Epidemiological study of gastroenteropancreatic neuroendocrine tumors in Japan

Tetsuhide Ito, Hironobu Sasano, Masao Tanaka, R. Yoshiyuki Osamura, Iwao Sasaki, Wataru Kimura, Koji Takano, Takao Obara, Miyuki Ishibashi, Kazuwa Nakao, Ryuichiro Doi, Akira Shimatsu, Toshirou Nishida, Izumi Komoto, Yukio Hirata, Kazuhiko Nakamura, Hisato Igarashi, Robert T. Jensen, Bertram Wiedenmann, Masayuki Imamura

Research output: Contribution to journalArticlepeer-review

306 Citations (Scopus)


Background: There have been few epidemiological studies on gastroenteropancreatic neuroendocrine tumors (GEP-NETs) in Japan. Methods: We examined the epidemiology of GEP-NETs [pancreatic endocrine tumors (PETs) and gastrointestinal neuroendocrine tumors (GI-NETs)] in Japan in 2005 using a nationwide stratified random sampling method. Results: A total of 2,845 individuals received treatment for PETs. Prevalence was estimated as 2.23/100,000 with an annual onset incidence of 1.01/100,000. Non-functioning tumor (NF)-PET constituted 47.4%, followed by insulinoma (38.2%) and gastrinoma (7.9%). Distant metastases were reported in 21% patients with NF-PETs and occurred more frequently as tumor size increased (>2 cm). Multiple endocrine neoplasia type 1 (MEN-1) was detected in 10% of PETs but only in 6.1% of NF-PETs. NF-PETs were detected incidentally by physical examination in 24% patients. In 2005, an estimated 4,406 patients received treatment for GI-NETs. Prevalence was estimated as 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%. Distant metastases were observed in 6%. Lymph node metastases occurred more frequently as tumor size increased (>1 cm). The frequency of MEN-1 complications was 1%. Physical examination revealed GI-NETs in 44% patients. The frequency of symptomatic GI-NETs was 3.4%. Interestingly, 77.1% of patients with foregut GI-NETs had type A gastritis. Conclusion: Our results show there are large differences in GEP-NETs between Japan and Western nations, primarily due to differences in the presence of MEN-1 in NF-PETs and the location, symptomatic status, and prevalence of malignancy in GI-NETs.

Original languageEnglish
Pages (from-to)234-243
Number of pages10
JournalJournal of gastroenterology
Issue number2
Publication statusPublished - Feb 2010

All Science Journal Classification (ASJC) codes

  • Gastroenterology


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