Background: Whether thyroidectomy for metastases to the thyroid is associated with a survival benefit remains debatable; in general, palliation and disease control are accepted goals in this setting. We evaluated the clinical features and overall survival of patients with thyroid metastasis treated by thyroid resection or nonoperatively.
Methods: This retrospective analysis included 90 patients identified with metastasis to the thyroid confirmed pathologically via thyroidectomy (n = 31) or fine-needle aspiration biopsy (n = 59). Overall survival was calculated by the Kaplan-Meier method, and differences between groups were calculated by Pearson's χ (2) coefficient.
Results: The most common primary malignancies were renal cell (20%), head and neck (19%), and lung (18%). The median time from primary tumor diagnosis to thyroid metastasis diagnosis was 37.4 months (range 0-210 months). Most metastases (69%) were metachronous, and 12% were isolated. The median follow-up after diagnosis of thyroid metastasis was 11.5 months (range 0-112 months). Median overall survival was longer in thyroidectomy patients compared to the fine-needle aspiration group (34 vs. 11 months, P < 0.0001). Patients with renal cell primary tumors were more likely to undergo thyroidectomy than patients with other primary tumors (78 vs. 24%, P < 0.0001). Nearly all patients with lung primary tumors died within 24 months of thyroid metastasis diagnosis, and thyroidectomy was only offered to three patients.
Conclusions: Thyroidectomy was safe for selected patients with metastatic disease to the thyroid. Patients with metachronous or renal cell metastasis to the thyroid and whose primary tumor is/was treatable may be appropriate candidates for resection. Lung cancer metastasis to the thyroid is generally an ominous sign.