About retinoblastoma (Rb)

This section of our website has been written for parents of children who have been diagnosed with retinoblastoma (Rb). We hope you find this section informative and useful. If you are an adult who had Rb as a child, please see our section on Adults after Rb.

If you can’t find the information you are looking for here or have further questions please contact your support worker.

What is retinoblastoma?

Retinoblastoma (Rb) is a fast growing eye cancer of early childhood. This cancer develops in the cells of the retina, the light sensitive lining of the eye (see diagram). In the UK about 98% of children survive their retinoblastoma; this is true for both unilateral and bilateral disease. Nearly all of those with unilateral disease survive without further tumour. For those with bilateral disease there is, as explained in the section on 'second primary tumours', a risk that another type of tumour will develop in later life. Retinoblastoma has one of the best cure rates of all the cancers which develop in children.

Retinoblastoma occurs in two forms: a 'genetic' or 'heritable' form and a non-genetic, non-heritable form. Approximately 45% of children with retinoblastoma have the heritable form of the disease. When there is no previous family history of retinoblastoma, the disease is called sporadic.

In about two thirds of children, only one eye is affected, but in one third tumours develop in both eyes. When only one eye is affected, this is known as unilateral retinoblastoma, and when both eyes are affected it is called bilateral retinoblastoma. In some children who only have one eye affected at diagnosis, particularly those who are very young, it is possible for a tumour to develop in the second eye several weeks or even months after the diagnosis of retinoblastoma in the first eye.

The number of tumours found in the eye also varies: sometimes only one tumour develops however, there can be several tumours, and these may require more than one type of treatment.

How common is retinoblastoma?

Retinoblastoma is one of the less common cancers of childhood: in the United Kingdom it accounts for only about 3 out of every 100 cancers occurring in children under the age of 15 years. Between 40 and 50 children are newly diagnosed each year.

Retinoblastoma generally develops before 5 years of age and some children are born with the cancer.

What are the symptoms of retinoblastoma?

The signs of retinoblastoma include an abnormal appearance of the pupil, which tends to reflect light as a white reflex. This is usually only visible to the naked eye in low artificial lighting, or in photographs where a flash has been used. Sometimes children have a squint. Less common signs are deterioration of vision, a red and irritated eye without infection or a change to the colour of one iris.

If you are concerned, you should visit your GP or a local ophthalmology (eye) department and ask for an examination quickly.  A full diagnosis is only made after an examination under anaesthetic.

For full details on the signs of retinoblastoma (Rb) visit our Signs and symptoms page.

What causes retinoblastoma?

In children with the heritable form of retinoblastoma, there is something wrong with a small piece of the genetic material on chromosome 13, called the RB1 gene.  This affects all or many cells in the body. In some children with this form of retinoblastoma, the defective RB1 gene is inherited from a parent; in some cases, however, the defect in this gene occurs during the early stages of fetal development, some time before the child is born. It is not known what causes the abnormality in the gene to develop. It is most likely to be a random mistake in the copying process which occurs when a cell divides; such a mistake is known as a mutation.

Children with non-heritable retinoblastoma inherit normal RB1 genes from their parents. This form of retinoblastoma is also caused by a mistake (mutation) in the RB1 gene, but this mistake occurs as a random event in one cell within the retina.  This mistake then leads to a series of other genetic changes, which cause the retinoblastoma to form. Children with this form of the disease develop one tumour in one eye only and cannot pass on this mistake to their offspring.

Further articles which may be of interest:

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