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

Thyroid lobe ablation with radioactive iodine as an alternative to completion thyroidectomy after hemithyroidectomy in patients with follicular thyroid carcinoma: long-term follow-up

BACKGROUND

Radioactive iodine lobe ablation (RAI-L-ABL) is a possible alternative to completion thyroidectomy (C-Tx) for follicular thyroid carcinoma (FTC), but no long-term outcome data are available after lobe ablation. We analyzed the long-term outcome of lobe ablation in a series of patients with FTC.

METHODS

This was a retrospective study of patients who were treated with lobe ablation between 1983 and 2008. Of 134 patients with FTC, 37 (27.6%) had lobe ablation with (131)I (30-32 mCi) (RAI-L-ABL), 68 (50.7%) had C-Tx, and 29 (21.6%) had initial total thyroidectomy (T-Tx). The main outcomes analyzed were (131)I uptake after lobe ablation, C-Tx or T-Tx, serum thyroglobulin (Tg), serum thyroid-stimulating hormone (TSH), long-term disease-specific mortality, and disease-free survival.

RESULTS

After lobe ablation, radioiodine uptake was significantly lower for the RAI-L-ABL group (0.6%) than for the C-Tx group (2.0%, p<0.005) or T-Tx group (1.3%, p=0.054). Subsequent remnant ablation was performed in 12 of 37 (32%) patients in the RAI-L-ABL group, in 58 of 68 (85.3%) patients in the C-Tx group, and in 25 of 29 (86.2%) patients in the T-Tx group (p<0.01). With median follow-up of 95 months for the RAI-L-ABL group, 47 months for the C-Tx group, and 53 months for the T-Tx group, there was one death in the RAI-L-ABL group and one death in the T-Tx group. No other RAI-L-ABL patients had detectable disease, whereas patients in the C-Tx group and two patients in the T-Tx group had detectable disease (p=0.18). Long-term stimulated or suppressed Tg of <1 ng/mL were found in 87.5% of the RAI-L-ABL group (n=28), 86.3% of the C-Tx group (n=57), and 77.8% of the T-Tx group (n=21). Tg was detectable in 40.6% of the RAI-L-ABL group compared to 13.8% of C-Tx and 28.6% of T-Tx groups (p<0.05, between groups).

CONCLUSIONS

RAI-L-ABL, C-Tx, and T-Tx are equally effective in achieving serum TSH concentrations of >25 mIU/L and preparing patients for conventional (131)I treatment and whole body scanning with similar long-term outcomes. However, persistent measurable Tg (range 0.2-2.2 ng/mL) is more common after RAI-L-ABL.

Differentiated thyroid cancer: management of patients with radioiodine nonresponsive disease

Differentiated thyroid carcinoma (papillary and follicular) has a favorable prognosis with an 85% 10-year survival. The patients that recur often require surgery and further radioactive iodine to render them disease-free. Five percent of thyroid cancer patients, however, will eventually succumb to their disease. Metastatic thyroid cancer is treated with radioactive iodine if the metastases are radioiodine avid. Cytotoxic chemotherapies for advanced or metastatic noniodine avid thyroid cancers show no prolonged responses and in general have fallen out of favor. Novel targeted therapies have recently been discovered that have given rise to clinical trials for thyroid cancer. Newer aberrations in molecular pathways and oncogenic mutations in thyroid cancer together with the role of angiogenesis in tumor growth have been central to these discoveries. This paper will focus on the management and treatment of metastatic differentiated thyroid cancers that do not take up radioactive iodine.

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").

Successful management of differentiated thyroid cancer in a community-based endocrine practice

OBJECTIVE

To describe the range of differentiated thyroid cancer (DTC) cases, disease complexity, and treatment outcomes seen in our 3-physician community-based general endocrine practice during an 8-year period in order to make comparisons with published cohorts from university settings.

METHODS

Medical records of patients with DTC treated between 2002 and 2009 at Mountain Diabetes and Endocrine Center (Asheville, North Carolina) were reviewed. Pathologic features, staging, and disease status at last contact were determined. Multivariate analyses of adverse prognostic risk factors at diagnosis, recombinant human thyroid-stimulating hormone use, and radioiodine use were compared with the ultimate outcome of patients.

RESULTS

We treated a total of 167 patients with DTC during the study period (mean age at diagnosis, 44.4 years; mean duration of follow-up, 6.2 years). In our study cohort, 88.6% had papillary thyroid cancer, 74% had stage I disease, and 32.4% of those with papillary thyroid cancer had microscopic tumors (≤1 cm). Remission occurred in 67.1%, 17.1% had persistent disease, and 11.8% were indeterminate for remission; non-thyroid cancer death occurred in 2.6% and disease-specific death in 1.3%. The mean number of adverse prognostic risk factors per patient was 2.0 in those with remission and 4.7 in those with persistent disease.

CONCLUSION

Community-based endocrinologists evaluate the full spectrum of thyroid cancer disease complexity and can achieve excellent outcomes. In our current study group, disease persistence and disease-specific death occurred in 17.1% and 1.3%, respectively. Individualization of care based on prognostic variables guided our diagnostic and therapeutic decisions.

An individualized approach to the child with thyroid cancer

Children with differentiated thyroid cancer (DTC) often present with extensive disease that inclined clinicians in prior decades toward aggressive treatment including total thyroidectomy, radical neck dissection and universal prescription of radioactive iodine (RAI). Recent series with 40 years of follow-up have shown that fewer than 2% of children ultimately die from DTC, but they may have increased all-cause mortality from second malignancies that might be related to previous radiation exposure. In this article, we review data to support the notion that an individualized, risk-stratified approach to therapy should be used for children with DTC. Ideally this will provide aggressive therapy for those in whom aggressive treatment is warranted, but withhold aggressive and risk-associated therapy from those who are not likely to benefit.

Empiric high-dose 131-iodine therapy lacks efficacy for treated papillary thyroid cancer patients with detectable serum thyroglobulin, but negative cervical sonography and 18F-fluorodeoxyglucose positron emission tomography scan

CONTEXT

Some patients with elevated serum thyroglobulin (Tg) but a negative diagnostic whole body scan (WBS) after initial therapy for differentiated thyroid carcinoma may benefit from empirical radioactive iodine (RAI) therapy. However, previous studies enrolled patients with negative diagnostic WBS, regardless of neck ultrasonography (USG) and/or (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), which have become the preferred diagnostic procedures in such patients.

OBJECTIVE

The aim of this study was to evaluate the usefulness of empirical RAI therapy in patients with elevated stimulated Tg level and negative USG/FDG-PET findings after initial therapy for papillary thyroid carcinoma (PTC).

DESIGN

This comparative study enrolled 39 patients with elevated stimulated Tg, negative diagnostic WBS, and negative USG/FDG-PET 1 yr after initial treatment. Empirical RAI therapy was performed in 14 patients (treatment group), whereas 25 patients were followed up without therapy (control group).

RESULTS

There was no significant between-group difference in basal clinicopathological parameters. None of the 14 patients in the treatment group showed iodine uptake on posttreatment WBS. Five of 14 patients (36%) in the treatment group and eight of 25 (32%) in the control group had recurrence during the median 37 months of follow-up (P = 0.99). Changes in serum stimulated Tg concentrations did not differ between the two groups.

CONCLUSION

Empirical RAI therapy and posttreatment WBS were not useful diagnostically or therapeutically in patients with positive serum stimulated Tg if such patients had negative USG and negative FDG-PET findings after initial treatment of PTC.

Radioiodine concentration by the thymus in differentiated thyroid carcinoma: report of five cases

The radioactive iodine has been used with great value as a diagnostic and therapeutic method in patients with differentiated thyroid carcinoma previously submitted to total thyroidectomy. False-positive whole-body scans may occur due to misinterpretation of the physiologic distribution of the radioisotope or lack of knowledge on the existence of other pathologies that could eventually present radioiodine uptake. Thymic uptake is an uncommon cause of false-positive whole-body scan, and the mechanism through which it occurs is not completely understood. The present paper reports five cases of patients with differentiated thyroid cancer who presented a mediastinum uptake of radioiodine in a whole-body scan during follow-up. The patients had either histological or radiological confirmation of the presence of residual thymus gland. It is very important to know about the possibility of iodine uptake by the thymus in order to avoid unnecessary treatment, such as surgery or radioiodine therapy.

[Risk factors of persistent disease at 5 years from diagnosis in differentiated thyroid cancer: study of 63 patients]

OBJECTIVE

To identify possible risk factors associated with persistent disease 5 years after total or near-total thyroidectomy in patients with differentiated thyroid cancer (DTC).

PATIENTS AND METHOD

Retrospective study evaluating data from 63 patients 5 years after they were first diagnosed of DTC. At this time of the study, 46 subjects were considered disease-free (F group) whereas 17 had evidence of persistent disease or had died from DTC (P group). We compared both groups of patients regarding the following variables: a) variables at diagnosis related to the patient (age, gender) and the tumor (histological type, size, extrathyroidal involvement, vascular invasion, multifocality, lymph node and distant metastases), and b) variables recorded during follow-up: percentage of subjects showing serum stimulated thyroglobulin > or = 10 ng/ml few weeks postoperatively (Tg0) and 6 to 12 months later (Tg1).

RESULTS

Male gender, extrathyroidal involvement and lymph node metastases were more frequent in P group than in F group (41 vs. 11%, 60 vs. 18% and 50 vs. 5.5%; p < 0.05). During the follow-up the percentage of patients showing Tg > or = 10 ng/ml was higher in P group compared to F group, both at a few weeks postoperatively and 6 to 12 months later (Tg0, 75 vs. 13%; Tg1, 69% vs. 0; p < 0,05).

CONCLUSIONS

In our patients, male gender, extrathyroidal involvement, and lymph node metastases at diagnosis were associated with persistent disease 5 years later. Serum stimulated thyroglobulin had a very high predictive value both just after surgery and in the next 6 to 12 months and could help identifying subjects who need a closer follow-up.

Thyrotropin variations may explain some positive radioiodine therapy scans in patients with negative diagnostic scans

Thyroglobulin (Tg) is a specific marker of residual thyroid cancer or tumor recurrence. In patients with elevated Tg levels and negative diagnostic radioiodine (131I) whole-body scans (dWBS), administration of a therapy dose may reveal foci that were not initially apparent. The aim of this study was to identify factors, other than 131I activity, which might explain why a post-therapy 131I whole-body scan is sometimes positive despite a negative dWBS.

PATIENTS AND METHODS

We reviewed data on all patients with elevated Tg levels and negative dWBS with 185 MBq 131I off-T4 at followup, who subsequently received an empiric therapy dose of 3700 MBq of 131I. During a 5-yr period, 22 patients met these criteria. 131I therapy could be given immediately after negative dWBS in 9 patients, with an average of 8 extra days of hypothyroidism. In the other 13 patients, therapy was given an average of 8 months later.

RESULTS

The therapy scan was negative in 16 patients, while it showed uptake in the thyroid bed in 5 patients and distant metastases in two. In the latter two patients, the TSH level was suboptimal at the time of dWBS (9 and 25 microIU/ml), and had risen to 34 and 70 microIU/ml respectively at the time of therapy. Overall, a positive scan following therapy occurred in 7 patients (6/9 patients treated immediately and 1/13 patients treated in a separate setting; p<0.01). In patients with positive therapy scans, the mean TSH level was 73 microIU/ml at the time of dWBS and 103.5 microIU/ml at the time of therapy (41% increase; p<0.05). In patients with negative therapy scans the mean TSH level was 84 microIU/ml at dWBS and 86 microIU/ml at the time of the therapy scan (2% increase).

CONCLUSIONS

Our study suggests that interval increase in TSH level with a longer period of stimulation may have contributed to making the whole-body scan positive at the time of therapy. Nowadays, patients with elevated Tg are directly given a therapy dose of 131I. Special care should be taken when preparing patients who have been on suppressive levothyroxine therapy for a long time, in order to avoid misclassifying the tumor as non-functioning.

Radioiodine therapy for differentiated thyroid carcinoma with thyroglobulin positive and radioactive iodine negative metastases

BACKGROUND

Differentiated thyroid carcinoma with thyroglobulin positive and radioactive iodine negative metastases has been observed in follow-up studies. The management of this condition remains controversial. Most studies support blind radioactive iodine treatment while others negate this approach.

OBJECTIVES

To assess the effects of radioiodine therapy for differentiated thyroid carcinoma with thyroglobulin positive and radioactive iodine negative metastases.

SEARCH STRATEGY

Studies were obtained from computerised searches of MEDLINE, EMBASE, The Cochrane Library, China National Infrastructure (CNKI) and paper collections of conferences held in Chinese.

SELECTION CRITERIA

Randomised controlled clinical trials and prospective controlled clinical trials.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and interviewed authors of all potentially relevant studies by electronic mail to verify randomisation procedures. One author entered data into a data extraction form and the second one verified the results of this procedure.

MAIN RESULTS

Because of the absence of any suitable randomised or prospective controlled trial in this area, results currently cannot be presented.

AUTHORS' CONCLUSIONS

The currently available evidence is insufficient to reliably assess the potential of radioiodine treatment for differentiated thyroid carcinoma with thyroglobulin positive and radioactive iodine negative metastases.

The therapeutic management of differentiated thyroid cancer

BACKGROUND

The management of thyroid cancer is difficult because the tumors comprise a wide range of biologic behaviors, from small papillary thyroid microcarcinomas that pose little or no threat to survival for the patient, to anaplastic thyroid cancers that are arguably the most lethal tumor. Although it may be difficult initially to determine at which end of the prognostic spectrum a patient resides, one can ordinarily estimate a patient's risk for tumor recurrence and mortality based on a triad of features as simple as the patient's age at the time of diagnosis, the tumor stage at presentation, and its initial response to therapy. While staging systems are available to assist in the management process, all are inexact and leave wide gaps in the treatment plan for a given patient. This is largely because randomized controlled trials are lacking as a result of the low incidence and generally favorable prognosis of the disease. As a practical matter, it may sometimes be difficult to reassure a patient, given the generally favorable prognosis of this group of tumors, knowing that without adequate therapy some become unexpectedly aggressive and recur years after initial management. The treatment of these tumors rests on a fine balance of providing care that reflects the anticipated course of the disease without overtreating the patient or providing reassurance that is unfounded.

OBJECTIVE

To outline the treatment strategy for patients with differentiated thyroid cancer based on the available literature and to guide clinicians through a management algorithm utilizing patient and tumor characteristics.

METHODS

This review is limited to the treatment of patients with differentiated thyroid cancer - papillary and follicular thyroid cancer - and the standard therapy required for the majority of patients.

RESULTS/CONCLUSION

The treatment of differentiated thyroid cancer requires a multidisciplinary approach, involving an experienced surgeon, radiologists and an endocrinologist. There are many unanswered questions in the management algorithm and ongoing research is needed to further define the best treatment strategy for patients with differentiated thyroid cancer.

Diagnostic and therapeutic use of recombinant human TSH (rhTSH) in differentiated thyroid cancer

Traditionally, withdrawal of thyroid hormone to increase serum levels of thyroid-stimulating hormone (TSH) has been used in patients with differentiated thyroid carcinoma (DTC) to optimize radio-iodine uptake and serum thyroglobulin (Tg) stimulation during follow-up and in preparation for radio-iodine therapy. However, this procedure is associated with signs and symptoms of hypothyroidism which negatively affect the patient's quality of life. Recombinant human thyrotropin (rhTSH) has provided an effective alternative to thyroid hormone withdrawal. After favourable experimental trials in humans, rhTSH obtained regulatory approval in North America and in Europe as a diagnostic tool, and more recently as a preparation for radio-iodine thyroid remnant ablation. Since then, rhTSH has radically changed the diagnostic and therapeutic management of DTC patients. This review will focus on the clinical application of rhTSH in the management of DTC, highlighting current indications and future perspectives.

Serum thyroglobulin determination in thyroid cancer patients

Serum thyroglobulin determination plays a central role, in combination with neck ultrasonography, in the follow-up of thyroid cancer patients. Its specificity is improved by thyroid remnant ablation, and its sensitivity is optimal following prolonged withdrawal or stimulation with recombinant human thyroid-stimulating hormone (TSH). Modern methods with an improved functional sensitivity may facilitate its use during follow-up.

Radio-iodine therapy in differentiated thyroid cancer: indications and procedures

Post-surgical ablative iodine-131 therapy is recommended for all differentiated thyroid cancer primary tumors>1 cm in diameter. Regarding smaller primary tumors, 131I ablation may be helpful in special cases: tumor close to the thyroid capsule, previous percutaneous radiation to the neck, familial occurrence of thyroid cancer, tumor diameter 5-10 mm, and unfavorable histological variants. In this context, the patient's preferences for safety should be considered. In most centers, standard fixed activities of 1-3 GBq are used for 131I ablation. Preparation for the procedure with such activities requires a low-iodine diet for 2-3 weeks and stimulation of thyroid stimulating hormone (TSH) by withholding of thyroid hormone for 3 weeks following thyroidectomy or by use of recombinant human TSH. The advantages of recombinant TSH are avoidance of hypothyroid morbidity and consequently a better quality of life, as well as a lower radiation dose to extra-thyroidal compartments. To treat metastastic differentiated thyroid cancer, higher activities of radio-iodine (in the range 4-11 GBq) are necessary; if possible, individual dosimetry is recommended. The standard approach to preparation for 131I therapy in patients with metastases is endogenous hypothyroidism after thyroid hormone withdrawal.

Long-term outcome of 495 TNM stage I or II patients with differentiated thyroid carcinoma followed up with neck ultrasonography and thyroglobulin measurements on T4 treatment

OBJECTIVE

Recent guidelines for surveillance of patients with differentiated thyroid carcinoma emphasize TSH-stimulated serum thyroglobulin (Tg) measurements and neck ultrasonographies (US) over Tg measurements on T(4) and diagnostic whole body scans (DxWBS). We evaluated the safety and efficacy of a surveillance paradigm comprising yearly T(4)-suppressed Tg measurements and neck US every second year, with an increase in Tg to a detectable level being a prompt indication for DxWBS.

DESIGN

A retrospective study with a median follow-up of 11.6 years.

PATIENTS AND MEASUREMENTS

Recurrences, cancer-specific deaths and number of neck US, fine needle aspiration biopsies (FNABs) and operations performed were evaluated in 495 low-risk (TNM stage I and II) patients, the majority of whom had total thyroidectomy and radioactive iodine remnant ablation as initial treatment.

RESULTS

Forty-four patients (8.9%) experienced a recurrence in the neck and one patient died. Recurrences were established histopathologically in 26 and by a new uptake in DxWBS in 16 cases. A combination of neck US and high Tg revealed 42 of 44 recurrences. Of 993 ultrasonographies, 149 led to FNAB and 28 FNABs to surgery. Serum Tg was elevated 173 times, indicating a recurrence in 23 patients.

CONCLUSIONS

Although longer follow-up is still needed, monitoring low-risk differentiated thyroid carcinoma patients with neck US and T(4)-suppressed Tg appears to be safe, provided radioactive iodine remnant ablation has been given and a low-alarm threshold for Tg indicating further evaluation, is used. The number of additional studies caused by this surveillance paradigm was reasonable. DxWBS was helpful in selected cases. Comparative studies are warranted to show how much rhTSH-stimulation tests add to this surveillance scheme.

[Follow-up of high-risk patients with differentiated thyroid cancer without persistent disease after initial therapy]

This study evaluated the follow-up of high-risk patients with thyroid cancer after initial therapy. A total of 125 high-risk patients (tumor >4 cm and/or extrathyroid invasion and/or lymph node metastases, and age >45 years), with complete resection of the tumor, were selected. All patients underwent total thyroidectomy and ablation with (131)I[3.7-5.5 GBq (100-150 mCi)]. Eighteen patients (14.8%) presenting metastases on post-dose whole-body scan (RxWBS) were excluded. The negative predictive value of stimulated Tg < or =1 ng/ml in combination with neck US during first assessment (612 mo. after ablative therapy) was 96.2% for the absence of recurrence up to 5 years. This value increased to 98.7% when adding WBS performed with 185 MBq (5 mCi) (131)I (DxWBS). The positive predictive value (PPV) of stimulated Tg >1 ng/ml was 52% for the detection of the presence of metastases up to 5 years; however, considering only patients with initially negative DxWBS and US, the PPV was 19% (9% if Tg of 110 ng/ml vs. 40% if Tg >10 ng/ml). Tg levels decreased spontaneously in patients with stimulated Tg >1 ng/ml during first assessment, negative US and DxWBS, and no recurrence during follow-up, with Tg being undetectable in half these patients at the end of 5 years. Twenty patients presented uptake in the thyroid bed upon DxWBS during the first year after ablative therapy, with stimulated Tg and US being negative, and were not treated with 131I; these patients did not relapse and no uptake on DxWBS was observed in 60% after 5 years. Recurrence after 5 years was only 1.3% in patients without apparent disease (negative US and DxWBS) and stimulated Tg <1 ng/ml. An algorithm for the follow-up of high-risk patients after initial therapy is presented in this study.

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.

How the availability of recombinant human TSH has changed the management of patients who have thyroid cancer

Recombinant human TSH (rhTSH) is used in patients who have had surgery for thyroid cancer but are at low risk of recurrence. The rhTSH is used for the preparation of postoperative administration of 3.7 GBq (100 mCi) of radioiodine for thyroid-remnant ablation and for the determination of serum thyroglobulin levels during follow-up. In these two conditions, the efficiencies of levothyroxine withdrawal and rhTSH administration are similar; however, rhTSH can be administered during levothyroxine treatment, and its use avoids the hypothyroid period induced by levothyroxine withdrawal, reduces whole body exposure after radioiodine administration, avoids potential morbidity and maintains a better quality of life compared with hormone withdrawal.

Comparison of seven serum thyroglobulin assays in the follow-up of papillary and follicular thyroid cancer patients

BACKGROUND

Serum thyroglobulin (Tg) is the marker of differentiated thyroid cancer after initial treatment and TSH stimulation increases its sensitivity for the diagnosis of recurrent disease.

AIM

The goal of the study is to compare the diagnostic values of seven methods for serum Tg measurement for detecting recurrent disease both during L-T4 treatment and after TSH stimulation.

METHODS

Thyroid cancer patients who had no evidence of persistent disease after initial treatment (total thyroidectomy and radioiodine ablation) were studied at 3 months on L-T4 treatment (Tg1) and then at 9-12 months after withdrawal or recombinant human TSH stimulation (Tg2). Sera with anti-Tg antibodies or with an abnormal recovery test result were excluded from Tg analysis with the corresponding assay. The results of serum Tg determination were compared to the clinical status of the patient at the end of follow-up.

RESULTS

Thirty recurrences were detected among 944 patients. A control 131I total body scan had a low sensitivity, a low specificity, and a low clinical impact. Assuming a common cutoff for all Tg assays at 0.9 ng/ml, sensitivity ranged from 19-40% and 68-76% and specificity ranged from 92-97% and 81-91% for Tg 1 and Tg2, respectively. Using assays with a functional sensitivity at 0.2-0.3 ng/ml, sensitivity was 54-63% and specificity was 89% for Tg1. Using the two methods with a lowest functional sensitivity at 0.02 and 0.11 ng/ml resulted in a higher sensitivity for Tg1 (81% and 78%), but at the expense of a loss of specificity (42% and 63%); finally, for these two methods, using an optimized functional sensitivity according to receiver operating characteristic curves at 0.22 and 0.27 ng/ml resulted in a sensitivity at 65% and specificity at 85-87% for Tg1.

CONCLUSION

Using an assay with a lower functional sensitivity may give an earlier indication of the presence of Tg in the serum on L-T4 treatment and may be used to study the trend in serum Tg without performing any TSH stimulation. Serum Tg determination obtained after TSH stimulation still permits a more reliable assessment of cure and patient's reassurance.

Nódulos de tireóide e câncer diferenciado de tireóide: consenso brasileiro

Os nódulos tireoidianos constituem a principal manifestação clínica de uma série de doenças da tireóide com uma prevalência de aproximadamente 10% na população adulta. O maior desafio é excluir o câncer da tireóide, que ocorre em 5 a 10% dos casos. Os carcinomas diferenciados respondem por 90% dos casos de todas as neoplasias malignas da tireóide. A maioria dos pacientes com carcinoma diferenciado apresenta, geralmente, um bom prognóstico quando tratada adequadamente, com índices de mortalidade similares à população geral. No entanto, alguns indivíduos apresentam doença agressiva, desafiando o conhecimento atual e ilustrando a complexidade do manejo dessa neoplasia. No presente trabalho, reunimos 8 membros do Departamento de Tireóide da Sociedade Brasileira de Endocrinologia & Metabologia, para elaborarmos, por consenso, as diretrizes brasileiras no manejo dos nódulos tireoidianos e do câncer diferenciado da tireóide. Os membros participantes representam diferentes Centros Universitários do Brasil, refletindo diferentes abordagens diagnósticas e terapêuticas. Inicialmente, cada participante ficou responsável pela redação de determinado tema a ser enviado ao Coordenador, que, após revisão editorial e elaboração da primeira versão do manuscrito, enviou ao grupo para sugestões e aperfeiçoamentos. Quando concluído, o manuscrito foi novamente enviado e revisado por todos. A elaboração dessas diretrizes foi baseada na experiência dos participantes e revisão pertinente da literatura.

Patients with differentiated thyroid cancer have a venous gradient in thyroglobulin levels

BACKGROUND

Although serum thyroglobulin (Tg) is an excellent marker for detecting recurrent or persistent differentiated thyroid cancer (DTC), it is unreliable in patients who have positive anti-Tg antibodies. Furthermore, a growing number of patients with DTC have elevated Tg levels but no detectable disease on radioiodine scanning or other imaging studies. The objective of this study was to determine whether a gradient in Tg protein level exists in patients with DTC.

METHODS

Fifteen patients who underwent thyroidectomy and/or lymph node dissection for primary DTC (n = 10 patients) and recurrent or persistent DTC (n = 5 patients). A venipuncture was performed simultaneously from the internal jugular vein adjacent to the tumor and the ipsilateral antecubital vein. Venous Tg protein levels were measured by using a chemiluminescence assay. RESULTS.: The average internal jugular-to-antecubital vein Tg protein ratio was 3.4:1.0 (median Tg ratio, 2.9:1; range, 0.8-62.2). Four patients had positive anti-Tg antibodies but still had a Tg gradient. Tg levels were significantly higher in the adjacent internal jugular vein than in the antecubital vein (P = .0019). The Tg ratio between the internal jugular and antecubital veins was significantly higher in patients with recurrent or persistent DTC than in patients with primary tumors (P = .0196).

CONCLUSIONS

To the authors' knowledge, this is the first study to document a venous gradient in Tg protein levels in patients with DTC. The findings suggested that venous sampling for Tg may be used to localize DTC in some patients who have high or increasing serum Tg levels but negative radioiodine scans or imaging studies.

The role of PET in follow-up of patients treated for differentiated epithelial thyroid cancers

This article provides an update on the use of 2-[(18)F]-fluoro-2-deoxyglucose PET in the follow-up of patients treated for differentiated thyroid carcinoma (DTC). Although DTC recurrence is principally identified by a detectable basal or TSH-stimulated thyroglobulin level, PET helps to localize recurrent disease in patients with normal (131)I total-body scans and other normal anatomic imaging studies. The sensitivity of PET for localization of recurrence ranges from 45% to 100% according to tumor burden and differentiation. Whether PET should be performed after TSH stimulation is unclear, but several studies have reported an increase in the number of lesions detected by uptake of 2-[(18)F]-fluoro-2-deoxyglucose in this setting. Dependent on a center's approach, PET can alter therapeutic management in 9-51% of cases. Furthermore, PET might have a prognostic impact on survival in patients with metastatic disease and aid clinicians in selecting patients who need closer follow-up or aggressive treatment. PET can, therefore, be used advantageously in the follow-up of patients with DTC and can localize disease in patients with elevated thyroglobulin levels, normal total-body scans, and normal findings on conventional imaging modalities. In patients in whom local treatment is planned, especially those with aggressive pathologic variants of thyroid cancer, PET can exclude distant metastases. In patients with metastatic disease, PET can help to identify patients needing closer follow-up.

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 outcome of 444 patients with distant metastases from papillary and follicular thyroid carcinoma: benefits and limits of radioiodine therapy

AIM

The goal of this study was to estimate the cumulative activity of (131)I to be administered to patients with distant metastases from thyroid carcinoma.

METHODS

A total of 444 patients were treated from 1953-1994 for distant metastases from papillary and follicular thyroid carcinoma: 223 had lung metastases only, 115 had bone metastases only, 82 had both lung and bone metastases, and 24 had metastases at other sites. Treatment consisted of the administration of 3.7 GBq (100 mCi) (131)I after withdrawal of thyroid hormone treatment, every 3-9 months during the first 2 yr and then once a year until the disappearance of any metastatic uptake. Thyroxine treatment was given at suppressive doses between (131)I treatment courses.

RESULTS

Negative imaging studies (negative total body (131)I scans and conventional radiographs) were attained in 43% of the 295 patients with (131)I uptake; more frequently in those who were younger, had well-differentiated tumors, and had a limited extent of disease. Most negative studies (96%) were obtained after the administration of 3.7-22 GBq (100-600 mCi). Almost half of negative studies were obtained more than 5 yr after the initiation of the treatment of metastases. Among patients who achieved a negative study, only 7% experienced a subsequent tumor recurrence. Overall survival at 10 yr after initiation of (131)I treatment was 92% in patients who achieved a negative study and 19% in those who did not.

CONCLUSION

(131)I treatment is highly effective in younger patients with (131)I uptake and with small metastases. They should be treated until the disappearance of any uptake or until a cumulative activity of 22 GBq has been administered. In the other patients, other treatment modalities should be used when tumor progression has been documented.

Role Of [18F]Fluorodeoxyglucose Positron Emission Tomography In Follow-Up Of Differentiated Thyroid Cancer

OBJECTIVE

To assess the diagnostic utility of [(18)F]flu-orodeoxyglucose positron emission tomography (FDG PET) in the follow-up of patients with differentiated thyroid cancer (DTC).

METHODS

In this study, we used strict definitions of presence and absence of the disease and performed all FDG PET scans while the patients were not taking levothyroxine (LT4). We report the results of conventional FDG PET scans obtained during the follow-up of 50 nonselected patients with DTC (34 female and 16 male patients; median age, 40.5 years; range, 18 to 68). All FDG PET scans and measurement of thyroglobulin (Tg) levels were performed while the patients were not taking LT4 (thyrotropin>or=25 microIU/mL). Tg antibodies were negative in all patients. The initial surgical procedure was total thyroidectomy in all cases, and 26 patients underwent additional operations (2 to 4 procedures). Radioactive iodine (131I) therapy was given to 48 patients (median dose, 5,550 MBq). In 42 patients, FDG PET was used for evaluation of Tg-positive (Tg>2 ng/mL in the absence of LT4 therapy), scan-negative disease. In 8 patients, Tg was <or=2 ng/mL but other findings suggested the presence of the disease (detectable Tg in 7 cases and abnormal ultrasound findings in 3). Disease was considered present if confirmed by fine-needle aspiration, histopathologic examination of subsequent surgical specimens, or persistent elevation of Tg levels (>2 ng/mL without LT4 therapy) for >1 year. Disease was considered absent if Tg was <or=2 ng/mL and at least all the following imaging studies were negative: diagnostic radioiodine whole-body scan, chest radiography or spiral computed tomography of the chest, and high-resolution neck ultrasonography. If all these criteria were present, a positive FDG PET scan was considered a false-positive study.

RESULTS

FDG PET scans were positive in 27 patients (54%) and negative in 23 (46%). FDG PET results were true-positive in 26 cases, false-positive in 1, true-negative in 7, and false-negative in 16. The sensitivity, specificity, and positive and negative predictive values were 61.9%, 87.5%, 96.3%, and 30.4%, respectively.

CONCLUSION

FDG PET scanning is moderately sensitive and specific for detection of persistent or recurrent DTC.

Short-term outcome of differentiated thyroid cancer patients receiving a second iodine-131 therapy on the basis of a detectable serum thyroglobulin level after initial treatment

PURPOSE

The aim of this study was to evaluate the usefulness of high-dose 131I therapy administered only on the basis of raised serum Tg levels.

METHODS

Among patients treated with total or near-total thyroidectomy and 131I ablation, 76 (54 women and 22 men) with differentiated thyroid cancer (41 with follicular and 35 with papillary cancer) showed a detectable (i.e. >1.5 ng/ml) serum Tg level on L: -thyroxine therapy during follow-up and were included in the study. In these patients, a further 131I therapy was scheduled (range 3.7-9.25 GBq, mean 6.087+/-1.705). Five to seven days after this radioiodine therapy, patients underwent 131I post-therapy whole-body scan (131I t-WBS). The serum Tg value at 12 months after 131I therapy was evaluated as an indicator of short-term response to radioiodine.

RESULTS

At evaluation after 12 months, 21 (27.6%) of the 76 patients had a Tg value < or =1.5 ng/ml, 12 (15.8%) showed a Tg decrease of at least 50%, 22 (29%) had only a minor decrease in Tg (<50%) and 21 (27.6%) did not show any decrease in Tg. 131I t-WBS was positive in 52 patients (68%, group A) and negative in 24 (32%, group B). Normalisation of Tg was observed in 15 patients (29%) of group A and in six patients (25%) of group B. Overall, 23 (44%) patients of group A and ten (42%) of group B showed a > or =50% decrease in the Tg. Of the 52 patients of group A, 19 (36%) had local recurrence at 131I t-WBS, 18 (35%) showed lung involvement and 15, (29%) bone metastasis. On a patient basis, two (13%) of 15 patients with bone metastases, six (33%) of 18 patients with lung involvement and seven (37%) of 19 patients with local recurrence had Tg values at follow-up of < or =1.5 ng/ml (p NS). Overall, seven (37%) patients with local recurrence, eight (44%) with lung involvement and eight (53%) with bone metastases showed a > or =50% decrease in Tg.

CONCLUSION

The findings of the present study suggest that the administration of therapeutic 131I only on the basis of elevated Tg levels has a definite therapeutic effect, at least in the short term. In addition, the possibility of obtaining a post-therapeutic 131I WBS can lead to better strategy definition for these patients.

Carcinoma diferenciado de tireóide: avaliação inicial e acompanhamento

O câncer de tireóide é responsável por cerca de 1% dos novos casos de doença maligna diagnosticados. A maioria destes tumores são carcinomas papilares e foliculares, também denominados de carcinomas diferenciados de tireóide (CDT). Estes carcinomas têm uma taxa de cura de aproximadamente 80%, enquanto 20% apresentarão recorrência local e 5 a 10% desenvolverão metástases à distância. Porém, alguns pacientes apresentam uma doença mais agressiva. A identificação de tais pacientes tem grande impacto no manejo clínico do CDT. Várias classificações de estádio clínico e fatores prognósticos são apresentados, bem como os principais exames para seguimento dos pacientes com CDT.

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.

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.

Preoperative neck ultrasonographic mapping for persistent/recurrent papillary thyroid cancer

Surgical resection of persistent/recurrent (P/R) papillary thyroid cancer (PTC), when localized to the neck, is generally recommended; however, its impact on the course of the disease is not clear. We introduced a new technique in the form of preoperative neck ultrasonographic mapping (US-M) to improve the outcome of the surgical resection of P/R PTC. A total of 19 patients had undergone regional (central, lateral, or both) neck dissection before introducing the current technique (group 1, or G1), and 26 patients (group 2, or G2) had limited lymph node resection guided by US-M with findings accurately plotted on a standard diagram. All of the operations were performed by a single surgeon. The surgical outcomes of the two groups were compared. The resected lesions were positive for PTC in 17 patients (89.5%) in G1 and in 25 patients (96.2%) in G2. In G2, the intraoperative findings exactly matched the US-M in 23 patients (88.5%). Postoperatively, neck US became negative in 50% in G1 and in 83.3% in G2 (p = 0.02). Thyroglobulin (Tg) became undetectable in 37.5% in G1 and 52.3% in G2 (p = 0.37). Whole-body iodine scans (WBS) became negative in one of six patients (16.7%) in G1, and in three of four patients (75%) in G2, (p = 0.06). After a mean follow-up of 23.8+/-7.1 months in G1 and 9.8+/-4.7 months in G2, 6 patients (31.6%) in G1 and 15 patients (62.5%) in G2 were in remission (p = 0.04), whereas the disease persisted in 13 cases (68.4%) in G1 and 9 (37.5%) in G2 (p = 0.04). In conclusion, US-M improved the surgical outcome, as evidenced by the postoperative US, Tg, and WBS findings and the higher remission rate for the G2 patients than for the G1 patients.

Long-Term Follow-Up of a Patient With Papillary Thyroid Carcinoma, Elevated Thyroglobulin Levels, and Negative Imaging Studies

OBJECTIVE

To describe a patient with papillary thyroid carcinoma who had measurable thyroglobulin (Tg) levels for 20 years without clinical or imaging evidence of a malignant lesion.

METHODS

We reviewed the clinical course, pathologic findings, Tg measurements, and results of various imaging studies in our patient and reviewed the literature regarding Tg-positive, diagnostic total-body radioiodine scan-negative patients with thyroid cancer.

RESULTS

Four months after a 3.5- by 3.5-cm follicular thyroid cancer was removed from the anterior neck area of a 5-year-old girl, a bilateral subtotal thyroidectomy was performed. At age 12 years, she presented with a 2-cm mass on the right side of the neck. After a completion thyroidectomy, recurrent mixed papillary-follicular thyroid cancer was found scattered throughout the remaining thyroid parenchyma. Although a postoperative diagnostic total-body radioiodine scan did not reveal uptake of (131)I, the Tg level was 58 ng/mL. Despite Tg levels as high as 2,528 ng/mL, the patient had no clinical evidence of thyroid cancer during a 20-year period of follow-up. Moreover, numerous imaging studies, including total-body scanning after the administration of 150 mCi of (131)I and [(18)F]fluorodeoxyglucose positron emission tomography, were negative. Review of pathologic specimens from both operations with use of updated diagnostic criteria indicated that the tumor was a papillary thyroid carcinoma.

CONCLUSION

Our observations and the observations of other investigators indicate that some thyroid cancers produce Tg so efficiently that high levels of Tg may be associated with tumors that remain too small to be detected by imaging studies. The Tg levels may remain stable, decline, or even disappear over time without treatment.

Manifestações clínicas e diagnóstico de metástases distantes de carcinoma diferenciado de tireóide após a terapia inicial

Avaliamos 58 pacientes com metástases distantes de carcinoma de tireóide diagnosticadas após a terapia inicial. Metástases linfonodais na apresentação inicial foram verificadas em 65%. Todas as metástases linfonodais, 90% das pulmonares e apenas 25% das metástases ósseas eram assintomáticas. Radiografia revelou metástases líticas em todos os casos com acometimento ósseo; foi normal em 39,6%, mostrou micrometástases em 34,5% e macrometástases em 25,8% nos pacientes com doença pulmonar. A tireoglobulina (Tg) em uso de tiroxina foi detectável (> 1ng/ml) em todos sem anticorpos anti-tireoglobulina (TgAb), > 5ng/ml em 90% e > 10ng/ml em 80% e, após a suspensão da terapia, > 5ng/ml em 100% e > 10ng/ml em 94%. Nos pacientes com TgAb (13,8%), Tg foi indetectável em metade. Varredura diagnóstica com 5mCi de iodo 131 foi positiva em 83% e 77,6% dos pacientes com metástases ósseas e pulmonares, respectivamente e após dose ablativa, a sensibilidade foi de 100 e 93%. Dos pacientes com varredura diagnóstica negativa, 85% tinham metástases pulmonares visíveis na radiografia. Concluímos que a Tg é o método mais sensível, seguro e de menor custo no seguimento de câncer diferenciado de tireóide, e reforçamos a administração direta de uma dose ablativa de radioiodo com realização de varredura pós-dose quando a Tg estiver elevada.

Factors influencing the basal and recombinant human thyrotropin-stimulated serum thyroglobulin in patients with metastatic thyroid carcinoma

The serum thyroglobulin (Tg) level is the most sensitive marker for detecting residual thyroid carcinoma. We hypothesized that the basal and TSH-stimulated Tg levels in patients with metastatic thyroid carcinoma would reflect tumor volume, histological subtype, and location of metastatic lesions. A retrospective review of 417 thyroid cancer survivors undergoing evaluation for residual disease with the assistance of recombinant human TSH (rhTSH) was performed. In 169 patients with metastatic disease, we found that the basal Tg level directly correlated with the number of lesions, and that it was highest in patients with follicular and lowest in those with papillary thyroid carcinoma. The basal Tg level was highest in patients with bone metastases and lowest in those with cervical metastases. The fold increase in the serum Tg after rhTSH treatment was highest in papillary thyroid carcinoma and lowest in Hurthle cell carcinoma. The fold increase in Tg was not influenced by tumor volume or by the site of metastatic lesions. Multivariate analysis showed multiple interactions between factors, but did not identify one factor that significantly influenced basal Tg or fold increase. We conclude that the location and volume of metastases influence basal Tg, but not its responsiveness to rhTSH, whereas the histological type of carcinoma influences both basal Tg and responsiveness to rhTSH.

Diagnostic I–131 scintigraphy in patients with differentiated thyroid cancer: No additional value of higher scan dose

OBJECTIVE

After initial treatment with total thyroidectomy and radioiodine ablation, most follow-up protocols for patients with differentiated thyroid carcinoma contain cyclic diagnostic I-131 imaging and serum thyroglobulin measurements. The applied diagnostic I-131 doses vary between 37 and 370 MBq. The aim of this study was to determine the yield of a diagnostic scan with 370 MBq I-131 in patients with a negative diagnostic scan with 74 MBq I-131.

METHODS

Retrospective evaluation of 158 patients who received a high-dose diagnostic scan with 370 MBq I-131 because of a negative low-dose diagnostic scan with 74 MBq I-131. Special attention was paid to the patients with positive high-dose diagnostic scanning and undetectable serum thyroglobulin levels after thyroid hormone withdrawal.

RESULTS

In 127 (80%) of patients the 370 MBq I-131 scan was negative, just like the preceding low-dose scan. In 31 (20%) of patients abnormal uptake was present on the 370 MBq diagnostic scan. In 19 of these 31 patients serum thyroglobulin was undetectable. In 15/19 the high-dose diagnostic scan proved either false positive or demonstrated clinically irrelevant minor ablation rests. In only four patients (2.5%) did the high-dose diagnostic scans reveal possibly relevant uptake caused by residual differentiated thyroid cancer.

CONCLUSION

In 98% of patients a 370 MBq dose of I-131 for diagnostic WBS had no additional value. The combination of a low-dose diagnostic I-131 scan using only 74 MBq combined with a serum Tg level measurement proved sufficient for correct clinical decision making regarding whether the patient requires additional I-131 therapy.

Current Strategies for Surgical Management and Adjuvant Treatment of Childhood Papillary Thyroid Carcinoma

Childhood papillary thyroid carcinoma is associated with more locally aggressive and more frequent distant disease than its adult counterpart. Recurrence rates tend to be higher in children, but cause-specific mortality remains low. Optimal initial treatment of childhood papillary thyroid carcinoma should include total or near-total thyroidectomy and central compartment node clearance. Modified neck dissections should be performed for biopsy-proven lateral neck disease. Every effort should be made to maintain parathyroid and laryngeal nerve function. Radical neck dissections are to be avoided. Radioiodine remnant ablation (RRA), appropriate thyroid hormone suppressive therapy (THST), and judicious use of therapeutic doses of (131)I are applied to achieve a disease-free status, which is most often confirmed by negative neck ultrasonography, negative whole-body scan (either withdrawal or recombinant human thyroid-stimulating hormone-stimulated), and extremely low levels of serum thyroglobulin. Appropriate utilization of (131)I, THST, repeat surgery, external beam radiotherapy, and rarely chemotherapy may provide long-term palliation and some cures in patients with recurrent/persistent disease. Follow-up should be lifelong, and the care of children after age 17 should subsequently be transferred to adult-care endocrinologists with expertise in managing thyroid neoplasia. Optimal surgical management can be achieved if adequate operations are routinely carried out by "high-volume" thyroid surgeons with expertise in the care of children. Nowhere is a multidisciplinary approach (endocrinologists, surgeons, nuclear medicine physicians, pediatricians, pathologists, oncologists) more critical than in the long-term management of papillary thyroid carcinoma that presents during childhood.

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.

Treatment of iodine-negative thyroglobulin-positive thyroid cancer: differences in outcome in patients with macrometastases and patients with micrometastases

PURPOSE

During the follow-up of patients with well-differentiated thyroid carcinoma, some patients have elevated serum thyroglobulin (Tg) levels without any evidence of radioiodine accumulation on diagnostic whole-body scan (d-WBS). The treatment strategy in these patients is considered a clinical dilemma, with some groups recommending blind use of high-dose radioiodine therapy. The aim of this study was to evaluate whether or not high doses of radioiodine have beneficial effects in these patients.

METHODS

Twenty-seven patients were included in the study. All patients had negative d-WBS and elevated levels of Tg. All received high doses of radioiodine. The mean follow-up period was 6.3+/-5.8 years. There were 11 patients with macrometastases and 16 with micrometastases.

RESULTS

Post-treatment WBS revealed radioiodine accumulation in 19 of 24 (79%) patients. Serum Tg levels were decreased in 8 of 16 (50%) patients. Among patients with micrometastases, five out of seven (71%) demonstrated a decrease in serum Tg levels. Among patients with macrometastases, three out of nine (33%) demonstrated a decrease in Tg values and three (33%) have died due to metastatic thyroid cancer.

CONCLUSION

Radioiodine treatment may have a beneficial therapeutic effect in patients who have elevated levels of serum Tg and negative d-WBS. This is especially true in those patients with micrometastases; in patients with macrometastases, a beneficial effect of this approach may be observed less frequently.

Failure to use measurement of megalin secretory components complexed with serum thyroglobulin as a tool to identify metastases after surgery in papillary thyroid cancer

When thyroid follicles are intact, some colloidal thyroglobulin (Tg) reaches the circulation by megalin-mediated transcytosis and is to various extents complexed with megalin secretory components. In contrast, in papillary thyroid cancer (PTC), serum Tg is not complexed with megalin because it is directly secreted by tumor cells. Here we attempted to use measurement of megalin secretory components to distinguish PTC patients with thyroid remnant plus metastases from those with thyroid remnant only, after thyroidectomy and before 131I ablation. Tg values in anti-Tg antibodies (TgAb)-free sera from 5 PTC patients with thyroid remnant plus metastases and 12 PTC patients with thyroid remnant only were measured following pre-adsorption with uncoupled protein A beads or with protein A beads coupled with antimegalin antibodies. The degree of Tg pre-adsorption with antimegalin antibodies was minimal, with no substantial differences between the two groups. Thus, we concluded that measurement of megalin secretory components is unlikely to be useful to identify the origin of serum Tg in PTC patients after thyroidectomy.