Gastroenteropancreatic neuroendocrine tumors in Iceland: a population-based study.

OBJECTIVE

To determine the incidence, distribution, and prognosis of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) over the last 30 years and analyze changes over time.

METHODS

All patients diagnosed with GEP-NETs in Iceland from 1985 to 2014 were identified through the Icelandic Cancer Registry and pathology laboratory records. Relevant clinical information was obtained from medical records. In order to assess trends, the study period was divided into two periods, 1985-1999 and 2000-2014.

RESULTS

A total of 364 patients with GEP-NETs were identified. Overall, 18 patients diagnosed at autopsy or with primary tumors of an unknown site were excluded, leaving 346 patients with 351 primary tumors for final analysis. The overall mean annual incidence 1985-2014 was 3.65/100,000, 3.39/100,000 during 1985-1999 and 3.85/100,000 during 2000-2014 (p = NS). The most common primary tumor site was the appendix (32%), followed by the jejunum/ileum (24%) and stomach (17%). In all, 18% of patients presented with distant metastases at the time of diagnosis, most noticeably patients with primary tumors of the colon (47%), pancreas (46%) and jejunum/ileum (39%). The most favorable 5-year survival was observed for tumors of the appendix (94%) and rectum (88%) and the least favorable for tumors of the pancreas (31%), colon (47%) and jejunum/ileum (66%). There were no statistically significant changes in incidence, staging or survival between the two time periods.

CONCLUSIONS

In this population-based study, the incidence of GEP-NETs has not changed significantly over the last decades. The incidence of metastatic disease has remained stable and overall prognosis has not improved in recent years.