Answer: It uses ionizing radiations to kill the cancerous cells.
Step-by-step explanation:
Radiation therapy is commonly used in case of cancerous tumor because it has the ability to control the growth of cells. It damages the DNA of the cells and leads to cell death.
It either damages the DNA of cancerous cells or bombard charged particles in the cell that damages the DNA.
This is how malignant tumors can be treated with radiation.