FBXW7, a gene that normally helps regulate proteins involved in cell growth, is mutated in more than half of the mammary tumors in domestic cats, and the same gene is altered in human breast cancers that carry a worse prognosis. The count comes from a genetic survey led by the Wellcome Sanger Institute in Cambridge, England, with the University of Guelph’s Ontario Veterinary College and the University of Bern.
Dr. Louise van der Weyden of the Sanger Institute is the senior author, and Dr. Geoffrey Wood of Guelph and Dr. Sven Rottenberg of Bern are co-senior authors. The paper appeared in Science on February 19, 2026, under DOI 10.1126/science.ady6651.
A survey of nearly 500 cats in five countries
According to the Wellcome Sanger Institute’s release, the team analyzed tumors from about 500 pet cats across five countries, covering 13 different cancer types. A Cornell University College of Veterinary Medicine account puts the number at 493 tumor samples. The screen targeted roughly 1,000 genes already tied to human cancer, with healthy tissue from the same animals used for comparison.
Mammary carcinoma, the cat equivalent of breast cancer, yielded seven driver genes. FBXW7 led the list at more than 50 percent of feline mammary tumors, followed by PIK3CA at 47 percent. The institutions’ releases give those shares but not the number of mammary cases behind them, so the denominator is the mammary carcinoma subset of the cohort, not all 493 samples, and the exact count of cases is not stated.
FBXW7 and the human comparison
The University of Guelph release describes FBXW7 as the most common driver gene in feline mammary cancer. Its normal job is to regulate proteins involved in cell growth; when it is mutated, growth-promoting proteins accumulate. In people, the release says, FBXW7 mutations in breast cancer correlate with worse prognosis, which is the parallel behind the description of mirroring aggressive human breast cancer.
The Cornell account words it the same way, saying FBXW7 mutations in humans are typically linked to a worse prognosis in breast cancers. Neither release names a specific human subtype, so the human half of the comparison rests on the prognosis link and not on a count of human tumors.
Wood, a professor of pathobiology at Guelph, said that despite domestic cats being common pets, “there was very little known about the genetics of cancer in these animals, until now.” He also pointed out that pets share their owners’ environments, which makes them a useful comparison for shared cancer risk factors.
The wording of the share matters. The Sanger, Guelph, Cornell and EurekAlert releases all say “more than half” or “over 50 percent,” so “half” in the sense of a round majority is the most that can be stated; none gives a figure such as 52 or 58 percent. PIK3CA, the second gene on the mammary list at 47 percent, is also a recurrent breast cancer gene in people, which the Sanger release counts among the mutations that mirror human patterns.
Other tumor types and drug testing
Mammary cancer was one slice of the survey. The Guelph release describes the work as the first large-scale genetic profiling of feline cancers, and the wider cohort also turned up genetic parallels with human tumors of the blood, bone, lung, skin, gastrointestinal tract and central nervous system. Those parallels are why the authors argue that cats, which share homes and environments with their owners, make a useful comparison population for cancer genetics.
The team also tested chemotherapy drugs on the samples. The Guelph and EurekAlert releases report that certain drugs were more effective against cat mammary tumors with the mutated FBXW7 gene, and the Cornell account specifies that the drug testing used laboratory tissue cultures, not treated animals. That distinction matters: the result is a signal about which cancers respond in a dish, not a treatment protocol for cats.
Van der Weyden described the work in the EurekAlert release as “one of the biggest ever developments in feline oncology,” arguing that the genetics of cat cancers are no longer unexplored territory. At Cornell, Dr. Latasha Ludwig, an assistant clinical professor, said veterinary oncology is moving toward a stage in which treatment targets the specific mutation, not just the species, and Dr. Bruce Kornreich, director of the Cornell Feline Health Center, noted that cats and humans suffer from many of the same diseases.
The funders were the EveryCat Health Foundation, CVS Group, Wellcome, Canada’s NSERC and the Swiss National Science Foundation, and the work is framed by its authors as a “One Medicine” approach in which findings travel in both directions between veterinary and human oncology.
The figure that remains unpublished in the institutions’ releases is the number of mammary carcinomas behind the 50 percent share.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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