Thyroid Cancer Glossary

Ablate: To destroy the function of an organ or tissue. Radioactive iodine treatment ablates thyroid tissues.

Anaplastic thyroid cancer: Undifferentiated, fast-growing thyroid cancer.

Benign: A word to describe a non cancerous growth or mild illness.

Biopsy: Removing tissue from patients for examination.

Endocrine glands: Glands that secrete hormones into the bloodstream.

Endocrinologists: Doctors who specialize in the care of patients with disorders of the endocrine glands.

Endocrinology: The study of diseases and disorders of the endocrine system (like thyroid diseases and diabetes). The endocrine system consists of glands in the body that release hormones directly into the blood. The thyroid gland, for example, releases thyroid hormones into the bloodstream, giving the hormones access to all other cells of the body. The purpose of the secreted hormones is to evoke a specific response in other faraway cells.

Euthyroidism: Having the proper amount of thyroid hormone in the body.

Fine needle aspiration biopsy (FNAB): A biopsy obtained by inserting a thin needle into a thyroid nodule and extracting cells for analysis. Also called fine needle aspiration (FNA).

Follicles: Microscopic spherical units that make up the thyroid gland.

Follicular cancer: A type of cancerous growth composed of thyroid follicular cells; also called follicular carcinoma. Follicular cancer is a type of well-differentiated thyroid cancer.

Free T4: The amount of T4 in the bloodstream that is not bound to carrier proteins.

Hormones: Chemicals produced by an endocrine gland and released into the blood. Hormones travel to other organs of the body where they produce their effect.

Hyperthyroidism: An abnormality of the thyroid gland in which secretion of thyroid hormone is increased and no longer under normal control. Characterized by increased metabolism.

Hypothalamus: An endocrine gland in the brain that releases thyrotropin-releasing hormone (TRH).

Hypothyroidism: Decreased production of thyroid hormone, leading to symptoms of thyroid insufficiency.

Iodine: A nonmetallic element found in food. When iodine is ingested, much of it goes to the thyroid gland. Iodine is necessary to make thyroid hormone and for normal thyroid function.

Lobes: The two halves of the thyroid gland that give it its butterfly-like shape. The right lobe is often slightly larger than the left lobe.

Magnetic resonance imaging (MRI): An imaging procedure that produces a clear three-dimensional picture.

Medullary thyroid cancer: Thyroid cancer arising from the parafollicular cells. Although it grows slowly, it may be harder to control than papillary and follicular tumors. It is more aggressive than well-differentiated thyroid cancer and tends to spread to other parts of the body.

Metabolism: The use of calories and oxygen to produce energy.

Metastatic disease: Cancer that has spread from its original site to other parts of the body.

Metastatic: relating to metastasis

Metastasis: The shifting of a disease or its local manifestations from one part of the body to another

Papillary cancer: A well-differentiated thyroid cancer composed of thyroid follicular cells also called papillary carcinoma. The nuclei of the cells are large and seem to overlap.

PET (positron emission tomography) scan: An imaging technique that uses radioactive positrons (positively charged particles) to detect subtle changes in the body’s metabolism and chemical activities.

Pituitary gland: A small gland the size of a peanut that is located behind the eyes at the base of the brain. It secretes hormones that control other glands (including the thyroid) as well as growth. It secretes thyroid stimulating hormone (TSH), a hormone that helps control thyroid function, as well as other hormones involved in endocrine function.

Radioactive iodine (RAI): Radioactive isotopes of iodine (131I) used in the diagnosis and treatment of some thyroid disorders. RAI is also used for treatment of thyroid cancer, in which cases the patient takes a large dose of radioactive iodine to kill any recurrent or metastasized thyroid cells.

Radioactive iodine uptake (RAIU): A test measuring the amount of orally administered radioactive iodine taken up by the thyroid gland.

RAI ablation: Administration of a radioactive form of iodine (131I) to try to destroy any remnant (normal or cancerous) thyroid tissue left after surgery in the thyroid bed or neck.

Recombinant DNA technology: The technique of isolating genes from one organism and purifying and reproducing them in another organism.

Recombinant human thyroid-stimulating hormone (rhTSH): A large protein molecule almost identical to human thyroid-stimulating hormone that has been produced using recombinant DNA technology also known as Thyrogen.

Sensitivity: The ability of a test to detect the proportion of true positive results for the disease that the test is intended to reveal. In other words, the probability that, given the presence of disease, a test result indicates the presence of disease.

Signs: Those characteristics that a physician can objectively detect or measure. If the physician touches the patient’s skin and notes that it is warm and moist, this is a sign.

Specificity: The ability of a test to detect the proportion of true negative results for the disease that the test is intended to reveal. In other words, the probability that, given the absence of disease, a test result excludes disease.

Symptoms: Those problems that a patient notices or feels. If a patient feels hot, this is a symptom.

T-Z T3 (triiodothyronine): The secondary hormone produced by the thyroid gland.

T4 (thyroxine): The primary hormone produced by the thyroid gland.

Tg test: A test that measures the level of thyroglobulin (Tg) in the blood. Tg tests are used in the postsurgical monitoring of thyroid cancer patients to check for thyroid remnants or cancer metastases.

Thyroid Hormone Therapy (THT): Therapy consisting of thyroid hormone medications.

Thyroglobulin (Tg): A large protein that acts as a storage site for thyroid hormones within the thyroid gland. Following surgical removal of a cancerous thyroid gland, the level of Tg in the bloodstream can be monitored to detect thyroid cancer recurrence.

Thyroid gland: A two-lobed gland lying at the base of the throat that produces hormones essential for a variety of metabolic processes in the body. When iodine is ingested, much of it goes to the thyroid gland.

Thyroid hormone suppression therapy (THST): In patients who have had a thyroidectomy for thyroid cancer, physicians usually prescribe a moderate excess of thyroid hormones to create a negative feedback loop that suppresses thyroid-stimulating hormone production by the pituitary gland. TSH production is suppressed to avoid stimulating existing thyroid remnants or thyroid cancer cells.

Thyroid hormones: T4 and T3, two hormones that tell the body how fast to work and how to use energy. T4 (thyroxine) is the primary hormone produced by the thyroid gland and T3 (triiodothyronine) is the secondary hormone produced by the thyroid gland.

Thyroid nodules: Small lumps or growths that can be felt in the neck. They can be benign or malignant. In a normal gland or a multinodular goiter, thyroid nodules may be solitary or multiple. Imaging tests, blood tests, and fine needle aspiration biopsies (FNAB) are used to perform a clinical evaluation of thyroid nodules.

Thyroid remnant: Some part of the original thyroid gland remaining after thyroidectomy surgery.

Thyroid scan: A picture of the thyroid gland obtained with a scanner and radioactive materials.

Thyroid-stimulating hormone (TSH): A hormone secreted by the pituitary gland that stimulates the thyroid gland to produce the thyroid hormones T4 and T3. When the thyroid gland is not working properly, the pituitary releases large amounts of TSH to try to stimulate the thyroid gland into producing thyroid hormone. High amounts of TSH circulating in the bloodstream thus indicate that the thyroid is not secreting enough hormones.

Thyroid ultrasound: A type of scan that uses sound waves that pass into the body and reflect back to produce images.

Thyroidectomy: Surgical removal of the thyroid gland.

Thyrotropin alfa: The generic name for Thyrogen®.

Thyrotropin: Another name for thyroid-stimulating hormone (TSH).

Thyroxine (T4): The primary hormone produced by the thyroid gland.

TNM: A tumor staging system for classifying patients with thyroid cancer into groups based on tumor size (T), presence of lymph node metastases (N), and the presence of distant metastases (M). Also referred as “tumor-node-metastasis.”

Triiodothyronine (T3): The secondary hormone produced by the thyroid gland.

TSH test: A test to measure the amount of thyroid-stimulating hormone (TSH) in the bloodstream.

Ultrasound: A type of scan that uses sound waves that pass into the body and reflect back to produce images.

Well-differentiated thyroid cancers (WDTC) : Papillary or follicular thyroid cancers showing well-differentiated cell structures.

Whole body scan (WBS): A scan of the whole body used to view areas of radioactive iodine uptake after its oral administration. It requires high TSH either by stopping thyroid medication or by taking Thyrogen