CALCA and medullary thyroid gland carcinoma: Although lower than the incidence of DTC, the incidence of MTC has increased in the last three decades, from 0.14 to 0.21 per 100,000 people [38], thanks to the introduction of serum calcitonin (CT) as a screening test in multinodular goiter and to the use of high-resolution ultrasound [39,40].