METASTASIS TO THE THYROID-GLAND - A REPORT OF 43 CASES

BACKGROUND. The incidence of metastasis to the thyroid gland in autops y series varies from 1.25% to 24%. Metastasis to the thyroid gland is usually: considered a terminal event, and the effectiveness of convent ional treatment has been questioned. The authors assessed the effects of current methods of diagnosis and treatment on the course of the dis ease. METHODS. Forty-three patients with metastasis to the thyroid gla nd were studied retrospectively. Primary tumor origin was identified i n all but two cases. Metastasis to tile thyroid gland was confirmed by fine-needle aspiration cytology or histology. Data were analyzed for the frequency and types of malignant lesions, the clinical course of d isease, and the prognosis after thyroid involvement. RESULTS. The kidn ey was the most common primary tumor site (33%), followed by lung (16% ), breast (16%), esophagus (9%), and uterus (7%). The time from diagno sis of the primary tumor to metastasis to the thyroid gland was consid erable for renal cell adenocarcinoma (mean, 106 months) and fur adenoc arcinomas of the breast (mean, 131 months) and uterus (mean, 132 month s), In 12 patients, this interval was more than 120 months. Fine-needl e aspiration cytology; detected metastatic malignancy in 29 of 30 pati ents. Treatment involved surgery alone, surgery with adjuvant therapy, or nonsurgical methods, Two patients with uterine adenocarcinoma and one with breast adenocarcinoma had disease regression with no evidence of tumor recurrence. CONCLUSIONS. In any patient with a previous hist ory of malignancy no matter how remote that history is, a new thyroid mass should be considered recurrent malignancy until proved otherwise. Although detection of metastasis to the thyroid gland often indicates poor prognosis, aggressive surgical and medical therapy may be effect ive in a small percentage of patients. (C) 1997 American Cancer Societ y.