ECE2015 Guided Posters Thyroid – diagnosis (9 abstracts)
Low/undetectable pre-ablation thyroglobulin in well-differentiated thyroid cancer patients with positive post-ablative 131I whole body scans: causes and consequences
Daniela Guelho 1 , Fernando Albán 2 , Miguel Melo 1 , Cristina Ribeiro 1 , Isabel Paiva 1 , Carolina Moreno 1 , Nuno Vicente 1 , Luis Cardoso 1 , Diana Martins 1 , Diana Oliveira 1 , Margarida Balsa 3 , Gracinda Costa 2 & Francisco Carrilho 1
1Endocrinology, Diabetes and Metabolism Department, Coimbra Hospital and University Centre, Coimbra, Portugal; 2Nuclear Medicine Department, Coimbra Hospital and University Centre, Coimbra, Portugal; 3Endocrinology, Diabetes and Nutrition Department, Baixo Vouga Hospital Centre, Aveiro, Portugal.
Introduction: In patients with well-differentiated thyroid cancer (DTC) low/undetectable thyroglobulin (Tg) at time of remnant ablation usually reflects a complete previous surgery. However, in a small percentage (6.3–16%) it can represent false negative values.
Objectives: Evaluate the frequency of patients with low/undectable Tg at time of remnant ablation with locoregional or distant lesions at post-ablative 131I whole body scan (WBS) and the influence of Tg levels in long-term outcome.
Methods: Retrospective analysis of all patients with DTC submitted to ablative 131I treatment in our centre. Included: patients with a stimulated Tg <5 ng/ml (measured at time of remnant ablation) and locoregional or distant uptake at post-ablative 131I WBS, performed 6–7 days after. Excluded: patients with TSH <30 mUI/ml after thyroid hormone withdrawal or with a follow-up <6 months. Statistical analysis: SPSS (21).
Results: Of 967 patients, 211 (21.8%) were included (178♀; 33♂). Ninety-two (43.6%) presented anti-Tg antibodies. Only patients with negative anti-Tg antibodies (n=119) were considered at subsequent analysis. In those, Tg was lower if lymphocytic infiltrate (P<0.05) or abundant solid areas (P<0.05) present at histopathological evaluation. Post-ablative 131I WBS showed thyroid bed (73.3%), laterocervical (5.9% unilateral and 16.8% bilateral), supraclavicular (0.8%), mediastinal (1.6%), and pulmonar (1.6%) uptake. During a follow-up of 8±4.8 years, 17 (14.3%) patients showed persistence/recurrence of the disease: eight local and nine distant. The probability of persistence/recurrence was significantly higher if lymph node metastasis (OR=11.8; P<0.01) or extrathyroid uptake at post-ablative 131I WBS (OR=20.8; P<0.01). Disease-free survival was inversely correlated with Tg (ρ=−0.59; P<0.01), being significantly higher in patients presenting undectable Tg (P<0.05).
Conclusion: A fifth of DTC patients presented low/undectable Tg at time of remnant ablation with uptake (locoregional or distant) at post-ablative 131I WBS. In about half was justified by anti-Tg antibodies. In the others, may be related to the presence of microscopic lesions or specific histopathological features. In these patients, low/undectable Tg did not exclude risk of persistence/recurrence, but it seems related with disease-free survival. This study also highlights the importance of post-ablative 131I WBS in the evaluation of these patients.
Volume 37
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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