Incidence of retinoblastoma in the USA: 1975-2004

Worldwide incidence rates of retinoblastoma in children aged 0-4 years vary from a low of 3.4 per million in Bulgaria to a high of 42.5 per million in Mali. 1 2 Incidence rates have been noted to vary greatly within Asia (6.3 to 19.6) and Africa (10.6 to 42.5), while incidences in Europe (six to 12) and Australia (10.3) generally show less variability. Incidences in Central and South America range from 7 per million in Uruguay to 17.1 in Colombia. 1 2 A summary of published reports on incidence of retinoblastoma in the USA appears in table 1 .

Region	First author	Study period	Incidence
Live births	<5 years of age/million	<15 years of age/million
Michigan, USA	Falls 15	?	1:20 000
Ohio, USA	Macklin 16	?	1:24 000
USA	Devesa 10	1969-71	1:18 000	11.0
USA	Pendergrass 17	1974-6	11.0	3.6
USA	Tamboli 3	1974-85	10.9
USA	Young 4	1975-95	3.8
USA	Present study	1975-2004	11.8

To our knowledge, only two prior reports have assessed short-term trends in incidence of retinoblastoma in the USA. 3 4 In view of recent literature regarding the role of environmental factors in the incidence of retinoblastoma, we decided to examine the incidence of retinoblastoma over the 30-year period from 1975 to 2004 to investigate any trends that might have an environmental aetiology.

Using the Surveillance, Epidemiology and End Results (SEER) Program database of the National Cancer Institute, we analysed variations in age-adjusted incidence of patients with retinoblastoma in the USA over a 30-year period between 1975 and 2004. The SEER Program of the National Cancer Institute is the only comprehensive source of population-based information on cancer incidence and survival rate in the USA. The SEER Program collects data from population-based cancer registries and covers approximately 26% of the USA. The population covered by SEER is comparable with the general USA population. In our study, nine historical SEER registries were utilised, as these were the only registries collecting data for the entire 1975-2004 period. These registries cover approximately 9.5% of the USA population. 5

MATERIALS AND METHODS

The National Cancer Institute SEER Public Use CD-ROM for the period 1973-2004 was used. 6 Nine historical SEER registries were utilised. For both morphology (retinoblastoma = 9510-9513) and topography (retinoblastoma included...