A radiograph (x-ray) may reveal that an animal has nodules in its lungs, but is limited as a diagnostic tool because the nodules may indicate tumors, or may be scar tissue from an old infection. Another challenge that veterinarians face in diagnosing and treating cancer is measuring the response of the illness to the therapy. Combining the PET scan technology with computed tomography (CT) scans or magnetic resonance imaging will allow MU veterinary oncologists to co-register an abnormality, effectively creating a three-dimensional image that shows not only the size of a growth, but also its metabolism.
“Sometimes a tumor is responding to therapy, but it doesn’t immediately shrink, and it may never shrink, but it may have been neutralized and no longer poses a threat,” said Kim Selting, a veterinary oncologist at the MU Veterinary Medical Teaching Hospital. “The PET Scanner allows us to look at a tumor and determine that while the growth may still be present, the therapy has effectively killed it.” Conversely, if a tumor is still showing metabolic activity, a clinician may consider a different course of treatment, such as adding or changing the chemotherapy protocol. PET scans are also useful in seeking out cancers that may be hiding somewhere in an animal’s body.
The PET Scanner can also be used by other veterinary services within the MU Veterinary Medical Teaching Hospital. The scanner can be used to look for infections, evidence of fracture healing and abnormal bone activity, and the source of seizure activity. In addition to advancing patient care, veterinary PET scan capability is expected to put MU in the forefront to attract new research studies and cancer therapy trials focusing on translational medicine. The availability of the PET scan technology, as well as both a Comparative Oncology Program and Comparative Internal Medicine Laboratory, has already attracted a new two-year study to test a new immunotherapy. The therapy uses detoxified bacteria to stimulate the immune system to control tumors without the use of chemotherapy drugs, explained MU veterinary oncologist Jeffrey Bryan. The agent has shown promise in treating dogs with carcinomas, skin cancers and some oral cancers.
“We will be selecting dogs for the study, evaluating them with the PET scan and treating them,” Bryan said. “Our Comparative Internal Medicine Lab will evaluate the immune response in the study dogs. This project could not have come together in this way without the PET scanner, and MU is one of only a few institutions that could conduct this trial. Having this PET scanner also positions us to participate in select trials through a national trials consortium to which we belong (the Comparative Oncology Trials Consortium through the National Cancer Institute). Those trials are designed to evaluate therapies in dogs with cancer that are destined for translation to use in people. That way, both animals and people can benefit from the same cancer therapy.”
Stan and Judy Stearns, who donated the scanner, know all too well the emotional toll cancer can take on the family of an affected pet. Their St. Bernard, Gabriel, was diagnosed and ultimately succumbed to bone cancer leaving them with a desire to find better treatments for this disease. Having worked with biomedical instrumentation for many years, Stearns has invested substantial time, effort, and resources into developing tools to treat bone cancer. His generosity has extended to many veterinary schools across the country as he has supported unique needs of individual oncology programs.