Detection of distant metastasis at the time of ablation in children with differentiated thyroid cancer: the value of pre-ablation stimulated thyroglobulin

Does it work in childhood and adolescence? The predictive role of postoperative/preablative stimulated thyroglobulin levels in paediatric thyroid cancer. A systematic review of the literature

BACKGROUND

Thyroglobulin is a well-established disease marker during follow-up in paediatric differentiated thyroid cancer. However, no conclusive data on the role of endogenously stimulated thyroglobulin after thyroidectomy (ptTg) in predicting disease-specific outcomes are available. This review aims to establish the prognostic value of ptTg in children with DTC.

METHODS

Online medical databases were searched for studies evaluating the association between ptTg and disease-specific outcomes in DTC-affected children. Documents not in English, preclinical studies, other review articles, case reports, and small case series were excluded. The risk of bias was assessed with the QUADAS-2 tool.

RESULTS

Twelve studies, analysing 1043 children in total, were included in the review. They all had a retrospective design and were published between 2016 and 2022. Of all patients, 1008 (97%) and 849 (81%) had undergone thyroidectomy and RAI, respectively. Eight studies (756 children) evaluated the correlation between ptTg and disease persistence/relapse: six reported a significant association between these parameters; a specific ptTg cut-off (10-14 ng/ml) was identified at the multivariate analysis in three studies. The remaining four studies assessed the link between ptTg levels and disease extension, with three reporting a correlation between ptTg and lung/nodal metastases.

DISCUSSION

ptTg is a readily available and inexpensive parameter, bearing a strong prognostic power in identifying disease persistence, relapse, and the presence of metastases in children affected by DTC.

Lymph node ratio independently associated with postoperative thyroglobulin levels in papillary thyroid cancer

OBJECTIVES

To investigate the impact of the lymph node ratio (LNR) on postoperative thyroglobulin (Tg) levels in patients with papillary thyroid carcinoma (PTC).

PATIENTS AND METHODS

This was a retrospective, cohort study. The association between clinicopathological variables and postoperative unstimulated Tg (uTg) levels, preablative-stimulated Tg (sTg) levels, and postablative unstimulated Tg levels was analysed.

RESULTS

A total of 300 patients with PTC were identified. Multivariate logistic analysis showed that M classification (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.62-3.34), and postoperative thyroid-stimulating hormone levels (OR, 1.01; 95% CI, 1.01-1.02) were independently associated with postoperative uTg levels. One hundred and sixteen patients underwent radioactive iodine (RAI) therapy. Multivariate analysis showed that LNR in the central neck (OR, 1.24; 95% CI, 1.02-1.51), LNR in the lateral neck (OR, 1.73; 95% CI, 1.09-2.77), RAI dose (OR, 1.43; 95% CI, 1.21-1.69), and M classification (OR, 1.79; 95% CI, 1.22-2.61) were independently associated with preablative sTg levels. Tumour size (OR, 1.01; 95% CI, 1.00-1.01), LNR in the central neck (OR, 1.28; 95% CI, 1.08-1.51), LNR in the lateral neck (OR, 1.66; 95% CI, 1.10-2.49), RAI dose (OR, 1.54; 95% CI, 1.34-1.79), and M classification (OR, 1.56; 95% CI, 1.12-2.19) were also independently associated with postablative uTg levels.

CONCLUSION

LNR was independently associated with postoperative Tg levels in patients with PTC. Patients with high LNR were more likely to have incomplete biochemical responses after surgery.

Establishing a Cutoff Serum Thyroglobulin Value for the Diagnosis and Management of Well-Differentiated Thyroid Cancer

Objective  The aim of this study was to define a cutoff serum thyroglobulin (Tg) level associated with either residual or metastasis that may help decide postoperative radioactive iodine (RAI) scan and treatment in differentiated thyroid cancer (DTC) patients residing in low-income countries like Nepal. Methods  We prospectively studied a total of 81 patients (female-to-male ratio of 3.0:1; mean age: 37.3 ± 14.0 years, within age range of 14-88 years) who underwent total thyroidectomy with/without neck dissection and were referred for RAI whole-body scan (WBS) ± RAI ablation or adjuvant treatment in the department of Nuclear Medicine, Chitwan Medical College. We calculated the cutoff value of Tg using receiver operating characteristic (ROC) curve analysis. Results  Forty-six of 81 patients (56.7%) had remnants in the thyroid bed, 26/81 (32.1%) had regional lymph node metastasis, 9/81 (11.1%) had distant lymph node metastasis, 3/81 (3.7%) had lung metastases, and only 1/81 (1.2%) had bone metastases. RAI WBS was positive in 61/81 (75.3%) patients and negative in 20/81 (24.7%) patients. Seventeen of 81 (20.9%) patients had negative RAI scans with low serum Tg levels; only 3/81 (3.7%) patients had Tg elevated negative RAI scan (TENIS). Although scan was positive in 61/81 (75.3%) patients, 64/81 (79.0%) patients received treatment with RAI, of which 3/81 (3.7%) patients were TENIS patients. There was a significant difference in serum Tg levels between patients who received or did not receive RAI ablation or treatment ( p  < 0.05). On ROC curve analysis, the cutoff value of Tg levels between patients who received and did not receive treatment was 2.9 ng/mL (sensitivity: 85.9%; specificity: 94.1%; positive predictive value [PPV], 98.2%; negative predictive value [NPV]: 64.0%; AUC: 0.938). Conclusion  We identified a cutoff value of 2.9 ng/mL between patients who required or did not require treatment with high sensitivity, specificity, and PPVs.

Long-term prognostic analysis of children and adolescents with differentiated thyroid carcinoma based on therapeutic response to initial radioiodine therapy

Background

The clinical features and prognosis of children and adolescents with differentiated thyroid carcinoma (caDTC) are different from that of adults. Postoperative radioiodine therapy (RIT) was recommended for some intermediate and high risk caDTC patients. The objective of this study was to evaluate the long-term prognosis of pediatric caDTC patients with different responses to initial RIT and to explore the related influencing factors.

Methods

All subjects were assigned to no clinical evidence of disease (NED) group, biochemical persistent disease (BPD) group, or structural/functional persistent disease (S/FPD) group based on the therapeutic response to initial RIT. Then, disease status was evaluated in all three groups at the last follow-up using ATA guidelines. Meanwhile, disease-free survival (DFS) for NED group and the progression-free survival (PFS) for the BPD and S/FPD groups were also assessed.

Results

117 subjects were divided into NED group (n=29), BPD group (n=48) and S/FPD group (n=34) after initial RIT. At the last follow-up, excellent response (ER), indeterminate response (IDR), biochemically incomplete response (BIR) and structurally incomplete response (SIR) rates were 93.10%, 6.90%, 0% and 0% in NED group; 29.17%, 25.00%, 43.75% and 2.08% in BPD group; and 11.77%, 2.94%, 0%, and 85.29% in S/FPD group. The 5-year DFS rate in NED group was 95.5%. The 5-year PFS rates in BPD and S/FPD groups were 79.2% and 48.6%, respectively. For children with structural or functional lesions, longer PFS were found in male children with 131I-avid lesions, and post-operative stimulated serum thyroglobulin (sti-Tg) < 149.80 ng/ml.

Conclusion

The response to initial RIT could be helpful for defining subsequent treatment and follow-up strategies for caDTC patients. Post-operative sti-Tg and 131I-avidity of lesions are correlated with PFS.

The Prognostic Impact of Extent of Vascular Invasion in Follicular Thyroid Carcinoma

BACKGROUND

Encapsulated angioinvasive follicular thyroid carcinoma (EAFTC) is associated with an increased risk of distant metastasis and reduced survival compared to minimally invasive follicular thyroid carcinoma (MIFTC). There is controversy regarding the extent of surgery and adjuvant radioactive iodine therapy for angioinvasive follicular thyroid carcinoma when stratified by number of foci of angioinvasion.

METHODS

All follicular thyroid carcinoma cases from 1990-2018 were identified from a thyroid cancer database. Primary outcomes were distant metastasis-free survival (DMFS) and disease-specific survival (DSS) with factors of interest being age, gender, tumour size, treatment, foci of angioinvasion and histological subtype.

RESULTS

A total of 292 cases were identified; 139 MIFTC, 141 EAFTC and 12 widely invasive follicular thyroid carcinoma (WIFTC). Over a follow-up period of 6.25 years, DMFS was significantly reduced (p < 0.001) with 14.2% (EAFTC) and 50% of WIFTC developing metastasis. The risk of metastasis in EAFTC with ≥ 4 foci of angioinvasion was 31.7% (HR = 5.89, p = 0.004), 6.3% for EAFTC with < 4 foci of angioinvasion (HR = 1.74, p = 0.47), compared to 3.6% MIFTC. Age ≥ 50 years (HR = 4.24, p = 0.005) and tumour size (HR = 1.27, p = 0.014) were significantly associated with increased risk of distant metastasis. DSS was reduced significantly (p < 0.001), with 7.8% EAFTC patients dying of disease. For EAFTC patients, DSS was 96.8% for < 4 foci and 82.6% for ≥ 4 foci of angioinvasion (p = 0.003).

CONCLUSION

EAFTC is at increased risk of distant metastasis related to the extent of angioinvasion. Tumours with < 4 foci of angioinvasion should be considered for a total thyroidectomy, particularly in older patients.

Differentiated Thyroid Cancer in a Pediatric Population: Estimating the Risk of Recurrence and Evolution Over Time

Background Differentiated thyroid cancer (DTC) is the most common endocrine cancer during childhood, and the prognosis is usually good. The 2015 American Thyroid Association (ATA) pediatric guidelines for DTC classify patients into three categories (low, intermediate, and high) that represent the risk for persistent/recurrent disease. The "Dynamic Risk Stratification" (DRS) System showed that, in adults, reassessment of disease status during follow-up was a better predictor of disease status at the end of follow-up when compared to ATA risk stratification. This system is still not validated for the pediatric population with DTC. Our aim was to evaluate the usefulness of the DRS system in predicting DTC disease behaviour in this specific population. We also aimed to evaluate potential clinical-pathological factors associated with persistent disease at the end of follow-up. Methods A retrospective analysis of 39 pediatric patients (≤18 years) with DTC was conducted in our institution between 2007 and 2018, including 33 patients who had follow-up ≥ 12 months; these were classified into ATA risk groups and re-stratified according to their response to treatment at 12-24 months of follow-up. The associations between the ordinal variables of the baseline ATA risk group and the disease status re-evaluated 12-24 months after diagnosis (as per the DRS system) and at the end of follow-up were evaluated using a linear-by-linear association test. Gender, age at diagnosis, tumor size, multicentricity, extrathyroid extension, vascular invasion, lymph node metastasis, distant metastasis, and stimulated thyroglobulin (sTg) during the first RAI administration were evaluated as potential factors associated with persistent disease at 27 months after diagnosis using Firth's bias-reduced penalized-likelihood logistic regression. Results In this study, 39 patients were retrospectively analyzed, including 33 patients who had follow-ups ≥ 12 months with a median time of 56 (27-139) months who were classified in ATA risk groups and then re-stratified depending on their response to treatment between 12 and 24 months of follow-up. There was a statistically significant association between ATA risk groups and re-evaluation at 12 and 24 months (p=0.001) and between these two stratifications and the state of disease at final follow-up (p<0.001 for both). Factors with a statistically significant association with persistent disease at 27 months of follow-up were male sex, lymph node metastases at diagnosis, distant metastasis, extrathyroidal extension, and stimulated Tg values. Conclusions The assessment of the response to treatment between 12 and 24 months and at the end of follow-up refines the initial ATA risk stratification, confirming that dynamic risk evaluation is also helpful in the pediatric population.

Prognostic factors in children and adolescents with differentiated thyroid carcinoma treated with total thyroidectomy and RAI: a real-life multicentric study

PURPOSE

This multicentric study aimed to investigate the main prognostic factors associated with treatment response at 1 year after radioactive iodine therapy (RAIT) and the last disease status in pediatric patients affected by differentiated thyroid carcinoma (DTC).

MATERIALS AND METHODS

In the period 1990-2020, all consecutive patients ≤ 18 years from six different centers were retrospectively included. Patients were classified as low, intermediate, and high risk for persistence/recurrence. The response to RAIT was evaluated and scored 1 year later according to 2015 ATA guidelines. Moreover, at the last follow-up, the disease status was evaluated and dichotomized as no evidence of disease (NED) or persistent disease.

RESULTS

Two hundred and eighty-five patients (197 female, 88 male; mean age 14.4 years) were recruited. All, except nine, underwent near-total thyroidectomy followed by RAIT. One-year after first RAIT, 146/276 (53%) patients had excellent response, 37/276 (14%) indeterminate response, and 91/276 (33%) incomplete response. One-year after RAIT, children with excellent response had significantly lower stimulated thyroglobulin (sTg) compared to not excellent group (median sTg 4.4 ng/ml vs 52.5 ng/ml, p < 0.001). ROC curve showed sTg higher than 27.2 ng/ml as the most accurate to predict 1-year treatment response. After a median follow-up of 133 months, NED was present in 241 cases (87%) while persistent disease in 35 (13%). At multivariate analysis, sTg and 1-year treatment response categories were both significantly associated with the last disease status (p value 0.023 and < 0.001).

CONCLUSIONS

In pediatric DTC, sTg is significantly associated with 1-year treatment response and final outcome. However, 1-year response is the principal prognostic factor able to predict pediatric DTCs outcome.

Retrospective analysis of clinical characteristics and risk factors of differentiated thyroid cancer in children

BACKGROUND

The incidence rate of children with thyroid cancer has an increasing trend. This study aimed to investigate the clinical characteristics and therapeutic approaches of differentiated thyroid cancer (DTC) in Chinese children.

MATERIALS AND METHODS

From January 1998 to March 2022, 52 cases undergoing surgical resection in Xinhua Hospital affiliated to Shanghai Jiao Tong University were divided by age (≤ 7 years old: n = 14 and 8-13 years old, n = 38). Treatment methods and clinical features were analyzed to evaluate prognostic factors for oncological outcomes.

RESULTS

Among the 52 cases, the proportion of local invasion in the pre-school group was found to be higher than that in the school-age group (p = 0.01). T stage was significantly different between the two groups (p ≤ 0.05); the proportion of T_1-2 was higher in the school-age group (32 cases, 84.2%), while the proportion of T₄ was higher in the pre-school group (6 cases, 42.8%) relatively. The postoperative complication rate was dramatically higher in pre-school children (p ≤ 0.05). Additionally, the total thyroidectomy rate in the non-recurrent group was slightly higher than that in the recurrent group (p ≤ 0.05). Over half of the recurrent cases had low T stage and low ATA (American Thyroid Association) risk levels at initial diagnosis (78.3 and 51.4%).

CONCLUSION

The local invasion, tumor stage, and recurrent laryngeal nerve (RLN) injury rates of the pre-school group were higher than that of the school-age group, where young age served as a potential hazard in DTC children. Hence, surgeons should emphasize high-risk features and optimize individualized surgical procedures for DTC children.

The Role of Thyroglobulin in Preoperative and Postoperative Evaluation of Patients With Differentiated Thyroid Cancer

Thyroglobulin (Tg) is secreted by thyroid follicular cells and stored in the thyroid follicular lumen as a component of thyroid hormone. It is known that both benign and well-differentiated malignant thyroid tissue can secrete Tg. In recent years, growing lines of evidence have shown that Tg plays an important role in the diagnosis and metastasis of preoperative differentiated thyroid carcinoma (DTC). The levels of Tg, whether in the serum or in a fine-needle aspiration washout fluid, are usually viewed as an excellent indicator in the monitoring of postoperative DTC, including the guidance and evaluation of radioactive iodine ablation. Nevertheless, some factors limit the application of Tg, such as the method used to measure Tg and the presence of Tg antibodies. This review aimed to summarize the role of Tg in the preoperative and postoperative evaluation of patients with DTC, and the factors influencing Tg. This review could provide a reference for a more accurate application of Tg in patients with DTC.

Clinical applications of single-photon emission computed tomography/computed tomography in post-ablation 131iodine scintigraphy in children and young adults with differentiated thyroid carcinoma

BACKGROUND

The utility of integrated single-photon emission computed tomography/computed tomography (SPECT/CT) in children and young adults with differentiated thyroid carcinoma is incompletely studied.

OBJECTIVE

To determine the value of adding SPECT/CT to conventional whole-body scintigraphy in post-ablation iodine-131 (¹³¹I) scintigraphy for children and young adults with differentiated thyroid carcinoma.

MATERIALS AND METHODS

Planar scintigraphy and SPECT/CT were performed on 42 post-surgical children and young adults (32 female, 10 male; mean age 14.3±4.9 years, range 7-20 years) with differentiated thyroid carcinoma (39 papillary, 2 follicular, 1 mixed) 5 days after the therapeutic administration of 1.9-7.4 GBq of ¹³¹I. Planar and SPECT/CT images were interpreted independently, and sites of uptake were categorized as positive or equivocal with respect to thyroid bed, lymph node and distant metastasis uptake. An experienced thyroid endocrinologist used a combination of surgical histopathology and scintigraphic findings to determine whether the addition of SPECT/CT would change patient management.

RESULTS

Planar scintigraphy evidenced 88 radioiodine-avid foci and SPECT/CT confirmed all foci. No additional foci were disclosed by SPECT/CT. SPECT/CT correctly classified 16/88 (18%) foci that were unclear or wrongly classified at planar scintigraphy. Globally, SPECT/CT showed an incremental value over planar scintigraphy in 9 (21.4%) patients and changed therapeutic management in 3 (7.1%; 95% confidence interval, 2-20%) patients.

CONCLUSION

SPECT/CT improved localization and characterization of focal ¹³¹I uptake on post-ablation whole-body scintigraphy in children and young adults with differentiated thyroid carcinoma. Further prospective evaluation in a larger series is justified to prove the effect of post-ablation SPECT/CT-based management decisions.

Long-term outcome of differentiated thyroid cancer in children and young adults: risk stratification by ATA criteria and assessment of pre-ablation stimulated thyroglobulin as predictors of disease persistence

PURPOSE

Differentiated thyroid cancer (DTC) has an increasing incidence in childhood and adolescence but long-term outcome data are limited. We aimed to identify possible risk factors associated with disease persistence, with special focus on the usefulness of ATA risk stratification system and pre-ablation stimulated thyroglobulin (Tg) levels.

METHODS

We retrospectively studied 103 patients, 79 females (76.7%), aged 15.6 ± 3.2 years (range 5-21 years) who underwent total thyroidectomy for DTC. Patients were classified by ATA risk stratification criteria as low, intermediate, and high risk for recurrence. All, except five with papillary microcarcinoma, received radioactive iodine (RAI) treatment.

RESULTS

At diagnosis, 44.7% of patients had cervical lymph node and 7.8% pulmonary metastases. Amongst the 72 patients with long-term follow-up data, 31.9% had persistent disease. Lymph node as well as pulmonary metastases and increased pre-ablation stimulated thyroglobulin (Tg) levels were associated with persistent disease. The risk of persistent disease was significantly higher in both the intermediate- (OR 17.95; 95% CI 2.66-120.94, p < 0.01) and high-risk (OR 17.65; 95% CI 4.47-69.74, p < 0.001) groups. ROC curve analysis showed that a pre-ablation Tg level higher than 14 ng/ml had a sensitivity of 94.7% to predict persistence, corresponding to a positive (PPV) and negative predictive values (NPV) of 66.7% and 93.8%, respectively.

CONCLUSIONS

ATA risk stratification was validated in our population of children and young adults with DTC. Moreover, pre-ablation stimulated Tg levels of <14 ng/ml were associated with a low risk of long-term persistence and may therefore serve as a marker to identify patients who may need less intensive surveillance.

A cutoff thyroglobulin value suggestive of distant metastases in differentiated thyroid cancer patients

Serum thyroglobulin is used as part of the early postoperative assessment of differentiated thyroid cancer (DTC) since there is a clear relationship between an increased risk of recurrence and persistent disease after initial treatment and high postoperative stimulated thyroglobulin (ps-Tg) values. Thus, although ps-Tg above 10-30 ng/mL is considered an independent predictor of worse prognosis, the value that is associated with distant metastases is not defined. Thus, this was our objective. We selected 655 DTC patients from a nuclear medicine department database (Irmandade Santa Casa de Misericórdia de São Paulo, Brazil). All patients had received total thyroidectomy and radioactive iodine (RAI) therapy and had ps-Tg values higher than 10 ng/mL with negative anti-thyroglobulin antibodies. Then, we selected patients who presented post-therapy whole-body scan with pulmonary and/or bone uptake but with no mediastinum or cervical uptake. Patients with negative findings on functional imaging or any doubt on lung/bone uptake were submitted to additional exams to exclude another non-thyroid tumor. Of the 655 patients, 14.3% had pulmonary and 4.4% bone metastases. There was a significant difference in ps-Tg levels between patients with and without metastases (P<0.001). The cutoff value of ps-Tg was 117.5 ng/mL (sensitivity: 70.2%; specificity: 71.7%) for those with lung metastasis, and 150.5 ng/mL (sensitivity: 79.3%; specificity: 85%) for those with bone metastasis. The cutoff value for patients with eitherpulmonary or bone metastasis was 117.5 ng/mL (sensitivity: 70.2%; specificity: 83.7%). Our findings demonstrated that ps-Tg could predict distant metastasis in DTC patients. We identified a cutoff of 117.5 ng/mL with a high negative predictive value of 93.7%.

Prognostic Value of Pre-Ablation Stimulated Thyroglobulin in Children and Adolescents with Differentiated Thyroid Cancer

Purpose: To systemically investigate the prognostic value of pre-ablation stimulated thyroglobulin (s-Tg) in children and adolescents with differentiated thyroid cancer. Methods: Clinical records from 118 children and adolescents were retrospectively reviewed. Results: The median age was 16 years, and the majority were female (79.7%). All children and adolescents underwent total thyroidectomy and received radioactive iodine therapy. After a median follow-up of 5.3 years, 68 (57.6%) patients were disease free, while 50 patients (42.4%) had persistent/recurrent disease. In multivariate analysis, pre-ablation s-Tg and M1 were the independent predictive factors for persistent/recurrent disease. According to the receiver operating curve analysis, the best pre-ablation s-Tg cutoff to predict disease-free status was 17.8 ng/mL with a negative predictive value of 96.8%. Integration of pre-ablation s-Tg into American Thyroid Association pediatric risk categories indicated that the presence of pre-ablation s-Tg ≤17.8 ng/mL was associated with a decreased chance of having persistent/recurrent disease in intermediate- and high-risk patients (22.6% to 2.6% in intermediate-risk patients, and 64.4% to 5.6% in high-risk patients). Conclusions: Our findings suggest that pre-ablation s-Tg has the capability of predicting the clinical outcomes in children and adolescents with thyroid cancer.

Physiologic Uterine Uptake of Radioiodine During Menstruation Demonstrated by SPECT/CT

A 35-year-old woman with papillary thyroid cancer underwent I therapy after thyroidectomy. Post-therapy whole body scan revealed increased activity in the pelvis, in addition to the activity in the neck. On SPECT/CT images, the radioactivity in the pelvis was localized in the rectum and cervix. Further inquiry discovered that the patient was menstruating. We concluded that abnormal radioiodine uptake in menstrual uterus might be an exceptional finding mimicking a metastasis.

An Unusual False-Positive Uptake of Radioiodine Caused by Metallic Implants

A 36-year-old woman with a history of papillary thyroid cancer underwent radioiodine remnant ablation using I. Postablation whole body I scintigraphy revealed increased activity not only in the thyroid bed but also in the right upper thigh. SPECT/CT images localized the activity to the metallic implants of the right femur, implanted 3 years earlier after the right femoral cyst resection.

Is TSH suppression still necessary in intermediate- and high-risk papillary thyroid cancer patients with pre-ablation stimulated thyroglobulin <1 ng/mL before the first disease assessment?

OBJECTIVE

Since papillary thyroid cancer (PTC) patients with pre-ablation stimulated thyroglobulin (s-Tg) < 1 ng/mL generally have a favorable prognosis, is TSH suppression still necessary in intermediate- and high-risk PTC patients with pre-ablation s-Tg < 1 ng/mL after initial therapy? The aim of this study was to assess the rate of disease recurrence in intermediate- and high-risk PTC patients with pre-ablation s-Tg < 1 ng/mL according to TSH levels measured 1 year after initial therapy.

METHODS

A retrospective series of intermediate- and high-risk PTC patients with pre-ablation s-Tg < 1 ng/mL was analyzed. Disease status was defined as the presence or absence of structural disease during late follow-up. Patients were grouped according to TSH level at 1 year: group 1, TSH < 0.1 mIU/L; group 2, TSH 0.1‒0.5 mIU/L; group 3, 0.5‒2 mIU/L; group 4, >2 mIU/L.

RESULTS

This study included 166 patients (78.3% females, median age 44 years) of whom the risk of recurrence was intermediate in 97 (58.4%) and high in 69 (41.6%). The response to initial therapy at 1 year was excellent in 163 patients (98.2%) and indeterminate in 3 (1.8%). Group 1 consisted of 63 patients (38%), group 2 of 47 (28%), group 3 of 28 (17%), and group 4 of 28 (17%). During a median follow-up duration of 5.8 years, disease recurrence was observed in only 4 patients (2.4%). The rate of disease recurrence was not significantly different between the TSH groups.

CONCLUSION

TSH suppression before the first response to treatment assessment does not seem to influence the rate of disease recurrence after initial therapy in intermediate- and high-risk PTC patients with pre-ablation s-Tg < 1 ng/mL.

Remarkable Response of Pulmonary Metastases Rather Than Remnant Thyroid in 131I Therapy of Follicular Thyroid Cancer

A 66-year-old man with follicular thyroid cancer after total thyroidectomy was referred for I therapy. Thyroid function tests before I administration exhibited severe thyrotoxicosis although the patient did not take levothyroxine after thyroidectomy. A 185 MBq I whole-body scintigraphy and SPECT/CT revealed multiple iodine-avid pulmonary metastases with the largest tumor diameter of 1.4 cm and remnant thyroid. A diagnosis of thyrotoxicosis caused by hyperfunctioning pulmonary metastases was then made. The patient was administered 7.4 GBq of I. Six months after I therapy, a significant reduction of the pulmonary metastatic disease and thyroglobulin level was observed. However, the remnant thyroid was still visualized.