Preablation sTg Research Articles

Therapeutic efficacies of remnant ablation and radioiodine adjuvant therapy in differentiated thyroid cancer.

Successful ablation in 131I therapy for differentiated thyroid cancer (DTC) includes both remnant ablation (RA) and radioiodine adjuvant therapy (RAT). This study aimed to differentiate between the therapeutic efficacies of RA and RAT, investigate the factors associated with their effectiveness, and assess their impact on prognosis. This retrospective study included patients with DTC who underwent initial 131I therapy at our tertiary center. The successful RA (SRA) and successful RAT (SRAT) was determined based on the 131I-diagnostic whole-body scan (Dx-WBS), TSH-stimulated thyroglobulin (sTg) levels, and neck ultrasound at the 6th month after 131I therapy. The patients were divided into complete response and persistent/recurrent disease groups during the follow-up period. A total of 232 patients were included, 91.8% (213/232) of patients achieved SRA, only 8.1% (19/232) failed RA (FRA). Among the 213 patients in the SRA group, 70.4% (150/213) achieved SRAT and 29.6% (63/213) failed RAT (FRAT). Only pre-ablation sTg >10 ng/mL (OR = 46.968, 95% CI 9.731-226.699, P < 0.001) was an independent risk factor predicting the failure of RAT. The prognostic analysis included 215 patients, and 6.1% (13/215) were classified as persistent/recurrent disease at the last follow-up. Both pre-ablation sTg >10 ng/mL (HR = 4.765, 95% CI 1.371-16.566, P = 0.014) and FRAT (HR = 10.104, 95% CI 1.071-95.304, P = 0.043) independently predicted persistent/recurrent disease. RA is easy to achieve successfully, whereas RAT evaluation provides greater value than RA for prognosis prediction. For patients with low Tg levels and no imaging evidence of disease, routine Dx-WBS during follow-up has minimal significance.

Sufficiency of a Single Negative Thyroglobulin Standard for Judging the Success of Ablation in Low- and Intermediate-risk Differentiated Thyroid Cancer: A Retrospective Study.

We investigated how reduced successful ablation criteria may be used to evaluate radioiodine remnant ablation in patients with low- and intermediate-differentiated thyroid carcinoma (DTC). Overall, 254 low- and intermediate-risk patients with DTC were categorized into three groups (positive, weak, positive, and negative) on the basis of a visual study of thyroid imaging performed before postoperative iodine treatment. Semi-quantitative analysis parameters were incorporated into the positive Tc-99m pertechnetate scanning to further examine the clinical use of thyroid imaging. We investigated the value of successful judgment criteria and the influencing factors of radioiodine ablation. At the same time, the predictive value of thyroglobulin (Tg) for radioiodine treatment and the overall clinical efficacy were assessed. A total of 250 (98.43%) patients were identified as having functional thyroid tissue residue on the Rx-whole-body scan, and 137 (53.94%) patients had positive Tc-99m pertechnetate scans using semi-quantitative analysis. The single Tg standard could not substitute the double standard (χ2c=22.042, p<0.001) for patients with residual thyroid weight by a semiquantitative analysis. However, the semi-quantitative analysis revealed no association between 99mTcO4-thyroid scan and ablation treatment using semi-quantitative analysis; only preablation sTg levels were related with success in the multivariate logistic regression analysis, with a cut-off value of 2.88 ng/mL. The pre-ablation stimulated Tg level was also the primary factor of satisfactory response following follow-up with an optimal cut-off of 6.506 ng/mL. Even in low- and intermediate-risk patients with DTC, a single negative Tg standard also requires receiving some restrictions in the evaluation of ablation success and is inadequate. Conventional 99mTcO4 thyroid imaging combined with a quantitative analysis program can improve the clinical practice of single negative Tg standard.

Is there a role for diagnostic scans in the management of intermediate-risk thyroid cancer?

Radioiodine (RAI) is selectively recommended for intermediate-risk differentiated thyroid carcinomas (DTC). The information gleaned from pretherapy stimulated thyroglobulin levels (sTg) and diagnostic 131I whole-body scans (DxWBS) to guide therapy remains controversial. The present study aimed at evaluating the impact of preablation sTg and DxWBS in the management of intermediate-risk DTC. A retrospective analysis of 301 intermediate-risk DTC patients submitted to total thyroidectomy and RAI therapy was performed. Pretherapy sTg and DxWBS and post-therapy WBS (RxWBS) findings were analyzed and compared to outcomes. Fifty-two patients (17.3%) had metastases diagnosed by DxWBS and/or RxWBS. The DxWBS identified 10.6% of patients with functioning metastases, including unexpected distant metastases. If combined with SPECT-CT, DxWBS detected RAI-avid metastases more frequently, particularly lymph node metastases (13.1% vs 4.2% planar WBS, P = 0.015). The DxWBS findings modified patient management in 8.3%. A pretherapy sTg <1 ng/mL was associated with a low false-negative rate for the presence of metastases (5.2%), and its performance in excluding metastasis was improved by a negative DxWBS (2.7% of patients with both negative exams had metastases in RxWBS). A sTg <1 ng/mL predicted statistically significant lower rates of recurrent/persistent disease and biochemical/structural incomplete responses. In conclusion, preablation sTg and DxWBS contribute to the detection of unknown or persistent metastatic disease in intermediate-risk DTC patients. A sTg <1 ng/mL in combination with a negative DxWBS is highly suggestive of the absence of remaining malignant disease, and one may consider deferring RAI ablation if both exams are negative. A stunning effect is rarely observed and it does not impair proper treatment of metastases.

Combination of Stimulated Thyroglobulin and Antithyroglobulin Antibody Predicts the Efficacy and Prognosis of 131I Therapy in Patients With Differentiated Thyroid Cancer Following Total Thyroidectomy: A Retrospective Study.

Background and PurposeThis study aimed to analyze the diagnostic ability of the combination of stimulated thyroglobulin (sTg) and antithyroglobulin antibody (TgAb) in predicting the efficacy and prognosis of radioactive iodine (131I) therapy (RAIT) in patients with differentiated thyroid carcinomas (DTCs) after total thyroidectomy (TT).MethodsThis retrospective study comprised 409 DTC patients who underwent 131I treatment following TT in the First Affiliated Hospital of Zhengzhou University from January 2019 to August 2020, and they were followed up to November 2021. Patients were divided into the successful ablation and the unsuccessful ablation group based on the classification of the efficacy of RAIT in the 2015 American Thyroid Association guidelines. The clinical characteristics and the efficacy of the initial RAIT were evaluated. The cutoffs of preablation sTg, sTg/thyroid-stimulating hormone (TSH) ratio, and sTg×TgAb product were calculated to predict the efficacy of RAIT. Univariate and multivariate logistic regression analyses were used to identify the independent risk factors for unsuccessful ablation. Kaplan–Meier curves were used to estimate the prognostic value of sTg×TgAb product affecting progression-free survival (PFS).ResultsThe cohort consisted of 222 cases in the successful ablation group and 187 cases in the unsuccessful ablation group. Between the two groups, preablation sTg, sTg/TSH ratio, and sTg×TgAb product were significantly higher in the unsuccessful ablation group. The area under the curve (AUC) of the sTg×TgAb product was the highest among the above three factors. The cutoffs for the worse therapeutic effect of the initial RAIT in sTg, sTg/TSH ratio, and sTg×TgAb were >2.99 ng/ml, >0.029 mg/IU, and >34.18, respectively. STg >2.99 ng/ml and sTg×TgAb product >34.18 were independent risk factors for unsuccessful ablation. Patients with sTg×TgAb product >34.18 had shorter PFS than that of patients with sTg×TgAb product ≤34.18. In separate analyses of TgAb-negative and TgAb-positive subgroups, higher sTg×TgAb was both associated with a lower success rate of RAIT and a shorter PFS.ConclusionSTg×TgAb product predicted the efficacy and prognosis of 131I therapy for both TgAb-negative and TgAb-positive DTC patients before the initial 131I treatment following TT. Thus, it can be used as a clinical reference indicator for the surveillance of DTC patients.

Age, thyroglobulin levels and ATA risk stratification predict 10-year survival rate of differentiated thyroid cancer patients.

IntroductionDifferentiated thyroid cancer (DTC) is the most common of endocrine cancers. Many studies have focused on recurrence-free survival of DTC patients, however, few studies have addressed overall survival rates. Given its very good prognosis, estimating overall or long-term survival in patients with DTC seems rational. So far, neither the impact of pre- and post-ablation thyroglobulin, nor that of initial American Thyroid Association (ATA) risk stratification on long-term disease-specific survival, have been sufficiently studied.ObjectiveThe aim of this study was to determine the factors that influence long-term disease-specific survival and thyroglobulin levels in patients with DTC who have been previously treated with thyroidectomy and radioactive iodine (RAI) remnant ablation.Patients and methodsThis observational retrospective study included 1093 patients who were treated for DTC between 1995 and 2010 and are still monitored in our tertiary center. Only patients who needed RAI ablation after thyroidectomy were included in this study. Patients who were treated with RAI following rhTSH stimulation, patients who presented positive anti-thyroglobulin antibodies, and patients who had micro-cancers were excluded. Pre-ablation stimulated thyroglobulin (Pre-ablation sTg) was measured after thyroid hormone withdrawal (THW), just before RAI.ResultsAccording to ATA standards, 29 patients (2.7%) were classified as high-risk patients. Initial ATA high-recurrence risk rating (HR 21.9; 95% CI: 8.5-56.3), age>55 years (HR 23.8; 95%-CI: 7.5-75.3) and pre-ablation sTg≥30 μg/l (HR 8.4; 95% CI: 4.6-15.3) significantly impacted ten-year survival. Moreover, age over 45 years, ATA moderate-risk and follicular DTC were also significant. Ten-year survival was lower in ATA high-risk patients (51% vs 95% and 93% for the low and intermediate risk; p<10-7), patients older than 55 years (82% vs 98%; p<10-7), and in patients with pre-ablation sTg≥30 (78% vs 95%; p<10-7). Three rates of long-term survival were distinguished: excellent (survival rate of 99% in patients<55 years with pre-ablation sTg <30μg/l) representing 59% of the cohort, moderate (survival rate of 94.5% in patients <55 years with pre-ablation sTg ≥30μg/l or ≥55 years with pre-ablation sTg <30 μg/l) representing 38% of the cohort, and low (survival rate of 49% in patients ≥55 years with pre-ablation sTg ≥30μg/l) representing 3% of the cohort.ConclusionInitial ATA high-risk classification, age over 55 years old and pre-ablation sTg ≥30 μg/l are the main negative factors that influence the ten-year survival in DTC. We suggest three categories of overall survival rates. Patients older than 55 years with pre-ablation sTg ≥30 μg/l have the worst survival rate.

The role of thymus preservation in parathyroid gland function and surgical completeness after bilateral central lymph node dissection for papillary thyroid cancer: A randomized controlled study

BackgroundThe clinical value of thymus preservation during thyroid carcinoma surgery remains unclear. The aim of this study is to explore the role of bilateral thymus preservation in parathyroid glands (PGs) function and surgical completeness in total thyroidectomy (TT) with bilateral central lymph node dissection (CLND). Materials and methodsFifty-four consecutive patients who underwent TT and bilateral CLND were assigned to the thymus preservation (TP) group (n = 27) and the bilateral thymectomy (BT) group (n = 27). Surgical completeness was evaluated by the number of lymph nodes dissected, serum Tg level and ultrasound findings postoperatively. ResultsIncidental parathyroidectomy was more common in the BT group (29.6% vs 7.4%, p = 0.038). Patients in the BT group had higher risks of neuromuscular symptoms (63.0% vs 29.6%, P = 0.014) and transient hypoparathyroidism (70.4% vs 25.9%, P = 0.001). The incidence of persistent hypoparathyroidism failed to show a significant difference between the TP and BT groups (0 vs 14.8%, P = 0.111). However, those with transient hypoparathyroidism in the BT group had a lower level of serum PTH at 3 weeks postoperatively (p = 0.001). There was no significant difference in the number of lymph nodes dissected (5.89 ± 3.12 vs 8.56 ± 6.93, P = 0.077) and preablation sTg level (1.82 ± 2.18 vs 1.42 ± 1.56 ng/ml, P = 0.775) between the TP and BT groups. No metastatic lymph nodes were found on sonography at 3 months postoperatively in both groups. Conclusion: Thymus preservation had benefits on protecting PGs and promoting rapid clinical resolution of hypoparathyroidism. It had no effects on oncologic completeness of TT with bilateral CLND.

Efficacy and Affecting Factors of 131I Thyroid Remnant Ablation After Surgical Treatment of Differentiated Thyroid Carcinoma

Purpose: Radioiodine (131I) thyroid remnant ablation is an important treatment of differentiated thyroid carcinoma (DTC) and various factors affecting its efficacy have been reported but not well defined. The aim of our study was to evaluate the efficacy and the affecting factors of 131I ablation after total or near-total thyroidectomy in a relative large DTC cohort.Methods: 261 DTC patients with negative thyroglobulin antibody received 100–200 mCi 131I for thyroid remnant ablation after total or near-total thyroidectomy between January 2012 and October 2015 in our hospital. The efficacy and affecting factors of 131I ablation therapy were retrospectively investigated.Results: The success rate of the first 131I thyroid remnant ablation was 65.90%. Univariate analysis demonstrated that larger tumor size, higher level of pre-ablation stimulated thyroglobulin (sTg), intermediate to high risk stratification for recurrence, and lymph node and distant metastases were associated with a lower success rate of the first 131I ablation (all p < 0.05). Multivariate logistic regression analysis showed that tumor size, pre-ablation sTg, and lymph node and distant metastases were independent factors affecting the efficacy of the first 131I ablation. Areas under receiver operating characteristic curves for sTg, sTg/TSH ratio, and tumor size to predict unsuccessful ablation were 0.831, 0.824, and 0.648, respectively. The threshold values were 4.595 ng/ml, 0.046 mg/IU, and 1.350 cm, respectively. The sensitivities were 95.51, 96.63, and 73.03% and the specificities were 64.54, 61.63, and 49.41%, respectively. The excellent response (ER) ratio of the successful group was significantly higher than that of the unsuccessful group.Conclusions: The efficacy of the first 131I thyroid remnant ablation after surgical treatment of DTC is well demonstrated, and tumor size, pre-ablation sTg, lymph node, and distant metastases are independent factors affecting its efficacy.

Clinical significance of tracing thyroglobulin in predicting metastasis of post-operative patients with differentiated thyroid carcinoma before its first pre-ablation with 131I

Objective To investigate the value of tracing thyroglobulin(Tg)in predicting metastasis of post-operative patients with differentiated thyroid carcinoma(DTC)before its first pre-ablation with 131I. Methods 106 cases with DTC, undergoing total thyroidectomy and lymphadenectomy, were assigned to 2 groups as M0 group(without metastasis)and M1 group(with metastasis). Clinical data including pre-ablation stimulated thyroglobulin(sTg)and pre-operative Tg were determined. sTg, pre-operative Tg, Tg variation(ΔTg), and Tg variation rate (ΔTg/pre-operative Tg)between 2 groups were compared. The ROC curve and the diagnostic critical point(DCP)were analyzed. Results sTg, Pre-operative Tg, Tg variation, and Tg variation rate were significantly higher than those of M0(all P<0.01). The corresponding areas under the ROC curve(AUC)to differentiate the two groups were 0.913, 0.702, 0.773, and 0.943, respectively. The best diagnostic value points(DCP)were 40.60 ng/ml and -72.5%. The sensitivity and specificity were 70.21%, 100.00%, and 89.36%, 88.13%, respectively. Conclusion The pre-ablation sTg seems to be a useful diagnostic marker for predicting metastasis before the first 131I ablation. The sTg value can be effectively corrected by the Tg variation rate, and the sensitivity and accuracy of sTg for metastasis in DTC patients can be improved, finally providing evidence for pre-ablative assessment as well as strategies of 131I therapy. (Chin J Endocrinol Metab, 2018, 34: 102-105) Key words: Differentiated thyroid carcinoma; Thyroglobulin; Radioiodine therapy; Iodine radioisotopes

Significance of micrometastases in the calculation of the lymph node ratio for papillary thyroid cancer.

PurposeThe lymph node ratio (LNR) is an important prognostic factor in papillary thyroid carcinoma (PTC), but micrometastases in cervical lymph nodes (LNs) are not of great clinical importance. In this study, we analyzed the accuracy of prediction of the prognosis depending on whether micrometastases were included in the number of metastatic LNs when calculating LNR.MethodsThe study included 353 PTC patients who underwent total thyroidectomy with neck LN dissection, and calculated LNR by 2 methods according to whether micrometastases were included in the number of metastatic LNs: Method 1 did not and method 2 did include. To compare the predictive values of LNR by the 2 methods, correlation coefficients and receiver operating characteristic (ROC) curves were analyzed.ResultsPositive correlations were found between LNR and preablation stimulated thyroglobulin (sTg) levels in both methods, but the correlation between method 1 LNR and preablation sTg level was significantly stronger than that for method 2 (Fisher z = 1.7, P = 0.045). The areas under these 2 independent ROC curves were analyzed; the prognostic efficacy of method 1 LNR was more accurate than that of method 2 LNR, and the difference was statistically significant (P = 0.0001).ConclusionRegional recurrence of PTC can be predicted more accurately by not including micrometastases in the number of metastatic LNs when calculating LNR.

Pre-ablation stimulated thyroglobulin is a better predictor of recurrence in pathological N1a papillary thyroid carcinoma than the lymph node ratio.

Papillary thyroid carcinomas (PTC) with lymph node metastases have a high recurrence rate. We analyzed the potential of lymph node ratio (LNR) and the level of pre-ablation stimulated thyroglobulin (sTg) as risk factors predicting recurrence in patients with pathological N1a PTC. This study involved 192 patients with pathologically confirmed PTC and central neck lymph node metastases who underwent total thyroidectomy with central lymph node dissection (CLND). The clinico-pathological characteristics, the pre-ablation sTg level and post-treatment recurrences were examined. Univariate and multivariate analyses were performed to identify factors associated with recurrence in these patients. During a median follow-up of 63months, 17 patients had loco-regional recurrences. Receiver operating characteristic curve analysis showed that the appropriate cut-off values for LNR and the pre-ablation sTg level was 0.48 and 9.3ng/mL, respectively.Patients with LNR values of ≥0.48 had a significantly worse disease-free survival (DFS) than those with LNR values of <0.48 (P=0.015), and patients with pre-ablation sTg level values of ≥9.3ng/mL had significantly worse DFS than those with pre-ablation sTg level values <9.3ng/mL (P<0.001). Relative to patients with LNR values of <0.48, those with LNR values of ≥0.48 had higher median pre-ablation sTg level values (0.55 vs. 4.20; P<0.001). The correlation covariant between the LNR value and the pre-ablation sTg level value was r=0.454 (P<0.001).Multivariate analysis showed that a LNR value of ≥0.48 (P=0.386) was not an independent risk factor for recurrence. To the contrary, a pre-ablation sTg level value of ≥9.3ng/mL (P<0.001) was an independent risk factor for recurrence. A high pre-ablation sTg level is a better predictor of recurrence in pathological N1a PTC than a high LNR value.Careful follow-up of patients with this risk factor is recommended.

Effect of Hashimoto thyroiditis on low-dose radioactive-iodine remnant ablation.

Radioactive-iodine remnant ablation is an integral part of the papillary thyroid carcinoma (PTC) treatment. Although a minimum dose is usually recommended, there is controversy as to whether the low-dose (1100 MBq) radioactive-iodine remnant ablation is adequate for selected patients. A retrospective cohort study was conducted on 691 patients. Patients with no remnant thyroid on the follow-up whole body scan and low stimulated thyroglobulin (sTg) level (<2.0 ng/mL) were deemed as successful treatment cases. Initial low-dose radioactive-iodine remnant ablation was successful in 431 patients (62.3%). Multivariate analysis demonstrated a negative correlation between successful radioactive-iodine remnant ablation and coexisting Hashimoto thyroiditis based on histopathology diagnosis (odds ratio [OR] = 3.23; p < .001) as well as elevated preablation sTg (OR = 1.24; p < .001). Our data suggest that coexisting Hashimoto thyroiditis and elevated sTg are negative predictive factors for successful low-dose radioactive-iodine remnant ablation treatment. An appropriate risk-adjusted approach may improve the efficacy of radioactive-iodine remnant ablation treatment. © 2015 Wiley Periodicals, Inc. Head Neck 38: E730-E735, 2016.

Relationship between Variation of Pre-ablation Stimulated Thyroglobulin and Distant Metastasis in Patients with Differentiated Thyroid Cancer.

To investigate the relationship between the dynamic variation of pre-ablation stimulated thyroglobulin(sTg)and distant metastasis in patietns with differentiated thyroid cancer(DTC). DTC patients after total or near total thyroidectomy were divided into two groups as M1 group(n=38)and M0 group(n=130)according to the presence of distant metastases or not. Clinical data including pre-ablation sTg and the corresponding thyrotropin(TSH)values were dynamically measured. The pre-ablation sTg and corresponding TSH collected at the first time were defined as Tg1 and TSH1,while as Tg2 and TSH2 at the last time. χ(2) test was used to compare the variation tendency of sTg between these two groups. Tg1,Tg2,pre-ablation sTg variation(∆Tg),and ∆Tg/∆TSH ratio between M0 and M1 were compared by Mann-Whitney rank-sum test. The receiver operating characteristic(ROC)curves and diagnostic critical point(DCP)were employed to evaluate the predictive values of the above indicators. Both Tg1 and Tg2 of M1 were significantly higher than those of M0(the Mann-Whitney rank-sum test:Tg1 P<0.001,Tg2 P<0.001). The corresponding areas under the ROC curve(AUC)to differentiate the two groups were 0.921 and 0.942,respectively. The cut-off value of Tg2,which was more accurate in predicting distant metastasis,was 24.3 ng/ml with a sensitivity of 92.11% and a specificity of 83.85%. Both ∆Tg and ∆Tg/∆TSH between these two groups were significantly different(the Mann-Whitney rank-sum test:∆Tg P=0.002,∆Tg/∆TSH P<0.001). ∆Tg/∆TSH worked better than Tg2 in predicting distant metastasis with both higher accuracy(87.50%)and higher specificity(86.92%). Dynamically tracing pre-ablation sTg may improve the accuracy and specificity of distant metastases prediction in DTC patients. ∆Tg/∆TSH,which means the ratio of sTg variation to TSH variation,may be a useful diagnostic marker for predicting distant metastases in DTC.

A systematic review and meta-analysis evaluating completeness and outcomes of robotic thyroidectomy.

Despite immense interest, robotic-assisted thyroidectomy (RT) remains controversial in differentiated thyroid carcinoma (DTC). This systematic review and meta-analysis compared surgical completeness and/or oncological outcomes between RT and open thyroidectomy (OT) in low-risk DTC. Systematic review. A systematic review was performed to identify studies that compared surgical completeness and/or oncological outcomes between RT and OT in DTC. Any study that compared at least one parameter relating to surgical completeness and/or oncological outcome for DTC was considered. Number of central lymph nodes (CLNs) retrieved during central neck dissection (CND), preablation stimulated thyroglobulin (sTg) level, radioiodine uptake on post-therapy scan, and locoregional recurrence (LRR) were examined. Meta-analysis was performed using a fixed or random-effects model depending on heterogeneity between studies. Ten studies were eligible. Of the 2,205 DTCs, 752 (34.1%) had RT, whereas 1,453 (65.9%) had OT. Relative to OT, RT had significantly fewer CLNs retrieved during CND (4.7 ± 3.2 vs. 5.5 ± 3.8, standardized mean difference [SMD] = -0.240, 95% confidence interval [CI]: -0.364 to -0.116, P < .001) and higher preablation sTg level (3.6 ± 6.7 ng/mL vs. 2.0 ± 5.0 ng/mL, SMD = 0.272, 95% CI: 0.022 to 0.522, P = .033). Interestingly, these differences were more evident in the robotic transaxillary approach (RTAA) than the robotic bilateral axillo-breast approach. After a mean follow-up of 17.7 months, no LRR was found in RT, whereas after 18.6 months, one LRR was found in OT. Relative to OT, total thyroidectomy by RTAA was associated with fewer CLNs retrieved and less-complete thyroid resection. However, using RTAA is unlikely to compromise the outcomes of low-risk DTC because of its inherently good prognosis.

Predictive factors and pattern of locoregional recurrence after prophylactic central neck dissection in papillary thyroid carcinoma.

Prophylactic central neck dissection (pCND) at the time of the total thyroidectomy (TT) remains controversial in clinically nodal-negative (cN0) papillary thyroid carcinoma. Our study was designed to examine the predictive factors and pattern of locoregional recurrence (LRR) after pCND in the context of the postoperative stimulated Tg (sTg) level. A total of 341 patients who underwent TT and unilateral pCND were analyzed. Patients with an identifiable lesion on ultrasonography or whole-body scan within 6 months of surgery were excluded. LRR was defined as an identifiable lesion on USG, which was later confirmed by cytology/histology. Preablation sTg level was taken 2 months after surgery, whereas postablation sTg level was taken 8 months after surgery. Cox regression was used in the univariate and multivariate analyses to identify significant independent factors for LRR. After a follow-up of 66.6 ± 38.6 months, 14 (4.1 %) suffered from LRR. The duration to first LRR was 36.4 ± 21.7 months. The estimated 5- and 10-year LRR rates were 5.1 and 6.1 %, respectively. Of these 14 LRR, 3 (21.4 %) involved the central compartment alone, 9 (64.3 %) involved the lateral compartment alone, and 2 (14.3 %) involved both central and lateral compartments. After adjusting for other clinicopathological factors, postablation sTg level ≥ 1 µg/L (hazard ratio 265.109, 95 % confidence interval 1.132-62075.644, p = 0.045) was the only independent predictor of LRR. Annualized risk of LRR after pCND was approximately 1 % in the first 5 years and 0.2 % in the subsequent 5 years. Most (78.6 %) LRRs involved the lateral compartment. Postablation sTg ≥ 1 µg/L significantly predicted risk of LRR.

Preablation Stimulated Thyroglobulin/TSH Ratio as a Predictor of Successful I(131)Remnant Ablation in Patients with Differentiated Thyroid Cancer following Total Thyroidectomy.

Background. About 90% of thyroid cancers are differentiated thyroid cancers. Standard treatment is total thyroidectomy followed by radioactive I131remnant ablation and TSH suppression with thyroxine. Unsuccessful ablation drastically affects the prognosis of patients with DTC particularly high risk individuals; therefore, identifying the factors that affect the success of ablation is important in the management of patients with DTC. sTg is a good predictor of successful ablation in DTC. Its levels can be influenced by tumor staging and TSH values, as well as other factors. Therefore, we did this study using TSH to correct the predictive value of sTg in success of RRA. Methods. We retrospectively reviewed the records of 75 patients with DTC, who underwent total thyroidectomy followed by RRA and TSH suppression. Results. Preablation sTg and sTg/TSH ratio are significantly associated with ablation outcome. Cutoff value for sTg to predict successful and unsuccessful ablation was 18 ng/mL with 76.7% sensitivity and 79.1% specificity, while for sTg/TSH cutoff was 0.35 with 81.4% sensitivity and 81.5% specificity (P < 0.001). Association was stronger for sTg/TSH ratio with adjusted odds ratio (AOR) 11.64 (2.43–55.61) than for sTg with AOR 5.42 (1.18–24.88). Conclusions. Preablation sTg/TSH ratio can be considered as better predictor of ablation outcome than sTg, tumor size, and capsular invasion.