Cancer can occur in most animals, large or small. Therein lies an evolutionary conundrum: If all cells have a roughly equal chance of acquiring cancer-causing mutations, then big animals—which have more cells—should have a higher risk for developing malignancies. But that’s not the case. About one in four Americans will die of cancer, yet no more than one in 20 elephants suffers the same fate. Meanwhile, dogs are more than two and a half times more likely to develop cancer than humans are. 

Learning how different species evolved to be more or less vulnerable to cancer might lead to new strategies for preventing and treating the disease. University of Utah pediatric oncologist Joshua Schiffman became intrigued by this possibility after his dog Rhody died. The Bernese mountain dog suffered from histiocytic sarcoma, an aggressive cancer that afflicts about one in four members of this breed. In collaboration with North Carolina State professor of genomics Matthew Breen, Schiffman is comparing the genomes of dogs diagnosed with cancer with genetic data from human cancer patients in hopes of identifying markers that could lead to early diagnosis of diseases such as glioblastoma, an often-fatal brain malignancy.

On the other end of the size scale, Schiffman is studying elephant blood obtained from Utah’s Hogle Zoo and Ringling Bros. and Barnum & Bailey Circus, in hopes of identifying mechanisms that minimize the pachyderm’s cancer risk.