A cell is the smallest structural and functional unit of an organism. How beautifully designed is the blueprint of a cell that every time you put your microscope above it, you discover something that you never fascinated before. But, its these fascinating microscopic structures that lead to one of the most dreaded diseases of human race i.e cancer. In layman’s terms, cancer can be very conveniently defined as the uncontrolled growth of cells leading to formation of tumours.
But scientifically speaking, its not just the uncontrolled growth that leads to cancer, rather, its the size of organism that defines the fate of cancer. Most of us are familiar with the concept of contact inhibition displayed by normal cells. The property, by the virtue of which, normal cells check and prevent uncontrolled divisions. This, however is a feature which is absent in cancerous cells, which renders them to carry out infinite number of divisions and thus making them a potential initiator of cancer.
For starters, it can be inferred that as the number of cells increase, the probability of cancer should also increase. That is, increasing the complexity should give more and more chance for a normal cell to turn into cancerous. But, that’s exactly opposite of what scientists have observed. For eg: if you were to experiment on a rat, a human and a shark, the chances of either of them dying due to cancer would be highest in rats and lowest in sharks; in fact, sharks show almost negligible chances of death due to cancer. This inverse law which disobeys the hypothesis of larger animals being less prone to cancer then the smaller ones is known as Peto’s Paradox.
Explanations:
To explain this paradox, there have been broadly two concepts signifying the same:
1. The concept of Evolution: According to this hypothesis, evolution framed the structural biology of organisms in such a way that every organism with increasing complexity and increase in number of cells, develops a counter mechanism which helps it in preventing cancer development. Had not it been the case, the evolution of unicellular organisms into multicellular ones would not have been favoured; thus, stopping the chain of advancement in organisms that is very much evident now.
2. Hypertumor cells: Lets understand this with a very practical example. Suppose you were employed in a MNC(Multi national company) and were being paid some handsome sum of money. Handsome enough to get your girl/guy their favourite dress/ play station/ xbox. But, your boss decides to increase the employee in the firm without having any proper source of income. This leads to decrease in the monthly payment that each individual used to receive. You being a revolting person, decide to create your own startup and to have a better future. Now consider the MNC to be the parent tumour, thus making you a product of the tumour. Your startup thus, will be another tumour, known as hypertumor which will fight against the parent tumour.
Simplifying the concept, hypertumor are segments of parent tumour which compete for nutrients and metabolism and thus lead to cooperative destruction of theirs as well as their parent tumours, thereby removing the overall concern for tumour from the animals body.