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

Deciphering pathological behavior of pediatric medullary thyroid cancer from single-cell perspective

Background

Pediatric medullary thyroid cancer (MTC) is one of the rare pediatric endocrine neoplasms. Derived from C cells of thyroid glands, MTC is more aggressive and more prompt to metastasis than other types of pediatric thyroid cancer. The mechanism remains unclear.

Methods

We performed single-cell transcriptome sequencing on the samples of the primary tumor and metastases lymph nodes from one patient diagnosed with MTC, and it is the first single-cell transcriptome sequencing data of pediatric MTC. In addition, whole exome sequencing was performed and peripheral blood was regarded as a normal reference. All cells that passed quality control were merged and analyzed in R to discover the association between tumor cells and their microenvironment as well as tumor pathogenesis.

Results

We first described the landscape of the single-cell atlas of MTC and studied the interaction between the tumor cell and its microenvironment. C cells, identified as tumor cells, and T cells, as the dominant participant in the tumor microenvironment, were particularly discussed in their development and interactions. In addition, the WES signature of tumor cells and their microenvironment were also described. Actively immune interactions were found, indicating B cells, T cells and myeloid cells were all actively participating in immune reaction in MTC. T cells, as the major components of the tumor microenvironment, proliferated in MTC and could be divided into clusters that expressed proliferation, immune effectiveness, and naive markers separately.

A Triumvirate:: Correlating Thyroid Cytopathology, Molecular Testing, and Histopathology

Risk stratification is essential in the preoperative evaluation and management of thyroid nodules, most of which are benign. Advances in DNA and RNA sequencing have shed light on the molecular drivers of thyroid cancer. Molecular testing of cytologically indeterminate nodules has helped refine risk stratification, triage patients for surgery, and determine the extent of surgery. Molecular platforms with high negative predictive values can help identify nodules that may be spared surgery and can be managed conservatively. Here we discuss the importance of integrating cytomorphologic, molecular, and histologic features to help avoid errors and improve patient management.

Circulating Biomarkers in Thyroid Cancer

Thyroid cancer is the most important endocrine cancer with increasing incidence. While thyroid cancers, especially papillary thyroid cancers, are known to exhibit generally a favorable outcome with excellent survival rates, some thyroid cancers are more aggressive with a poor prognosis. Several different biomarkers have been introduced for the diagnosis of disease, identification of tumor load, assessment of therapy response, and the detection of recurrence during follow-up of the thyroid cancer patients. This chapter gives a brief overview of the circulating biomarkers used in thyroid cancer patients.

Preoperative Serum Calcitonin Level and Ultrasonographic Characteristics Predict the Risk of Metastatic Medullary Thyroid Carcinoma: Functional Analysis of Calcitonin-Related Genes

Background. Early cervical lymph node (LN) metastasis is an important cause of poor survival in patients with medullary thyroid cancer (MTC). This study evaluated whether the preoperative serum calcitonin level in combination with ultrasonographic features of MTC can be used to assess the LN status as well as predict the risk of metastasis in patients with MTC. Methods. We retrospectively analyzed the clinical data of 95 patients with MTC, and a nomogram model was constructed and validated. Using integrated database analysis of The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx), we mined pathways wherein CALCA is involved, identified calcitonin-related genes, and analyzed their functions. Results. Correlation analysis revealed a significant association between the infiltrating range, diameter, calcification, blood flow, the preoperative serum calcitonin level, and metastasis. The metastasis risk-prediction model showed great accuracy in determining the risk of metastasis in MTC (area under the curve of the receiver operating characteristic [ROC] curve: 0.979 [95% confidence interval 0.946–1.000]). Decision curve analysis (DCA) showed that the model has excellent clinical utilization potential. Significantly, CALCA, the mRNA for calcitonin, was highly expressed in thyroid cancer tissues and associated with the cytokine–cytokine receptor and neuroactive ligand-receptor interaction pathways as well as the cell-adhesion molecules. ROC curve indicated that the CNTFR, CD27, GDF6, and TSLP genes, which are related to the cytokine–cytokine receptor interaction pathway, could indicate the risk of metastasis in MTC. Conclusions. The preoperative serum calcitonin level, in combination with ultrasonographic features, can be used to predict the risk of metastasis in patients with MTC and constitute a noninvasive accurate method for preoperative diagnosis of MTC.

Calcitonin: current concepts and differential diagnosis

Calcitonin (CT) is most effectively produced by the parafollicular cells of the thyroid gland. It acts through the calcitonin receptor (CTR), a seven-transmembrane class II G-protein-coupled receptor linked to multiple signal transduction pathways with its main secretagogues being calcium and gastrin. It is clinically used mostly in the diagnosis and follow-up of medullary thyroid carcinoma (MTC). Hypercalcitoninemia can be attributed to primary (e.g. CT-secreting tumor) or secondary (e.g. due to hypercalcemia) overproduction, underexcretion (e.g. renal insufficiency), drug reaction (e.g. β-blockers), or false-positive results. In clinical practice, elevated basal calcitonin (bCT) is indicative, but not pathognomonic, of MTC. Current literature leans toward an age as well as gender-specific cutoff approach. bCT >100 pg/ml has up to 100% positive prognostic value (PPV) for MTC, whereas bCT between 8 and 100 pg/ml for adult males and 6 and 80 pg/ml for adult females should be possibly further investigated with stimulation calcitonin (sCT) tests. Calcium is showing similar efficacy with pentagastrin (Pg) sCT; however, the real value of these provocative tests has been disputed given the availability of new, highly sensitive CT immunoassays. Anyhow, evidence concludes that sCT <2 times bCT may not be suggestive of MTC, in which case, thyroid in addition to whole body workup based on clinical evaluation is further warranted. Moreover, measurement of basal and stimulated procalcitonin has been proposed as an emerging concept in this clinical scenario. Measuring bCT levels in patients with thyroid nodules as a screening tool for MTC remains another controversial topic. It has been well established, though, that bCT levels raise the sensitivity of FNAB (Fine Needle Aspiration Biopsy) and correlate with disease progression both pre- and postoperatively in this situation. There have been numerous reports about extrathyroidal neoplasms that express CT. Pancreatic, laryngeal, and lung neuroendocrine neoplasms (NENs) are most frequently associated with hypercalcitoninemia, but CT production has also been described in various other neoplasms such as duodenal, esophageal, cutaneous, and paranasal NENs as well as prostate, colon, breast, and lung non-NENs. This review outlines the current biosynthetic and physiology concepts about CT and presents up-to-date information regarding the differential diagnosis of its elevation in various clinical situations.

Transcriptomic Analysis Reveals an Altered Hcy Metabolism in the Stria Vascularis of the Pendred Syndrome Mouse Model

Purpose

Slc26a4^-/- mice exhibit severer defects in the development of the cochlea and develop deafness, while the underlying mechanisms responsible for these effects remain unclear. Our study was to investigate the potential mechanism linking SLC26A4 deficiency to hearing loss.

Materials and Methods

RNA sequencing was applied to analyze the differential gene expression of the stria vascularis (SV) from wildtype and Slc26a4^-/- mice. GO and KEGG pathway analysis were performed. Quantitative RT-PCR was applied to validate the expression of candidate genes affected by Slc26a4. ELISA and immunofluorescence technique were used to detect the homocysteine (Hcy) level in serum, brain, and SV, respectively.

Results

183 upregulated genes and 63 downregulated genes were identified in the SV associated with Slc26a4 depletion. Transcriptomic profiling revealed that Slc26a4 deficiency significantly affected the expression of genes associated with cell adhesion, transmembrane transport, and the biogenesis of multicellular organisms. The SV from Slc26a4^-/- mice exhibited a higher expression of Bhmt mRNAs, as well as altered homocysteine (Hcy) metabolism.

Conclusions

The altered expression of Bhmt results in a dramatic change in multiple biochemical reactions and a disruption of nutrient homeostasis in the endolymph which may contribute to hearing loss of Slc26a4 knockout mouse.

Updates in the advances of sporadic medullary thyroid carcinoma: from the molecules to the clinic

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine malignancy that originates in parafollicular cells. It is well-known that a quarter of MTC are involved in hereditary multiple endocrine neoplasia type 2 syndromes, whereas most MTC are sporadic. Unlike the commonly encountered gastrointestinal or pulmonary neuroendocrine tumors, most sporadic MTCs have distinct genetic alterations featured by somatic changes of either Rearranged during Transfection (RET) or RAS point mutation. The increasing application of next-generation sequencing, whole-exome sequencing, and other molecular detection techniques enables us to understand MTC comprehensively concerning its detailed molecular changes and their clinical correlations. This article reviews the advances in genetic alterations and their prognostic impact in sporadic MTC among different populations and discusses the associated tumor immune microenvironments and the potential role of immunotherapy targeting PD-L1/PD-1 in treating MTC. Furthermore, the current multikinase inhibitor targeting therapy for sporadic MTC has been summarized here and its efficacy and drug toxicity are discussed. Updates in advance of the role of calcitonin/procalcitonin/calcitonin-related polypeptide alpha (CALCA) gene transcripts in diagnosing and handling MTC are also mentioned. The treatment of advanced MTC is still challenging and might require a combination of several modalities.

Circulating RNA Transcriptome of Pregnant Women with TSH Just Above the Trimester-Specific Reference and its Correlation with the Hypertensive Phenotype

During gestation, a woman’s body undergoes physiological changes that alter thyroid function. Pregnant women with hypothyroidism may exhibit gestational complications, including hypertension and preeclampsia. We investigated differentially expressed genes (DEGs) in circulating RNAs from pregnant women with TSH levels just above the normal range to determine the impact of a mild elevation of TSH in pregnancy. We selected three women with healthy thyroid pregnancy (HTP), three pregnant women with gestational hypothyroidism (GHT), and three nonpregnant women (NPG) to construct transcriptome libraries. We also compared our results with data from the GEO dataset and DisGeNET. We identified 1500 DEG in GHT and 1656 DEG in HTP. From GEO dataset, we recognized 453 DEGs in trimester-specific plasma RNA, 1263 DEGs in placental tissues from healthy women, 1031 DEGs from preeclamptic uteroplacental tissues and 1657 DEGs from placental tissues from severely preeclamptic women. In this scenario, 12.26% and 12.86% genes were shared between these datasets in GHT and HTP, respectively. We stablished 62 genes in GHT DEGs related to hypertensive phenotype hallmarks. In conclusion, even in women with a mild TSH increment, we were able to detect some DEGs that could be associated with a hypertensive phenotype.

The uS8, uS4, eS31, and uL14 Ribosomal Protein Genes Are Dysregulated in Nasopharyngeal Carcinoma Cell Lines

The association of ribosomal proteins with carcinogenesis of nasopharyngeal carcinoma (NPC) has been established in a limited subset of ribosomal protein genes. To date, three ribosomal protein genes, eL27 (L27), eL41 (L41), and eL43 (L37a), have been found to be differentially expressed in cell lines derived from NPC tumors. This raises the possibility of more ribosomal protein genes that could be associated with NPC. In this study, we investigated the expression profiles of eight ribosomal protein genes, uS8 (S8), uS4 (S9), eS31 (S27a), eL6 (L6), eL18 (L18), uL14 (L23), eL24 (L24), and eL30 (L30), in six NPC-derived cell lines (HONE-1, SUNE1, HK1, TW01, TW04, and C666-1). Their expression levels were compared with that of a nonmalignant nasopharyngeal epithelial cell line (NP69) using quantitative real-time PCR (RT-qPCR) assay. Of the eight genes studied, the expressions of four ribosomal protein genes uS8 (S8), uS4 (S9), eS31 (S27a), and uL14 (L23) were found to be significantly downregulated in NPC cell lines relative to NP69. Our findings provide novel empirical evidence of these four ribosomal protein genes as NPC-associated genetic factors and reinforce the relevance of ribosomal proteins in the carcinogenesis of nasopharyngeal cancer.

A Concise Atlas of Thyroid Cancer Next-Generation Sequencing Panel ThyroSeq v.2

The next-generation sequencing technology allows high out-put genomic analysis. An innovative assay in thyroid cancer, ThyroSeq® was developed for targeted mutation detection by next generation sequencing technology in fine needle aspiration and tissue samples. ThyroSeq v.2 next generation sequencing panel offers simultaneous sequencing and detection in >1000 hotspots of 14 thyroid cancer-related genes and for 42 types of gene fusions known to occur in thyroid cancer. ThyroSeq is being increasingly used to further narrow the indeterminate category defined by cytology for thyroid nodules. From a surgical perspective, genomic profiling also provides prognostic and predictive information and closely relates to determination of surgical strategy. Both the genomic analysis technology and the informatics for the cancer genome data base are rapidly developing. In this paper, we have gathered existing information on the thyroid cancer-related genes involved in the initiation and progression of thyroid cancer. Our goal is to assemble a glossary for the current ThyroSeq genomic panel that can help elucidate the role genomics play in thyroid cancer oncogenesis.

A Genomic Alternative to Identify Medullary Thyroid Cancer Preoperatively in Thyroid Nodules with Indeterminate Cytology

BACKGROUND

The use of calcitonin screening for the rare medullary thyroid cancer (MTC) is controversial due to questions of efficacy, accuracy, and cost-effectiveness. This study reports the results of a large prospective validation using a machine-trained algorithm (MTC Classifier) to preoperatively identify MTC in fine-needle aspiration biopsies in lieu of calcitonin measurements.

METHODS

Cytology analysis on a prospective consecutive series of 50,430 thyroid nodule biopsies yielded a total of 7815 indeterminate (Bethesda categories III/IV) cases, which were tested with the MTC classifier. A prospective, consecutively submitted series of 2673 Bethesda III-VI cases with cytology determined locally was also evaluated. RNA was isolated and tested for the MTC Classifier using microarrays.

RESULTS

Forty-three cases were positive by the MTC Classifier among 10,488 tested nodules (0.4%), consistent with the low prevalence of MTC. Of these, all but one was histologically or biochemically confirmed as MTC, yielding a positive predictive value (PPV) of 98%. Of the positive cases, only 19 (44%) had been specifically suspected of MTC by cytology, highlighting the limitations of light microscopy to detect this disease. Three surgically confirmed MTC cases that were detected by the MTC Classifier had low basal serum calcitonin values, indicating these would have been missed by traditional calcitonin screening methods. A pooled analysis of three independent validation sets demonstrates high test sensitivity (97.9%), specificity (99.8%), PPV (97.9%), and negative predictive value (99.8%).

CONCLUSIONS

A clinical paradigm is proposed, whereby cytologically indeterminate thyroid nodules being tested for common malignancies using gene expression can be simultaneously tested for MTC using the same genomic assay at no added cost.

Epidemiology and Clinical Presentation of Medullary Thyroid Carcinoma

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor originating from the thyroid C cells producing mainly calcitonin (CTN) used as tumor marker. MTC occurs either sporadic (75%) or in a hereditary form (multiple endocrine neoplasia type 2, MEN2), due to germline mutations in the RET proto-oncogene. The discovery of an MTC in a patient has several diagnostic implications involving a specific strategy: preoperative evaluation of the tumor marker CTN and the extent of the disease, classification of MTC as sporadic or hereditary by DNA testing, and screening for associated endocrinopathies in hereditary MTC. Elevated CTN is a highly sensitive and specific tumor marker for diagnosis and follow-up of MTC. CTN is directly related to the tumor mass. In patients with nodular thyroid disease, diagnosis of MTC could be made by CTN determination as an indicator of tumor burden in conjunction with fine-needle aspiration. Patients with confirmed sporadic or hereditary MTC should have a total thyroidectomy and depending on the preoperative CTN value and the extent of disease additional dissection of the lymph nodes in the central and lateral neck compartment. In MEN 2 patients diagnosed by screening, the time of prophylactic thyroidectomy depends on RET mutation and CTN level.

Assessment of the Effect of Two Distinct Restricted Iodine Diet Durations on Urinary Iodine Levels (Collected over 24 h or as a Single-Spot Urinary Sample) and Na(+)/I(-) Symporter Expression

INTRODUCTION

A restricted iodine diet (RID) may be recommended for depletion of the whole-body iodine pool in patients with differentiated thyroid cancer referred for radioiodine treatment or a whole-body scan. Evaluation of the iodine pool is possible through urinary iodide (UI) measurements, which can be collected in 24-hour (24U) or spot urinary (sU) samples. However, the minimum period required for an RID to lower the iodine pool, the measurement of iodine in sU samples as a iodine pool marker, and the influence of the iodine pool on Na(+)/I(-) symporter (NIS) expression are debatable in the literature.

OBJECTIVES

To compare the effects of 15- and 30-day RID on UI measurements in 24U and sU samples and the impact of RID on NIS expression.

METHODS

Thyroidectomized patients went on a 15- or 30-day RID and collected 24U and sU samples before and after the RID. Twenty healthy individuals were evaluated for mRNA NIS expression before and after the RID.

RESULTS

Of 306 patients, only 125 properly complied with both the RID and 24U collection. We observed a correlation between sU and 24U UI before the RID (n = 306, ρ = 0.47, p < 0.001), after a 15-day RID (n = 79, ρ = 0.49, p < 0.001), and after a 30-day RID (n = 46, ρ = 0.73, p < 0.001). There was a significant decrease in UI after the RID. The median UI measurement was 275 μg/l at baseline and 99 and 80 μg/l after a 15- and 30-day RID, respectively. There was a significant increase in NIS expression after a 15-day RID.

CONCLUSIONS

A 15-day RID is sufficient to deplete the iodine pool. sU can replace 24U UI as a marker for assessing the iodine pool. NIS expression was increased after a 15-day RID.

Utility of serum procalcitonin for screening and risk stratification of medullary thyroid cancer

CONTEXT

The clinical utility of procalcitonin has not been demonstrated across the whole spectrum of medullary thyroid cancer (MTC).

OBJECTIVE

This serum biomarker validation study aimed at defining the diagnostic accuracy of procalcitonin for screening and risk stratification of MTC and delineating biochemical thresholds predictive of lymph node involvement in the neck and mediastinum.

DESIGN AND SETTING

This was a retrospective analysis at a tertiary referral center.

PATIENTS

Included in this study were 457 consecutive patients with previously untreated MTC, 112 of whom had procalcitonin and calcitonin serum levels determined before the initial operation.

INTERVENTION

The intervention was compartment-oriented surgery.

MAIN OUTCOME MEASURES

Main outcome measures included primary tumor diameter, extrathyroidal extension, lymph node metastases, distant metastases, and biochemical cure.

RESULTS

Receiver operating characteristics analyses revealed similar diagnostic accuracy for procalcitonin vs the current calcitonin standard, yielding comparable areas under the curve for primary tumors at thresholds of 10 (0.94 vs 0.93) and 40 (0.92 vs 0.84) mm; extrathyroidal extension (0.84 vs 0.83), lymph node metastasis (0.88 vs 0.86), and distant metastasis (0.93 vs 0.91). Lymph node metastases were present in the ipsilateral lateral neck with procalcitonin levels ≤1.0 ng/mL and the ipsilateral central neck with procalcitonin levels ≤0.25 ng/mL. Above a threshold of 1.0 ng/mL, lymph node metastases emerged in the contralateral central and lateral neck and above 5.0 ng/mL also in the upper mediastinum. When procalcitonin levels exceeded 1, 5, 10, and 50 ng/mL, biochemical cure rates declined to no more than 71%, 36%, 23%, and 10%, respectively.

CONCLUSION

Serum procalcitonin, having comparable diagnostic accuracy, has great potential to replace serum calcitonin as a new standard of care in the management of MTC because it does not need to be kept cool on ice or frozen and is easier to manage at the community level.

A ten-year clinical update of a large RET p.Gly533Cys kindred with medullary thyroid carcinoma emphasizes the need for an individualized assessment of affected relatives

OBJECTIVE

Reviewing the clinical outcomes of a large kindred with a RET p.Gly533Cys mutation, 10 years after the first description of this kindred, has provided an important set of clinical data for healthcare decision-making.

DESIGN AND PATIENTS

We identified 728 RET533 Brazilian relatives, spread out over 7 generations. We performed clinical examination, biochemical and imaging analyses in the proband and in 103 carriers.

MEASUREMENT AND RESULTS

The proband has been followed without evidence of structural disease in the last 10 years but with elevated calcitonin. The clinical and surgical features of 60 thyroidectomized RET533 relatives were also described. Forty-six patients had MTC (21-72 years), and 11 patients had C-cell hyperplasia (CCH) (5-42 years). Twelve MTC patients with lymph node metastases had a tumour size of 0·7-2·8 cm. Calcitonin level and CEA were correlated with disease stage, and none of the patients presented with an altered PTH or metanephrine. A 63-year-old woman developed pheochromocytoma and breast cancer. Two other RET533 relatives developed lung squamous cell carcinoma and melanoma.

CONCLUSIONS

A vast clinical variability in RET533 presentation was observed, ranging from only an elevated calcitonin level (3%) to local metastatic disease (25%). Many individuals were cured (42%) and the majority had controlled chronic disease (56%), reinforcing the need for individualized ongoing risk stratification assessment. The importance of this update relies on the fact that it allows us to delineate the natural history of RET 533 MEN2A 10 years after its first description.