Pancreatic Endocrine Tumors and GIST - Clinical Markers, Epidemiology and Treatment

Sammanfattning: Pancreatic endocrine tumors and gastrointestinal stromal tumors are rare. Evidence regarding prognostic factors, and in the former also treatment, is scarce.We evaluated the survival and prognostic factors in a consecutive series of 324 patients with pancreatic endocrine tumors treated at a single institution. Radical surgery, WHO classification, TNM stage, age and Ki67 ?2% emerged as independent prognostic factors. Having a non-functioning tumor was not an independent prognostic marker, and neither was hereditary tumor disease. We present the first evaluation of the newly proposed TNM staging system for these patients. A separate analysis of well-differentiated neuroendocrine carcinomas is reported, suggesting tumor size ?5cm and Ki67 ?2% as negative prognostic markers in this group.The first 36 patients with advanced neuroendocrine tumors treated with temozolomide at our clinic were evaluated. The median time to progression was seven months. Fourteen percent showed partial regression and 53% stabilization of disease. Side effects were generally mild. Investigation of O6-methylguanine DNA methyltransferase revealed a low expression in a subset of tumors. Four out of five patients responding to treatment had tumors with low expression.Concomitant expression of the orexigen ghrelin and its receptor in pancreatic endocrine tumors is demonstrated. No significant difference in mean plasma ghrelin between patients and controls were found, but elevated plasma ghrelin was seen in five patients.We provide the first report of expression of ghrelin and its receptor in gastrointestinal stromal tumors. Concomitant expression was frequent, indicating the presence of an autocrine loop. The tumors also expressed the neuroendocrine marker synaptic vesicle protein 2. Together, these findings are suggestive of neuroendocrine features.