

Naked mole rats never get cancer - prat
http://www.newscientist.com/article/mg20327267.300-naked-mole-rats-may-help-cure-cancer.html?DCMP=OTC-rss&nsref=online-news

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mechanical_fish
Unfortunately, this is just a special case of a much more troublesome problem:
Although plain old laboratory mice _do_ get cancer, they may well do so via
very different mechanisms from humans.

A mouse weighs 20 grams. I weigh somewhere around 100kg. So I consist of
approximately 5000 times more cells than a mouse does.

The longest-lived mouse in recorded history [1] lived just over 5 years. Most
mice die of old age in a couple of years. The oldest humans live to be over
100. Thus, my cell lines will undergo somewhere between 20 and 50 more cell
divisions than a cell in a living mouse. [2]

What this means is that human cells have to be much better designed to resist
cancer than mouse cells. If humans were no more cancer-resistant than mice
we'd all be getting cancer as infants. And evolution hasn't bothered to design
mice that will resist cancer for fifty years, because no mouse has ever had a
chance to live to be fifty.

So while many of the basic facts of cancer are similar in mice and in humans,
eventually the details are bound to diverge. This is an uncomfortable fact for
researchers.

This also means that, while it's great for the mole rats that they don't get
cancer, that doesn't mean they're somehow more immune to cancer than the
average human. Even though mole rats are legendary for their longevity -- they
can live into their twenties [3] -- the average human has to be less cancer-
prone than a mole rat just to get through puberty without needing
chemotherapy.

\--

[1] Google: "Methuselah Mouse Prize"

[2] This is a really simplistic calculation: Among other things, we're
neglecting the fact that mice have a rather different metabolic rate from
humans, and that different kinds of cells divide at different rates.

[3] Metabolism again: One reason that mole rats are thought to live so long is
that they have very _slow_ metabolic rates. Which probably also affects their
susceptibility to cancer.

~~~
stcredzero
_A mouse weighs 20 grams. I weigh somewhere around 100kg. So I consist of
approximately 5000 times more cells than a mouse does._

Another fun fact, whalers find tumor scars in whale bodies all the time, but
the whales never seem to die of cancer. The probable answer: whales are just
too big to care. If I get a tumor the size of a walnut, I might be able to
live with it. For a mouse, that would be a disaster. If I get a tumor the size
of my head, that's probably game over. But for a whale, it's no big deal. But
a mouse, a whale, and a human all have about the same sized cells. So to be
fatal, a whale's cancer cells would have to divide a lot more times.
Unfortunately, cancer cells experience a lot more mutations than normal ones.
Whales are big enough to be able to afford to let the tumors mutate themselves
to death.

~~~
mechanical_fish
I like this example.

But it's not just that the whales are too big to care. In fact, according to
published results from folks like the late Judah Folkman, human bodies are
_also_ full of little microtumors. The older you get, the more of them there
are.

Current theory is that microtumors are forming all the time, but most will
remain dormant forever. Only if one of them manages to "flip the angiogenic
switch" -- undergo a mutation which makes it able to summon new blood vessels
to itself -- will that tumor manage to grow to a size larger than a few
hundred microns in diameter. And even then it might not be that big a deal. I
guess whales can shrug them off at even bigger sizes than we can.

The problem is when the cancer learns to metastasize. In the immortal
(paraphrased) words of cancer researcher Josh Fidler, "if you have a big
primary tumor we know what to do: The surgeon cuts it out and off you go."
It's not the primary tumor that kills you. It's the metastases that kill you.
I bet whalers don't find whales full of metastatic tumors. Unless they're
already washed up on a beach.

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kqr2
It also appears that people with down syndrome have lower rates of cancer:

[http://www.eurekalert.org/pub_releases/2009-05/chb-
wdp051809...](http://www.eurekalert.org/pub_releases/2009-05/chb-
wdp051809.php)

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wyday
Where's the full article? All I see is an introduction.

~~~
prat
I am not sure of the source of this post (newscientist - they haven't
mentioned any references) but I found a paper describing the new animal model
using naked mole rat in the area of aging. The paper also talks about highly
reduced incidence/severity of cancer.

"The Naked Mole-Rat: A New Long-Living Model for Human Aging Research"
[http://biomed.gerontologyjournals.org/cgi/content/full/60/11...](http://biomed.gerontologyjournals.org/cgi/content/full/60/11/1369)

