Is nodule size an independent predictor of thyroid malignancy?

A decision to proceed with thyroidectomy or to perform more extensive thyroidectomy based on nodule size is controversial. It was our hypothesis that larger nodules are more likely to be malignant, and, as a result, nodule size may be useful for guiding operative decision making.

Data was obtained from a prospectively maintained database for patients with nodular thyroid disease evaluated from 1990 to 2007. Logistic regression analysis was performed to determine if there was a significant relationship between nodule size and malignancy based on final pathology. The relationship of nodule size and malignancy was further evaluated for specific diagnostic categories of fine needle aspiration biopsy (FNAB).

1023 patients were evaluated for nodular thyroid disease and 676 underwent thyroidectomy. Mean size was 4.4 +/- 2.4 cm for benign and 3.3 +/- 2.2 cm for malignant nodules (P < .05). The size of benign and malignant nodules, as a function of FNAB, was not significantly different.

Increasing nodule size was not predictive of thyroid malignancy suggesting that it should not be used in lieu of FNAB for therapeutic decision making.