1- History of cancer
Although the risk of cancer increases as a person ages and gains weight, whales, the world's largest mammals, do not suffer from this threat. In fact, they are among the least susceptible animals to cancer!
In essence, cancer begins when cells transform abnormally and begin to grow and divide uncontrollably, in a way that disrupts the normal functioning of their biological environment.
According to the World Health Organization, cancer is the second leading cause of death globally, affecting millions of people of all ages worldwide.
Researchers believe that the spread of this disease and malignant tumors is mainly due to the spread of pollution and other environmental changes caused by man. However, many studies show that people have suffered from the insidious disease for thousands of years.
The first case of cancer that researchers have been able to document so far occurred in the first human ancestor, whose remains date back 1.7 million years. Finding these remains in a cave in South Africa, investigators have found evidence of osteosarcoma, an aggressive type of bone cancer, at the dawn of the human race.
However, humans are not the only mammals affected by cancer throughout history. The malignant tumor was the leading cause of death for cats, dogs, and some reptiles, birds, and fish.
Moreover, according to recent discoveries, even dinosaurs were not spared from this disease!
2- Do age and weight increase the risk of cancer
Experts explain that a person's age and weight can increase the risk of developing cancer. This makes sense because the longer a person lives, the more time there is for cells to mutate, and because, as the body ages, its cells may be more susceptible to mutations.
Also, the more a person weighs, and some scientists even suggest, the taller they are, the more cells that can undergo the mutation.
However, these associations do not apply equally across species in the animal kingdom. In fact, some animals, despite being very large and long-lived, are very unlikely to develop cancer.
Elephants, porpoises, and whales have incredibly low rates of cancer. Researchers have wondered why and what makes these animals resistant to malignant cell mutations in hopes of benefiting research to improve anti-cancer treatments for humans.
For elephants, a recent study found the answer to their immunity to malignant tumors. It also turns out that large snakes have tumor-suppressing genes that allow their bodies to stop a malignant tumor from forming.
Humans also have this gene. However, they only have one copy of it, while the number of elephants reaches 20 copies.
So what about whales?
3- Whales are immune to cancer!
A team of researchers from Northern Arizona University, in Flagstaff, Arizona State University, in Tempe, and other collaborating institutions think the answer may lie, again, in the genes of these aquatic mammals.
In the study — the results of which appear in the journal Molecular Biology and Evolution — researchers obtained permission to analyze a skin sample from Salt, an adult female humpback whale (Megaptera novaeangliae).
The female Salt Whale has been followed since the mid-1970s, so she had a long history of data and information available to the research team.
The team ran an RNA-sequencing test on the skin sample in order to compile a map of the whale's genome. Once this was done, the results were compared with the genetic information available from other types of whales, such as the blue whale, the bowhead whale, and the sperm whale.
The analysis revealed that some loci in the whales' genome have evolved at a faster rate than in other mammals. Specifically, these genes contained genes regulating the cell cycle, reproduction, and the DNA repair process inside the cell—essentially, the process for maintaining healthy cells.
Experts have noticed that genes involved in the process of preserving cells develop in human cancers.
It was also noted that the whale genome has many multiples of tumor suppressor genes, which prevent tumor development and growth.
This means that are immune to malignant tumors thanks to the genes they possess. This information can be of fundamental help in anti-tumor research in humans, and its use in human anti-cancer therapies.