Transmissible cancers are unusual diseases which occur when cancer cells themselves become infectious agents and spread through populations. Tasmanian devils, marsupial carnivores endemic to the Australian island of Tasmania, are susceptible to two transmissible cancers, known as Tasmanian devil facial tumour 1 (DFT1) and devil facial tumour 2 (DFT2). Both cancers spread between animals by the transfer of living cancer cells during biting, and both manifest as facial tumours. DFT1 occurs at high prevalence throughout Tasmania, and has caused significant Tasmanian devil population declines, leading to conservation concerns.
We have sequenced hundreds of DFT1 and DFT2 genomes, and are using these to understand the origins, evolution and spread of these cancers. Key findings include variation in mutation rate between DFT1 and DFT2, the discovery of a hypermutator strain of DFT1, and the identification of signals of positive selection in both cancers.