METHODS
A retrospective multicenter cohort study of patients who underwent thyroid surgery at two tertiary care academic hospitals from January 1, 2016 to December 1, 2019 was performed. Consecutive patients with a dominant thyroid nodule who underwent both USFNA and molecular profile testing (ThyGeNEXT, Interpace Diagnostics, Parsippany, NJ, USA or ThyroSeq v3, UPMC, Pittsburgh, PA, USA) followed by thyroidectomy were included in the study. Indications for molecular profile testing of thyroid nodules was for cytologically indeterminate Bethesda category (III, IV, V) or discordance cytology results with ultrasound findings. Patients who did not undergo thyroidectomy as well as pediatric patients were excluded from the study. This study was approved by the Research Ethics Committee at the tertiary care center (REB 2019-1532).
Clinical data including age, sex, Bethesda category of the dominant nodule, and if a molecular mutation was identified were collected. In addition, the extent of thyroidectomy performed (hemi, total or completion thyroidectomy) and postoperative histopathology were noted. Postoperative histopathology was classified as benign disease, malignant or non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Furthermore, PTC of less than 10mm were classified as microcarcinomas. Additionally, aggressive thyroid cancer was defined as any evidence of thyroid carcinoma variants (tall cell, hobnail, solid, diffuse sclerosing, anaplastic or poorly differentiated), clinical evidence of extrathyroidal extension or central neck metastasis.
The STROBE guidelines were used for reporting data. Descriptive statistics to characterize the cohort was performed. The association between Bethesda category and type of molecular mutation of dominant thyroid nodule on USFNA was compared using Chi-square testing. Logistic regression was performed to quantify the measure of association between Bethesda category and type of molecular mutation of the dominant thyroid nodule. Also, comparison of Bethesda category and molecular mutation to postoperative pathology was performed using Chi-square testing.