A Monthly Critical Overview of Current Medicine

Molecular Marker for Malignant Thyroid Nodules A n estimated 4o/o of Americans aged 30 to 60 years have palpable thyroid nodules. Fineneedle aspiration cytology, the established evaluation method, has inherent limitations related to sampling and the overlapping cytologic features of benign and malignant lesions. Most patients ultimately undergo surgery, even though less than lOo/o of lesions are definitively classified as carcinoma. There is thus a need for reliable markers that can identify malignant thyrocytes preoperatively. A six-center European group investigated the reliability of CD44v6 and galectin-3, two antigenic proteins expressed by malignant thyrocytes and involved in regulating interactions among cells and between cells and matrix. The two proteins were studied irnmunocytologically, both retrospectively in 1,009 samples of thyroid tissue taken from patients who had undergone surgical resection and prospectively in 226 preoperative fine-needle aspirates. Galectin-3 turned out to be the more useful. Its sensitivity and specificity in discriminating benign from malignant lesions were more than 99o/o and 98o/o, respectively. The positive predictive value and diagnostic accuracy were 92o/o and 99o/o, respectively. Galectin-3 irnmunostaining identified all true follicular malignancies, including five minimally invasive carcinomas.