World's Oldest Surviving Cancer Originated in a Dog that Lived 11000 Years Ago [VIDEO]

The world's oldest continuously surviving cancer has been traced back to a single dog that existed some 11,000 years ago.

In a ground-breaking research, a team of scientists have successfully sequenced the genome of the world's oldest living cancer that has continued to exist within the dog population from the past 11,000 years. The cancer has over two million mutations, far more than the number of mutations in most human cancer cases, majority of which have some 1000-5000 mutations.

Led by researchers at the Wellcome Trust Sanger Institute and University of Cambridge, the team successfully decoded the DNA of the cancer, which is a transmissible genital cancer that affects dogs. This cancer is also known to cause grotesque genital tumors in the dog population around the globe. The first victim of the cancer passed on the disease via mating.

"The genome of this remarkable long-lived cancer has demonstrated that, given the right conditions, cancers can continue to survive for more than 10,000 years despite the accumulation of millions of mutations," Dr Elizabeth Murchison, first author from the Wellcome Trust Sanger Institute and the University of Cambridge, said in a statement.

On decoding the DNA, the genetic variants revealed that the ancient dog resembled an Alaskan Malamute or Husky. The medium sized dog probably had a short strait coat that was either grey brown or black in color. But, the genetic sequencing failed to determine whether the infected ancient animal was a male or female. The genetic analysis has hinted that it was a inbred animal.

"We do not know why this particular individual gave rise to a transmissible cancer," says Dr Murchison, "But it is fascinating to look back in time and reconstruct the identity of this ancient dog whose genome is still alive today in the cells of the cancer that it spawned."

The new findings offer scientists  a unique insight into the spread of this transmissible cancer.

The researchers had even matched the patterns of the genetic variants with tumors from different continents. The analysis revealed that the cancer was present in just one isolated population of dogs for most of its history. It was within the last 500 years that the cancer spread to the world and was mostly carried by dogs that are accompanied by seafarers.

Such transmissible cancers are very rare. The other naturally occurring transmissible cancer is the facial cancer in Tasmanian devils that spreads via biting.

"The genome of the transmissible dog cancer will help us to understand the processes that allow cancers to become transmissible," says Professor Sir Mike Stratton, senior author and Director of the Sanger Institute. "Although transmissible cancers are very rare, we should be prepared in case such a disease emerged in humans or other animals. Furthermore, studying the evolution of this ancient cancer can help us to understand factors driving cancer evolution more generally."

The finding was published in the journal Science.