Answer:
Apoptosis is defined as a programmed cell death and plays very important role in the removal of cancerous cells. Apoptosis is the process in which cell undergoes several processes and attempt sui-cide. Apoptosis do not cause any harm to human cells as it removes only unwanted cell.
Apoptosis can prevent cancerous cells by telling unwanted growth of cell to self destruct. Cancer cells are formed due to proliferation of cells and ignore the signals of self destruction to prevent apoptosis.
In Sally's case also, cancer cells ignored the signal of apoptosis and a tumor was found in her colon.