Epidemiology and classification of gastroenteropancreatic neuroendocrine neoplasms using current coding criteria

Abstract

Background: The lack of uniform criteria for coding of gastroenteropancreatic neuroendocrine neoplasia (GEP-NEN) has hampered previous epidemiological studies. The epidemiology of GEP-NEN was investigated in this study using currently available criteria. Methods: All patients diagnosed with GEP-NEN between January 2003 and December 2013 in a well defined Norwegian population of approximately 350000 people were included. Age- and sex-adjusted incidence rates were calculated. The current 2010 World Health Organization criteria, European Neuro- endocrine Tumour Society classification and International Union Against Cancer (UICC) classification were used. Results: A total of 204 patients (114 male, 55 ⋅ 9 per cent) were identified. The median age at diagnosis was 61 (range 10–94) years. The annual overall crude incidence was 5⋅83 per 100000 inhabitants, with an increasing trend (P=0⋅033). The most frequent location was small intestine (60 patients, 29⋅4 per cent) followed by appendix (48 patients, 23⋅5 per cent) and pancreas (33 patients, 16⋅2 per cent). Grade 1 tumours were more common in gastrointestinal (100 patients, 58⋅5 per cent) than in pancreatic (9 patients, 27 per cent) NEN. According to the UICC classification, 77 patients (37⋅7 per cent) had stage I, 17 patients (8⋅3 per cent) stage II, 37 patients (18⋅1 per cent) stage III and 70 patients (34⋅3 per cent) had stage IV disease. No patient with stage I disease had grade 3 tumours; advanced tumour grade increased with stage. Conclusion: A high crude incidence of GEP-NEN, at 5⋅83 per 100000 inhabitants, was noted together with a significant increasing trend over time,