Purpose: Previous reports have suggested that metastatic tumors to the thyroid gland are rare, with a poor prognosis, but many of their clinicopathological characteristics are still to be revealed. Herein, our clinical experiences are reviewed.
Methods: The medical records for all patients pathologically diagnosed with metastatic tumors to the thyroid gland, between January 1986 and June 2003 at the Seoul National University Hospital were reviewed. The cases of direct invasion from adjacent tissues, and lymphoma or leukemia involving the thyroid gland, were excluded. The clinicopathological characteristics and survival rate of 11 eligible patients were evaluated.
Results: The incidence rate of all the malignant thyroid tumors was 0.43%. The mean age at diagnosis was 44.75±11.73 (33~6) years, and the male to female ratio was 4 : 7. The most common presenting symptom was a neck mass (n=7). The common primary tumor sites were the lung (n=3) and breast (n=2). The mean follow-up period was 5.17±4.71, ranging from 0 to 13 months. Six of the ten patients that could be followed-up, died within 16 months. The females (P=0.04), some primary cancer sites, such as the breast, kidney and lung (P=0.04), and those having undergone a thyroidectomy (P=0.01) showed better survival rates.
Conclusion: The incidence of metastatic tumors to the thyroid gland was very rare, and those tumors showed a very poor prognosis. There were various primary tumor sites, but the lung and breast were relatively more common. The females and some primary cancer sites, such as the breast, kidney and lung, showed better survival rates. Active surgical treatment might lead to a better prognosis.
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