Advancing cancer treatment

A Q&A with small-animal oncologist specialist Dr. Stephen Withrow
Mar 01, 2011

Dr. Stephen Withrow is a professor of surgical oncology and the Stuart Chair in Oncology at the College of Veterinary Medicine and Biomedical Sciences at Colorado State University in Fort Collins, Colo. He is also the associate director of the university's Animal Cancer Center, which he helped found. And he is the co-author of the textbook Small Animal Clinical Oncology (Saunders, 2006).

Helping humans through animals: Dr. Stephen Withrow, with Angela, a cancer survivor, and Jacki, one of Dr. Withrow's Labrador retrievers.
DVM: Your special interest is multimodal cancer treatments in animals as a model for humans with cancer. And I understand you initially became interested in that topic when you were an intern in New York City and then again while doing a fellowship at the Mayo Clinic in the 1970s. Can you tell us about those experiences?

Withrow: I graduated from the University of Minnesota in 1972 and was working as an intern at the Animal Medical Center in New York. We were encouraged to attend rounds in any of the area hospitals. I went to Memorial Sloan Kettering, and it was there that I became aware that veterinary medicine could have a significant influence on human health.

During this time, I had very good mentors, including my service chief, Dr. Bill DeHoff. My mentors encouraged me to take three months to complete an outside rotation. I chose the Mayo Clinic in Rochester, N.Y., and my time there was a real eye-opener. I learned that with surgical removal, chemotherapy and radiation therapy, there was no reason—short of money—why some of these human treatments couldn't be used in veterinary medicine. All we lacked was education on these techniques.

Eventually those of us interested in surgical oncology formed societies, and then we had certifications and clubs. Eventually, we helped to build this idea of translational medicine. A lot of people see translational medicine as something going from mice to people, but we know that oftentimes dogs and cats should be in the middle of those basic discoveries. So it should be from mice or rats, to dogs or cats, and then to humans.

DVM: You've been quoted as saying you realized back then that surgical oncology for pets needed standardization. What did you mean?

Withrow: In veterinary schools in the 1970s, there was a perception that cancer in animals was untreatable. Back then we rarely used aggressive surgery, radiation or meaningful chemotherapy on animal cancers. I helped develop the discipline of surgical veterinary oncology. We were able to change the paradigm from late detection and poor prognosis to early detection, aggressive interventions and better outcomes.

There also was a need to standardize surgical dosages, similar to how radiation and chemotherapy dosages are standardized. So we were able to help develop the standards of how to surgically treat different types of cancers at different stages. Oncologists began to understand that with these standards they could get extended survival rates, and we got more meaningful and predictive outcomes in an evidence-based fashion. Based on staging, anatomical site and species, we could be more accurate with both big and small interventions once we standardized the surgical dosing. Then we started publishing these techniques, indications and outcomes. We continue to "sell" this model to funding agencies and prove that animal models are relevant.

DVM: Tell us about the limb-sparing technique you developed to treat canine osteosarcoma. What inspired you? How has this been used in human cancer treatment?

Withrow: My specific interest is in bone cancer, osteosarcoma in particular. We see it a lot in dogs, but it's more rare in children. We were able to help develop ways for both animals and kids to keep their limbs. A lot of our early work was with allografts and intra-arterial chemotherapy. Eventually, we were able to prove the safety and efficacy of our limb-sparing practices. We did this work parallel to our physician counterparts and were able to make contributions along the way. Now most kids and some dogs will have their limbs spared.