Thyroid Nodule Shape Independently Predicts Risk of Malignancy

Area of Science:

• Endocrinology
• Oncology
• Radiology

Background:

• Current thyroid nodule cancer risk models rely on composition, echogenicity, margins, and microcalcifications.
• Nodule shape is an emerging factor for predicting biopsy necessity.

Purpose of the Study:

• To investigate if a nodule's spherical shape independently correlates with cancer risk.
• To determine the association between nodule sphericity and malignancy.

Main Methods:

• Prospective cohort study at a US academic healthcare system.
• Included patients with 1-2 thyroid nodules (>1 cm, predominantly solid).
• Calculated nodule long to short ratio (sphericity) and correlated with biopsy/histopathology results.

Main Results:

• Malignant nodules had a significantly lower long to short ratio (more spherical) than benign nodules (1.63 vs. 1.74, P < 0.0001).
• Cancer risk increased as the ratio approached 1.0 (spherical shape).
• Nodule sphericity, younger age, and male sex were independent predictors of cancer risk.

Conclusions:

• Increased thyroid nodule sphericity, indicated by a long to short ratio near 1.0, is linked to higher malignancy risk.
• This association is independent of patient age, sex, and nodule size.
• Incorporating nodule sphericity into risk stratification may enhance clinical decision-making for thyroid nodules.