Micropapillary thyroid carcinoma: not so harmless as it seems. A 5-year follow-up cohort retrospective study.

Abstract

Introduction: Differentiated thyroid cancer is becoming increasingly prevalentmostly due to the increasing incidence of micropapillary carcinoma. For low-risktumors, hemithyroidectomy does not reduce survival and may be associated withhigher local recurrence. This study aimed to compare Micropapillary versusPapillary thyroid carcinomas regarding overall survival and disease-free survival.Methods: A retrospective, unicentric, cohort study was carried between 2012 and2016. Consecutive cases with (micro)papillary thyroid carcinoma were enrolledand divided in microcarcinoma group and control group. Exclusion criteria wereloss to follow-up, previous thyroid surgery and non-operative treatment. Acomparison of several clinical and pathological parameters, recurrence rate andcumulative survival was performed between groups. Results: Patients withmicropapillary carcinomas were younger and frequently asymptomatic. 6.5% ofthese carcinomas presented a benign cytology (Bethesda II) in this study. 18.9% ofthese patients were submitted to hemithyroidectomy but 71.4% were thereaftertotalized. Micropapillary carcinomas presented higher rate of multifocality butsimilar lymph node invasion rate, lymph node dissection rate and adjuvant iodinetherapy. Patients with micropapillary carcinomas presented less advanced stagingbut similar recurrence rate and time to recurrence; moreover, higher stage wasonly related with (older) age of presentation. Conclusions: In this studymicropapillary carcinomas presented better staging but similar recurrence ratecomparing with papillary carcinomas. Moreover, most of these patients weresubmitted to totalization. These results question if hemithyroidectomy is still agood option for micropapillary carcinomas and if this staging system is adequate.Larger studies with longer follow-up are needed to confirm or refute these results.