
to aid radiologists in obtaining their up-to-the-minute computer images, but
we found it just didn't work well in dogs and cats," she said. "So we adapted
a method using a 'bite plate' - a dental mechanism - that works much more effectively
in animals."
Lester stressed that the procedure is at times
extremely effective, and at times, less so.
"In some cases, we have seen fantastic results
and the tumor completely disappears. In others, this is not the case. So we
are still in the early stages of figuring out what responds well and what doesn't."
The procedure costs approximately $2,200, roughly the
same as for traditional veterinary radiation therapy. Certain animals may be
eligible for a $700 UF subsidy, in addition to free follow-up care and imaging.
Dorothy Schweitzer's dog, Cindy, though successfully
treated for her eye tumor, subsequently developed an unrelated mass in her spleen,
which was surgically removed at UF.
"She is really the miracle dog because she is now considerably
beyond the average survival time for both of the unrelated cancers she had,"
Cutler said.
For more information about the UF veterinary
college's cancer treatment program, contact the Small Animal Hospital front
desk at (392) 4700, Ext. 4700.
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