Final answer:
Cells that lose the ability to control their cell cycle and become able to divide uncontrollably are known as cancer cells. These cells may form malignant tumors that can spread throughout the body, contrasting with normal cells that undergo apoptosis at the end of their life cycle.
Step-by-step explanation:
Cells that de-differentiate, lose cell cycle control, and lose their attachment to surrounding cells are known as cancer cells. Cancer involves a loss of the ability of cells to control their cell cycle, the stages each eukaryotic cell goes through as it grows and then divides. When this control is lost, the affected cells rapidly divide and often lose the ability to differentiate into the cell type appropriate for their location in the body. In addition, they lose contact inhibition and can start to grow on top of each other, potentially forming a tumor.
It is essential to distinguish between a benign tumor, which is not cancerous, and a malignant one, which is cancerous and may spread. Cancer cells exemplify loss of cell-cycle regulation and uncontrolled proliferation, as opposed to normal cells which, when reaching the end of their life cycle, typically undergo apoptosis. This natural process of cell death is often circumvented by cancer cells, allowing them to multiply unchecked.