Abstract 2291: Incidence of intracranial germ cell tumors by race in the United States, 1992-2009: A potential link with autoimmune encephalitis?.
Authors: Poynter Jenny N. , Fonstad Rachel , Tolar Jakub , Spector Logan G. , Ross Julie A. 
Published: August 2014

Abstract
Introduction: Pediatric germ cell tumors (GCTs) are rare and heterogeneous tumors that are grouped together due to their presumed common cell of origin, the primordial germ cell (PGC). GCTs typically occur in the testes or ovaries; however, abnormal prenatal PGC migration along with lack of apopotosis can result in tumors in extragonadal locations, including the central nervous system (intracranial and intraspinal GCTs; iGCTs). Little is known about the etiology of iGCTs, although international incidence data suggest that the highest incidence occurs in Asian countries. Autoimmune encephalitis (AE) is a paraneoplastic event characterized by abnormal behavior, seizures, and movement disorders; a number of case reports find AE in conjunction with GCT. We note with interest that a recent registry based study in California reported the highest incidence of AE in Asians. In this analysis, we used 1992-2009 data from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) Program to determine whether the increased rates of iGCT observed in Asian countries was also seen in Asian/Pacific Islanders living in the United States. Methods: Frequencies and incidence rates were evaluated for the entire cohort and for demographic subgroups based on sex, age category (0-9 and 10-29 years), race (white, black, American Indian/Alaskan Native and Asian/Pacific Islander), and tumor location (pineal gland vs. other) as sample size permitted. Analyses were conducted using SEER*Stat 7.1.0. Results: Two peaks in incidence were observed, the first before age 1 year in both sexes and the second at age 10 years for females and age 18 years for males. We observed a significantly higher incidence rate of iGCT in Asian/Pacific Islanders compared with whites (RR=1.98, 95% CI 1.51-2.56 for males and RR=3.21, 95% CI 1.99-5.05 for females) in the 10-29 year age group. This difference was observed for tumors located both in the pineal gland and for tumors in other locations. Conclusions: The increased rates of iGCT we observed in individuals of Asian descent in the SEER registry are in agreement with data from the International Agency for Research on Cancer, where the highest incidence rates were observed in Japan, Singapore, and the Maori population of New Zealand. The explanation for these rate differences has not been investigated to date; however, the increased incidence in individuals of Asian ancestry in the United States suggests that genetic susceptibility may play a role in etiology. The higher frequency of AE in Asians and the co-occurrence with GCT in case reports is also intriguing. It is possible that AE could be triggered by PGCs abnormally present in the cranio-spatial axis prior to GCT diagnosis, and it will be of interest to determine whether a diagnosis of AE precedes iGCT. These differences in incidence patterns by race and the possible link with AE merit further investigation.
Citation Format: Jenny N. Poynter, Rachel Fonstad, Jakub Tolar, Logan G. Spector, Julie A. Ross. Incidence of intracranial germ cell tumors by race in the United States, 1992-2009: A potential link with autoimmune encephalitis?. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2291. doi:10.1158/1538-7445.AM2013-2291