Species that evolved rapidly in body size - such as the Greater Kudu and Big Horn Sheep - have fewer cancerous tumours, but the same is not true for non-cancerous tumours, according to new research.
The findings, provided from a study by scientists at University College London and the University of Reading, suggest evolution built stronger cancer defences in animals whose bodies were changing quickly. Non-cancerous (benign) tumours faced little evolutionary pressure to be controlled.
Published this week in the journal PNAS, the research builds on a previous study that found larger species like elephants have higher cancer rates than smaller ones like mice. While the new findings confirm that body size itself increases tumour prevalence, they reveal that species evolving rapidly in body size have fewer cancerous tumours.
Professor Chris Venditti, senior author of the research at the University of Reading, said: "Cancer is as much an ecological and evolutionary challenge as it is a medical one. By examining how tumours emerge and persist across species, we have gained insight into the fundamental biology of cancer. Cancer is not just a failure of cells, but a reflection of the evolutionary pressures that shaped them.
"The findings provide insight into how cancer resistance mechanisms have evolved across different animal groups. Understanding these evolutionary patterns could inform research into human cancer biology and treatment resistance."
Birds show there are some drawbacks to rapid evolution
The research team found differences between the cancer rates of the 77 birds and 87 mammals they studied. In birds, lineages that gave rise to new species more quickly had a higher prevalence of both tumour types, possibly because birds have a smaller, more compact genome relative to mammals potentially making them more vulnerable to tumour-promoting genetics changes.
Dr George Butler, lead author of the research at University College London and Johns Hopkins said: "Our findings show that not all tumours are equal. Evolution etches fingerprints even on diseases like cancer. The fact that malignant tumours decline with faster body size evolution suggests that adaptation can help evade cancer in rapidly changing species. When species get big quickly, they seem to 'pick up' better anti-cancer mechanisms along the way. Specifically, our findings suggest that these defensive mechanisms are cancer unique and not applicable to growths as a whole.
"Shuffling genetic information creates new species, but it can also cause problems. In human prostate cancer, for example, two genes fusing together drives more aggressive disease. Our findings suggest birds are particularly vulnerable to these genetic mix-ups because their compact genomes leave little room for mistakes."
