A Series Of Studies On The Relationship Between Tg, TgAb And Thyroid Papillary Carcinoma

Differentiated thyroid cancer (DTC), including papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma, is the most common thyroid malignancy and Characterized by low malignant and good prognosis. Surgery, including isotope therapy, endocrine therapy and chemotherapy are recognized as the best treatment of DTC. Thyroglobulin (Tg) related to thyroid hormone synthesis and storage is an important indicator of follow-up of patients with DTC. The presence of thyroglobulin antibodies (TgAb) affect the detection of Tg, since they may cause Tg levels were underestimated or overestimated. In this study, the predictive value of pre-ablative stimulated Tg in distant metastasis of PTC and the time for disappearance of TgAb and influencing factors were investigatedPart I:Predictive value of pre-ablation stimulated Tg in distant metastasis of papillary thyroid cancerObjective:Recent studies have shown that Tg is a useful tumor marker in follow-up of DTC patients after thyroidectomy and subsequent radioiodine (131I) therapy. However, its role is controversial after total thyroidectomy before the first131I ablative treatment. So we investigate the predictive value of pre-ablative stimulated Tg in distant metastasis of PTC.Methods:The study included231patients with PTC who had undergone a total thyroidectomy and subsequent131I therapy. Patients were divided into two groups as M1and MO according to whether the patient present with or without distant metastasis. Student’s t-test and χ2-test were used to test for the global hypothesis of no significant difference between the two groups. Tg value between MO and M1was compared by Mann-Whitney rank-sum test. The receiver operating characteristic curves (ROC) and diagnostic critical point (DCP) were analyzed to evaluate predictive value of stimulated Tg.Results:There was no significant difference between the two groups in age (t=-0.675,p=0.50) and sex(x2=1.02,p=0.31). Pre-ablative stimulated Tg was significantly different between the two groups [the Mann-Whitney rank-sum test:p<0.0001(z=-7.648)]. The area under ROC for Tg level was0.893(95%CI:0.823-0.962). DCP of Tg was determined at52.75μg/L with sensitivity of78.90%and specificity of91.70%. Conclusion:Stimulated Tg could be a useful "diagnostic tumor marker" for metastatic PTC before the first131I ablative therapy. The DCP of Tg level is52.75μg/L, and distant metastasis of PTC should be suspected when Tg level was higher than52.75μg/L before the first131I ablative treatment.Part II:The time for disappearance of TgAb and influencing factors in patients with papillary thyroid cancerObjective:TgAb is an important part of the follow up in PTC patients with positive TgAb after radioiodine (131I) ablative therapy, persistence or increase in the serum TgAb concentration may be regarded as a marker of persistent disease. The purpose of this study was to investigate the time for disappearance of TgAb and influencing factors.Methods:The retrospective study included64patients with PTC who had undergone a total thyroidectomy and subsequent131I therapy. Patients were divided into two groups as2and1according to whether the patient present with or without concurrent Hashimoto thyroiditis (HT). TgAb1(TgAb levels determined before131I therapy) were all above the normal measuring range. The method of survival analysis (including Life tables and Cox Regression analysis) was used to assess the time to achieve disappearance of TgAb and influence factors.Results:Median time for disappearance of TgAb were9.0months and10.4months for group1and2respectively (p=0.923). Results of Cox Regression about the potential influencing factors were:TgAbl (partial regression coefficient (B)=-0.004, p=0.001), Age(B=-0.018,p=0.362), Sex(B=0.644,p=0.320), HD(B=0.341,p=0.372), which indicated that only TgAbl is relevant to TgAb negative conversion time.Conclusion:TgAbl was the potential influencing factor of the time to achieve disappearance of positive TgAb in patients with PTC. Patients with a higher TgAb need longer time to achieve disappearance of TgAb.