Diagnosis and treatment of gastroenteropancreatic neuroendocrine tumors: current data on a prospectively collected, retrospectively analyzed clinical multicenter investigation.

Background: The aim of this prospectively collected, retrospectively analyzed clinical investigation was to describe "unmasked" clinical symptoms and methods of diagnosis, treatment, and short-term follow-up of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) diagnosed during 1 year in Austria.

Methods: In total, 277 patients with GEP-NETs were documented. All tumors were immunhistochemically defined according to recently summarized criteria (World Health Organization, European Neuroendocrine Tumour Society). A standardized questionnaire comprising 50 clinical and biochemical parameters (clinical symptoms, mode of diagnosis, treatment, follow-up) was completed by attending physicians.

Results: The most common initial symptoms were episodes of abdominal pain, diarrhea, weight loss, gastrointestinal bleeding, flushing, and bowel obstruction. Overall, 48.1% of tumors were diagnosed by endoscopy, 43.7% were diagnosed during surgery, 5% were diagnosed by fine-needle aspiration of the primary or metastases, and 2.5% were diagnosed during autopsy; 44.5% of tumors were not suspected clinically and were diagnosed incidentally during various surgical procedures. Overall, 18.7% of tumors were removed endoscopically and 67.6% were removed surgically; 13.7% of patients were followed without interventional treatment. Endoscopic or surgical intervention was curative in 81.4% of patients and palliative in 18.6% of patients. At the time of diagnosis, information on metastasis was available in 83.7% of patients with malignant NETs. Lymph node or distant metastases were documented in 74.7% of patients. In 19.3% of patients, 41 secondary tumors were documented, with 78.0% classified histologically as adenocarcinomas.

Conclusion: This investigation summarizes the clinical presentation and current practice of management of GEP-NETs and thereby extends the understanding and clinical experience.