Cancer: Why Elephants Have an Enhanced Resistance

Elephants have a strong internal defense system that ultimately enhances the animal's resistance to cancer, a new study revealed. Researchers from the University of Utah Health Sciences took a closer look at elephant genetics to better understand how their defense system compares to that of a human.

"Nature has already figured out how to prevent cancer. It's up to us to learn how different animals tackle the problem so we can adapt those strategies to prevent cancer in people," Joshua Schiffman, a co-senior author of the study and a pediatric oncologist at Huntsman Cancer Institute, University of Utah School of Medicine and Primary Children's Hospital, said in a news release.

Compared to humans who have only two, scientists discovered that elephants have 38 additional modified copies (alleles) of a gene that encodes p53, which is a well-defined tumor suppressor. Elephants also have a more efficient way of killing damaged cells that may otherwise become cancerous.

Ultimately, less p53 means that one's body doesn't jump into damage-response mode quick enough to kill cancerous cells. Patients with Li-Fraumeni Syndrome, for example, have only one active copy of p53 and have a 90 percent lifetime risk of getting cancer. This suggests that extra p53 is responsible for elephants' enhanced resistance to cancer, the researchers noted.

Scientists have long debated why elephants rarely get cancer. As Schiffman notes in his study, elephants have 100 times as many cells as humans, therefore they should be 100 times more likely to develop cancerous cells. Yet, this study confirms that elephants have a stronger defense against the disease and are diagnosed with cancer far less often than humans.

"By all logical reasoning, elephants should be developing a tremendous amount of cancer, and in fact, should be extinct by now due to such a high risk for cancer," Schiffman said in a statement. "We think that making more p53 is nature's way of keeping this species alive."

Their study, recently published in the Journal of the American Medical Association (JAMA), sheds light on how animals have valuable information that scientists could use to find cures for many human illnesses.

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