Answer
Cancer is a disease of the cell cycle because it comes about because the cell no longer responds to controls that take the cell systematically through the stages of the cell cycle.
Work Step by Step
Cancers no longer heed internal and external growth signals that tell it to stop growing and dividing. The cell cycle is tightly regulated at specific points in the cycle so that cells don't grow and divide out of control; this uncontrolled cell division can be quite detrimental to a multicellular organism.
