Performance of current ultrasound-based malignancy risk stratification systems for thyroid nodules in patients with follicular neoplasms

Objectives To investigate the ability of the currently used ultrasound-based malignancy risk stratification systems for thyroid neoplasms (ATA, AACE/ACE/AME, K-TIRADS, EU-TIRADS, ACR-TIRADS and C-TIRADS) in distinguishing follicular thyroid carcinoma (FTC) from follicular thyroid adenoma (FTA). Additionally, we evaluated the ability of these systems in correctly determining the indication for biopsy. Methods Three hundred twenty-nine follicular neoplasms with definitive postoperative histopathology were included. The nodules were categorized according to each of six stratification systems, based on ultrasound findings. We dichotomized nodules into the positive predictive group of FTC (high and intermediate risk) and negative group of FTC based on the classification results. Missed biopsy was defined as neoplasms that were diagnosed as FTCs but for which biopsy was not indicated based on lesion classification. Unnecessary biopsy was defined as neoplasms that were diagnosed as FTAs but for whom biopsy was considered indicated based on classification. The diagnostic performance and missed and unnecessary biopsy rates were evaluated for each stratification system. Results The area under the curve of each system for distinguishing follicular neoplasms was < 0.700 (range, 0.511–0.611). The missed biopsy rates were 9.0–22.4%. The missed biopsy rates for lesions ≤ 4 cm and lesions sized 2–4 cm were 16.2–35.1% and 0–20.0%, respectively. Unnecessary biopsy rates were 65.3–93.1%. In ≤ 4 cm group, the unnecessary biopsy rates were 62.2–89.7%. Conclusion The malignancy risk stratification systems can select appropriate nodules for biopsy in follicular neoplasms, while they have limitations in distinguishing follicular neoplasms and reducing unnecessary biopsy. Specific stratification systems and recommendations should be established for follicular neoplasms. Key Points • Current ultrasound-based malignancy risk stratification systems of thyroid nodules had low efficiency in the characterization of follicular neoplasms. • The adopted stratification systems showed acceptable performance for selecting FTC for biopsy but unsatisfactory performance for reducing unnecessary biopsy.

The Utility of Serum Anti-thyroglobulin Antibody and Thyroglobulin in the Preoperative Differential Diagnosis of Thyroid Follicular Neoplasm

PurposeIt is challenging to distinguish follicular thyroid carcinoma (FTC) from follicular thyroid adenoma (FTA) before surgery due to the lack of malignant ultrasound features, the underdiagnosis by fine-needle biopsy, and the absence of definitive markers. We investigated whether thyroglobulin (Tg), anti-thyroglobulin antibody (TgAb), thyroid peroxidase antibodies (TPOAb), and thyroid stimulating hormone (TSH) could help differentiate FTC from FTA.MethodsA total of 319 patients with follicular neoplasms were included. We analyzed the serum markers as continuous and categorical variables between FTC and FTA. Also, we analyzed the prevalence of FTC in different serum markers groups.ResultsThe TgAb was a risk factor of FTC. Versus the TgAb group (≤11.68 IU/mL), OR of the group (11.69-30.50 IU/mL) and the group (＞30.50 IU/mL) were 2.206 (1.114-4.369, P=0.023) and 3.247 (1.684-6.260, P＜0.001), respectively. Versus the TgAb group (≤11.68 IU/mL), the malignant prevalence of the group (＞30.50 IU/mL) was higher (13.1% vs. 32.9%, P=0.001). In TgAb (-) patients, the Tg was another risk factor of FTC. Versus the Tg group (≤38.51 ng/mL), OR of the group (＞434.60 ng/mL) was 3.836 (1.625-9.058, P=0.002); the malignant prevalence of the group (＞434.60 ng/mL) was 47.2% and higher than other groups.ConclusionsThe TgAb and Tg may have utility in the preoperative differential diagnosis of follicular neoplasm. The higher TgAb and Tg were associated with higher malignant risk. Thus, we should be cautious of preoperative TgAb and Tg in follicular neoplasm.

Three-dimensional telomere profiles in papillary thyroid cancer variants: a pilot study

Papillary thyroid carcinoma (PTC) has two main histologic variants: classical-PTC (CL-PTC) and follicular variant PTC (FV-PTC). Recently, due to its similar features to benign lesions, the encapsulated FV-PTC variant was reclassified as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Nonetheless, specific molecular signatures are not yet available. It is well known that telomere-related genome instability is caused by inappropriate DNA repair of dysfunctional telomeres and that mechanisms involved in the damaged telomere repair processing may led to detrimental outcomes, altering the three-dimensional (3D) nuclear telomere and genome organization in cancer cells. This pilot study aimed to evaluate whether a specific 3D nuclear telomere architecture might characterize NIFTP, potentially distinguishing it from other PTC histologic variants. Our findings demonstrate that 3D telomere profiles of CL-PTC and FV-PTC were different from NIFTP and that NIFTP more closely resembles follicular thyroid adenoma (FTA). There was no association between BRAF expression and telomere length in all tested samples. Our data indicate that 3D telomere profiles of CL-PTC and FV-PTC were different from NIFTP and that NIFTP more closely resembles FTA. NIFTP has longer telomeres than CL-PTC and FV-PTC samples, and that telomere length of NIFTP overlaps with that of the FTA histotype. These preliminary findings reinforce the view that NIFTP are lesions closer to non-malignant thyroid nodules and confirmed that short telomeres are a feature of PTC.

Telomere-related Genomic Instability in Papillary Thyroid Cancers: A Preliminary Study

Papillary thyroid carcinoma (PTC) has two main histologic variants: classical-PTC (CL-PTC) and follicular variant PTC (FV-PTC). Recently, due to its similar features to benign lesions, the encapsulated FV-PTC variant was reclassified as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Nonetheless, specific molecular signatures are not yet available. It is well known that telomere-related genome instability is caused by inappropriate DNA repair of dysfunctional telomeres and that mechanisms involved in the damaged telomere repair processing may led to detrimental outcomes, altering the 3D nuclear telomere and genome organization in cancer cells. This pilot study aimed to evaluate whether a specific nuclear telomere architecture might characterize NIFTP, potentially distinguishing it from other PTC histologic variants. Our findings demonstrate that 3D telomere profiles of CL-PTC and FV-PTC were different from NIFTP and that NIFTP more closely resembles follicular thyroid adenoma (FTA). NIFTP has longer telomeres than CL-PTC and FV-PTC samples and telomere length overlaps in NIFTP and FTA. There was no association between BRAF expression and telomere length in all tested samples. Our data showing that 3D nuclear telomere organization is altered differently in thyroid cancer variants, suggest that this parameter might guide clinical management of NIFTP. Although further investigations in a larger cohort of patients are necessary to corroborate our observations, telomere-related genomic instability might be of value in the diagnosis of NIFTP and allow for a more appropriate selection of the correct treatment.

Comprehensive Assessment of TERT mRNA Expression across a Large Cohort of Benign and Malignant Thyroid Tumours

The presence of TERT promoter (TERTp) mutations in thyroid cancer have been associated with worse prognosis features, whereas the extent and meaning of the expression and activation of TERT in thyroid tumours is still largely unknown. We analysed frozen samples from a series of benign and malignant thyroid tumours, displaying non-aggressive features and low mutational burden in order to evaluate the presence of TERTp mutations and TERT mRNA expression in these settings. In this series, TERTp mutations were found in 2%, only in malignant cases, in larger cancers, and from older patients. TERT mRNA expression was detected in both benign and malignant tumours, with increased frequencies in the malignant tumours with aggressive histotypes, larger tumours, and from older patients. In benign tumours, TERT mRNA expression was found in 17% of the follicular thyroid adenoma (FTA) with increased levels of expression in smaller tumours and associated with the presence of thyroiditis. TERTp mutations and TERT mRNA expression are correlated with worse prognosis features in malignant thyroid tumours, whereas TERT mRNA expression in the benign tumours is associated with the presence of thyroiditis.

Network-Based Genetic Profiling Reveals Cellular Pathway Differences Between Follicular Thyroid Carcinoma and Follicular Thyroid Adenoma

Molecular mechanisms underlying the pathogenesis and progression of malignant thyroid cancers, such as follicular thyroid carcinomas (FTCs), and how these differ from benign thyroid lesions, are poorly understood. In this study, we employed network-based integrative analyses of FTC and benign follicular thyroid adenoma (FTA) lesion transcriptomes to identify key genes and pathways that differ between them. We first analysed a microarray gene expression dataset (Gene Expression Omnibus GSE82208, n = 52) obtained from FTC and FTA tissues to identify differentially expressed genes (DEGs). Pathway analyses of these DEGs were then performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) resources to identify potentially important pathways, and protein-protein interactions (PPIs) were examined to identify pathway hub genes. Our data analysis identified 598 DEGs, 133 genes with higher and 465 genes with lower expression in FTCs. We identified four significant pathways (one carbon pool by folate, p53 signalling, progesterone-mediated oocyte maturation signalling, and cell cycle pathways) connected to DEGs with high FTC expression; eight pathways were connected to DEGs with lower relative FTC expression. Ten GO groups were significantly connected with FTC-high expression DEGs and 80 with low-FTC expression DEGs. PPI analysis then identified 12 potential hub genes based on degree and betweenness centrality; namely, TOP2A, JUN, EGFR, CDK1, FOS, CDKN3, EZH2, TYMS, PBK, CDH1, UBE2C, and CCNB2. Moreover, transcription factors (TFs) were identified that may underlie gene expression differences observed between FTC and FTA, including FOXC1, GATA2, YY1, FOXL1, E2F1, NFIC, SRF, TFAP2A, HINFP, and CREB1. We also identified microRNA (miRNAs) that may also affect transcript levels of DEGs; these included hsa-mir-335-5p, -26b-5p, -124-3p, -16-5p, -192-5p, -1-3p, -17-5p, -92a-3p, -215-5p, and -20a-5p. Thus, our study identified DEGs, molecular pathways, TFs, and miRNAs that reflect molecular mechanisms that differ between FTC and benign FTA. Given the general similarities of these lesions and common tissue origin, some of these differences may reflect malignant progression potential, and include useful candidate biomarkers for FTC and identifying factors important for FTC pathogenesis.

Differences in Mutational Profile between Follicular Thyroid Carcinoma and Follicular Thyroid Adenoma Identified Using Next Generation Sequencing

We aimed to identify differences in mutational status between follicular thyroid adenoma (FTA) and follicular thyroid cancer (FTC). The study included 35 patients with FTA and 35 with FTC. DNA was extracted from formalin-fixed paraffin-embedded (FFPE) samples from thyroidectomy. Next-generation sequencing (NGS) was performed with the 50-gene Ion AmpliSeq Cancer Hotspot Panel v2. Potentially pathogenic mutations were found in 14 (40%) FTA and 24 (69%) FTC patients (OR (95%CI) = 3.27 (1.22−8.75)). The number of mutations was higher in patients with FTC than FTA (p-value = 0.03). SMAD4 and STK11 mutations were present only in patients with FTA, while defects in FBXW7, JAK3, KIT, NRAS, PIK3CA, SMARCB1, and TP53 were detected exclusively in FTC patients. TP53 mutations increased the risk of FTC; OR (95%CI) = 29.24 (1.64–522.00); p-value = 0.001. FLT3-positivity was higher in FTC than in the FTA group (51.4% vs. 28.6%; p-value = 0.051). The presence of FLT3 and TP53 with no RET mutations increased FTC detectability by 17.1%, whereas the absence of FLT3 and TP53 with a presence of RET mutations increased FTA detectability by 5.7%. TP53 and FLT3 are candidate markers for detecting malignancy in follicular lesions. The best model to predict FTA and FTC may consist of FLT3, TP53, and RET mutations considered together.