Incidence of primary central nervous system germ cell tumors in childhood: a regional survey in Kumamoto prefecture in southern Japan.
BACKGROUND/AIMS
Central nervous system germ cell tumors (CNS-GCTs) are relatively rare. While their incidence was thought to be higher in East Asia than the USA, recent evidence suggests the difference between Japan and the USA is not statistically significant. The aim of this study was to determine the rate of pediatric primary CNS-GCTs in Kumamoto prefecture, Japan.


METHODS
We surveyed 6,615 new cases of primary intracranial tumors diagnosed in Kumamoto prefecture between 1989 and 2011. Among these, 251 (3.8%) occurred in patients younger than 15 years. The age-adjusted incidence rates were calculated by the direct method using 5-year age groupings; the incidence in the total Japanese population in the year 2000 was the standard.


RESULTS
During the 23-year period, 70 cases of primary GCT were diagnosed. Of these tumors, 31 (44.3%) arose in patients aged between 0 and 14 years (22 boys, 9 girls). Their tumor location was pineal in 45.2%; the other sites were nonpineal. There were more germinomas (64.5%) than nongerminomas (35.5%) in this group. The age-adjusted annual incidence rate was 0.45 cases (boys: 0.64, girls: 0.28) per 10(5) children. At 2.29, the ratio of CNS-GCTs was higher in these boys than girls. Our data showed higher rates than data from CBTRUS 2012 (0.18/10(5)), SEER 2008 (0.15/10(5)) and Germany (0.10/10(5)).


CONCLUSIONS
Our survey showed that the incidence of primary CNS-GCTs in children was higher in Kumamoto prefecture than in the USA and other Western countries, suggesting that racial backgrounds play a role.