Low versus high radioiodine activity to ablate the thyroid after thyroidectomy for cancer: a meta-analysis of randomized controlled trials.

It is not known whether low-dose radioiodine is as effective as high-dose radioiodine for treating patients with differentiated thyroid cancer after surgery. This study compared ablation success rates of different doses of radioiodine in patients with differentiated thyroid cancer after thyroidectomy. Fifteen randomized controlled trials were obtained from PubMed, Embase, and Cochrane Library (1966 to February 2013). Stata version 12.0 was used to pool the outcomes. Mantel-Haenszel (MH) and inverse variance (IV) methods were used in a fixed-effects and random-effects model, respectively. The relative risk (RR) with 95% confidence interval (CI) was used to compare the success rates of different doses of radioiodine. There were a total of 3,046 patients. The pooled RR for comparing ablation success with low- and high-dose radioiodine was 0.90 (95% CI 0.83-0.98, IV). Excluding a study with a distinctive outcome, sensitivity analysis showed that the pooled RR was 0.95 (95% CI 0.92-0.99, MH). In subgroup analysis, the pooled RR of three studies that only administrated radioiodine to patients with pT2-4 cancer was 0.93 (95% CI 0.83-1.04, MH); the pooled RR of five studies with total thyroidectomy for all patients was 0.96 (95% CI 0.92-1.00, MH); and the pooled RR of four studies that used thyrotropin α to stimulate serum thyrotropin was 0.96 (95% CI 0.90-1.02, MH). The pooled RRs for comparing ablation success for moderate-dose versus high-dose and low-dose radioiodine were 0.94 (95% CI 0.85-1.04, IV) and 0.87 (95% CI 0.73-1.04, IV), respectively. Low-dose radioiodine can be used in patients undergoing total thyroidectomy. For those who receive insufficient surgical treatment, high-dose radioiodine is more appropriate.