How would a problem in mitotic division cause cancer

The most common form of cell division is called mitosis. It is used for growth and repair. During mitosis, a cell makes an exact copy of itself and splits into two new cells.

Mitosis is closely controlled by the genes inside every cell. Sometimes this control can go wrong. If that happens in just a single cell, it can replicate itself to make new cells that are also out of control. These are cancer cells.