Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Cancer, Thyroid Gland


Related Terms

  • Anaplastic Carcinoma
  • Cancer of the Thyroid
  • Follicular Carcinoma
  • Hürthle Cell Cancer
  • Malignant Lymphoma of the Thyroid
  • Medullary Carcinoma
  • Papillary Carcinoma
  • Thyroid Cancer

Differential Diagnosis

Specialists

  • Endocrinologist
  • General Surgeon
  • Oncologist
  • Otolaryngologist
  • Radiology Oncologist
  • Thyroid Surgeon

Factors Influencing Duration

The age of the individual with thyroid cancer may affect disability. Generally, older individuals do not recover from this condition as easily as do younger individuals. The type of thyroid cancer, the stage of the disease, the presence and extent of metastasis, and the method of treatment also may influence the length of disability. If radiation or chemotherapy is used following surgery, a longer period of disability may be expected.

Medical Codes

ICD-9-CM:
193 - Cancer, Thyroid Gland
237.4 - Other and Unspecified Endocrine Glands; Parathyroid Gland; Thyroid Gland
239.7 - Neoplasm of Unspecified Nature, Endocrine Glands and Other Parts of Nervous System

Overview

Thyroid cancer is a malignant tumor that develops in the tissue of the thyroid gland. The thyroid gland is an endocrine gland located at the base of the neck that produces hormones (thyroxine, calcitonin) that helps regulate the body's metabolism. Most thyroid cancers present as a small mass (nodule) of regular or irregular shape. Single or multiple nodules may be present. Although 90% to 95% of nodules of the thyroid are noncancerous (benign) ("Detailed Guide"), four main types of malignant thyroid tumors are described based on the cells from which they arise. They include: papillary (80% of thyroid cancers), follicular (10%), medullary (5% to 10%), and anaplastic (1% to 2%) thyroid carcinomas (Sharma). Papillary and follicular carcinomas (together referred to as differentiated thyroid cancer [DTC]) comprise 80% to 90% of all thyroid cancers ("Detailed Guide"). The cell of origin in papillary, follicular, and anaplastic carcinomas is the follicular cell in the thyroid endoderm.

Papillary carcinoma, also called papillary cancer or papillary adenocarcinoma is by far the most common type of thyroid cancer. Eighty to ninety percent of the time papillary cancer tumors develop in only 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 can occur in any part of the thyroid and form tumors 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 to the lymph tissue in the neck (cervical lymph nodes) than papillary cancer but is 20% more likely than papillary to spread via the bloodstream to the bones, lungs, liver, and brain (Sharma).

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 cervical lymph nodes and other organ systems.

The cell of origin in medullary carcinoma or medullary thyroid cancer (MTC) is a calcitonin-producing "C" cell derived from neuroendocrine tissue. MTC accounts for 5% to 10% of all thyroid carcinomas (Sharma). The growth rate of medullary carcinomas varies widely. Two types of MTC are described. 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 MTC ("Detailed Guide").

Hürthle cell cancer is a rare thyroid cancer that is characterized by large, polygonal follicular cells with granular cytoplasm. These cells are also found in benign thyroid conditions such as Hashimoto's thyroiditis and Graves' disease. In thyroid cancer, the Hürthle cells make up from 75% to 100% of the tumor (Sharma). This rare cancer accounts for 2% to 3% of thyroid malignancies, occurs more often in women, and is diagnosed typically between ages 50 and 60 (Sharma). Progression can be aggressive and rapid.
When clinical and diagnostic evaluation is complete, thyroid cancer is staged according to its size and degree of invasiveness. Staging is essential in determining treatment and predicting outcome for each individual. The staging system used is based on characteristics of the tumor, lymph nodes, and metastasis (TNM). This incremental staging system can be generalized in numerical grouped stages I through IV, in which the higher the assigned number, the greater the extent of invasion of tissue outside the thyroid. Thyroid cancer stages by type are described 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 invaded tissue outside the thyroid gland but has not spread farther than local lymph nodes in the neck region. Stage IV, cancer has spread to distant sites through the lymphatic or circulatory system, possibly invading the spine, other bones, lungs, liver, and brain.

All anaplastic cancers are considered stage IV because they are so rapidly invasive.

Incidence and Prevalence: Thyroid cancer constitutes about 1% of all malignant tumors (Sharma). In the US, the American Cancer Society estimated that about 44,670 individuals would be newly diagnosed with thyroid cancer in 2010, affecting about 33,930 women and 10,740 men, with 1,690 deaths (“Detailed Guide”).

Although international incidence statistics are not available for all countries, thyroid cancer is more prevalent in landlocked, underdeveloped countries where there is little iodine in the diet.

Source: Medical Disability Advisor



Causation and Known Risk Factors

Age and gender are the most predictive risk factors for developing thyroid cancer. Most papillary and follicular thyroid cancers are diagnosed in individuals between the ages of 20 and 60 years (“Detailed Guide”). The likelihood of recurrence is increased if the diagnosis is first made before age 20 or after age 60 (Sharma). Women develop papillary tumors 3 times as often as men, with a mean age at diagnosis of 34 to 40 years (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 MTC appear to run in families as the result of inheriting an abnormal gene. Familial medullary thyroid carcinoma (FMTC) represents about 1 in 5 MTCs. It can be found alone or in combination with other types of tumors (“Detailed Guide”). Multiple endocrine neoplasia type 2 (MEN2) is an inherited MTC that appears with tumors of other endocrine glands such as the adrenal glands or parathyroid glands. It can also be associated with pheochromocytomas (MEN2b). These inherited thyroid cancers develop in children or young adults and are known to spread aggressively and early (“Detailed Guide”).

Source: Medical Disability Advisor



Diagnosis

History: Individuals with thyroid cancer usually report a single, firm, nontender 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 the laryngeal nerve or vocal cords (larynx) and difficulty swallowing (dysphagia) or breathing (dyspnea) due to pressure on the throat (esophagus) or wind pipe (trachea), respectively. If the tumor has metastasized, the individual may report respiratory difficulties, cough, blood in the sputum (hemoptysis), chest pain, and musculoskeletal problems such as bone pain. A report of recent weight loss may signal metastasis of the tumor. A family history of thyroid cancer may be reported.

Physical exam: A complete head and neck examination is performed with special attention given to the thyroid gland and cervical lymph nodes. Manipulation with the fingers (palpation) may reveal a single, firm, nontender, symmetric, or asymmetric nodule at the base of the neck. Firm, hard, or fixed nodules are more indicative of malignancy than softer, mobile nodules. More advanced thyroid tumors may be large, or they may have many nodules (multinodular). Often they are firmly attached to adjacent structures in the neck. Enlarged cervical lymph nodes or a firm cervical mass may be present if the tumor is advanced.

Tests: Blood tests will include thyroid function tests such as measurement of calcitonin and thyroxine in response to stimulation of the thyroid gland. An elevated calcitonin level suggests MTC. Serum thyroid-stimulating hormone (TSH) is also measured. Low values suggest a benign tumor. Polymerase chain reaction (PCR) assays are considered sensitive for mutations in regulator genes (oncogenes) associated with thyroid cancer.

Ultrasound is the favored imaging modality for evaluating thyroid disease. It is able to provide accurate information but is unlikely to be conclusive in terms of malignancy. Other imaging tests may include x-ray, computed tomography (CT), and magnetic resonance imaging (MRI) scans to visualize the tumor and surrounding soft tissue.

Thyroid nodules also can be visualized through radioactive imaging using a radioisotope (either radiolabeled iodine-123, 131-I, or 99Tcm pertechnetate) to determine the functional status of the nodule. After the individual has swallowed or been injected with a radioisotope, images of the thyroid are captured on a specialized (gamma) camera or with positron emission tomography (PET) scans. The radioisotope is delivered to the thyroid via the bloodstream. Well-differentiated cancerous nodules are sensitive to TSH and takes up the radioisotope, as does healthy thyroid tissue. Nonfunctional nodules do not take up the isotope and appear “cold” (non-radioactive) in images. Hyperfunctional nodules take up the radioisotope and appear “hot” in images (hot nodules), indicating possible malignancy. The results of this test allow determination of the size of the nodule but may not confirm or exclude malignancy. Accordingly, this test is more often used to evaluate thyroid function than to assess for malignancy. After thyroidectomy, this technique may be used to determine whether thyroid cancer has spread to other parts of the body.

A definitive diagnosis of thyroid cancer is made by obtaining a tissue sample (biopsy) from the nodule using fine needle aspiration biopsy (FNAB). Cells are aspirated through a needle inserted into the suspicious mass. The cells are then examined in the laboratory by a cytologist (histopathologic examination) to determine if the nodule is cancerous. Four results are possible with FNAB: benign disease, malignant disease, indeterminate diagnosis, and non-diagnosis (normal). The majority of tumors (69%) are benign and no further tests are done, 4% are malignant and surgery is indicated, 10% are indeterminate and will be watched, and 17% are nondiagnostic and also will be rechecked periodically (Sharma).

Source: Medical Disability Advisor



Treatment

Surgery to remove part or all of the thyroid gland (partial or total thyroidectomy, respectively) is the primary treatment. If the cancer has spread to the lymphatic system, some lymph nodes may need to be removed (lymphadenectomy). After thyroidectomy, radioisotope imaging is performed to assess for regional or distant metastases and radioactive iodine therapy (radioiodine ablation) may be used to destroy any residual cancer cells. Radiation therapy 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 sometimes is used in conjunction with radiation therapy. When a cure is not possible, radiation therapy may be used as palliative treatment.

In rare cases, if an individual with stage I or II cancer is at low risk for recurrence or metastases, the cancerous thyroid lobe is removed along with the midportion of the thyroid (thyroid lobectomy with isthmectomy) as the only treatment.

An individual with well-differentiated thyroid cancer who has had thyroidectomy and radioiodine ablation may be maintained on suppression of TSH production by the pituitary gland. Suppression is achieved by taking daily doses of thyroxine (T4). Keeping a low level of TSH reduces recurrent tumor growth in these patients.

Loss of thyroid tissue after surgery or radiation treatment may result in decreased production of thyroid hormones (thyroxine and calcitonin), and hormonal supplements may be needed for lifetime maintenance.

Source: Medical Disability Advisor



Prognosis

The predicted outcome depends on the type, size, and stage of thyroid cancer at diagnosis. The age of the individual at diagnosis also is an important prognostic factor in all types of thyroid cancers. Individuals who are older than 40 years at diagnosis have a poorer prognosis, with higher morbidity and mortality rates; those diagnosed before age 20 or after age 60 have a greater likelihood of recurrence (Sharma).

The overall five-year survival rate for all types of thyroid cancer is about 97% (“Detailed Guide”). The 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: 45%. 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: 78%; stage IV: 24%. All anaplastic thyroid cancer is considered stage IV and has a 5-year survival rate of only 9% (“Detailed Guide”). Anaplastic carcinoma of the thyroid is the most aggressive of all thyroid cancers, and progression is rapid. Despite treatment most individuals die within a year from airway obstruction or complications of lung metastasis (Sharma).

Hürthle cell carcinoma has a 5-year survival rate of 50% to 60%. It is aggressive and requires careful monitoring for metastatic disease (Sharma).

Source: Medical Disability Advisor



Rehabilitation

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). Early respiratory therapy may help to prevent the individual from developing alternative respiratory strategies due to incisional discomfort, such as shallow breathing.

If total thyroidectomy is performed, damage to the laryngeal nerve that innervates the vocal cords is probable, resulting in difficulty speaking (dysphonia), 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 be necessary if the cancer had metastasized and part of the tongue or lower jaw was surgically removed. Therapy also may be needed to restore normal swallowing in individuals who develop dysphagia.

Source: Medical Disability Advisor



Complications

MTC can produce high concentrations of various chemical secretions (serotonin, prostaglandins, calcitonin, histamine, vasoactive peptide) that affect other organ systems. Typically, an individual will exhibit flushing and diarrhea in response to these factors. Anaplastic cancer grows very rapidly and can lead to dysphagia, dyspnea, and dysphonia. Metastasis into lymph 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 veins (superior vena cava) that returns blood to the heart.

Common complications following total thyroidectomy are laryngeal nerve injury and hypoparathyroidism from damage to or removal of the parathyroid glands.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Radiation therapy and chemotherapy may cause fatigue and will limit the capacity of the individual to perform heavy labor upon return to work, thus requiring reassignment to a sedentary position with minimal physical labor until recovery is complete.

Source: Medical Disability Advisor



Failure to Recover

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?
  • Has individual been repeatedly exposed to external radiation?
  • Does individual have low intake of dietary iodide?
  • Is a firm, nontender nodule(s) present at the base of the neck?
  • Does individual complain of hoarseness, dysphonia, dysphagia, dyspnea, hemoptysis, chest pain, or bone pain?
  • Were thyroid function tests performed? Polymerase chain reaction assay?
  • Was ultrasound imaging done? CT? MRI?
  • Was radioisotope imaging performed?
  • Was FNAB done to confirm the diagnosis?
  • Was a diagnosis of papillary, follicular, medullary, or anaplastic thyroid cancer?
  • What was the stage of the cancer at diagnosis?
  • Has the thyroid cancer metastasized to cervical lymph nodes or other organ systems?

Regarding treatment:

  • Was partial or total thyroidectomy or thyroid lobectomy performed?
  • Had cancer spread to the cervical lymph nodes? If so, were they removed (lymphadenectomy)?
  • Did individual receive radioactive iodine ablation to destroy residual cancer cells?
  • Was postoperative radioisotope imaging performed to assess for regional or distant metastases?
  • Did individual require radiation therapy? Chemotherapy?
  • Does individual require lifetime thyroid hormone supplements?

Regarding prognosis:

  • Is individual being monitored for metastases?
  • Have any complications developed after surgery, such as laryngeal nerve injury or hypoparathyroidism? Are they being treated? Responding to treatment?
  • Is employer able to accommodate individual's return to work?
  • If individual has anaplastic cancer, what is the expected survival time?
  • Would individual benefit from any form of additional treatment at this time?

Source: Medical Disability Advisor



References

Cited

American Cancer Society. "Detailed Guide: Thyroid Cancer." American Cancer Society. 5 May. 2009. 2 Oct. 2009 <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. 27 Apr. 2007. Medscape. 2 Oct. 2009 <http://emedicine.medscape.com/article/851968-overview>.

Source: Medical Disability Advisor






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