Prognostic Significance of Thyroglobulin Antibodies in Differentiated Thyroid Cancer

Predicting clinical outcomes of patients with serum thyroglobulin antibodies after thyroidectomy for differentiated thyroid cancer: a retrospective study from a UK regional center

BACKGROUND

Twenty-twenty-five percent of patients with differentiated thyroid cancer (DTC) can have elevated thyroglobulin antibodies (TgAb). The study aimed to find any prognostic significance of elevated TgAb during follow-up.

METHODS

Ten-year retrospective study from a tertiary center including 79 patients with raised TgAb after total/staged thyroidectomy for DTC. We identified patients with stable (7.6%), increasing (15%) and decreasing levels of TgAb (77.2%); groups 1, 2 and 3 respectively. During follow-up we analyzed TgAb in subcategories by TgAb trend (>50% rise, <50% rise, >50% decline, <50% decline, positive to negative/normalization, negative to positive and stable levels), gender, age, surgery, autoimmune disease, histology, RAI uptake, distant metastases, and recurrence.

RESULTS

The incidence of raised TgAb levels was 33.2%, with female predominance. No connection was identified regarding other parameters. 11.4% had distant metastases. The highest mean maximum levels of TgAb was in group 2 (1918.75 IU/mL) and the lowest in group 3 (412.70 IU/mL). The recurrence rate changed significantly between the 3 groups: 50% in group 1, 75% in group 2, and 25% in group 3 (P=0.002). Recurrence rates decreased to 15% in the subcategory where TgAb became negative/normal from positive (P=0.0001). In patients with a negative to positive TgAb level trend or >50% rise, recurrence rates were 100% (P=0.041) and 70% (P=0.012) respectively.

CONCLUSIONS

Patients with increasing TgAb levels during follow-up have a higher rate of recurrence, distinctly for those with negative to positive trend and >50% rise in TgAb. These patients need closer follow-up, and TgAb may be used as a dynamic follow-up marker.

Laboratory Thyroid Tests: A Historical Perspective

Background: This review presents a timeline showing how technical advances made over the last seven decades have impacted the development of laboratory thyroid tests. Summary: Thyroid tests have evolved from time-consuming manual procedures using isotopically labeled iodine as signals (¹³¹I and later ¹²⁵I) performed in nuclear medicine laboratories, to automated nonisotopic tests performed on multianalyte instruments in routine clinical chemistry laboratories. The development of isotopic radioimmunoassay techniques around 1960, followed by the advent of monoclonal antibody technology in the mid-1970s, led to the development of a nonisotopic immunometric assay methodology that forms the backbone of present-day thyroid testing. This review discusses the development of methods for measuring total thyroxine and triiodothyronine, direct and indirect free thyroid hormone measurements and estimates (free thyroxine and free triiodothyronine), thyrotropin (TSH), thyroid autoantibodies (thyroperoxidase, thyroglobulin [Tg] and TSH receptor autoantibodies), and Tg protein. Despite progressive improvements made in sensitivity and specificity, current thyroid tests remain limited by between-method differences in the numeric values they report, as well as nonspecific interferences with test reagents and interferences from analyte autoantibodies. Conclusions: Thyroid disease affects ∼10% of the U.S. population and is mostly managed on an outpatient basis, generating 60% of endocrine laboratory tests. In future, it is hoped that interferences will be eliminated, and the standardization/harmonization of tests will facilitate the establishment of universal test reference ranges.

Outcomes of Papillary Thyroid Microcarcinoma Presenting with Palpable Lateral Lymphadenopathy

Purpose: Papillary thyroid microcarcinoma (PTMC) is typically indolent in nature, allowing management with active surveillance protocols. Occasionally, a more aggressive phenotype can present and may lead to poor outcomes such as patients presenting with clinically significant lateral lymphadenopathy (cN1b). Prior analysis of the outcomes of this cohort is largely from papillary thyroid cancer (PTC) (>1 cm) or from institutions where use of radioactive iodine (RAI) is limited. Hence, we aim to describe the outcomes of patients with PTMC who presented with palpable cN1b disease, treated with total thyroidectomy and RAI. Methodology: We performed a retrospective cohort study. Outcomes of patients with PTMC who presented with palpable lateral lymph node (LN) metastases (microPTC cN1b) treated between 1997 and 2020 at Royal North Shore Hospital were compared with two control groups' outcomes: patients with clinically detected PTMC without evidence of involved LNs (microPTC cN0) and with larger PTC (>10 mm) who presented with palpable lateral lymphadenopathy (larger PTC cN1b). We assessed clinicopathological variables, postoperative risk stratification, rates of disease recurrence, reoperative surgery, and structural disease-free survival (DFS). Results: In total, 1534 PTMCs were diagnosed following thyroid surgery in the study period; of these, 157 (10%) were clinically detected microPTC cN0 and 26 microPTC cN1b (1.7%). There were 138 patients in the larger PTC cN1b control group. All cN1b patients were treated with total thyroidectomy and adjuvant RAI. Mean size of the largest LN deposit was similar between the microPTC cN1b and larger PTC cN1b groups (23 vs. 27 mm, p = 0.11). Patients with microPTC cN1b were more likely to have biochemical or structural persistence or recurrence compared with microPTC cN0 (19%, 5/26 vs. 3.8%, 6/157, p = 0.002) but less likely than larger PTC cN1b patients (19%, 5/26 vs. 42%, 58/138, p = 0.04). All patients in the microPTC cN1b group who had an excellent response to initial therapy (85%, 22/26) were disease free at last follow-up. The rate of reoperation was similar for the microPTC cN1b and microPTC cN0 groups (4%, 1/26 vs. 2%, 3/157, p = 0.461) and significantly lower than the larger PTC cN1b group (4%, 1/26 vs. 26%, 36/138, p = 0.002). Five-year DFS estimates were significantly better for microPTC cN1b patients than for larger PTC cN1b patients (94% vs. 59%, p = 0.001). Conclusions: MicroPTC cN1b patients treated with thyroidectomy and adjuvant RAI have inferior clinical outcomes compared with microPTC cN0 patients but have better outcomes than their larger PTC cN1b counterparts with respect to disease persistence and recurrence. Response to initial therapy provides valuable prognostication in microPTC cN1b patients: if these patients had an excellent response to initial treatment, they achieved long-term DFS in this series.

An immediate postoperative response to therapy assessment can help avoid unnecessary RAI therapy

Background

Radioiodine (RAI) therapy plays a vital role in the postoperative treatment of differentiated thyroid cancer (DTC) patients underwent total thyroidectomy (TT). However, even in the presence of capsular invasion and lymph node metastasis prognosis can be excellent and a postoperative RAI treatment might not be necessary for all patients. Therefore, this study explored the criteria for avoiding unnecessary RAI therapy in these patients.

Method

We applied response to therapy assessment immediately after surgery and prospectively recruited 179 excellent or indeterminate response DTC patients with capsular invasion and/or LNM who underwent TT without RAI therapy. During the follow-up, thyroglobulin (Tg), thyroglobulin antibody (TgAb) levels, and cervical ultrasonography were collected and analyzed. Disease-free survival (DFS) was calculated using the Kaplan-Meier method. In addition, response to therapy assessments was performed on patients during each follow-up.

Results

The mean follow-up period was 29.85 ± 17.44 months, and the 3- and 5-year DFS for all the patients was 99.3% in each. At the last follow-up, 165 (92.2%) patients had excellent responses, while 12 (6.7%) had an indeterminate response, and one (0.6%) each had biochemical and incomplete responses. No significant difference was observed in response to therapy between the subgroups of LNM and tumor invasion (P>0.05). For patients with capsular invasion and a number of metastatic lymph nodes ≤5 and >5, the proportions of recorded excellent responses were 95.9%, 91.0%, and 85.7%, respectively. Better responses were observed in females (excellent response: 95.5%, P=0.023), patients with stimulated Tg (s-Tg) ≤1ng/ml (excellent response: 100%, P<0.001), s-Tg ≤ 2ng/ml (excellent response: 98.4%, P<0.001), and excellent response for the immediate postoperative assessment (excellent response: 98.5%, P=0.004).

Conclusions

The current study suggested that the response to therapy assessment immediately applied postoperatively could help avoid unnecessary RAI therapy among DTC patients with capsular invasion and/or LNM. Moreover, excellent response patients and patients with indeterminate response and s-Tg ≤ 2ng/ml could be managed without RAI therapy.

The Autoantibodies against Tumor-Associated Antigens as Potential Blood-Based Biomarkers in Thyroid Neoplasia: Rationales, Opportunities and Challenges

The Autoantibodies targeting Tumor-Associated Antigens (TAA-AAbs) emerge as a result of a variety of tumor-related immunogenic stimuli and may be regarded as the eyewitnesses to the anti-tumor immune response. TAA-AAbs may be readily detected in peripheral blood to unveil the presence of a particular TAA-expressing tumor, and a fair number of TAAs eliciting the tumor-associated autoantibody response have been identified. The potential of TAA-AAbs as tumor biomarkers has been extensively studied in many human malignancies with a major influence on public health; however, tumors of the endocrine system, and, in particular, the well-differentiated follicular cell-derived thyroid neoplasms, remain understudied in this context. This review provides a detailed perspective on and legitimate rationales for the potential use of TAA-AAbs in thyroid neoplasia, with particular reference to the already established diagnostic implications of the TAA-AAbs in human cancer, to the windows for improvement and diagnostic niches in the current workup strategies in nodular thyroid disease and differentiated thyroid cancer that TAA-AAbs may successfully occupy, as well as to the proof-of-concept studies demonstrating the usefulness of TAA-AAbs in thyroid oncology, particularly for the pre-surgical discrimination between tumors of different malignant potential in the context of the indeterminate results of the fine-needle aspiration cytology.

Anti-Cancer Auto-Antibodies: Roles, Applications and Open Issues

Auto-antibodies are classically associated with autoimmune diseases, where they are an integral part of diagnostic panels. However, recent evidence is accumulating on the presence of auto-antibodies against single or selected panels of auto-antigens in many types of cancer. Auto-antibodies might initially represent an epiphenomenon derived from the inflammatory environment induced by the tumor. However, their effect on tumor evolution can be crucial, as is discussed in this paper. It has been demonstrated that some of these auto-antibodies can be used for early detection and cancer staging, as well as for monitoring of cancer regression during treatment and follow up. Interestingly, certain auto-antibodies were found to promote cancer progression and metastasis, while others contribute to the body's defense against it. Moreover, auto-antibodies are of a polyclonal nature, which means that often several antibodies are involved in the response to a single tumor antigen. Dissection of these antibody specificities is now possible, allowing their identification at the genetic, structural, and epitope levels. In this review, we report the evidence available on the presence of auto-antibodies in the main cancer types and discuss some of the open issues that still need to be addressed by the research community.

Antithyroglobulin Antibody Variation During Follow-Up Has a Good Prognostic Value for Preoperative Antithyroglobulin Antibody-Positive Differentiated Thyroid Cancer Patients: A Retrospective Study in Southwest China

OBJECTIVE

Antithyroglobulin antibody (TgAb) is a potential tumour marker for detecting differentiated thyroid cancer (DTC) recurrence, but insufficient data have supported its clinical applications. Our study aimed to describe the changing trend of TgAb after surgery and identify the relationship between this trend and clinical outcomes.

PATIENTS AND METHODS

We reviewed the electronic records of 1,686 DTC patients who had undergone total thyroidectomy (TT) and radioactive iodine (¹³¹I) therapy at West China Hospital of Sichuan University from January 2015 to December 2017. Finally, 289 preoperative TgAb-positive DTC patients were included and divided into four subgroups depending on the clinical outcome: Group A (tumour free), Group B (uncertain), Group C (incomplete biochemical response), and Group D (structural disease). The patient demographics, tumour characteristics, operations, pathology reports, and all serological biomarkers were reviewed and compared, and the prognostic efficacy of TgAb was evaluated.

RESULTS

Among all 1,686 patients, 393 (23.65%) were TgAb positive (>40 IU/ml) preoperatively. The TgAb level in Group A decreased significantly after surgery and ¹³¹I therapy and stabilised at a low level after 1-2 years of ¹³¹I therapy. However, in the other three groups, the decrease in TgAb was not significant after treatment. Conversely, TgAb declined slowly and remained stable or increased. The variations in TgAb relative to the preoperative level of Group A were significantly larger than those of Groups B, C, and D at most time points of follow-up (p < 0.001). By receiver operating characteristic (ROC) analyses, the variations of TgAb > -77.9% at 6 months after ¹³¹I therapy (area under the curve (AUC) = 0.862; p < 0.001) and TgAb > -88.6% at 2 years after ¹³¹I therapy (AUC = 0.901; p < 0.001) had good prognostic efficacy in tumour-free survival. When the variation in TgAb > -88.6% at 2 years after ¹³¹I therapy was incorporated as a variable in the American Thyroid Association (ATA) categories, both intermediate- and high-risk patients also had a significantly increased chance of being tumour free (from 75.68% to 93.88% and 42.0% to 82.61%, respectively).

CONCLUSIONS

For preoperative TgAb-positive DTC patients, variations in TgAb > -77.9% at 6 months after ¹³¹I therapy and TgAb > -88.6% at 2 years after ¹³¹I therapy had good prognostic efficacy. Their incorporation as variables in the ATA risk stratification system could more accurately predict disease-free survival.