Clinical and epidemiologic characteristics of first primary tumors of the central nervous system and related organs among atomic bomb survivors in Hiroshima and Nagasaki, 1958-1995.

BACKGROUND

Analysis conducted in the Life Span Study (LSS) cohort of atomic bomb survivors in Hiroshima and Nagasaki found a significant dose-related excess of tumors of the central nervous system (CNS) and the pituitary gland. The objective of the current study was to evaluate clinical and epidemiologic characteristics of first primary tumors of the CNS and the pituitary gland in this cohort and to compare them with characteristics among other populations.

METHODS

CNS and pituitary gland tumors that were diagnosed between 1958 and 1995 among 80,160 LSS cohort members were ascertained through Hiroshima and Nagasaki tumor registries, autopsy reports, and other sources. Pathologists reviewed all available records and slides to verify histologic diagnoses. Poisson regression analysis was used to model background incidence rates allowing for radiation effects.

RESULTS

Meningioma was the most common tumor among clinically diagnosed tumors, followed by neuroepithelial tumor, schwannoma, and pituitary tumor. The overall incidence of these tumors increased initially with age but declined among the elderly. For all age groups and for both genders, incidence increased over time. By contrast, when tumors diagnosed at autopsy were included, incidence rose continuously with age and was stable over time.

CONCLUSIONS

The main characteristics of CNS and pituitary gland tumors diagnosed in the LSS cohort were consistent with the characteristics of "spontaneous" tumors observed in other population-based studies. The predominance of meningiomas over neuroepithelial tumors in the Japanese population was noteworthy and warrants further investigation. The secular rise in incidence of all clinically diagnosed CNS and pituitary gland tumors is most likely to be attributable to the increased use of new imaging techniques.