Peto's Paradox: Cancer isn't as simple as you may think!

  In multicellular organisms like dogs, cows, cats, or humans, cells continuously go through various cycles of growth and division. When cells divide, they are supposed to copy over 6 billion pairs of DNA. And because it is a natural process, cells aren't infallible - it is fair to expect some mistakes that cells unavoidably commit while copying this data. These mistakes are referred to as somatic mutations.

  Each somatic mutation, regardless of at which stage it occurs, has a chance to undergo carcinogenesis; in other words, has a chance to cause cancer. If every cell division carries a certain chance that a cancer-causing somatic mutation could occur, then the risk of developing cancer should logically be proportional to the number of cell divisions in the organism, right? Therefore, large-bodied and long-lived organisms should face a higher lifetime risk of cancer simply because their bodies contain more cells and will undergo more cell divisions throughout their lifespan. This, it turns out, is not the case! 

  Logically as discussed above, bigger animals should have more chances of cancer, but studies show that bigger beings like blue whales are immune to cancer. This doesn't make any sense. Seems like, in the process of understanding cancer over the years, scientists came across a biological paradox: Peto's Paradox. So why is it so? Converse to the logic, why do bigger animals have little to no cancer? How is this even possible? 

  Lucky for you, you are reading Usual Queries. The one ultimate stop to get answers to questions you always wondered. Ah ok, that's too much!

  To understand how, we need to know more about cancer itself. The disease in which body cells undergo uncontrollable growth and gradually spread to other parts of the body is regarded as cancer. It is a genetic disease and the causes include errors during cell division, damaged DNA due to external substances, or inheritance.

Only the fittest will survive. - Charles Darwin

  Well, we can call off the paradox with a very simple solution: evolution. Yes, we all probably know how Darwin's theory works. He suggested that organisms that show the necessary adaptations to adapt to the surroundings survive and the species continue to exist, the rest perish and their species go extinct. Similarly, according to this explanation, species that were more prone to cancer didn't build immunity against it and went extinct. On the other hand, species that built the immunity continued to exist and we see them today as big beings immune to cancer. 

  As every paradox goes, this explanation doesn't have enough proof to support it.

  Luckily we do have another explanation, and this is likely the one we are looking for. This has to do something with the concept of hyper tumors. Just like hyper parasites are parasites on the body of a parasite, hyper tumors are tumors on an existing tumor, for example - cancer. Let's understand it in a better way. 

  When a cancer cell forms and starts to multiply, for its short-term benefits, it needs resources and nutrients to multiply itself. Instead of killing other cells, cancer cells form blood vessels around themselves and take nutrients from the body itself. As a result, they start to divide rapidly and spread.

  Wait, did you notice something? They divide to form more of themselves. And when there is division, there is a chance of mutation. In a big organism like elephants or whales, these divisions happen on such a large scale that there are chances of it forming a new tumor. Now instead of building its pathways around blood vessels, this new tumor cuts off paths to old cancer cells and nourishes itself. Yes! Cancer killing cancer. And maybe that's how big species get rid of cancer and are so immune to cancer. 

  Again, there is no solid proof to support this explanation. Well, it's paradox for a reason! Let me know in the comments below, what you think about today's probably fruitful discussion. I am sure you learned something new.

  Hey, fam! I am back after a long long break. But yeah, new, fresh and more quality posts will await you in the future. P.S: My posts won't be as disappointing as they used to be in the past, so stay tuned!

References:

• What Is Cancer? - NCI
• Peto’s Paradox: how has evolution solved the problem of cancer prevention? - BMC Biology
• Why Blue Whales Don't Get Cancer - Peto's Paradox - YouTube
• Peto's Paradox: Evolution's Prescription for Cancer Prevention
• Peto's paradox - Wikipedia

Posts before October 2021 have been marked as "Old Posts". Less likely, but they might have out dated or incorrect information, ugly looking bits of code, no labels, etc. Don't get me wrong, many of these posts are top-notch and interesting too.

I thought it would be better not to delete or revamp these posts, even if they suck. The bitter truth is that old works always suck, but I take that as a positive tool to convey that I am growing. Besides there's no better way to showcase my journey without these old, messy, poorly written posts!

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