Predicting risk of malignancy in patients with indeterminate thyroid nodules
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Thyroid cancer is the most prevalent endocrine cancer (1). The prevalence of palpable thyroid nodules in the general adult population is 4% to 7% (2). Ultrasound imaging detects thyroid nodules in 19%-68% of randomly selected individuals (3). The rate of thyroid cancer in nodules found on US is 4% to 15% (4). In order to evaluate thyroid nodules patients undergo thyroid ultrasonography and, if needed, a fine-needle aspiration biopsy. Of all fine-needle aspiration biopsies, 15-30% are indeterminate on cytology (5). While only 3% of these nodules are malignant on average, a much higher percentage of nodules are surgically removed in order to rule out malignancy after indeterminate FNA results. Our goal is to identify clinical and ultrasound predictors of benign results in indeterminate nodules, to assist physicians in selecting nodules for surgical removal versus monitoring with ultrasound imaging. Between October 2010 and November 2017 there were 129 patients with 134 thyroid nodules from Temple University Hospital, Jeanes Hospital, and Fox Chase Cancer Center who had a total or partial thyroidectomy after a cytology report of at least one AUS or FLUS thyroid nodule. These patients were evaluated for age, sex, BMI, TSH, fT4, tT3, nodule size, and ultrasonography features to determine if any features were predictive of a benign or malignant thyroid nodule. Additionally, we looked at whether any of these features were more likely to occur in an AUS nodule or a FLUS nodule. We found that none of the demographic factors, thyroid function tests, or ultrasound features were good predictors of malignancy in AUS or FLUS thyroid nodules. We found that AUS nodules are more likely to be malignant than FLUS nodules, and this held true when we accounted for age, sex, smoking history, and BMI. We concluded that demographic factors and thyroid function tests are unable to predict increased risk of malignancy in Bethesda category III nodules, AUS nodules are more likely to be malignant that FLUS nodules, and nodules with at least one suspicious ultrasound feature are more likely to be AUS nodules than FLUS nodules due to AUS nodules having nuclear atypia and FLUS nodules having architectural atypia.