Are posttherapy radioiodine scans informative and do they influence subsequent therapy of patients with differentiated thyroid cancer?

Response to Surgery Assessments for Sparing Radioiodine Remnant Ablation in Intermediate-risk Papillary Thyroid Cancer

CONTEXT

Using response to surgery upon tailoring radioiodine (RAI) therapy for papillary thyroid cancer (PTC) is valued while lacking prospective validation.

OBJECTIVE

To spare RAI thyroid-remnant ablation among intermediate-risk PTCs by three-tiered assessments with response to surgery highlighted besides the risk of the recurrence stratification and TNM staging.

DESIGN, SETTING AND PARTICIPANTS

Patients with no evidence of disease (NED) identified as excellent response (ER) or indeterminate response (IDR) to surgery were spared from RAI thyroid-remnant ablation after informed consent and prospectively enrolled under active surveillance. Those involved in other trials or without sufficient follow-up data were excluded. Dynamic responses were followed and compared longitudinally.

MAIN OUTCOME MEASURES

NED presenting as durable ER or IDR for over 12 months.

RESULTS

Of the enrolled 215 patients, 47.4% (102/215) ER and 52.6% (113/215) IDR were identified upon RAI decision-making. After a median of 23.6 (IQR 13.8-31.6) months, the share of ER increased to 82.8%(178/215) and IDR decreased to 16.3% (35/215), with 85 patients shifting from IDR to ER over time, only 0.5% (1/215) structural and 0.5% (1/215) biochemical incomplete response observed. Successful remnant ablation was observed in 27.7%(26/94) of the patients completing two diagnostic whole-body scannings after a median interval of 13.0 months, indicating a theranostic effect. In the 173 patients followed for over 12 months, the NED rate didn't differ between ER and IDR subgroups (100% vs. 97.9%, P = 0.20).

CONCLUSIONS

Through the three-tiered assessments with response to surgery highlighted, postoperative ER and IDR spared from RAI remnant ablation may indicate similar favorable responses in intermediate-risk PTC patients during 23.6 months follow-up.

Molecular basis and targeted therapies for radioiodine refractory thyroid cancer

Patients diagnosed with radioiodine refractory thyroid cancer (RAIR-TC) are not amenable to novel ¹³¹ I therapy due to the reduced expression of sodium iodide symporter (Na+/I- symporter, NIS) and/or the impairment of NIS trafficking to the plasma membrane. RAIR-TC patients have a relatively poor prognosis with a mean life expectancy of 3-5 years, contributing to the majority of TC-associated mortality. Identifying RAIR-TC patients and selecting proper treatment strategies remain challenging for clinicians. In this review, we demonstrate the updated clinical scenarios or the so-called "definitions" of RAIR-TC suggested by several associations based on ¹³¹ I uptake ability and tumor response post-¹³¹ I therapy. We also discuss current knowledge of the molecular alterations involved in membrane-localized NIS loss, which provides a preclinical basis for the development of targeted therapies, in particular, tyrosine kinase inhibitors (TKIs), redifferentiation approaches, and immune checkpoint inhibitors.

Imaging of Treated Thyroid and Parathyroid Disease

The thyroid and parathyroid glands are endocrine structures located in the visceral space of the infrahyoid neck. Imaging plays a critical role in the evaluation of patients with thyroid cancer, both in the pre and posttreatment setting. Disorders of thyroid function, that is, hyperthyroidism and hypothyroidism, are also fairly common, although imaging utilization is less frequent with these conditions. Parathyroid dysfunction results in disordered calcium metabolism. Imaging is frequently applied in the preoperative assessment of these patients undergoing parathyroidectomy; however, routine imaging in the postoperative setting is uncommon. Parathyroid carcinoma is rare; however, imaging may be used in the pre and posttreatment setting.

A Joint Statement from the American Thyroid Association, the European Association of Nuclear Medicine, the European Thyroid Association, the Society of Nuclear Medicine and Molecular Imaging on Current Diagnostic and Theranostic Approaches in the Management of Thyroid Cancer

Background: The American Thyroid Association (ATA), the European Association of Nuclear Medicine, the European Thyroid Association, and the Society of Nuclear Medicine and Molecular Imaging have established an intersocietal working group to address the current controversies and evolving concepts in thyroid cancer management and therapy. The working group annually identifies topics that may significantly impact clinical practice and publishes expert opinion articles reflecting intersocietal collaboration, consensus, and suggestions for further research to address these important management issues. Summary: In 2019, the intersocietal working group identified the following topics for review and interdisciplinary discussion: (i) perioperative risk stratification, (ii) the role of diagnostic radioactive iodine (RAI) imaging in initial staging, and (iii) indicators of response to RAI therapy. Conclusions: The intersocietal working group agreed that (i) initial patient management decisions should be guided by perioperative risk stratification that should include the eighth edition American Joint Committee on Cancer staging system to predict disease specific mortality, the modified 2009 ATA risk stratification system to estimate structural disease recurrence, with judicious incorporation of molecular theranostics to further refine management recommendations; (ii) diagnostic RAI scanning in ATA intermediate risk patients should be utilized selectively rather than being considered mandatory or not necessary for all patients in this category; and (iii) a consistent semiquantitative reporting system should be used for response evaluations after RAI therapy until a reproducible and clinically practical quantitative system is validated.

Reappraising the Diagnostic Accuracy of Post-Treatment Whole-Body Scans for Differentiated Thyroid Carcinoma

Initial treatment for differentiated thyroid carcinoma (DTC) often consists of surgery and the administration of radioiodine. In this context, post-treatment Whole-Body Scans (ptWBS) are currently recommended, but data on its diagnostic accuracy are rare. The aim of the study was to evaluate the performance of ptWBS for distant metastasis in DTC patients. We included DTC patients who received radioiodine and underwent ptWBS between 2009-2015. The medical data were independently reviewed by two specialists to evaluate the concordance of positive distant ptWBS uptake and distant metastasis documented by imaging exams (gold standard). We studied 268 DTC patients. The mean age was 46±16 years (82% women), and papillary thyroid carcinoma was diagnosed in 87% of the patients. The median tumor size was 2.7 cm, 40% had lymph node involvement, and 11% had distant metastasis. Twenty-eight patients (10%) had distant ptWBS uptake, and nine of them (32%) were false-positives. In addition, nine false-negative ptWBS uptakes were identified. The overall performance of ptWBS showed 68% sensitivity and 96% specificity with significantly different performance according to the American Thyroid Association (ATA) risk groups. While the ptWBS performance for ATA low-intermediate-risk showed 29% sensitivity, 97% specificity, and Kappa of 0.19, the ATA high-risk group ptWBS displayed high sensitivity (82%), specificity (100%), and good agreement (Kappa 0.74). ptWBS is useful for a subgroup of ATA high-risk DTC patients. The overall poor performance of ptWBS suggests that it should be reconsidered for routine use in ATA at low to intermediate risk: the exam has little value to this subgroup.

Deep learning enables automated localization of the metastatic lymph node for thyroid cancer on 131I post-ablation whole-body planar scans

The accurate detection of radioactive iodine-avid lymph node (LN) metastasis on 131I post-ablation whole-body planar scans (RxWBSs) is important in tracking the progression of the metastatic lymph nodes (mLNs) of patients with papillary thyroid cancer (PTC). However, severe noise artifacts and the indiscernible location of the mLN from adjacent tissues with similar gray-scale values make clinical decisions extremely challenging. This study aims (i) to develop a multilayer fully connected deep network (MFDN) for the automatic recognition of mLNs from thyroid remnant tissue by utilizing the dataset of RxWBSs and (ii) to evaluate its diagnostic performance using post-ablation single-photon emission computed tomography. Image patches focused on the mLN and remnant tissues along with their variations of probability of pixel positions were fed as inputs to the network. With this efficient automatic approach, we achieved a high F1-score and outperformed the physician score (P < 0.001) in detecting mLNs. Competitive segmentation networks on RxWBS displayed moderate performance for the mLN but remained robust for the remnant tissue. Our results demonstrated that the generalization performance with the multiple layers by replicating signal transmission overcome the constraint of local minimum optimization, it can be suitable to localize the unstable location of mLN region on RxWBS and therefore MFDN can be useful in clinical decision-making to track mLN progression for PTC.

I-131 Postablation SPECT/CT Predicts Relapse of Papillary Thyroid Carcinoma more Accurately than Whole Body Scan

BACKGROUND/AIM

The aim of the study was to prospectively compare I-131 postablation Whole Body scan (WBS) and Single Photon Emission Computerized Tomography/Computerized Tomography (SPECT/CT) scan on thyroid cancer patients.

PATIENTS AND METHODS

Overall, 58 patients with papillary thyroid carcinoma were submitted to total thyroidectomy and I-131 remnant ablation. Post-ablation WBS and SPECT/CT scans performed on the same day were compared. Results of SPECT/CT were confirmed by neck and upper mediastinum ultrasound scan and on specific cases by a fully diagnostic CT scan, other tests and definitive histology acting as the gold standard. A total of 36/58 patients were followed-up for 5 years to detect relapse.

RESULTS

Mac Nemar Chi square and Fisher's exact tests disclosed statistically significant differences between WBS and SPECT/CT scan, concerning cervical lymphadenopathy detection (p=0.031) and relapse prediction by NM stage (p=0.033), respectively; SPECT/CT was more accurate in both comparisons.

CONCLUSION

In papillary thyroid carcinoma I-131 post-ablation SPECT/CT scan detects cervical lymphadenopathy and predicts relapse by NM stage more accurately than WBS.

Controversies, Consensus, and Collaboration in the Use of 131I Therapy in Differentiated Thyroid Cancer: A Joint Statement from the American Thyroid Association, the European Association of Nuclear Medicine, the Society of Nuclear Medicine and Molecular Imaging, and the European Thyroid Association

BACKGROUND

Publication of the 2015 American Thyroid Association (ATA) management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer was met with disagreement by the extended nuclear medicine community with regard to some of the recommendations related to the diagnostic and therapeutic use of radioiodine (¹³¹I). Because of these concerns, the European Association of Nuclear Medicine and the Society of Nuclear Medicine and Molecular Imaging declined to endorse the ATA guidelines. As a result of these differences in opinion, patients and clinicians risk receiving conflicting advice with regard to several key thyroid cancer management issues.

SUMMARY

To address some of the differences in opinion and controversies associated with the therapeutic uses of ¹³¹I in differentiated thyroid cancer constructively, the ATA, the European Association of Nuclear Medicine, the Society of Nuclear Medicine and Molecular Imaging, and the European Thyroid Association each sent senior leadership and subject-matter experts to a two-day interactive meeting. The goals of this first meeting were to (i) formalize the dialogue and activities between the four societies; (ii) discuss indications for ¹³¹I adjuvant treatment; (iii) define the optimal prescribed activity of ¹³¹I for adjuvant treatment; and (iv) clarify the definition and classification of ¹³¹I-refractory thyroid cancer.

CONCLUSION

By fostering an open, productive, and evidence-based discussion, the Martinique meeting restored trust, confidence, and a sense of collegiality between individuals and organizations that are committed to optimal thyroid disease management. The result of this first meeting is a set of nine principles (The Martinique Principles) that (i) describe a commitment to proactive, purposeful, and inclusive interdisciplinary cooperation; (ii) define the goals of ¹³¹I therapy as remnant ablation, adjuvant treatment, or treatment of known disease; (iii) describe the importance of evaluating postoperative disease status and multiple other factors beyond clinicopathologic staging in ¹³¹I therapy decision making; (iv) recognize that the optimal administered activity of ¹³¹I adjuvant treatment cannot be definitely determined from the published literature; and (v) acknowledge that current definitions of ¹³¹I-refractory disease are suboptimal and do not represent definitive criteria to mandate whether ¹³¹I therapy should be recommended.

Comparison of post-therapeutic sequential 131I whole-body scans in the detection of metastatic thyroid cancer

BACKGROUND

The aim was to compare the detect ability of three sequential 131I whole-body scans (tri-WBS) on the second, third, and fourth day after 131I therapy for metastatic thyroid cancer.

METHODS

Differentiated thyroid cancer patients who received oral high-dose 131I therapy underwent routinely tri-WBS on the second, third, and fourth day after total or near-total thyroidectomy in Zhongshan Hospital, Fudan University. We enrolled 137 patients with 261 tri-WBSs in this study between January 2015 and November 2017. The inclusion criteria was that at least one metastasis was found in the tri-WBS. We classified radioactive uptake of metastatic lesions by visual assessment into three grades: grade 0 = no uptake, grade 1= suspicious uptake, and grade 2 = definite uptake. The fourth day 131I WBS images were also compared with concurrent pre-therapeutic 99mTc-pertechnetate WBS images when available. We also analyzed the serum Tg levels of probably statistical difference in the patients with only lymph node, lung, bone, and multiple metastases when they underwent the first radioiodine ablation.

RESULTS

A total of 722 metastatic accumulations were identified in the final decisions, including 293 lymph node metastases, 261 nodular pulmonary metastases, 49 diffuse bilateral pulmonary metastases, 106 bone metastases, and 13 other metastases. The differences of intensity of uptake in sequential three day images were significant in visualization of lymph node metastasis (χ2=124.432, P<0.001), nodular pulmonary metastasis (χ2=160.334, P<0.001), diffuse bilateral pulmonary metastasis (χ2=41.710, P<0.001), and bone metastasis (χ2=22.118, P<0.001) in our study. Compared to the second day scans, the fourth day scans detected 87 (29.70%) more metastatic lymph nodes, 111 (42.53%) more nodular pulmonary metastases, 26 (53.06%) more diffuse bilateral pulmonary metastases and 17 (16.95%) more bone metastases. The differences of intensity of uptake between 99mTc-pertechnetate WBS and the fourth day 131I WBS were significant in visualization of lymph node metastasis (χ2=172.624, P<0.001), nodular pulmonary metastasis (χ2=111.004, P<0.001), diffuse bilateral pulmonary metastasis (χ2=17.400, P<0.001) and bone metastasis (χ2=46.298, P<0.001). The means of RTg in the patients with only lymph node, lung, bone metastasis, and multiple metastases were 47.20, 76.58, 89.00, and 91.56, respectively. The differences of serum Tg levels in the patients with only lymph node, lung, bone metastasis, and multiple metastases were significant (χ2=35.850, P<0.001).

CONCLUSIONS

The detect ability of tri-WBS was significantly different even for consecutive three-day images on the second, third, and fourth day after 131I therapy for metastatic thyroid cancer. There was a linear trend of increasing 131I uptake from the second to fourth day 131I WBS. The pre-therapy 99mTc-pertechnetate WBS demonstrated a poor ability to detect metastatic thyroid cancer compared to 131I WBS. There was an increasing trend of the means of RTg in patients with more extensive metastases.

Rare Clinical Entity: Metastatic malignant struma ovarii diagnosed during pregnancy - Lessons for management

Background

Malignant struma ovarii is an ovarian teratoma containing at least 50% thyroid tissue which has the potential to metastasize and produce thyroid hormone. Given its rarity, management strategies are not well-established. We report a case of metastatic malignant struma ovarii discovered during pregnancy with lessons for evaluation and management.

Case presentation

A 30-year-old woman who was two months pregnant was discovered to have struma ovarii with over half of the struma comprised of papillary thyroid cancer. Following tumor resection, delivery, and thyroidectomy, she underwent evaluation with stimulated thyroglobulin testing and diagnostic staging sodium iodide-131 scan (I-131), which revealed the presence of skeletal metastases. Following administration of 320 mCi I-131, post-therapy scan also showed miliary pulmonary metastases with improved ability to localize the bony and pulmonary metastases with concurrent SPECT/CT imaging. A second dosimetry-guided I-131 therapy resulted in complete resolution of pulmonary metastases; however, small foci of residual bone disease persisted. Post-therapy scans demonstrated additional findings not shown on diagnostic I-131 scans obtained prior to both her initial and second I-131 therapy.

Conclusions

SPECT/CT provides accurate anatomic correlation and localization of metastatic foci and can serve as a baseline study to assess interval response to treatment. Post-therapy scans should always be obtained when I-131 treatment is administered, as additional findings may be revealed versus low dose I-131 activity diagnostic scans. This patient had a high metastatic burden that would not have been discovered in a timely fashion with the conservative approach advocated by others. Thyroidectomy followed by a diagnostic staging radioiodine scan and a stimulated thyroglobulin level should be considered in patients with malignant struma ovarii for guiding therapeutic I-131 administration as metastatic risk is difficult to predict based on histopathologic examination.

Selected Controversies of Radioiodine Imaging and Therapy in Differentiated Thyroid Cancer

This article discusses the more controversial areas of the management of differentiated thyroid cancer, namely, the utility of pretherapy staging radioiodine scans; the prescribed activity for iodine-131 remnant ablation, adjuvant treatment, and distant metastases; preparation with thyroid hormone withdrawal versus recombinant human thyroid-stimulating hormone; and the classification of radioiodine refractory differentiated thyroid cancer. The author reviews various aspects of the controversies, such as the recommendations of the 2015 guidelines of the American Thyroid Association, arguments for and against the various controversies, and selected references.

Is postablation whole-body 131 I scintigraphy still necessary in intermediate-risk papillary thyroid cancer patients with pre-ablation stimulated thyroglobulin <1 ng/mL?

OBJECTIVE

Postablation whole-body scintigraphy, which is performed 5-7 days after administration of ablation activity of radioactive iodine-131 (¹³¹ I) in patients with thyroid cancer, is considered a routine procedure for remnant ablation and a useful tool for disease staging. However, the relationship of pre-ablation stimulated thyroglobulin (s-Tg) levels with postablation scintigraphic findings has not been evaluated. The current study was designed to determine the diagnostic value of postablation ¹³¹ I scintigraphy during initial staging and risk stratification in intermediate-risk papillary thyroid cancer (PTC) patients with pre-ablation s-Tg < 1 ng/ml at the time of ablation.

DESIGN

From January 2013 to July 2015, consecutive PTC patients at intermediate-risk of recurrence according to American Thyroid Association criteria were prospectively recruited. Patients had to have pre-ablation s-Tg < 1 ng/ml in the absence of anti-Tg antibody at the time of ablation. Systematic pre-ablation neck ultrasonography was performed for each patient. Postablation whole-body planar scintigraphy was obtained 5 days after administration of ablation activity of ¹³¹ I. Single photon emission computed tomography/low-dose computed tomography was added for patients whose planar findings were inconclusive.

RESULTS

Among 756 patients ablated, 240 (31·7%) patients were eligible for the analysis. Pre-ablation neck ultrasonography revealed lymph node metastases in eight of the 240 patients. Postablation scintigraphy showed ectopic neck uptake corresponding to the lymph nodes seen by ultrasonography in four patients and revealed neck lymph node metastases in another two patients whose ultrasonography findings were negative. None of the 240 patients showed distant metastasis on postablation scintigraphy. Neither staging nor initial risk stratification was altered by postablation scintigraphy in the included patients with pre-ablation s-Tg < 1 ng/ml.

CONCLUSIONS

As postablation whole-body scintigraphy played a minimal role in improving staging or initial risk stratification in intermediate-risk PTC patients with pre-ablation s-Tg < 1 ng/ml, we propose that postablation scintigraphy may be omitted in this group of patients. Multi-institutional larger studies are necessary to draw definitive conclusions.

Reappraisal of the indication for radioiodine thyroid ablation in differentiated thyroid cancer patients

Radioactive iodine therapy is administered to patients with differentiated thyroid cancer (DTC) for eradication of thyroid remnant after total thyroidectomy or, in patients with metastatic disease, for curative or palliative treatment. In past years, thyroid remnant ablation was indicated in almost every patient with a diagnosis of DTC. Nowadays, careful revision of patients' outcome has introduced the concept of risk-based selection of patients candidate to thyroid remnant ablation. The present review aims to underline the indications for thyroid remnant ablation and to address methodologies to be employed.

Current Guidelines for Postoperative Treatment and Follow-Up of Well-Differentiated Thyroid Cancer

Well-differentiated thyroid cancer is increasing in incidence but the disease-specific mortality remains very low. The only effective adjuvant treatment is radioactive iodine ablation. Guidelines regarding the use and dosage of radioactive iodine depend on pathologic features of the primary and metastatic tumor that define risk. Long-term treatment includes thyroid-stimulating hormone suppression and surveillance with serum thyroglobulin and radiologic assessment for nodal recurrence.

Novel Approaches to Thyroid Cancer Treatment and Response Assessment

The incidence of thyroid cancer has been increasing. After total thyroidectomy of well-differentiated thyroid tumors with intermediate- or high-risk features on pathology, radioiodine remains one of the mainstays of therapy for both thyroid remnant ablation as well as for treatment of metastatic disease. SPECT/CT, a relatively new modality, has been shown to play a pivotal role predominantly in the post-therapy setting by changing the risk stratification of patients with thyroid cancer. In the case of radioiodine treatment failure, FDG-PET/CT may provide prognostic information based on extent and intensity of metabolically active metastatic sites as well as serve as an important imaging test for response assessment in patients treated with chemotherapy, targeted therapies, or radiotherapy, thereby affecting patient management in multiple ways. The role of newer redifferentiation drugs has been evaluated with the use of I-124 PET/CT.

Recommendations for post-surgical thyroid ablation in differentiated thyroid cancer: a 2015 position statement of the Italian Society of Endocrinology

Post-surgical ablation of thyroid remnant with radioactive iodine (RAI) in differentiated thyroid cancer (DTC) is aimed to destroy any thyroid remnant in the thyroid bed (remnant ablation) and any microscopic foci of cancer cells eventually present within the thyroid remnant (adjuvant therapy). The present text is an attempt to offer practice guidelines for the indication of thyroid ablation and the preparation of DTC patients considering the latest achievement in the field and the changing epidemiology of DTC observed in the last 10 years.

METHODOLOGY

The executive committee of the Italian Society of Endocrinology appointed a task force of thyroid cancer expert including Nuclear Medicine Physicians and Endocrinologists to provide a consensus on the post-surgical ablation in thyroid cancer patients. The task force had no conflict of interest and had no commercial support. A number of specific topics were selected and the members selected relevant papers by searching in the Pubmed for articles published from 2000 to January 2015. Selected studies were categorized by level of evidence, and the recommendations were graded according to the level of evidence as high (A), moderate (B), or low (C).

2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the American Thyroid Association's (ATA's) guidelines for the management of these disorders were revised in 2009, significant scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid nodules and differentiated thyroid cancer.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles on adults were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations for therapeutic interventions. We developed a similarly formatted system to appraise the quality of such studies and resultant recommendations. The guideline panel had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid nodules include recommendations regarding initial evaluation, clinical and ultrasound criteria for fine-needle aspiration biopsy, interpretation of fine-needle aspiration biopsy results, use of molecular markers, and management of benign thyroid nodules. Recommendations regarding the initial management of thyroid cancer include those relating to screening for thyroid cancer, staging and risk assessment, surgical management, radioiodine remnant ablation and therapy, and thyrotropin suppression therapy using levothyroxine. Recommendations related to long-term management of differentiated thyroid cancer include those related to surveillance for recurrent disease using imaging and serum thyroglobulin, thyroid hormone therapy, management of recurrent and metastatic disease, consideration for clinical trials and targeted therapy, as well as directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid nodules and differentiated thyroid cancer. They represent, in our opinion, contemporary optimal care for patients with these disorders.

Clinical significance of diffuse hepatic uptake on post-therapeutic early and delayed (131)I scan in differentiated thyroid cancer: a preliminary report

OBJECTIVE

The purpose of this study was to investigate the clinical significance of diffuse hepatic uptake on post-therapeutic early and delayed (131)I scan in patients with differentiated thyroid cancer (DTC).

METHODS

We retrospectively analyzed 219 DTC patients who underwent high-dose (131)I treatment and subsequent post-therapeutic dual (131)I scan. Both early (third day after (131)I treatment) and delayed (5-6th day after (131)I treatment) (131)I scan images were visually assessed and diffuse hepatic uptake was scored using a 4-point grading system depending on intensity.

RESULTS

On early (131)I scan, 73 patients (33.4 %) showed diffuse hepatic uptake, while 191 patients (87.2 %) patients showed diffuse hepatic uptake on delayed scan (p < 0.0001). The serum levels of ALT in patients with diffuse hepatic uptake on early scan were higher than those without diffuse hepatic uptake on early scan (p = 0.03 for ALT and p = 0.08 for AST). The serum levels of ALT and AST trended with the grade of hepatic uptake on delayed scan (p = 0.03 for ALT and p = 0.05 for AST). Diffuse hepatic uptake on early or delayed scan showed no significant relationship in the presence of thyroid remnants, metastatic DTC lesions, tumor recurrence during follow-up, and the serum thyroglobulin level (p > 0.05). On logistic regression analysis, both serum ALT (p = 0.01) and AST (p = 0.04) levels were significant predictive factors for diffuse hepatic uptake on early scan, while only serum ALT (p = 0.01) level was significant predictive factor for diffuse hepatic uptake on delayed scan.

CONCLUSIONS

The frequency of diffuse hepatic uptake on the delayed scan was significantly higher than the early scan. Diffuse hepatic uptake on early post-therapeutic scan and the intensity of diffuse hepatic uptake on delayed scan showed significant correlation with the serum levels of hepatic enzymes, but no significant association in the presence of thyroid remnants, metastatic DTC lesions, and tumor recurrence during follow-up. The timing and intensity of diffuse hepatic uptake on post-therapeutic scan may be related with factors such as hepatic function other than the thyroid tissue or DTC.

Do negative 124I pretherapy positron emission tomography scans in patients with elevated serum thyroglobulin levels predict negative 131I posttherapy scans?

BACKGROUND

The management of patients with differentiated thyroid cancer (DTC) who have elevated serum thyroglobulin (Tg) levels and negative (131)I or (123)I scans is problematic, and the decision regarding whether or not to administer (131)I therapy (a "blind" therapy) is also problematic. While (124)I positron emission tomography (PET) imaging has been shown to detect more foci of residual thyroid tissue and/or metastases secondary to DTC than planar (131)I images, the utility of a negative (124)I PET scan in deciding whether or not to consider performing blind (131)I therapy is unknown. The objective of this study was to determine whether a negative (124)I pretherapy PET scan in patients with elevated serum Tg levels and negative (131)I or (123)I scans predicts a negative (131)I posttherapy scan.

METHODS

Several prospective studies have been performed to compare the radiopharmacokinetics of (124)I PET versus (131)I planar imaging in patients who 1) had histologically proven DTC, 2) were suspected to have metastatic DTC (e.g., elevated Tg, positive recent fine-needle aspiration cytology, suspicious enlarging mass), and 3) had (131)I planar and (124)I PET imaging performed. Using these criteria, we retrospectively identified patients who had an elevated Tg, a negative diagnostic (131)I/(123)I scan, a negative diagnostic (124)I PET scan, therapy with (131)I, a post-therapy (131)I scan, and a prior (131)I therapy with a subsequent positive post-(131)I therapy scan. For each scan, two readers categorized every focus of (131)I and (124)I uptake as positive for thyroid tissue/metastases or physiological.

RESULTS

Twelve patients met the above criteria. Ten of these 12 patients (83%) had positive foci on (131)I posttherapy scan.

CONCLUSION

In our selected patient population, (131)I posttherapy scans are frequently positive in patients with elevated serum Tg levels, a negative diagnostic (131)I or (123)I scan, and a negative (124)I PET scan. Thus, for a patient with elevated serum Tg level, negative diagnostic (131)I planar scan, and a prior post-(131)I therapy scan that was positive, a negative (124)I PET scan will have a low predictive value for a negative post-(131)I therapy scan and should not be used to exclude the option of blind (131)I therapy.

Clinical applications of SPECT/CT after first I-131 ablation in patients with differentiated thyroid cancer

OBJECTIVE

This study aimed to determine which thyroid cancer patients would benefit from SPECT/CT in addition to whole-body planar scintigraphy (RxWBS) for the detection and characterization of I-131 focal uptake after first ablation.

DESIGN AND PATIENTS

Neck and thoracic SPECT/CT was performed in 187 patients with I-131 focal uptake suggestive of remnant thyroid tissue (Rem group, n = 152) or presumed lymph node (LN) metastases (mLN group, n = 35) on RxWBS. Clinical and pathologic parameters were analysed and compared in patients with and without additional SPECT/CT findings.

RESULTS

wIn the Rem group, SPECT/CT revealed additional occult findings on RxWBS in 13 patients (8·6%). The serum thyroglobulin levels at the time of ablation were significantly higher in patients with additional SPECT/CT findings than in patients without additional findings (4·3 ± 3·4 ng/ml vs 1·6 ± 2·7 ng/ml, P = 0·001). In the mLN group, SPECT/CT demonstrated only remnant thyroid tissues without evidence of lymph node metastasis in 14 (40·0%) patients, whereas in the remaining 21 (60·0%) patients, I-131 uptake was confirmed in the corresponding neck and mediastinal lymph nodes on SPECT/CT.

CONCLUSIONS

Even in the Rem group, additional SPECT/CT could provide useful information for detecting hidden metastasis, especially in patients with high serum thyroglobulin levels. SPECT/CT should be recommended for patients with focal uptake lymph node metastasis on RxWBS.

Papillary thyroid cancer with bilateral adrenal metastases

BACKGROUND

Papillary thyroid cancer is the most common type of thyroid malignancy and has an excellent prognosis. Distant organ metastasis is rare. Bilateral adrenal metastases with iodine uptake has not been described before.

PATIENT FINDINGS

A 47-year-old woman presented for evaluation because of severe right upper arm pain and weakness. Magnetic resonance imaging of the thoracic spine showed a compression fracture at the third thoracic vertebra associated with a soft tissue mass. Computed tomography (CT)-guided biopsy of the mass showed metastatic papillary thyroid carcinoma. Ultrasonography of the neck showed an enlarged right thyroid lobe with cervical lymphadenopathy. A high-resolution CT scan of the chest showed multiple bilateral pulmonary nodules. Treatment included total thyroidectomy and lymph node dissection, external beam radiation to the thoracic spine, and (131)I therapy. Initial whole body (131)I scintigraphy showed faint uptake in the right upper abdomen, interpreted as a sign of physiologic bowel activity; however, repeat whole body (131)I scintigraphy showed increased uptake in both adrenal glands, consistent with metastatic disease. Serial abdominal CT scans showed progressively enlarging bilateral adrenal masses. Despite additional treatment with (131)I, the patient's disease progressed at all metastatic sites.

SUMMARY

This patient had bilateral adrenal metastases from advanced papillary thyroid cancer with distant metastasis to lung and bone at initial presentation and poor response to repeated (131)I therapy. Unilateral adrenal metastasis from thyroid cancer has been described previously in six cases; this is the first case report of bilateral adrenal metastases.

CONCLUSIONS

Bilateral adrenal metastasis is rare in papillary thyroid cancer. Elevated abdominal uptake of (131)I in a high-risk patient may be a sign of abdominal metastatic disease.

The role of nuclear medicine in differentiated thyroid cancer

In differentiated thyroid cancer (DTC) nuclear medicine is able to cover the spectrum from diagnosis and treatment to follow up keeping patient's management in one institution. Nowadays, DTC is often diagnosed per chance, presenting as small indolent nodule diagnosed on routinely performed ultrasound. Ultrasound and ultrasonography-guided fine-needle aspiration biopsy together with scintigraphy are probably the most adequate tools for diagnosis. After thyroidectomy, treatment with iodine-131 is routinely performed in a nuclear medicine therapy institution as a standard procedure in most of the cases with regard to histology. In case of iodine positive metastases, repeated therapies can be performed in order to reduce tumour burden. In the follow up of DTC thyroglobulin (tumour marker), ultrasound and diagnostic whole body scan are established procedures. With the development of SPECT/CT and PET/CT ((18)F-FDG, (68)Ga-somatostatin receptor) combining functional and anatomic imaging the nuclear medicine spectrum has further increased.

Imaging of the thyroid in benign and malignant disease

The thyroid gland was one of the first organs imaged in nuclear medicine, beginning in the 1940s. Thyroid scintigraphy is based on a specific phase or prelude to thyroid hormone synthesis, namely trapping of iodide or iodide analogues (ie, Tc99m pertechnetate), and in the case of radioactive iodine, eventual incorporation into thyroid hormone synthesis within the thyroid follicle. Moreover, thyroid scintigraphy is a reflection of the functional state of the gland, as well as the physiological state of any structure (ie, nodule) within the gland. Scintigraphy, therefore, provides information that anatomical imaging (ie, ultrasound, computed tomography [CT], magnetic resonance imaging) lacks. Thyroid scintigraphy plays an essential role in the management of patients with benign or malignant thyroid disease. In the former, the structure or architecture of the gland is best demonstrated by anatomical or cross-sectional imaging, such as ultrasound, CT, or even magnetic resonance imaging. The role of scintigraphy, however, is to display the functional state of the thyroid gland or that of a clinically palpable nodule within the gland. Such information is most useful in (1) patients with thyrotoxicosis, and (2) those patients whose thyroid nodules would not require tissue sampling if their nodules are hyperfunctioning. In neoplastic thyroid disease, thyroid scintigraphy is often standard of care for postthyroidectomy remnant evaluation and in subsequent thyroid cancer surveillance. Planar radioiodine imaging, in the form of the whole-body scan (WBS) and posttherapy scan (PTS), is a fundamental tool in differentiated thyroid cancer management. Continued controversy remains over the utility of WBS in a variety of patient risk groups and clinical scenarios. Proponents on both sides of the arguments compare WBS with PTS, thyroglobulin, and other imaging modalities with differing results. The paucity of large, randomized, prospective studies results in dependence on consensus expert opinion and retrospective analysis with inherent bias. With a growing trend not to ablate low-risk patients, so that a PTS cannot be performed, some thyroid carcinoma patients may never have radioiodine imaging. In routine clinical practice, however, imaging plays a critical role in patient management both before and after treatment. Moreover, as evidenced by the robust flow of publications concerning WBS and PTS, planar imaging of thyroid carcinoma remains a topic of great interest in this modern age of rapidly advancing cross sectional and hybrid imaging with single-photon emission computed tomography, single-photon emission computed tomography/CT, and positron emission tomography/CT.

Radioactive iodine therapy decreases recurrence in thyroid papillary microcarcinoma

Background. The most appropriate therapy for papillary microcarcinoma (PMC) is controversial. Methods. We reviewed the therapy and outcome of 407 patients with PMC. Results. Three hundred-eighty patients underwent total thyroidectomy, and 349 patients received I-131 therapy. The median followup was 5.3 years. Forty patients developed recurrent disease. On univariate analysis, development of disease recurrence was correlated with histological tumor size > 0.8 cm (P = 0.0104), age < 45 years (P = 0.043), and no I-131 therapy (P < 0.0001). On multivariate analysis, histological tumor size > 0.8 cm, positive lymph nodes, and no I-131 therapy were significant. The 5-year RFS for patients treated with I-131 was 95.0% versus 78.6% (P < 0.0001) for patients not treated with I-131. Patients with lymph node metastasis who did not receive I-131 had a 5-year RFS of 42.9% versus 93.2% (P < 0.0001) for patients who received I-131. Conclusions. Recommend I-131 remnant ablation for patients with PMC, particularly patients with lymph node metastasis.

Retro-orbital metastasis from differentiated thyroid carcinoma in a radioiodine therapy-naïve patient: any lesson learned?

OBJECTIVE

To present the case of a radioiodine therapy-naïve thyroid cancer patient with postthyroidectomy diplopia.

CLINICAL PRESENTATION AND INTERVENTION

A 63-year-old male patient presented with goiter. Histology performed after thyroidectomy proved follicular thyroid cancer. Without (131)I therapy, diplopia occurred from metastasis to the right medial rectus muscle. Improvement followed after one therapy dose of (131)I.

CONCLUSION

Postoperative radioiodine was important in managing this patient with differentiated thyroid cancer. This case showed that retro-orbital metastasis should be considered as a differential diagnosis in a patient with thyroid cancer who presents with unilateral diplopia.

Double-phase (131)I whole body scan and (131)I SPECT-CT images in patients with differentiated thyroid cancer: their effectiveness for accurate identification

OBJECTIVE

This study aims to determine whether a (131)I double-phase whole body scan (WBS) and SPECT-CT images have added value over a single-phase WBS image in identifying benign and malignant lesions in patients with well-differentiated thyroid cancer (DTC) at their first radioactive iodine (RAI) treatment.

METHODS

This study included 42 DTC patients who underwent their first radioablation. Post-therapeutic WBS images were acquired after 3 days (early phase) and 7 days (delayed phase). Following early-phase WBS, SPECT-CT images were obtained. The images were reviewed independently of the clinical data by 2 board-certified observers with a 6-point scoring system (benign to malignant -3 to +3).

RESULTS

The double-phase WBS and SPECT-CT images showed 115 radioiodine-avid localizations (81 benign and 34 malignant accumulations). Confidence levels of benign accumulations were significantly higher with SPECT-CT (average score -2.40 ± 1.06) compared to those of the early-phase WBS (average score -1.39 ± 1.88) (p < 0.0001) and delayed-phase WBS images (average score -1.49 ± 1.19) (p < 0.0001). When the analysis was restricted to accumulations with a low confidence score in the early-phase WBS image, the confidence level of the delayed-phase WBS was higher compared to that of the early-phase WBS images (p = 0.0012). The confidence levels of malignant accumulations were significantly higher with SPECT-CT images (average score 2.37 ± 0.96) compared to the early-phase WBS (average score 1.44 ± 1.21) (p < 0.0001) and the delayed-phase WBS images (average score 1.50 ± 1.13) (p < 0.0001).

CONCLUSION

Post-therapeutic SPECT-CT image was superior to the early-phase WBS image in enhancing the confidence level and accurately localizing the lesions. The delayed-phase WBS image contributed to the accurate diagnosis of benign lesions with a low confidence level in the early-phase WBS image.

The comparison of (131)I whole-body scans on the third and tenth day after (131)I therapy in patients with well-differentiated thyroid cancer: preliminary report

OBJECTIVE

The purpose of the present study was to evaluate the clinical usefulness of the delayed post-therapeutic (131)I scan in patients with well-differentiated thyroid cancer by comparing the early scanned images with the delayed images.

METHODS

A total of 81 patients (female:male = 67:14; age 52 ± 13 years) with well-differentiated thyroid cancer who underwent scans the third and tenth day after (131)I treatment were included in this study. The therapeutic dose ranged from 3.7 GBq (100 mCi) to 7.4 GBq (200 mCi). The early and delayed scan images were visually analyzed and the thyroid remnant-to-background uptake ratio (RBR) and the lesion-to-background uptake ratio (LBR) of metastatic lesions were calculated.

RESULTS

Of the 81 patients, 5 lesions (2 lung lesions, 2 cervical lymph node lesions, and one thyroid remnant) in 4 patients (5%) were additionally found on the delayed scans, which were not identified on the early scans. Of 8 patients with high serum thyroglobulin (Tg) and negative finding on the early scan, the delayed scan identified additional lesions in 3 patients (38%). Visual analysis scores significantly decreased for both thyroid remnants and metastatic lesions on the delayed scan (p < 0.001 for all). Diffuse hepatic uptake was visualized in 86% of all patients on the delayed scan, while only 6% of the patients on the early scan (p < 0.001). The RBRs of both scans were compared in 59 patients, and the LBRs were compared in 8 patients with 23 lesions. The mean RBR and LBR on the delayed scan (8.0 ± 7.6 and 5.4 ± 5.2, respectively) were significantly lower than those on the early scan (12.0 ± 10.8 and 10.8 ± 7.6, respectively; p = 0.02 and p = 0.001, respectively).

CONCLUSIONS

The (131)I-avid lesions on the early scan were more easily detected by visual analysis and had higher uptake ratios than those on the delayed scan. However, for patients with high serum Tg and negative finding on the early scan, the delayed scan was helpful in identifying additional (131)I-avid lesions.

Imaging of the thyroid and parathyroid glands

Current multimodal imaging techniques offer practicing providers the adequate framework to plan and accomplish care for patients with thyroid and parathyroid disorders. Available imaging modalities include ultrasonography (US), nuclear scintigraphy, computed tomography (CT), and magnetic resonance imaging (MRI). US remains the most cost-effective and the safest approach for the initial evaluation of the thyroid gland. Parathyroid subtraction scintigraphy provides localization of pathologic parathyroid glands with the greatest sensitivity. Localizing imaging studies allow for surgical planning with minimal risk and morbidity to the patient. CT scan and MRI play an adjunctive role in the further characterization of neck pathology.

Standard and emerging therapies for metastatic differentiated thyroid cancer

Differentiated thyroid cancer accounts for >90% of cases of thyroid cancer, with most patients having an excellent prognosis. Distant metastases occur in 10%-15% of patients, decreasing the overall 10-year survival rate in this group to 40%. Radioactive iodine has been the mainstay of treatment for distant metastases, with good results when lesions retain the ability to take up iodine. For patients with metastatic disease resistant to radioactive iodine, treatment options are few and survival is poor. Chemotherapy and external beam radiotherapy have been used in these patients, but with disappointing results. In recent years, our understanding of the molecular pathways involved in thyroid cancer has increased and a number of molecular targets have been identified. These targets include the proto-oncogenes BRAF and RET, known to be common mutations in thyroid cancer; vascular endothelial growth factor receptor and platelet-derived growth factor receptor, associated with angiogenesis; and the sodium-iodide symporter, with the aim of restoring its expression and hence radioactive iodine uptake. There are now multiple trials of tyrosine kinase inhibitors, angiogenesis inhibitors, and other novel agents available to patients with metastatic thyroid cancer. This review discusses both traditional and novel treatments for metastatic differentiated thyroid cancer with a particular focus on emerging treatments for patients with radioactive iodine-refractory disease.

The benefits and risks of I-131 therapy in patients with well-differentiated thyroid cancer

BACKGROUND

I-131 has been used in the therapy of well-differentiated thyroid cancer for over 50 years. Although the benefits and risks of I-131 remain issues of controversy and research, our understanding of them continues to improve. This review presents an overview of the benefits of I-131 therapy for ablation, adjuvant treatment, and treatment of locoregional and/or metastasis of well-differentiated thyroid cancer and considers the risks of complications of I-131 therapy.

SUMMARY

The benefits of I-131 remnant ablation include: [1] facilitating the interpretation of subsequent serum thyroglobulin levels, [2] increasing the sensitivity of detection of locoregional and/or metastatic disease on subsequent follow-up radioactive iodine whole-body scans, [3] maximizing the therapeutic effect of subsequent treatments, and [4] allowing a postablation scan to help identify additional sites of disease that were not identified on the preablation scan or when a preablation scan was not performed. The potential benefits of I-131 adjuvant treatment include decreasing recurrence and disease-specific mortality for unknown microscopic, locoregional, and/or distant metastatic disease. The potential benefits of I-131 treatment of known locoregional and/or distant metastases are [1] decreasing recurrence, and [2] decreasing disease-specific mortality and/or palliation. The more significant risks and side effects involve organ systems including eye/nasolacrimal, salivary, pulmonary, gastrointestinal, hematopoietic, and gonads as well as secondary primary malignancies.

CONCLUSIONS

Although there are never-ending controversies regarding I-131 therapy in well-differentiated thyroid cancer, the benefits and risks are becoming better understood. This in turn helps the treating physician and patient in making decisions regarding therapy.

Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer

BACKGROUND

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the publication of the American Thyroid Association's guidelines for the management of these disorders was published in 2006, a large amount of new information has become available, prompting a revision of the guidelines.

METHODS

Relevant articles through December 2008 were reviewed by the task force and categorized by topic and level of evidence according to a modified schema used by the United States Preventative Services Task Force.

RESULTS

The revised guidelines for the management of thyroid nodules include recommendations regarding initial evaluation, clinical and ultrasound criteria for fine-needle aspiration biopsy, interpretation of fine-needle aspiration biopsy results, and management of benign thyroid nodules. Recommendations regarding the initial management of thyroid cancer include those relating to optimal surgical management, radioiodine remnant ablation, and suppression therapy using levothyroxine. Recommendations related to long-term management of differentiated thyroid cancer include those related to surveillance for recurrent disease using ultrasound and serum thyroglobulin as well as those related to management of recurrent and metastatic disease.

CONCLUSIONS

We created evidence-based recommendations in response to our appointment as an independent task force by the American Thyroid Association to assist in the clinical management of patients with thyroid nodules and differentiated thyroid cancer. They represent, in our opinion, contemporary optimal care for patients with these disorders.

Recommendations of the Latin American Thyroid Society on diagnosis and management of differentiated thyroid cancer

The aims of these recommendations were to develop clinical guidelines for evaluation and management of patients with differentiated thyroid cancer applicable to Latin American countries. The panel was composed by 13 members of the Latin American Thyroid Society (LATS) involved with research and management of thyroid cancer from different medical centers in Latin America. The recommendations were produced on the basis of the expert opinion of the panel with use of principles of Evidence-Based Medicine. Following a group meeting, a first draft based on evidences and the expert opinions of the panel was elaborated and, later, circulated among panel members, for further revision. After, this document was submitted to the LATS members, for commentaries and considerations, and, finally, revised and refined by the authors. The final recommendations presented in this paper represent the state of the art on management of differentiated thyroid cancer applied to all Latin American countries.

Posttherapeutic (131)I SPECT-CT offers high diagnostic accuracy when the findings on conventional planar imaging are inconclusive and allows a tailored patient treatment regimen

PURPOSE

The purpose of this prospective study was to determine the diagnostic impact and influence on patient treatment of posttherapeutic (131)I SPECT-CT when the findings on planar posttherapeutic whole-body scintigraphy (ptWBS) were inconclusive.

MATERIALS AND METHODS

A total of 53 SPECT-CT scans were performed in 41 patients with thyroid cancer after high-dose (131)I therapy (2.944 to 7.526 GBq (131)I) because of diagnostic uncertainty on ptWBS. Physiological uptake in the salivary glands, gastric mucosa, gut, nasal mucosa, urinary tract and liver were considered to be normal. Any other foci of increased (131)I uptake, except iodine uptake clearly located in the thyroid bed, were considered to be abnormal. The data were evaluated on a lesion and a patient basis.

RESULTS

Regarding neck lesions, SPECT-CT provided a diagnostic impact in 26/90 lesions (28.9%) and confirmed the diagnosis in 64/90 lesions (71.1%). On a patient basis, SPECT-CT changed N status in 12/33 patients (36.4%), provided a diagnostic impact in 21/33 patients (63.6%) and led to a treatment change in 8/33 patients (24.2%). Regarding lesions distant from the neck, SPECT-CT confirmed the diagnosis in 62/71 lesions (87.3%) and had a diagnostic impact in 9/71 lesions (12.7%). On a patient basis, SPECT-CT changed M status in 4/19 patients (21.1%), had a diagnostic impact in 14/19 patients (73.7%) and led to a treatment change in 2/19 patients (10.5%). Considering all patients, SPECT-CT led to a treatment change in 10/41 patients (24.4%).

CONCLUSION

Integrated SPECT-CT is a useful tool, especially in cases of diagnostic uncertainty and helps to individualize patient management.

Current role of radionuclide imaging in differentiated thyroid cancer

Nuclear medicine plays an integral role in the management of differentiated thyroid cancer. This editorial aims to provide a summary of the current role of radionuclide imaging, including whole body iodine scan and fluorodeoxyglucose (FDG)-positron emission tomography (PET), in the diagnostic work-up and follow-up of patients with thyroid cancer.

Adrenal metastasis from a primary papillary thyroid carcinoma

Distant metastases of a papillary thyroid carcinoma (PTC) is rare, and usually involves the lung or the bones. Adrenal metastasis of a PTC has been described only in three patients. We describe a 74-year-old woman with adrenal metastasis of a PTC, detected with a total body iodine scan and a PET-CT scan.

Management of patients with low-risk papillary thyroid carcinoma

OBJECTIVE

To define a rational, cost-effective, simple approach to managing most patients with papillary thyroid cancer (PTC) who are at low-risk of either cause-specific mortality or tumor recurrence.

METHODS

Taking advantage of the collective experience of a cohort of 2512 patients with PTC who had initial definitive treatment at the Mayo Clinic in Rochester, Minnesota, between 1940 and 2000, a 5-step approach to the management of low-risk PTC has been devised. This program is based on appropriate preoperative ultrasound localization of neck disease and potentially curative surgery consisting of near-total or total thyroidectomy, with appropriate neck nodal exploration and resection.

RESULTS

The emphasis of the present program is on the extent of initial surgery, where optimal care is ascribed to a near-total thyroidectomy with curative intent and appropriate neck nodal resection as predicated by appropriate preoperative ultrasonography evaluation of regional lymph nodes. Radioiodine remnant ablation (RRA) is not applicable to patients with PTC who are defined on the day of definitive initial surgery to be at low risk as defined by a metastasis, age, completeness of resection, invasion, and size (MACIS) score of less than 6.

CONCLUSION

The outlook for patients with low-risk PTC is very optimistic, with rates at 30 postoperative years of only 1% for cause-specific mortality and less than 15% for tumor recurrence at any site. The long-term results obtained by potentially curative bilateral resection, appropriate regional lymph nodal excision, and selective use of RRA are excellent. Realistically improving these acceptably low rates for cause-specific mortality and tumor recurrence may be difficult.

Predictive Value of the Preablation Serum Thyroglobulin Level After Thyroidectomy Is Combined With Postablation 131I Whole Body Scintigraphy for Successful Ablation in Patients With Differentiated Thyroid Carcinoma

OBJECTIVES

To investigate the clinical importance of the combined use of serum thyroglobulin (Tg) levels measured just before ablation (ablation-Tg) and postablation 131I whole body scintigraphy (WBS) patterns for predicting ablation success in patients with differentiated thyroid carcinoma who received total thyroidectomy and 131I ablation therapy.

METHODS

We retrospectively studied the early clinical outcomes for 81 differentiated thyroid carcinoma patients treated with total thyroidectomy and high-dose 131I ablation therapy between June 2001 and July 2004.

RESULTS

Ablation success was achieved in 42 (97.7%) of the 43 patients with uptake in the thyroid bed only and ablation-Tg levels less than 10 ng/mL, whereas successful ablation was achieved in 9 (75.0%) of the 12 patients with uptake in the thyroid bed only and ablation-Tg levels equal to or greater than 10 ng/mL (P = 0.029). Among 15 patients with uptake including a lymph node and ablation-Tg levels less than 10 ng/mL, 14 patients (93.3%) showed ablation success, whereas successful ablation was achieved in only 2 (18.2%) of the 11 patients with uptake including a lymph node and ablation-Tg levels equal to or greater than 10 ng/mL (P < 0.001).

CONCLUSIONS

These data indicate that the combined use of serum Tg levels measured just before ablation and the 131I WBS patterns after ablation may be an early predictor of ablation success in patients with differentiated thyroid carcinoma who received total thyroidectomy and high-dose 131I ablation therapy.