Endocrine Abstracts (2017) 49 EP177 | DOI: 10.1530/endoabs.49.EP177

Pancreatic neuroendocrine tumors (PNETs) in patients with MEN1 syndrome

Tatjana Isailovic1, Djuro Macut1, Sanja Ognjanovic1, Milan Petakov1, Valentina Elezovic1, Ivana Milicevic2, Bojana Popovic1, Ivana Bozic Antic1, Tamara Bogavac1, Dusan Ilic1 & Svetozar Damjanovic1

1Clinic for Endocrinology, Department for Endocrine Tumors and Heritable Cancer Syndromes, Belgrade, Serbia; 2Clinic for Endocrinology, Genetic Laboratory, Belgrade, Serbia.

PNETs represent the leading cause of mortality in MEN1 patients. Yet, their characteristics, behaviour, and therefore management, are still uncertain.

The aim of this study was to describe the main clinical characteristics of NETs in MEN1, and to compare them with sporadic NETs.

We investigated 164 patients with PNETs retrospectively, treated in one centre from 2004–2016. We identified 15 (9.1%) patients with MEN1. All patients had germline mutations in MEN1 gene, except one who had sporadic MEN1. There was no gender difference among the groups. No difference in age at onset between the groups was noted (48±16.1 in MEN1 vs 53.8±13.5 years in sporadic, P>0.05). According to WHO classification, well-differentiated tumors were the most frequent in MEN1, in contrast to sporadic PNETs where well-differentiated carcinomas prevailed (P<0,01). Functioning PNETs were more frequent in MEN1 group (60 vs 30%, P<0.05). Among functioning tumors, insulinoma and gastrinoma were the most frequent in both groups (P>0.05). MEN1 patients had multiple tumors more frequently (33.3 vs 5%, P<0.05). Metastatic disease as initial presentation had 17% of MEN1, and 26% of sporadic patients (P>0.05). Surgery was performed in 70% of MEN1, and 92% of sporadic patients. Tumor size did not correlate with the presence of metastases at surgery in any of the groups. Median OS was 149 months (95%CI 71–226) with no difference between the groups (X2=2.049, P>0.05). Mean time to tumor progression (TTP) was estimated to 41 months (95%CI 10–75). However, no difference was found regarding the MEN1 status (X2=0.22, P>0.05). TTP negatively correlated to Ki-67, local invasiveness and stage of the disease in all patients, but not to size or functionality. These data suggest that MEN1 PNETs share similar clinical behaviour as sporadic PNETs. Therefore, close tumor surveillance and early surgery are advocated, irrespective of the tumor size or functionality.