Therapy Response And Prognosis Among Of Different Doses Of¹³¹I For Low-and Intermediate-risk Differentiated Thyroid Carcinoma

PART ONE:Therapy response and progression-free survival among different doses of 131I for low-and intermediate-risk differentiated thyroid carcinomaObjective:To investigate therapy response and progression-free survival(PFS)with different doses of 131I in postoperative patients with low-and intermediate-risk differentiated thyroid carcinoma(DTC).Methods:A total of 201 DTC patients with a total of 236 person-time 131I treatments with different doses of 131I were retrospectively analyzed.They were divided into four groups(G1 to G4 group)according to 131I administered activity(1.1 GBq once,1.1 GBq twice,3.0 GBq,3.7 GBq).Serological and imaging indexes at 6 to 12 months after treatment were determined to evaluate the response of patients.Therapy response can be divided into 4 types,which is excellent response(ER),indeterminate response(IDR),biochemical incomplete response(BIR)and structural incomplete response(SIR)retrospectively.The patients were followed up for 12 to 90 months,and their serological,imaging and treatment records were collected after 131I therapy to assess the progression.Chi-square test and Fisher’s exact test were performed to compare the differences in efficacy response and influencing factors among the treatment groups.Kaplan-Meier method and log-rank test were used to compare the PFS.Cox proportional risk model was used to evaluate the independent risk factors for PFS.Results:①Total rate of ER/IDR/BIR/SIR among 4 groups were 41.5%(98/236)、44.9%(106/236)、6.8%(16/236)and 6.8%(16/236)respectively.②The ER/IDR/BIR/SIR rates of G1～G4 were 16.67%(10/60)、42.86%(15/35)、56.52%(13/23)、50.85%(60/118)、60.00%(36/60)、45.71%(16/35)、30.43%(7/23)、39.83%(47/118)、10.00%(6/60)、0%(0/35)、4.35%(1/23)、7.63%(9/118)、13.33%(8/60)、11.43%(4/35)、8.70%(2/23)、1.69%(2/118)respectively.③ There were statistically significance in the rate of excellent response(ER)between G1 and G2/G3/G4(P=0.005;0.000;0.000)and structural incomplete response(SIR)between G1 and G4(P=0.003).④The median follow-up time was 30 months,with progression observed in 18 patients(8.96%).There were no significant differences in PFS among different doses of 131I(P=0.112).Multivariate analysis showed that age(<55 years)and therapy response(ER)were independent prognostic factors for PFS.Conclusions:The short-term ablation efficacy of 131I between multiple low-dose(1.1 GBq twice)group and high-dose(3.0&3.7 GBq)groups has no significant difference in postoperative patients with low-and intermediate-risk DTC.Different doses of 131I are not significantly related to PFS.For patients with ER and aged<55 years,there is a PFS benefit.PART TWO:Efficacy and recurrence after radioiodine ablation for differentiated thyroid cancer in low and intermediate risk patients:a meta-analysisObjective:To evaluate the efficacy and long-term recurrence of different radioactive iodine(RAI)activities in low-and intermediate-risk differentiated thyroid cancer(DTC).Methods:We conducted an electronic search using PubMed/MEDLINE,EMBASE,the Cochrane Library,CNKI,WanFang Data form inception to September 2022.All randomized clinical trials(RCTs)evaluating patients with low-and intermediate-risk DTC who were treated initially with total/near-total thyroidectomy,followed by different doses of RAI ablation with at least 12 months were selected.The meta-analysis was performed using RevMan version 5.4.Dichotomous data were compared using a relative ratio(RR),and 95%confidence intervals(CI)were calculated for each estimate.We determined heterogeneity by visual inspection of forest plots and using the χ2 test and I2 statistic.A fixed-effects model was used for calculations unless significant heterogeneity existed(I2>50%),in which case a random-effects model was used.A P value of<0.05 was considered statistically significant.When we found heterogeneity,we attempted to determine potential reasons for it by examining individual study and subgroup characteristics.Results:Seven studies with a total of 2754 patients were eventually included.There were 1452 cases in low-dose group(1.1～2.2 GBq)and 1302 cases in high-dose group(3.7 GBq).There was no difference in successful remnant ablation(RR,0.93;95%CI,0.86-1.01;P=0.07)between low-activity and high-activity RAI.Compared with high acticitiy,lowdose treatment has similar effect in regions[Europe(RR,0.96;95%CI,0.90-1.02;P=0.19);Asia(RR,0.86;95%CI,0.68-1.08;P=0.20)],operation modes[TT(RR,0.78;95%CI,0.59-1.23;P=0.28);NTT(RR,0.97;95%CI 0.93-1.01;P=0.14)],risk stratification[low and intermediate risk(RR,0.92;95%CI,0.83-1.01;P=0.08);low risk(RR,0.98;95%CI,0.83-1.14;P=0.76)],TSH stimulation modes[THW(RR,0.90;95%CI,0.791.02;P=0.11);THW/rhTSH(RR,0.97;95%CI,0.89-1.05;P=0.41)]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,0.80;95%CI,0.72-1.05;P=0.90);Tg<1 ng/ml(RR,0.97;95%CI,0.84-1.11;P=0.62)].There was no significant difference in successful remnant ablation(RR,0.93;95%CI,0.58-1.49;P=0.77)between low-activity and high-activity RAI.The subgroup analysis,regarding the operation modes[TT(RR,1.09;95%CI,0.28-4.21;P=0.90);NTT(RR,0.88;95%CI,0.52-1.50;P=0.6)]，risk stratification[low and intermediate risk(RR,2.00;95%CI,0.50-7.94;P=0.32);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),≥ 10 years(RR,0.80;95%CI,0.35-1.82;P=0.54)],showed no influence on recurrence rate.Conclusions:There was no difference between low-dose and high-dose 131I in the ablation success rate and long-term recurrence rate in low and intermediate risk DTC.Patients treated with low dose RAI were more likely to receive≥ 2 times of RAIT for persistent or recurrent diseases.