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CTVT – A contagious cancer that spreads from dog to dog
- JorgeGT 7y agoThe actual paper: http://doi.org/10.1126/science.aau9923 http://doi.org/10.1126/science.aau9923
- burtonator 7y agomutation, replication, natural selection. This is all you need for evolution. So evolutionary cancers makes sense once you add transmission.
- Reason077 7y agoSee also DFTD, which affects Tasmanian Devils: https://en.wikipedia.org/wiki/Devil_facial_tumour_disease https://en.wikipedia.org/wiki/Devil_facial_tumour_disease
- cmroanirgo 7y agoThanks. I was wondering if there was a correlation
- metafunctor 7y agoI was told in grade school that cancer is not contagious... well, turns out that was just lies to children. [1] This reminded me of the Radiolab episode “Devil Tumors” [2], featuring a similar kind of contagious cancer in Tasmanian Devils. [1] https://en.wikipedia.org/wiki/Lie-to-children https://en.wikipedia.org/wiki/Lie-to-children [2] http://radiolab.cs.odu.edu/radiolab-devil-tumors.html http://radiolab.cs.odu.edu/radiolab-devil-tumors.html
- deleted 7y ago[deleted]
- smt88 7y agoHuman cancers aren't contagious, at least not the way the cancer in the article is. Some risk factors for cancer, like HPV, are contagious in humans, but those aren't cancers themselves. The "lie" (which was not a lie at all) that you were told actually meant that you can't get cancer from being around someone with cancer. That's still true.
- ceejayoz 7y agoIt's largely true, and teaching it that way to school kids is important so they don't avoid friends/family who may have cancer of some sort. My son's friend has cancer and it was one of his first questions - "can I catch it?" The rare human cancers that are transmissible like cervical cancer get covered in sex-ed, and interventions like condoms are effective.
- arcticfox 7y ago> The rare human cancers that are transmissible like cervical cancer get covered in sex-ed Even cervical cancer isn't transmissible, just the HPV risk factor
- dcolkitt 7y agoClonally transmissible cancers are typically only seen in highly inbred populations. Tasmanian devils qualify because they went through a population bottleneck when they first colonized the island. Dogs qualify because of human breeding. (It's pretty unlikely that CTVT could be transferred to a wolf, even though pet dogs and wolves are the same species.) The reason most cancers aren't transferrable, is the same reason that organ transplants are so hard. Most individuals in most species have unique antigen profiles. The immune system attacks any foreign bodies without matching antigens. An internally generated tumor works because it's cloned from an individual's own cells. But a foreign tumor, is very unlikely to have a matching antigen profile. Therefore the immune system will attack and destroy with extreme prejudice. However a highly inbred population may lack the sufficient genetic diversity to have individually unique antigen profiles. In the extreme case if we were all clones we could pass tumors back and forth with ease. The short answer is that it would be virtually impossible to see any widespread cases of clonally transmissible cancers in non-immunocompromised humans.
- Loughla 7y agoSo if you have a population of humans who, for generations, have selected genes via inbreeding, would it be a thing to have transmissible cancer? I'm thinking of the Amish population near my hometown that has definite inbreeding traits and particular disabilities associated with inbreeding in their bloodline/families. Would it be possible for them to develop some kind of transmissible cancer?
- weinzierl 7y agoSo does that mean that cancer is contagious among identical twins?
- moftz 7y agoI suppose it depends on their individual immune systems. If they didn't live in close contact, they may not share the same immune system. One may have a weaker immune system than the other making it possible for the cancer to spread easily one way but not the other.
- 7y ago
- qtplatypus 7y agoHopefully grade school children are not at risk of ctvt
- idiocache 7y ago“It’s very mysterious,” Murchison says. “This cancer was exposed to something that caused this very particular mutation, and has never been seen in any human cancer ever, and that seems to have stopped 2,000 years ago. We don’t know what that carcinogen is, and we’d love to. I guess it was probably something in the dogs’ environment? This is a very crazy idea and we don’t really believe it, but maybe ancient people who owned the dogs tried to treat [their tumors] with some kind of chemical?” This feels wrong - surely particular carcinogens don't cause particular mutations. Isn't this just chance?
- idiocache 7y agoI didn't read the article properly, obviously. Thanks for the responses.
- bovermyer 7y agoThe article suggests that mutation patterns arise in predictable ways depending on the carcinogen, which is how they pinpointed the origin of CTVT to China.
- ppseafield 7y agoThe article states that different carcinogens do cause particular styles of mutation. > Many carcinogens mutate DNA in distinctive ways: Sunlight, for example, creates a very different pattern of mutations than cigarette smoke. Murchison’s team found that CTVT contains a lot of those sunlight signatures, especially at lower latitudes, where the sun is stronger. For example, CTVT in Mauritius has more sunlight-induced mutations than the same tumor in Russia.
- yread 7y agoParticular carcinogens absolutely do cause particular mutations or at least mutational patterns. Lookup mutational signatures. Signature 4 for smoking for example
- hwillis 7y agoThe most obvious way is that carcinogens affect parts of the body differently. Iodine collects in the thyroid, some compounds accumulate in the gut, alpha and beta affects the outer layers of the body. Epigenetics can cause different parts of DNA to be more or less exposed in different parts of the body. There are also indirect effects from chemicals- some carcinogens can cause changes in proteins, or be bound to proteins, which can cause them to be around certain regions of DNA more. Mostly though you see that kind of thing more in viral/bacterial cancers- a sizeable percentage of all tumors are caused this way.
- nso 7y agoThis is widespread with street dogs (and "street" dogs) where I live in Mexico. It can get pretty nasty. Female dogs will typically get tumor growths on the vagina, and at its worst will look like someone took a meat grinder to her parts. It will blow up in size and at some point the dog will succumb and die. The male dog will get it in the penis, and typically will be caught sooner as bloody discharge from a male dog is something that raises a red flag quicker. My mother-in-law has had 3 dogs get infected at different points in time, one female that had to be put down and two male that recovered.
- jjtheblunt 7y agoThat's sad, because it's trivially curable, supposedly. Man, if they'd snip those male dogs' with a vasectomy, what an improvement it would be...same here north of the mexico-us border.
- asdfman123 7y agoCan't you just avoid this if you spay and neuter dogs?
- nso 7y agoSure, but who pays for spaying and neutering the plethora of street dogs in the poorest states in Mexico? And many people have dogs without the means of paying for this (or any) kind of surgery. Between us and my MIL we have 10 dogs, and all of them except one are fixed. I've made sure of that. I'm not able to win the argument over the last one, but it's old now anyways. The dogs she had that got sick was from before I was in the picture.
- dymk 7y agoNeuter, not vasectomy. Vasectomy dogs still will mount, just not have puppies.
- kranner 7y agoOne of our dogs acquired a CTVT tumour in the nasal tract, which is rarer. It resulted in a bloody discharge via one nostril which thankfully led to an early diagnosis (although it remains curable up to quite a late stage as the vet told us). Our boy has had his chemo and seems fully recovered: swelling is gone, bleeding and reverse-sneezing have stopped, appetite is back to normal, all signs of lethargy and malaise are gone. Hopefully he will remain tumour-free.
- mbrumlow 7y agoSo if dogs have a caner that spreads deom dog to dog... Do humans have anything like that? If we did would this not cause a panic?
- CodeCube 7y agoWithout having read the article, and not being a biologist ... is this anything like HPV/Cervical cancer for humans?
- Retric 7y agoNo, this closer to the HeLa cell line. Initially it took significant effort to grow these cancer cells, but after evolution in a research environment now they easily contaminate other experiments. https://en.m.wikipedia.org/wiki/HeLa https://en.m.wikipedia.org/wiki/HeLa Similarly, a cancer that started in a specific dog ended up evolving to survive in different animals.
- astura 7y agoThe article addresses this: >To clarify, several cancers can be caused by infectious entities; cervical cancer, for example, is the work of HPV, a sexually transmitted virus. But in those cases, the cancer itself is not infectious and cannot spread. CTVT is different: Each cancer cell is a free-living parasite that can set up another tumor on another dog. HPV can also (rarely) cause cancers of the throat and penis.
- 3JPLW 7y agoThe third paragraph: > To clarify, several cancers can be caused by infectious entities; cervical cancer, for example, is the work of HPV, a sexually transmitted virus. But in those cases, the cancer itself is not infectious and cannot spread. CTVT is different: Each cancer cell is a free-living parasite that can set up another tumor on another dog. Put another way, HPV is a virus whose effects can cause cancer. That is, it causes mutations in _your own_ cells that cause them to become cancerous. CTVT is essentially a parasitic cell line — not your cells hopping a ride on you.
- ceejayoz 7y ago
- jcims 7y agoThis seems to stretch the definition of cancer. The tumors do not share DNA with the host, it's more like a bacterial infection or parasite.
- ceejayoz 7y agoThat's largely the point of the article, isn't it? That it's arguably its own species? > “CTVT is like its own organism,” Murchison says. “It isn’t really a dog. Is it a cancer, still?”
- jcims 7y agoMissed that, thank you.
- asdfman123 7y agoBut it's actual dog cells, which is wild. > Its future is uncertain, though. While failing to acquire beneficial mutations, CTVT is also failing to weed out harmful ones. That’s understandable, because much of its DNA comprises genes for building a dog
- privexpert5 7y agoIs anyone else terrified by this?
- ceejayoz 7y agoA six thousand year old cancer? Why?
- beat 7y agoNot as terrified as I was when one of our dogs got hemangiosarcoma, a canine-only cancer of the cells that line the inside of blood vessels. It took three weeks from the first symptoms to when he died. That's actually a long time - in many cases, the first symptom of the cancer is that the dog is dead.
- asdfman123 7y agoNah, it's actually extremely treatable and slow to mutate.
- asdfman123 7y ago> Its future is uncertain, though. While failing to acquire beneficial mutations, CTVT is also failing to weed out harmful ones. That’s understandable, because much of its DNA comprises genes for building a dog. It can afford to let those mutate into obsolescence. But over time, the genes that it still needs will also take hits. Slowly, the tumor will become weaker and less efficient. I wonder if there's an analogy to governments and laws. As our laws become more complex and "mutate," governments gradually become less effective.
- iskander 7y agoCoolest finding in the paper: "Our analyses reveal a mutational signature, signature A, that occurred in the past but ceased to be active from about 1000 years ago. A recent study (37) detected evidence for an excess of C>T mutations at TCC contexts, the mutation type most prevalent in signature A, accumulating in the human germ line between 15,000 and 2000 years ago. If this human mutation pulse is due to signature A, it could indicate a shared environmental exposure that was once widespread but has now disappeared." There will now be a small academic race to identify this mysterious carcinogen which both humans and this dog cancer were previously exposed to.
- throwaway5752 7y agoThree weeks ago: https://news.ycombinator.com/item?id=20590682 https://news.ycombinator.com/item?id=20590682 and https://news.ycombinator.com/item?id=20593109 https://news.ycombinator.com/item?id=20593109. One year ago: https://news.ycombinator.com/item?id=17489382 https://news.ycombinator.com/item?id=17489382. 5 years ago: https://news.ycombinator.com/item?id=7118621 https://news.ycombinator.com/item?id=7118621.
- thrownaway954 7y agoI send my dog to day care all the time. now I'm thankful that they require yearly shots and full examinations.