Comparison of microarray analysis of fine needle aspirates and tissue specimen in thyroid nodule diagnosis

Serum biomarkers of papillary thyroid cancer

Objective

To identify serum biomarkers of papillary thyroid cancer.

Methods

Prospective analysis was performed of banked tumor and serum specimens from 99 patients with thyroid masses. Enzyme-linked immunosorbent assay (ELISA) was employed to measure levels of five serum proteins previously demonstrated to be up-regulated in papillary thyroid cancer (PTC): angiopoietin-1 (Ang-1), cytokeratin 19 (CK-19), tissue inhibitor of metalloproteinase-1 (TIMP-1), chitinase 3 like-1 (YKL-40), and galectin-3 (GAL-3). Serum levels were compared between patients with PTC and those with benign tumors.

Results

A total of 99 patients were enrolled in the study (27 men, 72 women), with a median age of 54 years. Forty-three patients had PTC and 58 cases were benign tumors. There were no statistically significant differences when comparing all five different biomarkers between PTC and other benign thyroid tumors. The p-values were 0.94, 0.48, 0.72, 0.48, and 0.90 for YKL-40, Gal-3, CK19, TIMP-1, and Ang-1, respectively.

Conclusion

Serum levels of four of the five proteins were elevated in patients with thyroid masses relative to normal values. However, the difference between benign and PTC was not significant. Two of the markers (Gal-3 & TIMP-1) displayed a greater potential difference, which may warrant further investigation. This study suggests that other serum markers should be sought. This is the first study to investigate potential serum biomarkers based on over-expressed proteins in thyroid cancer versus benign pathology.

The quest for diagnostic molecular markers for thyroid nodules with indeterminate or suspicious cytology

Thyroid nodules are very common and fine needle aspiration (FNA) is a very sensitive means of diagnosis. However, its limitations include the fact that the cytology reports are often indeterminate or suspicious only. The quest for adjunctive measures to improve its specificity has been ongoing for decades, but significant results have remained elusive. The potential use of diagnostic molecular markers appears to be the most promising area of research at this time.

Predicting malignancy in thyroid nodules: molecular advances

Over the last several years, a clearer understanding has developed of the genetic alterations underlying thyroid carcinogenesis. This knowledge can be used to tackle 1 of the challenges facing thyroidologists: management of the indeterminate thyroid nodule. Despite the accuracy of fine-needle aspiration cytology, many patients undergo surgery to diagnose malignancy and better diagnostic tools are required. A number of biomarkers have recently been studied and show promise in this setting. In particular, BRAF, RAS, PAX8-PPARγ, microRNAs, and loss of heterozygosity have each been demonstrated as useful molecular tools for predicting malignancy and can potentially guide decisions regarding surgical management of nodular thyroid disease. This review summarizes the current literature surrounding each of these markers, highlights our institution's prospective analysis of these markers, and describes the subsequent incorporation of molecular markers into a management algorithm for thyroid nodules.