To Örebro University

Introduction: The prevalence of bone metastases (BM) in small intestinal neuroendocrine tumors (Si-NET) ranges from 5 to 23 %.

Aim(s): The aim of our study was to evaluate the overall survival (OS) and the associated symptoms, in particular bone-related pain and fractures in Si-NET patients with BM, which previously have been sparsely described. 

Materials and methods: This is a retrospective cohort study between 1st of January 2010 and 20th of March 2023. We included 133 Si-NET patients with BM detected at 68Gallium-DOTATOC-octreotate PET/CT (68Ga-SSA-PET/CT). Patients were treated and followed at a tertiary referral hospital in Sweden, Uppsala University Hospital. Patients’ characteristics were collected including data on BM-related symptoms, fractures and treatment with analgetics due to bone-related pain. Patients were divided into two groups, those with 1-5 BM or > 5 BM.

Results: We included 133 patients, 64 were women (48%), 74 (56 %) had < 5 BM while 59 (44%) had > 5 BM. Synchronous BM were encountered in 54 patients (41%) at NET diagnosis. Eighteen patients were treated for BM related pain and two had a fracture related to SI-NET BM. Five-year OS was 42 % (median OS 38 months, range 1-209 months). The OS of patients with >5 BM was shorter compared to that of patients with ≤5 BM (5-year OS 21 % vs 58%; p-=0.028) at univariable log-rank analysis. Concurrent carcinoid heart disease was present in 29 Si-NET patients with BM (22%) and was more frequently found in those with > 10 BM (40%).

Conclusion: The number of BM seems to affect OS, as presence of > 5 BM is associated with shorter OS. More extensive bone tumor burden with >10 BM, isl inked with the presence of carcinoid heart disease. Fractures are rare and bone-related pain treatment is needed in up to 14 % of patients.