Tassie devil facial tumour is a transmissible cancer
On Monday this week The Conversation published a story under the headline “What’s killing Tassie devils if it isn’t contagious cancer?” ( TT HERE ) The article suggested evidence that the Tasmanian devil facial tumour disease (DFTD) is a transmissible cancer is inconclusive and instead, environmental chemicals could be to blame. This misrepresents the state of the science.
All the latest research points to the fact that the deadly DFTD is a transmissible cancer that originated in a female Tasmanian devil. A single cell in this devil (patient zero) developed into a cancer cell.
This is nothing unusual as cancers, whether they are devil or human, originate from a single cell. This single cell divided uncontrollably to produce a tumour (mass of cells).
DFTD developed mechanisms to avoid being killed by the devil’s immune system. Again, nothing unusual – cancer cells usually develop such strategies.
What is unusual about DFTD, though, is that it is transmitted between devils. The same cancer cells from patient zero have spread throughout most of the Tasmanian devil population, killing every devil infected.
The disease spreads
The first case was identified in the far north-east of Tasmania in 1996. Trapping trips instigated by the government’s Save the Tasmanian Devil Program and the University of Tasmania have monitored the disease as it spread south and west throughout Tasmania.
Each year DFTD has spread further. This pattern of spread is consistent with an infectious disease, rather than a disease caused by carcinogens present throughout the state. The far north-west of Tasmania remains disease-free.
Several independent lines of evidence support that DFTD originated as a single clone, from DFTD cells in patient zero. A study published in Nature in 2006 proposed devil-to-devil transmission of the cancer cells and the clonal origin of DFTD, based on chromosomal analysis.
More recent studies (including here and here) have indicated that all tumours share similar complex chromosomal rearrangement.
Read more, The Conversation HERE, where there are full hyperlinks
*Greg Woods is Professional Research Fellow at University of Tasmania
• Dr David Obendorf, in Comments: Going back over 10 years and knowing what we know about the science of the devil facial tumour today I am certainly disappointed at how [b]politically controlled[/b] this disease in Tasmania’s largest carnivorous marsupial became. In my opinion, the opportunities for ground-breaking research caused a feeding frenzy no less comparable to the competitive fighting bouts between hungry feeding devils that are regularly displayed to visitors to this island; so many skerricks and bits of knowledge about the beginnings of this malignant cancer were gobbled up before science could do them justice. The importance of knowing the genesis of this index event was discussed by credentialled scientists at the first science conference on the facial cancer in October 2003. The State government in 2003 did not want to explore the causal links for this unique transmissible cancer and that’s regrettable. I guess Tasmania being seen as [i]Clean, Green & Clever'[/i] precluded any official approval of research on the genesis of such a devastating, transmissible cancer. PS: There are other fatal cancers affecting free-living devils which have received lesser attention than this malignant Schwann cell sarcoma [aka DFTD].
• Steve Biddulph, in Comments: I’m with A.K. and Richard Kopf. Its not even an either/or situation. Most human cancers are lifestyle and diet related, thats the core message of cancer prevention in the western world. We’ve caused the diet of Tassie’s peak carnivores to be seriously contaminated both from water sources and the dead marsupials they feed on. At the top of the food chain is the place to see environmental harms accumulate first and most strongly. Thats a place we and the devils share. Cancers still mutate and occur frequently in all mammals but are dealt with by their immune systems when in good health. Compromise that, and it gives diseases a foothold. Nothing in ecology has a single cause or pathway. But keeping the environment free of non-understood new chemicals or genetics is a no-brainer.
• Andrew Ricketts, in Comments, HERE Tasmania is not clean or green. Killing quolls with 1080 fox baits was dumb. Proposed clearance of 2,000 Ha of high quality Devil and Quoll habitat in Welcome River catchment where there are healthy devils will, if it goes ahead, (and regardless of who owns it) never get a social license. If Chinese are buying VDL they should simply reserve that important natural forest under a Private Nature Reserve gazettal. Would gain much good publicity.
