Thyroid

Head and Neck Cancer Introduction Page
oral cavity
oropharynx
(soft palate, tonsil, base of tongue)
larynx (voice box)
hypopharynx (pyriform sinus, posterior phanryngeal wall, post-cricoid region)
nasal cavity/paranasal sinuses
nasopharynx
salivary glands
paragangliomas (glomus tumors)
thyroid


Thyroid

Background
Signs and Symptoms
Clinical Evaluation
Treatment
Follow-Up

Background



The thyroid gland is located in the lower part of the neck and has two lobes, one on each side of the trachea (windpipe). It produces a hormone called thyroxin that controls our metabolism, which is the rate at which we burn energy.

Signs and Symptoms

The thyroid gland may be enlarged (goiter) for many reasons, most often by non-cancerous conditions. Women are more likely than men to develop an enlarged thyroid.

Prior exposure to radiation, especially during childhood, will increase the risk of developing cancerous thyroid tumors. The most common malignancy is papillary carcinoma and this represents the least aggressive of the malignant thyroid tumors. The other types of malignant thyroid tumors (in decreasing order of occurrence) are follicular, medullary, and anaplastic. Medullary tumors may have a heredity link. Anaplastic carcinoma usually occurs in older patients, frequently with a long history of a thyroid mass.

Diagnosis and treatment of thyroid cancer usually begins when the patient notices a growth in his/her thyroid gland, or a physician notes it during a physical examination. Except for anaplastic carcinoma, thyroid tumors are usually slow growing, and they rarely cause pain. Thyroid tumors may cause a hoarse voice if they involve the adjacent nerve going to the vocal cords. The larger tumors may cause difficulty breathing or swallowing if they compress or invade the trachea or esophagus. The lymph nodes of the neck may also become noticeable if they become involved by tumor.

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Clinical Evaluation

The physician will perform a thorough history and physical examination. It should be noted if there has been any prior radiation exposure or if family members have had thyroid tumors. The vocal cord motion will be evaluated with an endoscopy. An endoscopy, often done in the doctor’s office, involves placing a small, flexible instrument through the nose in order to see all the structures of the throat. The procedure is painless. A fine needle aspiration biopsy, which involves inserting a small needle into the mass and withdrawing cells, will help to establish the type of tumor. The pathologist examines these cells under a microscope to see if they are cancerous. Blood tests, ultrasound examinations (sonograms), radioisotope studies, CT scans (which use X-rays to create a two-dimensional image of the area), or MRI scans (which use a magnetic field and pulses of radio wave energy to visualize the detailed anatomy), may be performed to evaluate the tumor.

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Treatment

Thyroid cancers are initially treated with surgery to removal all or almost all of the thyroid gland with any involved lymph nodes. Patients will require postoperative thyroid hormone pills. If there are any adjacent structures in the neck involved with tumor (e.g. trachea, muscles), they may have to also be removed. Sometimes, thyroid tumors with more extensive soft tissue involvement (such as with anaplastic thyroid carcinoma) may not be totally removed.

The excellent prognosis with most thyroid tumors (especially papillary carcinoma) is due to postoperative treatment with radioactive iodine treatment, which is administered by pills. This treatment specifically targets thyroid tumor cells, no matter where they may be in the body. If tumors are more resistant to this therapy, radiation therapy may be administered.

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Follow-Up

Periodic physical examination is necessary after treatment. Patients are maintained on thyroid pill hormone replacement. Blood tests (thyroglobulin levels or calcitonin levels in medullary carcinoma) may indicate the status of recurrent tumor.

Radioisotope studies, ultrasound exams and CT or MRI scans will evaluate the status of tumor recurrence.

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