Definition and Overview
Thyroid cancer occurs as a result of uncontrolled growth of cancer cells in the thyroid gland. It may be primary or secondary (metastatic).
The thyroid is a pair of glands located behind the Adam’s apple or the thyroid cartilage, or on the sides of the windpipe. It plays a critical role in hormone production and regulation, as well as management of metabolic functions. In addition, it secretes three hormones; T3 (triiodothyronine) and T4 (thyroxine), which controls metabolism while calcitonin regulates the level of calcium in the blood.
Thyroid cancer normally affects the cells that manufacture and manage these hormones. These include follicular cells (for T3 and T4), parafollicular cells (calcitonin), stromal, and immune cells.
Although more than 60,000 cases are diagnosed every year in the United States, thyroid cancer remains rare. It doesn’t have any known cure, but the early detection is common and survival rates are very high.
Causes of Condition
The actual cause of thyroid cancer remains unknown. However, risk factors have been identified and these include the following:
Age: Most of those who were diagnosed with thyroid cancer are no more than 55 years old. In fact, about 2% of patients are teens and children.
Gender: Thyroid cancer affects more women than men. On the average, at least 47,000 women develop it compared to less than 20,000 men. The incidence is also late among men, who are often diagnosed when they’re already around 60 to 70 years old.
Diet: Thyroid cancer is more common in countries whose diet severely lacks iodine, a trace mineral that promotes proper thyroid function by correctly using calories. Follicular cells need iodine, which they obtain from the bloodstream.
Genetics and family history: Familial medullary thyroid carcinoma develops when the cause of the medullary thyroid carcinoma is a defective gene. Those who are diagnosed with familial adenomatous polyposis (FAP) have a higher risk of both colon and thyroid cancer.
Other diseases: Cowden syndrome is a rare disease caused by a PTEN gene defect. It is characterized by multiple hamartomas (benign growths). Acromegaly, meanwhile, happens when the body creates an excessive growth hormone.
Radiation exposure: Studies have shown that adults who were exposed to radiation when they were younger have a higher risk of having thyroid cancer later in life. The level, severity, and length of exposure, however, affect the chances of this risk.
- Appearance of nodules or a lump in the throat
- A lump that persists despite treatments
- Change of voice quality (hoarseness)
- Neck swelling
- Pain in the neck area
- Difficulty in swallowing
- Difficulty in breathing
- Unusual weight loss
- Feeling of fatigue
- Coughing without colds
- Swelling of the lymph nodes of the neck
- High calcium levels
Types of Thyroid Cancers
Papillary – accounts for more than 75% of thyroid cancers. It affects the papillary cells of the cancer and is common among women and adults who have been treated with some form of radiation when they were younger.
Follicular – more than 12% of thyroid cancers are follicular. It is normally detected in middle-aged women. A variant of follicular thyroid carcinoma is Hurthle cell cancer, which is less responsive to treatment.
Parathyroid cancer – it is the cancer that affects the parathyroid glands, which are found behind the thyroid gland.
Medullary – this may be hereditary and caused by a defective gene, in which it becomes familial medullary thyroid carcinoma. It affects the C cells or those responsible for producing calcitonin.
Thyroid sarcoma – is a type of cancer that affects the soft tissues of the thyroid.
Anaplastic – a rare form of thyroid cancer that normally affects women who are more than 60 years old. It is aggressive and has the lowest prognosis among the types of thyroid cancer.
Thyroid lymphoma – is a kind of lymphoma caused by cancerous lymphatic cells in the thyroid gland.
Many of the thyroid cancer cases are discovered through a medical exam as part of an annual check-up or exhibited symptoms especially a persistent cough or a growing nodule or lump in the throat. The doctor may also request for tests if swollen lymph nodes are found around the neck area.
If the nodules are large enough (at least a centimeter), the doctor may perform a fine needle aspiration procedure (FNA biopsy), where a sample of the fluid and cells is obtained by inserting a hollow thin needle into the nodule. For minimum discomfort, the patient may be provided with local anesthesia. This procedure may be repeated multiple times to gather enough samples or when test results indicate suspicious findings.
If the doctor suspects thyroid cancer based on the symptoms, imaging tests such as radioiodine scan, CT scan, chest X-ray, and radioiodine scan will be requested. Blood tests may be used to identify abnormal thyroid hormone production or high calcium levels.
Who To See and Available Treatments
Patients who are diagnosed with thyroid cancer are referred to an oncologist.
Early detection of thyroid cancer means a very good prognosis. Often, patients with differentiated cancers such as papillary, medullary, and follicular cancer have nearly 100% chance of survival if they are diagnosed at stage 1.
Available treatments are the following:
Surgery – is the main form of treatment unless it’s an anaplastic thyroid cancer. Surgery removes small tumors that have not spread to the rest of the thyroid (lobectomy), the entire thyroid gland (thyroidectomy), or lymph nodes.
Radioactive iodine therapy – involves implanting radioactive iodine in capsule or liquid form to destroy the remaining cancer cells that have not been removed during surgery.
Thyroid hormone therapy – is needed if the entire thyroid gland has been removed. It is a long-lasting treatment, and the medications have to be taken daily.
Anaplastic cancer patients are often treated with external beam radiation and chemotherapy.
Recently, the Food and Drug Administration has approved, through a priority review, the use of lenvatinibor Lenvima for patients with a differentiated but progressive thyroid cancer. Those who qualify for this are those who have already gone through the standard treatments with poor results.