Tg levels in differentiated thyroid cancer patients with intermediate or low risk of recurrence after 131I therapy / 中华核医学与分子影像杂志

ABSTRACT

Objective To investigate the change of serum Tg levels of DTC patients with positive stimulated Tg (Tg ≥ 10.00 μg/L),negative 131I-diagnostic whole body scan(Dx-WBS) and no distant metastasis 6 months after initial 131I therapy.Methods Fifty-six DTC patients (20 males,36 females,average age 43.11 (21-70) y) with intermediate or low risk of recurrence according to American Thyroid Association (ATA) guideline were enrolled into the retrospective study.All patients were grouped according to stimulated Tg level after initial 131I therapygroup with positive Tg (Tg+ group,n =19) and group with negative Tg (Tgˉ group,n=37).Changes of suppressed Tg at 1 year and 2.5 years (Tg1ysup and Tg2.5ysup) after initial therapy were compared between the two groups.Serum TSH level,TgAb level,neck ultrasound and chest CT results were also evaluated.The two-sample t test and x2 test were used for statistical analysis with SPSS 17.0.Results Stimulated Tg and Tglysup levels in Tg+ group were remarkably higher than those in Tgˉ group(24.27±4.10) μg/L vs (2.73±3.01) μg/L,t=7.191,P＜0.05(6 months after initial 131I therapy) ; (2.21±0.55) vs (0.48±0.10) μg/L,t=3.102,P＜0.05(1 year after initial 131I therapy),respectively.In Tg+ group,suppressed Tg level decreased with time in 68.4％ (13/19) of patients,of whom the Tg2.5ysup level was much lower than Tglysup level ((0.53±0.15) μg/L vs (1.38±0.50) μg/L).Tg2.5sup level in Tg+ group became comparable to that in Tgˉ group ((1.44±0.52) μg/L vs (0.38±0.07) μg/L; t =2.001,P＞0.05).In each group,one case of recurrence with suppressed Tg of 1.4 μg/L and 0.1 μg/L respectively,was observed using neck ultrasound after 2 years of follow-up.Conclusions Serum Tg levels decreased with time for Tg+/131I-Dx-WBS-DTC patients with intermediate or low risk of recurrence.It might not be necessary to follow up these patients with Tg and 131 I-DxWBS after 6 months of initial 131I therapy.