Follicular thyroid carcinoma with distant metastasis: outcome and prognostic factor.

Follicular thyroid carcinoma (FTC) usually has a good prognosis unless there is distant metastasis (DM). In this retrospective study we evaluated the outcome of FTC patients with DM and attempted to identify prognostic factors. The subjects of this study were the 106 of FTC patients who underwent thyroidectomy at our hospital between 1989 and 2010 who had been diagnosed with DM at presentation or had developed DM after the initial surgery. Their cumulative cause-specific survival (CSS) rate from diagnosis of DM to date of last follow-up was calculated by the Kaplan-Meier method. Prognostic factors were identified by univariate analysis (the log-rank test) and multivariate analysis (Cox's proportional hazards model). The site of the DM was the lung in 36 patients, bone in 33 patients, both lung and bone in 28 patients and other sites in 9 patients. During the follow-up period, 22 patients died of their disease. The DMs were treated by radioactive iodine (RI) therapy in 80 patients, by surgical treatment in 36 patients and by external beam radiation therapy (EBRT) in 27 patients. The CSS rates at 5, 10, and 15 years after the first DM was diagnosed were 82.2%, 63.8%, and 23.9%, respectively. Univariate analyses and multivariate analysis identified age at diagnosis of DM and primary tumor size as significant factors related to CSS. In this study, we could not show RI therapy, EBRT or surgical treatment for DM had an impact on the outcome.