Endocrine Abstracts

Background: Neuroendocrine tumours (NET) can affect various tissues and organs, have different clinical presentation and prognosis, depending on the primary tumour site, grading, differentiation and functional status. Reported prevalence of bone metastases (BM) from NETs has been increasing with improved imaging modalities, reaching >40% in some reports. The BM diagnosis is associated with reduced overall survival; however, this was not confirmed by all studies.

Methods: We performed a retrospective single centre analysis of patients with pancreatic (pNET) and small intestinal (siNET) primaries (n=377) and identified 40 patients diagnosed with BM (19 with pNET, 21 with siNET). The scans were assessed by an independent radiologist blinded to the primary site diagnosis and to the history. IBM SPSS-24 was used to compare overall survival. The survival was calculated based on ‘alive’ status as per 1^st December 2017. Statistical significance was accepted at P<0.05.

Results: The prevalence of BM was 10% for pNET and 11.2% for siNET; BM were present at the time of diagnosis in 23 patients (57.5%), including 68.4% pNET patients who developed BM at some point in their disease course, as opposed to 47.6% siNET, P=0.249. Nine patients had lytic, 24 sclerotic and 3 mixed bone lesions. Data regarding fractures was available in 33 patients, 4 of them had fractures identified, however only 2 had fractures related to the BM, in both of them tumours originating from pancreas. Almost half of pNET patients who developed BM had grade 3 tumours, as opposed to only about 10% of siNET. We observed a significantly higher prevalence of lytic lesions in pNET as compared to siNET. Interestingly, 2/3 of pNET with lytic BM were grade 3 tumours vs grade 1 for siNET. Overall survival (OS) was better for siNET in our analysed cohort of patients, having a longer survival since the time of diagnosis of NET (P=0.034); the difference in survival post diagnosis of BM was not statistically significant. The median OS for the whole cohort of pNET and siNET since the time of detection of BM ranged from 12 months in G3 pNET to 58 months in G2 siNET. The sclerotic BM were associated with more favourable prognosis; however, the difference did not reach the statistical significance.

Conclusions: A substantial proportion of NET patients with BM have skeletal lesions at the time of initial diagnosis of NET. BM from pNET are associated with higher grade primaries, lytic lesions and shorter OS.