Abstract
Purpose. We sought to investigate the utility of classification and regression trees (CART) classifier to differentiate benign from malignant nodules in patients referred for thyroid surgery. Methods. Clinical and demographic data of 271 patients referred to the Sadoughi Hospital during 2006–2011 were collected. In a two-step approach, a CART classifier was employed to differentiate patients with a high versus low risk of thyroid malignancy. The first step served as the screening procedure and was tailored to produce as few false negatives as possible. The second step identified those with the lowest risk of malignancy, chosen from a high risk population. Sensitivity, specificity, positive and negative predictive values (PPV and NPV) of the optimal tree were calculated. Results. In the first step, age, sex, and nodule size contributed to the optimal tree. Ultrasonographic features were employed in the second step with hypoechogenicity and/or microcalcifications yielding the highest discriminatory ability. The combined tree produced a sensitivity and specificity of 80.0% (95% CI: 29.9–98.9) and 94.1% (95% CI: 78.9–99.0), respectively. NPV and PPV were 66.7% (41.1–85.6) and 97.0% (82.5–99.8), respectively. Conclusion. CART classifier reliably identifies patients with a low risk of malignancy who can avoid unnecessary surgery.
Highlights
Thyroid nodules are common findings in clinical practice
The rate of diagnosis of thyroid cancer has doubled in the past 30 years, despite no tangible decreases in mortality rates. These observations suggest that the increased incidence is more likely a result of overdiagnosis of early forms of thyroid malignancies rather than a true rise in its secular trends [18]
It is conceivable that overdiagnosis of thyroid malignancies translates into a sizable number of unnecessary thyroidectomies and complications associated with this type of surgery, along with detrimental effects on patients’ quality of life [19]
Summary
It is estimated that 4% to 7% of adults in the Unites States have palpable nodules upon examination [1]. Fine needle aspiration (FNA) of the thyroid nodule has become the standard procedure for evaluation of nodule histopathology and is recommended as the main diagnostic strategy in several guidelines and published consensus agreements [3]. FNA has multiple drawbacks inherent in the procedure itself [4], including the technique employed and the experience of the physician performing the aspiration [5, 6]. It is estimated that around 75 000 surgeries for nodules with undetermined diagnoses are performed each year in the United States alone [8]; with a sound systematic approach, at least one third of these operations could be avoided [9]
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