T H E INCIDENCE O F RETINOBLASTOMA SUSAN
S.
DEVESA,
M.H.S.
Bethesda, Maryland
Retinoblastoma is a rare tumor, although it is the most common eye tumor occurring during childhood. Some of the cases, par ticularly those involving both eyes, are due to transmission of a dominant gene from parent to offspring.1"2 Knudson8'4 proposed that two mutational events are necessary for the development of retinoblastoma, with the difference between hereditary and nonhereditary cases being whether the first event is a mutation occurring prezygotically or at the somatic cell level. The second mutation, which may be environmentally influenced, would be necessary for the manifestation of the tumor and would occur in somatic cells in both types of the disease. Jensen and Miller5 reported a marked racial difference in mortality from retino blastoma in the United States from 1960 to 1967, with black children experiencing a mortality 2j4 times that of white children at the peak ages of death, 2 and 3 years of age. However, retinoblastoma in its early stages is readily amenable to treatment, with fiveyear survival rates of 90% when the disease is diagnosed in the localized stage.8 Newell, Roberts, and Baranovsky," using data from Charity Hospital in New Orleans as well as from the End Results Evaluation Program at the National Cancer Institute, showed that at least part of the excess mortality among black children could be due to delayed diag nosis, resulting in more advanced disease at the time of diagnosis, and therefore a poorer prognosis. However, whether there is a ra cial difference in the incidence of retinoFrorn the Demography Section, Biometry Branch, National Cancer Institute, National Institutes of Health, Department of Health Education and Wel fare, Bethesda, Maryland. Reprint requests to Susan S. Devesa, National Cancer Institute, Landow Bldg., Rm B506, 7910 Woodmont Ave., Bethesda, MD 20014.
blastoma is questionable. Incidence data from the recent Third National Cancer Sur vey provide some information. METHODS
The Third National Cancer Survey was a project of the National Cancer Institute to gather information on all cases of cancer diagnosed during a three-year period (19691971) among residents of seven metropoli tan areas and two states (Atlanta, Georgia; Birmingham, Alabama; Dallas-Fort Worth, Texas; Detroit, Michigan; Minneapolis-St. Paul, Minnesota; Pittsburgh, Pennsylvania; San Francisco-Oakland, California; Colo rado ; and Iowa). This population comprises more than 10% of the total population of the United States. To assure complete and accurate reporting, various hospital re sources, including medical records, tumor registries, discharge indices, pathology and autopsy reports, and radiotherapy records, were utilized. The reporting for newly diag nosed (incident) cases of retinoblastoma was virtually complete as hospitalization is necessary for proper diagnosis and treat ment. However, all death certificates men tioning cancer were collected as well. It was unfeasible to query routinely all practicing physicians concerning their cancer patients; if a hospital record could not be found to substantiate the death certificate data, then the signing physician was requested to pro vide more information concerning the tumor, the date, and the method of diagnosis. In formation was also collected from the rec ords of private pathology laboratories and radiotherapy facilities. All abstracted data for a case were then consolidated and care fully edited. Methodologic details an further described elsewhere7; several mono graphs dealing with various aspects of th< survey data are in preparation.
263
264
AMERICAN JOURNAL OF OPHTHALMOLOGY
AUGUST, 1975
TABLE 1 RETINOBLASTOMA CASES BY RACE AND AGE, 1969-1971
Age at Diagnosis
Total Rate* No. of cases White Black Filipino Not recorded
61 SI 7 1 2
S.
DEVESA,
M.H.S.
Bethesda, Maryland
Retinoblastoma is a rare tumor, although it is the most common eye tumor occurring during childhood. Some of the cases, par ticularly those involving both eyes, are due to transmission of a dominant gene from parent to offspring.1"2 Knudson8'4 proposed that two mutational events are necessary for the development of retinoblastoma, with the difference between hereditary and nonhereditary cases being whether the first event is a mutation occurring prezygotically or at the somatic cell level. The second mutation, which may be environmentally influenced, would be necessary for the manifestation of the tumor and would occur in somatic cells in both types of the disease. Jensen and Miller5 reported a marked racial difference in mortality from retino blastoma in the United States from 1960 to 1967, with black children experiencing a mortality 2j4 times that of white children at the peak ages of death, 2 and 3 years of age. However, retinoblastoma in its early stages is readily amenable to treatment, with fiveyear survival rates of 90% when the disease is diagnosed in the localized stage.8 Newell, Roberts, and Baranovsky," using data from Charity Hospital in New Orleans as well as from the End Results Evaluation Program at the National Cancer Institute, showed that at least part of the excess mortality among black children could be due to delayed diag nosis, resulting in more advanced disease at the time of diagnosis, and therefore a poorer prognosis. However, whether there is a ra cial difference in the incidence of retinoFrorn the Demography Section, Biometry Branch, National Cancer Institute, National Institutes of Health, Department of Health Education and Wel fare, Bethesda, Maryland. Reprint requests to Susan S. Devesa, National Cancer Institute, Landow Bldg., Rm B506, 7910 Woodmont Ave., Bethesda, MD 20014.
blastoma is questionable. Incidence data from the recent Third National Cancer Sur vey provide some information. METHODS
The Third National Cancer Survey was a project of the National Cancer Institute to gather information on all cases of cancer diagnosed during a three-year period (19691971) among residents of seven metropoli tan areas and two states (Atlanta, Georgia; Birmingham, Alabama; Dallas-Fort Worth, Texas; Detroit, Michigan; Minneapolis-St. Paul, Minnesota; Pittsburgh, Pennsylvania; San Francisco-Oakland, California; Colo rado ; and Iowa). This population comprises more than 10% of the total population of the United States. To assure complete and accurate reporting, various hospital re sources, including medical records, tumor registries, discharge indices, pathology and autopsy reports, and radiotherapy records, were utilized. The reporting for newly diag nosed (incident) cases of retinoblastoma was virtually complete as hospitalization is necessary for proper diagnosis and treat ment. However, all death certificates men tioning cancer were collected as well. It was unfeasible to query routinely all practicing physicians concerning their cancer patients; if a hospital record could not be found to substantiate the death certificate data, then the signing physician was requested to pro vide more information concerning the tumor, the date, and the method of diagnosis. In formation was also collected from the rec ords of private pathology laboratories and radiotherapy facilities. All abstracted data for a case were then consolidated and care fully edited. Methodologic details an further described elsewhere7; several mono graphs dealing with various aspects of th< survey data are in preparation.
263
264
AMERICAN JOURNAL OF OPHTHALMOLOGY
AUGUST, 1975
TABLE 1 RETINOBLASTOMA CASES BY RACE AND AGE, 1969-1971
Age at Diagnosis
Total Rate* No. of cases White Black Filipino Not recorded
61 SI 7 1 2
