Thyroid Cancer (cont.)
Benjamin Wedro, MD, FACEP, FAAEM
Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.
In this Article
- Thyroid cancer facts*
- What is the thyroid?
- What is the thyroid cancer?
- What causes thyroid cancer?
- What are the risk factors for thyroid cancer?
- What are the symptoms and signs of thyroid cancer?
- What are thyroid nodules?
- What are the different types of thyroid cancer?
- How is thyroid cancer diagnosed?
- How is thyroid cancer staging determined?
- What kinds of specialists treat thyroid cancer?
- What is the treatment for thyroid cancer?
- Thyroid hormone
- Radioactive iodine
- What kind of support is available for those with thyroid cancer?
- What is the prognosis for patients with thyroid cancer?
- Can thyroid cancer be prevented?
- Thyroid Conditions Slideshow
- Take the Quiz on Thyroid Disorders
- Thyroid Medical Anatomy
- Find a local Oncologist in your town
What are the symptoms and signs of thyroid cancer?
Most often, a thyroid cancer is found when the patient or the patient's health care professional feels (palpates) a lump or nodule in the lower front of the neck where the thyroid is located. It is most often painless and found incidentally, by chance. Occasionally, an enlarged lymph node may be palpated by itself in the more lateral neck or in addition to a thyroid nodule.
Most patients have normal thyroid function at the time the nodule is discovered and have no symptoms related to hyper or hypothyroidism.
It the tumor grows locally, it may cause difficulty swallowing food (dysphagia) if it compresses the esophagus (which is rare) or hoarseness if the recurrent laryngeal nerve that is located near the thyroid gland -- which controls the vocal cords -- is invaded and causes vocal cord paralysis.
What are thyroid nodules?
A thyroid nodule is an abnormal growth found within the thyroid gland. It may be solid, fluid filled (cystic) -- usually with a jelly like substance called colloid -- or a combination of both.
Most often nodules are found incidentally when the patient or health care professional feels the neck. Whether the nodule is benign or cancerous cannot necessarily be determined just by feeling it and further tests may be warranted.
What are the different types of thyroid cancer?
Thyroid cancers are classified based upon which cell type is involved.
Well differentiated cancers (in which thyroid cells are less abnormal looking) include:
- Papillary thyroid cancer: This is the most common type of thyroid cancer accounting for 80% of cases.
- Hurthle cell carcinoma: This is a rare variant of papillary cancer (also known as oncocytic carcinoma).
- Follicular thyroid cancer: This is the second most common type of thyroid cancer accounding for 10% of cases.
- Medullary thyroid cancer: This thyroid cancer type arises from the C cells in the thyroid and comprises 5% of all cases.
- Anaplastic thyroid cancer: This rare cancer involves thyroid cells are very abnormal looking, accounting for 1% of all cases.
- Lymphoma: This rare cancer is most often non-Hodgkin's B cell type.
- Sarcoma: This type of thyroid cancer is very rare.
How is thyroid cancer diagnosed?
Once a lump in the thyroid is discovered, it is important to know whether it is benign or malignant (cancerous).
Often an ultrasound is performed to assess whether there is a single nodule or multiple nodules are present. Ultrasound can determine whether the nodule is fluid filled or solid. Ultrasound also can determine the general appearance of thyroid looking for inflammation or irregularities and the presence of enlarged lymph nodes nearby that may represent metastatic cancer.
Fine needle aspiration biopsy is the procedure performed to obtain a sample of cells from the nodule to determine if it is cancerous. Using ultrasound, a thin needle is placed into the nodule and cells from the nodule are obtained. These cells can be examined under a microscope by a pathologist to determine whether a cancer is present and if so, what type of cancer it is.
Results of the aspiration are usually reported as the following:
- Malignant: risk of malignancy is 100%
- Suspicious for malignancy: risk of malignancy is 50% to 75%
- Follicular cancer: risk of malignancy is 20% to 30%
- Atypical cells of unknown significance: risk of malignancy is 5% to 10%
- Benign: risk of malignancy is less than 1%
Sometimes, the results of the aspiration are unclear and indeterminate, and the aspiration may need to be repeated to get a better sample and more cells to study.
Another test involves ingesting radioactive iodine, which is taken up by the thyroid gland. The gland is scanned by a Geiger counter-type of apparatus that determines how much radioactive iodine has been taken up by the gland and any thyroid nodules. If the nodule picks up much of the iodine, it is referred to as a "hot nodule." Such nodules are rarely cancerous. Nodules that take up little to no iodine are referred to as "cold nodules." Although the overwhelming majority of such nodules are benign, 5% turn out to be malignant. Although thyroid scans may be helpful, aspiration of the gland is a much more useful test.
Blood tests may be ordered to determine thyroid hormone levels and levels of other hormones and electrolytes, like calcium, within the body. These tests indicate whether the cells of the thyroid produce too much or too little hormone, not if cancer is present.
On occasion CT, MRI, or PET scans may be useful in evaluating the neck structures if there is concern that thyroid cancer has spread (metastasized).
How is thyroid cancer staging determined?
Thyroid cancer, like most others, is staged based upon three criteria:
- T = how large the main tumor is when it is found
- N = the presence of cancer in lymph nodes and their location
- M = whether the cancer has spread or metastasized to other parts of the body. Thyroid cancer has been known to spread locally or to distant parts of the body including lungs and bone.
Staging from I to IV, including subgroups, is different for each type of cancer and helps predict outcome and survival. There are also different staging considerations for patients older or younger than age 45 for papillary and follicular thyroid cancers.
What kinds of specialists treat thyroid cancer?
A variety of physicians may be involved in the evaluation, diagnosis, and treatment of thyroid cancer. Primary care professionals may help coordinate care and may be the persons who make the initial diagnosis of thyroid gland abnormalities. Endocrinologists are specialists who specifically care for the thyroid. Surgeons may operate on the thyroid gland and thyroid cancer; these may be general surgeons or those with special training in head and neck surgery. Interventional radiologists may help with aspiration to obtain tissue samples, but this is also frequently performed by endocrinologists. Radiation oncologists, who are trained to provide radiation therapy treatments, may occasionally be asked to provide treatment. The care of thyroid cancer requires a team approach, but the members vary depending upon geographic location and availability of specialists.
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