Endocrine Abstracts

Introduction: Incidental diagnosis of thyroid nodules has increased in recent years, leading to thyroid cancer diagnosis inflation. Nonetheless, mortality rate for thyroid malignancies remains very low, suggesting that its treatment is unlikely to affect the overall prognosis in the majority of cases. Several thyroid imaging scores have been proposed to reduce unnecessary invasive diagnostic procedures. Our aim was to verify the usefulness of the EU-TIRADS score on sparing thyroid nodules cytology.

Methods: We conducted a retrospective and observational study of thyroid nodules submitted to fine-needle aspiration biopsy (FNAB) between January 2016 and October 2021 at our center. Each nodule was classified as whether having an indication for FNAB (group A) or not (group B), according to the EU-TIRADS score. We then compared cytology results between the two groups, using Bethesda diagnostic categories.

Results: FNAB were performed in 1935 thyroid nodules from 1308 patients. Using the EU-TIRADS score, 766 (39.6%) nodules had no cytology indication (group B). Of these, 40.2% (n=308) were EU-TIRADS 2, 35.4% (n=271) EU-TIRADS 3 ≤20 mm, 20.2% (n=155) EU-TIRADS 4 ≤15 mm and 4.2% (n=32) EU-TIRADS 5 ≤10mm. In group B, a suspicious or malignant category was reported only in 7 (0.9%) nodules. Suspicious follicular neoplasm was reported in 13 (1.7%) nodules. Group A presented a higher prevalence of suspicious or malignant categories (2.8% vs 0.9%, P<0.01), a higher prevalence of suspicious follicular neoplasm category (4.1% vs 1.7%, P<0.01) and a higher prevalence of nondiagnostic categories (45.1% vs 36.5%, P<0.01). Notably, nondiagnostic categories were found in 279 (36.5%) of nodules submitted to cytology in group B, leading to repetition of cytology and consequent avoidable visit to the clinic in 63 individuals. Interestingly, when comparing avoidable cytology rate per year, we observed a lower rate in the more recent year (26.8% vs 41.3%, P<0.01), suggesting a greater adherence to the EU-TIRADS system for decision making.

Conclusion: In the context of a common disease, such as thyroid nodules, application of the EU-TIRADS system score can avoid unnecessary cytologies, reducing overdiagnosis and consequent overtreatment.