Telomerase activity in surgical specimens and fine-needle aspiration biopsies from hyperplastic and neoplastic human thyroid tissues

Background Telomerase activity (TA) indicates malignancy, but activated lymphocytes also express TA. Correlation between TA in thyroid tissues and fine-needle aspiration (FNA) samples and knowledge about TA in adjacent tissue are of importance. Methods The telomeric repeat amplification protocol assay followed by enzyme-linked immunosorbent assay detection was performed on 78 thyroid cases including 53 suspected malignancies, preoperative and perioperative FNA specimens, and adjacent tissue. Results Benign lesions in cancer-suspected cases were TA negative. Eight of 13 papillary (62%) and 4 of 5 follicular (80%) tumors were TA positive (TA+). Lower TA was observed in conventional papillary cancer than in follicular, tall cell variant of papillary and anaplastic cancers. Adjacent tissues with lymphocyte infiltration were TA+ in 9 of 17 cases (53%). Nine of 65 adjacent tissues (14%) were TA+. Three of 6 preoperative and 9 of 11 perioperative FNA samples from malignant tumors corresponded to the tissue TA. Conclusions High TA may reflect more severe thyroid cancer. Telomerase activity in FNA biopsies does not add reliable diagnostic information, and presence of lymphocytes can give false-positive results.