The Ultracyt Study - is EU-TIRADS Useful in Selecting Nodules for Fine Needle Aspiration Cytology? (Ultracyt)

Selective Ultrasound Guided Cytology Using EU-TIRADS Versus Non-selective Ultrasound Guided Cytology for Diagnosing Thyroid Cancer

This is a randomized study evaluating selective fine-needle aspiration cytology based on structured ultrasound using EU-TIRADS versus non-selective ultrasound guided cytology. Primary outcome is frequency of suspicious cytology (Bethesda III-VI) which is expected to be higher in the selective group compared to the non-selective group. Secondary outcome is the frequency of malignancy which is expected to be equal in both groups. However, the investigators do not expect to reach statistical significance for the secondary outcome according to power calculations.

Thyroid nodules are common in the population, and the reported incidence of thyroid cancer is increasing in most parts of the world. Palpable thyroid nodules are reported in 4-5 per cent of the population, of which 5-10 per cent are malignant. The reported incidence of thyroid nodules on ultrasound is higher. EU-TIRADS has been shown in retrospective cohort studies to accurately stratify thyroid nodules with respect to risk of thyroid cancer. EU-TIRADS has been used in Western Sweden since 2017 and in 2021 it was implemented in the Swedish National Guidelines for thyroid cancer. To the knowledge of the investigators, no randomized controlled study has been carried out validating EU-TIRADS. This multicenter regional study aims to investigate the safety of using selective cytology using EU-TIRADS. Primary outcome is the result of cytology suspicious of thyroid cancer. In the selective group, low risk nodules will not undergo cytology and therefore the frequency of cytologically suspicious nodules (Bethesda III-VI) is expected to be higher in this group.

All thyroid nodules are evaluated according to EU-TIRADS and cytology is performed according to EU-TIRADS criteria.

All thyroid nodules are evaluated according to EU-TIRADS and cytology is performed on all nodules >1 cm. Cytology will also be performed on EU-TIRADS 5-nodules measuring between 0.5 and 1 cm.

All noduleas are evaluated according to EU-TIRADS. Cytology performed on all nodules larger than 1 cm regardless of ultrasonographic features. Nodules 1 cm or smaller evaluated as EU-TIRADS 5 undergo cytologic examination if possible.

Fewer nodules in the selective cytology group will most likely undergo fine needle aspiration cytology (FNAC). However, since ultrasonographically benign nodules will not undergo FNAC the frequency of Bethesda III-VI is expected to be higher in the selective cytology group.

The frequency of malignancy is expected to be similar in both groups. Only patients undergoing surgery will be included in this analysis. The investigators do not expect to find statistical significance according to power calculations.

Inclusion Criteria: Patients referred to ultrasonography of the thyroid due to goiter symtoms or positive findings on FDG-PET Exclusion Criteria: Patients previously examined with ultrasonography of the thyroid Patients who have previously undergone thyroid surgery

All IPD will be made available including data, study protocol, statistical analysis plan and informed consent form.

Upon reasonable request data from the study will be made available by email to dr Jakob Dahlberg (jakob.dahlberg@vgregion.se) or dr Andreas Muth (andreas.muth@vgregion.se).

Russ G, Bonnema SJ, Erdogan MF, Durante C, Ngu R, Leenhardt L. European Thyroid Association Guidelines for Ultrasound Malignancy Risk Stratification of Thyroid Nodules in Adults: The EU-TIRADS. Eur Thyroid J. 2017 Sep;6(5):225-237. doi: 10.1159/000478927. Epub 2017 Aug 8.

Cibas ES, Ali SZ. The 2017 Bethesda System for Reporting Thyroid Cytopathology. Thyroid. 2017 Nov;27(11):1341-1346. doi: 10.1089/thy.2017.0500.