Clinicopathological characteristics and long-term outcome in patients with distant metastases from differentiated thyroid cancer

Abstract

Background: Distant metastases are seen in a minority of patients with differentiated thyroid carcinoma (DTC) but account for most of its disease-specific mortality. Studies on the long-term outcome of patients with distant metastases are controversial.

Materials and methods: We retrospectively reviewed the medical records of 660 patients with differentiated thyroid carcinoma followed at our institution from 1994 to 2004. Forty-four patients (6.7%) had distant metastases, with a prevalence of 4.8% for papillary thyroid cancer, 21% for follicular thyroid cancer, and 10% for Hurthle cell cancer. Primary near-total thyroidectomy followed by I(131) radiation was performed in 97% of patients with metastases (86% operated on in 1980-2003). Mean age at thyroidectomy was 49+/-19 years, and the female-to-male ratio was 1.9:1.

Results: The distant metastasis occurred synchronously with the primary tumor in 45.5% and after a median follow-up of 9 years in the others. Affected sites were lungs (n=24), bones (n=11), lungs and bones (n=9), brain (n=3), and uterus (n=1). Median duration of follow-up was 12 years (range: 1-42 years) from thyroidectomy and 5.5 years (range: 1-24 years) from diagnosis of distant metastases. The 5- and 10-year survival rates (all causes) after diagnosis of distant metastases were 88% and 77%, respectively. No significant differences in survival curves were found by age, sex, metastasis site, histopathology, or interval to distant metastasis.

Conclusions: We conclude that complete resection of the thyroid gland at diagnosis and high-dose adjuvant radioactive iodine are associated with improved survival in patients with metastatic DTC.