Risk Factors for Malignancy in Indeterminate Thyroid Nodules

Since roughly 70-80% of indeterminate thyroid nodules (ITN) are diagnosed as benign from histologic follow-up of fine-needle aspiration cytology (FNAC), researchers have conducted numerous studies to identify the clinical risk factors that predict malignancy.

For their review of 19 such studies published through December 2012, a team of European scientists examined data on 3,494 patients who underwent FNAC that indicated ITN.

Within the pooled patient population, the prevalence of malignant nodules was 28%, though it was 26% among females and 34% among males. Thus, men appeared to have a higher risk of malignant ITN, but unlike patient gender, the researchers were unable to determine a possible link between patient age and malignancy because age-related demographics were unavailable.

Nodule size was also difficult to analyze, due to the differing reporting methods employed in the data sources. Experts have disagreed on the efficacy of nodule size as a malignancy parameter, and the conflicting results among the individual studies included in the meta-analysis failed to clarify the controversy.

Nevertheless, the authors concluded that male patients who have nodules >4 cm in diameter “should be considered at higher risk of cancer.”