Epidemiology of GIST demonstrates some consistent features across geographical regions. Whether the reported extreme differences in incidence reflect real variation in population risk warrants further investigation.

The incidence of colorectal cancer (CRC) increases with age and early onset indicates an increased likelihood for genetic predisposition for this disease. The somatic genetics of tumor development in relation to patient age remains mostly unknown. We have examined the mutation status of five known cancer critical genes in relation to age at diagnosis, and compared the genomic complexity of tumors from young patients without known CRC syndromes with those from elderly patients. Among 181 CRC patients, stratified by microsatellite instability status, DNA sequence changes were identified in KRAS (32%), BRAF (16%), PIK3CA (4%), PTEN (14%) and TP53 (51%). In patients younger than 50 years (n = 45), PIK3CA mutations were not observed and TP53 mutations were more frequent than in the older age groups. The total gene mutation index was lowest in tumors from the youngest patients. In contrast, the genome complexity, assessed as copy number aberrations, was highest in tumors from the youngest patients. A comparable number of tumors from young (<50 years) and old patients (>70 years) was quadruple negative for the four predictive gene markers (KRAS-BRAF-PIK3CA-PTEN); however, 16% of young versus only 1% of the old patients had tumor mutations in PTEN/PIK3CA exclusively. This implies that mutation testing for prediction of EGFR treatment response may be restricted to KRAS and BRAF in elderly (>70 years) patients. Distinct genetic differences found in tumors from young and elderly patients, whom are comparable for known clinical and pathological variables, indicate that young patients have a different genetic risk profile for CRC development than older patients.

BackgroundThe 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.MethodsAll patients diagnosed with GEP‐NEN between January 2003 and December 2013 in a well defined Norwegian population of approximately 350 000 people were included. Age‐ and sex‐adjusted incidence rates were calculated. The current 2010 World Health Organization criteria, European Neuroendocrine Tumour Society classification and International Union Against Cancer (UICC) classification were used.ResultsA 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 100 000 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.ConclusionA high crude incidence of GEP‐NEN, at 5·83 per 100 000 inhabitants, was noted together with a significant increasing trend over time.

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