Endocrine Abstracts

Introduction: In multiple endocrine neoplasia 1 (MEN1), the decreased life expectancy is related especially to pancreatic neuroendocrine tumors (panNETs). Timely diagnosis of potentially aggressive panNETs is the cornerstone of the follow-up in MEN1. Somatostatin receptor positron emission tomography (SSTR PET/CT) has a high accuracy in the detection of neuroendocrine tumors. The role of this imaging modality in early diagnosis and follow-up of MEN1-related panNETs is unclear.

Patients and methods: We compared SSTR PET/CT and conventional imaging in 58 patients with MEN1 (median age 40 (range 16–72) years) in Helsinki University Hospital, Helsinki, Finland and in Turku University Hospital, Turku, Finland. SSTR PET/CT was used either as a screening tool in patients without pancreatic NET or in the follow-up of known panNETs. SSTR PET/CT and matched magnetic resonance imaging (88%) or computed tomography (12%) images (median difference between images 3.0 months, IQR 1.2-7.8) were blindly analyzed by two experts. We also assessed the impact of SSTR PET/CT on the management of MEN1 patients during a median follow-up of 46 months.

Results: SSTR PET/CT detected 1.57 (±2.19) more panNETs per patients than conventional imaging. Significantly more lesions were found in the entire pancreas (P<0.001), locating particularly in the head (P<0.001) and in the body-tail (P=0.001) regions. SSTR PET/CT detected lymph node metastases not identified on conventional imaging in four patients (three abdominal and one mediastinal metastases). There was no statistically significant difference in the amount of suspected hepatic lesions (13 vs 23, P=0.54). The SSTR PET/CT changed the management of 27/58 (47%) patients: 7/58 (12%) were referred for surgery, 5/58 (9%) received systemic treatment, and in others the follow-up was intensified. In 15/25 (60%) patients with either no previous panNET (n=22) or in remission after surgery (n=3), SSTR PET/CT identified a panNET (n=14) or recurrence (n=1). In eight patients, SSTR PET/CT revealed a panNET not immediately visible on conventional imaging. During a median follow-up of 47 months, three became visible on conventional imaging, but none required intervention. When SSTR PET/CT was negative, no panNETs were identified on conventional imaging during the 38 months of follow-up.

Conclusions: SSTR PET/CT has high accuracy in the detection of MEN1-related panNETs and changes the disease management in nearly half of the MEN1 patients.