What is Thyroid Cancer?
Thyroid cancer is cancer that develops from the tissues of the thyroid gland. It is a disease in which cells grow abnormally and have the potential to spread to other parts of the body. Symptoms can include swelling or a lump in the neck. Cancer can also occur in the thyroid after spread from other locations, in which case it is not classified as thyroid cancer.
Risk factors include radiation exposure at a young age, having an enlarged thyroid, and family history. There are four main types – papillary thyroid cancer, follicular thyroid cancer, medullary thyroid cancer, and anaplastic thyroid cancer. Diagnosis is often based on ultrasound and fine needle aspiration. Screening people without symptoms and at normal risk for the disease is not recommended as of 2017.
Treatment options may include surgery, radiation therapy including radioactive iodine, chemotherapy, thyroid hormone, targeted therapy, and watchful waiting. Surgery may involve removing part or all of the thyroid. Five year survival rates are 98% in the United States.
Signs and symptoms
Most often the first symptom of thyroid cancer is a nodule in the thyroid region of the neck. However, many adults have small nodules in their thyroids, but typically under 5% of these nodules are found to be cancerous. Sometimes the first sign is an enlarged lymph node. Later symptoms that can be present are pain in the anterior region of the neck and changes in voice due to an involvement of the recurrent laryngeal nerve.
Thyroid cancer is usually found in a euthyroid patient, but symptoms of hyperthyroidism or hypothyroidism may be associated with a large or metastatic well-differentiated tumor.
Thyroid nodules are of particular concern when they are found in those under the age of 20. The presentation of benign nodules at this age is less likely, and thus the potential for malignancy is far greater.
Causes
Thyroid cancers are thought to be related to a number of environmental and genetic predisposing factors, but significant uncertainty remains regarding their causes.
Parathyroid Cancer
Almost all parathyroid problems are caused by one or more of the parathyroid glands producing too much parathyroid hormone (PTH). This is called hyperparathyroidism, and it causes a number of medical problems such as osteoporosis, mental disorders, ulcers, pancreatitis, kidney stones, and other symptoms. However, the overgrowth of parathyroid tissues responsible for this overproduction of PTH is not malignant, and therefore, these overgrowths are usually referred to as parathyroid adenomas (benign parathyroid hormone secreting tumors).
Parathyroid disease is caused by a single bad parathyroid gland more than 90% of the time. Since there are 4 parathyroid glands, removing one bad gland becomes the simple way to cure the problem.
Parathyroid glands are no different than every other tissue in the human body—they can develop cancer in them. Parathyroid cancer, however, is extremely rare, with only a few dozen cases seen every year in the US. Parathyroid cancer is so rare that most doctors have never seen it.
Very rarely, a parathyroid gland will become cancerous (the overgrowth is composed of malignant cells). Since parathyroid cells make parathyroid hormone (PTH) as their only purpose in life, those that are cancerous (growing out of control) will make PTH "out of control" as well.
In fact, that is a big tip-off that a patient with hyperparathyroidism might have parathyroid cancer since these malignant tumors will produce "massive" amounts of parathyroid hormone instead of "large" amounts like are seen with benign parathyroid tumors (adenomas or hyperplasia). All patients with hyperparathyroidism have elevated parathyroid hormone in their blood, those with benign disease tend to have levels in the "hundreds" where as those with parathyroid cancer tend to have values in the "thousands."