Archives of Endocrinology and Metabolism (Mar 2021)

Prognostic factors for incomplete response in thyroid microcarcinoma: an analysis of initial response to therapy in 517 patients

  • Fernanda Nascimento Faro,
  • Vivian Roberta Ferreira Simões,
  • Gustavo Piech Ricardo,
  • Cristal Peters Cabral,
  • Karina de Cássia Braga Ribeiro,
  • Nilza Maria Scalissi,
  • Adriano Namo Cury,
  • Marília Martins Marone,
  • Rosália do Prado Padovani,
  • Carolina Ferraz

DOI
https://doi.org/10.20945/2359-3997000000341
Journal volume & issue
Vol. 65, no. 5
pp. 579 – 587

Abstract

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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.

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