In spite of its rich vasculature, the thyroid gland is rarely the site of metastatic disease. The incidence of such metastases differs depending on the type of the analyzed material. In clinical papers, the incidence is low and, according to various sources, amounts to 2-3% of all malignant tumors of the thyroid. Most commonly, the primary tumor is located in the breast, bronchi, gastrointestinal system, (the colon, esophagus, or stomach) and kidneys. Usually, metastatic thyroid disease is identified upon autopsy, and only sporadic cases are encountered in clinical material. The authors present their experience in treating metastatic disease involving the thyroid gland based on the analysis of their clinical material consisting of patients operated on in a single center.
Seventeen patients presented with metastatic tumors of the thyroid. The material was further analyzed retrospectively. The group included four men and 13 women, with the male to female ratio of 1:4.25. The age of the patients ranged from 46 to 76 years, with the mean age amounting to 62+/-9.78 years. Eleven patients were diagnosed based on fine needle aspiration biopsy (FNAB).
In 13 patients, the primary lesion was a clear cell carcinoma of the kidney, in one breast cancer, in another one uterine carcinoma. In two patients, no primary focus location was established. All the patients were treated surgically. Twelve patients were consistently followed up after the surgery. Of this group, seven are still alive, including five individuals with metastases of renal carcinomas, but without recurrent disease. Five patients died due to disseminated neoplastic disease. No data are available on three patients. The mean follow-up time after thyroid surgery was 3.9 years. The longest followed-up survival time was 11 years.
The most commonly clinically detected and treated surgically metastatic lesion of the thyroid gland is clear cell cancer of the kidney. In cases of renal cancer metastases to the thyroid gland, a total thyroidectomy seems to be warranted, although it does not affect the survival time.