Longer-term recurrence rate after low versus high dose radioiodine ablation for differentiated thyroid Cancer in low and intermediate risk patients: a meta-analysis.

BACKGROUND Regarding the longer-term recurrence rate the optimal activity for the remnant thyroid ablation in patients with differentiated thyroid cancer (DTC) is discussed controversially. For the short-term ablation success rate up to 12 months there are already several meta-analyses. In this study we performed the first meta-analysis regarding the longer-term recurrence rate after radioactive 131-I administration. METHODS We conducted an electronic search using PubMed/MEDLINE, EMBASE and the Cochrane Library. All randomized controlled trials (RCTs) assessed the recurrence rate after radioactive iodine ablation in patients with DTC, with a follow-up of at least two years were selected. Statistics were performed by using Review Manager version 5.3 and Stata software. RESULTS Four RCTs were included in the study, involving 1501 patients. There was no indication for heterogeneity (I2 = 0%) and publication bias. The recurrence rate among patients who had a low dose 131-iodine ablation was not higher than for a high dose activity (odds ratio (OR) 0.93 [95% confidence interval (CI) 0.53-1.63]; P = 0.79). The mean follow-up time was between 4.25 and 10 years. The subgroup analysis regarding the TSH stimulated thyroglobulin values (< 10 ng/mL versus < 2 ng/mL versus ≤1 ng/mL) showed no influence on recurrence rate. CONCLUSIONS For the first time we showed that the longer-term, at least 2-year follow-up, recurrence rate among patients who had 131-iodine ablation with 1.1 GBq was not higher than with 3.7 GBq.