The data used originate from the web-based database of the Italian Thyroid Cancer Observatory (ITCO), opened in 2013 at the Thyroid Cancer Center of the Sapienza University of Rome and including 49 other thyroid cancer centers in Italy. The data collected on more than 10000 patients contain demographic and biometric information, circumstances of diagnosis, tumor pathology, surgical and radioactive iodine treatments, and results of periodic follow-up examinations. Cases with histological diagnosis of DTC have responses to initial treatment classified as excellent, biochemically incomplete, structurally incomplete or indeterminate based on data collected during the clinical evaluation at the 1-year follow-up visit.