Cats could hold the key to understanding breast cancer

Scientists discovered the genetic changes that drive cancer formation in cats are similar to those seen in humans

Household cats could help us understand how breast cancer develops in humans.

That’s according to the first study of multiple cancer types in cats that has identified genetic changes that could help treat the condition in humans and animals.

Almost a quarter of all UK households own at least one cat. Cancer is one of the leading causes of illness and death in cats, however very little is known about how this develops.

Scientists at the Wellcome Sanger Institute, the Ontario Veterinary College in Canada, the University of Bern, analysed tumours from almost 500 pet cats from five countries.

They discovered the genetic changes that drive cancer formation in cats are similar to those seen in humans.

Scientists discovered the genetic changes that drive cancer formation in cats are similar to those seen in humans. (Victoria Hatch)

Bailey Francis, co-first author at the Wellcome Sanger Institute, said: “By comparing cancer genomics across different species, we gain a greater understanding of what causes cancer. One of our major findings was that the genetic changes in cat cancer are similar to some that are seen in humans and dogs.

“This could help experts in the veterinary field as well as those studying cancer in humans, showing that when knowledge and data flows between different disciplines, we can all benefit.”

Cats are exposed to some of the same environmental cancer risks as their owners, which means that some causes of cancer could, at least in part, be shared.

By sequencing DNA from tissue samples that had already been collected by the vet for diagnostic purposes, the study published in the journal Science, found certain genetic changes commonly found in cat cancers mirror those seen in human cancers. For example, they found similarities between feline mammary cancers and human breast cancers.

Researchers looked for around 1,000 human cancer-associated genes in both tumours and healthy tissue samples. This included 13 different types of cat cancer and allowed them to compare the genetic changes to those seen in human and dog cancers.

One cancer studied was mammary carcinomas - a common and aggressive type of cancer in cats. Researchers identified seven driver genes that led to the development of cancer when mutated.

The most common driver gene of this type of cancer was FBXW7, which is also found in 50 per cent of the cat tumours. In humans, changes in the FBXW7 gene in breast cancer tumours are associated with a worse prognosis - which is similar to what is seen in cats.

Certain chemotherapy drugs were found to be more effective in the cat mammary tumours with changes in the FBXW7 gene. Although further research is needed, these findings may mean it is possible to develop a therapy for both cats with mammary carcinoma and human breast cancer patients.

The second most common driver gene was PIK3CA, seen in 47 per cent of cat mammary carcinoma tumours. This is also a genetic change found in human breast cancer. But similarities in these driver genes were also seen across blood, bone, lung, skin, gastro-intestinal, and central nervous system tumours.

Researchers say these findings could also lead to new therapies for cancers across the two species.

Professor Geoffrey Wood, co-senior author at the Ontario Veterinary College, Canada, said: “Despite domestic cats being common pets, there was very little known about the genetics of cancer in these animals, until now.

“Our household pets share the same spaces as us, meaning that they are also exposed to the same environmental factors that we are. This 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.”