Racial disparities in the anatomic distribution of gastrointestinal neuroendocrine tumors

Neuroendocrine tumors (NETs) are a rare type of malignancy, however, their incidence and prevalence have markedly increased over the past several decades. Gastroenteropancreatic neuroendocrine tumors (GEP-NETs), NETs of the gastrointestinal (GI) tract, account for the majority of these tumors. Data from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute (NCI), as well as from multiple cancer registries in Canada and Europe, indicate that the small intestine is one of the most common primary sites of GEP-NET development in Caucasian populations. Smaller studies from Asian countries, however, report a significantly lower proportion of small intestinal NETs (SI-NETs) in those countries’ populations. Interestingly, this finding persists in a study of Asians living in the United States, which, therefore, may suggest that genetics, and not environment, play a predominant role in driving this difference. Multiple studies exploring the genetics of SI-NETs in Caucasians have been published and have identified several genetic alterations implicated in tumorigenesis. However, the most consistently reported finding is chromosome 18 loss of heterozygosity (chr18 LOH), which has been detected in 61-78% of SI-NETs. Unfortunately, these studies have yet to be performed in a strictly Asian cohort. The proposed study, therefore, is a multicenter, cross-sectional study that will compare the proportion of SI-NETs with chr18 LOH in Asian versus Caucasian populations by performing a fluorescence in-situ hybridization (FISH) analysis of SI-NET tissue from both Asian and Caucasian samples. Overall, the results of this study may help to identify possible mechanisms driving the difference in proportion of SI-NETs between Asians and Caucasians, which in turn, may help to better characterize the genetic events leading into SI-NET tumorigenesis