Spanish Study for Molecular Characterization of Thyroid Carcinoma

Inclusion Criteria: 1. All participants must be over 18 years old 2. Obtaining the informed consent signed by the patient or his legal representative. 3. Have a paraffinized tumor sample available for analysis in the central laboratory, preferably from total thyroidectomy. 4. Life expectancy greater than 6 months. 5. Thyroid carcinoma with a date of initial histological diagnosis before January 1, 2021 of the types: (1) Differentiated thyroid carcinoma (DTC) refractory to radio-iodine, including papillary carcinomas, follicular carcinomas, poorly differentiated thyroid carcinomas, and the corresponding different variants. The radio-refractoriness criteria will be defined by medical criteria and / or by decision of the tumor committee (depending on the organization of each hospital) or (2) Medullary thyroid carcinoma (MTC). 6. Potential candidate patients must meet at least one of the following premises: 1. Patients with advanced / metastatic disease in wait \& see follow-up. 2. Patients with advanced / metastatic disease currently undergoing treatment or in progression to any type of multikinase inhibitor, such as, for example: sorafenib, lenvatinib, cabozantinib, axitinib, vandetanib, ... 3. Patients with advanced / metastatic disease under treatment or in progression to treatments that inhibit immune checkpoints (anti programed death (PD-1) or its ligand (PD-L1), anti Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4), others) or who are participating in clinical trial regimen. They must be patients who have previously progressed to multikinase inhibitors. Exclusion Criteria: 1. Patients affected by other malignant histologies not mentioned in the previous section (eg melanoma, lymphoma, sarcoma, ...) or benign tumors exclusively of the thyroid gland. 2. Patients with radioiodine sensitive differentiated thyroid carcinoma or anaplastic thyroid carcinomas. 3. Patients with refractory radioiodine differentiated thyroid carcinoma and advanced medullary thyroid carcinomas with the possibility of local ablative treatment with radical or curative intent (surgery, radiosurgery, radio-ablation, ...).