Primary small intestinal neuroendocrine tumors are highly prevalent and often multiple before metastatic disease develops.

BACKGROUND: Small intestinal neuroendocrine tumors are the most common of small bowel malignancies with a clinical incidence of about 1 per 100,000 persons per year. There has been a threefold increase in the incidence of small intestinal neuroendocrine tumor during later decades, but there are no studies that clarify whether this is due to a true higher incidence or if the rise is a mere product of, for instance, improved diagnostic modalities. The aim of this study was to investigate the incidence of clinical as well as subclinical small intestinal neuroendocrine tumors found at autopsy as well as describing the frequency of concomitant malignancies in patients with small intestinal neuroendocrine tumor. MATERIALS AND METHODS: An autopsy registry from the Malmö county population from 1970 to 1982 with an 87% autopsy rate was used. The clinical autopsy reports for patients coded for the existence of "carcinoid tumor" were scrutinized for the presence of small intestinal neuroendocrine tumor, metastatic disease, and concomitant malignancies. Details of patients with clinically diagnosed small intestinal neuroendocrine tumor during this time period were gathered from the Swedish Cancer Registry. RESULTS: The mean annual incidence of small intestinal neuroendocrine tumor during this period was 5.33 per 100,000 individuals, and the mean annual prevalence was 581 per 100,000. The cause of death in the majority of cases was not due to small intestinal neuroendocrine tumor. In total, 48% of the people with small intestinal neuroendocrine tumor had at least one other malignancy, most commonly colorectal cancer. CONCLUSION: Most small intestinal neuroendocrine tumors are subclinical, and persons living with them will often die due to other causes. There was a high rate of multiple primary tumors (40%), suggesting that multiple tumors seem to arise before the advent of metastatic disease. Moreover, a comparably high rate of associated colorectal carcinoma was found.

Prognostic factors for death after surgery for small intestinal neuroendocrine tumours.

BACKGROUND: Neuroendocrine tumours of the small intestine (SI-NETs) are rare gastrointestinal neoplasms with an annual incidence of about one per 100 000. Patients with apparently similar tumours have variable outcomes. The aim of this study was to identify postoperative prognostic factors identifiable after initial surgery. METHODS: This was a nested case-control study of patients with SI-NETs who were treated between 1961 and 2001. Data were retrieved from the Swedish Cancer Registry. Patients who died from the SI-NET and corresponding controls (who outlived cases by at least 1 month), matched by age at diagnosis and calendar period, were included. Sex, postoperative symptoms, postoperative 5-hydroxyindoleacetic acid (5-HIAA) values, European Neuroendocrine Tumor Society (ENETS) stage, insufficiency of the tricuspid valve, radical secondary surgery and secondary malignancy were studied as potential prognostic factors. RESULTS: In total, 1122 patients were included (561 cases, 561 controls). Postoperative factors of prognostic importance included hormone-related symptoms, stage IV disease, raised levels of 5-HIAA, insufficiency of the tricuspid valve, secondary surgery not being macroscopically radical and a second malignancy. CONCLUSION: Stage and symptomatic disease are important prognostic factors in SI-NET.