EPIDEMIOLOGY

The commonest eye cancer in adults is melanoma, occurring at a rate of about 7-8 new cases per million Belgian residents per year. This rate has not changed during the last twenty years. No trigger for ocular melanoma has yet been identified, although most cases develop from suspect nevi or “beauty spots”. The average age for onset of this disease is 60-65 years.

Each European country has an eye cancer reference centre. Our Ocular Oncology Unit has a wealth of experience in treating eye cancer, and is internationally recognised. Almost all ocular melanoma cases recorded in Belgium are referred to the Centre, as are most cases of retinoblastoma, the commonest eye cancer in children (1 case for every 20,000 births). The Ocular Oncology Unit currently welcomes patients from several neighbouring countries.

Treatment of ocular melanoma patients is determined during multidisciplinary meetings in which ophthalmologists, medical oncologists and anatomopathologists all take part. The optimal approach is thus decided upon, depending on the nature of the tumour, on the basis of up-to-date knowledge.

SYMPTOMS AND DIAGNOSIS

Intraocular melanoma is often discovered by accident. Starting in the choroid, the layer of vessels behind the retina, it leads to a detached retina, which causes visual problems. These however are not particular to cancer and are found in many other diseases also.

Intraocular melanoma is diagnosed during an examination of the ocular fundus, which shows the retina and choroid through a previously dilated pupil. This diagnosis requires considerable experience: it is not always easy to recognise a “suspect beauty spot”.

The image, called an ophthalmoscopy, is observed with the naked eye, and the imaging techniques, especially ultrasound and magnetic resonance, confirm a diagnosis in 99% of cases. A biopsy is not often required.
Needle biopsies are performed under local anaesthetic, sometimes as part of a research programme aimed at studying how the cancer behaves and at identifying certain genetic properties of tumours, which help with the prognosis.

Ocular melanoma must be diagnosed at an early stage: identifying the lesion early considerably increases the probability of successful treatment.

Ocular melanoma is a rare disease. Only a few centres in the world have sufficient experience to identify it early and provide optimal treatment using modern equipment.

TREATMENT 

Treatment starts within a week of the diagnosis. New techniques have been perfected in recent years, saving the eye in most cases and avoiding the need for enucleation (surgical removal of the eye).

Transpupillar heat therapy involves subjecting the tissues to a temperature between 45°C and 60°C in order to kill the melanoma cells. A laser beam is passed through the pupil and focussed on the tumour. This technique is used in the outpatients’ clinic and does not require admission to hospital or surgery. Transpupillar heat therapy sessions can be repeated if necessary. The treatment provided by the Cancer Centre’s Ocular Oncology Unit has enjoyed a success rate of 94%.

Contact radiotherapy offers a comfortable alternative to enucleation when size and location of an ocular melanoma make transpupillar heat therapy impossible. Contact radiotherapy, also known as curie therapy, involves placing radioactive grains (iodine 125) attached to a support plate, in direct contact with the tumour for a period of 3-4 days. In Belgium, this very specialised, ultra-modern technique is only available at the Ocular Oncology Unit in the Cancer Centre.
Contact radiotherapy can control tumours in 97% of patients. However, in 5-10% of cases it causes complications, which lead to enucleation. Sometimes, contact radiotherapy can be combined with transpupillar heat therapy to make treatment more successful.
The chances of useful vision remaining at the end of treatment depend mainly on the size of a tumour and its location in relation to the optic nerve and the macula (the central part of the retina).

Enucleation is still the only available option when the tumour is too large to be treated by any other means.

Progress made in localised treatment of melanoma still does not prevent metastases from forming elsewhere, usually in the liver. If metastases occur, the prognosis is less favourable. Research conducted at the Ocular Oncology Unit is now concentrating on “ducting” treatments, which, administered together with local tumour treatment, are aimed at reducing the risk of metastases.
An anti-tumour vaccination could prove beneficial in this regard. This vaccination is currently being studied as part of a European study co-ordinated by our Ocular Oncology Unit.

RETINOBLASTOMA

Finally, the prognosis for retinoblastoma, the commonest eye tumour in children, has also improved. Until very recently, retinoblastoma required removal of the eye. Now, however, initial chemotherapy shrinks the tumour, allowing focal treatment to be given through transpupillar heat therapy or contact radiotherapy.