Thyroid cancer
Thyroid cancer: Excerpt from Professional Guide to Diseases (Eighth Edition)
Papillary and follicular carcinomas are the most common types of thyroid cancer and are usually associated with a longer 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 E 2 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, anaplastic tumors resist radiation and metastasize rapidly.
Causes and incidence
Predisposing factors to thyroid cancer include radiation exposure (especially childhood radiation therapy), prolonged thyroid-stimulating hormone (TSH) stimulation (through radiation or heredity), familial predisposition, or chronic goiter.
Thyroid cancer occurs in all age-groups, especially in people who have had radiation treatment of the neck area. It affects 1 in 1,000 people.
Signs and symptoms
The primary signs of thyroid cancer are a painless nodule, a hard nodule in an enlarged thyroid gland, or palpable lymph nodes with thyroid enlargement. Eventually, the pressure of such a nodule or enlargement causes hoarseness, dysphagia, dyspnea, and pain on palpation. If the tumor is large enough to destroy the gland, hypothyroidism follows, with its typical symptoms of low metabolism (mental apathy and sensitivity to cold). However, if the tumor stimulates excess thyroid hormone production, it induces symptoms of hyperthyroidism (sensitivity to heat, restlessness, and hyperactivity). Other clinical features include diarrhea, anorexia, irritability, vocal cord paralysis, and symptoms of distant metastasis.
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 much 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 scinti-scan 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. (See Staging thyroid cancer.)
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 (131I) 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 TSH production, and simultaneous administration of an adrenergic blocking agent such as propranolol, increasing tolerance to surgery and radiation
❑Chemotherapy for symptom-producing, widespread metastasis is limited, but doxorubicin is sometimes beneficial.
Special considerations
Before surgery, tell the patient to expect temporary voice loss or hoarseness lasting several days after surgery.
Plan meticulous postoperative care:
❑When the patient regains consciousness, keep him in semi-Fowler's position, with his head neither hyperextended nor flexed, to avoid pressure on the suture line. Support his head and neck with sandbags and pillows; when you move him, continue this support with your hands.
❑After monitoring vital signs, check the patient's dressing, neck, and back for bleeding. If he complains that the dressing feels tight, loosen it and call the physician immediately. Check serum calcium levels daily; hypocalcemia may develop if parathyroid glands are removed. Watch for and report other complications: hemorrhage and shock (elevated pulse rate and hypotension), tetany (carpopedal spasm, twitching, and seizures), thyroid storm (high fever, severe tachycardia, delirium, dehydration, and extreme irritability), and respiratory obstruction (dyspnea, crowing respirations, retraction of neck tissues). (See What happens in thyroid storm, page 70.)
❑Keep a tracheotomy set and oxygen equipment handy in case of respiratory obstruction. Use continuous steam inhalation in the patient's room until his chest is clear.
❑The patient may need I.V. fluids or a soft diet, but many patients can tolerate a regular diet within 24 hours of surgery.
Care of the patient after extensive tumor and node excision is identical to other radical neck postoperative care. Referral to a local or national support group can help relieve the patient's stress.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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