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Caution over contagious cancers -

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Caution over contagious cancers

The World Today - Monday, 20 October , 2008 12:50:00

Reporter: Felicity Ogilvie

ELEANOR HALL: Scientists have always assumed that cancer is not contagious in humans.

But a Tasmanian immunologist is now questioning that, using his experience of the deadly facial
cancer that has been spreading in the Tasmanian devil population.

Professor Greg Woods specialises in human disease but he's also been studying the Tasmanian devil
and warns that like the tumours that are killing the devils, human cancers could also become
contagious.

Professor Woods spoke to our Hobart reporter Felicity Ogilvie.

GREG WOODS: Well, the Tasmanian devil facial tumour disease is a series of what I call unfortunate
events with apologies to Lemony Snickets.

For it to happen in humans you would have to have a series of unfortunate events as well and
probably one of the closest situations would be a cancer cause in Africa called Burkitt's Lymphoma
which is caused by a virus, Epstein-Barr virus or EBV virus which in well-developed countries will
cause glandular fever, but in Africa where malaria is endemic, it can cause this lymphoma. That is
because malaria suppresses the immune system.

FELICITY OGILVIE: When someone's immune system is suppressed and they end up getting cancer, it
ends with that person. With the Tasmanian devils, it doesn't end with the devil that catches the
cancer, they pass it on to someone else. Is it possible that that would ever happen with humans?

GREG WOODS: Well, that's right. In devils, because their genetics are so similar, it is transmitted
between devil to devil. It is unlikely that it is going to happen in humans unless the whole human
race or the whole human population is severely immuno-suppressed and that is very unlikely.

FELICITY OGILVIE: Are many cancers transmitted via viruses?

GREG WOODS: Not a lot. Cervical cancer is one. Papilloma virus. There is a T-cell leukaemia virus
which can be transmitted and there are a few other minor viruses. It is not very common but it does
happen.

FELICITY OGILVIE: If some cancers such as cervical cancer and a certain kind of leukaemia, can
already be transported via a virus, is cancer already contagious in humans?

GREG WOODS: Well, it is not the cancer that is contagious, it is the virus and the virus will then
have to infect cells. Even if you get the virus, it doesn't mean you are going to get the cancer.
You may just get a little papilloma or nothing may happen. For that papilloma to become a cancer
cell, you need some other mutation events which is sort of independent of the virus.

So the transmission of the virus won't necessarily cause the cancer; you just have to have some
other unfortunate events to occur for that cell to become cancerous. So the virus is transmitted,
not the cancer.

FELICITY OGILVIE: Have immunologists such as yourself started considering the possibility that
cancer in humans could become contagious after seeing what's happened to the Tasmanian devil?

GREG WOODS: Um, that is a good question. I'll let you know a scenario in that, about 50 years ago a
new protein was discovered. It was called, it caused a disease in the tribes of New Guinea,
tribesmen were getting neuro-degenerative diseases which was caused by a protein and we now know
that to be a prion. Now that case they were never thought that proteins could be infectious and
proteins are certainly infectious and causes things such as Mad Cow Disease.

Now we have a cancer in Tasmanian devils which is infectious which has got us thinking again that
there is this slight possibility that cancer could be contagious. So we have to keep our eyes and
our minds open that maybe, maybe we don't know enough about this cancer; maybe there is a
possibility that this could become contagious. It could happen somewhere else in some population.
Anything is possible.

ELEANOR HALL: That is Tasmanian Immunology Professor Greg Woods speaking to Felicity Ogilvie in
Hobart.