Selective radiotherapy and photodynamic therapy: major advances in ocular oncology

The most common malignant intraocular tumour in adults is choroidal melanoma (the choroid is the layer that lies beneath the retina and nourishes it).

In some cases, it can grow without symptoms, while, in others, the patient can suffer reduced vision (if the tumour is near the macula, the central part of the retina), retinal detachment or intraocular haemorrhage, two processes that are commonly associated with choroidal melanoma.

Asymptomatic cases can be diagnosed with a routine examination of the back of the eye, "which everybody should have annually after the age of 50, when ocular tumours tend to start appearing," advises Dr José García-Arumí, a retina and ocular oncology specialist at the Instituto de Microcirugía Ocular in Barcelona. The most common treatment is brachytherapy, which involves the use of a radioactive ruthenium or iodine plate that is placed on the tumoral area for a few days.

As it is local, it prevents external radiation and minimises possible side effects. It is over 90% effective, if applied in the early stages, but, if not detected early, there is a high risk of metastasis, which mainly affects the liver, and has a mortality rate of 90%. In some cases, brachytherapy is applied in combination with endoresection, a surgical procedure that involves surgically removing the tumour by means of a laser and vitrectomy. It is sometimes necessary to cause a retinal detachment to gain access to the tumour and remove it with a laser and vitrectome (an instrument that breaks up the tumour and sucks up the fragments). Another type of tumour in the subretinal layer is choroidal haemangioma, a benign tumour, in which there is no risk of metastasis, but can develop rapidly and aggressively, posing a risk for vision, since it threatens the optic nerve (the transmitter of images from the retina to the brain) and the macula. Choroidal haemangioma is treated with photodynamic therapy, a technique that, until a few years ago, was applied to age-related macular degeneration. A study led by Dr García-Arumí demonstrated the effectiveness of the therapy to treat this type of ocular tumour. The treatment, which involves the intravenous administration of a drug and subsequent application of a laser, acts selectively on the tumour with minimal damage to the retina.

Retinoblastoma is another type of ocular tumour, which, in 50% of cases, is passed on from one generation to another. It affects one in every 15,000 newborn infants and is the most common malignant eye tumour in childhood. Treatment is usually a combination of radiotherapy and chemotherapy. "A selective treatment is currently being studied, which would involve the application of chemotherapy through the ophthalmic artery," explains Dr García-Arumí. "If it produces good results, we will have a treatment with fewer side effects," he adds. This type of tumour is highly aggressive, so early diagnosis and treatment are essential to save the eye and eliminate the need for enucleation (total removal of the eye).