This year, nearly 54,000 Americans will be diagnosed with thyroid cancer. Fortunately for most, the cancer will be successfully treated. In fact, over 98% of thyroid cancer sufferers will be cancer survivors.
Thyroid cancer is the most common cancer in the endocrine system and the 8th most prevalent cancer in the United States. Malignant cells that form in thyroid gland tissue often create tumors that may or may not spread to other areas of the body.
The butterfly-shaped thyroid gland located at the front of the throat produces hormones that help regulate nearly every process in the body. The gland works by utilizing the mineral, iodine to create important chemical messengers that work to control heart rate, body temperature, metabolism, and the amount of calcium released in the blood.
Signs of Thyroid Cancer
Thyroid cancer often does not exhibit symptoms in the early stages. As a tumor grows however, signs may include:
- Lump or nodule in the neck
- Difficulty breathing
- Difficulty swallowing
- Pain upon swallowing
- Hoarseness in the voice
*A healthy thyroid is generally no larger than a quarter and cannot be felt through the skin.
Who’s at risk for thyroid cancer?
While the chances of developing thyroid cancer is very low in general (1.2% in the U.S.) you may be at increased risk for the disease if you are:
- Aged 25-65
- Have had head and neck radiation
- Have a close family member who has been diagnosed and treated for thyroid disease
Individuals who lack iodine in their diet may also be at increased risk for thyroid cancer.
Diagnosing Thyroid Cancer
Thyroid cancer may be diagnosed through a series of tests and examinations.
Physical Exam—Initially, a physician or other healthcare practitioner will conduct a physical examination. This is to determine if the thyroid gland is overgrown or whether any nodules, bumps, or growths exist. The neck and lymph nodes will also be carefully checked for any swelling or unusual characteristics.
Blood Test—If symptoms are present (or if a thyroid nodule is found), a blood test to examine hormones produced by the thyroid will be ordered. This can indicate that the gland is not functioning properly.
Thyroid Scan—A radioactive substance is swallowed by the patient and travels through the bloodstream to the thyroid gland where it is absorbed. A scan reveals how the thyroid gland and any nodules absorb the substance.
Ultrasound—Sound waves create an image of the thyroid, and any existing nodules that the physician could not feel during the physical examination of the thyroid. An ultrasound may also be ordered to differentiate between benign nodules or cysts and actual thyroid cancer.
Biopsy—Tissue samples are extracted from the thyroid and surrounding areas and examined with a microscope. Cancerous cells may be detected in tissue.
Types of Thyroid Cancer
Several different types of thyroid cancer exist.
Papillary thyroid cancer is the most common and is slow growing. It can spread to nearby lymph nodes.
Follicular thyroid cancer is not as common as papillary thyroid cancer, but can spread to other areas of the body including the lungs and bones.
Medullary thyroid cancer develops from C cells and often releases high levels of calcitonin and carcinoembryonic antigen (CEA) into the body that can be detected by blood tests.
Anaplastic thyroid cancer is very rare, however this type of cancer can spread to the neck and body.
Thyroid lymphoma is very rare, and begins in the immune system cells, growing quite rapidly. This type of thyroid cancer is more common in older adults.
Benign conditions that may resemble thyroid cancer include non-cancerous thyroid nodules. Over 95% of all nodules found in or on the thyroid is non-cancerous. Some thyroid nodules are actually fluid-filled cysts that do not include thyroid tissue.
Stages of Thyroid Cancer
Cancer stages help identify whether or not cells have spread to other parts of the body near or around the thyroid gland. Cancer advances in one of three ways: through tissue, the lymph system, or through the blood.
Thyroid cancer staging is dependent on:
- Type of tumor
- Age of tumor
- Size of tumor
- Distance the initial cancer has spread
Thyroid cancer staging is complex and dependent on the type of tumor and cancer an individual has. Stages range from I through IV. A higher number indicates the increased spread of cancer. Within each stage, a letter lower in the alphabet signifies a less severe stage as well. Cancers of similar stage are treated much the same way.
How is the thyroid cancer stage determined?
The American Joint Committee on Cancer uses a “TNM” system to stage cancer, based on three key pieces of information. These include Tumor (T), Nodes (N), Metastasis (M).
(T) refers to the size of the tumor, how large the cancer is, and whether or not it has spread to nearby structures.
(N) designates whether the cancer has spread to lymph nodes in the nearby area.
(M) refers to metastasis and whether or not the cancer has spread to distant organs including the lungs or liver.
Numbers or letters appearing after T, N, and M provide more specific details about each of the three factors that impact stage designations. After T, N, and M categories have been assigned to the initial cancer, information is combined to determine an overall stage.
Staging helps healthcare practitioners determine the best course of treatment for an individual.
Metastasis and Thyroid Cancer
Cancer may spread from its original location to another part of the body. This is referred to as metastasis. Any metastasized cells are the same as the primary tumor. For example, if the cancer begins in the thyroid and spreads to the bone, it is labeled “metastic thyroid cancer”.
Thyroid Cancer Treatment
There are several treatment options for the treatment of thyroid cancer including:
Surgery—This is the most common treatment for thyroid cancer and includes various surgeries such as a lobectomy, near total thyroidectomy, total thyroidectomy, or a procedure known as a tracheostomy. Each surgery is performed based on the type and size of cancer present.
Radiation therapy, including radioactive iodine therapy—Cancer cells are killed using high energy x-rays or other types of radiation. Either external radiation therapy that utilizes a machine outside the body is used, or internal radiation therapy involving a radioactive substance taken into the body is performed.
Chemotherapy—Drugs are administered either orally or intravenously to kill cancer cells.
Thyroid hormone therapy—Medications are given that block or stop cancer cells from growing.
Targeted therapy—Drugs are used to kill specific cancer cells without harming others.
Close monitoring—A physician monitors a patient’s condition while waiting for symptoms to appear or change.
Several factors impact treatment options and patient prognosis including age, type of thyroid cancer, stage, and patient’s general health. Whether or not cancer is recurring or was completely removed in a prior surgery also affects treatment outlook. Patients who have multiple endocrine neoplasia type 2B (MEN 2B), a genetic disease marked by tumors in the mouth, eyes, and the endocrine system may die prematurely without proper thyroid treatment.
While the National Cancer Institute reports a marked increase of thyroid cancer diagnoses in the U.S. between the early 1990’s and 2013 (rates tripled) the high incidence of new cases has begun to level off. While scientists continue to explore the reasons for the dramatic 30-year increase, and the subsequent drop in thyroid cancer numbers, the disease continues to be at the forefront of endocrine research.
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