Most cancers take years to develop and often occur in people as they get older. This long process is mainly due to the cell’s protective mechanisms to keep cancer from developing. However, as cells age, the chance of accumulating harmful mutations increases and cancer cells can start to grow. Once the cells become cancerous, it can take years of continuous dividing for the cancer cells to produce a human tumor that is large enough to cause illness or migrate to other tissues. However, the long “incubation” period doesn’t mean that nothing is happening. Every time a person is exposed to a certain level of radiation, there is the potential for a mutation to develop in their DNA. As discussed above, the cell’s protective mechanisms try to get rid of cells with damaged DNA. But as more mutations occur in the DNA, the higher the chance that some of the damaged cells will escape this fate, and then replicate the mutated DNA.