Ultrasound thyroid nodule size and histological findings

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Date
2020-07
Authors
Coetzee, Eldridge Fabian
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University of the Free State
Abstract
Introduction: Thyroid nodules occur in 4-7% of adults with a malignancy risk of 5-15%. Ultrasound plays an important role in the clinical workup of patients with solitary thyroid nodules to differentiate malignant from benign disease. Objectives: To determine if ultrasound single thyroid nodule size can predict the probability of thyroid malignancy. Method: Retrospective cross-sectional study of all thyroidectomies done (benign and malignant) from 2010 to 2016. Ethical clearance was obtained from University of the Free State (HSREC 0664/2017). Data was analyzed by means of descriptive statistics, namely frequencies and percentages for categorical data, medians, and percentiles for numerical data, were calculated. Associations regarding cancer were done for numerical data by means of Kruskal-Wallis test and contingency tables by means of Chi-square or Fischer’s exact test. A p-value of < 0.05 was considered statistically significant. Diagnostic test statistics were calculated, namely sensitivity, specificity, positive and negative predictive values, and likelihood ratios. Results: The overall incidence of thyroid cancer was 24.6%. The median age of thyroid cancer patients was 52.9 years and for benign disease 54 years. Female patients with thyroid cancer were 78.7% and for benign disease 90.1%. Male patients with cancer were 21.2%, for benign disease 9.9%. Papillary thyroid cancer remains the most common type of cancer at 87.8 % and follicular thyroid cancer 12.1%. The average size of thyroid cancer on histology was 2.1 cm and 3.2 cm for the non-cancer group, statistically significant with p-value of 0.0015. Ultrasound nodular size for cancer was 1.7 cm; and 1.9 cm for non-cancer group with p-value 0.209. The association between ultrasound size and histology size for cancer group were not significant with p-value 0.99. Size difference for non-cancer group between histology and ultrasound was significant with p-value 0.02. Conclusions: The study did not prove our hypothesis that ultrasound single nodule size alone, can predict the risk of thyroid cancer. Diagnostic test results with 95% CI reveals a sensitivity of 96%, but a low specificity of 22% to predict the risk of thyroid cancer.
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Dissertation (M.Med. (Surgery))--University of the Free State, 2020, Ultrasound, Thyroid, Nodule, Histology, Cancer, Benign, Non-cancer, Malignant, Thyroidectomy
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