Effect of postoperative 131I treatment on thyroglobulin measurements in the follow-up of patients with thyroid cancer

FDG PET Predicts the Effects of 131I and Prognosis for Patients with Bone Metastases from Differentiated Thyroid Carcinoma

Background

¹⁸F-FDG PET and ¹³¹I scans are important in the detection of metastases from differentiated thyroid carcinoma (DTC). The relationship of FDG and radioiodine (RAI) metabolism in bone metastases (BMs) from DTC and its prognostic value on RAI treatment is not clear.

Methods

The retrospective study included DTC patients with BMs from two medical centers, who underwent ¹⁸F-FDG PET/CT scans and RAI therapy. Therapeutic response was evaluated by serum thyroglobulin (Tg) levels and anatomical imaging changes.

Results

The analyses were performed on 30 patients with 72 BMs. Forty-two (42/72, 58%) lesions displayed simultaneous ¹³¹I and ¹⁸F-FDG uptake. BMs with positive ¹⁸F-FDG uptake had a less favorable response to RAI therapy in comparison to those with negative ¹⁸F-FDG uptake (p = 0.018), even in ¹³¹I-avid lesions (p = 0.033). Sixteen (53%) patients had disease progression with a median PFI of 26 months (range: 3 to 89 months). Compared to those with ¹³¹I-avid but non-FDG-avid BMs, patients presenting with ¹⁸F-FDG-avid BMs had shorter PFI, whether with ¹³¹I uptake (p = 0.002) or without (p = 0.002).

Conclusion

More than half of BMs (58%) from DTC show simultaneous ¹⁸F-FDG and ¹³¹I uptakes which are contrary to the flip-flop phenomenon (¹³¹I negative and ¹⁸F-FDG positive). Regardless of ¹³¹I uptake, ¹⁸F-FDG uptake of BMs portends a less favorable therapeutic response and poorer prognosis for patients with DTC.

Changes in Serum Thyroglobulin Levels After Lobectomy in Patients with Low-Risk Papillary Thyroid Cancer

BACKGROUND

Low-risk patients with differentiated thyroid cancer can be treated with thyroid lobectomy. Serial measurements of serum thyroglobulin (Tg) are recommended for surveillance, but the cutoff values indicating recurrence are not known. This study documented the natural course of serum Tg levels during follow-up after lobectomy for low-risk papillary thyroid carcinoma (PTC) and evaluated whether changes in serum Tg levels predict disease recurrence.

METHODS

This historical cohort study included 208 patients with low-risk PTC who underwent lobectomy but did not require hormone replacement. Postoperative serum Tg levels and Tg/thyrotropin (TSH) ratios and neck ultrasound were evaluated during a follow-up period with a median of 6.9 years.

RESULTS

The serum Tg levels increased gradually, and the proportion of patients with levels >10 ng/dL increased annually by 13.9%, 18.8%, 22.1%, 21.9%, 28.4%, and 28.9% during the six-year follow-up period (β = 0.574, p = 0.027). The relative serum Tg levels increased by 10% annually (β = 0.105, p < 0.001), and the levels of Tg and Tg/TSH ratios in 19 patients with recurrent disease did not differ significantly (β = 0.150, p = 0.090). Patients without recurrent disease were more likely to have serum Tg levels increased by >20% (p = 0.022). There were no significant differences in the proportions of patients with serum Tg levels increased by ≥50% or ≥100% in terms of the disease recurrence.

CONCLUSIONS

Serum Tg levels and the Tg/TSH ratio increased gradually after lobectomy in patients with and without recurrences, without any significant differences. Periodic measurements of serum Tg levels seem to have limited value in predicting recurrent PTCs after lobectomy.

Thyroid Lobectomy Is Associated with Excellent Clinical Outcomes in Properly Selected Differentiated Thyroid Cancer Patients with Primary Tumors Greater Than 1 cm

Background and Objective. An individualized risk-based approach to the treatment of thyroid cancer is being extensively discussed in the recent literature. However, controversies about the ideal surgical approach remain an important issue with regard to the impact on prognosis and follow-up strategies. This study was designed to describe clinical outcomes in a cohort of low and intermediate risk thyroid cancer patients treated with thyroid lobectomy. Methods. Retrospective review of 70 patients who underwent lobectomy. Results. After a median follow-up of 11 years, 5 patients (5/70, 7.1%) recurred and 5 had a completion for benign lesions, while 60 patients (86%) continued to be observed without evidence for disease recurrence. Suspicious ultrasound findings were significantly more common in patients that had structural disease recurrence (100% versus 4.3%, P < 0.001). Furthermore, a rising suppressed Tg value over time was also associated with structural disease recurrence (80% versus 21.5%, P = 0.01). After additional therapy, 99% of the patients had no evidence of disease. Conclusions. Properly selected thyroid cancer patients can be treated with lobectomy with excellent clinical outcomes.

Initial therapy with either thyroid lobectomy or total thyroidectomy without radioactive iodine remnant ablation is associated with very low rates of structural disease recurrence in properly selected patients with differentiated thyroid cancer

OBJECTIVE

To describe the risk of structural disease recurrence in a cohort of patients with differentiated thyroid cancer selected for treatment with either thyroid lobectomy or total thyroidectomy without radioactive iodine remnant ablation (RRA).

DESIGN

Retrospective review.

PATIENTS

A total of 289 patients were selected for either thyroid lobectomy (n = 72) or total thyroidectomy (n = 217) without RRA and followed with modern disease detection tools in a tertiary referral centre. Most patients had papillary thyroid cancer (89%) without clinically evident lymph node metastases (91%). However, 55% (156/289) of patients had primary tumours that were >1 cm and 10% (28/289) had minor extrathyroidal extension.

MEASUREMENTS

The primary endpoint was detection of recurrent/persistent structural disease.

RESULTS

After a 5-year median follow-up, structural disease recurrence was detected in 2·3% (5/217) of patients treated with total thyroidectomy without RRA, and in 4·2% (3/72) of patients treated with thyroid lobectomy. Size of the primary tumour, the presence of cervical lymph node metastases and American Thyroid Association risk category were all statistically significant predictors of recurrence. Changes in serum thyroglobulin were not helpful in identifying the presence of persistent/recurrent structural disease. Importantly, 88% (7/8) of the patients that had recurrent disease were rendered clinically disease free with additional therapies.

CONCLUSIONS

Initial risk stratification is able to identify a cohort of patients with differentiated thyroid cancer with a very low risk of structural disease recurrence following treatment with either thyroid lobectomy or total thyroidectomy without RRA. Our data strongly support a selective approach to the initial management of thyroid cancer.

The local efficacy of I-131 for F-18 FDG PET positive lesions in patients with recurrent or metastatic thyroid carcinomas

PURPOSE

The aim of this study was to evaluate the local efficacy of I-131 for F-18 fluorodeoxyglucose positron emission tomography (FDG PET)-positive lesions.

METHODS

Whole-body FDG PET/CT was performed on 37 patients (55 cases: 16 men, 21 women; age range: 24-82 years; mean age ± standard deviation: 60.5 ± 16.0 years) with differentiated thyroid cancer after total thyroidectomy. The metastatic or recurrent lesions were divided into 5 categories: primary tumor bed, lymph node, lung, bone, and other. The well-defined lesions were measured on CT, and the sizes were compared before and after radioactive iodine therapy.

RESULTS

The analysis was performed on 37 patients with 44 lesions (lymph node:24, lung:16, bone:4). Sixteen lesions (70%) were increased and 7 (30%) showed no change or reduction when there was positive accumulation on FDG PET/CT and negative accumulation on I-131 (F(+)I(-)) group. In the positive accumulation for both FDG PET/CT and I-131 (F(+)I(+)) group, 5 lesions (63%) were increased and 3 (37%) showed no change or reduction. There was no significant difference for the tendency to increase in size between the F(+)I(-) and the F(+)I(+) groups.

CONCLUSIONS

Lesions which show positive accumulations on FDG PET/CT have a greater tendency to increase in size. FDG-avid lesions are resistant to radioactive iodine therapy with or without I-131 uptake.

Aerodigestive Tract Invasion by Well-Differentiated Thyroid Carcinoma: Diagnosis, Management, Prognosis, and Biology

OBJECTIVES/HYPOTHESIS

1) To describe the clinical entity invasive well-differentiated thyroid carcinoma (IWDTC), 2) to determine prognostic factors for survival in patients with IWDTC, 3) to describe and compare types of surgical resection to determine treatment efficacy, 4) to offer a staging system and surgical algorithm for management of patients with IWDTC, 5) to examine alterations in expression of E-cadherin and beta-catenin adhesion molecules in three groups of thyroid tissue and propose a cellular mechanism for invasion of the aerodigestive tract.

STUDY DESIGN

Basic science: quantification of expression of E-cadherin and beta-catenin in three groups of thyroid tissue. Clinical: retrospective review of patients with IWDTC surgically treated and followed over a 45-year time period.

METHODS

Basic science: immunohistochemical staining was used with antibodies against E-cadherin and beta-catenin in three groups of tissue: group 1, normal control thyroid tissue (n = 10); group 2, conventional papillary thyroid carcinoma (n = 20); group 3, IWDTC (n = 12). Intensity scores were given on the basis of protocol. One-way analysis of variance (ANOVA) was used to evaluate differences between groups. Post hoc ANOVA testing was completed. P < .05 was significant. Clinical: patients were divided into three surgical groups within the laryngotracheal subset: group 1, complete resection of gross disease (n = 34); group 2, shave excision (n = 75); group 3, incomplete excision (n = 15). Cox regression analysis was used to determine significance of prognostic factors. Kaplan-Meier plots were used to evaluate survival. P < .05 was significant.

RESULTS

Basic science: a significant difference between the three thyroid tissue groups for E-cadherin expression was demonstrated on one-way ANOVA testing. When controls were compared with either experimental group in post hoc ANOVA testing, differences between all groups were demonstrated (P < .001). For beta-catenin, the intensities of the three groups were not different by one-way ANOVA testing. Similar nonsignificant results were found on post hoc ANOVA testing. Clinical: there was a statistically significant difference in survival for patients with and without involvement of any portion of the endolarynx or trachea (P < .01). There was a significant difference among all three surgical groups when compared (P < .001). When complete and shave groups were compared with gross residual group there was a significant decrease in survival in incomplete resection group (P < .01). Cox regression analysis demonstrated invasion of larynx and trachea were significant prognostic factors for poor outcome. The type of initial resection was significant on multivariate analysis. Removal of all gross disease is a major factor for survival.

CONCLUSIONS

Basic science: there is a decrease in membrane expression of E-cadherin in IWDTC, and loss of this tumor suppressor adhesion molecule may contribute to the invasive nature of well-differentiated thyroid carcinomas. Clinical: laryngotracheal invasion is a significant independent prognostic factor for survival. Patients undergoing shave excision had similar survival when compared with those undergoing radical tumor resection if gross tumor did not remain. Gross intraluminal tumor should be resected completely. Shave excision is adequate for minimal invasion not involving the intraluminal surfaces of the aerodigestive tract.

Diagnostic value of serum thyroglobulin measurements in the follow-up of differentiated thyroid carcinoma, a structured meta-analysis

OBJECTIVE

To investigate to what extent thyroid remnant ablation and withdrawal from thyroxine are required to achieve sufficient accuracy of serum thyroglobulin (Tg) measurements as an indicator of tumour recurrence in the follow-up of patients with differentiated thyroid carcinoma.

DESIGN AND METHODS

We conducted a meta-analysis of the literature from 1975 to 2003 on serum Tg measurements in the follow-up of differentiated thyroid carcinoma. In a computer-based search, we initially found 915 articles that were finally narrowed down to 120. These 120 papers were subjected to strict in/and exclusion criteria, leaving 46 articles (totalling 9094 patients). Data from these articles were extracted in a structured fashion and were grouped according to initial therapy, TSH status, Tg assay method and definition of a 'gold standard'. Original 2 x 2 tables were pooled by summary receiver operating characteristic curve analysis (sROCa), best estimates of sensitivity and specificity being obtained by the combination of sROCa and Mantel-Haenszel odds ratios.

RESULTS

Despite considerable differences between series in laboratory and clinical methodology, we consistently found higher specificity for Tg measurements after thyroid remnant ablation than after surgery alone. Highest pooled sensitivity 0.961 +/- 0.013 (SE) was found for immunometric assay (IMA) after thyroid remnant ablation and thyroid hormone withdrawal, at a specificity of 0.947 +/- 0.007. Pooled sensitivity decreased significantly if ablated patients were tested while on thyroid hormone (0.778 +/- 0.023, at a specificity of 0.977 +/- 0.005). Significantly decreased pooled specificity was found in patients who did not undergo remnant ablation (sensitivity 0.972 +/- 0.023, at a specificity of 0.759 +/- 0.028). If recombinant human TSH (rhTSH) stimulation was used as a substitute for thyroxine withdrawal, sensitivity remained high (0.925 +/- 0.018) while specificity decreased to 0.880 +/- 0.013. In all analyses, specificity of Tg would decrease when unspecified activity in the thyroid region at scintigraphy was considered benign, whereas sensitivity decreased when such activity was considered malignant.

CONCLUSION

This study confirms that the best accuracy of Tg-guided follow-up in patients treated for differentiated thyroid carcinoma is obtained if treatment includes remnant ablation, and Tg testing is performed while off thyroxine.

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.

Recombinant human thyrotropin stimulation of thyroglobulin in the follow-up of patients with stage I or II differentiated thyroid carcinoma

OBJECTIVE

To present an approach for follow-up of low-risk patients who have undergone treatment for differentiated thyroid carcinoma.

METHODS

We review our experience with monitoring of 167 patients who had undergone near-total thyroidectomy for stage I or II thyroid carcinoma and were receiving levothyroxine and discuss the advantages and disadvantages of various tests for detection of recurrent disease in this setting.

RESULTS

Almost 200,000 patients who have been treated for thyroid cancer live in the United States and require monitoring for possible recurrence of their disease. Most of these patients had stage I or II well-differentiated cancer. A cost-efficient method of follow-up for these low-risk patients is needed that relies on measurement of serum thyroglobulin (Tg) rather than expensive isotope imaging procedures. The availability of recombinant human thyrotropin (thyroid-stimulating hormone) (rhTSH) allows the evaluation of Tg dynamics and provides another method, along with ultrasonography, to monitor these patients. Among our 167 patients, 10 had Tg measurements of 2.5 to 5.0 ng/mL and were thought to be at risk for recurrent cancer. Ultrasonography of the neck revealed no suspicious lymph nodes. Tg response to rhTSH stimulation disclosed that two of these patients had an exaggerated increase in Tg level, compatible with persistent or recurrent cancer.

CONCLUSION

Although rhTSH stimulation testing has not yet become established in clinical practice, the finding of an exaggerated Tg response to rhTSH in patients with previously treated thyroid cancer seems to be an early indication of recurrent disease.

Comparison of two thyroglobulin immunoradiometric assays on the basis of comprehensive imaging in differentiated thyroid carcinoma

The aim was to compare two thyroglobulin-immunoradiometric assays (Tg-IRMA) in the follow-up of patients with differentiated thyroid carcinoma (DTC) in order to set up interassay correlation, correlation to clinical background, and to determine whether a lower functional sensitivity (kit A: 0.5 ng/mL, kit B: 0.3 ng/mL) would allow an earlier detection of recurrences. Three hundred eight samples from 181 patients with DTC were investigated. The clinical interpretation of the Tg-IRMA results was based on comprehensive imaging and the clinical history before and during the study period. Groups were formed against this background and against the thyrotropin (TSH) levels of the samples (LT4- on and LT4-off). During a follow-up period that lasted until September 1998, the clinical situation was reevaluated in order to determine any changes in the patients' clinical status. The two assays presented a good interassay correlation of 0.838. Both assays had a high and comparably good sensitivity in the detection of recurrence of malignancy or distant metastases. Patients in remission had, in most cases, nonmeasurable or Tg values below 1 ng/mL. Kit B presented slightly measurable Tg results in a larger number of patients in remission; however, during the follow-up most of these slightly measurable Tg results were not reproducible, thus being most likely artifacts. Consequently, the functional sensitivity of 0.3 ng/mL of kit B showed no advantages in terms of an earlier tumor detection and seems to be unacceptably low. Negative consequences may be an increase in the number of investigations during the follow-up, which may be disconcerting for both the clinicians and the patients.

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.

Follicular neoplasms: the role for observation, fine needle aspiration biopsy, thyroid suppression, and surgery

The diagnosis and management of follicular carcinoma of the thyroid gland remains a controversial topic. Fine needle aspiration, although very sensitive with other types of thyroid cancer, has limited accuracy with follicular lesions. The role of suppression combined with observation has yet to gain widespread acceptance. The extent of surgical excision of follicular carcinoma also raises several competing views. The goal of this review is to address these issues and present an algorithm for the management of follicular neoplasms of the thyroid.

131I treatment of 131I negative whole body scan, and positive thyroglobulin in differentiated thyroid carcinoma: what is being treated?

Several aspects of the management of differentiated thyroid cancer cause considerable controversy. Among these is the role of 131I therapy in patients after thyroidectomy. There is no controlled study to demonstrate whether this treatment reduces the recurrence rate or improves mortality. Because of the overall excellent prognosis, it is unlikely that a controlled study will ever be conducted. Most frequently, patients have a diagnostic scan with 131I to determine whether radioiodine would be an appropriate therapy and to judge much to be prescribed, based on the extent of abnormalities seen on the scintiscan. Serum thyroglobulin (Tg) has been found to be a valuable tumor marker, with very good sensitivity and specificity. In most patients, the result of whole-body 131I scintiscan and Tg measurement give concordant results. However, in some patients, Tg is measurable, but the diagnostic scan with 131 is normal. There has been data published about treatment of these patients with therapeutic doses of 131I. The author questions whether this treatment is appropriate, prompted by seeing and hearing of patients who were treated with therapeutic doses of 131I, but had no abnormal uptake of the therapeutic doses and who had no improvement in serum Tg level. These patients have no clinical evidence of disease, and the only abnormality is measurable Tg. Since large doses of radioiodine are not without problems, a controlled clinical trial should be developed to evaluate efficacy in this situation.

Is serum thyroglobulin a useful marker for thyroid cancer in patients who have not had ablation of residual thyroid tissue?

Serum thyroglobulin has been measured sequentially in 47 patients with differentiated thyroid cancer who had been treated by surgery and I-thyroxine, but no radioiodine (131I). In 39 of the patients, the operation was subtotal or total thyroidectomy, and in 8 patients it was lobectomy, or lobectomy plus isthmusectomy. In the first group of patients, serum thyroglobulin (Tg) was consistently undetectable in 62% and less than 5 ng/mL in 85%. In the latter group only 1 patient had undetectable Tg values and 2 (25%) had values less than 5 ng/mL. Even in those with higher Tg values, the levels remained constant within a narrow range, provided thyrotropin (TSH) was not high. Serum Tg can be used in conjunction with clinical evaluation in follow-up of patients with differentiated thyroid cancer who have had an operation consisting of more than lobectomy and isthmusectomy and have not been treated with 131I. Its use in patients with lesser operations has to be interpreted in relation to the amount of thyroid left and to the consistency of the results with time.

Thyroid Ultrasonography—A Review

OBJECTIVE

To review the major applications of ultrasonography in studies of the thyroid gland by clinical endocrinologists.

METHODS

The techniques for performance of thyroid ultrasonography and ultrasound-guided fine-needle aspiration biopsy are outlined, and the settings for their use are discussed. Characteristic findings and limitations are described.

RESULTS

In two situations--the assessment of thyroid nodules and the postoperative follow-up of thyroid cancer--ultrasonography and ultrasound-guided fine-needle aspiration biopsy have proved to be clinically useful when used in combination. On ultrasonography, a hyperechoic nodule with a sharp "halo" is associated with a low risk of malignancy and a hypoechoic nodule with microcalcifications is associated with a high risk of a malignant lesion, but performance of a biopsy is recommended. Ultrasonography coupled with ultrasound-guided fine-needle aspiration biopsy can detect >90% of recurrent cases of thyroid carcinoma. In general, normal lymph nodes appear flattened on ultrasonography, whereas malignant nodes appear more rounded or bulging.

CONCLUSION

Thyroid ultrasonography and fine-needle aspiration biopsy are complementary diagnostic procedures in the evaluation of thyroid nodules and for detection of recurrent or metastatic thyroid carcinoma.

Thyroglobulin: A Clinical Review

The introduction of the new assays for thyroglobulin (Tg) with a sensitivity of 1 to 3 mg/L has made it unnecessary to terminate thyroxine suppression therapy to determine Tg level. Thyroid-stimulating hormone should always be assessed in conjunction with the Tg to ensure that it is not high; as long as it is suppressed to normal, subnormal suppression is unnecessary. A total thyroidectomy is not a prerequisite for using Tg as a tumor marker; the Tg is equally reliable in those patients who have undergone a near-total or a subtotal thyroidectomy. Even patients who have undergone only a lobectomy may benefit from Tg monitoring if the level is low; however, an initial high Tg level (without a previous low Tg value) should not be interpreted as suggestive of cancer. Postoperative 131 I ablation is not necessary for an accurate Tg measurement. The finding of anti-Tg antibodies in patients with thyroid cancer remains a major problem, but other technical problems related to the absence of an international Tg standard have now been eliminated. Monitoring the Tg level reliably detects early recurrent disease in patients who have undergone a surgical procedure for thyroid carcinoma and are receiving thyroxine suppression therapy. Only those patients with Tg levels that exceed 3 to 5 mg/L or with clinical evidence of recurrence need to discontinue thyroxine treatment and have a 131 I scan. This approach can substantially decrease the expense, inconvenience, and morbidity of performing routine scans on these patients.