The two main forms of treatment for cancer are chemotherapy and radiotherapy.
Chemotherapy involves injecting or swallowing drugs that target the cancerous cells in the body. The drugs attack the harmful cells preventing them from reproducing and hopefully eventually killing them altogether.
The problem with chemotherapy is that the drugs also adversely affect the normal, healthy cells in the body which can lead to a variety of conditions from hair loss to a dangerously weak immune system.
However, once the course of chemotherapy is complete, these normal cells should recover very quickly and any side effects of the drugs will begin to clear up.
Radiotherapy, on the other hand, involves the targeted use of X-rays to eliminate a tumour (a build up of cancer cells). Radiotherapy is usually given before surgery to reduce the size of the tumour and make it easier to remove. Sometimes a mild dose may also be given to a patient to simply alleviate the pain caused by the cancer.
As you my be aware, there are health concerns associated with all forms of radiation but in terms of radiotherapy in the treatment of cancer, these are massively outweighed by the benefits.