| [ Summary ] |
There have been few epidemiological studies on gastroenteropancreatic neuroendocrine tumors (GEP-NETs) conducted in Japan. The epidemiology of GEP-NETs [pancreatic endocrine tumors (PETs) and gastrointestinal neuroendocrine tumors (GI-NETs)] in Japan was investigated in 2005 using nationwide stratified random sampling. A total of 2,845 individuals received treatment for PETs. The prevalence rate was estimated to be 2.23/100,000 with an annual onset incidence of 1.01/100,000. Nonfunctioning tumors (NF)-PET constituted 47.4 % of those observed, followed by insulinoma (38.2 %) and gastrinoma (7.9 %). Multiple endocrine type 1 neoplasms (MEN-1) were detected in 10 % of PET scans but only in 6.1 % of NF-PET scans. On the other hand, an estimated 4,406 patients received treatment for GI-NETs. Prevalence rates were estimated to be 3.45/100,000 with an annual onset incidence of 2.10/100,000. The locations of GI-NETs varied, foregut, 30.4 % ; midgut, 9.6 % ; and hindgut, 60.0 %. The frequency of complications due to MEN-1 was 1 %. There are large differences in GEP-NET rates in Japan as opposed to Western countries, primarily due to differences in the presence of MEN-1 in NF-PET cases location, symptomatic status, and prevalence of malignancy in GI-NETs. At present, the epidemiologic survey of 2010 is on-going. |