From the Editor: Comparative Oncology Research Uncovering New Approaches

Howard L. Kaufman, MD, FACS

On some days I think that my dog is my best friend. This is certainly a widespread belief and it reminds me of a patient that was admitted to the Intensive Care Unit several years ago. The patient was not doing well and had a single wish, to see his dog again. Without my knowledge, our enterprising house staff in collaboration with at least a few ICU nurses hatched a plan to bring the patient’s dog into the unit through an open window. You can imagine the surprise on the following morning when we found a dog in the room with one happy and physiologically improved patient. This experience, among others, led to our hospital developing the country’s first open pet policy, in which patients admitted to the in-patient units could arrange for visits from their dogs or cats during their hospitalization. Of course, we now more fully understand the profound impact animals can have on human health. Many medical centers utilize animal assisted therapy to help people cope with the many consequences of a cancer diagnosis or adverse effects of cancer treatment.

Certified pet therapy programs provide patients and their families with comfort, relief, and a distraction from pain, nausea, discomfort, and stress. Exposure to pet therapy has demonstrated significant reduction in stress levels and blood pressure, increases in mood, energy levels and immunity, and can lessen perceived pain. The presence of an animal can also promote a sense of companionship and distraction, which can overcome frequent feelings of isolation and anxiety.

There are an estimated 65 million dogs and 32 million cats in the United States that are living in human households as pets. These pets often enjoy a prominent role in people’s lives and serve as loyal companions. As many people know, our pets are also susceptible to many diseases, some of which are shared by humans. In fact, 12 million dogs and cats are diagnosed with cancer every year in the United States.

While certain breeds may be more predisposed to certain cancers, it is not clear exactly why the cancer rate is so high and how similar or different canine or feline cancers are to human cancer. The emerging field of comparative oncology is designed to study the biology of cancer in different species in order to identify mechanism of tumor initiation and progression, as well as therapeutic targets, which may have implications for a better understanding of human cancer and cancer therapy.

To help spur this effort, the National Cancer Institute established the Comparative Oncology Program in 2003. The program provides new tools for treating canine and feline cancer while establishing innovative pathways for human cancer research. The program has helped develop a national canine tumor registry, promotes clinical trials for dogs with cancer and is now bridging into collaborative research opportunities with human translational investigators and clinical oncologists.

Spontaneous cancers in companion animals appear to share many characteristics with human malignancies, especially in melanoma, soft tissue and osteosarcoma, prostate cancer, breast cancer, non-Hodgkin’s lymphoma, head and neck cancer and virally-mediated tumors. In addition to studies of genetic mechanisms that promote cancer development and progression, animals often share similar environmental risk factors, which can be exploited to more rapidly define how such factors might influence human cancer development. In contrast to inbred murine models of cancer, companion animals provide a more physiologically relevant outbred system for conducting biomarker-based and therapeutic investigation.

Comparative oncology research is also leading to new approaches in cancer drug development by helping to identify novel pathways for therapeutic targeting and establishing appropriate dosing, safety, and initial therapeutic profiles of new agents. This work has also provided tangible benefits for the pets. In recent years, for example, a vaccine (Oncept), based on a xenogeneic tyrosinase DNA plasmid, was approved for the treatment of canine melanoma. Initial clinical studies in humans were translated to dogs.