Curiosity Killed the Cat—And Might Save the Human

Cats and humans last shared an ancestor about 90 million years ago. 90 million years seems like enough time for two species to end up with nothing in common—different bodies, different lifespans, different diets, different everything. While you both live in the same apartment, breathe the same air, and lose interest when the second food disappears, the list of things you have in common with your cat is pretty short. You’d think cancer would be one thing that sets you apart. In fact, cancer presents differently in almost every species, which is why a drug that can wipe out a tumor in a mouse can do nothing in a human. But according to a study published in February 2026, the very cat that shares your home shares your cancer too.

That study, led by a team at the Wellcome Sanger Institute in the UK, sequenced the DNA of tumors from 493 domestic cats. Sequencing, or decoding a cell’s DNA to find the mutation that turned it from healthy to malignant, was done across 13 different tumor types, focusing on the feline version of approximately 1,000 genes known to cause cancer in humans. This was the first-ever large-scale genetic map of feline cancer; previously, the field only relied on small studies. The team didn’t even need to conduct experiments on living animals; they used samples that veterinarians collected across five countries for routine diagnostic work. What they revealed in these samples was a genome that looked unsettlingly familiar.

Not every mutation in a tumor actually drives the tumor’s development. In other words, many mutations are harmless. A few, though, do the real damage. These genes, called driver genes, actively push a cell towards cancer. In these cats, the team found 31 of these driver genes—and the closer the scientists looked at these genes, the stranger the resemblance got. 

TP53, one of the most well-known tumor-suppressor genes in human cancer and the most mutated gene in the feline genome in the study, was altered in approximately 33 percent of all feline tumors. In humans, TP53 is mutated at almost exactly the same rate, around 34 percent. TP53 is the cell’s emergency brake: when a cell’s DNA gets damaged, TP53 halts division until the repair is done, or forces the cell to self-destruct if it can’t be fixed. When mutated, the broken cells are free to keep dividing, which is why it sits at the center of so many cancers. Examining another driver gene, PTEN, the team found that it was lost in about 20 percent of the cat tumors, closely mirroring the 25 percent in humans.

The similarity between the genomes didn’t just stop at having similar percentages of showing up. FBXW7, the most mutated gene in feline mammary cancer, or the cat version of breast cancer, is linked to more aggressive tumors and lower survival rates in both human and feline cancers. Not only do these genes mutate at similar rates, but they also lead to the same effect. The overlap ran through nearly every cancer the team looked at, from skin and bone to blood, lung, and brain. Genes aren't the only thing cats share with us.

What makes this similarity even more valuable is that cats also share our environment. A household cat breathes the same air as you, sleeps on the same furniture, and tracks through the same dust, meaning that it’s exposed to many of the same elements that turn a healthy cell cancerous: secondhand smoke, chemicals shedding off furniture, fumes from cleaning products. Put that shared environment alongside the shared genes, and a pet cat becomes something no lab animal can be. It gets cancer the way we do. 

This is the part that has researchers excited. For decades, cancer studies have been reliant on lab mice whose tumors are triggered deliberately, using chemicals or gene engineering, in sterile environments that don’t resemble the world we live in. It’s part of the reason why a drug that may work on a mouse tumor often doesn’t work on a human one. A pet cat mirrors our environment, avoiding the problem that lab mice have. As one of the study’s authors explained, the future of treatment is targeting the exact mutation driving a tumor, not just treating “a cat” or “a human.” Hence, the shared mutations indicate that a drug that works in one may be a real lead for the other. 

This idea is already being tested. The team found that feline mammary tumors with a mutated FBXW7 gene responded to vincristine, a chemotherapy drug already used for human treatment. This is a concrete step toward matching treatment to a cat’s specific mutation instead of giving every cat the same generic chemotherapy. Cancer is among the leading killers of pet cats, and their care has trailed years behind what dogs and humans receive.

For humans, the payoff is different. A cat’s cancer resembles ours, but develops in a fraction of the time, so a new drug could be tried in pet cats before it ever reaches a person. We have spent decades building artificial cancers in mice to understand our own. The whole time, a better answer was sitting on the windowsill. Curiosity killed the cat, as the saying goes, but the cat may be about to return the favor by helping us cure ourselves.