Thyroid cancer is a disease of the thyroid gland (thyroid gland is a type of endocrine glands that release hormones that regulate metabolism).
There are four main types of thyroid cancer - papillary cancer, follicular cancer, medullary cancer, and anaplastic cancer. Thyroid cancer, if left untreated, can spread to other parts of the body including lymph nodes, nerves and blood vessels through a process known as metastasis.