Measurement of TFF3 mRNA in aspirates from thyroid nodules using mesh filtration: The first clinical trial in 130 cases

Measurement of gene expression levels in thyroid tumor cells in aspirates was difficult because it is interfered with peripheral blood cells or infiltrating lymphocytes. In this study, we established a novel method to separate thyroid tumor cells from blood cells efficiently with mesh filtration. The expression level of trefoil factor 3 (TFF3) mRNA was estimated using LGALS3 mRNA as an internal control (T/G ratio) in 148 preoperative thyroid aspirates. Intra-assay coefficients of variation (CV) of T/G ratio for high, moderate, and low samples were 6.5%, 2.5%, and 9.7%, respectively, and inter-assay CV for high, moderate, and low samples were 27.7%, 21.9%, and 38.2%, respectively. Nondiagnostic samples in terms of T/G ratio and cytology were 12.2% and 16.9%, respectively. We observed no interference with the data by contaminating blood cells. Among these patients, 12 patients received more than two repeated aspirations. We did not observe a marked day-to-day variation except in two cases. All 13 preoperative aspirates diagnosed as malignant by cytology showed an extremely low T/G ratio, whereas 93 aspirates diagnosed as benign by cytology showed extremely varied T/G ratios and 21.5% of them showed a T/G ratio below the cut-off value. Eleven cases underwent surgery. All nodules showing a low T/G ratio were diagnosed as papillary carcinoma by pathological diagnosis. However, one nodule diagnosed as follicular adenoma after surgery showed a high T/G ratio. Our present method may be a promising preoperative test for measuring mRNAs in thyroid aspirates.