Transmissible cancers -- cancers which can spread between individuals by the transfer of living cancer cells -- are believed to arise extremely rarely in nature. One of the few known transmissible cancers causes facial tumors in Tasmanian devils, and is threatening this species with extinction.

Scientists report the discovery of a second transmissible cancer in Tasmanian devils. The discovery, published in the journal Proceedings of the National Academy of Science, calls into question our current understanding of the processes that drive cancers to become transmissible.

 This type of  cancer spreads rapidly throughout the animal's body and the disease usually causes the death of affected animals within months of the appearance of symptoms. The cancer has since spread through most of Tasmania and has triggered widespread devil population declines.

Researchers have identified a second, genetically distinct transmissible cancer in Tasmania devils. This cancer causes facial tumors that are grossly indistinguishable from those caused by the first-described transmissible cancer in this species; however, tumors derived from this second clone are genetically distinct.

These findings indicate that Tasmanian devils have spawned at least two different transmissible cancers, and suggest that transmissible cancers may arise more frequently in nature than previously considered.

http://www.pnas.org/content/early/2015/12/23/1519691113.abstract?sid=f2c7a992-a2b4-40a5-814f-bc15d3ffa7a6