Radiation Therapy

Cancer cells are hard for the body to recognise. If the body could recognise them as cancer cells, the immune system would attack them and kill them, and the patient would not have cancer. Cancer cells are cells that have acquired mutations in the DNA that cause them to multiply quickly while persuading the immune system they are healthy cells.
There is a treatment that targets cancer cells in preference to healthy cells and kills them.
Radiation therapy or chemotherapy uses gamma rays. Gamma rays tend to kill preferentially the cells that reproduce most quickly - cancer cells. Hair follicles also reproduce quickly, so patients undergoing chemotherapy tend to experience hair loss.
The dose that is use is important. If the dose is too high, many healthy cells are killed. If the dose is too low, not enough cancer cells are killed. The dose needs to be as high as possible at the site of the cancer and as low as possible elsewhere. There are two techniques for achieving this.
1. A radioactive source is placed inside the tumour, either by taking a drug or by surgery.
2. Beams of radiation can be aimed at the tumour from different directions.