Definition of Retinoblastoma:

Retinoblastoma is a malignant tumor (cancer) of the retina (part of the eye) that generally affects children under the age of 6. It is most commonly diagnosed in children aged 1 - 2 years.

Causes, incidence, and risk factors:

Retinoblastoma occurs when a cell of the growing retina develops a mutation, causing it to grow out of control and become cancerous.

Sometimes this mutation develops in a child whose family has never had eye cancer, but other times the mutation is present in several family members. If the mutation runs in the family, there is a 50% chance that an affected person's children will also have the mutation. They will therefor have a high risk of developing retinoblastoma themselves.

One or both eyes may be affected. A visible whiteness in the pupil may be present. Blindness can occur in the affected eye. The eyes may appear crossed. The tumor can spread to the eye socket through the optic nerve. It may also spread to the brain, lungs and bones. This is a rare tumor, except in families that carry the RB gene mutation.