Cancer is much less common in elephants than in humans, even though the big beasts' bodies have many more cells. That's a paradox known among scientists, and now researchers think they may have an explanation.
Compared with just one copy in humans, elephants' cells contain 20 copies of a major cancer-suppressing gene, two teams of scientists report.
The findings aren't proof that those extra p53 genes make elephants cancer-resistant, but if future research confirms it, scientists could try to develop drugs for humans that would mimic the effect.
Dr. Joshua Schiffman, a pediatric cancer specialist at the University of Utah who led one of the teams, began his research after hearing a lecture a few years ago about Peto's paradox—that large animals have comparatively lower cancer rates than smaller species.
The lecturer mentioned that elephants seemed to have extra copies of the p53 gene. Schiffman's patients include children with incomplete p53 genes because of a condition called Li-Fraumeni syndrome, which greatly increases their chances of developing cancer.
His team—as well as a second group of scientists—pinned down the size of the elephants' surplus genes—20 copies.
Schiffman and his colleagues compared how elephant cells reacted to radiation, compared with cells from 10 healthy humans and 10 patients with Li-Fraumeni syndrome.
The elephant cells self-destructed at twice the rate of healthy human cells and more than five times the rate of cells from patients with the syndrome. Cells that don't self-repair or self-destruct when exposed to carcinogens become prone to developing cancer. The scientists' work was published in JAMA.
While the research won't lead to any immediate treatment for humans, progress against cancer can come “from unexpected directions,” said Dr. Ted Gansler of the American Cancer Society.