Anaplastic thyroid carcinoma: risk factors and outcome.

Anaplastic thyroid carcinoma, in contrast to well-differentiated thyroid carcinoma, has a dismal prognosis, and little progress has been made in improving survival for this disease. We reviewed our experience during a 23-year period to identify risk factors and possible methods to improve outcome. Between 1966 and 1989, 340 patients with thyroid carcinoma underwent operation. Of these, 17 (5%) were undergoing operative treatment of anaplastic or undifferentiated thyroid carcinoma. The female/male ratio was 3.5:1, and mean age at presentation was 63 years. The most common presenting symptoms included neck mass, voice change, or dysphagia. Unusual presentations included symptomatic bradycardia from compression of the vagus nerve and superior vena cava syndrome. Four patients had a history of well-differentiated thyroid carcinoma. Nine patients had been diagnosed or treated in the past for "goiter" or a neck mass, and four patients had concurrent differentiated thyroid carcinoma associated with the anaplastic tumor. Thus 13 (76%) of 17 patients had a previous thyroid disorder, benign or differentiated malignant, and eight (47%) of 17 patients had previous or concurrent differentiated thyroid carcinoma. At the time of presentation, six patients had unilateral true vocal cord paralysis. At operation, 14 patients had local extension of the tumor and four required tracheostomy. Only five of 12 patients showed response to postoperative radiation therapy. Overall median survival was 12 months, and 13 (76%) of 17 patients died. The two patients alive longer than 12 months had only small foci of anaplastic carcinoma in association with well-differentiated carcinoma. Anaplastic thyroid carcinoma is a locally and systemically aggressive disease, with long-term survival seen only in those with well-localized anaplastic tumor. The major risk factor in this series is a history of previous benign or malignant thyroid disease. Because of this, a more aggressive approach to thyroid masses may be warranted. Long-standing goiters or benign nodules should be followed carefully and considered for resection if they grow or do not respond to medical therapy, and total thyroidectomy for malignant disease may obviate the subsequent development of anaplastic carcinoma. This method of early diagnosis and resection of abnormal thyroid tissue seems to be the only method currently available to improve the nearly uniform fatality of this disease.