| Objective:To evaluate the efficacy and recurrence rate of different doses of 131I for remnant ablation in low-and intermediate-risk differentiated thyroid cancer by meta-analysis.Methods:PubMed,EMbase,The Cochrane Library,Web of Science,VIP,WanFang Data,CNKI,CBM databases were electronically searched to collect randomized controlled trials(RCTs)on the efficacy and recurrence rate of radioiodine therapy with various levels of activity(low-dose:1110 plus or minus 370MBq;moderate-dose:1850plus or minus 370MBq;high-dose:3700plus or minus 370MBq)in low-and intermediate-riskdifferentiated thyroid cancer from inception to October 2019.After screening studies,extracting data and evaluating the quality of selected studies by using the RCT risk assessment tool recommended by the Cochrane handbook 5.1.0,meta-analysis was performed by using RevMan 5.3 software.P values of less than 0.05 were considered significant.Risk ratio(RR)was used as the effect analysis statistics and the corresponding 95%CI were also calculated.Heterogeneity was assessed using chi-square and I2 statistics.If there was significant heterogeneity between included studies,the method as subgroup analysis,sensitivity analysis or descriptive analysis would be used.Results:1.Twelve RCTs involving 2655 patientswere included in accordance with the inclusion and exclusion criteria.Low-dose group involved 1102 patients;moderate-dose group involved 377 patients;and high-dose group involved 1176 patients.2.The analysis of ablation success rate:(1)There was no statistical significance in the ablation success rate between low and high radioiodine dose[RR=0.91,95%CI(0.81,1.01),P=0.08].In subgroup analysis,ablation success rates using low-dose were similar to high-dose in Europe subgroup[RR=0.97,95%CI(0.92,1.01),P=0.11],Asian subgroup[RR=0.79,95%CI(0.57,1.11),P=0.18],lymph node metastasis sub-group[RR=0.96,95%CI(0.92,1.01),P=0.08],no lymph node metastasis subgroup[RR=0.86,95%CI(0.62,1.19),P=0.36],low iodine diet subgroup[RR=0.88,95%CI(0.72,1.09),P=0.26],no low iodine diet subgroup[RR=0.92,95%CI(0.83,1.03),P=0.14],THW(thyroid hormone withdrawal)subgroup[RR=0.88,95%CI(0.71,1.08),P=0.21],THW/rhTSH(recombinant human thyroid stimulating hormone)subgroup[RR=0.97,95%CI(0.93,1.01),P=0.11],99mTc subgroup[RR=0.96,95%CI(0.89,1.03)P=0.24],and 131I less than or equal to 74MBq subgroup[RR=0.96,95%CI(0.87,1.07),P=0.45].But the rate of successful ablation of low-dose 131I group was lower than high-dose 131I group when using 131I>74MBq in diagnostic scan before ablation[RR=0.61,95%CI(0.49,0.76),P<0.00001].(2)The moderate-versus high-dose groupshowed no significant differencesin the ablation success rate[RR=0.96,95%CI(0.89,1.03),P=0.23].(3)The low-versus moderate-dosegroupshowed no significant differencesin the ablation success rate[RR=0.96,95%CI(0.87,1.06),P=0.41].3.The analysis of recurrence rate:There was no statistical significance in the recurrence rate between low and high radioiodine dose[RR=1.01,95%CI(0.63,1.62),P=0.96]and also between moderate and high radioiodine dose.Conclusion:1.The ablation success rate of different doses of 131I for remnant ablation was similar in low-and intermediate-risk differentiated thyroid cancer,and the recurrence rate in follow-up also showed no significant differences.Low-dose radioiodine(1110MBq)is sufficient for postoperative remnant ablation in patients with low-and intermediate-risk differentiated thyroid cancer.2.It may have an effect on the efficacy of postoperative remnant ablationwith low-dose(1110MBq)131I that using 131I for diagnostic scan before ablation.However,more evidences will be needed. |
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