Diagnostic Whole-body Scan Research Articles

Thyroid lobe ablation with iodine-131 in patients with differentiated thyroid carcinoma

The present study was undertaken to evaluate the ablation rate after administration of 1.1 or 3.7 GBq of iodine- (¹³¹I) to patients with low-risk differentiated thyroid carcinoma (DTC) primarily treated by lobectomy. Enrolled were 136 consecutive patients affected by histologically proven low-risk DTC previously treated by lobectomy. Patients were randomized to receive a single dose of 1.1 or 3.7 GBq of ¹³¹I in an equivalence trial. Successful thyroid ablation was defined as a negative diagnostic whole-body scan and stimulated thyroglobulin levels lower than 2 ng/ml in the absence of thyroglobulin antibodies. The patient demographic and clinical data were well balanced at baseline. The ablation rate was significantly (P<0.01) higher in patients treated with 3.7 GBq (75%) than in those treated with 1.1 GBq (54%) of radioiodine. No relevant side effects occurred in either group. Radioiodine lobe ablation with a single administration of 3.7 GBq is a simple and safe mode of treatment, achieving an ablation rate higher than that of 1.1 GBq. This procedure may be offered as an alternative to completion thyroidectomy in highly selected DTC patients who had experienced complications during initial surgery or for whom completion thyroidectomy is contraindicated.

False-positive Iodine-131 whole-body scan findings in patients with differentiated thyroid carcinoma: Report of 11 cases and review of the literature

BackgroundIodine-131 (I-131) whole-body scan (WBS) plays an important role in the management of patients with differentiated thyroid carcinoma (DTC), to detect normal thyroid remnants and recurrent or metastatic disease. A focus of I-131 accumulation outside the thyroid bed and the areas of physiological uptake is strongly suggestive of a distant functioning metastasis. However, many false-positive I-131 WBS findings have been reported in the literature. Patient findingsWe describe a series of 11 personal cases of patients with DTC, collected from 1992 to 2011, in whom diagnostic or post-treatment WBS showed false-positive retention of I-131 in various locations. SummaryFalse-positive accumulations of I-131 on WBS may be classified according to the underlying pathophysiological mechanisms: external and internal contaminations by body secretions, ectopic normal thyroid and gastric tissues, inflammatory and infectious diseases, benign and malignant tumors, cysts and effusions of serous cavities, thymic uptake, and other non classified causes. ConclusionsClinicians must be aware of possible false-positive findings to avoid misinterpretations of the I-131 WBS, which could lead to inappropriate treatments.

Postoperative-stimulated serum thyroglobulin measured at the time of 131I ablation is useful for the prediction of disease status in patients with differentiated thyroid carcinoma

This study was conducted to identify the relevant cutoff value and to evaluate the usefulness of postoperative-stimulated serum thyroglobulin (Tg) at the time of (131)I ablation for the prediction of disease status in patients with differentiated thyroid carcinoma (DTC) who received high-dose (131)I ablation therapy after total thyroidectomy. We analyzed 218 consecutively enrolled patients who were diagnosed with DTC and underwent total thyroidectomy. All patients underwent (131)I ablation at doses of 100-200 mCi, and stimulated serum Tg was measured at the time of (131)I ablation therapy. To assess disease-free status after (131)I ablation therapy, stimulated serum Tg levels, diagnostic whole-body scan (DxWBS) and neck ultrasonography (US) were performed 6-12 months after (131)I ablation. The relevant cutoff value of postoperative stimulated Tg for the prediction of disease-free status was 2 ng/mL. A total of 138 patients (63.3%) showed values of <2 ng/mL. Postoperative-stimulated Tg < 2 ng/mL had a negative predictive value of 94.9%, which increased to 97.7% when low Tg was combined with negative neck US findings. Postoperative-stimulated Tg at the time of (131)I remnant ablation is a useful biochemical marker for the prediction of disease status in patients with DTC. When high-dose (131)I remnant ablation is performed after total thyroidectomy, the stimulated Tg measurement and DxWBS that are usually performed 6-12 months after (131)I ablation therapy may be skipped, at least in low- and intermediate-risk patients with postoperative stimulated Tg of < 2 ng/mL and negative neck US findings.

The Effects of the Factors Related to the Patient and the Disease on the Performance of Ablation Therapy in Patients with Differentiated Thyroid Cancer who have Received I-131 Ablation Therapy

Objective: To investigate whether the factors related to the patient and the disease have any effect on the success of ablation therapy in patients with differentiated thyroid cancer who have received I-131 ablation therapy.Material and Methods: All the patients with differentiated thyroid cancer were referred for I-131 ablation therapy after thyroidectomy between July 2007 and September 2009. The patients had at least six months of follow-up. Age, gender, type of tumor, presence of capsule invasion, size of tumor, number of the tumors, localization of the tumor, invasion of thyroid capsule, lymph/vessel invasion, presence of metastatic lymph nodes, type of surgery, preablation values of thyroglobulin (Tg), AntiTg, TSH, surveys for the evaluation of metastatic disease, (thyroid and bone scintigraphy, neck and abdominal ultrasonography, chest and brain computerized tomography), administered dose, postablation I-131 whole body scan (WBS) and diagnostic I-131 WBS, neck USG, values of Tg and AntiTg at the 6th month were recorded. The presence of residual thyroid activity on the 6th month diagnostic I-131 WBS image was accepted as the criterion for ablation success.Results: 191 patients with differentiated thyroid cancer were assessed in this study. The overall success rate of the first ablation therapy was 74.3%. The success rate of the ablation therapy was 66% and 75% in metastatic group and non-metastatic group, respectively. Except the significant correlation between the number of pathologic lymph nodes and the success of ablation (p=0.025), there was no other significant correlation between the patient/disease related factors and the success of ablation therapy.Conclusion: Significant correlation between the number of the pathologic lymph nodes and the ablation therapy performance can also be due to statistical error because of the limited sample size. There was no significant correlation between other patient/disease related prognostic factors and the success of ablation therapy.Conflict of interest:None declared.

Effect of Prophylactic Central Compartment Neck Dissection on Serum Thyroglobulin and Recommendations for Adjuvant Radioactive Iodine in Patients with Differentiated Thyroid Cancer

Controversy exists in the management of patients with differentiated thyroid cancer (DTC). The purpose of this study was to examine the effect of prophylactic central compartment neck dissection (CCND) on serum thyroglobulin (Tg) levels and recommendations for adjuvant radioactive iodine (RAI). The records of 103 patients who underwent completion/total thyroidectomy for DTC between January 2009 and November 2010 were reviewed. Prophylactic CCND was defined as removal of central compartment lymph nodes with no preoperative or intraoperative evidence of lymphadenopathy. Institutional protocol included a diagnostic whole-body scan before RAI; patients with a negative scan and Tg < 2.0 did not receive adjuvant RAI. Among the 103 patients, therapeutic CCND was performed in 17 (17 %) and prophylactic CCND in 49 (48 %). Of the 49 patients, 20 (41 %) had positive cervical lymph nodes. Positive lymph nodes changed American Joint Committee on Cancer tumor, node, metastasis staging in 17 patients and recommendations for RAI in 14. At a median follow-up of 21 months, there was no difference in Tg level based on the application of CCND; however, 92 % of patients with M0 disease had an undetectable Tg. One patient had recurrent DTC based on serum Tg only. Prophylactic CCND resulted in detection of unsuspected metastatic lymphadenopathy in 20 (41 %) of 49 patients and changed RAI recommendations in 14 (33 %). To date, most patients have an undetectable Tg. Longer follow-up is needed to detect potential differences in recurrent disease based on the use of CCND or long-term effects of RAI.

Value of Diagnostic Radioiodine Whole-body Scanning after Initial Therapy in Patients with Differentiated Thyroid Cancer at Intermediate and High Risk for Recurrence

Value of Diagnostic Radioiodine Whole-body Scanning after Initial Therapy in Patients with Differentiated Thyroid Cancer at Intermediate and High Risk for Recurrence

Clinical Outcomes Following Empiric Radioiodine Therapy in Patients with Structurally Identifiable Metastatic Follicular Cell–Derived Thyroid Carcinoma with Negative Diagnostic But Positive Post-Therapy 131I Whole-Body Scans

While radioiodine (RAI) therapy remains the most effective treatment modality for RAI-avid distant metastatic follicular cell-derived thyroid cancer, the therapeutic utility of empiric RAI therapy in patients with structurally identifiable distant metastases that demonstrate RAI avidity only on the post-therapy scan (negative diagnostic whole-body scan [DxWBS]) remains uncertain. We report a retrospective assessment of the structural response to RAI therapy in 27 patients (median age 54 years, 59% male) with metastatic thyroid cancer (45% classical papillary thyroid cancer, 21% poorly differentiated, 15% tall-cell variant, 15% follicular variant, and 4% Hurthle cell carcinoma) with structurally identifiable distant metastases (86% pulmonary metastases) in whom a properly conducted DxWBS was negative, and the post-therapy scan showed RAI-avid metastatic lesions at the time of RAI remnant ablation. In response to the initial RAI ablation, none of the selected patients demonstrated structural disease regression, and no patient was rendered free of disease. However, 12 patients (44%) demonstrated stable lesions on serial structural imaging after an RAI ablation. Structural disease progression was seen in the remaining 56% (15/27), a median of 6 months after ablation. Unfortunately, additional RAI therapies given to 12/15 patients with progressive disease and 5/12 patients with stable lesions failed to cause structural disease regression, cure, or conversion from progressive to stable disease in any patient. All of the disease-specific deaths (7/27) were in patients who had structural disease progression (n=15) in response to RAI ablation. None of the patients with persistent but stable lesions on structural imaging (n=12) have died of thyroid cancer over a median follow-up period of 3.7 years. While 44% of patients with the DxWBS-negative/post-therapy scan-positive macroscopic distant metastasis will have stable cross-sectional imaging after RAI remnant ablation, the other 56% will demonstrate structural disease progression that cannot be effectively treated with repeated empiric RAI activities. Furthermore, the high disease-specific mortality rate seen within the first few years of remnant ablation in this small subset of patients with persistent progressive disease despite a positive post-therapy RAI scan argues that treatments other than repeated empiric RAI dosing be strongly considered.

Reply: Utility of Diagnostic Whole-Body Iodine Scanning in High-Risk Differentiated Thyroid Carcinoma

REPLY: We would like to thank our colleagues for their interest in and extensive evaluation of our article ([1][1]). We realize that this subject raises questions, and we tried to answer most of them in our article. Dam et al. have some points of criticism that we will address. We concluded that

Recombinant Human Thyroid Stimulating Hormone in Thyroid Remnant Ablation With 1.1 GBq 131Iodine in Low-Risk Patients

To evaluate the efficacy of recombinant human thyroid stimulating hormone [rhTSH (versus hypothyroidism)] in thyroid ablation with an activity of 1.1 GBq (30 mCi) (131)I. A total of 102 patients with thyroid cancer who fulfilled the following criteria were studied: submitted to total thyroidectomy with complete tumor resection; tumor ≤4 cm without extrathyroid invasion or lymph node metastases; negative anti-thyroglobulin (anti-Tg) antibodies. Thirty-two patients (group A) received 0.9 mg of rhTSH for 2 consecutive days followed by (131)I administration and 70 patients (group B) were prepared by levothyroxine withdrawal for 4 weeks. The groups were similar in sex, age, and tumor characteristics. Ablation was successful (stimulated Tg<1 ng/mL and negative diagnostic whole-body scanning and neck ultrasonography 9 to 12 mo after ablation) in 27 patients of group A (84.3%) and in 58 of group B (83%). Considering patients with Tg greater than 1 ng/mL immediately before (131)I administration, the rates were 72.2% in group A and 75% in group B. In group A, the ablation rate was similar for patients who discontinued levothyroxine-T4 3 days before (131)I administration and those maintained on hormone therapy. The mean follow-up was 29.6 months in group A and 55 months in group B. Stimulated Tg (after rhTSH) was undetectable in 29 patients of group A (90.6%) and in 61 of group B (87%) and 1 patient of group B presented cervical metastases at the last assessment. Low (131)I activity after rhTSH is effective for remnant ablation in patients who are at low risk of recurrence.

Utility of Diagnostic Whole-Body Iodine Scanning in High-Risk Differentiated Thyroid Carcinoma

TO THE EDITOR: de Meer et al. recently published a retrospective study comparing diagnostic whole-body scintigraphy (DxWBS) to stimulated thyroglobulin measurement in patients with high-risk differentiated thyroid cancer ([1][1]). The authors concluded that DxWBS offered no additional information

Recombinant Human TSH for Thyroid Remnant Ablation with 131I in Children and Adolescents with Papillary Carcinoma

Background: The objective of this study was to report the results of a series of 12 patients with papillary carcinoma aged 16 years or younger, who were prepared with recombinant human TSH (rhTSH) for remnant ablation with ¹³¹I. The TSH levels achieved and the safety of 24 cycles of rhTSH administration (ablation and control assessment) are reported. Methods: All patients were prepared using the same protocol as recommended for adults. Eight to 12 months after initial therapy, the patients were submitted to neck ultrasound, measurement of stimulated Tg and anti-Tg antibodies (TgAb), and diagnostic whole-body scanning (DxWBS). Results: TSH levels >50 mIU/l were achieved in all patients. An adverse reaction (mild nausea and headache) was observed in 1/24 cycles (4.1%). Eight (88.8%) of 9 patients with uptake in the thyroid bed in post-therapy whole-body scanning (RxWBS) achieved complete remission. One patient presented TgAb in the absence of apparent disease. In addition, imaging methods showed no apparent disease in the 2 patients with lymph node metastases in RxWBS. Elevated Tg persisted in 1 patient with pulmonary micrometastases. Conclusion: The present results demonstrate the efficacy and safety of rhTSH in children and adolescents.

Role of [18F]-Fluorodeoxy-D-Glucose Positron Emission Tomography and Computed Tomography in the Early Detection of Persistent/Recurrent Thyroid Carcinoma in Intermediate-to-High Risk Patients Following Initial Radioactive Iodine Ablation Therapy

Positron emission tomography/computed tomography (PET/CT) scan has a role in the surveillance of patients with a history of thyroid carcinoma. Its efficacy after remnant ablation as far as detecting persistent or recurrent thyroid carcinoma before other surveillance methods is not known, however. In intermediate-to-high risk thyroid carcinoma patients we studied whether PET/CT scan, performed 6-12 months after the first remnant ablation, could provide more information than ultrasonography (US) and thyrotropin-stimulated serum thyroglobulin (Tg) determination with diagnostic whole-body scan (DxWBS). We studied 71 subjects with differentiated thyroid cancer (DTC) who were intermediate-to-high risk for persistent/recurrent disease and who had received PET/CT scan, US, and DxWBS simultaneously with stimulated Tg levels 6-12 months after remnant ablation. To evaluate the diagnostic efficacy of PET/CT scan, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were calculated. Ten subjects (14%) had persistent/recurrent disease detected 6-12 months after remnant ablation. Persistence/recurrence was detected in nine (12.7%) of these patients by conventional methods, including US and DxWBS, along with stimulated Tg levels. The remaining case was detected solely by a PET/CT scan, which showed a mediastinal prevascular lesion; this was confirmed by a therapeutic WBS after additional radioiodine therapy. Among the six patients whose PET/CT scan showed positive results, five had persistent/recurrent disease. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of PET/CT scan for detecting persistent/recurrent thyroid carcinoma were 50%, 98.4%, 83.3%, 92.3%, and 91.5%, respectively. In intermediate-to-high risk patients with DTC seen 6-12 months after their first remnant ablation, there is almost no complementary role for adding a PET/CT scan to conventional follow-up methods, an US and a DxWBS simultaneously with stimulated Tg levels.

The Value of Diagnostic Whole-Body Scanning and Serum Thyroglobulin in the Presence of Elevated Serum Thyrotropin During Follow-Up of Anti-Thyroglobulin Antibody–Positive Patients with Differentiated Thyroid Carcinoma Who Appeared to Be Free of Disease After Total Thyroidectomy and Radioactive Iodine Ablation

In the presence of anti-thyroglobulin antibodies (TgAb), serum thyroglobulin (Tg) might be underestimated. Therefore, the American Thyroid Association does not recommend serum Tg after thyroid hormone withdrawal or recombinant human thyrotropin administration (stimulated Tg) and diagnostic whole-body scanning (DxWBS) in TgAb-positive patients who have serum Tg values while on thyroxine (Tg-on-T4) of <1 ng/mL. The objective of this study was to determine, in patients with differentiated thyroid cancer (DTC) who appeared to be free of disease after surgery and ablative treatment, but who had positive serum TgAb, the value of performing DxWBS and obtaining serum Tg under stimulated Tg conditions. There were 121 women and 15 men in the study. By selection criteria, all of them had total thyroidectomy with apparent complete tumor resection, remnant ablation with (131)I (1.1-5.5 GBq), and a post-(131)I therapy WBS that were negative for ectopic (131)I uptake. On assessment 8-12 months after (131)I ablation, their clinical exam needed to be normal, their Tg-on-T4 needed to be <1 ng/mL, and the test for TgAb needed to be positive. Stimulated Tg, neck ultrasound (US), and DxWBS were obtained from all patients. Patients with stimulated Tg >1 ng/mL without disease on US and DxWBS were evaluated by other imaging methods. In 10 (7.3%) patients, stimulated Tg was >1 ng/mL. The DxWBS revealed metastases in two of these patients, and other imaging methods showed disease in three others. Stimulated Tg was <1 ng/mL in 126 patients. DxWBS revealed metastases in three of these patients, and US detected lymph node metastases in four with a negative DxWBS. Tg stimulation combined with DxWBS revealed evidence for disease in 13 (9.5%) patients. When excluding patients with a positive US, DxWBS revealed metastases in four patients, and stimulated Tg of >1 ng/mL led to detection of persistent disease by other imaging methods in two more patients. Performing stimulated Tg and DxWBS at the same time seems to be useful after initial therapy in DTC patients with TgAb who do not otherwise appear to have persistent disease, even when US is negative.

Positron emission tomography/computed tomography in patients treated for differentiated thyroid carcinomas

Differentiated thyroid cancer (DTC) generally has a favorable prognosis; however, the chance of a recurrence in patients with DTC is 20%, and 8% of patients with recurrence will subsequently die of the disease. After thyroid remnant ablation, detectable serum thyroglobulin levels are a sensitive marker for residual or recurrent disease, while imaging procedures, primarily neck ultrasound and an iodine-131 (131I) or iodine-123 diagnostic whole-body scan, are useful to localize recurrent disease. However, ultrasound cannot identify lesions outside the neck, and diagnostic whole-body scan is of limited value if progressive dedifferentiation of thyroid carcinoma cells occurs. In these patients, fluorine-18 (18F)-fluorodeoxyglucose PET/computed tomography (18FDG-PET/CT) has been shown to improve detection and localization of tumor foci. Additionally, 18FDG-PET/CT is also of value in selecting patients unlikely to benefit from additional 131I therapy and those at highest risk of disease-specific mortality, which may prompt more alternative therapies. Recently, iodine-124 (124I)-PET/CT was proved to perform better than low-dose diagnostic 131I scans. Additionally, 124I PET/CT succesfully predicts the results of subsequent high-dose post-treatment 131I scans and allows lesion-based dosimetric calculations. The present article reviews the utility and limitations of PET/CT techniques in DTC management and offers practical recommendations.

Radioiodine remnant ablation in differentiated thyroid cancer after combined endogenous and exogenous TSH stimulation

Radioiodine remnant ablation (RRA) after (near-)total thyroidectomy (TE) is a key element in patients with differentiated thyroid cancer (DTC). The use of exogenous TSH stimulation (rhTSH) prior to RRA has shown promising results as compared to conventional thyroid hormone withdrawal (THW). As yet, the efficacy of RRA after brief THW and single rhTSH administration has not been assessed. The study sample comprised 147 patients with DTC referred to our center between May 2008 and September 2010. All patients received TE with subsequent RRA. None of these 147 patients had evidence of distant metastasis. 93 patients had endogenous TSH stimulation 4-5 weeks after surgery (group I) and twenty-six received two rhTSH injections (group II). 28 patients were treated with a single rhTSH injection after a brief THW (group III). RRA-Efficacy was assessed three months after therapy by diagnostic whole-body scan and measurement of the tumour marker thyroglobulin (Tg) under TSH stimulation. Three categories of success were defined for remnant ablation. Based on the definition of successful remnant ablation no visible uptake and a Tg ≤ 2.0 ng/ml (category 1) was seen in 62/93 patients in group I, in 17/26 patients in group II (p = n.s.) and in 12/28 patients in group III (p < 0.05). Visible radioiodine uptake and a Tg ≤ 2.0 ng/ml (category 2) was seen in 16/28 patients of group III and thus significantly more frequent than in group I (28/93 patients) (p < 0.01). However, patients in group III (16/28 patients) and group II (8/26 patients) showed no significant difference in this category (p = n.s.). Visible radioiodine uptake and a Tg > 2.0 ng/ml (category 3) was found in 3/93 patients in group I and 1/26 patients in group II but in no patient in group III. The third strategy of remnant ablation using a single injection of rhTSH after a brief THW period resulted in a significant higher rate of patients with residual uptake in the thyroid bed and a Tg level below 2 ng/ml three months after remnant ablation in comparison to THW. However, the overall efficacy of the third protocol was not significantly different as compared to two rhTSH injections. Under the aspect of the supply shortage of rhTSH the combined endogenous and exogenous TSH stimulation may be an attractive alternative for remnant ablation in differentiated thyroid cancer.

Value of Repeat Stimulated Thyroglobulin Testing in Patients with Differentiated Thyroid Carcinoma Considered to Be Free of Disease in the First Year After Ablation

In patients with differentiated thyroid carcinoma considered to be free of the disease after initial therapy, the appropriate timing or necessity of subsequent stimulated thyroglobulin (Tg) testing is uncertain. The objective of this study was to determine the value of a repeat stimulated Tg in patients considered to be free of disease 6-12 months after thyroid ablation, and also who continued to have serum Tg <1 ng/mL while on thyrotropin suppressive doses of thyroxine (T4) (Tg/T4), negative anti-Tg antibodies (TgAb), and a normal clinical examination 5 years after their initial therapy. The study participants were 203 patients who had total thyroidectomy followed by ablation with (131)I, who were considered to be free of disease 6-12 months after ablation (stimulated Tg <2 ng/mL in the absence of TgAb and negative diagnostic whole-body scanning), who had no recurrence, and who continued to have serum Tg/T4 of <1 ng/mL, negative TgAb and a normal clinical examination 5 years after initial therapy. These patients were evaluated with repeat stimulated Tg testing after 4 weeks of T4 withdrawal. Repeat stimulated Tg values after 5 years were <2 ng/mL in 192 (94.6%) patients of whom 188 were <1 ng/mL. Subsequent follow-up after a mean of 102 months did not detect new cases of tumor recurrence in this subgroup. Eleven patients (5.4%) had stimulated Tg levels of >2 ng/mL. Neck ultrasonography (US) revealed metastases in three and other imaging methods detected metastases in five patients with negative US. In the other three patients, no metastases were detected initially or during follow-up. Gender, age, and tumor stage were not predictors of recurrence or elevated Tg upon repeat testing after 5 years. The present results favor repeating stimulated Tg 5 years after ablation in patients who were initially considered to be free of disease and who continued to have Tg/T4 values of <1 ng/mL and negative TgAb tests. A negative predictive value of 100% was obtained for patients who continued to have low stimulated Tg values.

Differentiated Thyroid Cancer in Two Patients with Resistance to Thyroid Hormone

Resistance to thyroid hormone (RTH) is a genetic disease characterized by a reduced responsiveness of the pituitary and peripheral target tissues to TH. We describe two patients with RTH in whom differentiated thyroid cancer was diagnosed. In both patients, RTH was unequivocally diagnosed and both underwent thyroidectomy for multinodular goiter. In Patient 1, histology showed a papillary thyroid carcinoma pT2. Because serum thyrotropin (TSH) levels were elevated even while the patient was taking 150 μg daily of levothyroxine (LT(4)), the patient was treated with (131)I 100 mCi for ablation of the thyroid remnant without discontinuing his LT(4) therapy. We obtained a clinically adequate response by administering LT(4) 175 μg/day (2.18 μg/kg), but the serum TSH was persistently elevated on this dose. The patient was considered "free of disease" after 8 years of follow-up. In Patient 2, histology revealed a papillary microcarcinoma (0.6 cm). Diagnostic whole-body scan was performed while the patient was taking 100 μg/day LT(4), a time that his serum TSH was 38 μU/mL. Only a small remnant was revealed, so (131)I remnant ablation was not performed. While taking LT(4) at a dose of 175 μg/day (3 μg/kg), the serum TSH was persistently high, serum TH levels were in the normal-high range, and he appeared to be clinically euthyroid. There has been no evidence of persistent or recurrent thyroid carcinoma in ultrasonography and thyroglobulin measurements that have been performed on a yearly basis for 3 years. Patients with thyroid carcinoma and RTH are a unique model of thyroid cancer in which follow-up likely occurs in the setting of constantly elevated serum TSH concentrations. The concern in these patients is that their persistent elevation of serum TSH may have an adverse effect on their thyroid cancer, and management choices in terms of the dose of LT(4) that provides the optimum lowering of serum TSH without toxicity are difficult, particularly in the situation wherein, as was the case with one of our patients, there is cardiac disease.

Diagnostic 131I whole-body scintigraphy 1 year after thyroablative therapy in patients with differentiated thyroid cancer: correlation of results to the individual risk profile and long-term follow-up

(131)I whole-body scan (WBS) and serum thyroglobulin (TG) are important in detecting thyroid remnants or recurrent disease in patients with differentiated thyroid cancer. Usually, a diagnostic WBS is carried out 6 months after ablation to exclude residual disease. We retrospectively analysed results of a second routine diagnostic WBS and TG measurements at 1 year after thyroablation and correlated these to the risk profile of patients with long-term follow-up. A total of 197 patients were followed up after thyroidectomy and ablative (131)I therapy. Follow-up included clinical examination, radioiodine WBS and thyroid-stimulating hormone (TSH), free thyroxine and TG measurements at 3-6 months and 1 year after ablation. WBS (+) patients received a therapeutic activity of (131)I. The risk profile of patients was defined according to clinical results before the 1-year control. Clinical results at 1 year after ablation were analysed in correlation to the patient risk profile and long-term follow-up data (mean 7.2 years). One year after thyroablation, 95.8% of low-risk patients had no residual disease when diagnostic WBS was carried out using 370 MBq (131)I; 4.2% of low-risk patients had residual disease at this time point. In the high-risk group of this cohort, 54.5% were disease-free 1 year after ablation, but 45.5% demonstrated residual disease. After the 1-year control, 94% of all applied radioiodine therapies were executed in the high-risk group, compared with 6% in the low-risk group (p < 0.01). A second routine WBS 1 year after thyroablation is not indicated in low-risk patients. Risk stratification according to the early clinical course effectively identified patients with higher likelihood of persistent or recurrent disease in the long-term follow-up.

Thyroid Cancer Recurrence in Patients Clinically Free of Disease with Undetectable or Very Low Serum Thyroglobulin Values

This was a retrospective clinical study. The study was conducted at a university-based tertiary cancer hospital. One hundred seven patients had initial thyroid cancer surgery and subsequent remnant radioiodine ablation. Patients underwent recombinant human TSH (rhTSH)-mediated diagnostic whole-body scan and rhTSH-stimulated thyroglobulin (Tg) measurement before April 2001 if they had no antithyroglobulin antibodies, were clinically free of disease, and had one or more undetectable (≤0.5 ng/ml) or low (0.6-1 ng/ml) basal Tg measurements on levothyroxine. Patients were stratified according to their rhTSH-Tg responses: group 1, Tg 0.5 ng/ml or less (68 patients); group 2, Tg from 0.6 to 2.0 ng/ml (19 patients); and group 3, Tg greater than 2 ng/ml (20 patients). Tumor recurrence was measured. In group 1, two of 62 patients (3%) with follow-up recurred. In group 2, 63% converted to group 1, whereas two of 19 (11%) converted to group 3 and then recurred. Sixteen of the initial 20 group 3 patients (80%) recurred, including recurrence rates of 69 and 100% for those with an initial rhTSH-Tg greater than 2.0 ng/ml but 5.0 ng/ml or less, and 4.6 ng/ml or greater, respectively. One group 3 patient died of distant metastases. rhTSH-Tg more accurately predicted tumor recurrence than basal Tg. An rhTSH-Tg threshold of 2.5 ng/ml or greater optimally predicted future recurrence with sensitivity, specificity, and negative and positive predictive values of 80, 97, 95, and 84%, respectively. The prevalence of postablation thyroid cancer recurrence is predicted by the rhTSH-Tg response with an optimal Tg threshold of 2.5 ng/ml. Still, recurrent disease occurs in some patients with an initial rhTSH-Tg of 0.5 ng/ml or less.

Empiric High-Dose 131-Iodine Therapy Lacks Efficacy for Treated Papillary Thyroid Cancer Patients with Detectable Serum Thyroglobulin, but Negative Cervical Sonography and 18F-Fluorodeoxyglucose Positron Emission Tomography Scan

Some patients with elevated serum thyroglobulin (Tg) but a negative diagnostic whole body scan (WBS) after initial therapy for differentiated thyroid carcinoma may benefit from empirical radioactive iodine (RAI) therapy. However, previous studies enrolled patients with negative diagnostic WBS, regardless of neck ultrasonography (USG) and/or (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), which have become the preferred diagnostic procedures in such patients. The aim of this study was to evaluate the usefulness of empirical RAI therapy in patients with elevated stimulated Tg level and negative USG/FDG-PET findings after initial therapy for papillary thyroid carcinoma (PTC). This comparative study enrolled 39 patients with elevated stimulated Tg, negative diagnostic WBS, and negative USG/FDG-PET 1 yr after initial treatment. Empirical RAI therapy was performed in 14 patients (treatment group), whereas 25 patients were followed up without therapy (control group). There was no significant between-group difference in basal clinicopathological parameters. None of the 14 patients in the treatment group showed iodine uptake on posttreatment WBS. Five of 14 patients (36%) in the treatment group and eight of 25 (32%) in the control group had recurrence during the median 37 months of follow-up (P = 0.99). Changes in serum stimulated Tg concentrations did not differ between the two groups. Empirical RAI therapy and posttreatment WBS were not useful diagnostically or therapeutically in patients with positive serum stimulated Tg if such patients had negative USG and negative FDG-PET findings after initial treatment of PTC.