Endocrine Abstracts

JOINT494

Introduction: In patients with multiple endocrine neoplasia type 1 (MEN1) followed up at ENETS centers of Excellence, chromogranin A (CgA) and pancreatic polypeptide (PP) are widely used screening tools for pancreatic neuroendocrine tumours (panNETs). However, previous studies demonstrated conflicting results regarding their performance in MEN1 and the follow-up protocol can be questioned. This study aims to bring clarity to the question by investigating a well-characterized MEN1 cohort that, in addition to biomarker screening, underwent both somatostatin receptor positron emission tomography/computed tomography (SSTR PET/CT) and conventional imaging for the detection of panNETs. We studied the impact of long-term biomarker follow-up on the clinical management of panNETs in MEN1.

Methods: The study cohort consisted of 58 MEN1 patients from a European reference center for rare endocrine condition, all of whom underwent both SSTR PET/CT and conventional imaging of the pancreas in addition to long-term biomarker screening. We calculated sensitivity and specificity of CgA and PP for diagnosing any panNET, panNETs ≥ 20 mm, and metastatic panNETs, with pancreatic imaging as the reference standard. The longitudinal impact of 10-year annual biomarker measurements on clinical management was analyzed from electronic patient records.

Results: The sensitivity of CgA for diagnosing any panNET, ≥ 20 mm panNET, and metastatic panNET was 35%, 30%, and 60%, respectively. The sensitivity of PP for the same categories was 23%, 33%, and 0%, respectively. The area under the curve (AUC) in receiver operator characteristics analysis for CgA was 0. 30 (95% CI 0. 09-0. 51) for any panNET, 0. 49 (95% CI 0. 09-0. 51) for ≥ 20 mm panNET, and 0. 69 (95% CI 0. 42-0. 95) for metastatic panNET. The AUC for PP in detecting metastatic panNETs was 0. 28 (95% CI 0. 11-0. 46). Biomarker performance was poor and did not detect any new panNETs, or clinically significant panNETs (tumours > 20 mm in size). Annual biomarker measurements during 514 patient-years of follow-up did not affect the clinical management of panNETs.

Conclusion: CgA and PP are not helpful in diagnosing panNETs in patients with MEN1. Long-term biomarker measurements did not impact clinical management of panNETs. The findings question the clinical value of using CgA and PP for the screening of panNETs in MEN1. Practice should change and other diagnostic methods prioritized instead.