Prognostic significance of successful ablation with radioiodine of differentiated thyroid cancer patients

Combined clinical variable and radiomics of post-treatment total body scan for prediction of successful I-131 ablation in low-risk papillary thyroid carcinoma patients

To explore the feasibility of combined radiomics of post-treatment I-131 total body scan (TBS) and clinical parameter to predict successful ablation in low-risk papillary thyroid carcinoma (PTC) patients. Data of low-risk PTC patients who underwent total/near total thyroidectomy and I-131 ablation 30 mCi between April 2015 and July 2021 were retrospectively reviewed. The clinical factors studied included age, sex, and pre-ablative serum thyroglobulin (Tg). Radiomic features were extracted via PyRadiomics, and radiomic feature selection was performed. The predictive performance for successful ablation of the clinical parameter, radiomic, and combined models (radiomics combined with clinical parameter) was calculated using the area under the receiver operating characteristic curve (AUC). One hundred and thirty patients were included. Successful ablation was achieved in 77 patients (59.2%). The mean pre-ablative Tg in the unsuccessful group (15.50 ± 18.04 ng/ml) was statistically significantly higher than those in the successful ablation group (7.12 ± 7.15 ng/ml). The clinical parameter, radiomic, and combined models produced AUCs of 0.66, 0.77, and 0.87 in the training sets, and 0.65, 0.69, and 0.78 in the validation sets, respectively. The combined model produced a significantly higher AUC than that of the clinical parameter (p < 0.05). Radiomic analysis of the post-treatment TBS combined with pre-ablative serum Tg showed a significant improvement in the predictive performance of successful ablation in low-risk PTC patients compared to the use of clinical parameter alone.Thai Clinical Trials Registry TCTR identification number is TCTR20230816004 ( https://www.thaiclinicaltrials.org/show/TCTR20230816004 ).

Long-term predictive value of highly sensitive thyroglobulin measurement

OBJECTIVE

To examine the predictive value of unremarkable nonstimulated highly sensitive thyroglobulin (hsTg) measurement with regard to the results of stimulated thyroglobulin (Tg) measurement, diagnostic whole-body scintigraphy, recurrence and differentiated thyroid cancer (DTC)-related death.

DESIGN, PATIENTS AND MEASUREMENTS

We retrospectively analysed the data of all 461 (410 without anti-Tg-antibodies [TgAbs], 51 with) DTC patients who were referred to our department for treatment and follow-up care of differentiated thyroid cancer from 2004 onwards, and in whom at least one posttreatment Tg value was measured in our hospital at least 3 months after I-131 ablation.

RESULTS

In the group of TgAb-negative patients, 2.0% of patients with an unstimulated Tg < 0.1 ng/ml showed a stimulated Tg ≥ 1.0 ng/ml, whereas this happened in 77.6% with an unstimulated Tg ≥ 0.1 but <1.0 ng/ml. An unstimulated hsTg ≥ 0.1 ng/ml had a sensitivity specificity positive and negative predictive value of 90.0%, 94.1%, 77.6% and 97.6%, respectively, for a stimulated Tg ≥ 1.0 ng/ml. In TgAb-positive patients, this was 75%, 97%, 75% and 97%, respectively. An unstimulated Tg ≥ 0.1 ng/ml did not significantly discriminate with regard to the risk of DTC-related death (p = .06), but ≥1.0 ng/ml did (p = .012), as did a stimulated Tg ≥ 1.0 ng/ml (p = .029). Excluding patients with distant metastases at diagnosis nullifies this significance.

CONCLUSION

Except for patients with distant metastases, both TgAb negative and TgAb positive patients with an undetectable nonstimulated hsTg measurement have a very good prognosis. The high net present value of unstimulated hsTg testing means that further diagnostic procedures can be omitted in such patients.

Preradioactive Iodine Thyroglobulin Levels as Predictors of Metastasis in Well-Differentiated Thyroid Carcinoma Patients

Objective The aim of this study was to determine the cut-off value of thyroglobulin (Tg) levels as a predictor of metastases in post total thyroidectomy patients with well-differentiated thyroid carcinoma (DTC).

Materials and Methods A retrospective case-control study with an observational diagnostic approach was done. Subjects were 102 DTC patients divided into a case group with metastases and a control group without metastases. Tg and antithyroglobulin antibody (ATA) levels on thyroid-stimulating hormone (TSH)-stimulated preradioactive iodine were compared with each other. Diagnosis of metastases was based on postradioactive iodine whole-body scan. The cut-off value for Tg preradioactive iodine and the area under the curve (AUC) were obtained from the receiver operating characteristic curve.

Result The characteristics and histopathological type of DTC among these two groups were not significantly different (p = 0.47). The Tg levels in the case and control groups were 106 (2.2–6,000) ng/mL and 2.7 (0.3–10.10) ng/mL, respectively (p = 0.0001). TSH level in the case group was 50 (30–107) µIU/mL and in the control was 50 (20–100) µIU/mL (p = 0.224). ATA levels in the case and control groups were 0–3,000 and 0–629 ng/mL, respectively (p = 0.01). The AUC was 0.976 with a 95% confidence interval of 0.924 to 0.996 and a standard error of 0.016. The cut-off value of preradioactive iodine Tg was 10.1 ng/mL or higher with sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 96.1, 100, 98.0, 100, and 96.2%, respectively.

Conclusion Preradioactive iodine Tg level 10.1 ng/mL or higher can be used as a predictor of metastasis in patients with DTC.

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 PURPOSE

This 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).

METHODS

This 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).

RESULTS

The 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.

CONCLUSION

STg×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.

Radioiodine in Differentiated Thyroid Carcinoma: Do We Need Diagnostic Pre-Ablation Iodine-123 Scintigraphy to Optimize Treatment?

Changing insights regarding radioiodine (I-131) administration in differentiated thyroid carcinoma (DTC) stir up discussions on the utility of pre-ablation diagnostic scintigraphy (DxWBS). Our retrospective study qualitatively and semi-quantitatively assessed posttherapy I-131 whole-body scintigraphy (TxWBS) data for thyroid remnant size and metastasis. Findings were associated with initial treatment success after nine months, as well as clinical, histopathological, and surgical parameters. Possible management changes were addressed. A thyroid remnant was reported in 89 of 97 (92%) patients, suspicion of lymph node metastasis in 26 (27%) and distant metastasis in 6 (6%). Surgery with oncological intent and surgery by two dedicated thyroid surgeons were independently associated with a smaller remnant. Surgery at a community hospital, aggressive tumor histopathology, histopathological lymph node metastasis (pN1) and suspicion of new lymph node metastasis on TxWBS were independently associated with an unsuccessful treatment. Thyroid remnant size was unrelated to treatment success. All 13 pN1 patients with suspected in situ lymph node metastases on TxWBS had an unsuccessful treatment, opposite 19/31 (61%) pN1 patients without (p = 0.009). Pre-ablative knowledge of these TxWBS findings had likely influenced management in 48 (50%) patients. Additional pre-ablative diagnostics could optimize patient-tailored I-131 administration. DxWBS should be considered, especially in patients with pN1 stage or suspected in situ lymph node metastasis. Dependent on local surgical expertise, DxWBS is not recommended to evaluate thyroid remnant size.

The Influences of TSH Stimulation Level, Stimulated Tg Level and Tg/TSH Ratio on the Therapeutic Effect of 131I Treatment in DTC Patients

PURPOSE

To study the influences of pre-ablation TSH stimulation level, sTg and sTg/TSH ratio on the therapeutic effect of the first ¹³¹I treatment in DTCs.

METHODS

According to the thyroid stimulating hormone (TSH) levels (mU/l), all the 479 differentiated thyroid cancer (DTC) patients were divided into two groups: TSH < 30 and TSH ≥ 30. The TSH ≥ 30 group was divided into three subgroups: 30 ≤ TSH < 60, 60 ≤ TSH < 90 and TSH ≥ 90. The clinical features and the therapeutic effects of the first ¹³¹I treatment were analyzed. The cutoffs of stimulated thyroglobulin (sTg) and sTg/TSH ratio were calculated to predict the therapeutic effect of ¹³¹I treatment.

RESULTS

Among the three subgroups, the TSH ≥ 90 subgroup was younger and less likely to be associated with cervical lymph node metastasis (LNM). The postoperative levothyroxine (L-T₄) dose in the 60 ≤ TSH < 90 subgroup was the lowest. Between the two groups, patients in the TSH < 30 group had higher postoperative L-T₄ dose and longer thyroid hormone withdrawal (THW) time. The excellent response rates six months after the first ¹³¹I treatment among the three subgroups and between the two groups were not of statistical significance. The distribution of different TSH stimulation levels among each response group was similar. The cutoffs for the better therapeutic effect of the first ¹³¹I treatment in sTg and sTg/TSH were < 9.51 ng/ml and < 0.11, respectively. Both univariate and multivariate logistic regressions showed that cervical LNM, distant metastasis, higher sTg and higher sTg/TSH ratio predicted poorer therapeutic effect.

CONCLUSIONS

There was no significant influence of TSH stimulation levels before the first ¹³¹I treatment on the therapeutic effect of DTC. The sTg/TSH ratio can be considered as another predictor of ¹³¹I therapeutic effect.

Advantages of dosimetry in 131I therapy of differentiated thyroid carcinoma

For advanced differentiated thyroid carcinoma (DTC) several iodine-131 (131I) activity selection strategies are available. The most common approach empirical activity selection, in which the physician chooses an activity based on convention, experience and patient related parameters. The second available strategy is to perform lesion dosimetry. In this case, the activity to be administered is determined after a pretherapeutic dosimetric assessment to calculate the minimal activity required to achieve an effective absorbed dose or a maximum safe activity based on the delivered blood/bone marrow absorbed dose of 2 Gy as determined by blood and whole-body measurements. In contrast to the situation for lesion-based dosimetry, for the maximum safe activity-based approach several studies on outcome are available. In the present paper, an argument for the use of dosimetry in advanced DTC will be presented.

European Perspective on 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: Proceedings of an Interactive International Symposium

BACKGROUND

The American Thyroid Association (ATA) management guidelines for patients with thyroid nodules and differentiated thyroid cancer (DTC) are highly influential practice recommendations. The latest revision appeared in 2015 ("ATA 2015"). These guidelines were developed predominantly by North American experts. European experts frequently have different perspectives, given epidemiological, technological/methodological, practice organization, and medicolegal differences between the respective regions.

SUMMARY

Divergent viewpoints were the focus of an invited symposium organized by the European Association of Nuclear Medicine involving 17 European thyroidologists, four ATA Guidelines Taskforce members, and an audience of 200 international experts. The group discussed the preoperative assessment of thyroid nodules, surgery and the role of pathology, radioiodine (RAI) therapy (RAIT), the assessment of initial therapy and dynamic risk stratification, and the treatment of persistent disease, recurrences, and advanced thyroid cancer. The dialogue resulted in this position paper contrasting European and ATA 2015 perspectives on key issues. One difference pertains to the permissiveness of ATA 2015 regarding lobectomy for primary tumors ≤4 cm. European panelists cited preclusion of RAIT, potential need for completion thyroidectomy, frequent inability to avoid chronic thyroid hormone replacement, and limitations of supportive evidence as arguments against widely applying lobectomy. Significant divergence involved ATA 2015's guidance regarding RAIT. European panelists favored wider use of postoperative RAIT than does ATA 2015. Rationales included the modality's association with favorable patient outcomes and generally limited toxicity, and lack of high-quality evidence supporting withholding RAIT. Additionally, European panelists favored recombinant human thyrotropin (rhTSH) in more settings than does ATA 2015, citing avoidance of hypothyroid morbidity and quality-of-life impairment, without apparent sacrifice in oncologic outcomes. Based on clinical evidence plus theoretical advantages, European experts advocated dosimetric versus fixed-activity RAIT approaches for advanced DTC. European panelists noted that the ATA 2015 risk-stratification system requires information sometimes unavailable in everyday practice. ATA 2015 recommendations regarding RAI-refractory DTC should consider potential palliative benefits of RAIT in patients who also have RAI-susceptible lesions.

CONCLUSIONS

European panelists suggested modifications to approximately one-third of ATA 2015 recommendations. Varying European and ATA 2015 perspectives can stimulate analysis and discussion of the literature and performance of primary research to resolve discrepant recommendations and potentially improve patient outcomes.

Effectiveness of Reduced Radioiodine Activity for Thyroid Remnant Ablation after Total Thyroidectomy in Patients with Low to Intermediate Risk Differentiated Thyroid Carcinoma

Aim: To compare the success rates of radioiodine therapy (RIT) for thyroid remnant ablation (TRA) after the administration of a high-standard activity (3700 MBq; 100 mCi) to a lower-activity regimen of 2000 MBq (54 mCi) I-131 in a cohort of differentiated thyroid carcinoma (DTC) patients (papillary, follicular, mixed, pT1a(m) – pT3, N0 – NX, R0). Methods: 135 patients received approx. 2000 MBq I-131 (54 mCi) for thyroid remnant ablation after total thyroidectomy for DTC, 137 patients received approx. 3700 MBq (100 mCi) I-131. Ablation success was defined as thyroglobulin (TG) levels < 0.5 ng/ml after stimulation, negative I-131 whole-body scan and inconspicuous results on neck ultrasonography approximately 6 months after initial RIT. Results: In the follow-up 84.4 % of patients in the reduced-activity group and 87.6 % of the patients in the standard-activity group did not show any relevant residual I-131 uptake in the thyroid bed (p = 0.454). 90 % in the reduced-activity group and 91 % in the standard-activity group demonstrated a stimulated TG level < 0.5 ng/ml (p = 0.969). All patients were unre-markable in cervical ultrasonography. The success rate was comparable in both groups (81.5 % in the reduced-activity group vs. 83.9 % in the standard-activity group, p = 0.592). No re-therapy was required in 85.2 % of the patients in the low-activity group as compared to 87.6 % of the patients in the standard-activity group (p = 0.563). Conclusions: We could demonstrate that irrespective of the activity administered, the patients had comparable success rates with regard to TRA as defined by our criteria. We thus consider the use of a reduced-activity regimen for TRA safe and feasible in the patient cohort examined in this study.

Timing of post 131I ablation diagnostic whole body scan in differentiated thyroid cancer patients

Ziel: Beantwortung der Frage, ob drei Monate nach 131I-Ablation als zu früh für eine diagnostische Radioiod-Ganzkörperszintigraphie (dxWBS) bei Patienten mit einem differenzierten Schilddrüsenkarzinom (DTC) anzusehen sind. Patienten, Material, Methode: Daten von 462 DTC-Patienten, die in unserem Klinikum behandelt worden waren, wurden analysiert. Alle Patienten wurden thyreoid ektomiert. Von 129 Patienten waren folgende Daten verfügbar a) eine dxWBS mit gleichzeitiger TSH-stimulierter Thyreoglobulin-Messung, die innerhalb von vier Monaten (max. 120 Tage) nach 131I-Ablation durchgeführt wurde ohne weitere therapeutische Maßnahmen zwischen Ablation und dxWBS, b) eine zweite dxWBS oder 131I-Therapie (rxWBS), die innerhalb von 1,5 Jahren nach Ablation durchgeführt wurde. Ergebnisse: Bei 25/129 Patienten stimmten die Ergebnisse der initialen und weiteren Scans nicht überein: Bei 15 von 54 Patienten (27%) mit einem positiven initialen dxWBS widersprachen diese Ergebnisse dem zweiten dxWBS oder rxWBS. Neue Läsionen wurden bei 10/74 (14%) Patienten mit einem initial negativen dxWBS entdeckt. Eine Diskordanz zwischen dem ersten und weiteren in der Nachsorge gemessenen stimulierten Tg-Werten wurde in 5/129 (4%) der Patienten gefunden: Bei 2/90 (2%) Patienten mit einer negativen ersten stimulierten Tg-Bestimmung wurde nachfolgend ein positives Ergebnis gefunden. Bei 3/29 (10%) Patienten mit einer positiven ersten Bestimmung wurde bei der zweiten Untersuchung ein negatives Ergebnis festgestellt. Schlussfolgerung: Weniger als vier Monate nach 131I-Ablation ist zu früh für eine diagnostische Radioiod-Ganzkörperszintigraphie mit zeitgleich TSH-stimulierter Tg-Messung. Die Ermittlung des richtigen späteren Zeitpunkts erfordert weitere Untersuchungen.

Das Zeitintervall zwischen 131I Ablation und diagnostischer Ganzkörperszintigraphie bei Patienten mit differenziertem Schilddrüsenkarzinom Weniger als vier Monate nach Ablation dürfte zu früh sein

Radioiodine for High Risk and Radioiodine Refractory Thyroid Cancer: Current Concepts in Management

The management of early stage differentiated thyroid cancer (DTC) with low risk of recurrence has been the subject of much interest and investigation in the recent years. Locally advanced DTC and patients with a high risk of recurrent disease however needs further investigation. This short review will look at what constitutes high risk thyroid cancer, the definition of radioiodine refractory disease, the current management and areas of debate within this clinical setting.

In Patients With Low- to Intermediate-Risk Thyroid Cancer, a Preablative Thyrotropin Level of 30 μIU/mL Is Not Adequate to Achieve Better Response to 131I Therapy

PURPOSE

The optimal preablative level of thyrotropin (TSH) for patients with differentiated thyroid cancer (DTC) to achieve better response after I ablation remains unknown. The objective of this study was to assess whether a higher preablative TSH level above 30 μIU/mL is associated with better response to I therapy in low- to intermediate-risk DTC and to explore the potential factors that may impact their responses.

PATIENTS AND METHODS

A total of 204 consecutive non-high-risk patients were retrospectively reviewed. Serum TSH and thyroglobulin (Tg) levels were measured right before I treatment after thyroxine hormone withdrawal (THW). Patients were categorized by their preablative TSH level grouping of 30 to less than 60 (n = 11), 60 to less than 90 (n = 61), 90 to less than 120 (n = 56), 120 to less than 150 (n = 33), and 150 μIU/mL or greater (n = 43). Responses to I therapy were evaluated as excellent, indeterminate, biochemical incomplete, or structural incomplete response (ER, IDR, BIR, or SIR) after a mean follow-up of 20.3 months. Initial risk factors (age, sex, T and N status by AJCC/UICC TNM staging system, and thyroid remnant), the administered dose of I and response to I therapy were compared among different preablative TSH groups. Multivariate analysis was further performed to identify factors associated with incomplete response (IR, including BIR and SIR).

RESULTS

Except the significant correlation between younger age and higher preablative TSH level (P = 0.001), the 5 TSH groups did not differ in other related prognostic factors or dose of I (all P > 0.05). Among each ascending TSH group, ER was observed in 54.5%, 68.9%, 73.2%, 69.7%, and 60.5%, respectively, whereas IR was observed in 18.2%, 18.0%, 7.1%, 9.1%, and 20.9%, respectively. Group 90 to less than 120 μIU/mL presented the highest rate of ER and lowest rate of IR. In the multivariate analysis, preablative TSH level, in addition to preablative Tg, was also an associated factor for response to I therapy (P = 0.048).

CONCLUSIONS

A preablative TSH level of 90 to less than 120 μIU/mL might be more appropriate for patients with low- to intermediate-risk DTC to achieve better response to I therapy.

Antithyroglobulin Antibody as a Marker of Successful Ablation Therapy in Differentiated Thyroid Cancer

The aim of this study was to determine the role of antithyroglobulin antibody (ATA) serum as a marker of successful I-131 ablation therapy in differentiated thyroid cancer (DTC) patients with low serum thyroglobulin (Tg). A retrospective study was conducted on 60 patients (10 males and 50 females). All patients underwent posttotal thyroidectomy and received 2.96 to 3 GBq I-131 ablation. Subjects were divided into two groups with succesful and unsuccessful I-131 ablation therapies. The data of age, gender, histopathologic type, tumor size, and metastasis were collected. Preablation serum Tg and ATA level (Tg1 and ATA1) 6–12 months after ablation (Tg2 and ATA2) were measured. The success of ablation therapy was evaluated by diagnostic whole body scan (DxWBS) 6–12 months after ablation. There were no significant differences in age, gender, type of histopathology, tumor size, and nodal metastasis between the two groups. ATA2 ≤30 kIU/L were found in 23 (62.2%) subjects with successful ablation therapy, and ATA2 >30 kIU/L in 16 (69.6%) subjects belonged to the unsuccessful group (P = 0.017). Changes between ATA1 and ATA2 levels did not differ significantly in both the groups (P = 0.062). Tg1 <10 mg/L was found in 26 (57.8%) subjects with successful therapy (P = 0.037). Multivariate analysis showed ATA2 and Tg1 as the independent factors for the success of ablation therapy (P = 0.007 and 0.015). Adjusted odds ratio of postablation ATA was 5.379 [95% confidence interval (CI) 1.590 to 18.203] and preablation Tg was 5.822 (95% CI 1.418 to 23.902). ATA levels at 6–12 months after ablation, by considering the preablation Tg levels, is a useful marker to determine successful ablation therapy in WDTC patients with low serum Tg. Changes in serum ATA levels, although not statistically significant, can provide additional information about the course of the disease.

Patients with high-risk differentiated thyroid cancer have a lower I-131 ablation success rate than low-risk ones in spite of a high ablation activity

OBJECTIVE

To examine success rates in strictly defined high-risk differentiated thyroid cancer (DTC) patients who received a high-activity (≥5550 MBq) adjuvant postoperative I-131 therapy and compare these to the rates found in highest risk and low-risk patients.

DESIGN

Retrospective database study.

PATIENTS

We examined 377 patients with DTC who received I-131 ablation. Patients with distant metastases were classified as very high risk. Patients with primary tumours >4 cm, extensive extrathyroidal invasion (pT4a or pT4b in accordance with the 7th edition of the TNM system), and patients with ≥5 lymph node metastases or any lateral compartment lymph node metastases were considered high risk. All other patients were considered low risk.

MEASUREMENTS

Ablation success rate at first TSH-stimulated follow-up.

RESULTS

The ablation success rate was 72·6% in low-risk patients, 51·7% in high-risk patients and 13·8% in highest risk patients (all differences P < 0·001). In none of the groups, a significant difference in the initial I-131 activity was found between patients with successful and unsuccessful ablation (low risk: P = 0·16, high risk: P = 0·91 and highest risk: P = 0·48). Furthermore, there was no difference in ablation success between patients who received <5550 MBq and those who received ≥5550 Mbq (low risk: P = 0·31, high risk: P = 0·69 and highest risk: P = 0·22).

CONCLUSIONS

Patients with high-risk DTC have a significantly reduced I-131 ablation success rate compared to low-risk ones in spite of high initial I-131 activities. As successful ablation is prognostically important, efforts should be made to improve outcome in these patients.

Tc-99m imaging in thyroidectomized differentiated thyroid cancer patients immediately before I-131 treatment

PURPOSE

The aim of this study was to evaluate the clinical role of technetium-99m pertechnetate (Tc-99m) imaging in thyroidectomized differentiated thyroid cancer patients immediately before radioiodine-131 (I-131) treatment (Tx).

PATIENT AND METHODS

Eighty-six consecutive post-total-thyroidectomy patients (15 men, 71 women; mean age: 46.8 years) with pathologically diagnosed differentiated thyroid cancer were retrospectively studied. Tc-99m imaging immediately before I-131 Tx using both patient-based and lesion-based measurements were analyzed and were further compared with those of post-Tx I-131 whole-body scans.

RESULTS

For patients with unequivocally positive Tc-99m uptake, the sensitivity was 77% (patient-based) and 59% (site-based). The positive predictive value (PPV) was 100% for both patient-based and site-based measurements. If equivocal Tc-99m uptake was counted as positive, the sensitivity was 83 and 67%, and the PPV was 100 and 99% for patient-based and site-based measurements, respectively.

CONCLUSION

(a) To increase sensitivity yet maintaining high PPV, equivocal Tc-99m uptake should be considered a positive finding. (b) The nearly 100% PPV of Tc-99m imaging immediately before I-131 Tx for remnant detection suggests that Tc-99m imaging not only serves as an alternative to low-dose I-131 scanning in the low-risk post-thyroidectomy patients but also provides a clue for the subsequent I-131 therapeutic dosage and even for the outcome prediction.

Implication of different clinical and pathological variables in patients with differentiated thyroid cancer on successful ablation for 3700 MBq (131)I: a single Egyptian institutional experience over 14 years

OBJECTIVE

Is to investigate possible factors predicting success of ablation for 3700 MBq radioactive iodine 131 in patients with differentiated thyroid cancer (DTC) following near total thyroidectomy.

METHODS

This retrospective study enrolled 272 patients between 2000 and 2014. The success or failure of ablation was assessed 6 months after given the dose and our criteria for complete successful remnant ablation defined as: Negative (131)I whole body scan with no residual functioning thyroid tissue or distant functioning metastases and stimulated thyroglobulin (Tg) level less than 2 ng/ml. Different clinical and pathological factors, such as age, gender, tumor histology, grade and variants, size of primary malignant lesion, stage, and risk assessment according to the American (ATA) and European Thyroid Association (ETA) guidelines, associated pathology, tumor mutifocality, lymph node (LN) metastases and their number, invasiveness of the tumor (capsular invasion of the nodule, extra-thyroidal extension, and vascular invasion), baseline stimulated Tg level, and pre-ablative diagnostic scan were assessed.

RESULTS

There were 185 successful ablations (68 %). The baseline-stimulated Tg measured before the ablation was the only independent predictor of ablation success in multivariate analysis (P < 0.0001) with odds ratio (OR) of 2.64 (95 % CI: 1.54-4.54) and the optimal cutoff for this was 3.8 ng/mL. On the univariate analysis, LN metastases was predictor of ablation failure (P value = 0.03).

CONCLUSION

Baseline-stimulated Tg level is clinically important and had a significant predictive value for successful ablation; therefore, higher pre-ablation Tg should potentially be incorporated in the decision making for (131)I dosage or other treatment. In accordance with other studies, this is also applicable to cervical lymph nodal involvement and thyroid capsule invasion.

Different Radioiodine Dose for Remnant Thyroid Ablation in Patients With Differentiated Thyroid Cancer: A Meta-analysis

OBJECTIVE

Remnant thyroid ablation is crucial in the management of patients with differentiated thyroid cancer. However, the optimal dose of radioactive I for ablation is still controversial. This study aimed to compare the success rate of different activities of I for postoperative remnant ablation in randomized controlled trials (RCTs) and to determine the optimal dose.

PATIENTS AND METHODS

Sources were retrieved from the Cochrane Library, Medline, Embase, Scopus, and Google Scholar until March 2014. All RCTs that assessed the efficacy of different doses of I for ablation were selected. After data extraction, statistics were performed by Review Manager 5.2 software.

RESULTS

Seventeen RCTs were considered eligible, involving 3737 patients. The overall methodological quality of the studies was good. The rate of successful remnant ablation of low versus moderate I activities (risk ratio [RR], 0.89; 95% confidence interval [CI], 0.80-1.00; P = 0.06) and moderate versus high I activities (RR, 0.94; 95% CI, 0.89-1.00; P = 0.05) showed no significant differences. However, high I activities had 11% higher successful ablation rate than low activities with an RR of 0.89 (95% CI, 0.81-0.97; P = 0.008), which was significant.

CONCLUSIONS

We summarized all available randomized evidence to demonstrate that high dose of I was significantly better than low dose to achieve successful remnant thyroid ablation.

Risk factors for persistent disease in papillary thyroid carcinoma with lymph node metastasis

PURPOSE

It is known that the presence of neck lymph node (LN) metastasis is correlated with persistent disease in papillary thyroid carcinoma (PTC) patients. After appropriate therapy, most patients become disease free, whereas some may still have persistent disease. The present study aimed to determine the potential variables affecting the clinical course of the disease and persistent disease patterns in PTC patients with LN metastasis.

MATERIALS AND METHODS

The study group included consecutive PTC patients with LN metastasis. Clinicopathological characteristics and persistent disease pattern during the follow-up period were examined to identify risk factors for persistent disease using univariate and multivariate analyses.

RESULTS

At the end of a median follow-up of 84 months, 90 (69%) patients became disease free and 40 (31%) patients had persistent disease. Univariate analysis showed that male sex, older age at initial diagnose (≥45 years), larger tumor size (>4 cm), presence of lateral cervical LN metastasis, extrathyroidal invasion, and higher number of metastatic LN (≥10) were significant predictors for persistent disease. Multivariate analysis showed that extrathyroidal involvement, presence of lateral cervical LN metastasis, and older age at initial diagnosis (≥45 years) were independent predictors for persistent disease.

CONCLUSION

Despite the presence of LN involvement, most patients may become disease free with therapy. Patients with extrathyroidal invasion, lateral cervical LN involvement, and those at least 45 years old at initial diagnosis are more likely to have persistent disease. However, disease control can be achieved with close clinical follow-up and therapy.

Intermediate-risk differentiated thyroid carcinoma patients who were surgically ablated do not need adjuvant radioiodine therapy: long-term outcome study

OBJECTIVE

The mute question is whether patients with DTC of intermediate risk of recurrence, second most common presentation, who were surgically ablated in the first place, ever needed adjuvant RAI therapy? This study exclusively evaluated the long-term outcome in intermediate-risk patients with DTC.

DESIGN

Two-arm retrospective cohort study conducted between years 1991 and 2012.

SETTING

Institutional practice.

PATIENTS

Intermediate-risk DTC patients, with pathologically proven T1/2 N1 M0, T3 with/without N1 M0 disease, with a minimum follow-up of 12 months, were included. Of 254 patients who fulfilled the inclusion/exclusion criteria, 125 patients were surgically ablated (Gr-I) and 129 patients had significant remnant and/nodal disease (Gr-II). No radioiodine in Gr-I and adjuvant RAI therapy was administered in Gr-II patients.

MEASUREMENTS

Baseline characteristics were compared and overall survival, event-free survival, disease-free survival/overall remission rates and recurrence rates were calculated for both the groups.

RESULTS

All baseline patient characteristics were comparable except 24-h RAIU between two groups. Depending on adjuvant radioiodine therapy outcome, Gr-II patients were subclassified as Gr-IIa (ablated) and Gr-IIb (not ablated). With a median follow-up duration of 10·3 years (range: 1-21 years), 12/125 (9·6%) patients had disease recurrence and 10 (8%) showed persistent disease in Gr-I. In Gr-IIa, 6/102 (5·9%) patients recurred but only one of them was successfully ablated with (131) I, and 5 (4·9%) had persistent disease. However, in Gr-IIb, 27 patients who failed first-dose adjuvant RAI therapy, 8/27 (29·6%) showed persistent disease (P = 0·000). Overall survival was 100%; however, disease-free survival rates were 92% and 90%, in Gr-I and Gr-II, respectively.

CONCLUSION

Intermediate-risk surgically ablated patients do not need adjuvant RAI therapy and patients who failed to achieve ablation with first dose of (131) I may be dynamically risk stratified as high-risk category and managed aggressively.

Factors affecting disease-free status of differentiated thyroid carcinoma patients

PURPOSE

The study aim was to assess factors that impact on the outcome of radioiodine therapy in patients diagnosed with differentiated thyroid carcinoma (DTC).

MATERIALS AND METHODS

We performed a retrospective cohort study on 256 patients with DTC who underwent thyroidectomy and received radioiodine therapy during December 2003 to January 2012. All patients were followed up for at least 1 year. They were considered disease- free by the criteria of the revised American Thyroid Association Management Guideline for Patients with Thyroid nodules and DTC (ATA guideline 2009).

RESULTS

On Cox univariate analysis, factors associated with disease-free status were age<45, stage I tumor, low risk group by histopathology, unifocal tumor involvement, stimulated serum Tg level at 1st dose of radioiodine therapy and no distant metastasis from 1st post-treatment WBS (post RxWBS). On multivariate analysis, stage I tumor and stimulated serum Tg level at 1st dose of radioiodine therapy<30 ng/mL were the significant prognostic factors that increased disease-free rate by 1.73 times and 2.60 times, respectively (P-value<0.05).

CONCLUSIONS

Factors affecting the outcome of radioiodine therapy in our study were age, stage, risk of recurrence by histopathology, unifocal tumor involvement and 1st postRxWBS findings. From these factors, stage I tumor and stimulated serum Tg level at 1st dose of radioiodine therapy were independent prognostic factors that substantial increase the disease-free rate.

Correlation of Consecutive Serum Thyroglobulin Levels During Hormone Withdrawal and Failure of Initial Radioiodine Ablation in Thyroid Cancer Patients

OBJECTIVE

The aim of this study was to evaluate the value of thyroglobulin (Tg) kinetics during preparation of radioiodine ablation for prediction of initial radioiodine ablation failure in thyroid cancer patients.

METHODS

Thyroid cancer patients after total thyroidectomy who underwent radioiodine ablation with 3-4 weeks of hormone withdrawal between May 2011 and January 2012 were included. Consecutive serum Tg levels 5-10 days before ablation (Tg1) and on the day of ablation (Tg2) were obtained. The difference between Tg1 and Tg2 (ΔTg), daily change rate of Tg (ΔTg/day) and Tg doubling time (Tg-DT) were calculated. Success of initial ablation was determined by the results of the follow-up ultrasonography, diagnostic radioiodine scan and stimulated Tg level after 6 to 20 months.

RESULTS

A total of 143 patients were included. Failed ablation was reported in 52 patients. Tg2 higher than 5.6 ng/ml and Tg-DT shorter than 4.2 days were significantly related to a high risk of ablation failure. ΔTg and ΔTg/day did not show significant correlation with ablation failure.

CONCLUSIONS

Thyroglobulin kinetics on consecutive blood sampling during hormone withdrawal may be helpful in predicting patients with higher risk of treatment failure of initial radioiodine ablation therapy in thyroid cancer patients.

Prediction of the success of thyroid remnant ablation using preablative 99mTc pertechnetate scintigraphy and postablative dual 131I scintigraphy

OBJECTIVE

The aim of this study was to predict the success of 131I ablation using preablative 99mTc pertechnetate salivary scintigraphy and a postablative dual 131I scan in differentiated thyroid cancer (DTC).

PATIENTS AND METHODS

A total of 168 DTC patients who underwent 131I ablation with preablative salivary scintigraphy and a postablative dual (early and delayed) 131I scan were enrolled. For salivary scintigraphy, the thyroid remnant uptake was visually assessed. For the dual 131I scan, the thyroid remnant to background uptake ratios (TBRs) on early and delayed scans were measured and the percentage change in TBR (TBRΔ) was calculated.

RESULTS

Thyroid remnant uptake was seen in 69 (41%) patients on salivary scintigraphy and in 162 (96%) patients on the dual 131I scan. The success rate of ablation was higher in patients with negative remnant uptake on salivary scintigraphy (86%) than in patients with positive remnant uptake (58%, P=0.0001). The success rate of ablation was 100% in patients with no remnant uptake on both salivary scintigraphy and the dual 131I scan. The success rate of ablation was higher in patients with TBRΔ 0 or more than in patients with TBRΔ less than 0, irrespective of remnant uptake on salivary scintigraphy (91 vs. 70%, P=0.03, for patients without remnant uptake on salivary scintigraphy; 74 vs. 48%, P=0.05, for patients with remnant uptake on salivary scintigraphy).

CONCLUSION

The success of thyroid remnant ablation in DTC can be predicted by the presence of remnant uptake on preablative 99mTc pertechnetate scintigraphy and change in remnant uptake on the postablative dual 131I scan.

Radioiodine remnant ablation in low-risk differentiated thyroid cancer patients who had R0 dissection is an over treatment

Low-risk (LR) differentiated thyroid cancer (DTC) patients should be ablated or not, albeit, with small dose of radioiodine is highly controversial. We hypothesized that those LR DTC patients who were surgically ablated need no radioiodine remnant ablation (RRA). This study aims to evaluate the long-term outcome in these two groups of patients. Retrospective cohort study conducted from January 1991 to December 2012. Based on extent of surgical resection and histopathology, LR DTC patients were classified as Gr-1: 169 patients, who were surgically ablated; Gr-2: 153 patients, who had significant remnant in thyroid bed. Basal parameters were comparable between two groups except pretherapy 24 h radioiodine uptake (0.16 ± 0.01% vs. 5.64 ± 0.46%; P < 0.001). No patient received RRA in Gr-1; Gr-2 patients were administered 30 mCi (131) I. Total number of events (recurrence, persistent, and progression of disease), with median follow up of 10.3 years, was observed in 10/322 (3.1%) of LR DTC patients. Only one patient had disease recurrence from Gr-1, who became disease-free after radioiodine therapy. Similarly, one patient from 126, who was ablated with single dose of RRA, had recurrence from Gr-2. However, 8/27 (29.7%) patients from Gr-2 had persistent disease; even two of them subsequently developed disease progression, who failed first-dose of RRA. The event-free survival rates were 99.4% and 94.1% (P = 0.006) in Gr-1 and Gr-2, respectively. RRA is an overtreatment in surgically ablated LR DTC patients. Successfully ablated RRA patients also had similar long-term outcome, however, those who failed, should be re-stratified as intermediate-risk category, and managed aggressively.

Determinants of successful ablation and complete remission after total thyroidectomy and ¹³¹I therapy of paediatric differentiated thyroid cancer

PURPOSE

In adult differentiated thyroid cancer (DTC) patients, successful ablation and the number of (131)I therapies needed carry a prognostic significance. The goal was to assess the prognosis of DTC in children and adolescents treated in our centre in relation to the number of treatments needed and to establish the determinants of both complete remission (CR) and successful ablation.

METHODS

Seventy-six DTC patients <21 years of age at diagnosis were included. Recurrence and death rates, rates of CR (=negative stimulated thyroglobulin, negative neck ultrasound and negative (131)I whole-body scintigraphy) and successful ablation (=CR after initial (131)I therapy) were studied.

RESULTS

No patients died of DTC. Seven patients were treated by surgery alone and did not show signs of recurrence during follow-up. Of the 69 patients also treated with (131)I therapy, 47 patients achieved CR, 25 of whom had successful ablation. In multivariate analysis, female gender and the absence of distant metastases were independent determinants of a higher CR rate. Female gender, lower T stage and higher (131)I activity (successful ablation, median activity 3.1 GBq, unsuccessful ablation 2.6 GBq) were determinants of a higher rate of successful ablation. After (131)I therapy no patient showed recurrence after reaching CR or disease progression if CR was not reached.

CONCLUSION

In our paediatric DTC population prognosis is extremely good with no deaths or recurrences occurring regardless of the number of (131)I therapies needed or whether CR was reached. The determinants of CR and successful ablation can be used to optimize the chance of therapy success.

Codon-optimized human sodium iodide symporter (opt-hNIS) as a sensitive reporter and efficient therapeutic gene

To generate a more efficient in vivo reporter and therapeutic gene, we optimized the coding sequence of the human sodium/iodide symporter (NIS) gene by replacing NIS DNA codons from wild type to new codons having the highest usage in human gene translation. The Codon Adaptation Index (CAI), representing the number of codons effective for human expression, was much improved (0.79 for hNIS, 0.97 for opt-hNIS). Both wild-type (hNIS) and optimized human NIS (opt-hNIS) were cloned into pcDNA3.1 and pMSCV vectors for transfection. Various cancer cell lines such as thyroid (TPC-1, FRO, B-CPAP), breast (MDA-MB-231), liver (Hep3B), cervical (HeLa), and glioma (U87MG) were transfected with pcDNA3.1/hNIS or pcDNA3.1/opt-hNIS. ¹²⁵I uptake by opt-hNIS-expressing cells was 1.6 ~ 2.1 times higher than uptake by wild-type hNIS-expressing cells. Stable cell lines were also established by retroviral transduction using pMSCV/hNIS or pMSCV/opt-hNIS, revealing higher NIS protein levels and ¹²⁵I uptake in opt-hNIS-expressing cells than in hNIS-expressing cells. Moreover, scintigraphic images from cell plates and mouse xenografts showed stronger signals from opt-hNIS-expressing cells than hNIS-expressing cells, and radioactivity uptake by opt-hNIS-expressing tumors was 2.3-fold greater than that by hNIS-expressing tumors. To test the efficacy of radioiodine therapy, mouse xenograft models were established with cancer cells expressing hNIS or opt-hNIS. ¹³¹I treatment reduced tumor sizes of hNIS- and opt-hNIS-expressing tumors to 0.57- and 0.27- fold, respectively, compared to their sizes before therapy, suggesting an improved therapeutic effect of opt-hNIS. In summary, this study shows that codon optimization strongly increases hNIS protein levels and radioiodine uptake, thus supporting opt-hNIS as a more sensitive reporter and efficient therapeutic gene.

Comparison between low and high radioactive iodine (131I) reablation dose in patients with papillary thyroid cancer

AIM

The aim of this study was to assess ablation outcome after a second ablation dose and compare the ablation rate after low and high reablation doses of iodine-131 ((131)I) after failure of the first ablation with 3700 MBq.

PATIENTS AND METHODS

The study included 81 patients with papillary thyroid cancer; they failed to achieve complete ablation after a first ablative dose of 3700 MBq. Their first follow-up (131)I whole-body scan carried out 6-9 months after ablation showed small residual functioning tissue in the thyroid bed, with no functioning metastases. This is associated with unsuppressed serum thyroglobulin level (Tg) higher than 2 ng/ml. The patients received a second ablation dose, which was low (1110 MBq) in 37 patients and high in the remaining 44 patients (2960 MBq in 36 patients and 3700 MBq in eight patients). A whole-body scan and Tg level assessment were carried out 6-9 months later. The criteria for complete ablation included absence of residual functioning thyroid tissue and a Tg level lower than 2 ng/ml.

RESULTS

The overall successful complete ablation rate after the second reablation dose was 75%. This was achieved in 27 of 37 patients (73%) who received a low reablation dose and in 34 of 44 patients (77%) who received a high reablation dose; no statistically significant difference was found between the two groups (P>0.05).

CONCLUSION

In patients with papillary thyroid cancer who failed to achieve complete ablation after the first ablation dose of 3700 MBq, the overall complete ablation rate after both a low and a high second (131)I dose was 75%, with no statistically significant difference in ablation rate between low (1110 MBq) and high (2960 and 3700 MBq) doses (73 and 77%, respectively).

Differentiated thyroid cancer in patients over 60 years of age at presentation: a retrospective study of 438 patients

OBJECTIVES

The aim of this study is to identify the prognostic factors predicting remission and subsequent disease relapse in patients with differentiated thyroid cancer (DTC) greater than 60years of age.

MATERIALS AND METHODS

The institute thyroid cancer database had 4370 patients with DTC, of which 447 (10%) were aged>60. However, 9 patients were excluded due to follow-up less than 1year. The prognostic factors in the remaining 438 patients were studied.

RESULTS

Among the 438 patients, 311 (71%) had only loco-regional disease (M0) and 127 (29%) had distant metastases (M1) at the time of initial presentation. The host factors predictive of distant metastases at presentation were female gender, primary tumor size (>4cm), follicular histology, and extra-thyroidal extension. Among Mo patients, 195 (63%) achieved complete remission while only 12 (9%) M1 patients did so. Average number of radioactive iodine ((131)I) doses administered to achieve complete remission was 2.3 (range, 1-6) and the mean cumulative dose was 3404MBq (range, 925-46,250MBq). In multivariate logistic regression among M0 patients, follicular histology, nodal metastases, and surgical treatment lesser than total/near-total thyroidectomy and among M1 patients, site of distant metastases (skeletal and multiple sites) were independent factors predicting non-remission. Among the patients (both M0 and M1) who achieved remission, factors associated with disease recurrence were primary tumor size (>4cm), nodal metastases, pulmonary metastases, and non-remission after first dose of radioactive iodine and were associated with greater chances of disease relapse.

CONCLUSION

This study highlights that DTC in older patients behaves more aggressively than in adults age<60years, and identifies several prognostic factors for remission and subsequent relapse.

Differentiated thyroid cancer-personalized therapies to prevent overtreatment

The concept of individualized therapy is rapidly gaining recognition in the management of patients with differentiated thyroid cancer (DTC). This Review provides an overview of the most important elements of this paradigm shift in DTC management and discusses the implications for clinical practice. In the majority of patients with DTC who have an inherently good prognosis, the extent of surgery, the dosage of (131)I therapy and the use of levothyroxine therapy are all aspects suitable for individualization, on the basis of both the stage of disease and the response to treatment. In individuals with advanced disease, newer imaging techniques, advances in (131)I therapy and the use of targeted molecular therapies (such as multitargeted kinase inhibitors) have provided new options for the personalized care of patients, for whom until recently no effective therapies were available. Individualized therapies could reduce adverse effects, including the sometimes debilitating hypothyroidism that used to be required before initiation of (131)I treatment, and major salivary gland damage, a common and unpleasant side effect of (131)I therapy. Highly individualized interdisciplinary treatment of patients with DTC might lead to improved outcomes with reduced severity and frequency of complications and adverse effects. However, in spite of ongoing research, personalized therapies remain in their infancy.

Stimulated Serum Thyroglobulin Level at the Time of First Dose of Radioactive Iodine Therapy Is the Most Predictive Factor for Therapeutic Failure in Patients With Papillary Thyroid Carcinoma

PURPOSE

To investigate the clinical importance of serum thyroglobulin (Tg) levels just before high-dose I-131 ablation therapy (preablation Tg) for predicting therapeutic failure in patients with papillary thyroid carcinoma (PTC).

METHODS

Patients with PTC (n = 132) undergoing total thyroidectomy followed by the first high-dose I-131 ablation therapy (HI-Rx) were included in this retrospective review. Just before HI-Rx, preablation Tg, anti-Tg antibody, and TSH were measured. The patients were followed up for a mean period of 7 months (range 6-23 months) by I-123 whole-body scans (f/u IWBS) and stimulated Tg (f/u Tg). Therapeutic failure was defined by positive f/u IWBS or f/u Tg >2 ng/ml. We classified patients into three groups according to the value of preablation Tg (group 1, <1 ng/ml; group 2, ≥1 and <10 ng/ml; group 3, ≥10 ng/ml) and compared clinical variables to therapeutic response.

RESULTS

Therapeutic failure was noted in 39 patients (29.5 %). On univariate analysis, T stage, tumor size, and preablation Tg were the statistically significant factors that could predict therapeutic failure. After multivariate analysis, preablation Tg was the only independent predictor of therapeutic failure (P < 0.001). The therapeutic failure rate was significantly increased as the preablation Tg level increased (11.3 %, 33.3 %, and 87.5 % in groups 1, 2, and 3, respectively; P < 0.001). Individuals with preablation Tg levels ≥10 ng/ml had 25.5 times greater chance of therapeutic failure than those with levels <10 ng/ml (95 % CI = 5.43-119.60; P < 0.001).

CONCLUSIONS

A high preablation Tg level is the most significant predictor of therapeutic failure at the time of first HI-Rx in patients with PTC.

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 I(131)remnant 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.

Current controversies in the initial post-surgical radioactive iodine therapy for thyroid cancer: a narrative review

Differentiated thyroid cancer (DTC) is the most common endocrine malignancy and the fifth most common cancer in women. DTC therapy requires a multimodal approach, including surgery, which is beyond the scope of this paper. However, for over 50 years, the post-operative management of the DTC post-thyroidectomy patient has included radioactive iodine (RAI) ablation and/or therapy. Before 2000, a typical RAI post-operative dose recommendation was 100 mCi for remnant ablation, 150 mCi for locoregional nodal disease, and 175-200 mCi for distant metastases. Recent recommendations have been made to decrease the dose in order to limit the perceived adverse effects of RAI including salivary gland dysfunction and inducing secondary primary malignancies. A significant controversy has thus arisen regarding the use of RAI, particularly in the management of the low-risk DTC patient. This debate includes the definition of the low-risk patient, RAI dose selection, and whether or not RAI is needed in all patients. To allow the reader to form an opinion regarding post-operative RAI therapy in DTC, a literature review of the risks and benefits is presented.

Radioiodine therapy for patients with differentiated thyroid cancer after thyroidectomy: direct comparison and network meta-analyses

BACKGROUND AND OBJECTIVES

The effective dose of radioiodine 131 (I-131) ablation for patients with differentiated thyroid cancer (DTC) after thyroidectomy was unclear, so we tried to find out which activity is the best using the methods of direct comparison and network meta-analyses.

METHODS

Direct comparison and network meta-analyses were conducted with ADDIS software. Randomized controlled trials (RCT) which compared different activities of I-131 after thyroidectomy for adult patients with DTC were included. The outcomes we evaluated were successful remnant ablation rate, duration of stay in an isolation unit, the number of subsequent I-131 treatments required, recurrence rate, and adverse effects.

RESULTS

Thirteen RCT (3352 patients) were included. Our network meta-analysis demonstrated that there were not any statistical differences in successful ablation rates among all comparisons except 100 mCi vs 15 mCi. However, rank probability plot suggested 60 mCi might be the best in successful ablation rate. For recurrence rate, both direct comparison and network meta-analyses showed no statistical differences among 100 mCi, 60 mCi, and 30 mCi; 100 mCi was associated with a smaller number of patients who required subsequent I-131 treatments and longer stay in an isolation unit than 30 mCi without any more adverse events.

CONCLUSION

Because of conflicting results between direct comparison and network meta-analyses, we failed to conclude which activity of I-131 is the best in successful ablation rates.

To treat or not to treat: the role of adjuvant radioiodine therapy in thyroid cancer patients

Radioactive iodine (RAI) is used in treatment of patients with differentiated papillary and follicular thyroid cancer. It is typically used after thyroidectomy, both as a means of imaging to detect residual thyroid tissue or metastatic disease, as well as a means of treatment by ablation if such tissue is found. In this paper, we discuss the indications for and the mechanisms of RAI in the treatment of patients with thyroid cancer. We discuss the attendant risks and benefits that come with its use, as well as techniques used to optimize its effectiveness as an imaging tool and a therapeutic modality.

Ablation with low-dose radioiodine and thyrotropin alfa in thyroid cancer

BACKGROUND

It is not known whether low-dose radioiodine (1.1 GBq [30 mCi]) is as effective as high-dose radioiodine (3.7 GBq [100 mCi]) for treating patients with differentiated thyroid cancer or whether the effects of radioiodine (especially at a low dose) are influenced by using either recombinant human thyrotropin (thyrotropin alfa) or thyroid hormone withdrawal.

METHODS

At 29 centers in the United Kingdom, we conducted a randomized noninferiority trial comparing low-dose and high-dose radioiodine, each in combination with either thyrotropin alfa or thyroid hormone withdrawal before ablation. Patients (age range, 16 to 80 years) had tumor stage T1 to T3, with possible spread to nearby lymph nodes but without metastasis. End points were the rate of success of ablation at 6 to 9 months, adverse events, quality of life, and length of hospital stay.

RESULTS

A total of 438 patients underwent randomization; data could be analyzed for 421. Ablation success rates were 85.0% in the group receiving low-dose radioiodine versus 88.9% in the group receiving the high dose and 87.1% in the thyrotropin alfa group versus 86.7% in the group undergoing thyroid hormone withdrawal. All 95% confidence intervals for the differences were within ±10 percentage points, indicating noninferiority. Similar results were found for low-dose radioiodine plus thyrotropin alfa (84.3%) versus high-dose radioiodine plus thyroid hormone withdrawal (87.6%) or high-dose radioiodine plus thyrotropin alfa (90.2%). More patients in the high-dose group than in the low-dose group were hospitalized for at least 3 days (36.3% vs. 13.0%, P<0.001). The proportions of patients with adverse events were 21% in the low-dose group versus 33% in the high-dose group (P=0.007) and 23% in the thyrotropin alfa group versus 30% in the group undergoing thyroid hormone withdrawal (P=0.11).

CONCLUSIONS

Low-dose radioiodine plus thyrotropin alfa was as effective as high-dose radioiodine, with a lower rate of adverse events. (Funded by Cancer Research UK; ClinicalTrials.gov number, NCT00415233.).

Thyroid carcinoma in children and adolescents-systematic review of the literature

Thyroid cancer in children and adolescents is usually a major concern for physicians, patients, and parents. Controversies regarding the aggressiveness of the clinical presentation and the ideal therapeutic approach remain among the scientific community. The current recommendations and staging systems are based on data generated by studies in adults, and this might lead to overtreating in some cases as well as undertreating in others. Understanding the differences in the biology, clinical course, and outcomes in this population is crucial for therapeutic decisions. This paper evaluates the biology, clinical presentation, recurrences, and overall survival as well as the staging systems in children and adolescents with differentiated thyroid cancer.