A new immunoradiometric assay (IRMA) system for thyroglobulin measurement in the follow-up of thyroid cancer patients

Evaluation of a new automated assay for high-sensitivity thyroglobulin measurement and comparison with two established high-sensitivity thyroglobulin assays

Objective

Thyroglobulin (Tg) is an important tumor marker for therapy control and follow-up of differentiated thyroid carcinoma (DTC). Over the past decade, assays for highly sensitive Tg measurement have become increasingly established. We evaluated a newly developed high-sensitive Tg assay running on an automated platform (LIAISON® Tg II Gen assay, DiaSorin), with a limit of quantification of 0.10 ng/ml.

Design and Methods

Tg values of 166 sera from subjects without thyroid diseases and of more than 500 sera of well-defined DTC patients were determined with the new LIAISON® Tg II Gen assay and compared with two established assays (Elecsys® Tg II/Roche, and Medizym® Tg REM/Medipan).

Results

Tg reference values from healthy subjects were up to 37.93 ng/ml (women) resp. 24.59 ng/ml (men) with the LIAISON® Tg II Gen assay. Tg values showed good correlations in healthy subjects and patients with active tumorous disease. In contrast, Tg values in the very low range from cured thyroidectomized patients were poorly comparable between the three assays, while clinical differences between the cohorts were correctly reflected by all assays.

Conclusions

With the new LIAISON® Tg II Gen assay, another automated assay standardized against the first International Reference Preparation CRM-457 for highly sensitive measurement of Tg values is available.

Value of thyroglobulin post hemithyroidectomy for cancer: a literature review

BACKGROUND

An increasing number of patients with low and moderate risk differentiated thyroid cancer (DTC) are now managed with lobectomy alone. The value of serum thyroglobulin (Tg) in the follow up of these patients remains poorly defined.

METHODS

A review of the MEDLINE and EMBASE databases was performed to assess the utility of Tg in the follow up of patients undergoing thyroid lobectomy for DTC.

RESULTS

A total of five retrospective reviews were identified including 1136 patients undergoing hemithyroidectomy with or without prophylactic central neck dissection. The overall locoregional recurrence rate was 3.7%. Changes in serum Tg following hemithyroidectomy for cancer were found to be clinically useful in one study only. The proposed cut-off value of 30 ng/mL following hemithyroidectomy as a predictor of recurrent disease was not validated by any study.

CONCLUSION

Serum Tg values are not useful in the follow up of DTC patients managed with lobectomy alone. Good quality neck ultrasound appears to be an effective modality in the detection of locoregional recurrence in these patients while research efforts continue to identify and validate novel biomarkers.

Diagnostic value and therapeutic impact of 18F-FDG-PET/CT in differentiated thyroid cancer

The clinical significance of 18F-FDG-PET/CT in the follow-up of patients with differentiated thyroid carcinoma was evaluated and the results were compared with those of 18F-FDGPET, 131I-whole-body scintigraphy including SPECT/CT (WBS) and ultrasound. In addition, it was the aim to investigate the impact of 18F-FDG-PET/CT on the therapeutic management. Patients, methods: 327 patients (209 women, 118 men; mean age 53 ± 18 years) with differentiated thyroid cancer (242 papillary, 75 follicular, 6 mixed, 1 Hürthle cell and 3 poorly differentiated tumours) were analyzed retrospectively at four tertiary referral centres. 289 18F-FDG-PET/CT and 118 18F-FDG-PET studies were performed in these patients between 2007 and 2010. In addition, an overall clinical evaluation was performed, including cytology, histology, thyroglobulin level, ultrasound, WBS, and subsequent clinical course in order to compare the molecular imaging results. Finally, the change in therapeutic management due to findings of 18F-FDG-PET/CT was investigated. Results: The sensitivity of 18F-FDG-PET/CT was 92%, the specificity was 95%. Sensitivity and specificity of 18F-FDG-PET alone were 67% and 93%, respectively. WBS showed a sensitivity of 65% and a specificity of 94%. The corresponding values of ultrasound were 37% and 94%, respectively. The sensitivity of 18F-FDG-PET/CT in the group of patients with a negative WBS (n=194) amounted to 96%. When 18F-FDG-PET/CT and WBS were considered in combination, tumour tissue was missed in only 2 out of 133 patients; when 18F-FDG-PET and WBS were combined, tumour tissue was missed in 1 out of 24 patients. 18F-FDG-PET/CT resulted in management change in 43% (n=57/133) with a decision on surgical approach in 20% (n=27/133). Conclusions: 18F-FDG-PET/CT is superior to 18F-FDG-PET alone in patients with differentiated thyroid cancer and has a direct impact on the therapeutic management of patients with suspected local recurrence or metastases, particularly in those with negative WBS.

Reliability of thyroglobulin in serum compared with urinary iodine when assessing individual and population iodine nutrition status

The occurrence of thyroid disorders relies on I nutrition and monitoring of all populations is recommended. Measuring I in urine is standard but thyroglobulin in serum is an alternative. This led us to assess the reliability of studies using serum thyroglobulin compared with urinary I to assess the I nutrition level and calculate the number of participants needed in a study with repeated data sampling in the same individuals for 1 year. Diet, supplement use and life style factors were assessed by questionnaires. We measured thyroglobulin and thyroglobulin antibodies in serum and I in urine. Participants were thirty-three Caucasians and sixty-four Inuit living in Greenland aged 30–49 years. Serum thyroglobulin decreased with rising I excretion (Kendall’sτ−0·29,P=0·005) and did not differ with ethnicity. Variation in individuals was lower for serum-thyroglobulin than for urinary I (mean individual CV: 15·1v. 46·1 %;P<0·01). It required 245 urine samples to be 95 % certain of having a urinary I excretion within 10 % of the true mean of the population. For serum-thyroglobulin the same precision required 206 samples. In an individual ten times more samples were needed to depict I deficiency when using urinary I excretion compared with serum-thyroglobulin. In conclusion, more participants are need to portray I deficiency in a population when using urinary I compared with serum-thyroglobulin, and about ten times more samples are needed in an individual. Adding serum-thyroglobulin to urinary I may inform surveys of I nutrition by allowing subgroup analysis with similar reliability.

Does (131)I Radioactivity Interfere with Thyroglobulin Measurement in Patients Undergoing Radioactive Iodine Therapy with Recombinant Human TSH?

OBJECTIVES

Recombinant human thyroid-stimulating hormone (rhTSH) is widely used in radioactive iodine therapy (RIT) to avoid side effects caused by hypothyroidism during the therapy. Owing to RIT with rhTSH, serum thyroglobulin (Tg) is measured with high (131)I concentrations. It is of concern that the relatively high energy of (131)I could interfere with Tg measurement using the immunoradiometric assay (IRMA). We investigated the effect of (131)I administration on Tg measurement with IRMA after RIT.

METHODS

A total of 67 patients with thyroid cancer were analysed retrospectively. All patients had undergone rhTSH stimulation for RIT. The patients' sera were sampled 2 days after (131)I administration and divided into two portions: for Tg measurements on days 2 and 32 after (131)I administration. The count per minute (CPM) of whole serum (200 μl) was also measured at each time point. Student's paired t-test and Pearson's correlation analyses were performed for statistical analysis.

RESULTS

Serum Tg levels were significantly concordant between days 2 and 32, irrespective of the serum CPM. Subgroup analysis was performed by classification based on the (131)I dose. No difference was noted between the results of the two groups.

CONCLUSIONS

IRMA using (125)I did not show interference from (131)I in the serum of patients stimulated by rhTSH.

Thyroid hyperactivity with high thyroglobulin in serum despite sufficient iodine intake in chronic cold adaptation in an Arctic Inuit hunter population

OBJECTIVE

Adult man hosts brown adipose tissue with the capacity to consume energy and dissipate heat. This is essential for non-shivering thermogenesis and its activation depends on sympathetic activity and thyroid hormones. This led us to evaluate the impact of chronic cold exposure on thyroid activity and thyroid hormones in serum in Arctic residents.

DESIGN

Comparative, population-based study (n = 535) performed in Greenland.

METHODS

Hunters were compared with other men, and Inuit in remote settlements in East Greenland with no modern housing facilities were compared with the residents of the capital city in West Greenland and residents of a major town in East Greenland in a cross-sectional study. We used interview-based questionnaires, measured TSH, free thyroxine, free triiodothyronine (fT(3)), thyroglobulin (TG) antibody and TG (a measure of thyroid activity) in serum, and iodine and creatinine in spot urine samples.

RESULTS

Serum TG was the highest among hunters (P = 0.009) and settlement dwellers (P = 0.001), who were most markedly exposed to cold, even though they had the highest urinary iodine excretion (hunters, P < 0.001; settlement dwellers, P < 0.001). Hunters and settlement dwellers also had the lowest fT(3) (hunters, P < 0.001; settlement dwellers, P < 0.001) after adjusting for gender, age, smoking habits, alcohol intake and iodine excretion in multivariate linear regression models. TSH was not influenced by measures of cold exposure (hunter, P = 0.36; residence, P = 0.91).

CONCLUSIONS

Cold exposure influenced thyroid hormones and TG in serum in Arctic populations consistent with consumption of thyroid hormone and higher thyroid hormone turnover. Findings emphasise that changes in thyroid activity are essential in cold adaptation in Arctic residents.

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.

Predictive value of serum thyroglobulin after surgery for thyroid carcinoma

OBJECTIVE

To determine the relationship between stimulated serum thyroglobulin levels (taken 3 months after total thyroidectomy) and tumor stage and recurrence in patients with well-differentiated thyroid carcinoma.

STUDY DESIGN

Retrospective chart review in a tertiary care institution.

METHODS

Two hundred thirteen consecutive patients with well differentiated thyroid carcinoma treated between 1983 and 1998 were identified. Data were collected on clinicopathological variables, stimulated serum thyroglobulin levels obtained 3 months after total thyroidectomy prior to 131I therapy and recurrence.

RESULTS

A high postoperative thyroglobulin level was significantly associated with advanced-stage disease at presentation (P =.005, Kruskall-Wallis) but not with any of the other clinicopathological variables. Patients with a thyroglobulin level greater than 20 pmol/L had a significantly increased risk of disease recurrence on univariate analysis (n = 213 [P =.0001, log rank test]), and in the Cox proportional-hazards model, both advanced tumor stage (P =.001, relative hazard, 3.4 [95% confidence interval [CI]: 2.4-4.9]) and a thyroglobulin level greater than 20 pmol/L (P =.001, relative hazard, 5.1 [95% CI: 2.0-13.1]) were significant predictors of recurrence. No other variables significantly altered the hazards model.

CONCLUSIONS

Advanced tumor stage at diagnosis and a stimulated thyroglobulin level greater than 20 pmol/L taken 3 months after total thyroidectomy were independent predictors of disease recurrence. Patients with a thyroglobulin level greater than 20 pmol/L are at increased risk of recurrence and may be candidates for more intensive follow-up or additional treatment.

Low goitre prevalence among users of oral contraceptives in a population sample of 3712 women

OBJECTIVE

Goitre occurs primarily in women. As oestrogens may be an aetiologic factor, the use of oral contraceptives (OC) could be associated with an increased risk of goitre. This is supported by experimental data, but a recent population study suggested decreased thyroid volumes among users of OC.

DESIGN

Cross-sectional, observational study.

PARTICIPANTS

A random population sample of 3712 women from two Danish cities.

MEASUREMENTS

Ultrasound and clinical examination of the thyroid, measurement of serum TSH, T3, T4 and thyroglobulin, and personal interviews with registration of use of OC or post-menopausal oestrogen therapy. Data were analysed in linear models and logistic regression adjusting for age and iodine status.

RESULTS

Thyroid volume was lower among users than non-users of OC, 11.1 ml vs. 12.1 ml (P < 0.001). Use of OC was correspondingly associated with a reduced prevalence of thyroid enlargement on ultrasound (odds ratio 0.53, 95% confidence interval 0.37-0.74) and of palpable and visible goitre (OR 0.24, 95% CI 0.07-0.81). Serum TSH was 1.24 mU/l in non-users of OC and 1.35 mU/l in users (P = 0.002). The percentage of goitre cases prevented by OC compared to a hypothetical population without use of OC was 29%. Post-menopausal oestrogen therapy showed similar, but statistically non-significant, associations.

CONCLUSION

Use of oral contraceptives was associated with a lower thyroid volume and reduced risk of goitre, and clinically evident goitre was four times more frequent among non-users than among users of oral contraceptives.

Prognostic value of serial serum thyroglobulin determinations after total thyroidectomy for differentiated thyroid cancer

Serial weekly serum samples (for 3 weeks) were obtained from 42 patients with differentiated thyroid cancer (DTC, papillary no.=35, follicular no.=6, Hurthle cell no.=1) for serum thyroid hormone, TSH and TG before and after total thyroidectomy. Serum specimens were also obtained one month after radioiodine (131I) therapy followed by suppressive dose of L-thyroxine (L-T4, 2.5 microg/kg). The patients were subdivided into four groups: group I: the DTC was confined to a single solid nodule (no.=1 2); group II: thyroid malignancy invaded local cervical structures but there were no lymph node metastases (no.=8); group III: DTC with lymph node metastases (no.=6); and group IV: DTC with distant metastases (no.=16). In all group I patients serum TG remained undetectable in spite of elevated serum TSH levels at the 3rd week post-surgery (PS). Only one of group II patients had a detectable serum TG value of 5.2 ng/ml (3rd week PS). By contrast, 37.5% of group III patients had detectable serum TG levels, ranging from 3.4 to 16.8 ng/ml (3rd week PS). Lymph node metastases were detected in 5 of these patients by whole body scan (WBS) and removed surgically in 3. As expected, group IV patients had elevated serum TG values ranging 33.0-958.0 ng/ml and distant metastases were confirmed in all of them by WBS. From the calculations through univariate logistic regression comparing TG concentrations at the 3rd week PS from groups I and II vs groups III and IV, we obtained a cut-off value of 2.3 ng/ml with the following efficacy features: sensitivity=74.5%; specificity=95%; positive predictive value=92.3%; negative predictive value=65.5%; and accuracy=73.8%. After 131I and L-T4 suppressive therapy, only 5 out of 36 patients of groups I, II and III had detectable serum TG levels (3.1-7.0 ng/ml) whereas serum TG was detectable in all group IV patients (ranging 2.5-8.6 ng/ml). We concluded that serum TG concentrations above 2.3 ng/ml at the 3rd week PS could be suggestive of lymph node or distant metastases in patients with DTC. Patients with serum TG above this limit could be considered at risk for metastatic disease and higher doses of diagnostic iodine-131 (131I) may be indicated for actinic ablation.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Thyroglobulin antibodies in differentiated thyroid cancer

A retrospective review of patients with differentiated thyroid cancer (DTC) who were seen between 1984 and 1996 at the Royal Marsden Hospital identified 40 patients with serum thyroglobulin antibodies (TgAb). These antibodies can interfere with the immunoradiometric assay for serum thyroglobulin (Tg) used at this hospital, with resulting underestimation of the Tg level. A review of the case notes was carried out to ascertain the clinical significance of TgAb. The median follow-up from diagnosis of DTC was 26 months (range 3-401). The median age at diagnosis of DTC was 50 years (range 13-83). Patients were grouped according to the TgAb titre (high titre: TgAb >1/100, n = 28; low titre TgAb <1/100, n = 12). Thirteen patients relapsed, 11 in the high titre group and two in the low titre group. Sites of recurrence were: neck (n = 9), lung (n = 5), bone (n = 4) and brain (n = 2). No patient in the high titre group showed an elevated Tg with recurrence. One patient in the low titre group showed a Tg response to recurrence. Overall, the Tg assay failed to detect 92% of recurrences. Eight patients in the high titre group developed TgAb, apparently in response to tumour progression. In a third patient in the low titre group, the TgAb also acted as a 'tumour marker'. Thus, overall TgAb acted as a tumour marker in nine of the 40 (22.5%) patients in whom it was detected, and in nine of the 470 (1.9%) patients on follow-up during this time period. The overall survival of the whole group was 69% at 10 years. For patients with papillary carcinoma (n = 34) overall survival was 78% at 10 years. Laboratories should report routinely the presence of TgAb, with a caution indicating the direction of possible error (which depends on the assay used). Clinicians should appreciate that Tg measurements are unreliable in the presence of TgAb and that the development of TgAb can indicate active tumour.

Appearance of antithyroglobulin antibodies as the sole sign of metastatic lymph nodes in a patient operated on for papillary thyroid cancer: a case report

We report a case in which the appearance of a progressively rising titer of thyroglobulin (Tg) antibodies was the most sensitive marker of papillary thyroid cancer relapse at loco-regional lymph nodes. The patient, a 60-year-old man, had been treated with total thyroidectomy plus lymphadenectomy and radioiodine ablation for a 1-cm papillary thyroid cancer. Twelve years after surgery, while undergoing levothyroxine (LT4) therapy, Tg antibodies were first detected and progressively rose from 99 to 1,697 U/mL in 18 months, while serum Tg remained undetectable. Both neck ultrasonography and 131I whole-body scan (WBS) were unremarkable. Enlarged lymph nodes became palpable at the left laterocervical region only 2 years after the first appearance of Tg antibodies and were surgically removed after cancer relapse was confirmed by fine-needle aspiration cytology. This case emphasizes the possibility that in thyroid cancer patients who have undergone total thyroidectomy, the appearance of Tg antibodies may indicate metastatic lymph nodes even when serum Tg is undetectable and WBS negative.

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.

Recurrent differentiated thyroid cancer without elevation of serum thyroglobulin

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

Degree of thyrotropin suppression in differentiated thyroid cancer without recurrence or metastases

Forty-eight patients with differentiated thyroid cancer (DTC), who had no evidence of tumor recurrence or metastases on studies such as radioiodine scanning, neck ultrasonography, and with thyrotropin (TSH) and thyroglobulin (Tg) levels less than 1 mU/L and 5 ng/mL, respectively, were included in the study. The mean age was 43 +/- 12 years (range 15-65) and all were receiving levothyroxine (LT4) treatment with a mean dose of 184 +/- 46 microg daily. Patients were divided into two groups; group A included patients that had baseline TSH levels of 0.4 mU/L or more, and group B patients had baseline TSH levels of less than 0.4 mU/L. LT4 doses for all patients were increased, and serum TSH and Tg measurements were reevaluated after 2 months of dose increments. The mean TSH of group A (patients with baseline TSH levels > or = 0.4 mU/L) decreased from 0.67 +/- 0.28 mU/L to 0.16 +/- 0.08 mU/L (p < 0.001), but mean serum Tg level showed no change after dose increments (2.92 +/- 1.36 ng/mL vs. 3.59 +/- 0.93 ng/mL at the second month; p > 0.05). Similar results were also observed in group B (patients with baseline TSH levels < 0.4 mU/L). Mean TSH level decreased from 0.26 +/- 0.07 mU/L to 0.1 +/- 0.05 mU/L (p = 0.006), but no decrease occurred in mean Tg level (3.0 +/- 1.16 ng/mL vs. 3.3 +/- 1.03 ng/mL; p > 0.05). The patients' data were reevaluated according to second-month TSH levels. Patients with a TSH level between 0.11 to 0.4 mU/L were set as "final TSH > 0.1 group," and patients with a TSH level equal or less than 0.1 mU/L were set as "final TSH < or = 0.1 group," and baseline and second-month Tg levels were assessed. The mean second month Tg levels did not differ in these two patient groups (3.7 +/- 0.74 ng/mL for final TSH > 0.1 group vs. 3.3 +/- 1.2 ng/mL for final TSH < or = 0.1 group; p > 0.05). No difference could be found between initial and second-month Tg levels in both groups (2.8 +/- 1.4 ng/mL vs. 3.7 +/- 0.74 ng/mL in final TSH > 0.1 group and 3.11 +/- 1.1 ng/mL vs. 3.3 +/- 1.2 in final TSH < or = 0.1 group; p > 0.05). In conclusion, these results indicate that serum Tg levels cannot be suppressed by maximal TSH suppression in tumor-free DTC patients. The suppression of TSH to less than 0.1 mU/L seems not to be necessary in most patients who have no evidence of active disease.

Immunoradiometric assay of thyroglobulin in patients with differentiated thyroid carcinomas: need for thyroglobulin recovery tests

As interference from thyroglobulin autoantibodies appears to have been overcome in new commercial thyroglobulin assays by the use of monoclonal antibodies, the need for thyroglobulin recovery tests became uncertain. Sera (n=45) from patients with differentiated thyroid carcinomas were selected on the basis of a thyroglobulin recovery value below 70% in the Dynotest Tg immunoradiometric assay (Brahms) routinely used in our laboratory. Serum thyroglobulin levels were then measured using three other commercial immunoradiometric assays: thyroglobulin ERIA (Pasteur), HTGK (Sorin) and ELSA HTG (Cis Bio International). Thyroglobulin autoantibodies were measured using the Thyrak assay (Brahms). Although many patients were thyroglobulin antibodies-negative (< 200 U/ml, n=26), most immunoradiometric assays failed to detect thyroglobulin in patients with evidence of recurrence. Low thyroglobulin values associated with low thyroglobulin recovery in thyroglobulin antibody-negative patients appear to be more biologically relevant than a single low thyroglobulin value, which can lead to lack of medical intervention. We conclude that the thyroglobulin recovery test is a prerequisite for the correct interpretation of serum thyroglobulin levels determined with immunoradiometric assays in the follow-up of thyroglobulin autoantibody-negative patients treated for differentiated thyroid carcinomas.

High-resolution ultrasound associated with aspiration biopsy in the follow-up of patients with differentiated thyroid cancer

OBJECTIVE: To assess the value of ultrasound in the follow-up of patients undergoing surgery for differentiated thyroid carcinoma.

SUBJECTS: The study included 89 patients (70 women and 19 men) with differentiated thyroid carcinoma (76 papillary and 13 follicular cancer).

METHODS: High-frequency ultrasound (US) was used in the evaluation of 89 subjects who underwent surgery for thyroid carcinoma. Fine-needle aspiration was performed in cases with positive US. In addition, determinations of thyroglobulin (Tgb) in serum, scintigraphy with 131I, and cervical palpation were evaluated. We determined sensitivity, specificity, and overall accuracy for each of these diagnostic methods.

RESULTS: Ultrasonography was positive in 22 subjects, 16 in the nodal area and 6 in the thyroid bed. Twenty-two subjects received fine-needle aspiration with US control; 13 (59%) of 22 were positive for cancer. The results of the US for detecting neoplastic disease showed a sensitivity of 65%, specificity of 86%, and overall accuracy of 82%. The overall accuracy for scintigraphy was 88% and for Tgb, 91%.

CONCLUSION: We concluded that US can be included in the follow-up protocol for patients undergoing surgery for differentiated cancer of thyroid, as a valuable tool to localize the recurrence. This technique is particularly useful in the evaluation of patients who are found to have elevated Tgb levels.

The treatment of differentiated thyroid cancer includes surgery and, in some cases, the ablation of residual thyroid tissue with therapeutic doses of iodine 131I. 1 The posttreatment search for recurrence or metastases is based on periodic body scanning with 131I and determination of serum thyroglobulin (Tgb) levels. 2,3

High-resolution ultrasound (US; 10 MHz) has been found to have a high sensitivity in diagnosing nonpalpable cervical masses. 4–6 Thus the possibility exists that including it in the protocols for follow-up of differentiated thyroid cancer may be valuable.

The aim of our study was to assess the value of high-resolution US (associated with directed fine-needle aspiration [FNA] biopsy) in the follow-up of patients undergoing surgery for papillary and follicular thyroid cancer.

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(+).

Thyroid cancer: a review of treatment and follow-up

The importance of thyroid cancers far exceeds their frequency, since they are uncommon tumours accounting for only 1% of all malignancies and for even smaller proportion of cancer deaths (0.2%). A variety of distinct tumour types arise in the thyroid gland, with variable natural histories resulting from different rates of growth and biological aggressiveness. The long natural history of the majority of thyroid neoplasms imposes a commitment for long-term follow-up and stresses the importance of planning treatment so as to avoid delayed complications that impair the quality of life of patients. The management of thyroid cancer is multidisciplinary, requiring consultation and active intervention by surgeons, endocrinologists and radiotherapists. Surgery is of paramount importance in the successful eradication of the tumours while radioiodine offers a unique therapeutic approach. Treatment must be strongly influenced by consideration of prognostic variables.

False positive 131I total body scan due to an ectasia of the common carotidis

A cervical accumulation of radioiodine at Total Body Scan (TBS) in a patient who had been thyroidectomized for a follicular thyroid carcinoma led to unnecessary radioiodine treatment. Thyroglobulin measurements indicated constantly low levels. Following ultrasound scanning of the neck, echo-doppler examination of the cervical vessels and angiography with 99Tc, this area of increased activity at TBS imaging was shown to be due to an ectasia of the right common carotidis causing blood stasis and reverse flow.

Metastatic thyroid carcinoma of the adrenal gland

Follicular thyroid carcinoma may spread distant metastases in sites such as bone, lung and brain. In our series of 448 patients with follicular thyroid carcinoma, distant metastases were present in 25% of cases. We report here a case of follicular thyroid carcinoma with a single metastasis at the right adrenal gland, that was found 12 years after total thyroidectomy and radioiodine therapy. Chest X ray, neck and liver echography and total body scan (TBS), performed after radioiodine therapy, were negative. During hormone therapy, serum thyroglobulin (Tg) levels were less than 1 ng/ml until 1990, and then Tg progressively increased in eighteen months up to 149 ng/ml. A new TBS was negative. At computer tomography a node at the right adrenal gland was found. The patient underwent adrenalectomy and histology showed a metastatic follicular thyroid cancer with Hurthle cells. After 1 and 5 months from surgery Tg serum levels were 0.9 ng/ml. This case shows once again the importance of Tg serum levels during follow-up of differentiated thyroid cancer.