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Radiotherapy Side Effects

How does it work?

Radiotherapy works by damaging the cancer cells in the treatment area. The aim of radiotherapy is to cause as much damage as possible to cancer cells and as little damage as possible to healthy cells. Radiotherapy uses high dose radiation to kill tumour cells with minimal damage to surrounding healthy tissue. Radiotherapy is fractionated (delivered daily over a number of weeks) and allows healthy cells to recover from small amounts of radiation damage. Unhealthy cancer cells are unable to recover from radiation damage and therefore they are destroyed.


The side effects caused by radiotherapy are usually localized to the treatment area. Radiotherapy has an accumulative effect and therefore the side effects will not start until the middle of your course of treatment, they will gradually progress and reach a peak 2-3 weeks after the completion of treatment. Your side effects should have subsided by your follow up appointment. The radiation therapists will advise you on how to minimize the risk of getting these side effects. It is important to follow this advice until your side effects have fully subsided. Your side effects will be monitored daily by the radiation therapists and weekly by your consultant. The most common side effects are a skin reaction similar to that of a sunburn and tiredness. Click here for more information

Late Side Effects

There is a risk of developing long term side effects. Research is being carried out to help radiotherapy clinicians understand more on the reasoning behind the development of long term side effects. Each radiotherapy treatment is planned with the intention to irradiate as many cancer cells as possible and to avoid irradiating healthy cells. This policy makes it is unlikely that you will develop late side effects from radiotherapy, however you need to be aware of the possibility in order to make an informed decision to have radiotherapy. Click here for more information