How Dogs Could Help Humans Fight Cancer—and Vice Versa
By Charles Buchanan
Man's best friend can fetch, sit, and roll over. Now dogs may be about to perform their greatest trick: helping humans fight cancer—while treatments originally developed for humans are helping dogs that are suffering from the disease.
Examinations of genetic-based canine diseases reveal that 58 percent or more are comparable to human diseases, says UAB neurosurgeon—and veterinarian—Renee Chambers, D.V.M., M.D. "Investigating naturally occurring canine brain tumors provides a unique opportunity" to advance cancer research, she says.
Three years ago, Chambers began the process of turning that insight into a full-fledged research program. Now, thanks to a grant from the UAB Comprehensive Cancer Center, Chambers and her colleagues have begun analyzing naturally occurring brain tumors in pet dogs as part of the Alabama Comparative Oncology Network.
Previous research has shown that canine brain tumors known as gliomas spring from chromosomal mutations that may also be the source of glioblastoma multiforme, a malignant human brain tumor with a low survival rate. The canine and human tumors also occur at similar rates in both populations, and they share common patterns of progression and response to treatment.
Chambers's group is now collecting information from tumors found in pet dogs to determine "the reliability of certain breeds of canines as animal models for malignant glioma," she says. Short-nosed breeds such as boxers tend to develop non-malignant gliomas, while long-nosed breeds such as golden retrievers develop malignant tumors, Chambers explains.
Diagnosis and Treatment
Although cancer attacks the brains of dogs and humans in similar ways, pets obviously can't report their symptoms, says UAB neurosurgeon Renee Chambers. But there are several unusual behaviors that often accompany tumors in dogs, she explains.
Symptoms depend on the size and location of the tumor and are usually progressive, Chambers says. They may include behavioral changes, seizures, head tilt, circling, staggering gait, weakness, or paralysis.
A veterinarian will make the diagnosis by conducting a complete neurological examination and tests such as EEG, cerebrospinal fluid analysis, and brain imaging. Early treatment may include corticosteroids and anticonvulsants. Surgical removal of the tumor, possibly followed by chemotherapy and radiation, may also be indicated, Chambers says.
Labor of Love
The project represents a homecoming of sorts for Chambers, who worked as a veterinarian for five years in Birmingham before deciding to enroll at UAB's School of Medicine in the early 1990s. Her husband, who is a veterinary surgeon, practices in the Birmingham area as well. "The most interesting cases to me as a veterinarian were the neurosurgical cases I saw," Chambers recalls. "When I was still working as a vet I spoke to the head of neurosurgery at UAB and he invited me to come by and join rounds with his doctors, and I continued to do that while I was in medical school."
The combination of veterinary and human medicine makes Chambers a rare breed. "There's probably one person every few years" who pursues both M.D. and D.V.M. degrees in the United States, she says. "I've only met two myself."
When Chambers joined the faculty at the UAB School of Medicine, she became involved in research on (human) brain tumors with Yancey Gillespie, Ph.D., and James Markert, M.D., M.P.H. "One of my first publications was on viral therapy and brain tumors," Chambers says. "That's what initially sparked my interest, and it was a natural connection to look back at dogs."
Although Chambers's group is called the Alabama Comparative Oncology Network, it has already expanded to Mississippi; her goal is to build a national and even international catalog of outcomes data. "Canine and human tumors are so similar that it would be ideal to take every result you get from both species and add it to the database," she says. Collecting extensive clinical data "from companion dogs with naturally occurring brain tumors may allow us to catalog tumor signatures more quickly," expanding the knowledge base for human cancer and identifying potential targets for new drugs, Chambers says. "My goal is to establish and confirm the genomic similarities among humans and pet dogs so that they might share treatments that come out of this and other research."
Research candidates are currently drawn from pets who have been brought to the veterinary hospitals at Auburn University and Mississippi State University for treatment. After the dogs' tumors have been surgically removed, owners can elect to have clinicians treat the dogs using cancer therapies that have already been tested in humans. The owners pay for the costs of treatment. "Including pets with naturally occurring brain tumors in novel treatments being used in humans will increase the amount of outcomes data while offering these misfortunate animals compassionate treatment," Chambers says.