Thus, in summary, the ATA MTC guidelines constituted a positive stimulus to publish further evidence for Ct-guided pre-emptive thyroidectomy for RET gene mutation carriers and the conclusion is drawn on the basis of experience expressed in Lisbon and published later evidence that the integrated algorithm based on age - Ct - type of RET mutation should be considered in the decision of pre-emptive thyroidectomy. This evidence concerns the gene RET and medullary thyroid gland carcinoma.