The comparative value of serum thyroglobulin measurements and iodine 131 total body scans in the follow-up study of patients with treated differentiated thyroid cancer

Efficacy of Empirical 131I Radioiodine Therapy in Well-Differentiated Thyroid Carcinoma Patients With Thyroglobulin-Elevated Negative Iodine Scintigraphy Syndrome: A Systematic Review and Meta-analysis

OBJECTIVES

This study aimed to perform a systematic review and meta-analysis on the efficacy of empirical high-dose radioiodine therapy in treating differentiated thyroid cancer patients with thyroglobulin (Tg)-elevated negative iodine scintigraphy (TENIS) syndrome.

METHODS

We searched PubMed, EMBASE, and the Cochrane Library to identify relevant studies published until April 2022. This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist and registered in an international prospective register of systematic reviews (PROSPERO). Meta-analyses of proportions and odds ratios were performed to assess the beneficial effect of empirical high-dose radioiodine therapy in patients with TENIS syndrome. Subgroup analysis was also performed according to the presence of micrometastasis or macrometastasis.

RESULTS

We identified 14 studies including 690 patients who received empirical high-dose radioiodine therapy for TENIS syndrome. Those who had micrometastasis exhibited additional lesions not previously observed on diagnostic whole-body scan (prop = 0.64, 95% confidence interval [CI], 0.51-0.77) and had reduced serum Tg levels (prop = 0.69; 95% CI, 0.52-0.84) after empirical radioiodine treatment. No such findings were observed among patients with macrometastasis. Moreover, we found that the empirical radioiodine treatment group had lower serum Tg levels than did controls (odds ratio = 0.27; 95% CI, 0.09-0.87), which suggests a lower risk of disease progression.

CONCLUSION

Our findings indicate that empirical high-dose radioiodine therapy promoted beneficial effects and could be recommended for patients with TENIS syndrome, especially those with micrometastasis.

Efficacy of Empirical Radioiodine Therapy in Patients with Differentiated Thyroid Cancer and Elevated Serum Thyroglobulin without Evidence of Structural Disease: A Propensity Score Analysis

We assessed the outcome of administration of empiric radioactive iodine (RAI) therapy to patients with differentiated thyroid cancer (DTC), in a propensity-score-matched cohort of patients with biochemical incomplete response (BIR) and without evidence of structural disease. We retrospectively evaluated 820 DTC patients without distant metastases, who underwent total thyroidectomy followed by RAI therapy, with available BIR at 12 months and follow-up evaluations. The patients were categorized according to the administration of empiric therapy (ET). To account for differences between patients with (n = 119) and without (n = 701) ET, a propensity-score-matched cohort of 119 ET and 119 no-ET patients was created. The need for additional therapy and the occurrence of structural disease were considered as end-points. During a median follow-up of 53 months (range 3-285), 57 events occurred (24% cumulative event rate). The rate of events was significantly higher in the no-ET compared to the ET patients (30% vs. 18% p < 0.001). The multivariate Cox analysis identified age (p < 0.01), pre-therapy Tg (p < 0.05) and empiric RAI therapy (p < 0.01) as predictors of outcome. The Kaplan-Meier analysis found that progression-free survival was lower in no-ET patients compared to the ET group (p < 0.01). In patients with DTC treated with surgery and RAI, and with biochemical incomplete response at the 12-month evaluation, their prognosis seemed to be affected by Tg values and the empiric treatment. The identification of candidates for this approach may improve prognosis.

Outcome of 18f-Fluorodeoxyglucose Positron Emission Tomography (PET)-Directed Resections in Differentiated Thyroid Carcinoma (DTC): Experience in a Developing Country

The aim of this study was to assess the accuracy of 18F-fluorodeoxyglucose positron emission tomography (18-FDG-PET scan) in localizing the disease in differentiated thyroid carcinoma patients undergoing re-operations. This is a retrospective analysis of a prospectively maintained data (December 2007 to December 2016). The patients included had elevated serum thyroglobulin (Tg) levels and negative iodine uptake (TENIS) and planned for re-operation with one or more accessible site of metastasis detected on FDG-PET scan. Clinical details, FDG-PET/CT findings, operative findings, histology, pre-, and post-operative Tg levels were recorded. Thirty-two patients were included. The mean age of the patients was 46.8 ± 15.8 years (M:F = 1:1.6) and mean pre-operative Tg value was 247.6 ± 92.3 ng/ml. FDG-PET disclosed a total of 77 hot spots in these 32 patients, 56 of which were surgically explored and resections performed. Patient- and lesion-based positive predictive value (PPV) of FDG-PET in detecting recurrent/metastatic DTC lesions was 87.5 and 71%, respectively. Remaining cases had granulomatous or nonspecific inflammatory lesions. A total of 12.5% of recurrent DTC patients explored could achieve biochemical cure. All these had disease confined to neck. Remaining patients continued to have high serum Tg level, though it fell substantially in majority of patients. False positive scans are frequent in regions with high prevalence of inflammatory diseases. Hence, FDG-PET directed re-operations should be taken up judiciously.

High thyroglobulin and negative whole-body scan: no long-term benefit of empiric radioiodine therapy

PURPOSE

Around 10-27% of patients will present elevated thyroglobulin (Tg) levels and negative diagnostic whole-body scan (dxWBS) during differentiated thyroid cancer (DTC) follow-up. Empiric radioactive iodine (RAI) therapy in this context is controversial due to the lack of good quality studies in the context. The main purpose of this study is to compare long-term response to therapy status and overall survival between empiric RAI treated and untreated DTC patients.

METHODS

A retrospective study comparing differentiated thyroid cancer patients with negative diagnostic whole-body scan and elevated thyroglobulin levels submitted or not to empiric radioactive iodine therapy in a thyroid cancer referral center. The main outcome measures were ATA Response to Therapy Stratification at 6-12 months after RAI ablative dose, at 6-18 months after negative dxWBS and last follow-up visits.

RESULTS

Overall, 120 DTC patients with stimulated Tg >10 ng/ml and negative dxWBS were included in this study. Overall, 53 patients were submitted to empiric RAI and 67 were in the control group. No difference was observed in ATA Response to Therapy Stratification after RAI ablation or at the end of follow-up between groups. Also, no difference was found in terms of Tg changes response. After more than 10 years of follow-up, 17 patients died (13 from treated and 4 from untreated group).

CONCLUSIONS

Empiric RAI treatment was not associated with better long-term ATA response to therapy status or overall survival.

Critical Aspects of Immunoradiometric Thyroglobulin Assays

Background and aim of the study

Thyroglobulin (Tg) evaluation is currently used in the follow-up of patients with differentiated thyroid carcinoma (DTC), but the measurement methods are flawed by analytical inaccuracy. In this paper we describe the results of a comparison between seven different immunoradiometric assays (IRMAs) for Tg determination.

Material and methods

Tg was measured in 50 patients with DTC by means of the following commercially available IRMA kits: HTGK-2 (DiaSorin), Tg IRMA (Schering-CIS bio international), ELSA-hTG (Schering-CIS bio international), Tg IRMA C.T. (ICN Pharmaceuticals), SELco Tg (Medipan Diagnostica), Tg Bridge IRMA (Adaltis) and IRMA-mat Tg (BYK-Sangtec Diagnostica). The distribution of the Tg values measured by the different IRMAs was compared and a correlation analysis was performed.

Results

The Tg values were widely dispersed and the classification of patients according to Tg concentrations of clinical relevance varied depending on the IRMA used.

Conclusion

Despite efforts to develop standardized Tg assays, the measurement of this biomarker is still affected by a considerable degree of analytical inaccuracy. Tg values vary widely between assays and the classification of patients according to Tg values with clinical relevance is still dependent on the assay used.

A rare case report of very low thyroglobulin and a negative whole-body scan in a patient with a solid variant of papillary thyroid carcinoma with distant metastases

RATIONALE

The early detection of recurrent differentiated thyroid carcinoma (DTC) cells in postsurgery DTC patients relies on the sensitivity of measuring both the level of thyroglobulin (Tg) and 131-iodine distribution on a whole-body scan (WBS). Recent studies have defined patients who subsequently have no evidence of disease as those who have a stimulated Tg level <1 ng/mL with no other radiological or clinical evidence of disease.

PATIENT CONCERNS

A woman patient with solid variant papillary thyroid carcinoma (SVPTC) had undergone twice thyroidectomy with lymph node dissection and radioactive therapy. Recently, she was found to have lung and brain metastases despite a very low serum Tg level and a negative WBS. Nowadays, the patients have suggested targeted treatment, such as tyrosine kinase inhibitors, may be worthy of consideration to prevent the related events.

DIAGNOSES

She was diagnosed as PTC.

INTERVENTIONS

She had undergone twice thyroidectomy with lymph node dissection and radioactive therapy.

OUTCOMES

She was found to have lung and brain metastases despite a very low serum Tg level and a negative WBS.

LESSONS

We aim to suggest that patients with SVPTC should be treated cautiously because they may have a higher frequency of distant metastases and a less favorable prognosis compared with patients with classical papillary thyroid cancer.

Value of post-therapeutic ¹³¹I scintigraphy in stimulated serum thyroglobulin-negative patients with metastatic differentiated thyroid carcinoma

Metastatic differentiated thyroid carcinoma (DTC) with positive (131)I scintigraphy, but negative stimulated Tg (sTg) is relatively rare in clinical practice. The clinical characteristics of these patients were analyzed in the current study. A total of 3367 consecutive histologically proven DTC patients were analyzed retrospectively from January 2007 to June 2013. Tg negativity was defined as a sTg level of <2 ng/mL without positive anti-Tg antibody (TgAb level of <100 IU/mL) under thyroid-stimulating hormone stimulation (TSH level of ≥30 mIU/L). Analyses were performed using the Statistical Package for the Social Sciences, version 20.0 (SPSS, Chicago, IL, USA). Seventy-one patients (median age 45 years, range 17-68 years) were post-therapeutic (131)I-SPECT/CT positive and sTg negative (PTP-TN) constituting 2.1 % of all patients. Of these 71 patients, 2 (2.8 %) had bone metastasis, 11 (15.5 %) had lung metastasis, and 59 (83.1 %) had lymph node metastasis. Fifty-six patients had cervical lymph node metastasis (cLNM), and US was positive in 15 patients (26.8 %), while negative in 41 patients (73.2 %). When compared to patients with concordant positive results for sTg and (131)I scintigraphy, US showed a relatively lower positive rate in the detection of cLNM in PTP-TN patients (28.8 vs. 53.8 %; χ (2) = 6.70; P = 0.01). In conclusion, even with sTg <2 ng/mL, there is a low risk of metastatic DTC. US had limitations in PTP-TN patients, while post-therapy (131)I-SPECT/CT demonstrated an advantage in the detection of functioning metastasis despite low sTg levels in patients with metastatic DTC.

Assessment of the Role of Different Imaging Modalities with Emphasis on Fdg Pet/Ct in the Management of Well Differentiated Thyroid Cancer (WDTC)

BACKGROUND

Positron emission tomography/computed tomography is suggested to have a role in detection of iodine negative recurrence in well differentiated thyroid cancer. The aim of this study is to identify role of different imaging modalities in the management of well differentiated thyroid cancer.

METHODS

We reviewed 900 well differentiated thyroid cancer patients after post-thyroidectomy who underwent recombinant human thyroid stimulating hormone stimulated Sodium Iodide I 131 imaging. Out of 900 patients, 74 had positron emission tomography/computed tomography. Multivariate analysis was performed by controlling positron emission tomography/computed tomography, Sodium Iodide I 131 scan, neck ultrasonography, age, sex, primary tumor size, stage, histology, thyroglobulin. Patients were grouped according to results of Sodium Iodide I 131 scan and positron emission tomography/computed tomography.

RESULTS

Positron emission tomography/computed tomography was positive in 23 of 74 patients. The sensitivity for positron emission tomography was 11/11(100%), the specificity was 51/63 (81.0%), the positive predictive value was 11/23 (47.8%), and the negative predictive value was 51/51 (100%). The sensitivity for the neck ultrasonography was 4/8 (50%), the specificity was 53/60 (88.3%), positive predictive value was 4/11 (36.4%), and negative predictive value was 53/57 (93.0%). 50% of patients who had Sodium Iodide I 131 negative scan and positive positron emission tomography/computed tomography had a change in management. Thirty-six percent with positive neck ultrasonography had a change in management. Out of 11 recurrences, 6 had distant metastatic disease, and 5/11 had regional nodal disease. Neck ultrasonography showed nodal metastasis in 4/5 (80%).

CONCLUSION

Positron emission tomography/computed tomography altered management in the presence of a high thyroglobulin level and a negative Sodium Iodide I 131 scan. Neck ultrasonography should be the first line of imaging with rising thyroglobulin levels. Positron emission tomography/computed tomography should be considered for cases with high thyroglobulin levels and normal neck ultrasonography to look for distant metastatic disease.

Practice trends in patients with persistent detectable thyroglobulin and negative diagnostic radioiodine whole body scans: a survey of American Thyroid Association members

BACKGROUND

Management of patients with thyroglobulin (Tg)-positive/scan-negative thyroid cancer remains challenging. American Thyroid Association (ATA) guidelines recommend potential use of empiric (131)I therapy and various scanning modalities, but no standard for managing such cases exists.

METHODS

We surveyed ATA members to assess current practice in management of patients with Tg-positive/scan-negative disease. Members participated in a web-based survey of six case scenarios of Tg elevations but iodine scan negativity.

RESULTS

A total of 288 ATA members (80% male) participated. Patient age, sex, and basal and stimulated Tg varied between the cases. Respondents were asked their opinion regarding empiric (131)I therapy use, including (131)I dose, use and duration of low-iodine diet, thyroxine withdrawal or recombinant human thyrotropin (rhTSH), and utilization of additional imaging (neck ultrasound (US) or positron emission tomography/computed tomography (PET/CT)) and reconsideration of (131)I therapy. Between 16% and 51% recommended initial use of empiric (131)I for the various scenarios. The majority chose a (131)I dose between 75 and 150 mCi, and 73% employed a low-iodine diet for two or more weeks. Preference between thyroxine withdrawal versus rhTSH was evenly split. More than 98% obtained a neck US if empiric (131)I was not given; 52-89% would proceed to PET/CT if US was negative. Only 44% used rhTSH stimulation in PET scan preparation. (131)I use was more common with stimulated Tg significantly >10 ng/mL. (131)I therapy was slightly more likely with PET-positive (56%) than PET-negative status (45%). Respondents were split regarding empiric (131)I if basal and stimulated Tg increased ≥150% over two years. Providers in North America less commonly utilized (131)I treatment than those from other areas. In the face of possible heterophilic antibody interference in the Tg assay, the majority did not recommend (131)I therapy.

CONCLUSIONS

Empiric (131)I therapy is still utilized for patients with Tg-positive/scan-negative disease. Neck US is frequently used to further evaluate such cases as (18)FDG-PET/CT, albeit the latter is used somewhat less often. Use of (131)I therapy correlated with the degree of Tg elevation or development of Tg antibodies, and was recommended more commonly with PET-positive than PET-negative status in patients with lower Tg levels. (131)I was less commonly used by providers within North America.

Diagnostic value of 18F-FDG PET/CT in patients with TENIS syndrome: correlation with thyroglobulin levels

OBJECTIVE

The aim of the study was to disclose the place of (18)F-FDG PET/CT to predict recurrent disease in patients with differentiated thyroid cancer (DTC), negative radioiodine whole-body scan (WBS) and high serum thyroglobulin (Tg).

METHODS

Seventy-one patients who underwent total thyroidectomy followed by radioactive iodine ablation and had negative radioiodine WBS but elevated Tg levels underwent PET/CT. They were followed up for 6-50 months (median 23) for the occurence of recurrent disease as detected by either clinical findings, other imaging modalities or histopathological examination. The place of PET/CT findings at baseline to predict the presence of recurrent disease was evaluated. Correlation between PET/CT findings and Tg levels was examined and a threshold for Tg level above which the predictive value of PET/CT was highest was determined.

RESULTS

PET/CT was positive for recurrent disease in 38 (53.5%) patients. The sensitivity, specificity, PPV, NPV and diagnostic accuracy of PET/CT to predict the occurence of recurrent disease at follow-up were 68.8, 78.3, 86.8, 54.5 and 71.9%, respectively. The sensitivity, accuracy and PPV of PET/CT increased with increasing Tg levels. The highest diagnostic accuracy of PET/CT, with a sensitivity of 76.2% and a specificity of 100% to detect recurrent disease appeared to be at a Tg level greater than 29 ng/mL.

CONCLUSION

Our findings suggest that (18)F-FDG-PET/CT is a valuable tool to predict the occurence of recurrent disease in patients with DTC, negative WBS and elevated Tg levels. PET/CT positivity has been shown to be strongly and positively correlated with Tg levels in this patient subset.

Sella turcica metastasis from follicular carcinoma of thyroid

A case of metastasis to the sella turcica from a follicular adenocarcinoma of the thyroid gland is presented. Metastasis to this site is rare and review of the literature reveals only 12 cases of metastatic thyroid carcinoma involving the sella turcica and pituitary gland. The optimal treatment strategy is still to be determined. A 43-year-old woman presented with headache, nausea, visual impairment and galactorrhea. An MRI scan of the cranium revealed an enhancing destructive sellar lesion. The patient underwent transsphenoidal removal of the lesion to alleviate visual loss. The histological features of the sellar tumor were identical to those of a follicular adenocarcinoma partially removed from the thyroid gland 22 months earlier. Total thyroidectomy followed by three courses of iodine-131 ablation enhanced with synthetic thyrotropin and thyroid hormone suppression therapy was instituted. The post-operative course was satisfactory with improved vision and ceased galactorrhea. This case was successfully treated with a combination of surgical removal, iodine-131 ablation and hormone suppression therapy, which resulted in disease control duration of four years. Sella turcica metastases of thyroid carcinoma are exceedingly rare and currently there are no established therapeutic guidelines.

Sustained and diffuse 131I avid bone metastases with low thyroglobulin levels in a patient with papillary thyroid carcinoma

A 63-year-old man with papillary thyroid carcinoma (PTC) and bone metastases was treated with 131I residual thyroid ablation (RTA) and 2 repeated post-ablation 131I therapies after total thyroidectomy. 131I whole-body scans (WBS) demonstrated sustained and diffuse 131I avid bone metastases, accompanied by persistent very low thyroglobulin (Tg) levels and negative antithyroglobulin antibody (TgAb) in post-ablation 131I therapies in hypothyroid state after levothyroxine withdrawal. The spread of bone metastases were found on the last therapeutical 131I WBS. The benefit of 131I therapy after levothyroxine withdrawal should be weighed even if the metastases are 131I avid in poorly differentiated thyroid carcinoma.

Thyroid carcinoma uptake of 18F-fluorodeoxyglucose in patients with elevated serum thyroglobulin and negative 131I scintigraphy

PURPOSE

To determine if FDG-PET results can predict for outcome in thyroid cancer patients with elevated Tg and negative I-131 imaging.

MATERIALS AND METHODS

We conducted a retrospective review of 76 patients who had elevated serum Tg and negative (131)I scintigraphy and who underwent FDG-PET. After FDG-PET, patients underwent neck dissection or radiation.

RESULTS

The 51 patients with positive FDG-PET had a 5-year survival of 63% compared to 100% (p<0.049) for the 25 patients with negative PET. Patients with FDG-avid disease isolated to the lymph nodes had 5-year CSS of 91% compared to 32% (p=0.0033) for those with disease outside the regional lymph nodes. Twenty-nine patients with disease isolated to the regional lymph nodes underwent salvage neck dissection and 22 remain NED after 28 months.

CONCLUSIONS

Negative FDG-PET with elevated Tg predicts an excellent outcome. FDG-avid disease isolated to the regional lymph nodes had a low likelihood of death due to thyroid cancer.

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

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

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

18F-fluorodeoxyglucose and 131I radioguided surgical management of thyroid cancer

OBJECTIVE

To describe a technique that assists in the surgical management of recurrent local regional well-differentiated thyroid cancer (WDTC).

STUDY DESIGN

Case series with chart review.

SETTING

Two academic health centers from 2001 to 2009.

SUBJECTS AND METHODS

Patients operated upon by the senior surgeon (BCS) for recurrent WDTC.

RESULTS

Thirteen patients with recurrent WDTC were operated upon with radioguided surgical (RGS) technique to indentify recurrence for excision. Eight patients had iodine avid disease and were candidates for RGS with (131)I. The remaining 5 patients had cancer with a proven loss of iodine avidity and were, therefore, operated upon with a fluorodeoxygluocose (FDG) RGS technique.

CONCLUSION

RGS is a feasible approach to identify recurrent disease in an operated field and ensure its successful excision. Although focal disease may be identified with this technique, this is not a tool for limited excisions ("berry picking").

Combined [18F]Fluorodeoxyglucose Positron Emission Tomography and Computed Tomography (FDG-PET/CT) for Detection of Recurrent, 131I-Negative Thyroid Cancer

BACKGROUND

Whole-body (131)I scintigraphy (WBS) and serial thyroglobulin measurement (Tg) are standard methods for detecting thyroid cancer recurrence after total/near total thyroidectomy and (131)I ablation. Some patients develop elevated Tg (Tg-positive) or there is clinical suspicion of recurrence, but WBS are negative (WBS-negative). This may reflect non-iodine-avid recurrence or metastasis. In 2002, the Centers for Medicare and Medicaid Services (CMS) approved positron emission tomography with [(18)F]fluorodeoxyglucose (FDG-PET) for Tg-positive/WBS-negative patients with follicular-cell-origin thyroid cancer. Limited data are available regarding the performance of combined FDG-PET/computed tomography (FDG-PET/CT) for detecting recurrent thyroid cancer in WBS-neg patients.

METHODS

This retrospective review of prospectively collected data analyzed 65 patients who had FDG-PET/CT for suspected thyroid cancer recurrence (April 1998-August 2006). Patients were WBS-negative but were suspected to have recurrence based on Tg levels or clinical grounds. Suspected FDG-PET/CT abnormalities were reported as benign or malignant. Lesions were ultimately declared benign or malignant by surgical pathology or clinical outcome (disease progression).

RESULTS

Of 65 patients who underwent FDG-PET/CT, 47 had positive FDG-PET/CT. Of the positive FDG-PET/CT, 43 studies were true positives, with 21 (49%) confirmed pathologically by surgical resection. The four false positives (3/4 confirmed pathologically) included an infundibular cyst, an inflamed supraclavicular cyst, pneumonitis, and degenerative disc disease. Of the 18 FDG-PET/CT studies that were negative, 17 were true negatives and one was a false negative (metastatic papillary carcinoma). Thus, FDG-PET/CT demonstrated a patient-based sensitivity of 98%, specificity of 81%, positive predictive value of 91%, and negative predictive value of 94%.

CONCLUSIONS

FDG-PET/CT is useful for detecting thyroid cancer recurrence in WBS-negative patients, and can assist decision making.

Contemporary Imaging for Thyroid Cancer

Thyroid nodules are extremely common in the adult population of the United States, and the incidence of thyroid cancer continues to increase. Preoperative ultrasonography is a crucial component of the work up of thyroid nodules. Recent studies evaluating (18)F-2-fluoro-2-deoxy-D-glucose-positron-emission-tomography, with or without simultaneous computed tomography imaging, are encouraging for its potential utility in thyroid cancer in patients who have an elevated serum thyroglobulin level and a negative (131)I scan.

Efficacy of radioiodine therapy in the treatment of elevated serum thyroglobulin in patients with differentiated thyroid carcinoma and negative whole-body iodine scan

INTRODUCTION

In the management of patients with differentiated thyroid carcinoma, serum thyroglobulin levels are often well correlated with whole-body radioiodine scanning (WBS) results. However, occasionally, a mismatched result - increased thyroglobulin with negative WBS - is observed. Radioiodine therapy has been suggested as a therapeutic choice with controversial results.

METHOD

We studied 32 differentiated thyroid carcinoma patients with elevated thyroglobulin level and negative WBS who had been treated with high-dose radioiodine. With a mean follow-up of 25.6 months (all follow-ups >11 months), thyroglobulin and thyroid-stimulating hormone levels, WBS, clinical, radiographic and pathological findings following treatment were recorded.

RESULTS

The mean pre-therapy off-treatment thyroglobulin was 152 +/- 119.0 ng.ml(-1). Although there was a mild trend towards an increase in thyroglobulin in the first post-treatment year, the difference was not significant. At the end of the follow-ups, 22 patients (68.7%) were categorized as non-responders to radioiodine therapy (any change or elevation of thyroglobulin or radiological and pathological evidences of progression), four patients (12.5%) as partial responders (transient reduction but not a normalization of thyroglobulin) and six patients (18.7%) as responders (normalization of thyroglobulin with no evidence of remnant disease). In nine of 10 partial and complete responders, reduction or normalization of thyroglobulin had occurred in the first post-treatment year.

CONCLUSION

We recommend that in differentiated thyroid carcinoma patients with elevated thyroglobulin and negative WBS, at least one course of radioiodine therapy should be undertaken and if reduction or normalization of serum thyroglobulin is not achieved, repeated courses of radioiodine therapy are not logical and other therapeutic methods should be applied.

Long-term course and predictive factors of elevated serum thyroglobulin and negative diagnostic radioiodine whole body scan in differentiated thyroid cancer

Following the initial management, some patients with differentiated thyroid cancer (DTC) develop a state of high thyroglobulin (Tg) and negative diagnostic radioactive iodine (RAI) whole body scan (DxWBS). The predisposing factors and outcome of this condition are unclear. In this study, our objectives were to determine the predictive factors for the development of high Tg and negative DxWBS (Tg+/scan-) and to study the long-term course of the disease in patients with this condition.

METHODS

We, retrospectively, reviewed the medical records of a cohort of 105 non-selected DTC patients (26 males and 79 females; median age 37.7 yr, range 7-72). None of these patients had positive Tg antibodies or distant metastases. All Tg levels were obtained off thyroid hormone therapy. At the first follow-up visit after RAI ablation (13 +/- 7.6 months), patients were classified into those with low Tg (<2 ng/ml off L-T4) and negative DxWBS (control group) and those with high Tg ( > or = 22 ng/ ml off L-T4) and negative DxWBS (Tg+/scan- group). Using univariate and multivariate logistic regression analyses, we evaluated a number of parameters (see results) for their association with the development of Tg+/scan-. In addition, the long-term course of the disease in Tg+/scan- group was analyzed.

RESULTS

In univariate analysis, the following factors were found to be significantly associated with Tg+/scan-: perithyroidal tumor extension (p=0.025), soft tissue invasion (p=0.001), cervical lymph node metastases (p=0.014) and Tg level before RAI ablation (p=0.015). In multivariate analysis, only soft tissue invasion remained significantly associated with Tg+/scan- [p 0.001, odds ratio, 15.6 (95% Cl, 2.96-82.06)]. Age, sex, duration of goiter before surgery, pressure symptoms, tumor size, tumor multifocality, lymph nodedissection at initial surgery, tumor-node-metastasis (TNM) stage, and RAI ablative dose were not associated with Tg+/ scan-. In 53 patients with Tg+/scan-, 42 cases were followed without any therapeutic intervention; over a median follow-up of 71.6 months (range, 13-144.7), 31 cases had a spontaneous remission and 11 cases continued to have a persistent disease (Tg > or = 2 ng/ml, negative DxWBS, and no palpable disease or distant metastases); Tg declined from 9.32 +/- 9.91 ng/ml at first visit after RAI ablation to 1.59 +/- 5.39 ng/ml at last visit (p<0.0001). In the other 11 cases of Tg+/scan- group, one or more therapeutic interventions (RAI, surgery, or external radiotherapy) were undertaken. Over a median follow-up of 98.4 months (range, 6-147), Tg decreased from 110.2 +/- 147.5 to 23.5 +/- 41.2 ng/ml (p 0.026); 4 cases achieved remission, 5 cases continued to have persistent disease, and 2 cases had progression of their disease, which led to their death.

CONCLUSION

Soft tissue invasion on original surgery strongly predicts the development of Tg+/scan- in DTC patients. The long-term course of the disease is mostly favorable especially when the Tg level is only modestly elevated.

TSH recombinante no tratamento e seguimento de pacientes com carcinoma diferenciado de tireóide: uso na prática clínica

Os estudos que avaliaram a eficácia e segurança do TSH recombinante no preparo dos pacientes com carcinoma diferenciado de tireóide (CDT) para o tratamento ablativo e no seguimento com tireoglobulina sérica (Tg) e varredura de corpo inteiro com iodo-131 foram revisados neste artigo. No acompanhamento após a terapia inicial, o TSH recombinante é eficaz na geração da Tg e para realização da varredura de corpo inteiro com radioiodo e apresenta vantagens sobre o hipotireoidismo iatrogênico, poupando os pacientes dos sintomas de hipotireoidismo e da piora da qualidade de vida induzida pela suspensão da levotiroxina, resultando em menor exposição a um TSH elevado, e reduzindo o período de afastamento das atividades. TSH recombinante é a forma de preparo indicada para o diagnóstico de metástases, tanto em pacientes de baixo (Tg após TSH recombinante), quanto de moderado ou alto risco (Tg e varredura com iodo-131 após TSH recombinante). Para terapia ablativa, os resultados são promissores com a dose de 100mCi na ablação de remanescentes, mas o hipotireoidismo ainda é preferível, exceto em pacientes que não alcançam a elevação desejada do TSH após a retirada da levotiroxina, com doenças de base que são agravadas pelo hipotireoidismo agudo e severo (cardiopatia e doença pulmonar graves, coronariopatia, função renal comprometida, passado de psicose por mixedema), indivíduos debilitados por doença avançada e idosos. Os estudos também mostram que a administração do TSH recombinante é segura, com poucos efeitos adversos leves ou moderados.

Abordagem dos pacientes com carcinoma diferenciado de tireóide com tireoglobulina sérica elevada e pesquisa de corpo inteiro negativa

No seguimento do carcinoma diferenciado de tireóide (CDT), o achado de tireoglobulina (Tg) elevada e pesquisa de corpo inteiro (PCI) diagnóstica negativa não é incomum. Em 12% dos nossos pacientes tratados com tireoidectomia e radioiodo com Tg >10ng/ml em hipotireoidismo apresentou PCI diagnóstica negativa. Este achado geralmente indica resultado falso-negativo da PCI. Devem ser excluídos exposição inadequada ao excesso de iodo e elevação insuficiente do TSH. Micrometástases que não captam o suficiente para serem detectadas com baixa atividade de radioiodo e perda da capacidade de expressar o simportador sódio/iodeto (NIS) também explicam alguns casos. Em pacientes com Tg elevada, metástases podem ser reveladas após uma dose terapêutica de radioiodo (100mCi ou mais), estando esta indicada nos casos com Tg maior que 10ng/ml em hipotireoidismo ou 5ng/ml com TSH recombinante, após exclusão de macrometástases pulmonares e cervicais. Cinco de 7 pacientes com estes critérios apresentaram captação ectópica na PCI pós-dose em nossa série. Se a PCI pós-dose for negativa ou revelar captação discreta em leito tireoidiano, outros métodos, por exemplo FDG-PET, podem ser utilizados, não se insisitindo na radioiodoterapia. Para estes casos, outras modalidades terapêuticas (cirurgia, radioterapia, quimioterapia, ácido retinóico) podem ser utilizadas. Se a PCI revelar metástases linfonodais, cirurgia é a terapia mais adequada; enquanto para metástases pulmonares difusas indica-se a radioiodoterapia até a negativação da PCI pós-dose ou normalização da Tg com TSH elevado. Pacientes com PCI pós-dose positiva podem apresentar redução significativa da Tg e até remissão completa com radioidodoterapia em alguns casos, mas o impacto deste tratamento na mortalidade permanece indefinido.

I-131 therapy for thyroglobulin positive patients without anatomical evidence of persistent disease

OBJECTIVE

the aim of this retrospective study was to evaluate the diagnostic relevance of I-131 whole body scan (WBS) performed after second empirical therapeutic doses of iodine-131 (I-131) in thyroglobulin (Tg)-positive thyroid cancer patients without evidence of local and distant metastasis. We also evaluated the efficacy of second empirical therapeutic doses of I-131 in these patients.

METHODS

we retrospectively compared the results of diagnostic I-131 WBS and post-therapy scans of second therapeutic doses of I-131 in 38 patients with detectable Tg while off T4 therapy (TSH>25 mlU/ml). All patients underwent a near-total or total thyroidectomy and I-131 ablation with 75-125 mCi. All of the reported subjects had no prior evidence for detectable disease before second high dose empirical I-131 therapy.

RESULTS

there was almost complete concordance in uptake between diagnostic I-131 WBS and final scans carried out after second I-131 therapy in 22 out of 38 patients. Whereas abnormal foci of new uptake was detected in all of the remaining 16 patients, seven of them were found to have negative diagnostic WBS results. Distant metastases were observed in 3 of 16 subjects and mediastinal uptake was found in 2 of 16 patients in post-therapy scan. During the subsequent follow-up, extending from 8-46 months, 6 out of 16 patients showed normalization of serum Tg levels while off T4. Serum Tg levels were normalized in 3 out of 7 patients who had negative WBS results, increased in one and unchanged in the remaining 3. None of the patients with distant metastases had normalization of Tg levels. Totally, 6 out of 38 showed normalization of Tg levels while off T4 therapy.

CONCLUSION

the empirical therapeutic doses of 1-131 may help in localization of the disease in Tg positive patients without anatomical evidence of persistent disease, but the effect of I-131 therapy on long-term survival is not obvious.

Effects of therapeutic doses of 131I in thyroid papillary carcinoma patients with elevated thyroglobulin level and negative 131I whole-body scan: comparative study

OBJECTIVE

Previous studies have shown a high rate of visualization of uptake and a decrease in serum thyroglobulin (Tg) after therapeutic doses of 131I in well-differentiated thyroid cancer patients with elevated thyroglobulinaemia but negative diagnostic 131I whole-body scan (DxWBS), but its therapeutic effect remains controversial. We evaluate the effect of therapeutic doses of 131I in patients with elevated thyroglobulin level but negative DxWBS.

DESIGN

Among papillary thyroid carcinoma patients who underwent total or near-total thyroidectomy and remnant ablation with radioiodine during 1996 to 2000 in our hospital, the patients who showed elevated serum Tg levels and no abnormal uptake in DxWBS were selected. The selection for treatment or no treatment was decided according to the preference of the patients, considering side-effects of therapeutic doses of 131I, and the patients were thereafter studied retrospectively.

PATIENTS

Sixty papillary thyroid carcinoma patients with elevated thyroglobulinaemia but negative DxWBS were included. Twenty-eight patients were treated, and 32 were untreated.

MEASUREMENTS

We compared serum Tg levels measured at less than 3 months before the administration of therapeutic doses of 131I or DxWBS with the levels at 6-12 months after administration between two groups. Comparable data on changes in serum Tg levels during TSH suppression (Tg-on) and those in hypothyroid phase (Tg-off) were available in 25 and 49 patients, respectively.

RESULTS

Percentage decreases in both Tg-on and Tg-off levels of the treated group [41.2 (10.1-94.1)% and 37.0 (-176.6-88.4)%, respectively] were significantly higher than those of the untreated group [-43.6 (-180.1-7.3)% and -66.6 (-10644.2-39.1)%, respectively] (P < 0.001). The treated patients were followed-up for 23.8 +/- 19.6 months after the administration of therapeutic doses of 131I. In four cases, serum Tg levels converted to negative (< 1.0 ng/ml) both on and off T4 15-22 months after the administration of therapeutic doses of 131I, and negative serum Tg levels persisted for 24-70 months. However, negative conversion of elevated serum Tg levels was not observed in any of the untreated group. Post-treatment WBS revealed pathologic uptake in 12 of 28 cases (42.9%).

CONCLUSIONS

This study revealed that the administration of therapeutic doses of 131I has a therapeutic effect, at least for palliation in short-term observation, considering the serum Tg level as an index of tumour burden, and that it can disclose previously undiagnosed lesion in some patients with differentiated thyroid cancer who show elevated thyroglobulin level but negative diagnostic 131I whole-body scan.

Combined positron emission tomography/computed tomography imaging of recurrent thyroid cancer

OBJECTIVE

The study goal was to evaluate the use of combined positron emission tomography/computed tomography (PET/CT) imaging for localization of recurrent disease in thyroid cancer patients.

STUDY DESIGN AND SETTING

Eight patients with suspected recurrence of thyroid cancer on the basis of elevated serum thyroglobulin or calcitonin levels underwent combined PET/CT imaging on a prototype device. All 8 patients had previously undergone total thyroidectomy and (131)I ablation for thyroid carcinoma. Patients with papillary carcinoma had negative (131)I scans.

RESULTS

Eight patients underwent combined PET/CT scanning. Four (50%) of 8 patients underwent PET/CT indicating recurrence in the head and neck. A total of 11 lesions in these 4 patients were suspicious for recurrence on combined PET/CT imaging. Three patients with 8 lesions suspicious for recurrence on PET/CT underwent surgical removal of disease. All 3 patients had pathologic confirmation of recurrence, with 6 (75.0%) of 8 lesions being positive.

CONCLUSION

Combined PET/CT imaging is a valuable tool for the diagnosis and anatomic localization of recurrent thyroid cancer.

Postoperative management of differentiated thyroid cancer

The large numbers of studies on the postoperative management of differentiated thyroid carcinoma allows us to use adjuvant treatment and follow-up studies more selectively based on patient risk for recurrence and mortality. Recurrent differentiated thyroid carcinoma is more easily and more effectively treated with early diagnosis. With this in mind, patients who are at high risk for life-threatening recurrent disease should be treated aggressively and followed up expectantly. In these patients, adjuvant treatment with 131I ablation and thyroid hormone suppression is appropriate. External irradiation may be considered, especially for patients with postoperative residual disease. Close follow-up with stimulated thyroglobulin and 131I whole body scans should be performed to facilitate early detection of recurrent disease. Low-risk patients may be effectively treated with more conservative management. 131I ablation has not resulted in improved survival in these patients. Follow-up with serum thyroglobulin after initial negative 131I whole body scan may be appropriate in these patients. Management of patients at intermediate risk remains controversial. Recombinant human thyrotropin allows us to obtain stimulated serum thyroglobulin and promises the ability to perform 131I ablation and whole body scan without the need for thyroid hormone withdrawal. Functional radionuclide imaging, such as FDG PET, now allows us to localize recurrent disease in patients with elevated serum thyroglobulin but negative 131I scan.

Recurrent differentiated thyroid carcinoma: biological implications of age, method of detection, and site and extent of recurrence

BACKGROUND

We identified factors predictive of outcome for recurrent differentiated thyroid carcinoma (DTC).

METHODS

Fifty-seven patients with local (LR), regional (RRec), and/or distant recurrence (DR) of 431 recurrent DTCs were studied. Disease-specific survival (DSS) rate was estimated with the Kaplan-Meier method. Univariate and multivariate comparisons were conducted by log-rank and Cox regression analysis.

RESULTS

The median follow-up was 13 years. Distribution of the first relapse was LR only (35%), LR and RRec (23%), LR and DR (30%), and LR, RRec, and DR (12%). Factors predictive of resectability were a long (>or=5-year) disease-free interval (DFI) and subclinical and thyroid remnant recurrence. Only 26% of symptomatic and 45% of thyroid bed LR, and 43% with DFI <5 years, could be resected completely. No isolated thyroid remnant and 75% of thyroid bed LR resulted in tumor-related mortality. Age <45 years, subclinical recurrence, isolated LR, and the ability to render the patient disease free independently predicted DSS. Fifteen-year DSS for LR only; LR and RRec; LR and DR; and LR, RRec, and DR were 49%, 28%, 15%, and 0%, respectively.

CONCLUSIONS

Isolated thyroid remnant recurrence defines a benign phenotype. Age, method of detection, site and extent of recurrence, and the ability to render the patient disease free predict outcome for recurrent DTC. Multimodality long-term follow-up is warranted to detect recurrence at a subclinical potentially curative stage.

Clinical comparison of whole-body radioiodine scan and serum thyroglobulin after stimulation with recombinant human thyrotropin

Sensitive monitoring for thyroid cancer recurrence or persistence includes whole-body radioiodine scanning (WBS) and measurement of serum thyroglobulin (Tg) after endogenous or exogenous thyrotropin (TSH) stimulation. We reviewed our experience using recombinant human thyrotropin (rhTSH) in 83 patients to compare the clinical relevance of a positive WBS and/or Tg. Ten patients had a positive WBS; eight of these patients had activity limited to the thyroid bed. rhTSH-stimulated Tg was 2 ng/mL or more in 25 and 5 ng/mL or more in 13 patients. Of the patients with a negative WBS, 11 of 20 patients with a Tg 2 ng/mL or more and 7 of 9 patients with a Tg 5 ng/mL or more received therapy or further evaluation based on the Tg alone. Conversely, only 1 of 5 patients with a serum Tg less than 2 ng/mL received therapy or further evaluation based on a positive WBS alone. Three of the patients who did not receive therapy or further evaluation, had subsequent negative WBS 10-12 months later, suggesting lack of clinically significant disease. Twenty patients had a negative WBS and serum Tg 2 ng/mL or more. Eleven of 20 patients had a Tg less than 5 ng/mL and 4 of these patients had further evaluation with a neck ultrasound. One patient had a biopsy-proven recurrence (rhTSH-stimulated Tg 4 ng/mL). Subsequent evaluations (> or = 6 months later) have been negative for 8 patients. Of the nine patients with a Tg 5 ng/mL or more and a negative WBS, 7 had further evaluation and 6 of 7 had identified disease. In summary, rhTSH-stimulated WBS and Tg are complementary, but Tg is a more sensitive indicator of disease recurrence or persistence. In our practice, an rhTSH-stimulated Tg greater than 4-5 ng/mL often resulted in further evaluation, while a Tg less than 4 ng/mL rarely resulted in further immediate evaluation.

Outcome of differentiated thyroid cancer with detectable serum Tg and negative diagnostic (131)I whole body scan: comparison of patients treated with high (131)I activities versus untreated patients

Detectable serum Tg levels associated with negative diagnostic (131)I whole body scan are not infrequently found in patients with differentiated thyroid cancer. Several researchers have shown that in these patients the administration of high (131)I activity (100 mCi or more) increases the sensitivity of a posttherapy diagnostic (131)I whole body scan performed a few days later and allows the detection of neoplastic foci not seen with diagnostic doses of (131)I. Empirical radioiodine treatment has also been advocated by some researchers, but its therapeutic effect is controversial. In our institute, positive serum Tg/negative diagnostic (131)I whole body scan patients were not treated with high (131)I activities before 1984; afterward, almost all patients with positive serum Tg/negative diagnostic (131)I whole body scan patients were treated with radioiodine, and a posttherapy diagnostic (131)I whole body scan was performed. In the present retrospective study we compared the outcome of these two groups of patients, 42 treated and 28 untreated, followed for mean periods of 6.7 +/- 3.8 and 11.9 +/- 4.4 yr, respectively. In the treated group the first posttherapy diagnostic (131)I whole body scan was negative in 12 patients and positive in 30 patients. (131)I treatment was further administered only in the latter group. At the end of follow-up in treated patients a complete remission (normalization of serum Tg off L-thyroxine and negative diagnostic (131)I whole body scan) was observed in 10 patients (33.3%). In 9 cases (30%) posttherapy diagnostic (131)I whole body scan became negative, and serum Tg was reduced but still detectable; in 11 patients (36.6%) serum Tg was detectable, and posttherapy diagnostic (131)I whole body scan was positive. The resolution of (131)I uptake in lung metastases was observed in 8 of 9 cases (88.8%) and in cervical node metastases in 11 of 18 cases (61.1%). In patients treated only once because the posttherapy diagnostic (131)I whole body scan was negative (n = 12), 2 patients (16.7%) were in apparent remission, 7 (58.3%) had detectable Tg values without evidence of disease, 2 (16.7%) showed lymph node metastases in the mediastinum, and 1 patient (8.3%) died because of lung metastases. Of the 28 untreated patients, none with radiological evidence of disease, serum Tg off L-thyroxine therapy became undetectable in 19 cases (67.9%), significantly reduced in 6 cases (21.4%), and unchanged or increased in 3 patients (10.7%), 1 of whom developed lung metastases 14 yr after the diagnosis. In summary, our results indicate that in patients with detectable serum Tg and negative diagnostic (131)I whole body scan, treatment with high doses of (131)I may have therapeutic utility in patients with lung metastases and, to a lesser extent, in those with lymph node metastases. However, in view of the frequent normalization of Tg values in untreated patients, we believe that treatment with (131)I should be considered according to the result of the first posttherapy scan. If positive in the lung, (131)I treatment should be continued up to total remission; surgical treatment should be preferred in patients with node metastases, and no treatment should be used in those with thyroid bed uptake or no uptake.

Ultrasound-guided fine-needle aspiration biopsy of the thyroid bed

BACKGROUND

Ultrasound (US) has been shown to be a sensitive technique for monitoring patients for recurrent thyroid carcinoma in the thyroid bed after total thyroidectomy. However, the role of US-guided fine-needle aspiration biopsy (FNAB) in the confirmation of sonographically indeterminate or suspicious masses has not been adequately addressed. The purposes of this study were to determine the sensitivity and specificity of US-guided FNAB of the thyroid bed for diagnosing recurrent carcinoma after total thyroidectomy and to highlight potential diagnostic pitfalls.

METHODS

Twenty-one patients with a history of total thyroidectomy and histologically confirmed thyroid carcinoma who had undergone US-guided FNAB of hypoechoic lesions in the thyroid bed were included in this retrospective study. Fifteen of the 21 had papillary carcinoma (PC), 5 had medullary carcinoma (MC), and 1 had Hürthle cell carcinoma (HTC). The cytologic features of the aspirates were compared with histopathologic findings of pre- and post-FNA surgery. Immunohistochemical staining for thyroglobulin, calcitonin, and parathyroid hormone was performed in four cases.

RESULTS

The cytologic diagnosis from the US-guided FNABs was conclusive in 20 of 21 cases. Fifteen cases were diagnosed as recurrent tumor (12 PC, 2 MC, and 1 HTC), and 13 of the 15 were confirmed subsequently by histology. Five cases were diagnosed as benign (two residual benign thyroid tissue, one parathyroid gland [PG] tissue, and two reparative changes) and hence were not resected. There was one false-positive diagnosis in which PG was misdiagnosed as PC. Immunohistochemical studies helped to confirm the diagnosis of PG tissue in two cases and of MC in two cases. The sensitivity of US-guided FNA for diagnosing recurrent carcinoma in the thyroid bed after total thyroidectomy was 100% and the specificity was 85.7%.

CONCLUSIONS

US-guided FNAB was found to be a sensitive and specific test for diagnosing sonographically indeterminate lesions in the thyroid bed. One potential diagnostic pitfall was the misdiagnosis of normal residual thyroid or PG tissue as recurrent tumor. Careful attention to cytologic details and the use of selected immunohistochemical staining may help to prevent these misdiagnoses.

Isotopic evaluation and therapy in patients with malignant endocrine disease

The contribution of nuclear medicine to the diagnosis and treatment of endocrine malignancy is increasing. Advances in molecular biology offer new opportunities for tumour targeting via surface receptor recognition and tumour-specific metabolic markers. Imaging the biodistribution of these markers allows quantitative, in vivo characterization of tumour function. There is growing interest in the therapeutic potential of nuclear medicine targeting, substituting therapeutic beta-emitting radionuclides for the gamma-emitters used in diagnostic imaging. Limited clinical experience supports the rationale of this approach in patients with inoperable or disseminated disease and controlled trials are in progress. This chapter outlines the place of nuclear medicine techniques in the routine management of endocrine malignancy and explores areas for further development.

An audit of management of differentiated thyroid cancer in specialist and non-specialist clinic settings

OBJECTIVE

Thyroid cancer is the most common endocrine malignancy but is none the less rare. Some aspects of its management remain controversial. Previous audits of patient management in the United Kingdom have revealed deficiencies, especially in communication between specialists. We have audited patient management in a large university-associated teaching hospital, assessing points of good practice identified from published guidelines and reviews, and have compared findings in groups of patients managed jointly by specialists with an interest in thyroid cancer (including surgeon, endocrinologist and oncologist) with a group managed by other clinicians outside that setting.

DESIGN AND PATIENTS

Retrospective case-note review of 205 patients with differentiated (papillary or follicular) cancer including group A (n = 134; managed in a specialist multi-disciplinary clinic setting) and group B (n = 71; managed in other clinic settings). Points of good practice investigated were adequacy of surgery, surgical complications, prescription and adequacy of T4 treatment, adequacy of monitoring by measurement of serum thyroglobulin and action taken and appropriate administration of ablative radioiodine.

RESULTS

Deficiencies in management of the cohort as a whole were identified, including inadequate surgery and inadequate TSH suppression in approximately one-fifth of the cases. Monitoring with thyroglobulin measurements and action when serum thyroglobulin was high were also inadequate in some cases and ablative radioiodine was not given, despite being indicated in 11.7% of the cohort. Inadequate surgery and failure to administer radioiodine were less common in those managed in a specialist clinic setting than in those managed in other clinic settings.

CONCLUSIONS

The findings highlight the need for locally agreed protocols in managing relatively rare endocrine disorders such as thyroid cancer and argue in favour of centralization of expertise and patient management in multi-disciplinary specialist clinic settings.

Serum thyroglobulin measurement. Utility in clinical practice

Serum thyroglobulin measurement has greatly facilitated the clinical management of patients with differentiated thyroid cancer and a variety of other thyroid disorders. Thyroglobulin autoantibodies remain a significant obstacle to the clinical use of thyroglobulin measurement. The interpretation of any given thyroglobulin value requires the careful synthesis of all pertinent clinical and laboratory data available to the clinician. The diagnostic use of rhTSH-stimulated thyroglobulin levels has greatly facilitated the follow-up of low-risk patients with thyroid cancer. Although the measurement of thyroglobulin mRNA from peripheral blood is likely to affect the future management of these patients, it is expected that serum thyroglobulin measurement will continue to have a principal role in the care of patients with differentiated thyroid cancer.

Outcome after treatment for papillary thyroid cancer

BACKGROUND

To evaluate the results of treatment and the prognostic variables of papillary thyroid carcinoma patients after long-term follow-up.

PATIENTS AND METHODS

Retrospective review of 1,373 thyroid cancer patients. Of the 1,016 papillary thyroid cancer patients, 394 patients received follow-up for more than 5 years, including 305 women (mean age, 38.4 +/- 13.7 years) and 89 men (mean age, 44.0 +/- 13.4 years). Of these papillary thyroid carcinoma patients, 227, 76, 68, and 23 patients were categorized in clinical stages I, II, III, and IV, respectively, at the time of diagnosis.

RESULTS

After treatment, 36 (9.1%) patients died. Only 23 (5.8%) of them died of papillary thyroid carcinoma. The 1-, 5-, 10-, and 20-year survival rates were 0.980, 0.951, 0.901, and 0.731. Mortality factors of the papillary thyroid carcinoma patients related to age, gender, tumor size, and postoperative serum thyroglobulin (Tg) levels. Twenty-four patients progressed from clinical stages I, II, and III to stage IV during the follow-up period. Of these 24 patients, 12 died during the follow-up period. In this study, age, gender, 131I accumulated dose, postoperative serum Tg levels, and the survival rate were demonstrated to be statistically significant between the patients in early stage and advanced stage groups after treatment.

CONCLUSION

Twenty-four of the 47 papillary thyroid cancer patients with distant metastases were diagnosed during the follow-up period. This study suggests that distant metastasis may occur at a serum Tg level of 2.3 ng/mL with thyroxine replacement. Postoperative long-term close follow-up of these patients is recommended.

Familial nonmedullary thyroid cancer

Familial nonmedullary thyroid cancer is more aggressive than sporadic nonmedullary thyroid cancer. It tends to affect younger patients, and the tumors are often multi-focal and bilateral. Histologically, 90% of these tumors are papillary cancers and the remaining are Hürthle cell cancers. We recommend total thyroidectomy to remove all the thyroid tissue, which harbors the genetic defect responsible for the disease (even in low-risk patients) due to the predisposition to develop thyroid cancer and the more aggressive nature of the disease. Careful exploration of the ipsilateral lymph nodes with ipsilateral central neck dissection is encouraged to decrease a high recurrence rate (44%). A complete modified radical neck dissection should be limited to a therapeutic role because there is no clear evidence that this procedure carries any survival benefit. We also recommend that patients receive radioactive iodine ablation post-operatively, including a prophylactic dose (30 mCi) for patients with no evidence of residual uptake on the postoperative iodine 131 whole body scan and in low-risk patients using any of the prognostic scoring systems. Patients should be placed on enough thyroid hormone to suppress thyroid-stimulating hormone (TSH) to approximately 0.1 mL/mL in low-risk patients and to less than 0.1 mL/mL in high-risk patients. Focal metastatic disease in patients with familial nonmedullary thyroid cancer is best dealt with by surgical excision followed by radioactive iodine ablation when appropriate. Redifferentiation therapy has a promising role in patients who have radioactive iodine-resistant tumors. The value of prevention, early detection, and targeted gene therapy once the gene or genes responsible for familial non-medullary thyroid cancer have been identified cannot be overemphasized.

Serum thyroglobulin levels after thyroxine withdrawal in patients with low risk papillary thyroid carcinoma

We hypothesized that elevated levels of serum thyroglobulin (Tg) are frequently found as the only index of residual neoplasm in patients with low-risk papillary thyroid carcinoma. The records of patients operated on for papillary thyroid carcinoma over a 2-year period were reviewed, and the patients were allocated to risk groups by a validated staging method that does not include Tg levels. Of the 35 patients who manifested a low-risk carcinoma, 9 (26%) exhibited elevated Tg concentrations (11-53 ng/mL) during thyroxine withdrawal after therapies, while clinical, scintigraphic, and radiographic studies at least 1 year later showed no evidence of tumor. Prior scintigraphic imaging of therapeutic doses of 131I in 8 of 9 patients demonstrated no distant metastases, further confirming the low-risk status of this group. The staging method predicts that only 0.9% of patients with low-risk papillary carcinoma will have a cause specific death in 20 years. Elevated Tg concentrations have not been shown to forecast independently the survival of patients with low-risk papillary carcinoma. Thus, although frequently encountered, elevated Tg concentrations are unlikely to predict shortened survival in patients with papillary carcinoma for whom low risk has been determined from other data.

Recurrent differentiated thyroid cancer without elevation of serum thyroglobulin

Thyroglobulin (Tg) is a reliable tumor marker in patients with well-differentiated thyroid cancer (WDTC). We identified 11 patients who had undetectable serum Tg and no thyroglobulin antibody (TgAb) in the presence of clinical disease. Three had residual disease after ablation of the thyroid by surgery plus radioiodine and 8 relapsed after a disease-free interval. Histologic review confirmed that 7 of the tumors were papillary carcinomas and 4 were follicular carcinomas. Immunohistochemical staining for Tg was positive in 6 of 7 papillary and in 3 of 4 follicular carcinomas. There were no identifiable histologic or clinical features that could be used to predict further patients who may relapse with absence of this serum marker. Negative serum Tg did not appear to be an adverse prognostic feature. During follow-up, measurement of Tg and TgAb should be supplemented by radioiodine scanning and radiological imaging in patients in whom recurrence is likely or suspected.

Factors related to the survival of papillary and follicular thyroid carcinoma patients with distant metastases

There is limited clinical information comparing presentations and results of treatment of papillary and follicular thyroid carcinoma patients with distant metastases. We retrospectively analyzed data of 1,257 thyroid cancer patients who received their treatment and follow-up at Chang Gung Memorial Hospital. We found 992 patients with papillary carcinoma and 205 patients with follicular thyroid carcinoma. Of these, 68 patients with papillary thyroid carcinoma (6.9%) had distant metastases at the time of diagnosis or during the follow-up period. Of the follicular thyroid carcinoma patients, 69 (33.7%) had distant metastases. Of the 68 patients with papillary carcinoma, only 33 were categorized as stage IV at the time of diagnosis. Nine of the patients were categorized as clinical stage I carcinoma, 10 as stage II, and 16 as stage III. Sixteen patients (23.5%) died during the study period, all but 2 of thyroid cancer. Twelve of the 68 patients were disease-free after treatment. Of the 69 patients with follicular thyroid carcinoma, 58 were categorized as stage IV at the time of diagnosis. Six of the patients were categorized as clinical stage I carcinoma, 2 as stage II, and 3 as stage III at the time of diagnosis; all of these patients deteriorated to stage IV during the follow-up period. Of the 42 patients with follicular thyroid carcinoma involving bone, 24 presented with bone metastases during the initial diagnosis. After treatment, 25 of 69 patients with follicular carcinoma died of follicular carcinoma. Only 3 patients were disease-free after the treatment. In patients with follicular carcinoma, only tumor size was an important prognostic factor. In this study, 8 patients categorized as clinical stages I to III at the time of operation had thyroglobulin (Tg) levels less than 5 ng/mL and developed distant metastases during the follow-up period. In conclusion, at diagnosis a large group of Asian patients with metastatic well-differentiated thyroid cancer was more likely to have follicular than papillary histology, and that, as expected, metastases from follicular cancer were present earlier and more frequently, were more likely to involve bone, were more likely to be associated with mortality, and were linked to tumor size but not gender. Also unlike some other reports, treatment producing a low Tg did not always produce a good outcome. More aggressive surgical procedures may be able to improve outcomes.