Contagious Cancer Found in Dogs

Dan East writes "Scientists in England have gathered definitive evidence that a kind of cancer in dogs, known as Sticker's sarcoma, is contagious. It is spread by tumor cells getting passed from dog to dog through sex or from animals biting or licking each other. Robin Weiss and his colleagues did genetic studies on the tumor cells from 40 dogs with Sticker's sarcoma, collected from five continents, which showed that all the tumor cells are clones of each other. The parent cell probably arose in a domesticated dog of Asian origin — perhaps a husky — hundreds of years ago, and perhaps more than 1,000 years ago. A similarly transmissible cancer has recently been discovered spreading through populations of Tasmanian devils."

tasmanian devil & spreading cancer

[fredouil]

unfortunately this kind of cancer is not new, here in Australia, the Tasmanian devil are diying and will soon disapear. http://news.nationalgeographic.com/news/2006/02/02 27_060227_tasmanian.html [nationalgeographic.com]

How are these Cancer Cells?

[mochan_s]

It is spread by tumor cells getting passed from dog to dog through sex or from animals biting or licking each other. Robin Weiss and his colleagues did genetic studies on the tumor cells from 40 dogs with Sticker's sarcoma, collected from five continents, which showed that all the tumor cells are clones of each other.

So, all tumor cells are clones of each other and not related to the dog. How is this cancer? Isn't it just a regular pathogen then?

Your dog wants a condom

[mobby_6kl]

getting passed from dog to dog through sex ... or licking each other.

And it doesn't seem that human to human cancer transmission is impossible, too. This could be the next big thing once we've cured AIDS.

How common is Sticker's sarcoma, though? We have a dog, and although she's not getting to fuck like a rabbit, dogs often lick each other and sometimes bite.

Damn...I just lost my dog to cancer.

[ip_freely_2000]

A 9 year old Border Collie with an aggressive tumor in her front leg. This happened two weeks ago. She spent a lot of time playing with other dogs in the park. I'd hate to think that me wanting my dog to have some fun is what killed her. I'd hate to have to wonder and worry about this with my next dog.

Cancer clusters...

[Varka]

Perhaps this will turn out to be a partial explanation for the "cancer clusters" you read about every now and then. Varka

How does it evade the immune system?

[neatfoote]

My understanding was that normal cancers survive in the body because they're part of its own tissue, and are recognized by the immune system as normal body cells. If, as the article says, this sarcoma really is transmitted via the cancer cells themselves (as opposed to an infectious cancer-causing agent like a virus), then shouldn't the infected dog's immune system recognize the cells as coming from another dog and attack them?

Re:How are these Cancer Cells?

[LurkerXXX]

It's a parasite. The strange thing is their claim that after dog bites these "cancer cells clog up the jaw, and the poor animals die of starvation".

I can see how a parasite like this might get a free ride in the genital tract, but in the case if bites like this, the host dog's immune system should recognize these 'cancer' cells as foreign material and destroy them.

Tasmanian Devils have it worse...

[aapold]

Tasmanian Devils are being wiped out by a transmissable cancer called Devil Facial Tumor Disease [wikipedia.org], its a pretty hideous disease that eventually causes the animals to starve to death as they are unable to eat. It is transmitted when Tasmanian Devils fight each other. It is estimated 100% fatal within 12-18 months, it is estimated that over half of all remaining Tasmanian Devils in the wild have it, and it has decimated their population.

Cancer..... sounds more like a new life form

[jjh37997]

Weird..... these cancer cells have evolved an ability not only to metastasized to different parts of a dog's body but to other dogs too. At this point I really don't think we should call them cancer cells anymore..... they are a new type of free living organism.... like a parasite. I wonder why they are restricted to only infecting other dogs? Does interspecies transmission produce too much of an immune response in a different host?

confusing

[i_should_be_working]

FTA:
A cancer cell is usually an animal's or person's own cell..

..the cells are not genetically related to the dogs they are in -- proof that they did not arise from the dogs' own cells.

..all the tumor cells, no matter where they were collected, are clones of each other.

If every cell of this cancer is a clone, and not the dog's own cells screwing up, then I'd say this is more like an infection. An alien organism has invaded the dog's body and then replicates. What's the difference (in terms of the vector) between this and a bacterial infection (also single-celled)?

Re:How does it evade the immune system?

[Anonymous Coward]

Nice comment. You hit the nail of why this has made immunologists (and the general medical research community) very excited. It's a naturally occuring neoplastic growth that is 'non-self' but not recognised as such by the host immune system. Thus it either is able to mimic the host tissue and/or completely evade the immune system. Study of this and the tassie devil tumours may provide novel insights into ways to enable transplanted organs or cells to evade the host immune system. From diabetes to heart transplants it's another string to the bow of medical science.

test of species differentiation?

[stites]

These tumor cells will grow in any dog. It would be interesting to see if they will infect closely related species. Will they grow in wolves, coyotes, jackals, etc.? Are there any breeds of dogs which are immune to these tumor cells? Will they grow in prey bitten by a dog, such as rabbits? One possible use for these tumor cells could be to determine how closely other species are related to dogs.

----------------
Steve Stites

Re:How are these Cancer Cells?

[Red Flayer]

FTFA:

"I rather thought we might disprove this, but it came out the other way around," said Robin Weiss, of University College London, who led the study appearing in today's issue of the journal Cell. "It is clearly a dog tumor cell behaving absolutely like a parasite." Weiss called the tumor transmission trick "a curiosity of nature."

This isn't the first time that a communicable parasite has evolved from a host's own cells and/or cell contents. Prions [microbe.org], such as the ones thought to cause BSE, are another intesting example, possible even harder to classify -- enough so that they've been given their own classification.

I would think that though the diseases from TFA originated as cancers, they now behave like parasites, and should either be labeled as such or given a new designation all their own.

Re:It happens in humans, too.

[thebdj]

There is a HUGE difference. People with certain types of HPV may or may not get cancer. It is not a given. You are right to some degree in that the important thing is they have found A cancer that is contagious. Don't say all cancer is contagious that is for the sensationalist media to provide.

Doggie Cancer Kills

[blooba]

I borrowed my nickname "blooba" from my late dog. I lost him to cancer last year. I spent $10,000 trying to treat his mast cell tumors, and I think I gave him a few extra months of comfortable living before the fucking cancer metastisized like a fucking wildfire. Anyway the point I'm trying to make is that it wasn't until after I put him down that his team of highly trained veterinarian oncologists at Manhattan's most prestigous Animal Cancer Treatment Center told me that canine cancer has a 100% mortality rate.

I sure wish I had known that before I shelled out $10,000. Don't get me wrong. My dog was worth every penny. But it sure would have been better to know beforehand that there was absolutely zero chance of him surviving cancer.

The main problem is the lack of animal cancer research. The good doctors who treated my dog (and he had an entire team of surgeons and specialists) tried very hard, but they just don't have enough information. Doggies don't respond to chemo like humans do, and they don't respond to radiation like we do. The doctors have to play extreme guessing games with each patient. It's all trial-and-error.

Before he passed, dear old Blooba donated a sample of his blood for research purposes. He always was a generous soul.

Could cancer be a form of evolution?

[Anonymous Coward]

Is it possible that cancer is a form of evolution? If you think about it, a rogue clump of cells that somehow (1 chance in a gazillion) finds a purpose that extends an animals life and gets passed on as part of the genetic make up. Quite often cancer runs in families, unfortunately pretty much all of the time it is destructive and ends up killing. If one time it is useful then if might help a species survive.

Symbiotic relationships could occur in the same way. For example, Ruminants eat and rely on billions of micro-oraganisms to break the grasses down for them. Without these organisms, they would not live.
http://en.wikipedia.org/wiki/Ruminant [wikipedia.org]

The transmitable cancer in dogs and marsupials could conceivably turn into a symbiotic relationship instead of a destructive one one day.

Re:It's not even really LIKE a normal cancer...

[ajs]

Yes and no. I think the more interesting discovery is that there's a species of creature who's anscestry includes a highly evolved creature (dog) and yet is on-par in terms of lifecycle with some of the least complex (colonial microbes). This might cause us to re-think much of what we believe to be true about the evolution of simple species, which might well have gone through this reversion to single-cellular life form multiple times.

Then again, this might be rare enough that it has had little impact on the process. Hard to tell.

Re:Which is why...

[RsG]

Finally, for the cancer to spread in the way described, we must be talking about cells with a high degree of mobility. This can't be something attached to something, like a tumour, or it couldn't spread identically from organism to organism.

I could be way out of line here, but I'm pretty sure that metasticized cancer cells have a high degree of mobility in normal, non-contagious cancers. The ability to jump from one organ to another via bodily fluids doesn't seem that far removed from the ability to jump from one organism to another via those same fluids. So I don't think the distinction here is mobility.

Part of what's unusual about this strain of cancer is mentioned in TFA:

Studies suggest that, unlike most tumor cells, which contribute to their own demise by becoming increasingly genetically fragile, Sticker's tumor cells are remarkably genetically stable, perhaps explaining in part their evolutionary success.

So the cells are unusual, at least when compared to other forms of cancer.

Another thing I find odd is that the dog's immune system doesn't recognize these cells as foreign and attack them; one of the reasons that your own immune system has trouble attacking your own cancer cells is because they're identical to the host's. OTOH, they say the cancer isn't fatal in dogs, so it's quite possible that the immune system does limit it's development.

Re:Which is why...

[Reziac]

[Hat: I am a professional dog trainer and breeder with 37 years experience.]

I first noticed an apparently-contagious tumour in dogs about 15 years ago. Transmission seems to require direct contact (not necessarily venereal), and the growth is always located in or just under the skin. Superficially, it resembles an ordinary fatty tumour. Under the microscope it looks like it's not exactly benign, but not like a "hot" cancer either. I've never seen one develop into anything serious.

Re:tasmanian devil & spreading cancer

[landryraccoon]

A good attempt, but you started contradicting yourself too early in the post.

And even when natural selection is responsible, why is that "right"? Evolution has no ethics, it simply is. Moreover, even if we start from the assumption that natural selection is right (or is best not interfered with), how can we seperate it out from every other factor involved in an extinction? Death by evolution is like death from old age; it's not a specific cause, it's a general description of what went wrong.

Nothing can ever go wrong if your paradigm is evolution through random natural selection. Things just die. There is nothing ever wrong or unnatural about this, whether a human being was involved or not.

We are ourselves unnatural creatures. The natural state of humans is poor health, early death, superstitious ignorance and starvation. We're hunter-gatherers naturally. Do we view our deviation from evolution as wrong?

Two mistakes. One, human beings can't be unnatural, nor can our activities be unnatural. That would imply the possibilty of a non-natural cause or factor involved, which you already said can't exist. Pumping petroleum out of the ground, killing each other with cruise missiles and causing mass extinctions are all completely natural, the consequence of random evolution and all within the understood laws of physics. Thus, nothing we do can be wrong, nor can it be unnatural. Under an evolutionary paradigm, how can the natural state of human beings (or anything else, for that matter) be anything else than what it is? Secondly, by definition, a human being can't deviate from evolution, becuase again, that would imply a non-naturalistic cause or involvement, which can't exist. Everything we do is part of the natural course of our evolution. Finally, if there WERE some way to deviate from evolution, there is certainly no way it could be described as "wrong", except under some sort of arbitrary cultural and human constructed ethical viewpoint.

And even if the tasmanian devils are dying out purely due to non-human factors, what arguement is there against trying to preserve them?

There are plenty of arguments on both sides, I'm sure, but as far as evolution is concerned, there is no argument for or against preserving them.

If you want to argue that the only species we have an obligation to preserve are the ones that our own actions have endangered, then that's fine - you're entitled to your own point of view. However, I don't agree with that line of thinking. The fact that we're probably blameless in the fate of the tasmanian devil doesn't mean we have no cause to preserve them.

Ok, now you've totally lost it. Species can't possibly have any obligations under evolution. You survive and reproduce, or you don't. Do tasmanian devils help us survive and reproduce? Maybe. Do we have an obligation to the tasmanian devil, or any other species? Maybe. But I don't see how. I assume that to continue arguing in favor of saving species, you would have to appeal to some sort of religious entity, or an arbitrary and culturally constructed ethic which uses words like "right", "wrong", and "should"?

Re:For that matter...

[stonecypher]

I mean, part of the whole problem with cancer is that the cells are in fact your own cells, so your body never attacks the infection.

Actually, the human body attacks cancers with an amazing speed and dedication. That's why when you get an immune suppressive disease like HIV, GRID or Hep C, you start getting all these weird cancers that nobody ever gets. The most common in the case of AIDS patients is Kaposi's Sarcoma, which is caused by a strain of herpes that we all have (HHV-8,) because once our natural resistance to KS is gone, it spreads like wildfire. Doctors suggest that we each actually get two cases of KS every week, and that we just give the cancers the beat-down.

Similarly, there are many cases in which the body attacks its own cells - sometimes by design, such as immune response to a cut, where the white cells kill themselves to provide the mass for a seal (pus and yellow scabs,) in tumor and growth suppression, to prevent bone spurs, etc; sometimes by disease, such as with lupus, perineoplastic syndrome and so on.

I mean, it's hard to even transplant a finger in a human without using huge amounts of anti-rejection drugs.

That's because legitimate tissue is covered in markers, so that they're easy to tell apart. These cells, like parasites, simply don't express almost any such markers. It turns out that our immune system ignores what it can't identify, and in this specific case, these tumor cells have become remarkably adept at hiding their identity. They're like Russian spies: they just blend in really well, and so nobody singles them out.

How is there a tumor growing inside the dog, with cells that must have a totally different DNA and chromosone pattern?

The immune system can't check DNA.

Why is the dog's host system not attacking it?

Because it doesn't know they're foreign. Parasites do this all the time; the human immune system manages to miss several dozen bloodworms (tape worms but in your veins, and six meters long) in the average equatorial African. The immune system doesn't get patched every friday, like your virus checker does; the only way to get something into it is if it makes a big enough difference for the change to provide an evolutionary advantage. Very few parasites are noticed by the immune system; the ones that are are the ones that are either there briefly, presumably to eat, or the ones which are strong enough to fight off the host's immune system, which is rare.

By the by, that's why sickle cell anemia isn't actually a disease. It's a partially complete adaptation: malaria can't kill someone with sickle cell, because it can't burst the oddly shaped cells. That two or three times in one's lifetime it might cause near-fatal crisis, because the sickle cells get stuck, is significantly less dangerous than being susceptible to malaria; indeed, that we're stepping in with medicine right now is unfortunate, because another two thousand years or so, and we'd be immune.