Big animals face heightened cancer risk, yet enhanced defenses have emerged

Larger animals live longer and have more cells, and are expected to be at a higher risk of developing cancer. A comprehensive analysis of 263 species suggests that this is true, but also finds that some large animals have evolved ways of reducing risk.

“We provide the first empirical evidence that there is a link between body size and cancer prevalence, meaning that larger species increase cancer than smaller species. “I say it. George Butler University College London.

The results are in contrast to previous studies found. There is no link between weight and cancer rate. But many of these were related to just a few dozen species, Butler says.

To gain a broader view, Butler and his colleagues analyzed data on the size and cancer rates of 79 bird species, 90 mammal species, 63 reptiles and 31 amphibians. The data comes from previous studies by other researchers who sifted through autopsy records that record whether a breeding animal stored in a place like Zoos or an aquarium had cancer when it died. .

The team found that smaller animals were slightly more likely to have cancer than fewer animals at the time of death. Each 1% increase in body weight was associated with an average increase of 0.1% in cancer rates between birds and mammals. Because body mass data were not available in reptiles and amphibians, the team used body length and found that it was associated with an average increase in cancer rate of 0.003% for every 1% increase.

Butler and his team say their discoveries will challenge a long-standing idea known as the Pete Paradox. on the other hand, Veragolbunova At the University of Rochester in New York, the weak correlation still needs explanation.

“The increased risk they see is very, very minor and not proportional to their body size,” she says. “If you take small animals like mice and humans are 100 times larger, or elephants are 100 times larger, the difference in cancer rates is not 100 times higher in humans and 1000 times higher in elephants.”

It suggests that larger species have evolved more ways to protect themselves, Golbunova says.

Indeed, by using evolutionary trees to infer evolutionary rates of animal body size, the team said that if the size increases more rapidly during evolution, birds and mammal species of similar sizes can be We found it to provide better protection against cancer.

Previous studies have identified genetic adaptations in elephants and whales, protecting against cancer by improving DNA repair and preventing broken cells from dividing.

A deeper understanding of how some animals resist cancer can lead to new treatments for people, says Golbunova. “In these cancer-resistant animals, there are specific biological pathways of different fine-tuning, for example, targeting these pathways and then killing cancer cells more efficiently, or perhaps killing cancer cells. You can even prevent cancer from occurring,” she says.

“As these mechanisms have been tested over millions of years in the course of evolution, they are likely to become highly promising drugs,” she says.