Impact of TNM® 8th edition on thyroid cancer retrospective staging

Abstract

Introduction: Thyroid carcinoma has a global survival close to 97% in 15 years. The 8th TNM® has recently been proposed, with changes that include an increase in the cut-off age from 45 to 55 years, a change in the role of microscopic extra-thyroidal tumor invasion (which is no longer considered a criterion for the classification of T3 tumors), and the presence of cervical metastases as a criterion for staging. As a result, a large proportion of patients are transferred to earlier stages. Methods: Retrospective descriptive cross-sectional study carried out through analysis of the medical records of patients undergoing thyroidectomy at HC-UFPR from January 2014 to December 2017. Inclusion criteria were patients with a postoperative pathological anatomic diagnosis of well-differentiated thyroid carcinoma (DTC) who underwent primary surgery in the study period. Results: 197 patients underwent thyroidectomy during the period considered, 58 with thyroid neoplasia and 34 with DTC. Eight patients had lymph node metastasis, five (14.70%) as N1a and three (8.83%) as N1b. Of the total sample, six (12.5%) patients presented downstaging from the 7th to the 8th edition of the TNM®. One of the re-staged patients had bone metastasis during follow-up and died during surgery to correct a pathological fracture. Conclusion: In this study sample, the update of the TNM® in its 8th edition resulted in the downstaging of six (12.5%) patients with DTC. A longer follow-up and a larger sample are necessary to correctly assess the impact of this change on patient prognosis.