Management of patients with differentiated thyroid cancer who have positive serum thyroglobulin levels and negative radioiodine scans

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.

Utility of serum thyroglobulin measurements after prophylactic thyroidectomy in patients with hereditary medullary thyroid cancer

INTRODUCTION

Prophylactic thyroidectomy can be curative for patients with hereditary medullary thyroid cancer (MTC) caused by RET proto-oncogene mutations. Calcitonin is a sensitive tumor marker used to follow patients. We suggest that thyroglobulin (Tg) levels should also be monitored postoperatively in these patients.

METHODS

We reviewed patients with RET mutations who underwent prophylactic thyroidectomy between 1981 and 2011 at an academic endocrine surgery center. Patients were excluded if they had no postoperative Tg levels recorded.

RESULTS

Of the 22 patients who underwent prophylactic thyroidectomy, 14 were included in the final analysis. The average age at thyroidectomy was 9.8 years (range, 4-29). Tg levels were detectable 1.5 months to 31 years postoperatively in 11 patients (79%), all of whom were <15 years old at thyroidectomy. Median thyroid-stimulating hormone (TSH) was 2.5 mIU/L and 13.4 mIU/L in patients with undetectable and detectable Tg, respectively. Of those with detectable Tg, 5 had cervical ultrasonographic examination: Two showed no residual tissue in the thyroid bed, and 3 showed remnant thyroid tissue.

CONCLUSION

Tg levels can identify patients with remnant thyroid tissue after prophylactic thyroidectomy. Ultrasonography can determine whether thyroid tissue remains posterolaterally that is at risk of MTC recurrence. Maintaining normal TSH may prevent growth of remaining thyroid follicular cells.

Role of [(18)F]-fluorodeoxy-D-glucose positron emission tomography and computed tomography in the early detection of persistent/recurrent thyroid carcinoma in intermediate-to-high risk patients following initial radioactive iodine ablation therapy

BACKGROUND

Positron emission tomography/computed tomography (PET/CT) scan has a role in the surveillance of patients with a history of thyroid carcinoma. Its efficacy after remnant ablation as far as detecting persistent or recurrent thyroid carcinoma before other surveillance methods is not known, however. In intermediate-to-high risk thyroid carcinoma patients we studied whether PET/CT scan, performed 6-12 months after the first remnant ablation, could provide more information than ultrasonography (US) and thyrotropin-stimulated serum thyroglobulin (Tg) determination with diagnostic whole-body scan (DxWBS).

METHODS

We studied 71 subjects with differentiated thyroid cancer (DTC) who were intermediate-to-high risk for persistent/recurrent disease and who had received PET/CT scan, US, and DxWBS simultaneously with stimulated Tg levels 6-12 months after remnant ablation. To evaluate the diagnostic efficacy of PET/CT scan, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were calculated.

RESULTS

Ten subjects (14%) had persistent/recurrent disease detected 6-12 months after remnant ablation. Persistence/recurrence was detected in nine (12.7%) of these patients by conventional methods, including US and DxWBS, along with stimulated Tg levels. The remaining case was detected solely by a PET/CT scan, which showed a mediastinal prevascular lesion; this was confirmed by a therapeutic WBS after additional radioiodine therapy. Among the six patients whose PET/CT scan showed positive results, five had persistent/recurrent disease. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of PET/CT scan for detecting persistent/recurrent thyroid carcinoma were 50%, 98.4%, 83.3%, 92.3%, and 91.5%, respectively.

CONCLUSION

In intermediate-to-high risk patients with DTC seen 6-12 months after their first remnant ablation, there is almost no complementary role for adding a PET/CT scan to conventional follow-up methods, an US and a DxWBS simultaneously with stimulated Tg levels.

Management of thyroid cancers

Thyroid cancers cover a large spectrum of disease with diametrically opposite prognosis. At one end of the spectrum we have the well differentiated cancers which carry an excellent prognosis, while at the other end there is anaplastic cancer with high mortality rates and dismal prognosis. Management of thyroid cancers still has some controversial issues due to lack of randomized controlled trials. Extent of surgery, extent of neck dissection, role of radioiodine treatment and thyroid stimulating hormone suppression are still debatable. In this review, we highlight these controversial issues and give guidelines for the management and follow up of patients with thyroid cancer.

Postoperative management of thyroid carcinoma

Survival from differentiated thyroid carcinoma is generally good, but postoperative management plays an important role in minimizing the likelihood of disease recurrence. Postoperative management is generally performed by endocrinologists and nuclear medicine physicians, who exploit thyroid cells' inherent iodineavidity and sensitivity to hormonal manipulation in a unique cancer management paradigm. Endocrinologists manage thyroid hormone replacement/thyroid stimulating hormone suppression and coordinate surveillance. Nuclear physicians administer targeted therapy with radioactive iodine and perform imaging studies to assess disease status. This article provides an overview of the postoperative assessment, treatment, and follow-up of patients who have thyroid carcinoma.

The Role of Positron Emission Tomography Scanning in Patients with Radioactive Iodine Scan-Negative, Recurrent Differentiated Thyroid Cancer

An elevated thyroglobulin (Tg) level after total thyroidectomy for differentiated thyroid cancer is often associated with disease recurrence. 131I-whole body scans (131I-WBS) and cross-sectional imaging are commonly used to localize occult metastases in these patients. Localizing disease when 131I-WBS are negative and cross-section imaging is equivocal remains a challenge. The medical records of 12 patients with thyroid cancer undergoing positive positron emission tomography (PET) scans for 131I-WBS-negativeTg elevations or the presence of anti-Tg antibodies were identified and charts were reviewed in a retrospective fashion. All had been treated with total thyroidectomy and 131I ablation in the past. Computed tomography, magnetic resonance imaging, or ultrasound studies revealed suspicious lesions in eight patients. All 12 patients underwent resection of the PET-positive lesions. All resections were positive for thyroid cancer in the regions predicted by the positive PET scan. All nine (100%) patients with elevated preoperative Tg levels experienced a reduction in Tg level after resection. PET scans accurately predict the presence of recurrent thyroid cancer when 131I-WBS are negative. PET scans should be considered in the follow up of 131I-WBS-negative patients with thyroid cancer who are suspected of having recurrent disease.

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.

Changing Concepts in the Management of Differentiated Thyroid Cancer

The management of patients with differentiated thyroid cancer has changed significantly over the last few decades. Mortality has decreased as the result of earlier detection, refined surgical approaches, subsequent radioiodine ablation, and the development of more sensitive methods for detecting and monitoring disease recurrence. The latter has been facilitated by serum thyroglobulin measurements, the use of recombinant human thyrotropin, and the use of 18F-deoxyglucose/positron emission tomography in selected instances where radioiodine imaging fails to locate known or suspected recurrent or metastatic disease.

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.

The Role of Positron Emission Tomography/Computed Tomography in the Management of Recurrent Papillary Thyroid Carcinoma

OBJECTIVES/HYPOTHESIS

The aim of the study was to evaluate the role of combined positron emission tomography/computed tomography (PET/CT) fusion imaging in the detection and management of recurrent papillary thyroid cancer.

STUDY DESIGN

A retrospective analysis of 33 patients with suspected recurrent papillary thyroid carcinoma who had undergone PET/CT was performed. PET/CT was compared with standard imaging techniques in each patient to determine whether PET/CT contributed to the therapeutic management plan. Histopathological findings were correlated to PET/CT in patients who underwent surgery.

METHODS

The senior author reviewed the charts of 33 patients with recurrent papillary thyroid carcinoma to determine the impact PET/CT had on management. PET/CT was compared with conventional imaging results. In surgical patients, PET/CT was compared with histopathological findings to determine its sensitivity, specificity, accuracy, positive predictive value, and negative predictive value.

RESULTS

In 67% of the cases (22 of 33), PET/CT supplied additional information that altered or confirmed the management plan. Twenty of 33 patients underwent surgery with 36 sites assessed by histopathological analysis. PET/CT correlated with histopathological findings in 25 of 36 distinct anatomical sites, with an accuracy of 70%. The sensitivity of PET/CT in identifying recurrence was found to be 66%, with a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 27%.

CONCLUSION

Combined PET/CT fusion scanning was most useful in the detection and management of recurrent papillary thyroid cancer in patients who had average thyroglobulin levels greater than 10 ng/mL and when the tumor no longer concentrated radioactive iodine. In 100% of the cases in which PET/CT localized a region suspicious for malignancy, histopathological analysis confirmed the results. When PET/CT is positive, it is a powerful tool for predicting exact locations of recurrent papillary thyroid cancer, thus making it a reliable guide for surgical planning. PET/CT is a supplement to conventional imaging and fine-needle aspiration in the workup of recurrent papillary thyroid cancer. A negative finding on PET/CT is not sufficiently reliable to preclude further investigation and treatment.

Role of131I in the treatment of well differentiated thyroid cancer

(131)I is an integral component in postsurgical management of well-differentiated thyroid cancer (WDTC), which includes papillary and follicular types. (131)I is used postsurgically to either destroy remaining thyroid tissue (thyroid ablation) or to treat recurrence and metastases (radioiodine therapy). (131)I is no longer a routine diagnostic modality, but it is widely used for remnant ablation after thyroidectomy for WDTC > 1 cm, under conditions of thyroxine withdrawal. It is generally-though not unanimously-accepted that postsurgical radioiodine is the most powerful method by which to lengthen disease-free survival. (131)I cannot be used if the residual thyroid remnant is large; many surgeons therefore perform near-total or total thyroidectomy for all WDTC > 1 cm. Since 1997, radioiodine treatment has been performed in outpatient settings, where side effects are common, but mild and transient. Secondary screening is by physical exam, thyroglobulin measurements, and (131)I diagnostic whole-body scans. This is performed under conditions of thyrotropin stimulation, which is accomplished either by thyroxine withdrawal or administration of recombinant human thyrotropin. While most cancers are well treated with radioiodine, some advanced cancers may no longer take up radioiodine, rendering them resistant to treatment. For these cancers, redifferentiation therapy and molecular target-specific medicines hold future promise for improved treatment.

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.

Surgical therapy of the thyroid papillary carcinoma in children: experience with 56 patients < or =16 years old

BACKGROUND/PURPOSE

This article is an anatomic, clinical, therapeutic, and prognostic assessment of 56 children 16 years of age or younger, who underwent a surgical operation for thyroid papillary carcinoma from April 1988 to December 2001 in the Department of General Surgery at the University of Pisa. Of these 56 patients, 22 are Belarus children (39%) in whom carcinoma developed after the nuclear accident in Chernobyl in April 1986, whereas 34 (61%) are children with differentiated nonirradiated tumors. The purpose of this work was to compare the group of children who had radiation-induced thyroid carcinoma with the group affected by non-radiation-induced carcinoma to evaluate if there are significant clinical, anatomic, and prognostic differences between them and to identify the best surgical strategy to adopt.

RESULTS

At the time of clinical presentation, the tumor was limited to the thyroid gland in 28 cases (50%), whereas in the others, in 24 cases (43%) metastases in the neck lymph nodes were present or had infiltrated the extrathyroid tissues as was seen in 4 cases (7%). The surgical operation was a total thyroidectomy in 37 cases (66%), whereas in 19 patients with radiation-induced carcinoma it was a hemithyroidectomy followed by a completion of thyroidectomy in Pisa (34%). The histologic examination showed multifocal sites of papillary adenocarcinoma in the gland in 23% of cases, and both lobes of the thyroid gland were involved with tumor in 23% of patients. The postsurgical follow-up showed a mortality rate of 0% and a recurrence rate of 33.5% (64% radiation-induced carcinoma v 3% non-radiation-induced carcinoma; P < .0001). At the moment, 8 of 22 cases (36%) with radiation-induced carcinoma are free of disease versus 33 of 34 (97%) with non-radiation-induced carcinoma (P < .0001).

CONCLUSIONS

These findings show carcinoma of the thyroid in children has a low risk of mortality but a high risk of recurrence. Children with radiation-induced thyroid carcinoma are more likely to have a recurrence of the disease. Total thyroidectomy for the treatment of both radiation-induced and non-radiation-induced carcinomas appears to represent, on the basis of these results, the best therapeutic option.

Thyroglobulin monitoring after treatment of well-differentiated thyroid cancer

AIMS

The prognosis for well-differentiated thyroid carcinomas is favourable after treatment, but the rate of recurrence is around 20%. Cervical ultrasonography, radio-iodine scans, and monitoring of serum thyroglobulin (Tg) levels allow these recurrences to be diagnosed. The management of patients with isolated elevated Tg levels is controversial in the presence of negative radio-iodine scans.

METHODS

The records of 57 patients diagnosed with recurrence of well-differentiated thyroid cancer were reviewed. Serum Tg was not evaluated in 31 of these patients (group 1) and measured in the other 26 cases (group 2).

RESULTS

Forty-three recurrence sites were found; four deposits in the thyroid bed and 39 cervical metastatic nodes, with an average of five nodes per patient. The radio-iodine scan was accurate in detecting 10/24 of cases, radiology in 9/17, and elevated Tg levels in 20/25. Thirteen patients with recurrences diagnosed on the basis of Tg levels had negative radio-iodine scans. After surgery, Tg levels were normal in 10 patients from group 1 and 16 patients from group 2 (p=0.0078).

CONCLUSIONS

Elevated Tg levels are indicative of disease progression or recurrence in patients who have previously been operated on for well-differentiated thyroid cancer. Even when the radiological study or radio-iodine scan is normal, surgical re-exploration of the neck, with total thyroidectomy and lymphadenectomy, is advisable.

Current controversies in the management of pediatric patients with well-differentiated nonmedullary thyroid cancer: a review

Current treatment strategies for pediatric patients with nonmedullary, well-differentiated thyroid carcinoma (WDTC) are derived from single-institution clinical cohorts, reports of extensive personal experience, and extrapolation of several common therapeutic practices for this tumor in adults. Because pediatric WDTC is an uncommon malignancy, the issues of its optimal initial and subsequent long-term treatment and follow-up remain controversial. Pediatric patients with WDTC can be divided into two groups: children younger than 10 years of age and teenagers/adolescents between 10 and 18 years of age because these groups have different recurrence and mortality rates. We hereby present our views and interpret them in the light of the pertinent literature. Our recommendations on treatment strategies are more relevant for younger children. After midpuberty, optimal treatment is adequately addressed in the relevant literature on adults. For the majority of patients, total/near-total thyroidectomy is currently recommended as the standard initial therapy for WDTC. This is commonly followed by administration of radioiodine (RAI; (131)I) therapy to destroy residual normal thyroid tissue (remnant). Routine (131)I remnant ablation has been shown to: (1). decrease the risk of local recurrences, (2) increase the sensitivity of subsequent diagnostic RAI whole-body scanning (WBS), and (3) render serum thyroglobulin (Tg) a highly sensitive marker for recurrent/residual disease during long-term follow-up. We recognize that the above practices are not universally adhered to in children and adolescents, because the risk stratification and intensity of applied therapeutic measures are influenced by institutional traditions and personal experience. In our view, aggressive initial management, followed by evaluations at regular intervals after thyroidectomy and (131)I remnant ablation, in conjunction with long-term thyroid hormone suppressive therapy (THST), result in decreased recurrence rates in pediatric patients with WDTC. Follow-up examinations should include a diagnostic RAI ((131)I or (123)I) WBS and measurement of serum Tg, both performed under conditions of TSH stimulation, as well as neck ultrasonography (US). Our strategy is corroborated by data from retrospective clinical cohort studies. In this malignancy, no evidence of disease (NED) status can be defined as the combination of a negative diagnostic WBS and the presence of undetectable or low serum Tg levels, both tested under TSH stimulation. These findings should be accompanied by the absence of anatomically definable disease by standard imaging modalities, e.g., neck US or chest computed tomography (CT). Although the long-term survival rates are good overall in this disease, selected patients may require further surgery or (131)I therapy for the eradication or clinical control of metastases. Finally, and importantly, because the duration of follow-up is lifelong, the care of children with prior diagnosis of WDTC should be transferred to an adult endocrinologist after they reach adulthood, even if they have achieved NED status by that time.

Impact of cervical lymph node dissection on serum TG and the course of disease in TG-positive, radioactive iodine whole body scan-negative recurrent/persistent papillary thyroid cancer

In the management of papillary thyroid cancer (PTC), surgery is indicated for locoregional recurrent/persistent disease. In this study, we examined the effect of such surgery on serum TG and the course of the disease in 21 patients with PTC (mean age 38.5 yr), who after the initial surgery and radioactive iodine (RAI) ablation developed high TG (>10 ng/ml) and negative 123I whole body scan (DxWBS). All patients had neck persistent/recurrent PTC that was confirmed by ultrasound-guided fine needle aspiration. Prior to neck re-exploration, radiological studies (chest X-rays, CT scan of the chest, and fluoro-18-deoxyglucose positron emission tomography [FDG-PET]) showed no evidence of distant metastases. TG autoantibodies were negative in 19 patients. Second surgery consisted of unilateral (13 patients) or bilateral (8 patients) modified neck dissection. The mean+/-SE TG prior to neck re-exploration was 184.8+/-79.0 ng/ml and declined after surgery to 127.5+/-59.0 ng/ml (p=0.25). The corresponding TSH values were 150.6+/-23.0 and 143.4+/-20.0 mU/l, respectively (p=0.34). After a mean follow-up of 20.7+/-3 months, TG increased to 168+/-68.0 ng/ml. This increase, however, was NS (p=0.67). The corresponding TSH values were 143.4+/-20.0 and 132.0+/-22.0 mU/l (p=0.27). Following second surgery, only 4 patients achieved remission, the other 17 patients received one or more of the following therapies; RAI (10 patients), third surgery (5 patients), and/or external radiation (7 patients). Thirteen patients continued to have persistent disease and 4 patients showed progressive course of their disease (distant metastases or grossly palpable neck disease). In conclusion, second surgery for recurrent/persistent PTC leads to remission in only a minority of cases but the course of the disease tends to be stable in most cases.

Lack of impact of radioiodine therapy in tg-positive, diagnostic whole-body scan-negative patients with follicular cell-derived thyroid cancer

Several reports have suggested a benefit from radioactive iodine (RAI) therapy in Tg-positive, whole-body scan-negative patients with follicular cell-derived thyroid cancer, who were said to have high rates of visualization of uptake in metastases after therapeutic doses of RAI. We sought to evaluate the rate of visualization of RAI uptake in these patients and determine the effect of such therapy on tumor progression and Tg levels. We studied 24 consecutive patients who had been treated with high-dose RAI, four of whom had no evidence of metastasis or persistent cancer. Our results showed that four patients had some uptake in posttherapy scans: in the neck, lung, and mediastinal metastases in one patient, in the thyroid remnant in two, and in a possible neck microrecurrence in one. In 13 patients with macrometastases-tumors 1 cm or greater-tumors progressed and serum Tg increased; five have died of thyroid cancer. The disease remained stable in the seven patients with micrometastases. We concluded that in high-risk patients with follicular cell-derived thyroid cancer with high Tg levels and negative diagnostic whole-body scans, only a small number showed meaningful uptake after high doses of RAI. Therefore, widespread use of empiric RAI therapy for such patients who have a large tumor burden should not be encouraged.

[Locoregional recurrence of differentiated thyroid cancers: diagnosis-treatment]

AIM OF THE STUDY

To evaluate the improvement of the diagnosis and the treatment of local recurrences (LR) in patients with differentiated thyroid carcinoma.

MATERIAL AND METHOD

Among a total of 57 patients, two groups were compared: group I: 31 patients operated on from 1974 to 1990; group II: 26 patients operated on from 1991 to 2000. In the group I, the diagnosis of the cervical recurrence was supported by imaging study (ultrasonography, tomodensitometry), in the group II by radioiodinescan and serum thyroglobuline (Tg) measurement. The main difference was the consideration of Tg measurement to detect the recurrence in the group II. A high level of Tg was the only abnormality for 9 patients of the group II.

RESULTS

A nodal recurrence was respectively present in the group I and II in 88.8% and 92% of the cases. Re-operation consisting in thyroid totalisation and bilateral lymphadenectomy was respectively performed in 71% and 100% of the cases. Surgery associated with iodine 131 therapy was respectively the treatment for 45.1% and 88.4% of the cases. After a median follow up of 66.2 months; results of the group I were as follow: normal or undetectable Tg: 10 (33.3%), second or more cervical recurrences: 7, distant metastases: 11, death in relation to thyroid cancer: 11. After a median follow up of 36.3 months, results of the group II were as follow: normal or undetectable Tg: 17 (65.4%), second or more cervical recurrences: 6, distant metastasis: 5, death in relation to thyroid cancer: 1. The best results concerned patients with an isolated elevated Tg without anatomical location of the first LR.

CONCLUSION

LR diagnosis is difficult and needs imaging study, radioiodine-scan and serum Tg determination together. Re-operation associated with radioiodine-therapy is the treatment of choice. Elevated serum Tg is suffisant to indicate re-operation even if no anatomical substrate is found. Iodine-radiotherapy alone is generally unable to obtain undetectable serum Tg.

Isotope imaging for metastatic thyroid cancer

Many isotopes are available for imaging patients with suspected thyroid cancer recurrence and metastases. TSH-stimulated low-dose 131I whole-body scanning with serum thyroglobulin either by standard LT4 withdrawal or rhTSH stimulation is the preferred test for monitoring patients without palpable disease or elevated serum thyroglobulin on LT4 therapy (Fig. 5). This approach has the advantage of finding disease that may be amenable to 131I therapy, although low-dose 131I scans are less sensitive than are scans with other imaging agents. 123I has better imaging characteristics than 131I and has been shown to be equivalent or superior to low-dose 131I in recent studies. As the availability of 123I increases and the cost decreases, this agent may replace 131I in imaging for recurrent or metastatic thyroid cancer. Patients who have an elevated serum thyroglobulin on LT4 therapy or after TSH stimulation but have a negative low-dose 131I scan require other imaging procedures to find the suspected disease. The authors currently perform a sensitive neck ultrasound to look for surgically remediable disease and consider a noncontrast CT scan of the chest to look for small pulmonary metastases that poorly concentrate low doses of 131I (Fig. 5). Fluoro-18-deoxyglucose PET, 99mTc MIBI, 201Tl, and 99mTc tetrofosmin are primarily useful in the setting of a negative whole-body 131I scan and elevated serum thyroglobulin. 18FDG-PET seems to have the highest sensitivity in this setting and would be the preferred imaging agent, but availability and cost are major issues (Fig. 5). Although some researchers have advocated these radiopharmaceuticals as first-line agents replacing 131I, there is little support for this position. This approach to imaging is not cost-effective because positive scans in these patients would most likely require 131I scintigraphy to determine whether the lesions are amenable to radioiodine therapy. 99mTc pertechnetate, 99mTc furifosmin, and somatostatin receptor scintigraphy have a limited role in imaging for recurrent or metastatic differentiated thyroid carcinoma. In choosing among 99mTc MIBI, 201Tl, and 99mTc tetrofosmin, the technetium label of sestamibi and tetrofosmin results in better image quality and faster imaging than 201Tl. Although 99mTc sestamibi and 99mTc tetrofosmin have not been compared in a large series, the higher tumor-to-background ratio and consistently high sensitivities of 99mTc tetrofosmin suggest that it could potentially have additional value over 99mTc sestamibi, but there is still limited experience with 99mTc tetrofosmin.

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.

Value of preoperative diagnostic modalities in patients with recurrent thyroid carcinoma

BACKGROUND

Patients with well-differentiated thyroid cancer (WDTC) regularly have an excellent prognosis. However, tumor recurrence either involving the thyroid bed or the regional lymph nodes, or both, can be associated with significant morbidity and even mortality. The aim of the follow-up after primary surgery is to detect recurrent disease at its earliest stage. We assessed the value of different diagnostic methods in detecting locoregional recurrence in patients with WDTC.

METHODS

We prospectively identified 150 patients with WDTC. Of those, 43 (28.7%) presented with recurrent disease. Ultrasonography-guided fine needle biopsy (US-FNB), iodine 131 ((131)I) wholebody scintigraphy, thyroglobulin (Tg) measurement, and fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) were carried out.

RESULTS

Ultrasonography detected malignant lesions in 95.3% of the patients. The true positive rate of US-FNB was 95.3%. (131)I scanning had true positive, false negative, and false positive results in 54.2%, 40.0%, and 5.7% of the cases, respectively. In 85.7% of the patients, Tg levels were within pathologic range. Among the 13 patients who underwent FDG-PET, 84.6% showed pathologic uptake indicating malignancy. US and US-FNB provided the highest specificity for detecting recurrence (P <.001).

CONCLUSIONS

In patients with WDTC and locoregional recurrence, US and US-FNB are the most sensitive methods in detecting local recurrence or regional lymph node metastases. FDG-PET is valuable in case of negative (131)I scanning results and elevated serum Tg levels. The method has limitations in finding minimal disease.

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.

Treating the patient with differentiated thyroid cancer with thyroglobulin-positive iodine-131 diagnostic scan-negative metastases: including comments on the role of serum thyroglobulin monitoring in tumor surveillance

Differentiated thyroid cancer (DTC) patients, especially the 10% to 15% at high risk of cancer-related death, should have long-term monitoring for detection of recurrence or metastasis. Conventional radiologic and ultrasonographic imaging is useful for localization of recurrent or persistent disease. For patients who have had ablation of residual thyroid tissue, measurement of serum thyroglobulin (Tg) levels and radioactive iodine (RAI) imaging provide highly sensitive tools for early detection. Serum Tg is reliable only in the absence of Tg autoantibodies. Sensitivity increases with TSH stimulation, either by withdrawal of thyroxine (T4) therapy, or administration of recombinant TSH (rTSH). In some patients, serum Tg levels are positive but the RAI whole body scan (WBS) is negative. In these patients, either the recurrent tumor is too small and below the sensitivity of the diagnostic scan, or there is a dissociation between Tg synthesis and the iodine-trapping mechanism. Recent literature suggests that empiric high-dose RAI therapy of Tg-positive diagnostic scan-negative patients may result in a high rate of visualization of uptake in posttherapy scans (PTS). Evidence for subsequent improvement of parameters of disease activity has also been presented. Almost all such reported cases had micrometastases that were not visualized by conventional imaging. In our experience, aggressive macrometastases with negative diagnostic WBS do not show significant uptake after therapeutic doses of RAI. The small size of micrometastases in the first group of patients and a possible defect of the iodine-trapping mechanism in the second group may explain this apparent discrepancy. Based on presently available information, a generalized recommendation for RAI therapy of Tg-positive, diagnostic scan-negative patients should await further studies. Meanwhile, in some high-risk patients, in the absence of alternative therapies, empiric RAI therapy is justified.

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.

Value of stimulated serum thyroglobulin levels for detecting persistent or recurrent differentiated thyroid cancer in high- and low-risk patients

BACKGROUND

Serum thyroglobulin determination has been reported to be a sensitive indicator of persistent or recurrent differentiated thyroid cancer of follicular cell origin (DTC) after total thyroidectomy. The purpose of this investigation was to determine the accuracy of serum thyroglobulin levels in predicting persistent or recurrent DTC in euthyroid and hypothyroid patients.

METHODS

One hundred ninety consecutive patients with DTC of follicular cell origin who had 4 or more thyroglobulin levels measured after total thyroidectomy were retrospectively evaluated. One hundred fifteen patients had serum thyroglobulin levels measured when hypothyroid for radioiodine scanning or ablation. Serum thyroglobulin levels were determined by commercial assays. One hundred twenty-two patients less than 45 years old were considered at low risk, whereas 68 patients more than or equal to 45 years old were considered at high risk on the basis of TNM classification. The mean follow-up period was 62 months.

RESULTS

After thyroidectomy with or without central or modified radical neck dissection 120 patients had normal thyroglobulin levels (< or = 3 ng/mL) while receiving thyroid hormone. One hundred thirteen of the 120 patients (94%) with normal serum thyroglobulin levels had no evidence of recurrent tumor, whereas 6% (7 patients) had persistent or recurrent disease. Among 76 patients with persistent (28 patients) or recurrent (48 patients) disease, 70 had a serum thyroglobulin level > 3 ng/mL while receiving thyroid hormone. Overall, 14 of 115 patients, including 2 of 61 (3%) in the high-risk group and 12 of 54 (22%) in the low-risk group, only had elevated serum thyroglobulin levels when hypothyroid with high serum thyroid-stimulating hormone (TSH) levels documenting persistent or recurrent disease. In 1 patient the serum thyroglobulin level (240 ng/mL) was falsely elevated probably as a result of interfering antibodies because no tumor was identified surgically or pathologically, and the thyroglobulin concentration was < 3 ng/mL when analyzed in 3 other laboratories.

CONCLUSION

Serum thyroglobulin testing is sensitive (91%) and specific (99%) for identifying patients with persistent or recurrent differentiated thyroid cancer. Serum thyroglobulin levels are most precise when patients are hypothyroid (high TSH) and may be unreliable in patients with antithyroglobulin antibodies. We recommend TSH-stimulated thyroglobulin testing for all patients after total thyroidectomy for differentiated thyroid cancer of follicular cell origin regardless of patient age or risk group.

The predictive value of serum thyroglobulin in the follow-up of differentiated thyroid cancer

A strict and careful strategy has to be adopted to cure thyroid cancer. Diagnostic iodine-131 whole-body scan (WBS) and serum thyroglobulin (Tg) are important tools to detect thyroid remnants after thyroidectomy and radioiodine therapy. The aim of this retrospective study was to compare the relative sensitivity of WBS and Tg in the detection of thyroid remnants or metastases and to evaluate the predictive value of Tg in the clinical and scintigraphic course of the disease. Ninety-three patients were followed up after total thyroidectomy and the administration 4-6 weeks later of an ablative dose of 100 or 150 mCi 131I. Eighty-five percent of the patients were free of regional or distant metastases. The follow-up scheme included clinical examination of the patient followed by WBS, Tg, thyroid-stimulating hormone and free thyroxine measurements performed 4 weeks after thyroxine withdrawal and the observance of a low-iodine diet for at least 1 week. WBS (+) patients received a 100- or 150-mCi therapeutic dose of 131I. All patients were further followed up in the same way every 6 months until both WBS and Tg became negative, and thereafter at 1-, 2- and 4-year intervals. Six months after the postoperative radioiodine treatment (first visit), the sensitivity of WBS and Tg was 87% and 26% respectively. Among patients who were WBS(+) at the first visit, 95% of those who were Tg(-) and 47% of those who were Tg(+) had become disease-free at a median of 4 years after surgery (chi2=13.6; P<0.05). Patients whose tests were both positive required more radioiodine to be cured (335+/-90 vs 250+/-95 mCi; P<0.05). Our data indicate that in early diagnosed thyroid cancer, serum Tg measured 6 months after the postoperative 131I ablative dose is less sensitive than WBS for the demonstration of persistence of residual thyroid tissue but provides predictive information on the disease course. WBS(+) and Tg(-) patients are cured earlier and with less radioiodine than those who remain Tg(+).

Surgical considerations and approach to thyroid cancer

Patients with thyroid cancer can be safely treated by an experienced endocrine surgeon. More extensive initial surgery such as total or near-total thyroidectomy seems to decrease tumor recurrence and prolong life. When such operations can be done with minimal complications, we believe it is the treatment of choice because even low-risk patients have a 4% or 5% risk of eventually dying of thyroid cancer. If this risk of death from thyroid cancer can be decreased to 1% or 2% and the rate of serious complications is 1% or 2%, the authors believe total thyroidectomy is indicated. Most patients can be discharged within 1 day of total thyroidectomy.

Advances in the management of patients with thyroid disease

Discoveries related to thyroid immunology, especially concerning the thyroid-stimulating hormone (TSH) receptor, may facilitate new immunologic approaches to the therapy of Graves' disease and the thyroiditis syndromes. Advances in genetics are being applied to the thyroid hormone resistance syndromes and papillary and medullary carcinomas. The development of ever more sensitive TSH assays has led to the detection of subclinical thyroid disease, which has special implications for the sick and elderly patients. Sensitive TSH assays also allow more precise titration of levothyroxine (T4) dosages, especially for patients with a past history of thyroid cancer. Evidence continues to accumulate suggesting that postmenopausal women on T4 doses that suppress the TSH level below 0.1 ulU/mL have lower bone mineral density than matched patients with healthy TSH levels. Also, pregnant hypothyroid women need higher T4 doses to normalize the TSH levels. In the evaluation of thyroid nodules, fine-needle aspiration biopsy is the single most definitive modality in selecting the patients for surgery. Scintigraphy provides a complimentary role, especially in defining autonomously functioning thyroid adenomas (AFTA), because these should not be treated with T4 suppression. Ultrasound-guided needle biopsy is occasionally helpful with nodules that are difficult to palpate. Concern for possible tracheal compression after treatment of toxic multinodular goiter with large doses of radioactive iodine (I-131) in the range of 50 to 150 mCi (1.85 to 5.5 GBq) does not seem warranted. Work, primarily out of Italy, suggests AFTA can be ablated with repeat ethanol injections. Residual tissues after thyroidectomy for differentiated carcinoma can be "stunned" by tracer doses of 131I greater than 3.0 mCi (111 MBq), which diminishes the uptake and effectiveness of a subsequent therapy dose. Positron emission tomograph, imaging with thallium-201, and Technetium 99m Sestamibi can identify a small number of patients shown to have metastases from differentiated thyroid carcinoma by increasing thyroglobulin levels in the absence of 131I uptake. Several groups have recently advocated treating such patients empirically with 131I.