A Cohort Analysis of Clinical and Ultrasound Variables Predicting Cancer Risk in 20,001 Consecutive Thyroid Nodules

CONTEXT: Assessing thyroid nodules for malignancy is complex. The impact of patient and nodule factors on cancer evaluation is uncertain. OBJECTIVES: To determine precise estimates of cancer risk associated with clinical and sonographic variables obtained during thyroid nodule assessment. DESIGN: Analysis of consecutive adult patients evaluated with ultrasound-guided fine-needle aspiration for a thyroid nodule ≥1 cm between 1995 and 2017. Demographics, nodule sonographic appearance, and pathologic findings were collected. MAIN OUTCOME MEASURES: Estimated risk for thyroid nodule malignancy for patient and sonographic variables using mixed-effect logistic regression. RESULTS: In 9967 patients [84% women, median age 53 years (range 18 to 95)], thyroid cancer was confirmed in 1974 of 20,001 thyroid nodules (9.9%). Significant ORs for malignancy were demonstrated for patient age 75% compared with predominantly solid, P < 0.0001 for both], and the presence of additional nodules ≥1 cm [OR: 0.69 (0.60 to 0.79) for two nodules, OR: 0.41 (0.34 to 0.49) for three nodules, and OR: 0.19 (0.16 to 0.22) for greater than or equal to four nodules compared with one nodule, P < 0.0001 for all]. A free online calculator was constructed to provide malignancy-risk estimates based on these variables. CONCLUSIONS: Patient and nodule characteristics enable more precise thyroid nodule risk assessment. These variables are obtained during routine initial thyroid nodule evaluation and provide new insights into individualized thyroid nodule care.