Monday, June 6, 2011

Cancer In Animals

Yes, animals do get cancer. I just got to know that by the way.

Prominent biologist and blogger Carl Zimmer wrote that the mere existence of the largest of all animals, the Blue Whale, suggests that it is possible to suppress cancer many-fold better than what is currently done in humans.

Blue whales can weigh over a thousand times more than a human being. That’s a lot of extra cells, and as those cells grow and divide, there’s a small chance that each one will mutate. A mutation can be harmless, or it can be the first step towards cancer. As the descendants of a precancerous cell continue to divide, they run a risk of taking a further step towards a full-blown tumor. To some extent, cancer is a lottery, and a 100-foot blue whale has a lot more tickets than we do.
Some scientists modeled up cancer rate in humans and decided that "About thirty percent of all people will get cancer by the end of their life. Scientists have been able to build good models for the odds of developing certain forms of the disease."
Amazingly, some animals such as mice and sharks have cancer rates around the same value. This is an example of what biologists call Peto's Paradox; there seems to be no correlation between body size and cancer rates among animal species-meaning almost all animals share the same rate of getting cancer, regardless of the size of the animal.

When they ramped the model up to whale scale, they found out that the massive bulk of the animal means that by the age of 50, about half the whale should acquire cancer, and by the age of 80, all of them should have it.
This shows that we still have a lot to learn from Mother Nature; blue whales are known to live well over a century. Bowhead whales have reached at least 211 years. If blue whales really did get cancer as fast as the models would suggest, they ought to be extinct.

This means that blue whale or other whales have developed a secret way to fight cancer. Otherwise how could they live well over a hundred years with their massive size?
Hence, regardless of what the scientists found at the end of their studies (I don't really care), we can see that the chances of getting cancer is rather arbitrary. Neither Peto's Paradox nor the body-size-and-cancer-rate-relationship holds-- some animals do have the same rate but there are exceptions, subsequently making both models rather sloppy and unreliable. The ambiguous nature of cancer per se makes it rather difficult for scientists to tackle the disease, for now at least.


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