Long-Term Outcomes of Patients with Papillary Thyroid Cancer Undergoing Remnant Ablation with 30 milliCuries Radioiodine.

Abstract

The study considered the long-term outcome of patients with papillary thyroid carcinoma treated with 30 mCi radioiodine. The aims of this study were to define and compare the remission rates of papillary thyroid carcinoma ablated with 30 mCi (131)I prepared by either thyroid hormone withdrawal (THW) or recombinant human thyrotropin (rhTSH; Thyrogen(®)), and to identify variables predictive of a favorable prognosis. An observational study was conducted at an academic medical center and a comparative summary of six studies is presented. Three hundred and seventy patients (THW group, n = 203; rhTSH group, n = 167) were recruited from a prospectively managed registry. The mean follow-up was 9.3 years (range 5.1-15.8 years) in the THW group and 7.1 years (range 5.0-9.7 years) in the rhTSH group. The primary endpoint was the long-term remission rates (no evidence of disease) in the THW group compared with the rhTH group. The response at 12-18 months after 30 mCi remnant ablation was excellent in 79.3% and 76.0% of patients in the THW group and the rhTSH group, respectively (p > 0.05). The long-term remission rates also did not significantly differ between both groups at 95.6% and 97.0%. Although the surveillance period for the THW group exceeded that of the rhTSH group, no significant difference in recurrence-free survival was discerned by the Kaplan-Meier curves. In a multivariate analysis, an excellent response to therapy at 12-18 months correlated significantly with long-term remission rates in the THW group (p = 0.031, odds ratio [OR] = 2.6 [confidence interval (CI) 1.1-6.0]), the rhTSH group (p = 0.03, OR = 5.3 [CI 1.2-23.8]), and the pooled groups (p = 0.001, OR = 3.43 [CI 1.63-7.2]). The pre-ablation thyroglobulin level significantly correlated with remission rates only in the THW group (p = 0.035, OR = 5.5 [CI 1.1-27.1]). The response to remnant ablation with 30 mCi radioiodine is often excellent, and the long-term remission rates can be expected to be high, independent of the method of delivery (i.e., THW or rhTSH).