In a ROC analysis for the MTC nodules and the non-MTC nodules of the MTC patients, the AUC was 97.1%: on the basis of this curve, the cut-off value of FNA-Ct/serum calcitonin ratio was 11.0, leading to 100% sensitivity and 86.7% specificity (Fig. 5). The gene discussed is CALCA; the disease is medullary thyroid gland carcinoma.