An international research team has sequenced the largest collection of cat tumors to date, and the results close a long-standing genetic blind spot in feline medicine: many of the same cancer driver genes found in humans and dogs also drive cancer in domestic cats.

The study, published in Science (Francis et al., 2026, 391:793), analyzed tumor tissue from nearly 500 domestic cats across five countries. Rather than collecting new samples, the researchers sequenced DNA from tissues veterinarians had already obtained for diagnostic purposes — a design that allowed them to study naturally occurring cancers at a scale never attempted in the species.

The collaboration brought together the Wellcome Sanger Institute, the University of Guelph's Ontario Veterinary College, the University of Bern and other institutions.

The headline number: FBXW7

The most consequential finding for companion-animal practice concerns mammary cancer. The most common driver gene in feline mammary tumors was FBXW7, mutated in more than 50 percent of tumors examined. FBXW7 normally regulates proteins involved in cell growth and division; when the gene is damaged, growth-promoting proteins can accumulate, helping cancer cells survive and spread.

The parallel with human oncology is direct. In human breast cancer, FBXW7 mutations are associated with worse prognosis — the same pattern now documented in cats.

The team identified shared driver genes between cat and human cancers across multiple systems: blood, bone, lung, skin, gastrointestinal tract and central nervous system.

What it could change at the exam table

The genetic data already carry a therapeutic signal. In tissue-sample experiments, certain chemotherapy drugs showed greater effectiveness against cat mammary tumors carrying the mutated FBXW7 gene. That is an in vitro result only — it does not establish that the same approach will work in living cats or in people. But it points toward what the researchers describe as precision feline oncology: using the molecular features of an individual tumor to guide drug selection rather than treating every tumor of a given type identically.

That model already exists in canine oncology, and the gap between diagnostic and therapeutic options for cats and dogs is one the study's senior authors explicitly want to close.

"We can now begin to take the next steps forwards towards precision feline oncology, to catch up with the diagnostic and therapeutic options that are available for dogs with cancer, and ultimately one day, humans," says Dr. Louise Van Der Weyden, senior author at the Wellcome Sanger Institute.

Dr. Sven Rottenberg, co-senior author at the University of Bern, notes the scale of the tissue resource itself was enabling: "Having access to such a large set of donated tissues allowed us to assess drug responses across tumor types, in a way that hasn't been possible at this scale before."

Dr. Geoffrey Wood, co-senior author and pathobiology professor at the University of Guelph, frames the study against the field's thin baseline: "Despite domestic cats being common pets, there was very little known about the genetics of cancer in these animals, until now."

Public-health dimension: shared environments

The comparative findings matter beyond the cat. Because domestic cats share their owners' environments — household chemicals, air pollutants, smoke and other exposures that may influence cancer risk — naturally occurring feline tumors offer researchers a way to study how genetics and environment interact in cancer development.

"This study can help us understand more about why cancer develops in cats and humans, how the world around us influences cancer risk, and possibly find new ways to prevent and treat it," Wood says.

The work supports a One Medicine strategy: cancer treatments developed for humans could be evaluated in cats with naturally occurring tumors, while feline study findings and clinical trials could inform human research. Co-first author Bailey Francis of the Wellcome Sanger Institute suggests the benefits extend to dogs as well: "When knowledge and data flows between different disciplines, we can all benefit."

An open resource

The researchers created a freely available database of feline cancer genetics that other scientists can use. Funding came from EveryCat Health Foundation, the CVS Group, Wellcome, the Natural Sciences and Engineering Research Council of Canada and the Swiss National Science Foundation.

Cancer remains one of the leading causes of illness and death in cats, and no precision diagnostic or therapy claims regulatory status yet — the drug-response findings are preliminary, tissue-level observations. Still, with the feline oncogenome mapped and an open dataset in hand, veterinary oncologists now have the substrate to develop the tumor-profiling workflows that canine and human medicine already use.