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BACKGROUND: Positron emission tomography/computed tomography with fluorodeoxyglucose (F-18) (FDG PET/CT) is increasingly used in Kaposi sarcoma (KS), but its value has not been assessed. OBJECTIVES: In this study, we aimed to evaluate the diagnostic accuracy of FDG PET/CT to define the extent of disease in KS. METHODS: Consecutive patients with KS referred to our department for FDG PET/CT were included. The diagnostic accuracy of FDG PET/CT for cutaneous and extra-cutaneous KS staging was assessed on a per lesion basis compared to staging obtained from clinical examination, standard imaging, endoscopy, histological analyses, and follow-up. RESULTS: From 2007 to 2017, 75 patients with FDG PET/CT were analyzed. The sensitivity and specificity of FDG PET/CT for the overall detection of KS lesions were 71 and 98%, respectively. Sensitivity and specificity were 100 and 85% for lymph nodes, 87 and 98% for bone, 87 and 100% for lungs, and 100 and 100% for muscle involvement, whereas sensitivity was only 17% to detect KS digestive involvement. The sensitivity of the diagnostic for KS cutaneous involvement increased from 73 to 88% when using a whole-body examination. CONCLUSION: FDG PET/CT showed good sensitivity and specificity for KS staging (digestive involvement excepted) and could be used for staging patients with active KS.
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OBJECTIVES: Bone metastases (BM) may influence negatively the prognosis of midgut neuroendocrine tumors (NET). The diagnostic sensitivity of 18F-DOPA PET for midgut NET and associated metastases is high. This study aimed to assess the prognostic impact of BM detected by 18F-DOPA PET in metastatic midgut NET. METHODS: All patients with a metastatic midgut NET, who underwent a 18F-DOPA PET between June 2011 and June 2018, were included. BM were defined following imaging criteria and were classified as poly-BM or oligo-BM, according to their number (< 5 or ≥ 5, respectively). The variables associated with the presence of BM were evaluated by logistic regression. The factors associated with overall survival were explored by Cox regression models. RESULTS: Among 155 patients included, 46 had BM (29.7%). A carcinoid syndrome (OR 2.96, p = 0.009) and ≥ 3 extra-skeletal metastatic organs (OR 4.99, p = 0.002) were independently associated with the presence of BM. BM were mainly osteoblastic (78%), rarely symptomatic (8.9%), and had a short-term therapeutic impact for 3 patients (6.5%). The presence of BM (HR 2.67, p = 0.034), older age (HR 1.07, p = 0.016), and higher Ki67 (HR 1.09, p = 0.025) were independent prognostic factors. Unlike poly-BM (HR 1.92, p = 0.007), oligo-BM was not a poor prognosis factor (HR 0.77, p = 0.699) compared to the group without BM. CONCLUSION: 18F-DOPA PET frequently detects BM in patients with metastatic midgut NET. BM have a negative prognostic impact, especially poly-BM. Conversely, oligo-BM do not influence the prognosis and may not impact therapeutic decisions. KEY POINTS: ⢠18F-DOPA PET detected bone metastases in 46 (29.7%) of 155 patients with metastatic midgut neuroendocrine tumors. ⢠Bone metastases have a negative prognostic impact in metastatic midgut neuroendocrine tumors. ⢠Bone oligo-metastases (< 5) do not influence the prognosis and may not impact therapeutic decisions.
