The Role Of Thyroglobulin In The Supervision And Response-Prediction In Differentiated Thyroid Cancer

Thyroglobulin（Tg）concentration is a useful tumor marker in long-term follow-up of differentiated thyroid cancer（DTC）patients after thyroidectomy and subsequent radioiodine(¹³¹I)therapy.The study aims at its role in the supervision and response-prediction in non-metastatic DTC,and further evaluation of Tg negative conversion short after ¹³¹I therapy was conducted in low-to-intermediate-recurrence DTC.The study has two parts as follows.PART 1.Response to ¹³¹I Therapy in Non-metastatic Differentiated Thyroid Cancer（DTC）Patients with Preablation Stimulated Thyroglobulin（ps-Tg）above 10ng/mlObjectrive To evaluate the response of ¹³¹I therapy and to explore the influencing factors in non-metastatic DTC patients with ps-Tg above 10ng/ml.Methods The study included 157 DTC patients who had undergone total or near-total thyroidectomy and subsequent ¹³¹I therapy with ps-Tg>10ng/ml,and they were divided into 3 groups as ER（49 cases）AR（36 cases）and IR（72 cases）according to the response after ¹³¹I therapy.We compared the clinical pathologic features and ps-Tg levels among 3 groups,as well as ps-Tg levels between IR and non-IR groups.The ROC curve was employed to evaluate the predictive value of the ps-Tg level in ¹³¹I therapy responses.Results The 3 groups showed significant differences in ps-Tg levels（H=35.142,P<0.001）,gender（χ2=6.82,P=0.033）,extrathyroid invasion（H=31.380,P<0.001）and lymph node metastases（H=14.375,P=0.001）.The ps-Tg level in IR is higher than it in non-IR（U=1384.5,P<0.001）,while it was not significantly different between ER and AR（U=771.5,P=0.326）.The diagnostic critical point（DCP）of ps-Tg to differentiate IR and non-IR is 28.3ng/ml（sensitivity 57.5%,specificity 87.1%）,with a corresponding area under the ROC curve（AUC）0.774（95%CI:0.701～0.847）.Conclusions Near-half（45.86%）non-metastatic DTC patients with ps-Tg above 10ng/ml showed more tendency to be IR.The level of ps-Tg>28.3ng/ml may be a useful and sensitive diagnostic boundary value for predicting incomplete response.PART 2.Serial Thyrogiobulln Varying Trend Short After ¹³¹I Therapy in Low-to-intermediate-rrecurrence Differentiated Thyroid CancerObjective To dynamically observe the varying trend of Tg levels short after ¹³¹I therapy in low-to-intermediate-recurrence DTC patients.Methods The study enrolled 78 post-total-thyroidectomy DTC patients and they were stratified as low-to-intermediate recurrence according to the ATA guidelines.Clinical data including ps-Tg,the corresponding TSH,TgAb values and the afterwards parameters were dynamically measured each week in the first month after ¹³¹I therapy.Values collected at the first time were defined as TgO and TSHO,while Tg1 and TSH1 were collected at the first week after ¹³¹I respectively.Then the varying trend curves of Tg were drawn,and factors influencing the variation of Tg were analyzed.Two groups were divided according to Tg levels:G1（Tg4≤0.1ng/ml,n=35）,G2（Tg4>0.1 ng/ml,n=43）.Results The rates of negative Tg were 3.8%、14.1%、21.8%、30.8%、44.9%respectively,right before ¹³¹I therapy and the 1st,2nd,3rd and 4th week after therapy.One-way analysis of variance showed that the two groups statistically differed in age（P=0.032）and remnant thyroid（P=0.025）.Multivariate logistic regression analysis showed that early negative Tg was related to remnant thyroid tissue（P=0.008）.Conclusions Negative Tg can be achieved in near-half of DTC patients by the end of the first month after ¹³¹I therapy.The negative conversion is closely related with the volume of remnant thyroid tissue.