Trial Information

A Case-Control Study of Testicular Germ Cell Tumors Among U.S. Military Servicemen

The incidence of testicular germ cell tumors (TGCT) has increased during the better part of
the twentieth century and is of particular concern as it primarily affects young men.
Though the tumor is relatively infrequent in the population as a whole, TGCT is the most
common cancer among U.S. males in the age group 15-34 years. Despite the increases in TGCT
rates, the etiology is still poorly understood. The only well described risk factors for
TGCT are cryptorchism, family history of TGCT and personal history of TGCT. Therefore, in
order to understand better the environmental and genetic determinants of TGCT risk, a
case-control study will be conducted among members of the U.S. Armed Forces. The study will
include men who have donated a blood sample to the Department of Defense Serum Repository
(DoDSR) between the years 1989 and 2003. All DoDSR donors who have developed GCT will be
matched to DoDSR donors who have not developed TGCT.

A total of 1682 servicemen were enrolled in the study; 754 cases and 928 controls. Of these
participants, 1303 men (77%, 590 cases, 713 controls) donated buccal cell samples. In
addition to the servicemen, a total of 1090 mothers of servicemen were enrolled and 952
(87%) provided a buccal specimen. The DoDSR serum samples have been assayed for levels of
organochlorines pesticides, polychlorinated biphenyl congeners, insulin-like growth factors
and gonadotropins and steroid hormones. DNA isolated from the buccal cell specimens have
thus far been genotyped for polymorphysms in the hormone metabolism and immune function
pathway, immune function pathway, insulin-like growth factor pathway and for single
nucleotide polymorphisms in the 8q24 locus. In addition, a genome-wide association study has
completed. Statistical analyses of the questionnaire data are continuing.