Endocrine Abstracts

Fine needle aspiration biopsy (FNAB) has become the mainstay of thyroid nodule evaluation. While the overall accuracy of FNAB is excellent, an indeterminate or suspicious biopsy can pose a diagnostic and management dilemma. Fortunately, only 20-25% of indeterminate nodules are ultimately found to be malignant. Unfortunately, approximately 75-80% of patients undergo a surgical procedure that may have not been necessary. Recent advances in molecular diagnostics such as immunocytochemistry, enzyme activity assays, and quantitative RT-PCR have made it possible to further analyze products from fine needle aspiration biopsy in an attempt to determine whether a nodule is malignant or benign. In order for a molecular marker to be useful as an aid for cytologic diagnosis of thyroid nodules and thyroid cancer, the marker must be able to reliably distinguish benign from malignant neoplasms, particularly in nodules that are cytologically indeterminate. In order to be clinically useful, a marker must also be confirmed by multiple different investigators as a useful tool in diagnosis of thyroid cancer. These markers must also be able to be measured fairly easily from products of fine needle aspiration biopsies either by immunocytochemistry, a functional assay, or some accurate form of RT-PCR. Finally, a molecular marker would be of further usefulness if it had prognostic significance in patients diagnosed with thyroid carcinoma as well as providing insight into pathogenesis and treatment options in these patients. There have been at least 50 molecular markers that have been analyzed in patients with thyroid nodules. New potential markers appear in the literature with an increasing frequency, yet routine clinical use of any of these markers is still quite rare. Two promising markers for clinical use in the near future are thyroid peroxidase and galectin-3. These markers will be discussed in detail.