Effectiveness of Peripheral Thyrotropin Receptor mRNA in Follow-Up of Differentiated Thyroid Cancer

Assessment of the utility of measuring Thyroglobulin mRNA levels by Quantitative Real-Time PCR in the follow-up of differentiated thyroid cancer patients

INTRODUCTION

The determination of thyroglobulin levels by immunoassay and imaging studies is subject to interference by antithyroglobulin antibodies in up to 30% of cases, suggesting a need to find alternative methods for the follow-up of a significant number of thyroid cancer patients.

OBJECTIVES

Assess the sensitivity, specificity, and predictive values of thyroglobulin messenger RNA levels measured by quantitative Real Time-PCR (qRT-PCR) in the blood of patients followed for differentiated thyroid cancer.

METHODS

This is a prospective study of Tg-mRNA levels measured with qRT-PCR. A peripheral blood sample was taken in patients with excellent response (69) and with structural incomplete response to treatment (23). Results were analysed using the Unity Real-Time program and expressed as fg/μg RNA. A Receiver Operating Characteristic curve was constructed to assess Tg-mRNA cut-off values.

RESULTS

Tg-mRNA levels were not significantly different between the group with excellent response [0.10 fg/μg RNA (0.08-0.17)] and the group with incomplete structural response [0.133 fg/μg RNA (0.07-0.33)] (P < .06). Test sensitivity was 69.6%, specificity was 59.4%, negative predictive value was 85.4% and positive predictive value 36.4% CONCLUSIONS: Our experience shows that this technique could be useful as a rule-out test in selected cases, but its low sensitivity and specificity preclude its usefulness as a first-line test.

Assessment of the utility of measuring Thyroglobulin mRNA levels by Quantitative Real-Time PCR in the follow-up of differentiated thyroid cancer patients

INTRODUCTION

The determination of thyroglobulin (Tg) levels by immunoassay is subject to interference by antithyroglobulin antibodies in up to 30% of cases, suggesting a need to find alternative methods for the follow-up of a significant number of thyroid cancer patients.

OBJECTIVES

Assess the sensitivity, specificity, and predictive values of thyroglobulin messenger RNA (Tg-mRNA) levels measured by quantitative Real Time-PCR (qRT-PCR) in the blood of patients followed for differentiated thyroid cancer.

METHODS

This is a prospective study of Tg-mRNA levels measured with qRT-PCR. A peripheral blood sample was taken in patients with excellent response (n=69) and with structural incomplete response to treatment (n=23). Results were analysed using the Unity Real-Time program and expressed as fg/μg RNA. A Receiver Operating Characteristic curve was constructed to establish Tg-mRNA cut-off values.

RESULTS

Tg-mRNA levels were not significantly different between the group with excellent response [0.10fg/μg RNA (0.08-0.17)] and the group with incomplete structural response [0.133fg/μg RNA (0.07-0.33)] (p<0.06). Test sensitivity was 69.6%, specificity was 59.4%, negative predictive value was 85.4% and positive predictive value was 36.4%.

CONCLUSIONS

Our experience shows that this technique could be useful as a rule-out test in selected cases, but its low sensitivity and specificity preclude its usefulness as a first-line test.

Circulating thyroid stimulating hormone receptor messenger RNA and differentiated thyroid cancer: A diagnostic meta-analysis

Thyroid stimulating hormone receptor messenger RNA (TSHR-mRNA) is over-expressed in thyroid cancer patients, which indicates that TSHR-mRNA is a potential biomarker of thyroid cancer. However, system evaluation for TSHR-mRNA as a diagnostic biomarker of thyroid cancer is deficient. The performance of TSHR-mRNA for thyroid cancer diagnosis was evaluated in this study. Three common international databases as well as a Chinese database were applied for literature researching. Quality assessment of the included literatures was conducted by the QUADAS-2 tool. Totally, 1027 patients from nine studies eligible for the meta-analysis were included in this study. Global sensitivity and specificity for the positivity of TSHR-mRNA in the thyroid cancer diagnosis is 72% and 82%. The value of AUC for this test performance was 0.84. Our meta-analysis suggests that TSHR-mRNA might be a potential biomarker to complete present diagnostic methods for early and precision diagnosis of thyroid cancer. Notably, this findings need validation thorough large-scale clinical studies.

CIRCULATING TUMOR CELLS IN MINIMALLY INVASIVE FOLLICULAR THYROID CARCINOMA AND BENIGN THYROID TUMORS WITH A FOLLICULAR PATTERN: PILOT EXPERIENCE

Purpose

Minimally invasive follicular thyroid carcinomas (MIFCs) are uncommon; literature offers limited guidance on their natural history and management. Starting January 2015 we measured circulating tumor cells (CTCs) in patients with MIFC (n=22) or benign thyroid tumors with follicular features (n=4).

Methods

In a retrospective analysis, we assessed detectability of and serial changes in CTC, compared demographic/clinical differences between CTC-positive versus CTC-negative subgroups using Student's t-test, and examined correlations between CTC status and serum thyroglobulin using Spearman's test. CTCs were quantitated via immunomagnetic separation/microscopic inspection.

Results

Thirteen patients (50%: 12/22 MIFC, 1/4 benign tumor) were initially CTC-positive; 3 remained CTC-positive in ≥1 subsequent measurement. CTC-positive patients had larger tumors and more frequent multifocality and vascular invasion versus CTC-negative patients (n=13). However, no tested variable differed significantly between the subgroups. After 17.2±10.5 months, neither subgroup showed evidence of disease. Significant correlation was absent (p ≥ 0.263) between CTC and Tg negativity (r = 0.243; n=13 evaluable) or initial CTC positivity and Tg positivity (r = -0.418; n=9 evaluable).

Conclusions

In the studied settings, CTC measurement is feasible, has unclear clinical/outcome implications, but may provide different information versus thyroglobulin testing. Lengthier assessment is warranted in larger series.

Circulating tumor cells in thyroid carcinoma - the prognostic role of this biomarker. Review of the literature

Thyroid cancer is a disease with a good prognosis and high survival rates, but having a marked growth of incidence all over the world in the last years. This fact requires special attention of researchers for understanding the behavior of this disease and to establish a correct therapy. Analysis of circulating tumor cells in patients with different malignancies is nowadays a new and exciting research tool, which can improve the diagnosis and prevent the metastatic disease. In the case of thyroid carcinoma there are few studies which explore these biomarkers and investigate the prognostic significance of circulating tumor cells. With this review we seek to emphasize the role of these cells to better understand the mechanisms of invasion or metastasis and to establish a new research base to treat aggressive forms of this type of cancer. Most of the included studies demonstrate the efficacy of these markers for diagnosis and follow up.

Circulating thyrotropin receptor messenger ribonucleic acid is not an effective marker in the follow-up of differentiated thyroid carcinoma

Background

Circulating thyrotropin receptor messenger ribonucleic acid (TSHR mRNA) assay has been validated in the follow-up of differentiated thyroid carcinoma (DTC) because of its high sensitivity during thyroid hormone therapy and no interference with endogenous anti-thyroglobulin antibodies (TgAb) compared to serum thyroglobulin (Tg). We investigated the efficacy of TSHR mRNA assay in 160 DTC patients using quantitative PCR (qPCR).

Findings

Only TSHR mRNA level of structural persistent disease with TgAb-positive (3.47 (2.97–9.53) pg equivalents/μg total RNA; p = 0.013) and its subgroup of distant metastasis patients with TgAb-positive (5.55 (3.28–12.52) pg equivalents/μg total RNA; p = 0.009) were significantly different from patients with no evidence of disease (2.32 (1.44–3.94) pg equivalents/μg total RNA). Applying cutoff at 2.00 pg equivalents/μg total RNA enabled us to predict structural persistent disease patients with a sensitivity of 62.3 % and a specificity of 42.9 %. Although, the sensitivity of TSHR mRNA assay in TgAb-postive patients (88.2 %) was superior than serum Tg (47.1 %) (p = 0.00002), the accuracy of the test is only 54.5 %.

Conclusions

This study demonstrated that TSHR mRNA assay has good sensitivity in TgAb-positive patients but it is neither specific enough as a first-line of testing nor a surrogate marker in the follow-up of our DTC patients.

Thyroglobulin antibody levels do not predict disease status in papillary thyroid cancer

BACKGROUND

Thyroglobulin antibodies (TgAb) are present in approximately 20% of patients with papillary thyroid cancer (PTC) and invalidate the serum thyroglobulin (Tg) level as a tumour marker. We examined whether trends in the TgAb level could serve as a surrogate marker of disease status in the surveillance of patients with PTC.

METHODS

All patients found to have a least one positive postoperative TgAb level (determined by the Beckman-Coulter Access Assay) after undergoing initial surgery for PTC from 2000 to 2010 at a single institution were included. Log-log transformation and linear regression were applied to longitudinal TgAb levels, yielding patient-specific regression coefficients that categorized as follows: highly negative, moderately negative and positive/no trend. The recurrence rate in each category was then assessed.

RESULTS

Ninety-three of 967 patients with PTC were included. Recurrent disease was detected in 19 patients (20%) after a mean follow-up time of 51 months. Regression coefficients in the highly negative and moderately negative groups were not different, and hence these groups were pooled. The proportion of recurrent cases in the negative trend group was similar to that in the positive/no trend group (19.7% vs 21.9%, NS). The mean regression coefficients were similar for recurrent and nonrecurrent cases within both the negative trend group (-0.89 vs -0.80, NS) and the positive/no trend group (0.08 vs 0.33, NS).

CONCLUSION

Trends in the TgAb level do not predict disease status in PTC in our experience. In the context of most commercially available TgAb assays, surveillance of TgAb-positive patients will hinge on high-quality imaging until a valid alternative serum marker to Tg is identified.

Objective assessment of cancer genes for drug discovery

Selecting the best targets is a key challenge for drug discovery, and achieving this effectively, efficiently and systematically is particularly important for prioritizing candidates from the sizeable lists of potential therapeutic targets that are now emerging from large-scale multi-omics initiatives, such as those in oncology. Here, we describe an objective, systematic, multifaceted computational assessment of biological and chemical space that can be applied to any human gene set to prioritize targets for therapeutic exploration. We use this approach to evaluate an exemplar set of 479 cancer-associated genes, reveal the tension between biological relevance and chemical tractability, and describe major gaps in available knowledge that could be addressed to aid objective decision-making. We also propose drug repurposing opportunities and identify potentially druggable cancer-associated proteins that have been poorly explored with regard to the discovery of small-molecule modulators, despite their biological relevance.

Measurement of calcitonin and calcitonin gene-related peptide mRNA refines the management of patients with medullary thyroid cancer and may replace calcitonin-stimulation tests

BACKGROUND

Serum calcitonin (sCT) is the main tumor marker for medullary thyroid cancer (MTC), but it has certain limitations. Various sCT assays may have important intra-assay or interassay variation and may yield different and sometimes conflicting results. A pentagastrin- or calcium-stimulation calcitonin (CT) test may be desirable in some situations. Alternatively, or in the absence of the stimulation test, mRNA detection offers the advantages of being more comfortable and less invasive; it only requires blood collection and has no side effects. The objective of this study was to investigate the applicability of measuring calcitonin-related polypeptide alpha (CALCA) gene transcripts (CT-CALCA and calcitonin gene-related peptide [CGRP]-CALCA) in patients with MTC and in relatives diagnosed with a RET mutation and to test mRNA as an alternative diagnostic tool for the calcitonin-stimulation test.

METHODS

Twenty-three healthy controls and 26 individuals evaluated for MTC were selected, including patients with sporadic or hereditary MTC and RET mutation-carrying relatives. For molecular analysis, RNA was extracted from peripheral blood, followed by cDNA synthesis using 3.5 μg of total RNA. Quantitative real-time polymerase chain reaction (RT-qPCR) was performed with SYBR Green and 200 nM of each primer for the two specific mRNA targets (CT-CALCA or CGRP-CALCA) and normalized with the ribosomal protein S8 as the reference gene.

RESULTS

We detected CALCA transcripts in the blood samples and observed a positive correlation between them (r=0.946, p<0.0001). Both mRNAs also correlated with sCT (CT-CALCA, r=0.713, p<0.0001; CGRP-CALCA, r=0.714, p<0.0001). The relative expression of CT-CALCA and CGRP-CALCA presented higher clinical sensitivity (86.67 and 100, respectively), specificity (97.06 and 97.06), positive predictive value (92.86 and 93.75), and negative predictive value (94.29 and 100), than did sCT (73.33, 82.35, 64.71, and 87.50, respectively). In addition, the CALCA transcript measurement mirrored the response to the pentagastrin test.

CONCLUSION

We demonstrate that the measurement of CALCA gene transcripts in the bloodstream is feasible and may refine the management of patients with MTC and RET mutation-carrying relatives. We propose considering the application of this diagnostic tool as an alternative to the calcitonin-stimulation test.

Overview of molecular biomarkers for enhancing the management of cytologically indeterminate thyroid nodules and thyroid cancer

OBJECTIVE

To provide information on molecular biomarkers that can help assess cytologically indeterminate thyroid nodules.

METHODS

Published studies on immunohistologic, somatic mutation, gene expression classifier, microRNA, and thyrotropin receptor messenger RNA biomarkers are reviewed, and commercially available molecular test panels are described.

RESULTS

Thyroid nodules are common, and clinical guidelines delineate an algorithmic approach including serum thyroid-stimulating hormone measurement, diagnostic ultrasound examination, and, when appropriate, fine-needle aspiration (FNA) biopsy for determination of a benign versus malignant status. In clinical practice, approximately 20% of FNA-derived cytology reports are classified as "indeterminate" or follicular nodules that do not fulfill either benign or malignant criteria. In this setting, the actual risk for malignancy of a cytologically indeterminate nodule ranges from approximately 15% to 34%. Research describing molecular biomarkers from thyroid cancer tissue has been applied to FNA-derived thyroid nodule material. There is also a serum molecular marker that has been reported with goals similar to those for the FNA-derived molecular markers: to enhance the preoperative diagnosis of thyroid cancer and reduce the large number of patients who have a diagnostic surgical procedure for benign thyroid nodules.

CONCLUSION

Progress toward the foregoing goals has been made and continues to evolve with the recent appearance of molecular biomarker tests that can be selectively applied for further assessment of cytologically indeterminate thyroid nodules.

Recovering circulating extracellular or cell-free RNA from bodily fluids

The presence of extracellular circulating or cell-free RNA in biological fluids is becoming a promising diagnostic tool for non invasive and cost effective cancer detection. Extracellular RNA or miRNA as biological marker could be used either for the early detection and diagnosis of the disease or as a marker of recurrence patterns and surveillance. In this review article, we refer to the origin of the circulating extracellular RNA, we summarise the data on the biological fluids (serum/plasma, saliva, urine, cerebrospinal fluid and bronchial lavage fluid) of patients suffering from various types of malignancies reported to contain a substantial amount of circulating extracellular (or cell-free) RNAs and we discuss the appropriate reagents and methodologies needed to be employed in order to obtain RNA material of high quality and integrity for the majority of the experimental methods used in RNA expression analysis. Furthermore, we discuss the advantages and disadvantages of the RT-PCR or microarray methodology which are the methods more often employed in procedures of extracellular RNA analysis.

Summary statement: utility of molecular marker testing in thyroid cancer

The use of molecular markers for thyroid cancer diagnosis, prognosis, and surveillance have been an exciting area of study and change. Recent investigative focus on promising new markers will very likely lead to improvements in the diagnostic utility of fine needle aspiration biopsy (FNAB) in predicting malignancy, as well as provide more accurate prognostic information pre- and postoperatively. The 2010 Annual Meeting of the American Association for Endocrine Surgeons featured a symposium dedicated to molecular marker testing in thyroid cancer and its potential clinical applicability.

Blood thyroglobulin and TSH receptor mRNA detection by RT-PCR in the follow-up of differentiated thyroid cancer patients

OBJECTIVE

During the last years several groups have used the technique of RT-PCR for the detection of circulating thyroid cells, through the amplification of thyroglobulin (Tg) and TSH receptor(TSH-R) mRNA; however the published results are controversial. In this study we investigated the utility for the detection of Tg and TSH-R mRNA by RT-PCR in patients with differentiated thyroid cancer (DTC) during treatment with levothyroxine.

SUBJECTS AND METHODS

We investigated the expression of Tg and TSH-R mRNA by single and nested RT-PCR in the blood of 3 groups of subjects: (A) 34 patients with DTC and no evidence of disease, (B) 8 patients with DTC and evidence of local or distant metastasis and (C) 13 normal subjects. Expression levels of Tg mRNA were also analysed by comparative semi-quantitative RT-PCR.

RESULTS

Tg and TSH-R mRNA signals were detected in all subjects (patients with DTC with and without evidence of disease and in normal subjects) by single or nested RT-PCR. By semi-quantitative RT-PCR and densitometric analysis of PCR products, mean levels of circulating Tg mRNA of the 3 groups were: Group A 0.182+/-0.107, Group B 0.329+/-0.298 and Group C 0.305+/-0.217.

CONCLUSIONS

Single or nested RT-PCR for Tg and TSH-R mRNA is not a suitable tool in the follow-up of patients with DTC. Lower levels of Tg mRNA in patients with DTC without evidence of disease, although not significant, may indicate that small numbers of thyroid cells may be normally present in the circulation or may represent an ectopic transcription of messengers from blood cells.