Efficacy and prognosis after different doses of ¹³¹I treatment for differentiated thyroid cancer in low- and intermediate-risk patients: a Meta-analysis

Objective To evaluate the short-term efficacy and long-term prognosis of patients with low- and intermediate-risk differentiated thyroid cancer (DTC) treated with different ¹³¹I doses.

Methods Studies on the short-term efficacy and long-term prognosis evaluation of patients with DTC after ¹³¹I treatment were searched from databases such as PubMed, EMBASE, Cochrane Library, CNKI, and Wanfang from inception to September 2022. Screening of literature was based on specific inclusion and exclusion criteria. Meta-analysis was performed with RevMan 5.4 software. Dichotomous data were compared using relative risk (RR), and 95% confidence intervals (95%CI) were calculated for each estimate. Heterogeneity was evaluated by χ² test and I² value.

Results Seven studies with 2754 patients were included. The low-dose group (1.1–2.2 GBq) comprised 1452 cases, and the high-dose group (3.7 GBq) consisted of 1302 cases. (1) No significant difference in short-term efficacy (RR=0.93, 95%CI: 0.86–1.01, P=0.07) was found between the low- and high-dose groups. Further analysis showed no statistically significant difference between the subgroups of regions (Europe (RR=0.95, 95%CI: 0.90–1.01, P=0.08) and Asia (RR=0.86, 95%CI: 0.68–1.08, P=0.20)); operation modes(total thyroidectomy (RR=0.78, 95%CI: 0.49–1.23, P=0.28); and near total thyroidectomy (RR=0.97, 95%CI: 0.93–1.01, P=0.15)); risk stratification (low and intermediate risk (RR=0.92, 95%CI: 0.83–1.01, P=0.08); and low risk (RR=0.98, 95%CI: 0.83–1.14, P=0.76)); thyroid-stimulating hormone (TSH) stimulation modes (thyroid hormone withdrawal (RR=0.90, 95%CI: 0.79–1.02, P=0.11); and thyroid hormone withdrawal/recombinant human TSH (RR=0.96, 95%CI: 0.90–1.03, P=0.23)); and criteria for successful ablation (Tg<10 ng/ml (RR=0.94, 95%CI: 0.86–1.03, P=0.20), Tg<2 ng/ml (RR=0.85, 95%CI: 0.68–1.05, P=0.13), and Tg<1 ng/ml (RR=0.96, 95%CI: 0.84–1.11, P=0.61)). (2)No significant difference in long-term prognosis was observed between the low- and high-dose groups (RR=0.93, 95%CI: 0.58–1.49, P=0.77). Further analysis showed no statistically significant difference between the subgroups of operation modes (total thyroidectomy (RR=1.09, 95%CI: 0.28–4.21, P=0.80); and near total thyroidectomy (RR=0.88, 95%CI: 0.52–1.50, P=0.63)); risk stratification (low and intermediate risk (RR=2.00, 95%CI: 0.50–7.94, P=0.32); and low risk (RR=0.83, 95%CI: 0.50–1.37, P=0.46)); and follow-up time (<5 years (RR=0.45, 95%CI: 0.10–2.02, P=0.30), ≥5 years (RR=1.03, 95%CI: 0.60–1.75, P=0.93), <10 years (RR=1.00, 95%CI: 0.56–1.76, P=0.99), and ≥10 years (RR=0.80, 95%CI: 0.35–1.82, P=0.54)). (3) Significant difference in subsequent ¹³¹I treatment was found between the low- and high-dose groups (RR=1.61, 95%CI: 1.33–1.95, P<0.001).

Conclusions No statistically significant difference in short-term efficacy and long-term prognosis was observed between low- and high-dose ¹³¹I treatments for low- and intermediate-risk DTC. Patients treated with low-dose ¹³¹I are likely to undergo ≥ 2 times of ¹³¹I treatment due to residual thyroid or persistent/recurrent diseases.