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Thyroid Cancer - Symptoms & Treatment

Cancer of the thyroid occurs in all age groups, especially in persons who have had radiation treatment to the neck area. Papillary and follicular carcinomas are most common and are usually associated with prolonged survival.

Papillary carcinoma accounts for half of all thyroid cancers in adults; it's most common in young adult females and metastasizes slowly. It's the least virulent form of thyroid cancer. Follicular carcinoma is less common but more likely to recur and metastasize to the regional nodes and through blood vessels into the bones, liver, and lungs.

Medullary carcinoma originates in the parafollicular cells derived from the last branchial pouch and contains amyloid and calcium deposits. It can produce calcitonin, histaminase, corticotropin (producing Cushing's syndrome), and prostaglandin E2 and F3 (producing diarrhea).

This rare form of thyroid cancer is familial, associated with pheochromocytoma, and completely curable when detected before it causes symptoms. Untreated, it progresses rapidly. 

Seldom curable by resection, giant and spindle cell cancer (anaplastic tumor) resists radiation and metastasizes rapidly.

The prognosis is often excellent for a cancerous thyroid nodule. The most common types of thyroid cancer can often be completely removed with surgery. But the important first step is to know the symptoms and see your doctor.

Causes

Although the exact cause of thyroid cancer has not been determined, exposure to radiation during childhood is a known risk factor for thyroid cancer. In the 1950s and 1960s, radiation was used to treat acne and to reduce swelling and infection of organs in the neck, such as the tonsils, adenoids, and lymph nodes. Recent studies prove that people who received radiation to the head and neck during their childhood have a higher than average chance of developing thyroid cancer.

Signs and symptoms

Most often, you won't have signs and symptoms in the early stages of thyroid cancer, but as the cancer grows, you may experience one or more of the following:

• A lump - sometimes growing rapidly - in the front of your neck, just below your Adam's apple
• Hoarseness or difficulty swallowing
• Trouble breathing
• Swollen lymph nodes, especially in your neck
• Pain in your throat or neck, sometimes spreading up to your ears

Having one or more of these symptoms doesn't necessarily mean you have thyroid cancer. Other conditions - including a benign thyroid nodule, an infection or inflammation of the thyroid gland, and a benign enlargement of the thyroid (goiter) - can cause similar problems, all of which are highly treatable.

Diagnosis

The first clue to thyroid cancer is usually an enlarged, palpable node in the thyroid gland, neck, lymph nodes of the neck, or vocal cords. A patient history of radiation therapy or a family history of thyroid cancer supports the diagnosis. However, tests must rule out non­malignant thyroid enlargements, which are more common.

• Thyroid scan differentiates between functional nodes (rarely malignant) and hypofunctional nodes (commonly malignant) by measuring how readily nodules trap isotopes compared with the rest of the thyroid gland. In thyroid cancer, the scintiscan shows a "cold," non­functioning nodule.
• Other tests include needle biopsy, computed tomography scan, ultrasonic scan, chest X -ray, serum alkaline phosphatase, and serum calcitonin assay to diagnose medullary cancer. Calcitonin assay is a reliable clue to silent medullary carcinoma.

Treatment

• Total or subtotal thyroidectomy, with modified node dissection (bilateral or unilateral) on the side of the primary cancer (papillary or follicular cancer)
• Total thyroidectomy and radical neck excision (for medullary, giant, or spindle cell cancer)
• Radiation with external radiation (for inoperable cancer and sometimes postoperatively in lieu of radical neck excision) or alone (for metastasis)
• Adjunctive thyroid suppression, with exogenous thyroid hormones suppressing thyrotropin production, and simultaneous administration of an adrenergic blocking agent, such as propranolol, increasing tolerance to surgery and radiation
• Chemotherapy for symptomatic, wide­spread metastasis is limited, but doxorubicin is sometimes beneficial.

Prevention

Because most people with thyroid cancer have no known risk factor, it is not possible to completely prevent this disease. However, inherited cases of medullary thyroid cancer can be prevented and radiation to the neck is avoided. If a family member has had this disease, the rest of the family can be tested and treated early. The National Cancer Institute recommends that a doctor examine anyone who has received radiation to the head and neck during childhood at intervals of one or two years. The neck and the thyroid should be carefully examined for any lumps or enlargement of the nearby lymph nodes. Ultrasound may also be used to screen for the disease in people at risk for thyroid cancer.