TELOMERASE ACTIVITY IN THE DIFFERENTIAL-DIAGNOSIS OF PAPILLARY CARCINOMA OF THE THYROID

Background. Although fine-needle aspiration (FNA) is 90% sensitive in the detection of papillary carcinoma (PC) of the thyroid, its specific ity has been reported as low as 52%. Consequently, patients who have a n FNA suspicious for PC may undergo operation for a benign process. Th e ribonucleoprotein. telomerase has been noted to be activated in a wi de variety of carcinomas. We examined 30 PCs for telomerase activity t o determine whether this would be a useful adjunct to FNA in the diagn osis of lesions suspicious for PC. Methods. Standard telomere repent a mplification protocol assays were performed on fresh frozen tissue sam ples from 30 PCs, 3 benign nodules, and 10 normal thyroids. Results. T elomerase activity was documented in 20 of 30 (67%) of the PCs, 0 of 3 benign nodules, and 0 of 10 normal thyroids. In all, 11 of the 20 PCs had FNA cytology that was nondiagnostic of PC, and 2 of the benign no dules had FNA that was suspicious for PC. Conclusions. The telomerase assay appears useful in the distinction of benign from malignant thyro id lesions that have FNA suspicious for but not diagnostic of PC. On t he basis of these findings, a prospective trial examining telomerase a ctivity in FNAs suspicious for thyroid cancer has been initiated.