My uncle has just been diagnosed with Cancer in his face can anyone tell me what Radiotherapy is and what they

Radiotherapy is described on this page, along with lots of other pieces of information which you and your uncle need to know.

Radiation therapy:

http://www.cancer.gov/cancerinfo/radiati...

radiotherapy is where they apply radiation to the cancer in effort to kill it off.

Radiation is a kind of light. Think of it as light of an invisible color. It just happens to be a color that kills human cells.

So it destroys part of the body, and too much of it will kill you, and a lot of it can make you very sick. But if they do just a little bit at a time, it can kill off disease without surgical cutting, etc.