**5. Conclusions**

In conclusion, early treatment response in patients with classical or follicular variants of T1/T2 PTC is not significantly affected by the presence of mETE. Despite a higher incidence of lymph node metastases in patients with mETE, prophylactic lymphadenectomy is not suggested in patients in the T1/T2-stage. Therefore, accurate perioperative patient workup, including cervical neck ultrasound and post-treatment WBS, remains crucial.

**Author Contributions:** Authors contributed equally to this work; F.A., V.W.; conceptualization, A.T., F.A., D.W.; writing—original draft preparation, F.A., V.W.; supervision, A.T., H.I., C.S., S.L., P.B., M.U., T.K.; writing—review and editing, A.T., P.B., H.I.; visualization, F.A., M.U.; project administration, P.B., A.T., F.A.; data curation, F.A., D.W.; resources, F.A., D.W. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was financially supported by the Kuhbier-Langewiesche foundation and the Bavarian Equal Opportunities Sponsorship (BGF). The foundation had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No other potential conflicts of interest relevant to this article exist.

**Acknowledgments:** A significant part of this work originated from the doctoral thesis of Daniel Wacker. Vera Wenter was financially supported by the Bavarian Equal Opportunities Sponsorship (BGF) to promote equal opportunities for women in research and teaching. The sponsorship did not influence study design, data collection and analysis, decision to publish, or preparation of the manuscript.

**Conflicts of Interest:** The authors declare that they have no conflict of interest.
