Scientists say it's like an evolutionary throwback.
“Unlike bacteria and viruses, cancer has not developed the capacity to evolve into new forms. In fact, cancer is better understood as the reversion of cells to the way they behaved a little over one billion years ago, when humans were nothing more than loose-knit colonies of only partially differentiated cells.
“We think that the tumours that develop in cancer patients today take the same form as these simple cellular structures did more than a billion years ago,” he said.
In a way, the genes that controlled this early multi-cellular form of life are like a computer operating system's 'safe mode', and when there are failures or mutations in the more recent genes that manage the way cells specialise and interact to form the complex life of today, then the earlier level of programming takes over.