If surgery or medication are not completely successful at restoring growth hormone levels to normal, then radiotherapy may sometimes be used to try to reduce the growth hormone secretion of the pituitary tumour.
Radiotherapy can be effective but the irradiated tumour cells die very slowly over a period of many months or years and so the effects of treatment take time.
In the meantime, growth hormone and insulin-like growth factor 1 (IGF-1) levels may have to be controlled with medical treatments until the radiotherapy takes full effect.
There are different types of radiotherapy that may be used. All involve lying on a bed for positioning in a radiotherapy machine for a short time.
The radiotherapy treatment most frequently used is an external beam. Small doses of radiation are given for a few minutes each day for 5 days, usually Monday to Friday, for 5 to 6 weeks. The radiation beam is aimed with great precision from three directions at the pituitary tumour.
A transparent mask will be made for you to prevent your head from moving during the procedure. Do not worry; the mask will have big holes for your eyes and mouth.
Another approach is stereotactic radiosurgery, which uses a highly-focused single beam of radiation given as one, single dose to the tumour cells.
A lightweight head frame will need to be worn to ensure that the radiation beams are directed with precision to the tumour. The frame is held in position with four pins; a local anaesthetic is applied to the area where the pins are to be attached.
Stereotactic radiosurgery is a highly specialised treatment and so may not be available in all centres.
Radiotherapy may be used as part of the treatment plan for acromegaly
Radiation therapy can damage normal cells or structures surrounding the pituitary tumour, therefore it can lead to side effects.
Side effects of radiotherapy can include decreased production of other hormones produced by the pituitary gland. If this does occur, you can take replacement hormone therapy.
Rarely, there could be vision defects caused by radiotherapy.
The dose of radiation given is relatively small but some people may lose a very small amount of their hair where the radiotherapy beam was directed. This is temporary and the hair does grow back after the treatment is finished.
Although you will feel no discomfort or pain during external beam radiotherapy, you may feel tired and although some people continue to work, this may not always be possible.
With radiosurgery, some patients experience a mild headache or minor swelling where the head frame was attached, but most report no problems.
Read and hear answers to some common questions that patients with acromegaly have asked
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Information about the emotional, physical and social challenges of living with acromegaly