Thyroid cancer starts in the Thyroid gland. The most common types of thyroid cancer are papillary and follicular. Thyroid cancer may spread to other parts of the body, such as the lungs, bones, and occasionally the brain. Such conditions are referred to as advanced or Metastatic Thyroid Cancer. Retevmo was studied in the clinical trial of people 12 years of age and older with RET-positive advanced Thyroid Cancer (including medullary, papillary, anaplastic, and Hurthle cell), and tumors were shrunk or may disappear completely.