EP124 – Risk factors for biochemical and structural incomplete response in a series of 538 intermediate-risk differentiated thyroid carcinoma patients

•   Bezerra, Angela Maria Leal Barros¹; Ferraz, Carolina¹;Faro, Fernanda¹; Ozorio, Fernanda¹; Scalissi, Nilza Maria¹;Cury, Adriano Namo¹; Marone, Marilia Martins Silveira²; Padovani, Rosalia Prado^1,2 1 Santa Casa de São Paulo, School of Medical Sciences, São Paulo, Brazil 2 Nuclear Medicine Service of Santa Casa de São Paulo, School of Medical Sciences, São Paulo, Brazil   Background/ Purpose: The management of intermediate-risk of recurrence patients has been debated. So, the use of radioactive iodine therapy (RIT) and its activity are controversial. The aim of our study is to identify possible risk factors associated with worse prognosis in intermediate-risk patients and evaluate the impact of different activities of RIT in their outcome. Methods: The study included 538 intermediate-risk differentiated thyroid cancer attended at Santa Casa de São Paulo from 1972 to 2015. Patients were submitted to total thyroidectomy and RIT (100 to 300 mCi). After 12- 24 months of initial treatment, they were reclassified according to the ongoing risk stratification (ATA 2015). Age, gender, tumor size, histology, multifocality, vascular invasion, extrathyroidal extension, lymph node metastasis, RIT activities and serum stimulated thyroglobulin at ablation were evaluated as isolated risk factors. Statistical analysis was made using SPSS 13.0 and qui-square and Mann-Whitney tests. Results: Patients with biochemical/structural incomplete response, were associated with male gender (p= 0,003), tumor size (p=0,031), multifocality (p=0,001), lymph node metastasis (p < 0,001), follicular variant- extensively invasive (p=0,039) and stimulated Tg at ablation > 10ng/ml (p=0,001). The frequency of incomplete structural response was higher in males (p=0.05). There was no different outcome between patients receiving doses lower and greater than 150 mCI. Discussion & Conclusion: Some risk factors are associated with worse prognosis. Possible, patients with this risk factor benefit from more aggressive treatments and closer follow up. Even for adjuvant therapy, activities higher than 150 mCi appear not to be necessary.   References:

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