Larger Animals Face Surprisingly Elevated Cancer Risks, Research Shows
18 March 2025 · Uncategorized ·
Source: · https://technews.tw/2025/03/17/bigger-animals-get-more-cancer-defying-decades-old-belief/
The scientific community has long believed that animal size is unrelated to cancer risk, a concept known as Peto’s paradox. However, recent research suggests this may not be the case, indicating larger animals are indeed more prone to developing cancer and potentially overturning this established understanding.
The study reveals that large mammals like elephants, giraffes, and pythons exhibit higher rates of cancer compared to smaller species such as mice, bats, or frogs. The findings were published in *Proceedings of the National Academy of Sciences* on February 24.
Peto’s Paradox is named after Richard Peto from Oxford University, who observed in 1977 that elephants—despite having trillions more cells than humans and mice—do not exhibit a higher incidence of cancer. This observation contradicted intuition and prompted scientists to propose anti-cancer mechanisms unique to large animals as explanations for the paradox.
Researchers at Reading University, UCL (University College London), and Johns Hopkins School of Medicine analyzed data from over 260 species and found that larger animals generally have a greater tumor rate—whether benign or malignant. They employed advanced statistical models to analyze cancer incidence rates across different species in relation to their size. The results demonstrate that regardless of whether they are mammals, birds, amphibians, or reptiles, the risk of developing cancer tends to increase with body size.
However, animals evolving rapidly into larger sizes often possess stronger anti-cancer mechanisms; for example, elephants have multiple copies of the tumor suppressor gene TP53. This effectively triggers apoptosis—programmed cell death—when cells are damaged, preventing them from becoming malignant.
The robust anticancer mechanism in elephants is reflected by their cancer risk being comparable to that of a tiger despite having significantly more cells. Dr. Joanna Baker at UCL explained: “As species evolve into larger sizes, they should develop stronger anti-cancer mechanisms as well. For example, elephants have unique abilities that reduce the threat from cancers even though they are large.”
The study also identified some notable exceptions to this general trend in cancer rates. Pet birds like cockatoos—weighing less than 30 grams—have a forty times higher incidence of cancer than expected. Conversely, naked mole rats, rodents known for their near immunity to cancer due to factors including high molecular weight hyaluronic acid that inhibits excessive cell proliferation, genetic stability, strong antioxidant capacity and low metabolic rate, represent an outlier.
Despite the new findings suggesting larger animals are more prone to developing cancers, their inherent anti-cancer mechanisms offer valuable insights. Dr. George Butler from UCL and Johns Hopkins University stated: “Animals naturally better at fighting cancer can provide fresh inspiration for cancer research. We could learn even more about how cancer forms and develop entirely novel treatment strategies.”
Future studies focusing on species with exceptional anticancer abilities may lead to revolutionary breakthroughs in the prevention and treatment of cancers.
(Image source: Freepik)
The study reveals that large mammals like elephants, giraffes, and pythons exhibit higher rates of cancer compared to smaller species such as mice, bats, or frogs. The findings were published in *Proceedings of the National Academy of Sciences* on February 24.
Peto’s Paradox is named after Richard Peto from Oxford University, who observed in 1977 that elephants—despite having trillions more cells than humans and mice—do not exhibit a higher incidence of cancer. This observation contradicted intuition and prompted scientists to propose anti-cancer mechanisms unique to large animals as explanations for the paradox.
Researchers at Reading University, UCL (University College London), and Johns Hopkins School of Medicine analyzed data from over 260 species and found that larger animals generally have a greater tumor rate—whether benign or malignant. They employed advanced statistical models to analyze cancer incidence rates across different species in relation to their size. The results demonstrate that regardless of whether they are mammals, birds, amphibians, or reptiles, the risk of developing cancer tends to increase with body size.
However, animals evolving rapidly into larger sizes often possess stronger anti-cancer mechanisms; for example, elephants have multiple copies of the tumor suppressor gene TP53. This effectively triggers apoptosis—programmed cell death—when cells are damaged, preventing them from becoming malignant.
The robust anticancer mechanism in elephants is reflected by their cancer risk being comparable to that of a tiger despite having significantly more cells. Dr. Joanna Baker at UCL explained: “As species evolve into larger sizes, they should develop stronger anti-cancer mechanisms as well. For example, elephants have unique abilities that reduce the threat from cancers even though they are large.”
The study also identified some notable exceptions to this general trend in cancer rates. Pet birds like cockatoos—weighing less than 30 grams—have a forty times higher incidence of cancer than expected. Conversely, naked mole rats, rodents known for their near immunity to cancer due to factors including high molecular weight hyaluronic acid that inhibits excessive cell proliferation, genetic stability, strong antioxidant capacity and low metabolic rate, represent an outlier.
Despite the new findings suggesting larger animals are more prone to developing cancers, their inherent anti-cancer mechanisms offer valuable insights. Dr. George Butler from UCL and Johns Hopkins University stated: “Animals naturally better at fighting cancer can provide fresh inspiration for cancer research. We could learn even more about how cancer forms and develop entirely novel treatment strategies.”
Future studies focusing on species with exceptional anticancer abilities may lead to revolutionary breakthroughs in the prevention and treatment of cancers.
(Image source: Freepik)