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

by girvo 5y ago

hn_throwaway_99 5y ago
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.
- KMag 5y ago
  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 https://en.wikipedia.org/wiki/Kaposi%27s_sarcoma
- bawolff 5y ago
  I wonder if such a cancer is less cancer, and more a parasite, from a certain perspective?
  - KMag 5y ago
    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.

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

by girvo 5y ago

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

hn_throwaway_99 5y ago

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.

KMag 5y ago
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 https://en.wikipedia.org/wiki/Kaposi%27s_sarcoma
bawolff 5y ago
I wonder if such a cancer is less cancer, and more a parasite, from a certain perspective?
- KMag 5y ago
  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.