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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). More than nine out of ten children with retinoblastoma can be cured, and it has one of the best cure rates (95-98%) of all the cancers which develop in children. How common is retinoblastoma?Retinoblastoma is one of the less common cancers of childhood, it accounts for only about 3 out of every 100 cancers occurring in children under the age of 15 years. In the United Kingdom, between 40 and 50 children are newly diagnosed each year. Retinoblastoma almost always develops before 5 years of age and some children are born with the cancer. Children with bilateral disease tend to present during the first year of life (the average age at diagnosis is 9 months), whilst the peak age of diagnosis for children with unilateral disease is between 24 and 30 months (average age at diagnosis is 28 months). Less than 5% of cases are diagnosed after the age of 5 years. What are the symptoms of Retinoblastoma?The most common symptom is an abnormal appearance of the pupil,which tends to reflect light as a white reflex, like a cat's eye. 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, pain, faultering growth or delayed development. It is possible to see tumours using an instrument called an opthalmascope. If you are concerned, you should visit your GP or optician and ask for an examination, but full diagnosis is only made after an examination under anesthetic. What causes retinoblastoma?In children with the genetic, ie the inheritable form of retinoblastoma, we know that there is something wrong with a small piece of the genetic material on chromosome 13, called the RB1 gene. Chromosomes contain the genetic codes which control the way cells grow and develop, and when a portion of the chromosome is missing or one of the genetic codes is altered in some way, which is known as a mutation, a cancer may develop. In some children with the genetic form of retinoblastoma, the defective RB1 gene is inherited from one of the parents, however, in the majority of cases, the defect in this gene occurs during the early stages of foetal development, some time before the child is born. We do not know 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. Some people worry this cancer is infectious, there is absolutely no evidence that anybody can "catch" retinoblastoma, and parents should reassure their friends on this account. For more information about the genetics of retinoblastoma visit our section on genetics here |
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