Retinoblastoma

Retinoblastoma (abbreviated as Rb) is a cancer that develops in the retina of the eye. It is classified as either a heritable form or non-heritable form. In about two thirds of cases, only one eye is affected, while in the other third, tumours develop in both eyes. The amount and size of the tumours can vary for each eye.

Symptoms
The most common sign of retinoblastoma is an abnormal appearance of the pupil. Other less common symptoms include the deterioration of vision, a red and irritated eye, faltering growth or delayed development. Some children with retinoblastoma can develop a squint (commonly referred to as "cross-eyed").

Depending on the position of the tumors, they may be visible through the pupil. The pupil may also appear white or red in some cases.

Causes
In children with the heritable genetic form of retinoblastoma there is a mutation on chromosome 13, called the RB1 gene. The genetic codes found in chromosomes control the way in which cells grow and develop within the body. If a portion of the code is missing or altered (mutation) a cancer may develop.

The defective RB1 gene can be inherited from parents, however, the mutation can also occur during fetal development. While it is unknown what causes the gene abnormality, it is thought to most likely be a mistake during the copy process which occurs when a cell divides.

Treatment
The treatment of retinoblastoma varies from country to country. The first priority is to preserve the life of the child, then to preserve the vision and thirdly to minimize any complications or side effects of the treatment. Many treatment options exist, including chemotherapy, cryotherapy, radioactive plaques, laser therapy, external beam radiotherapy and surgical removal of the eyeball.