Thyroglobulin antibody resolution after total thyroidectomy for cancer

Thyroglobulin Antibodies as a Prognostic Factor in Papillary Thyroid Carcinoma Patients with Indeterminate Response After Initial Therapy

The clinical outcome of papillary thyroid carcinoma (PTC) patients with an indeterminate response after initial therapy is reported to be intermediate, between incomplete and excellent responses. This study evaluated the outcomes of PTC patients with indeterminate response after initial therapy. It was further determined whether the indeterminate findings predicted outcomes more precisely. Patients were further classified into 3 groups based on risk of structural persistence/recurrence: Tg group: detectable thyroglobulin, negative antithyroglobulin antibody, regardless nonspecific imaging findings; TgAb group: positive antithyroglobulin antibody, regardless thyroglobulin levels and nonspecific imaging findings, and Image group: nonspecific findings on neck ultrasonography or faint uptake in the thyroid bed on whole-body scan, undetectable thyroglobulin and negative antithyroglobulin antibody. Sixty-six patients aged 44.1±12.7 years were studied, of whom 58 (87.9%) were females. All patients underwent total thyroidectomy, and 52 patients (78.8%) received radioiodine. After 5.7 years (P25-75 2.6-9.75 years) of follow-up, most patients (89.4%) were reclassified as having an excellent response or remained in the indeterminate response to therapy. Structural recurrence/persistence disease was detected in 7 (10.6%) patients. The persistence/recurrence rate in groups were as follow: Tg, 2.63%; TgAb, 31.25%; Image, 8.3% (p=0.007). The 10-years disease-free survival rate in the TgAb group was significantly reduced (p=0.022). Our results suggest that patients with PTC and indeterminate response due to positive serum antithyroglobulin antibody have more risk of development of structural disease. These findings suggest a more individualized follow-up strategy for patients with an indeterminate response.

Serum antithyroglobulin antibody levels are not a good predictive factor on detection of disease activity in patients with papillary thyroid carcinoma

Objective

Thyroglobulin antibodies (TgAb) are detected in thyroid cancer patients up to 25%. We investigated the prognostic value of TgAb positivity in patients with papillary thyroid carcinoma (PTC) after initial therapy.

Patients and Methods

A database of 109 consecutive patients who underwent total thyroidectomy and therapeutic lateral neck dissection followed by remnant ablation for PTC between January 1989 and December 2014 was reviewed We recorded the patients' all serum Tg and TgAb levels over time to establish changing trends. Patients were classified as either positive or negative according to serum TgAb levels. The recurrence or persistence rates in both groups were compared.

Results

Of the 109 patients enrolled 14 patients had TgAb positivity. Thirty-two (29.3%) showed disease recurrence or persistent disease during 101 months of follow-up. Twenty-seven of 95 patients (28.4%) with negative TgAb had persistent or recurrent disease, whereas 5 of 14 patients (35.7%) with positive TgAb had persistence or recurrence (P = 0.57). No significant difference in disease-free survival (115.3 ± 10.8 vs. 224.1 ± 16.6 months, P = 0.78) and overall survival (P = 0.59) was observed between TgAb positive and TgAb negative patients.

Conclusions

TgAb status is not useful as a prognostic and predictive factor for clinical outcomes in patients with PTC in our experience.

Individualized Follow-Up Strategy for Patients with an Indeterminate Response to Initial Therapy for Papillary Thyroid Carcinoma

BACKGROUND

The concept of a dynamic risk-stratification scheme has been suggested for individualized management of patients with papillary thyroid carcinoma (PTC). However, there is no specified follow-up strategy for patients with an indeterminate response.

METHODS

This study evaluated 403 PTC patients who had an indeterminate response during the first 12-24 months after initial therapy. All patients underwent total thyroidectomy with radioactive iodine remnant ablation. Patients were further classified into three groups based on risk of structural persistence/recurrence: a Tg+ group (detectable thyroglobulin [Tg], regardless of antithyroglobulin antibody [TgAb] or imaging findings; 196 patients), a TgAb+ group (positive results for TgAb with undetectable Tg, regardless of imaging findings; 46 patients), and an Image+ group (nonspecific findings on neck ultrasonography or faint uptake in the thyroid bed on whole-body scan, with undetectable Tg and negative results for TgAb; 161 patients).

RESULTS

With a median of 9.6 years (interquartile range 7.7-11.2 years) of follow-up, 56 (14%) PTC patients had structural persistent/recurrent disease: 50 (89%) at locoregional sites and six (11%) at distant sites. The recurrence rate in Tg+, TgAb+, and Image + groups were 26.5%, 8.7%, and 0%, respectively. The median time to detection of structural persistent/recurrent disease from the initial thyroid surgery was 3.7 years (interquartile range 2.5-6.3 years). The optimal cutoff stimulated Tg level to predict structural persistent/recurrent disease was 3.1 ng/mL in the Tg+ group. This classification system revealed higher predictability of structural persistent/recurrent disease than the tumor-node-metastasis staging system and American Thyroid Association risk stratification (proportion of variation explained: 15.7% vs. 2.4% and 0.9%, respectively). Six (3%) patients with distant metastatic disease were all classified in the Tg+ group, and all had lung metastasis.

CONCLUSIONS

The findings suggest a more individualized follow-up strategy for patients with an indeterminate response. More careful evaluation, including early evaluation of distant metastasis, is necessary in patients with elevated Tg levels. However, for patients testing positive for TgAb or those with only nonspecific imaging findings, regular follow-ups of Tg and TgAb levels and neck ultrasonography are sufficient.

Back so soon? Is early recurrence of papillary thyroid cancer really just persistent disease?

BACKGROUND

Papillary thyroid carcinoma has excellent survival, yet recurrence remains a challenge. We sought to determine the proportion of reoperations performed for persistent, rather than truly recurrent, disease.

METHODS

We conducted a retrospective review of a prospectively maintained database. Patients with papillary thyroid carcinoma who underwent reoperation for disease from 2000-2016 were included. We defined recurrence as disease that developed after a patient had an undetectable thyroglobulin and a negative ultrasonography within 1 year of operation.

RESULTS

A total of 69 patients underwent 92 reoperations. On initial pathology, mean tumor size was 2.6 cm, 51% were multifocal, and 42% had extrathyroidal extension. Half (46%) of the patients underwent a central/lateral neck dissection at the initial operation, and 77% were treated with postoperative radioactive iodine. The median time to first reoperation was 21 months (range, 1-292), and 42% occurred within 1 year. Only 3 operations met criteria for true "recurrence," while 71 operations were categorized as persistent disease.

CONCLUSION

Many reoperations for papillary thyroid carcinoma are for management of persistent disease. More than half of the patients required reoperation within the first 2 years, which suggests strongly that improvements in the preoperative assessment and adequacy of initial operative therapy need to be made to improve the care of patients with thyroid cancer.

Thyroglobulin Antibody Screen Prior to Mass Spectrometry Provides Measurable Cost Savings and Optimal Laboratory Utilization

OBJECTIVES

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods that allow accurate quantitation of thyroglobulin (Tg) in the presence of Tg antibodies (TgAbs) have recently become available. Due to cost differences between LC-MS/MS and immunoassay, some laboratories now offer a reflex test strategy that uses LC-MS/MS only for TgAb-positive samples. The goal of this study was to examine utilization of Tg testing strategies and cost savings.

METHODS

Test ordering patterns were examined for over 150,000 orders for TgAb and Tg in our laboratory. The average list price was determined from three separate commercial laboratories offering this testing.

RESULTS

Data showed that 89% of orders for Tg used the reflex test option, resulting in a savings of over $3 million compared with testing all samples by LC-MS/MS. Of the Tg by LC-MS/MS orders not using the reflex option, 1,663 also included a separate order for TgAb on the same patient sample, representing approximately $170,000 in potentially unnecessary costs from TgAb-negative samples.

CONCLUSIONS

Identifying situations to use more expensive testing methods (eg, LC-MS/MS) only when necessary, such as for TgAb-positive patients, leads to considerable cost savings and a more economical use of valuable health care resources.

Comparison of Antithyroglobulin Antibody Concentrations Before and After Ablation with 131I as a Predictor of Structural Disease in Differentiated Thyroid Carcinoma Patients with Undetectable Basal Thyroglobulin and Negative Neck Ultrasonography

BACKGROUND

Patients with differentiated thyroid carcinoma are submitted to a first assessment several months after initial therapy to evaluate their response to treatment. At that assessment, measurement of basal thyroglobulin (Tg) and antithyroglobulin antibodies (TgAb) and neck ultrasonography (US) are recommended. Serum Tg may be falsely negative in the presence of TgAb, and the management of patients with negative Tg but positive TgAb represents a challenge. The objective of this study was to correlate the variation in TgAb concentrations (comparison before and after ablation with (131)I) with the risk of structural disease.

METHODS

The sample consisted of 116 low- or intermediate-risk patients who had undetectable Tg, negative US at initial assessment, and positive TgAb 8-12 months after thyroidectomy and ablation with (131)I.

RESULTS

Comparison of TgAb concentrations before and after ablation with (131)I showed a reduction of >50% in 56 patients (group A), a reduction of <50% in 35 patients (group B), and an increase in 25 patients (group C). Metastases were detected in 5/116 (4.3%) patients during initial assessment (lymph nodes in two, pulmonary in two, and bone in one). They were diagnosed in 0/56, 2/35 (5.7%), and 3/25 (12%) patients of groups A, B, and C, respectively. During follow-up, metastases were detected in 7/111 (6.3%) patients (lymph nodes in six, and pulmonary in one). They occurred in 1/56 (1.8%), 3/33 (9%), and 3/22 (13.6%) patients of groups A, B, and C, respectively. Thus, structural disease was found in 1.8%, 14.3%, and 24% of groups A, B, and C, respectively. This rate was 4% in low-risk patients and 15.4% in intermediate-risk patients.

CONCLUSIONS

Among patients with undetectable Tg, negative US, and positive TgAb after ablation with (131)I, the frequency of structural disease was <5% in patients, with >50% reduction in TgAb. Among patients without a significant reduction in TgAb, approximately 10% of low-risk patients and >20% of intermediate-risk patients had structural disease. These results help define the indication for imaging methods other than US during initial assessment and long-term follow-up.