Long-term follow-up of patients with bone metastases from differentiated thyroid carcinoma -- surgery or conventional therapy?

OBJECTIVE: Surgery of bone metastases from differentiated thyroid carcinoma seems indicated in individual patients. This study was performed (1) to analyse retrospectively patients with bone metastases from differentiated thyroid carcinoma and (2) to evaluate the impact of surgery of bone metastases on survival. PATIENTS AND
DESIGN: We analysed 41 consecutive patients with bone metastases from differentiated thyroid carcinoma who had undergone thyroid surgery at Vienna University Hospital since 1966. The median follow-up time was 12 years. There were 24 females and 17 males with a mean age of 60 +/- 12 years. Primary tumour histology was follicular in 35 and papillary in six patients. Radioiodine treatment was performed in 32 with a mean administered activity of 27 +/- 24 GBq 131I. Metastases restricted to the skeleton were found in 22 whereas in 19 individuals additional extraskeletal distant metastases were seen. Twenty-seven patients had multiple bone metastases. In 21 individuals, up to five bone metastases were surgically removed with the intention of cure.
RESULTS: Univariate analysis identified total thyroidectomy (P = 0.003), lymph node surgery (P = 0.001), radioiodine therapy (P = 0.036), and the absence of extraskeletal distant metastases (P = 0.017) as significant predictors of survival. Multivariate analysis failed to identify significant prognostic factors. In the subgroup of patients with distant metastases limited to the bones, univariate analysis identified, in addition to thyroid and lymph node surgery, the surgical extirpation of the bone metastases as a significant prognostic factor associated with improved survival (P = 0.025).
CONCLUSIONS: These findings indicate that in patients without additional extraskeletal distant metastases, the radical surgical extirpation of bone metastases from differentiated thyroid carcinoma might be associated with improved survival.