Association between thyroid nodule size and malignancy rate

Area of Science:

• Endocrinology
• Oncology
• Diagnostic Imaging

Background:

• Diagnostic performance of ultrasound-fine needle aspiration (FNA) for thyroid nodules is variable.
• Identifying malignancy risk in thyroid nodules requires reliable predictors.

Purpose of the Study:

• To evaluate thyroid nodule size and cytological classification as predictors of malignancy risk.
• To assess the diagnostic utility of FNA in relation to nodule size.

Main Methods:

• Retrospective cohort analysis of 499 patients undergoing thyroid surgery (2004-2015).
• Analysis of 503 thyroid nodules, correlating size and cytological class with malignancy.
• Evaluation of FNA sensitivity, specificity, and false negative rates based on nodule size.

Main Results:

• 19.5% of analyzed thyroid nodules were malignant.
• Nodule size (less than or equal to 3.0 cm vs. greater than 3.0 cm) did not significantly correlate with malignancy risk (p=0.49).
• Cytological classification was significantly associated with higher malignancy risk (p<0.01), while FNA sensitivity was 71.4% and specificity 100%.

Conclusions:

• Thyroid nodule size is not a reliable predictor of malignancy, independent of FNA cytology.
• Routine thyroid lobectomy based solely on nodule size (>= 3.0 cm) is not currently supported by evidence.
• Cytological assessment remains crucial for determining malignancy risk in thyroid nodules.