Scientists Ponder the Prospect of Contagious Cancer (cnbc.com)

Cancer causes many deaths each year, and anyone that's lost someone to cancer knows how painful and grueling it can be. The one saving grace is that it ultimately only kills the host. But is this changing? According to several recent papers, scientists have suggested that cancer could become contagious. Cancer cells could have the ability to metastasize, not just from organ to organ, but from person to person. While this is not an imminent threat, it has already happened in unusual circumstances.

Comments

See Tazmanian Devil cancer outbreak

[Anonymous Coward]

Apparently the Tazmanian Devils in Tazmania are currently suffering for a contagious cancer outbreak. Devils get into fights and claw each other's noses, the cancer cells transfer into the wounds and multiply. Screws up their faces.

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

So for humans, it would be sorta like a zombie-like plague...

Tasmanian Devil Facial Cancer is transmittable

[Harlequin80]

There is a nasty cancer which is decimating the population of Tasmanian Devils. It forms lumps and lesions in and around the mouth meaning the animal eventually starves to death. This cancer is spread through contact.

That said it is believed that a lack of genetic diversity is a major reason in why the healty devils body doesn't recognise the invading cancer cell as coming from another animal.

http://www.tassiedevil.com.au/...

Re:Tasmanian Devil Facial Cancer is transmittable

[fuzzyfuzzyfungus]

There is another transmissible cancer, in dogs that is an STD. Luckily for the dogs, it is substantially less aggressive than the Tasmanian Devil cancer, and while it spreads reasonably readily(estimates of the length of the cell line vary; but it is definitely the oldest living dog in the world, for certain values of 'dog') the host's immune system typically controls it well enough that it causes only minor symptoms or is asymptomatic.

There have been a few once-off transmissions of cancer in humans; but no (known) ones under 'natural' conditions. An improperly screened donor organ, followed by immunosuppressants? Sure. Surgeon accidentally cutting himself and tumor cells from the patient getting into the wound? I believe that that has been documented; but no known in-the-wild transmission of actual cancer cells.

Genetic diversity and human lifespan

[Mostly a lurker]

One puzzle is why evolution has resulted in humans (and the vast majority of other organisms) having a limited lifespan with frequent breeding. Superficially, it would seem more efficient to invest less in the ability to procreate, but permit unlimited healthy lifespans. I have an hypothesis which I think fits with the content of TFA. Frequent breeding allows natural selection to counteract emerging diseases. Where a disease evolves that threatens to wipe out a species, genetic diversity provides an excellent chance that some individuals will be resistant. These resistant individuals can breed to aid species regeneration after being decimated by such a disease.

Re:Genetic diversity and human lifespan

[mysidia]

A simple increase in lifespan won't cause more reproduction, unless it also makes people fertile for a longer number of years, and likely to reproduce more times.

Then there is the issue that evolution is like a simple hill climbing algorithm.

So evolution can get trapped at a local maxima and does not necessarily see that an increase in lifespan makes you more fit in the long run.

Re:If Hitler had won

[Anonymous Coward]

Um, nothing in the article said anything about cancer becoming airborne. I didn't think it was fear mongering at all. Instead, it suggested that cancer spreading from one host to another is within the realm of possibility and not that it's likely to occur in humans.

There are diseases that are transmissible in humans that can cause cancer. HPV is an example. The article makes it pretty clear that in just about every case there are enough defenses to make it impossible. For it to occur, it must be easy for cancer cells to pass from one person to another. Accidentally injecting oneself with cancer is a way for it to happen. The other example involved a person whose immune system was compromised and the source of the cancer was a parasite. Because conditions like this are rarely met, it's virtually impossible for cancer to be transmitted from one person to another.

It seems like there has to be an easy pathway for many cancer cells to move from one person to another. This is extremely rare. It also seems like compromising or fooling the immune system makes it far more likely to occur. This is far more likely to occur among animals than among humans. I think the article makes it clear that what's possible isn't likely nor is it a threat right now.

I don't get your criticism of the article.

Dogs

[xlsior]

There's also a canine cancer that transmits through sexual contact:

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

"canine transmissible venereal sarcoma (CTVS), sticker tumors and infectious sarcoma is a histiocytic tumor of the external genitalia of the dog and other canines, and is transmitted from animal to animal during mating."
...
"The tumor cells are themselves the infectious agents, and the tumors that form are not genetically related to the host dog.[1] Although the genome of a CTVT is derived from a canid (probably a dog, wolf or coyote), it is now essentially living as a unicellular, asexually reproducing (but sexually transmitted) pathogen.[2] Sequence analysis of the genome suggests it diverged from canids over 6,000 years ago; possibly much earlier"
...
"believed to be the longest continually propagated cell lineage in the world"