The reason elephants don’t get cancer

Elephants very rarely get cancer, a long known fact now attributed to the pachyderm’s 20 modified copies of a gene us humans have just one of, the tumour suppressor gene, p53.

Joshua Schiffman, a paediatric oncologist at the University of Utah’s High Risk Paediatric Cancer Clinic and researcher at the Huntsman Cancer Institute, was first inspired to study how the natural world deals with cancer when his dog died. A Burmese Mountain dog, Schiffman learned his beloved pet had stood an amazingly increased risk of developing the sarcoma cancer that lead to his demise, causing him to question why some animals are more prone or resistant to cancer. 

Schiffman met Arizona State University’s Carlo Maley, a researcher curious about Peto’s Paradox—the idea that increased body size doesn’t increase the incidence of cancer though biologically speaking it should. The more times a cell divides, the more chances it has to mutate. Animals that divide more cells than others should statistically encounter cancer more often.

‘We’ve long known that elephants, like many very large animals, actually get cancer far less often—that’s the paradox,’ says Schiffman.

Maley and Schiffman decided to join forces to figure out the pachyderm’s secret, and when Schiffman learned the staff at the Utah Hogle Zoo drew blood from their African elephant’s weekly to monitor health, filed with the zoo’s ethical committee and gained samples.

A year later, Schiffman got a call from Ringling Bros. Center for Elephant Conservation, saying they didn’t just have an interest in pursuing the p53 work—offering him access to fresh specimens—but would help fund it as well. With a 20-year commitment to the research of elephants, the centre boasts one of the largest Asian elephant herds in the Western Hemisphere.

First the team scoured through the necropsy data of 36 different species to put elephant’s cancer-resistance into perspective, finding the big, long lived animals had cancer rates a little lower than five percent, compared to the human norm of between 11 to 25 percent.

Photo by JONATHAN PLEDGER / Shutterstock
Photo by JONATHAN PLEDGER / Shutterstock

‘Elephants had 40 alleles encoding for p53, the tumour suppressor gene—us humans have just two—insinuating they’d evolved these modified copies to provide this amazing protection,’ Schiffman says. He explains the correlation was logical—p53, formally Tp53, either stops damaged cells from continuing to divide or initiates cell death. It’s also a gene commonly altered, or lacking, in genetically-prone cancer patients.

To figure out just how the p53 copies were whittling-out damaged cells so effectively the team then exposed blood from elephants, healthy humans, and some of Schiffman’s Li-Fraumeni syndrome (LFS) patients—people with only half the amount of normal p53, to radiation.

‘Elephant’s damaged cells were designated for death at higher rates,’ he says. ‘Nature knows that a repaired cell could go on to propagate, whereas a dead cell can’t.’

Publishing their work this month in the Journal of the American Medical Association, or JAMA, Schiffman warns they’re not toting a ‘cure’ by any means, but rather the possible answer to a long-time scientific curiosity with big implications for human health. The team will consider if a drug can be developed to mimic the elephant-effect, or whether human patients could be successfully infused with p53-enhanced pachyderm-fluids.

‘Nature usually already holds the solutions,’ says Schiffman. ‘Most other species have been working on these biological questions for much, much longer. Now we stand to benefit from the lessons they’ve learned.’

The Ringling Brothers have already committed 250,000 USD to the project—now they’ve signed on to provide another one million. Schiffman says to get involved, donate, or learn more about the project visit their funding page.