Radiation therapy uses high-energy x-rays (or particles) to kill cancer cells. Radiation may be used after surgery to help keep the tumor from coming back. So this is called as adjuvant therapy. Two types radiation surgery: A. External beam radiation therapy (focuses radiation on the cancer from a machine outside the body). B. Brachytherapy: For this type of treatment, the doctor places a small source of radioactive material (often in the form of small pellets) directly into the cancer or into the airway next to the cancer. This is usually done through a bronchoscope, but it may also be done during surgery.