Retinoblastoma is a tumor that develops in the retina. It is the most common intraocular malignancy in children. It most commonly affects children under the age of 5.
The most common sign is leukocoria. This refers to an abnormal white reflection in the pupil of the child’s eye. Generally, this leukocoria is only seen in specific circumstances: it varies with the direction of gaze, lighting, etc. When flash photos are taken, the unhealthy eye does not look the usual red color. Strabismus (child that squints/lazy eye) can be observed permanently and is a sign that the tumor is preventing the eye from correctly fixing on an object as the image is not able to project through the pupil. More rarely, exophthalmos is seen (where the eyeball protrudes from the eye socket).
The signs mentioned above should alert the doctor and a dilated eye examination should be performed. This dilated eye examination should be checked by an experienced ophthalmologist under general anesthetic. This examination is used to determine the size, location and number of tumors as well whether or not there is any involvement of the corpus vitreum. Disease staging is then carried out by means of a CT scan or magnetic resonance imaging (MRI) to supplement the initial assessment to ensure there is no optic nerve involvement.
Retinoblastoma treatment requires close collaboration between the departments of pediatric oncology, opthalmology, radiotherapy and interventional radiology in order to decide on the best treatment option for the child. The goal of treatment is to save the eye and as much vision as possible.
There are different types of treatment which can be combined to obtain the best outcome. Local treatments are always carried out under general anesthetic.
- Cryotherapy: the use of extreme cold to destroy small tumors (formation of an ice cube).
- Brachytherapy: destruction of medium-sized tumors using a radioactive plate.
- Photocoagulation: coagulation of the small vessels supplying the tumor.
- Thermochemotherapy: combines local destruction using a laser beam with intravenous chemotherapy. The combination of these two techniques enhances the effect of the chemotherapy on the tumor.
- Neoadjuvant chemotherapy: administration of chemotherapy before local treatments to shrink the tumor and make it more accessible to local treatments.
- Intraopthalmic chemotherapy: administered directly into the ophthalmic artery (via catheterization of the peripheral arteries) during local treatments.
Sometimes, it is not possible to save the eye because the tumor is particularly large or vision is already significantly impaired. Enucleation is then carried out. Examination under a microscope determines whether or not the tumor has spread, for example to the choroid or optic nerve. If it has spread, adjuvant chemotherapy is required.