Cancer risk across mammals

Area of Science:

• Evolutionary Biology
• Cancer Research
• Zoology

Background:

• Cancer is common in animals, with theories predicting higher risk in larger, longer-lived species due to more cell divisions.
• Peto's paradox highlights the lack of correlation between body size/longevity and cancer risk across species.
• Empirical data on cancer risk in diverse, non-model species is scarce.

Purpose of the Study:

• To investigate Peto's paradox by analyzing cancer-related mortality across mammalian species.
• To determine the relationship between body size, lifespan, and cancer risk in mammals.
• To explore factors influencing cancer mortality across the mammalian tree of life.

Main Methods:

• Compiled a database of cancer-related mortality from 110,148 adult zoo mammals across 191 species.
• Mapped age-controlled cancer mortality onto the mammalian evolutionary tree.
• Analyzed correlations between cancer mortality, body mass, lifespan, diet, and phylogeny.

Main Results:

• Demonstrated the widespread occurrence of cancer in mammals with significant inter-order variation in mortality.
• Revealed that cancer mortality risk is largely independent of body mass and adult lifespan across species.
• Identified a higher cancer-related mortality in carnivorous mammals, particularly those consuming other mammals.

Conclusions:

• Provided unequivocal evidence supporting the body size and longevity components of Peto's paradox.
• Highlighted the crucial role of life-history evolution in developing natural cancer resistance.
• Advanced the understanding of natural anticancer defenses and their evolutionary drivers.