In a large-scale international study published in Science, researchers analyzed the genes involved in cat cancer on a scale never attempted before. The findings could improve cancer treatment in cats while helping scientists understand how some cancers develop in humans and other animals.

The researchers also created a freely available resource that scientists can use to study the genetics of cancer in cats.

Cancer is one of the leading causes of illness and death in cats. However, scientists have historically known far less about the genetic changes behind feline tumors than they do about cancers in humans and dogs.

Dr. Jeffrey Wood, professor of pathobiology at the University of Guelph and co-senior author of the study, said that gap is beginning to close.

“Despite domestic cats being common pets, until now little was known about the genetics of cancer in these animals,” Wood said.

Cat and human cancers share important genetic changes

Researchers examined tumor samples from about 500 domestic cats in five countries. They searched for mutations and other genetic changes that help cancer form and grow.

Many cancers are caused by changes in genes that control cell growth, division, DNA repair, or cell death. When these genes are altered, cells can begin growing uncontrollably. Scientists often refer to genes that directly contribute to tumor growth as cancer driver genes.

The research team found that many cancer driver genes involved in feline cancer are also well known in human and dog cancers.

One notable example involves aggressive breast cancers that develop in mammary tissue. The most common driver gene found in the cat mammary tumors studied was FBXW7. Mutations in this gene appeared in more than 50 percent of the tumors tested.

FBXW7 normally helps regulate proteins involved in cell growth and division. When the gene is damaged, some growth-promoting proteins can accumulate, helping cancer cells survive and spread.

In humans, FBXW7 mutations in breast cancer are associated with a poor prognosis, similar to changes observed in cats.

Researchers also identified similarities between feline cancers and human cancers affecting the blood, bones, lungs, skin, gastrointestinal system, and central nervous system.

Shared environments may provide clues about cancer risk

The genetic similarities may be especially useful because domestic cats often live in the same environments as humans.

Cats can encounter many of the same environmental factors as their owners, including household chemicals, air pollutants, smoke, and other exposures that may affect cancer risk. Studying naturally occurring cancers in pets could therefore help researchers understand how genetics and the environment interact.

“This study will help us better understand why cancer develops in cats and humans, how our environment affects cancer risk, and perhaps help us find new ways to prevent and treat cancer,” Wood said.

Genetic findings could guide feline cancer treatment

The findings may also influence cancer treatment. Researchers found that certain chemotherapy drugs were more effective against mammary tumors in cats with a mutated FBXW7 gene.

That result was observed only in tissue samples. It has not yet been shown whether the same approach would be effective in living cats or humans. Still, the discovery suggests that genetic information could eventually help veterinarians and doctors identify more effective treatments for specific tumors.

This approach is known as precision oncology. Instead of treating every cancer of the same type in exactly the same way, precision oncology uses the molecular and genetic characteristics of an individual tumor to guide treatment.

Co-senior author Dr. Sven Rottenberg of the University of Bern said the study’s large collection of donated tissues made it possible to compare drug responses across tumor types.

“Having access to such a large set of donated tissues allowed us to assess drug responses across tumor types, something that has not been possible before at this scale,” Rottenberg said.

Co-lead author Bailey Francis of the Wellcome Sanger Institute said the findings could also have implications for dogs.

“We all benefit when knowledge and data flow between different disciplines.”

How cat cancer research could help pets and people

The project brought together researchers from the Wellcome Sanger Institute, the University of Guelph’s Ontario Veterinary College, the University of Bern, and other institutions.

Rather than collecting all-new samples, the research team sequenced DNA from tissue that veterinarians had already obtained for diagnostic purposes.

This allowed scientists to study naturally occurring cancers in large numbers of cats and compare genetic patterns across different tumor types.

The findings also support a broader research strategy known as One Medicine. This approach emphasizes that human and veterinary medicine can inform each other.

Cancer treatments developed for humans may be evaluated in cats with naturally occurring tumors, while discoveries from feline cancer research and clinical trials may help shape future human studies.

This two-way interaction is especially valuable because pets naturally develop many of the same diseases as humans while sharing many aspects of the same environment.

Researchers hope the new genetic database will eventually help bring more personalized cancer treatments to cats.

Senior author Dr. Louise van der Weyden of the Wellcome Sanger Institute said the study provides a foundation for the next stage of feline cancer research.

“We can now take the next step towards feline precision oncology and keep up with the diagnostic and treatment options available for dogs with cancer, and ultimately for humans.”

This research was funded in part by the EveryCat Health Foundation, CVS Group, Wellcome, the Natural Sciences and Engineering Research Council of Canada, and the Swiss National Science Foundation.