Genome of 11,000-Year-Old Dog Cancer Decoded

Genome of the world's oldest continuously surviving cancer that still affects dogs has been sequenced. The research has shown the evolution and growth of this rare type of genital tumor in canines.

The cancer called canine transmissible venereal tumor (CTVT) first occurred in a dog about 11,000 years ago, according to researchers at the Wellcome Trust Sanger Institute and the University of Cambridge.

The genome shows that the cancer has over 2 million mutations, significantly higher than the number of mutations seen in human cancers. The newly sequenced cancer genome still has the genetic variant of the first dog that it affected. CTVT causes severe genital tumors in dogs.

"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", says Dr Elizabeth Murchison, first author from the Wellcome Trust Sanger Institute and the University of Cambridge.

Genome analysis has shown that the dog that first harbored the cancer might have resembled an Alaskan Malamute or Husky. Researchers couldn't find the gender of the dog, but have said that the dog was probably inbred.

Researchers also found that the cancer first occurred in isolated packs of dogs, but later spread to other continents after species spread during the "age of exploration."

Transmissible cancers are quite rare in nature. Apart from the dogs, Tasmanian devils suffer from cancers that can pass from animal to animal.

"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, according to a news release. "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 study is published in the journal Science.