Researchers at the Moffitt Cancer Center in Florida have found that cancer cells are not entirely random in how they spread, and they actually have specific functions depending on where they are. Using breast cancer cells as their focus, researchers found that cells near the center of a tumor have the ability to better use resources to ensure the tumor can grow and the cells closer to the outside of the tumor have better invasion techniques that equal a better chance at metastasis.
It's been thought that cancer cells are random mutations and their spread is a result of this unknown kind of mutation, but it's actually true that cells develop with an evolutionary focus on strength and survival. The team likened this growth to an invasive species of toad in Australia. Each toad in a group evolves to serve a specific purpose so the whole bunch can achieve success.