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Comment by mgerullis | Hacker News Reader

I have never heard of transmittable cancer before. Are there transmittable cancers among humans?

There is a theory that some (now) parasites were actually transmittable cancers before, which then developed multi-cellularity that allowed them to have the distinct cell types that they needed to be an own lifeform. Developing multi-cellularity in eurkaryotes has been reported a few dozen times if I remember correctly. Crazy stuff, if true.

that's one of the craziest theories I've ever heard (and amazing if correct!) I found this article https://link.springer.com/content/pdf/10.1186/s13062-019-023... but I still haven't read it!

Here's another for you - the virus-first hypothesis posits that all cellular life on earth is the result of viruses.

https://en.wikipedia.org/wiki/Viral_evolution

https://www.nationalgeographic.com/science/article/140716-gi...

I don't believe there's any known human ones, but there's a dog one that is 11,000 years old (Canine Transmissible Veneral Tumour) and there's a clam one.

The dog one is rampant where I live in Mexico. Treatable of catched early and the dog is lucky enough to have someone affluent watching over it, but most don't.

What name(s) do you have for it? What's the philology?

https://es.wikipedia.org/wiki/Tumor_ven%C3%A9reo_transmisibl...

Whilst not directly defined as a transmittable cancer, the HPV virus family sure does come close.

https://www.who.int/news-room/fact-sheets/detail/human-papil...

The real interesting part is that DNA from the first devil to develop the tumor is living on forever in other individuals.

Due to the high mutation rates of tumor cells, it is unlikely the "same" DNA. And it definitely does not live forever if it wipes out populations. That degree of aggressiveness is not a good survival strategy.

In humans it's very rare and usually related to transplants e.g. https://pubmed.ncbi.nlm.nih.gov/12692543/

> Are there transmittable cancers among human?

I don’t think there are any known examples of cancer transmission (as opposed to transmission of viruses that cause cancer) in humans; leukemias have shown to be transmissible in mice in the lab.

There kind of is—direct transmission of cancer has been documented mother-to-child (pregnancy) and as a rare complication of organ transplants.

It's also transmissible through a syringe

Cervical cancer is usually caused by HPV. So women can prevent it by getting vaccinated

I believe the question implied it was about non-viral transmissible cancers

To be fair I also never heard of viral cancer before either. Imagine an epidemic of transmittable, viral cancer among humans.

Though that is a virus that causes cancer, whereas the cancer under discussion is transmitted directly. Splitting hairs though, IMO!

I think it's a lot more than just splitting hairs.

There are many viral-initiated cancers. The virus is transmissible, and then when the virus infects host cells in causes the DNA machinery of the cell to go haywire, leading to cancer. Examples include HPV (causes cervical, anal and throat cancer) and feline leukemia virus (retrovirus which causes weakened immune system and leukemia in cats).

This is very different from a transmissible cancer, where it is the cancer cells themselves that can infect other hosts, which is pretty crazy when you first think about it. According to wikipedia there are only 3 known types among mammals: canine transmissible venereal tumor, devil facial tumor, and another cancer that affects Syrian hamsters.

There's also Human Herpes Virus 8 that causes Kopsi's Sarcoma[0]. Nearly all cases are found in immunocompromised individuals, and in times/places without HAART readily available, it is/was a common cancer in HIV+ people. In these cases, in some sense a co-infection of HHV-8 and HIV causes the cancer.

[0] https://en.wikipedia.org/wiki/Kaposi%27s_sarcoma

I wonder if such a cancer is less cancer, and more a parasite, from a certain perspective?

For pretty much any A and B, you can create a perspective from which A is like B. The interesting question is "in which cases does this perspective give useful insights or solutions?"

For treating a single animal, it's almost certainly useful to view it as a cancer. (Most drugs toxic to it will also be pretty toxic to the host, suppressing angiogenesis is helpful, etc.) From an epidemiology perspective, it probably behaves and spreads most like a bacterial infection. (Simple cell life cycle, limited environmental persistence, etc.) Parasites typically have a much more complex life cycle than these cells, and are much easier to target with drugs that won't harm the host.

So... maybe there's a use case where thinking of it as a parasite is useful, but it's not immediately obvious to me.

Just so you know boys can get the vaccine too to prevent them becoming carriers.

> prevent them becoming carriers

Avoiding passing the virus on to female partners isn't the only benefit for men. HPV also can cause penile, throat, and anal cancers in men. For instance, Michael Douglas has stated his throat cancer was caused by HPV acquired through cunnilingus.

And the FDA recently raised the age limit to 45! If you missed it when you get it’s now an option.

My uncle has terminal cancer after getting HPV in his throat from a woman who had it, 20+ years ago.

HPV causes cancer in men too (throat), and they should also be vaccinated.

Yes, and there are even vaccines for them:

https://www.mayoclinic.org/diseases-conditions/hpv-infection...

HPV is a virus (human papillomavirus) that can cause cancer, whereas with devil facial tumour disease the cancer itself spreads.

This means the cells that form the devil facial tumour are genetically identical across all individual animals infected with it. Normal cancer cells are your own cells which have developed a genetic abnormality, not somebody else's! As I understand it, an HPV infection increases the chance that one of your own cells will develop a genetic abnormality and become cancerous.

The distinction you are drawing is not relevant to the question or supported by the original claim:

>> The Devil Facial Tumour Disease" they suffer from is one of the few non-viral transmittable cancers.

That phrasing obviously contemplates the existence of viral transmissible cancers such as HPV.

If one person states "this is one of the few known non-viral transmissible cancers", and someone else follows up with the question "are there any transmissible cancers in humans?", how does information on transmissible cancers in humans get judged off-topic? Nobody asked "are there any non-viral transmissible cancers in humans?".

I read "are there any transmissible cancers in humans?" in the context as referring to cancers that are themselves transmissible like devil facial tumor disease. (It appears every result in the first few pages of a Google search for the term "transmissible cancer" refers to transmission of cancer cells themselves, not cancers caused by infectious agents.)

The context explicitly distinguishes "transmissible cancers" from "non-viral transmissible cancers". That's only possible when "transmissible cancers" includes cancers that are transmitted by viruses.

I can see both sides of this, though as a data point I also read it as "viral or otherwise".

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