Cancer's assault on humans and pets is well known. But how often does the disease prey on animals in the wild? Nobody knows for sure, but the evidence of trouble is growing.

In a broad review of the literature, a team from the Wildlife Conservation Society suggests cancer risks should be considered, in addition to the more common concerns like habitat loss, in conservation efforts for wild animals.

“Most people probably don’t recognize how similar animals are to humans, that they are affected by the same processes,” says Denise McAloose, the chief pathologist at the Wildlife Conservation Society and lead author of the paper published today in Nature Reviews Cancer. “We have much to learn about wildlife diseases, their impacts on populations, and how all that is connected to the health of people and the planet.”
Certain species are at especially high risk. The Tasmanian devil, for example, suffers from a contagious facial tumor that is spreading rapidly and putting the largest carnivorous marsupial at risk of extinction. The species has “very significant impacts for populations and ecosystems in general,” McAloose tells “If lost, who knows what will happen next? There could be an explosion of rodents.” Conservationists are attempting to save the species through captive breeding.

While the Tasmanian devil’s cancer is not likely linked to human activity, other wildlife cancers could be. “Toxins in the environment can cause cancer in wildlife, not just in humans,” says McAloose, pointing to the higher prevalence her team found of cancers in sea turtles and beluga whales in polluted waters. She notes that while viruses may be the ultimate cause, the environment is likely to be “promoting or contributing to the occurrence of these tumors.”

Improved wildlife monitoring could also help people. “Animals act as sentinels,” she says. “From them, we might get a clue whether there’s something in the environment we need to look at… Then we could provide mitigation that would improve the health of both animals and humans.”

Picture of Tasmanian devil by Richard Fisher via Flickr.