Researchers have found that radiotherapy helps in natural tumor control process. They said radiotherapy attacks and destroys cancer cells directly. When experiments were conducted on mice researchers identified an cell suicide enzyme, getting activated when struck by radiation. This enzyme destroys tumor nourishing blood vessels to die. Tumors cannot survive without oxygen and nutrient supply. While it was thought that damage to the DNA in the nuclei of tumor cells was the only way that radiation killed tumor cells, this research shows another radiation-induced pathway initiated when radiation strikes endothelial cells.