OVC Prof. Stefan Keller specializes in lymphoma testing.

When a veterinarian suspects cancer in an animal, the usual process to make a definite diagnosis is to take a tissue sample (a biopsy) and have it examined by a pathologist under a microscope. But one type of cancer — lymphoma — is harder to identify.

Prof. Stefan Keller, who joined the Ontario Veterinary College’s Pathobiology Department earlier this year explains: “Lymphoma arises from lymphocytes, which are immune cells that can appear anywhere in the body to fight microorganisms. When you see a bunch of these cells under the microscope, it is sometimes impossible to tell if they are ‘good guys’ that are on a defense mission or if they are ‘bad guys’ — cancer cells that are out of control. Distinguishing inflammation from cancer is obviously crucial for diagnosis, treatment and prognosis. We don’t want to put a patient with an infection on multi-agent chemotherapy. Giving a lymphoma patient antibiotics and waiting is not the best choice either.”

Keller’s research is looking for ways to diagnose lymphoma based on genetics. In general, all cells in an individual have the same genetic code. Lymphocytes, however, have changes in one specific gene to enable them to bind bacteria or other microorganisms. This gene is different in each lymphocyte to allow recognition of a large number of different microbes. When lymphocytes are gathered to respond to an infection, they differ genetically, even though they might look identical under the microscope.

On the other hand, cancer is the result of a single cell reproducing itself repeatedly, which means that all daughter cells are genetically identical. Cancer and infection can hence be distinguished by the genetic diversity of lymphocytes in a given sample.

“Developing a reliable test, however, depends on knowing the entire gene sequence,” says Keller. While the idea has been around in veterinary medicine since 1999, the full genomes for dogs, cats and horses have only been completely described in recent years. The older tests — without the full genomes — had a high false-negative rate (meaning cancer was present but the test said it was not). Keller’s research is looking at updating and improving these tests, and making them available for animals of other species.

“If we can recognize and confirm cancer quickly, we can initiate correct treatment right away and increase the patient’s chances of survival,” says Keller.

A native of Germany, Keller began his veterinary studies at the University of Berlin. He then completed specialized training in pathology in Zurich, Switzerland, before heading to the University of California, Davis, to obtain his PhD and training in immunopathology. When he’s not studying cancer cells, Keller enjoys running, rock climbing, skiing and other outdoor activities, and spending time with his 18-month-old son.

He chose to come to U of G because he likes the more comprehensive role of veterinary pathologists, allowing him to engage in teaching, research and diagnostics.

“My research is very applied, and being involved in diagnostics is essential to identify problems and to tailor solutions more precisely,” he says. “Genetic testing does not replace a microscope — combining both is the key.

Keller also likes the teamwork and support at the college, which he experienced upon arrival: faculty members helped him find housing in town and loaned him the essentials, such as a coffeemaker, until his household goods arrived from California.