Among the Nagasaki atomic-bomb survivors registered at the Scientific Data 
Center for Atomic-Bomb Disaster, Nagasaki University School of Medicine, 45 
cases of surgically treated intracranial meningioma were collected from 6 
hospitals with departments of neurosurgery in or near Nagasaki City during the 
period from 1973 to 1992. All 45 patients were over 40 years of age at the time 
of diagnosis. Subsequently, the 45 cases were statistically analyzed in 
relationship to the estimated distance from the hypocenter by age, gender, 
intracranial location, histology and latent period. The analysis showed a high 
correlation between incidence of meningiomas and distance from the hypocenter. 
The incidence among Nagasaki atomic-bomb survivors over 40 years of age, 
especially in those proximally exposed, appears to be increasing, in inverse 
proportion to the exposure distance, since 1981, 36 years after the explosion of 
the atomic bomb.