Radiotherapy for eye cancer (ocular melanoma)

Radiotherapy uses high-energy rays to destroy the cancer cells, while doing as little harm as possible to normal cells. For eye cancer (ocular melanoma), you may have radiotherapy in either of the following ways:

• You may have a small radioactive disc put on the outside of the eye. This is called brachytherapy. It is the most common way of giving radiotherapy for eye melanoma.
• You may have it from a radiotherapy machine. This is called external radiotherapy. It sometimes uses specialised techniques.

You may have radiotherapy:

• as your main treatment – this is more common for uveal melanoma
• to shrink the melanoma before surgery
• after surgery or chemotherapy eye drops, to reduce the risk of the melanoma coming back – this is called adjuvant radiotherapy.

Adjuvant radiotherapy is usually a treatment for conjunctival melanoma.

External radiotherapy aims high-energy rays from a machine at the tumour. It destroys cancer cells in the area it is aimed at. It does not make you radioactive.

The main types of external radiotherapy used to treat eye melanoma are:

• proton beam radiotherapy
• stereotactic radiation therapy.

These are specialised techniques that help protect healthy tissue and protect your eyesight. If you have uveal melanoma, you may have external radiotherapy on its own. If you have conjunctival melanoma, you may have external radiotherapy and chemotherapy eye drops.

Proton beam radiotherapy uses proton radiation to destroy cancer cells. The proton beam is aimed directly at the tumour. This causes very little damage to surrounding healthy tissue.

Proton beam radiotherapy is only available in a few cancer hospitals in the UK. It is used to treat uveal and conjunctival melanoma. This is usually when the melanoma cannot be fully treated with brachytherapy because of its size or position.

You may need to have a mask or mould made before treatment. This is to help you stay still and in the correct position during your proton beam therapy.

Before treatment, you have an operation to attach tiny metal clips to the white outer wall of the eye. These clips are called tantalum markers. You have this operation under general anaesthetic. You cannot see the clips, but they show up on scans. This helps your doctors plan the treatment. Because the clips are harmless, they are left in place after treatment unless you find them uncomfortable.

You have proton beam radiotherapy in small doses. These doses are called fractions. Each fraction is given over a few minutes each day. You usually have proton beam radiotherapy for 4 to 5 days as an outpatient.

Stereotactic radiotherapy uses many small beams of radiation to target the tumour. It delivers high doses of radiotherapy to very precise areas of the eye. This reduces the risk of side effects. You may have it if proton beam radiotherapy is not available.

Before having stereotactic radiotherapy, you have an MRI scan. This helps doctors plan your treatment.

Your doctor gives you an injection of local anaesthetic to stop your eye from moving. You may need to wear a light-weight metal head frame to keep you in the correct position.

The treatment usually takes 45 minutes. You usually only need 1 session of treatment, as a day patient.

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