What is radiotherapy?
Radiation therapy (also called radiotherapy or X-ray therapy) uses high powered x-rays or radioactive seeds to kill cancer cells. The aim of radiotherapy is to cure cancer, where possible, whilst maintaining acceptable function and cosmesis. Radiotherapy can be used alone or with chemotherapy or surgery. Where cure is not possible, the aim is the relief of symptoms (palliation) of cancer, thereby improving the person's well-being.
Action of radiotherapy
Radiotherapy works by destroying cells, either directly or by interfering with cell reproduction using high-energy X-rays, electron beams or radioactive isotopes. When a radiated cell attempts to divide and reproduce itself, it fails to do so and dies in the attempt. Normal cells are able to repair the effects of radiotherapy better than are malignant and other abnormal cells. Thus, normal cells are able to recover from exposure to radiation and maintain integrity and viability better than malignant cells.
If the dose and delivery of radiotherapy are well chosen and the disease is localised to the region of treatment, the cancer dies, whereas the normal tissues survive and the patient is made well again. If fewer than all the cancer cells are killed, improvement may only be short lived and the cancer may regrow. Since normal tissues are less able to withstand the effects of further radiotherapy, repeated treatments at a later date are seldom beneficial.
What are the types of radiotherapy?
Types of radiation therapy include:
- External beam radiation is the most common form. This method carefully aims high powered x-rays directly at the tumour from outside of the body.
- Internal beam radiation uses radioactive seeds that are placed directly into or near the tumour. Internal beam radiation is also called interstitial radiation or brachytherapy.
- Radiation during surgery (intraoperative radiation) , which involves external beam radiation focused directly at the area that needs radiation during an operation.
- Systemic radiation, which involves a radioactive substance that can be injected into a vein. The substance travels throughout the body, delivering radiation.
What is radiotherapy used for?
Radiotherapy is the principal treatment for various skin cancers; cancers of the mouth, nasal cavity, pharynx and larynx; brain tumours and many gynaecological, lung cancers, and prostate cancers. Radiotherapy plays a leading role in conjunction with surgery and/or chemotherapy in breast cancer, bowel cancer, bladder cancer, Hodgkin's disease, leukaemia and lymphomas, thyroid cancer, childhood cancers, gynaecological and testis tumours, as well as many other cancers and certain benign conditions.
What are the side effects of radiotherapy?
Radiation therapy can have many side effects. These side effects depend on the part of the body receiving radiation, the dose of radiation, and how often the therapy is given. The side effects include:
- Hair loss
- Red, burning skin
- Shedding of the outer layer of skin (desquamation)
- Increased skin colouring (hyperpigmentation)
- Death of skin tissue (atrophy)
- Fatigue and malaise
- Low blood counts
- Difficulty or pain swallowing
- Changes in taste
- Increased susceptibility to infection
- Fetal damage (in a pregnant woman)