Serum thyroid-stimulating hormone as a diagnostic marker for cancer in atypia of undetermined significance/follicular lesion of undetermined significance nodules.

Background: Several studies have assessed the efficacy of thyroid-stimulating hormone (TSH) as a diagnostic marker of thyroid cancer (TC), with inconsistent findings. However, few studies have investigated its role in indeterminate thyroid nodules (TNs), particularly in those with atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS). The objective of this study was to evaluate preoperative TSH levels as a diagnostic marker for cancer in AUS/FLUS nodules.

Methods: A retrospective analysis was conducted on patients who underwent thyroidectomy with a primary cytological diagnosis of AUS/FLUS. The association between preoperative TSH levels and the final anatomopathological diagnosis (benign vs. differentiated TC) was examined.

Results: The analysis included 109 patients. The median TSH level was higher in patients with malignant nodules (2.32 mIU/L) than in those with benign pathology (1.60 mIU/L) (P=0.04). Receiver operating characteristic (ROC) curve analysis revealed that the TSH level was a potential indicator for the coexistence of thyroid malignancy, with a significant area under the curve of 0.61 (P=0.04). The optimal diagnostic cutoff point for TSH levels was ≥3.06 mIU/L.

Conclusions: This study demonstrated that TSH levels are an acceptable and useful marker to rule in rather than rule out TC in AUS/FLUS nodules.