Epidemiological trends of pancreatic and gastrointestinal neuroendocrine tumors in Japan: a nationwide survey analysis.

BACKGROUND

Although neuroendocrine tumors (NETs) are rare, the number of patients with NET is increasing. However, in Japan, there have been no epidemiological studies on NET since 2005; thus, the prevalence of NET remains unknown.

METHODS

We reported the epidemiology of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) [pancreatic neuroendocrine tumors (PNETs) and gastrointestinal neuroendocrine tumors (GI-NETs)] in Japan in 2005. Here, we conducted the second nationwide survey on patients with GEP-NETs who received treatment in 2010.

RESULTS

A total of 3,379 patients received treatment for PNETs in 2010, representing a 1.2-fold increase in the number of patients from 2005 to 2010. The prevalence was estimated to be 2.69/100,000, with an annual onset incidence of 1.27/100,000 in 2010. Non-functioning tumor (NF)-PNETs comprised 65.5% of cases followed by insulinoma (20.9%) and gastrinoma (8.2%). Interestingly, the number of patients with NF-PNETs increased ~1.8 fold since 2005. A total of 19.9% of patients exhibited distant metastasis at initial diagnosis; 4.3% had complications with multiple endocrine neoplasia type 1 (MEN-1), and only 4.0% had NF-PNETs associated with MEN-1. Meanwhile, an estimated 8,088 patients received treatment for GI-NETs, representing a ~1.8-fold increase since 2005. The prevalence was estimated to be 6.42/100,000, with an annual onset incidence of 3.51/100,000. The locations of GI-NETs varied: foregut, 26.1%; midgut, 3.6%; and hindgut, 70.3%. Distant metastasis and complications with MEN-1 were observed in 6.0 and 0.42% at initial diagnosis, respectively. The frequency of carcinoid syndrome in patients with GI-NETs was 3.2%.

CONCLUSION

We clarified the epidemiological changes in GEP-NETs from 2005 to 2010 in Japan.