Variables predicting distant metastases in thyroid cancer.

Objectives: Distant metastases from thyroid cancer are uncommon and have a variable prognosis. We present a series of patients with distant metastases to determine which patients are at risk of developing distant disease and to examine the significant prognostic variables.

Study Design: Retrospective chart review of 30 patients with distant metastases compared with 633 controls from the Mount Sinai Thyroid Cancer Database and literature review.

Methods: The prevalence of distant metastases was 4.5%, and median follow-up of survivors was 12.7 years. Histologic type was Hurthle cell carcinoma in 3, follicular in 3, papillary in 19, and 5 patients had focal anaplasia either in the primary site or regional metastases. Predictors for distant metastases, locoregional control, and survival were analyzed.

Results: Cumulative survival for patients with distant metastases was 49.5% at 10 years and 12.9% at 20 years. Site of metastases was lung in 26, bone in 11 and brain in 1 patient, with 8 patients having multiple sites. The median time to diagnosis of distant metastases was 3 months. Variables that predicted for development of distant disease were male sex, age, size, extrathyroidal extension, regional metastases, and elevated thyroglobulin. Survival in patients without distant disease was significantly better than those with distant metastases (P < .001). Variables that predicted poor outcome in patients with distant metastases on analysis were age greater than 45 years (P = .003) and histologic type of thyroid cancer (P = .009).

Conclusion: Although patients with thyroid cancer and distant metastases may live prolonged periods with disease, it does significantly impact on patient survival. Age remains an important variable in both predicting for development of distant metastases and also influences long-term survival in patients with existing distant metastases.