ABSTRACT Objective To compare the long-term medical costs of active surveillance (AS), partial thyroidectomy (PT), and total thyroidectomy (TT) in patients with low-risk papillary thyroid microcarcinoma (PTMC) receiving care covered by the Brazilian Public Health System. Materials and methods After reviewing AS cohorts and our own data, we created a model of AS, PT, and TT flow care for low-risk PTMC over 10, 20, and 30 years. The medical costs included those associated with diagnosis, surgery, and follow-up. We considered that 13.3% of the patients on AS would require surgery after a mean of 21.3 months, 4% undergoing TT would develop permanent hypoparathyroidism, and 43% undergoing PT would develop hypothyroidism. Results The most economical alternative was AS. The costs of TT per patient were higher than those of AS by 182.8% over 10 years (866.89 versus 306.49 US dollars [USD], respectively), by 152.9% over 20 years (1,023.66 versus 404.73 USD, respectively), and by 134.7% over 30 years (1,180.42 versus 502.96 USD, respectively). The costs of PT per patient were higher than those of AS by 16.0% over 10 years (355.66 versus 306.49 USD, respectively), by 16.9% over 20 years (473.41 versus 404.73 USD, respectively), and by 17.5% over 30 years (591.17 versus 502.96 USD, respectively). Conclusion The AS approach was less costly than immediate surgery throughout 30 years of follow-up. Hence, the implementation of AS in Brazil should not be hindered by cost considerations. longterm long term , (AS) (PT) (TT lowrisk low risk (PTMC System data 3 diagnosis followup. followup follow up. up follow-up 133 13 13.3 213 21 21. months 4 hypoparathyroidism 43 hypothyroidism 1828 182 8 182.8 1 866.89 86689 866 89 (866.8 30649 306 49 306.4 USD [USD] respectively, respectively respectively) 1529 152 9 152.9 2 1,023.66 102366 023 66 (1,023.6 40473 404 73 404.7 1347 134 7 134.7 1,180.42 118042 180 42 (1,180.4 50296 502 96 502.9 respectively. . 160 16 0 16.0 355.66 35566 355 (355.6 169 16.9 473.41 47341 473 41 (473.4 175 17 5 17.5 591.17 59117 591 (591.1 Hence considerations (AS (PT 13. 18 182. 866.8 8668 86 (866. 3064 306. [USD 15 152. 1,023.6 10236 02 6 (1,023. 4047 40 404. 134. 1,180.4 11804 (1,180. 5029 50 502. 16. 355.6 3556 35 (355. 473.4 4734 47 (473. 17. 591.1 5911 59 (591. 866. (866 1,023. 1023 (1,023 1,180. 1180 (1,180 355. (355 473. (473 591. (591 (86 1,023 102 (1,02 1,180 118 (1,18 (35 (47 (59 (8 1,02 (1,0 1,18 11 (1,1 (3 (4 (5 ( 1,0 (1, 1,1 1, (1

ABSTRACT Objective: Although thyroid microcarcinoma (TMC) usually has a favorable prognosis, some patients present a higher risk of disease recurrence or persistence. Thus, we aimed at identifying possible risk factors associated with an incomplete response to therapy in TMC. Subjects and methods: This was a retrospective study of 517 patients with TMC treated with total thyroidectomy, with or without radioactive iodine (RAI) therapy, reclassified after 1.1 ± 0.4 years according to the response to treatment into “favorable” (excellent/indeterminate) or “unfavorable” (biochemical/structural incomplete) responses. We evaluated participants' age, sex, tumor size, histological variants, multifocality, presence of vascular/lymphatic/perineural invasion, extrathyroidal extension, metastatic lymph nodes (LN), and distant metastasis. The effect of RAI therapy on the response range was analyzed in a given subgroup. Results: The mean age observed was 46.4 ± 12.0 years, and 89.7% were female. We noted 97.5% with papillary carcinoma, 27.8% with multifocality and 11.2% with LN metastasis. Although the majority of patients had a low risk of recurrence/persistence (78%), 75% were submitted to RAI therapy. Incomplete response (20.7%) was associated with multifocality (p=0.041; OR=1.619) and metastatic LN (p=0.041; OR=1.868). These variables were strongly correlated (p=0.000; OR=3.283). No cut-off of tumor size was identified as a predictor of incomplete response by the receiver operating curve analysis. RAI treatment did not influence the response of patients with multifocality or LN metastasis. Conclusion: Multifocality and LN metastasis are independent risk factors for incomplete response in TMC patients and are strongly correlated. Additional RAI therapy was not associated with a more favorable response in these subgroups.

ABSTRACT Objective: The intermediate-risk (IR) category includes tumors with different degrees of aggression. We aimed to identify the risk factors associated with unfavorable response to initial treatment and compare the effect of low/high radioactive iodine (RAI) therapy. Subjects and methods: A total of 614 IR patients were selected from a database, during 1972-2015. All patients underwent total thyroidectomy and RAI therapy and were reclassified after 12-18 months into the favorable (complete/indeterminate) response group and the unfavorable (biochemical/incomplete structural) response group. A total of 92 patients were assessed for late response (mean: 9.19 ± 5.73 years). Age, gender, tumor size, histology, multifocality, vascular invasion, extrathyroidal extension, presence and number of lymph node metastasis, and stimulated thyroglobulin at ablation (sTg) were evaluated. Results: Mean age at diagnosis was 41.47 ± 15.81 years, and 83.6% of the patients were female. Within 12-18 months after initial therapy, unfavorable response was detected in 41.2% of the patients and was associated, in multivariate analysis, with lymph node metastasis (p = 0.041; odds ratio [OR] = 1.9), presence of more than five metastatic lymph nodes (p = 0,017; OR = 2.6), and sTg > 10 ng/mL (p = 0.005; OR = 10.0). For patients with a longer follow-up, sTg >10 ng/mL was associated with unfavorable response (p = 0.002; OR = 6.8). A higher RAI dose was not related to better prognosis at the end of the follow-up. Conclusion: A sTg level of >10 ng/mL and lymph node metastasis were associated with an unfavorable response 12-18 months after initial treatment. A RAI dose below 150 mCi was proven sufficient to treat IR patients.