Purpose: Metastatic thyroid tumors (MTT) are rare and have a poor prognosis. The aim of this retrospective study was to determine the diagnostic features and clinical outcomes of MTT.
Methods: The study subjects comprised 29 patients (age range, 37-78 years) diagnosed with MTT and treated during a 22-year period between 1987 and 2008 at a single tertiary oncology referral center.
Results: The primary cancer was breast cancer in 10 patients, lung cancer in six, digestive tract in six, kidney in three, head and neck in three and sarcoma in one patient. In seven patients, the diagnoses of primary cancer and MTT were synchronous. In 22 patients, the mean latency between the diagnosis of the primary cancer and MTT was 66 months (range 7 months-16 years). Based on ultrasonography (US), MTTs were classified into two categories: diffuse type (DT) (n = 9) and nodular type (NT) (n = 18). Eight patients who underwent thyroid surgery showed no survival benefit, but none needed tracheostomy.
Conclusions: MTT should be considered for patients with a history of malignant disease. The findings from US are useful to diagnose MTT. Careful preoperative evaluation can avoid unnecessary thyroidectomy.