For many years, scientists have wondered why large animals like African elephants hardly ever get cancer.
They have 100 times as many cells as people, and if every living cell had an equal chance of becoming cancerous, elephants should then have a greater risk of developing cancer. But that rarely happens. Scientists now think they know why.
Their findings, published in the Journal of American Medical Association last week, may prove crucial in the fight against human cancer.
This study has also interested Kenya’s conservation community, who are fighting to keep elephants alive amid rampant poaching.
The scientists from the University of Utah and Arizona State University analysed a large database of African elephant deaths and found that only less than five per cent of elephants are killed by cancer, compared to 11 to 25 per cent of human beings.
This is strange considering the elephants’ size and their long life span of 50 to 70 years.
But in search of an explanation, they found that African elephants have extra copies of a gene that suppresses tumours. “The elephants have at least 40 copies of genes that code for p53, the protein well known for its cancer-inhibiting properties. Humans have only two,” says the study.
“We think that making more p53 is nature’s way of keeping this species alive,” says co-senior author Joshua Schiffman, a pediatric oncologist at the University of Utah School of Medicine.
African elephants also have a mechanism for killing damaged cells that may become cancerous. The findings could lead to new strategies for treating cancer in humans.
“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,” Schiffman said.
Kenyan wildlife experts welcomed the study but said despite proving elephants can save human life, the study is unlikely to stop the ongoing haemorrhage of African elephants.
“This discovery reveals that despite decades of research, we still know so little about elephants. Will [the study] save them? No,” says WildlifeDirect director Dr Paula Kahumbu, who led the highly successful Hands Off Our Elephants campaign urging the government to stop poaching.
Dr Kahumbu says the study is also unlikely to spur poaching, as it happens with rhinos who are hunted because their horn is wrongly rumoured to cure cancer and work as an aphrodisiac.
“Elephants are not part of the traditional medicines of Asia. Rhinos are. The traditional use of rhino parts to cure cancer, or vultures in Muti, and most traditional medicines has virtually nothing to do with any science. It’s all based on myth,” she says.
Last year, 164 elephants and 35 rhinos were poached in Kenya. The country lost 302 elephants and 59 rhinos in 2013. In 2012, 384 elephants and 30 rhinos were killed by poachers while in 2007, 47 elephants and five rhinos were killed.
Chief executive officer of Ol Pejeta conservancy Richard Vigne praises the report but said it will not affect poaching levels.
“Poaching of elephants is driven by the high prices payable for ivory driven by demand from the Far East. I doubt that will change with this piece of research which is unlikely to be widely disseminated. To stop poaching we need to curb demand for ivory – that is the bottom line,” he says.
Ian Douglas-Hamilton, the head of local conservation NGO Save The Elephants, notes that elephants risk being extinct.
“If this continues, Africa’s elephants could be gone from the wild within a generation,” he told the Star in an earlier interview.
According to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Cites), elephant poaching in Africa reached a peak in 2011 and has since stabilised, albeit at “unsustainably high levels”.
Why we don’t have a cure for cancer
1. There will never be a single cancer cure because cancer refers to a family of more than 100 different diseases characterised by abnormal cell growth.
2. Indeed, there are successful treatments. The greatest advancements have been in the area of childhood cancers. Childhood leukemia used to kill about 80 percent of kids with the disease. Today more than 80 percent survive.
3. Cures for the major killers, such as cancers of the lung, breast and liver, remain elusive primarily because of the unpredictable nature of cancer cells. When a normal cell divides, the cell’s DNA is copied more or less perfectly. But each division of a cancer cell brings about new changes in the DNA. So a drug might be able to kill some but not all of the cancer because each cell is a little different.
4. More disconcerting is the ability of a cancer stem cell to hide. Chemotherapy might effectively kill an entire tumor, but cancer stem cells might evade the drugs and cause a relapse of the cancer years later.
5. Another problem is the lack of good animal models. Treatments rarely work well in humans because, among many issues, it is difficult to gauge the possibility of relapse years later when a mouse only lives two years.
– From Livescience