In this paper we describe the epidemiology and family history status of 1601 children with retinoblastoma in Great Britain diagnosed 1963 to 2002. We summarise the practical consequences for diagnosis and counselling of developments in molecular genetics.
Methods Incidence rates were analysed according to year of diagnosis and tumour laterality. Cases were classified as heritable or non-heritable on the basis of laterality and family history of the disease.
Results There were 998 unilateral cases, 581 bilateral and 22 of unknown laterality. Bilateral cases tended to be diagnosed at a younger age than unilateral. All bilateral cases are regarded as heritable and 35% had a family history of the disease. 7% of the unilateral cases had a family history and are therefore heritable. Thus at least (41%) of our cases are heritable. This is an underestimate, since our data on family history are incomplete. For unilateral cases aged below one year the reported incidence rate increased significantly (p<0.0001) by about 2.5% per year; for the age group 1-4 years the average increase was about 0.5% per year (not significant).