| Thyroid cancer is a tumor that develops in the tissue of the thyroid gland, which is located at the base of the neck and regulates body's metabolism. Most thyroid cancers present as a small mass of regular or irregular shape (nodule). There may be either single or multiple nodules. Although 90% to 95% of nodules and tumors of the thyroid are benign ("Detailed Guide"), there are four main types of thyroid cancer: papillary, follicular, medullary, and anaplastic thyroid carcinomas. Papillary and follicular carcinomas (together referred to as differentiated thyroid cancer, or DTC) comprise 80% to 90% of all thyroid cancers ("Detailed Guide").
Papillary carcinoma, also called papillary cancer or papillary adenocarcinoma, develops from thyroid follicle cells. Eighty to ninety percent of the time, these tumors develop only in one lobe of the thyroid ("Detailed Guide"). Tumors vary in size from microscopic to several centimeters in diameter. These are slow-growing cancers that may spread (metastasize) to lymph nodes.
Follicular carcinoma, also called follicular cancer, is the second most common type of thyroid cancer. This cancer may occur in any part of the thyroid and in a wide variety of sizes. These tumors are well defined when small, but as they enlarge, they may invade both the blood vessels and outer covering (capsule) of the thyroid. Follicular cancer is less likely to metastasize than papillary cancer but may spread via the bloodstream to the bones, lungs, liver, and brain.
Medullary carcinoma accounts for about 5% of all thyroid carcinomas ("Detailed Guide"). The growth rate of medullary carcinomas varies widely. There appear to be two types of medullary cancer. Sporadic medullary carcinoma develops mainly in older adults and is not inherited. Familial medullary thyroid cancer appears to be inherited. It accounts for up to 20% of cases of this type of thyroid cancer ("Detailed Guide").
Anaplastic carcinoma, also called undifferentiated thyroid cancer, is an uncommon, aggressive type of thyroid cancer that accounts for 1% to 2% of thyroid carcinoma (Sharma). Anaplastic carcinoma is thought to develop from papillary or follicular cancer cells. This type of thyroid cancer is very invasive, spreading rapidly to the neck and other parts of the body.
A general summary of the staging of thyroid cancer is as follows:
Papillary and follicular cancer for individuals under age 45: stage I, cancer has not spread to distant sites; stage II, cancer has spread to distant sites.
Papillary and follicular cancer for individuals over age 45 and medullary thyroid cancer for all ages: stage I, tumors less than 2 cm. Cancer has not spread to local lymph nodes or distant sites. Stage II, tumors are 2 to 4 cm. Cancer has not spread to local lymph nodes or distant sites. Stage III, tumors are larger than 4 cm. Cancer has grown outside thyroid gland but has not spread farther than local neck nodes. Stage IV, cancer has spread to distant sites or grown into neck, spine, or large blood vessels.
All anaplastic cancers are considered stage IV, because they are so rapidly invasive.Risk: Age is the most predictive risk factor for individuals developing thyroid cancer. Most thyroid cancer is diagnosed in individuals between the ages of 30 and 50 ("Detailed Guide"). The likelihood of recurrence is increased if the first diagnosis is made before age 20 or after age 60; 3 times as many new cases are diagnosed in women as in men (Sharma). Other factors that may increase the risk of developing thyroid cancer are a diet low in iodine and exposure to radiation during childhood and adolescence. Some types of medullary thyroid carcinomas appear to run in families as the result of inheriting an abnormal gene. Incidence and Prevalence: Thyroid cancer constitutes about 1% of all malignant tumors. In the US, the American Cancer Society estimates that about 23,600 individuals will be diagnosed with thyroid cancer in 2004. Annually, 1,460 people die from the disease ("Detailed Guide"). Although international incidence statistics are not available, thyroid cancer is more prevalent in landlocked, underdeveloped countries where there is little iodine in the diet. |
Source: Medical Disability Advisor
| History: Individuals with thyroid cancer usually report a single, firm, nontender lump (nodule) at the base of the neck. If the tumor is pressing on other structures in the neck, symptoms may include hoarseness or loss of voice from pressure on nerves in the vocal chord (larynx) and difficulty swallowing or breathing due to pressure on the throat (esophagus) or wind pipe (trachea), respectively. If the tumor has spread (metastasized), the individual may report respiratory difficulties, cough, blood in the sputum (hemoptysis), chest pain, and musculoskeletal problems such as bone pain. Physical exam: Manipulation with the fingers (palpation) may reveal a single, firm, nontender, symmetric, or asymmetric mass (nodule) at the base of the neck. Occasionally, the thyroid will appear perfectly normal despite the presence of a cancerous growth. More advanced thyroid tumors may be larger, or they may have many nodules (multinodular). Often, they are firmly attached to adjacent structures in the neck. Enlarged lymph nodes may be present if the tumor is advanced. Metastasis of the tumor may result in weight loss. Tests: Thyroid nodules can be visualized through the use of a radioisotope (131I or 99Tcm pertechnetate). After the individual has swallowed (or been injected with) the radioisotope, images of the thyroid are captured on a specialized (gamma) camera. Only the thyroid tissue takes up the radioisotope. The results of this test allow determination of the size of the tumor and whether it has spread to other parts of the body. Other tests may include x-ray, CT and MRI imaging scans, high-frequency sound waves (ultrasound) to visualize the tumor, and measurement of thyroid hormones (calcitonin and thyroxin) in response to stimulation of the thyroid gland (thyroid function tests). However, a definitive diagnosis for thyroid cancer can only be made by obtaining a tissue sample (biopsy) from the nodule. Biopsies are obtained by aspirating cells through a needle inserted into the suspicious mass (fine needle aspiration biopsy, or FNAB). Biopsy tissue is then used to determine if the nodule is cancerous. |
Source: Medical Disability Advisor
| Surgery to remove part or all of the thyroid gland (partial or total thyroidectomy, respectively) is the most common treatment. If the cancer has spread into the lymphatic system, some lymph nodes may need to be removed (lymphadenectomy). Following surgery, radioactive iodine can be administered orally or by injection to destroy any residual cancer that may be left behind (radioactive iodine therapy). X-rays from an external source (external beam radiotherapy) may be used to treat larger, well-defined residual tumors. This treatment usually continues 5 days a week for about 6 weeks. Chemotherapy is sometimes used in conjunction with radiation therapy.
Loss of thyroid tissue after surgery or radiation treatment may result in decreased production of thyroid hormones (thyroxin and calcitonin), and hormonal supplements may be needed for lifetime maintenance. |
Source: Medical Disability Advisor
| The predicted outcome depends on the type and stage of thyroid cancer. The age of the individual at diagnosis is an important factor in all types of thyroid cancers. Younger people have a better prognosis than do the elderly. Five-year survival rates for papillary carcinoma as estimated by the American Cancer Society are as follows: stages I and II: 100%; stage III: 96%; stage IV: 57%. For follicular cancer, the rates are stage I and II: 100%; stage III: 79%; stage IV: 47%. For medullary thyroid cancer, the rates are as follows: stage I: 100%; stage II: 97%; stage III: 79%; stage IV: 24%. All anaplastic thyroid cancer is considered stage IV and has a 5-year survival rate of only 9% ("Detailed Guide"). |
Source: Medical Disability Advisor
| If treatment for thyroid cancer requires a thyroidectomy, the individual will not be allowed to participate in an exercise program until swelling in the area of the incision is significantly lessened (2 to 3 weeks). Respiratory therapy may help initially to prevent the individual from developing alternative strategies, such as shallow breathing, due to incisional discomfort.
If total thyroidectomy is performed, damage to the recurrent nerve that enervates the vocal chords is probable, resulting in hoarseness or weakness in voice. The individual will undergo an assessment of vocal production and be taught how to coordinate breathing and speaking for maximal vocal production. Speech therapy may also be necessary if the thyroid cancer metastasized and part of the tongue or lower jaw was surgically removed. |
Source: Medical Disability Advisor
| Medullary carcinomas can produce high concentrations of various chemical secretions (serotonin, prostaglandins, calcitonin, histamine, vasoactive peptide) that affect the circulatory system. Typically, an individual will exhibit flushing and diarrhea in response to these factors. Anaplastic cancer grows very rapidly and can lead to difficulty in swallowing (dysphagia), breathing (dyspnea), and speaking (dysphonia). Metastasis into nodes and distant organs occurs in most of cases of anaplastic cancer. Anaplastic cancer tumors may become large enough to obstruct one of the major vessels (superior vena cava) that return blood to the heart. |
Source: Medical Disability Advisor
| A leave of absence for surgery, therapy, and recovery from treatments is usually required. Those treated by surgery, radiation, and chemotherapy will have a limited capacity to perform heavy labor upon return to work and will require reassignment to a sedentary position with minimal physical labor until recovery is complete. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- Does individual have a family history of thyroid cancer?
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Was individual repeatedly exposed to external radiation?
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Does individual have low intake of dietary iodide, resulting in goiter?
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Is a single, firm, nontender lump (nodule) present at the base of the neck?
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Does individual complain of hoarseness, loss of voice, or difficulty swallowing or breathing? Does individual report respiratory difficulties, cough, blood in the sputum (hemoptysis), chest pain, or bone pain, suggesting metastasis?
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Was the thyroid visualized on a gamma camera after injecting or swallowing a radioisotope? Was ultrasound done?
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Was a tissue sample (biopsy) from the thyroid obtained to confirm the diagnosis?
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Was a diagnosis of papillary, follicular, medullary, or anaplastic thyroid carcinoma confirmed?
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Has the thyroid cancer spread (metastasized) into other organ systems?
Regarding treatment:
- Was surgery done to remove part or all of the thyroid gland (partial or total thyroidectomy, respectively)?
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Did the cancer spread to the lymph nodes? If so, were they removed (lymphadenectomy)?
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Did individual receive radioactive iodine to destroy any residual cancer?
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Will individual require radiation treatments at 1 to 5 year intervals?
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Does individual require lifetime thyroid hormone (thyroxin and calcitonin) supplements?
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Would individual benefit from chemotherapy?
Regarding prognosis:
- What type of thyroid cancer does individual have?
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Did treatment begin at an early stage of the cancer?
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Is this a recurrence?
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Has the cancer spread (metastasized)?
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Has individual developed flushing and diarrhea due to high concentrations of secretions, such as serotonin, prostaglandins, calcitonin, histamine, and vasoactive peptide that affect the circulatory system?
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If individual has anaplastic cancer, what is the expected survival time?
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Source: Medical Disability Advisor
| "Detailed Guide: Thyroid Cancer." American Cancer Society. 14 Jul. 2003. 2 Oct. 2004 <http://www.cancer.org/docroot/CRI/CRI_2_3x.asp?dt=43>.Sharma, Pramod K., and Michael M. Johns. "Thyroid Cancer." eMedicine. Eds. Samia Nawaz, et al. 22 Aug. 2003. Medscape. 4 Oct. 2004 <http//emedicine.com/ent/topic646.htm>. |
Source: Medical Disability Advisor
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