Abstract:
Objective To investigate the predictive value of postoperative initial stimulated thyroglobulin(ps-Tg) level on the distant metastasis of differentiated thyroid carcinoma(DTC).
Methods A total of 113 patients who suffered from DTC and underwent first radioactive iodine(RAI) therapy from August 2016 to August 2017 were identified. Of these patients, 32 were males and 81 were females. Their ages ranged from 15 years to 68 years (44.85±12.01 years). The patients were classified into a non-distant metastasis(M0) group and a distant metastasis(M1) group. The biochemical parameters of thyroid function and thyroid antibodies were evaluated after 4 weeks of levothyroxine withdrawal. After RAI therapy, whole body imaging and local SPECT/CT were performed. The basic data of the two groups were compared via a chi-square test, Student's t test, and a Mann-Whitney rank-sum test. ps-Tg values between M0 and M1 were also compared via the Mann-Whitney rank-sum test. An receiver operating characteristic(ROC) curve was drawn and analyzed to evaluate the predictive value of ps-Tg, and a diagnostic critical point(DCP) was obtained.
Results Differences in pathological type, cervical lymph node metastasis, and RAI dose were observed between M0(85 cases) and M1(28 cases) (χ2=12.588, 12.588, 12.581; P=0.003, 0.003, 0.002). No significant differences were found in gender, age, tumor stage, and time from surgery to the first measurement of Tg, TSH, and TgAb between the two groups. The mean values M(P25~P75) of ps-Tg levels in the two groups were 1.95(0.70–6.98) and 95.05 (6.98–278.47) ng/mL. A significant difference was present between the two groups(U=417.5, P=0.000). The area under the ROC curve of ps-Tg levels was 0.825(95%CI: 0.713–0.936), with a sensitivity of 71.4%, a specificity of 91.8%, and an accuracy of 86.7%. The cut-off value of DCP was 28.80 ng/mL.
Conclusion The initial ps-Tg level is a meaningful indicator for predicting the distant metastases of DTC.