Correlating the Bethesda System for Reporting Thyroid Cytopathology with Histology and Extent of Surgery: A Review of 21,746 Patients from Four Endocrine Surgery Registries Across Two Continents

BackgroundThe Bethesda system for cytopathology (TBSRTC) is a 6-tier diagnostic framework developed to standardize thyroid cytopathology reporting. The aim of this study was to determine the risk of malignancy (ROM) for each Bethesda category.MethodsThyroidectomy-related data from 314 facilities in 22 countries were entered into the following outcome registries: CESQIP (North America), Eurocrine (Europe), SQRTPA (Sweden) and UKRETS (UK). Demographic, cytological, pathologic and extent of surgery data were mapped into one dataset and analyzed.ResultsOut of 41,294 thyroidectomy patient entries from January 1, 2015, to June 30, 2017, 21,746 patients underwent both thyroid FNA and surgery. A comparison of cytology and surgical pathology data demonstrated a ROM for Bethesda categories 1 to 6 of 19.2%, 12.7%, 31.9%, 31.4%, 77.8% and 96.0%, respectively. Male patients had a higher rate of malignancy for every Bethesda category. Secondary analysis demonstrated a high ROM in male patients with Bethesda 3 category aged 31-35 years (52.1%, 95% confidence interval (CI) 37.9-66.2%), aged 36-40 years (55.9%, 95% CI 39.2-72.6%) and aged 41-45 years (46.9%, 95% CI 33-60.9%). Patients with Bethesda 5 and 6 scores were more likely to undergo total thyroidectomy (65.9% and 84.6%); for patients with Bethesda scores 2 and 3, a higher percentage of females underwent total thyroidectomy compared to males in spite of a higher ROM for males.ConclusionsThese data demonstrate that Bethesda categories 1-4 are associated with a higher ROM compared to the first edition of TBSRTC, especially in male patients, and validate findings from the second edition of TBSRTC.