A novel 2-year-old marriage between animal and human medical specialists is helping to provide the pinpoint accuracy necessary to successfully treat head and neck tumors in dogs.
Specialists at the Washington State University College of Veterinary Medicine and the University of Washington School of Medicine are collaborating on state-of-the-art therapy that blasts a tumor with radiation while minimizing damage to surrounding tissue or organs.
"This is literally cutting-edge technology linking human and veterinary medicine," said Dr. Pat Gavin, WSU veterinary professor and radiation oncologist. "What we're doing for these dogs needing treatment is ahead of human medicine, but we'll both benefit in the long run. We do applied research to help validate the new approach to allow this treatment to be used in humans eventually."
Brain tumors appear in about 14 of every 100,000 dogs. WSU researchers recently reviewed the records of 97 dogs with brain tumors that were presented for evaluation. Thirty-six breeds were represented.
Veterinarians take a variety of approaches when a dog is diagnosed with a brain cancer. Surgery may be possible in a few cases, and chemotherapy may be of benefit in select cases. Steroids are often administered; they reduce the swelling that accompanies the tumor and may provide relief of the symptoms for weeks to months.
Radiation Therapy Is Best
Radiation therapy is generally considered the best therapy for many cases and the median survival is one to two years with a high quality of life. When a veterinarian refers a dog to WSU, the animal undergoes magnetic resonance imaging (MRI) and CT scans to pinpoint the tumor's location, size and configuration. Gavin and fellow veterinarian Dr. Hege Kippenes then evaluate the findings and plan a course of treatment, including the radiation dosage.
At that point, the information and the images are sent 300 miles via the Internet to Drs. Mark Phillips and George Larramore of the Department of Radiation Oncology at the University of Washington. Their job is to devise an intricate battle plan based on a computer program, called Prism 3D, which runs a linear accelerator (a high-energy radiation-producing machine).
Intensity Modulated Radiation Therapy
The treatment is called Intensity Modulated Radiation Therapy and its object is to focus radiation precisely by directing numerous revolving radiation beams onto the tumor. Kippenes says the goal is to deliver 100 percent radiation to the tumor and less than 50 percent to surrounding tissue.
The task is complicated by the fact that dogs can require 18 to 21 treatments over three to five weeks – and they must be identically positioned for each treatment.
To help assure accurate positioning, dogs are placed in a specially contoured bean-bag-type vacuum-body air cast directly beneath the linear accelerator. Each dog is lightly anesthetized with gas. Treatments typically last 5 to 10 minutes.
"The beauty of this," says Gavin, "is that when the treatment is completed, the animal will recover in two minutes and walk out of the treatment on its own."
The WSU hospital treats three to four cases monthly, while veterinary cancer specialists in the Portland and Seattle areas have four- to six-week waiting lists for patients. Once a dog is presented for its first diagnostic visit, he can be put on a relatively fast track for treatment: He can often start radiation therapy within a week. Treatment costs range from $3,000 to $3,500.
There are no figures yet on the success rates of the treatment. The program is only in its infancy and WSU receives dogs in many stages of cancer, making it impossible to draw conclusions at this point. Future studies will examine the issue.