Clinicopathologic and molecular characterization of NTRK-rearranged thyroid carcinoma (NRTC)

Molecular oncology of iodine refractory thyroid cancer current therapies and perspective

Thyroid cancer (TC) is the most common endocrine malignancy. Most patients will be treated and cured by surgery but a low percentage will develop advanced disease. The treatment of advanced disease is at first the use of radioiodine treatment in differentiated cancer then at progression will rely on molecular alterations and consequently in targeted treatments. In this review, we will explore the most frequent molecular alterations of each histological subtype: differentiated thyroid cancer (DTC), anaplastic thyroid cancer (ATC), medullary thyroid cancers (MTC) and clinically tested and approved treatment. We will also report the clinical and preclinical perspective in this field.

Systematic literature review of the epidemiology of neurotrophic tyrosine receptor kinase positive solid tumor sites

AIMS

This study aimed to expand on existing systematic literature reviews (SLRs) by assessing the prevalence of neurotrophic tyrosine receptor kinase (NTRK) fusion-positive mutations across solid tumors in adult U.S populations. It further evaluated incidence, testing, treatment, mortality, and progression rates by tumor type, extending evidence through 2023.

MATERIALS & METHODS

A SLR was conducted following Cochrane and PRISMA guidelines, with searches across Ovid Embase, Ovid MEDLINE, and Cochrane Library databases for studies published from 2013 to August 2023. Eligibility criteria included studies on NTRK fusion-positive tumors in patients aged ≥12 years. Data were extracted and assessed using the Newcastle-Ottawa Scale and JBI checklist.

RESULTS

This SLR identified 160 studies, reporting NTRK fusion prevalence ranging from 0.03% to 0.70% across solid tumors. TRK inhibitors, particularly larotrectinib and entrectinib, were commonly used treatments. Prevalence varied significantly by cancer type, being higher in rarer cancers, such as papillary thyroid carcinoma (up to 21.4%).

CONCLUSIONS

NTRK fusions are rare, with wide prevalence variability among cancer types. The findings highlight the need for standardized diagnostic methods and larger real-world studies to improve prevalence estimates and assess the impact of NTRK fusions on outcomes, ultimately aiding in the optimization of targeted treatments for affected patients.

The value of preoperative molecular testing in the management of Bethesda V and Bethesda VI thyroid tumors

The incidence of thyroid cancer has increased over recent years due to the fact that several diagnostic tools, such as neck ultrasound and fine-needle aspiration, are being ever more widely adopted. Lately, another modality which might provide significant information preoperatively on the aggressiveness of a thyroid tumor, its prognosis, and its recurrence rate is molecular testing. We reviewed the literature with regard to the role of preoperative molecular testing in patients with Bethesda V and Bethesda VI thyroid nodules and its impact on choice of the optimal treatment strategy. Several molecular mutations and alterations are associated with thyroid cancer and its biological behavior, such as BRAF-V600E, RET, and TERT promoter. Although the value of preoperative molecular testing for indeterminate nodules (Bethesda III and Bethesda IV) have been analyzed in numerous studies, the impact of preoperative molecular testing on Bethesda V and Bethesda VI thyroid nodules is not adequately described in the current literature. The preoperative recognition of specific molecular mutations, such as BRAFV600E and TERT promoter mutation, might provide more individualized management for thyroid cancer patients by altering the surgical approach and the extent of surgery for patients diagnosed with a more aggressive or iodine-resistant subtype of thyroid cancer.Thyroid cancer is characterized by multiple genetic mutations and alterations and, as a result, preoperative molecular testing of malignant nodules could be a very useful tool for surgeons, enabling them to decide on the most appropriate surgical approach for each patient.

NTRK Fusion-Positive Thyroid Carcinoma: From Diagnosis to Targeted Therapy

PURPOSE

Neurotrophic tropomyosin receptor kinase (NTRK) fusions may act as an oncogenic driver in thyroid carcinomas. Given their low frequency, clinical, pathological, and molecular data on these patients and their responses to targeted therapies are limited.

METHODS

This is an observational retrospective study conducted at a single high-volume cancer center in the United States. Data were retrospectively collected from medical records.

RESULTS

We included 65 patients (37 adult, 28 pediatric) with an NTRK fusion-positive thyroid carcinoma (24 NTRK1, 41 NTRK3), of which 54 were papillary thyroid carcinomas (PTC), four poorly differentiated thyroid carcinomas (PDTC), and seven anaplastic thyroid carcinomas (ATC). In PTC, an extensive follicular growth pattern was seen in 22 (41%) patients. In adults, NTRK3 fusions were 3 times more frequent (nine NTRK1, 28 NTRK3), whereas in pediatric patients their frequencies were similar (15 NTRK1, 13 NTRK3; P = .021). In patients with PDTC/ATC treated with larotrectinib, we detected four emergent solvent front mutations (three NTRK3 G623R, one NTRK1 G595R) causing resistance to drug and disease progression. Three of them (two ATC, one PDTC) received second-line selitrectinib on a clinical trial. Partial responses were seen in all three patients, but both patients with ATC progressed within a year.

CONCLUSION

NTRK1/3 fusions are seen in PTC, PDTC, and ATC, and a follicular growth pattern was observed in a high proportion of cases. In patients treated with larotrectinib, NTRK solvent front mutations are the main resistance mechanism, frequently occurring in PDTC/ATC. Responses to single-agent TRK inhibitor are short-lived in patients with ATC; thus, these drugs should be used with caution in this population.

Hidden in Plain Sight: Incidental Diagnosis of Metastatic Papillary Thyroid Microcarcinoma Without Radiologically Apparent Thyroid Tumor

Background/Objective

Papillary thyroid cancer (PTC) is considered the most common form of thyroid cancer. Papillary thyroid microcarcinomas (PTMCs) are defined as papillary carcinomas that are <1 cm and are often identified on surgical pathology but may be missed by ultrasound imaging.

Case Report

Our case describes a 24-year-old woman who initially presented with a right lateral neck lump. This was thought to be a lipoma, and no workup was performed until it began to grow during pregnancy 3 to 4 years after initial presentation. The patient underwent excision with findings of a level 5B lymph node with pathology consistent with PTC, follicular variant. Neck ultrasound performed in an imaging center and in our clinic did not reveal thyroid nodules or abnormal appearing lymph nodes. Solid tumor profiling assay identified a neurotrophic tropomyosin receptor kinase (NTRK)-3 fusion: ETV6(4)-NTRK3(14) mutation.

Discussion

PTMCs are identified with increased frequency due to improved ultrasound imaging and fine needle aspiration techniques. PTMCs are often associated with a benign course and are rarely metastatic. There has been growing interest in NTRK fusion mutations in PTC that has been associated with an increased risk of metastasis.

Conclusion

This case is unusual in that multiple cervical nodal metastases were present even without a sizable primary thyroid tumor. Although more studies are needed to elucidate the clinical and prognostic significance of NTRK fusion mutations in PTMC, their response to tropomyosin receptor kinase inhibitors may represent a future pathway for treatment.

NTRK fusion promotes tumor migration and invasion through epithelial-mesenchymal transition and closely interacts with ECM1 and NOVA1

BACKGROUND

The NTRK fusion gene is a rare cancer driver and a typical representative "diamond mutation". Its unique role in tumor progression is highly important for the clinical diagnosis and treatment of patients with tumors. We searched for NTRK fusion-positive patients in our hospital. As of August 2022, a total of 8 patients were affected. We discovered that NTRK fusion was associated with enhanced tumor invasion and migration ability. Previous reports also support this finding, but its underlying mechanism has not been elucidated.

METHODS

We undertook a comprehensive exploration of the correlations between NTRK fusions and tumor invasion as well as migration by analysing clinical data, performing bioinformatics analysis via public databases, and conducting in vitro cell experiments.

RESULTS

We ascertained that within the thyroid cancer (THCA) dataset and the pancancer dataset, ECM1 and NOVA1 were coexpressed with NTRKs. Additionally, they demonstrated a significant association with the activity of the epithelial‒mesenchymal transition (EMT) pathway. Furthermore, these genes are overexpressed in various cancers and are associated with advanced clinical stage and increased aggressiveness. Our in vitro study revealed that larolutinib potentially inhibited the invasion and metastasis ability of NTRK-fused cells. Interestingly, contrary to previous findings, the repression of ECM1 increased the migration and invasion ability of NTRK-fused tumor cells.

CONCLUSIONS

NTRK fusion tumors present heightened migratory and invasive potential in clinical settings. Further experiments confirmed the significant inhibitory effects of TRK inhibitors on the migration and invasion abilities of these cells. There is a complex relationship between ECM1, NOVA1 and NTRK fusion; however, further research is needed to determine whether NTRK fusion promotes tumor metastasis through these two genes.

Effective Preparation of FFPE Tissue Samples for Preserving Appropriate Nucleic Acid Quality for Genomic Analysis in Thyroid Carcinoma

Formalin-fixed paraffin-embedded (FFPE) tissue samples are important for genomic analysis of thyroid carcinomas, particularly for various molecularly targeted therapies. Therefore, this study developed and validated a technique for preparing FFPE tissue samples that preserves nucleic acid quality, which is fundamental for precise genomic analysis, more effectively than conventional methods. We analyzed surgically resected thyroid gland tumors, lymph node metastases, and separately fixed tumor samples to optimize formalin fixation and assess the influence of specimen type and preparation methods on nucleic acid quality. We assessed several quality indicators, including the DNA integrity number, cycle threshold ratio, RNA integrity number, and DV200. Separately fixed tumor samples consistently exhibited higher DNA and RNA quality than conventionally processed samples. Additionally, lymph node metastases often exhibit nucleic acid quality matching or exceeding that of thyroid gland tumors, highlighting their potential reliability for genomic analysis. These findings suggest the utility of various specimen types for the comprehensive genetic profiling of thyroid carcinomas. In conclusion, this study demonstrated that preparing separately fixed tumor samples is an effective method for preserving DNA and RNA quality for genomic analyses. Biopsy punches enable specimen collection at various facilities, including those without the ability to handle frozen specimens. This contributes to the development of a method for obtaining high-quality pathological samples that can be widely used in general medical practice. Moreover, lymph node metastases often exhibit nucleic acid quality equal to or superior to that of thyroid gland tumors, highlighting their potential as acceptable sources for genomic analyses.

NTRK Gene Expression Analysis in Oral Squamous Cell Carcinoma Mexican Population

Oral cancer holds the sixth position in malignancies worldwide; 90% correspond to oral squamous cell carcinoma (OSCC). Diverse reports suggest that NTRK genes and their receptors are key oncogenesis regulators to tumor progression in human cancers. Objective: To analyze the NTRK and Trk expression and their association with clinicopathological features of OSCC in Mexican patients' samples. Material and Methods: We analyzed 95 OSCC cases of pan-trk immunoexpression through a software-assisted method. Gene expression was analyzed by RT-qPCR employing the ΔΔCT method. Kruskal-Wallis and Spearman's correlation tests were performed. Results: Our mean age was 62.4 (±16.9) years. A total of 37 cases were tumors in the lateral border of the tongue. Age was significantly associated with the anatomical site. 42% (40 of 95) cases were pan-trk positive. A total of 21 cases showed intense immunoexpression predominantly in poorly differentiated OSCC, with a significant correlation between immunoexpression and age and gender. Gene expression showed that poorly differentiated cases exhibited higher NTRK2 expression, while well-differentiated cases demonstrated NTRK3 significantly higher expression. Conclusions: Our results suggest that NTRK family expression is present in OSCC, with differential expression related to differentiation degree. Additional information about their activation or mutational status could reinforce their potential as a possible primary or adjuvant treatment target.

Secretory Carcinoma of the Thyroid: A Case Report and Update of Literature

Primary secretory carcinoma (SC) of the thyroid gland is a rare neoplasm, characterized by the presence of oncogenic ETV6::NTRK3 fusions, which are amenable to tropomyosin receptor kinase (TRK) inhibitor therapy. Despite its morphologic, immunophenotypic, and genetic similarities to SC of the salivary and mammary glands, diagnostic pitfalls may arise in differentiating from papillary thyroid carcinoma due to overlapping features such as papillary growth, nuclear irregularity, and variable expression of PAX8. Tumor misclassification may lead to delayed consideration of molecular testing and targeted therapy. A total of 13 cases of thyroid SC have been documented in the literature, indicating a tendency for advanced clinical presentation followed by a protracted clinical course, with most patients surviving until the end of the study period despite some experiencing recurrences. However, tumor-related mortality occurred in around 30% of cases, with the overall survival ranging from days to years, underscoring the variability in tumor behavior and the need for further research efforts. Among documented cases of thyroid SC, prognostic factors established for salivary SC have shown broad distributions, including a mitotic activity ranging from < 1 to 10 per 10 high-power fields and variable presence of necrosis, awaiting additional case experience to better elucidate their relevance in thyroid SC. We hereby present a 61-year-old female patient with widely metastatic thyroid SC treated with larotrectinib and provide an updated review of the literature on the molecular pathogenesis and clinicopathologic characteristics of this rare entity.

Larotrectinib efficacy for liver metastases in papillary thyroid carcinoma patient harboring SQSTM1-NTRK1 fusion

BACKGROUND

Pooled data analysis from three phase I/II larotrectinib clinical trials revealed that larotrectinib demonstrated rapid and durable disease control and a favorable safety profile for patients with neurotrophic-tropomyosin receptor kinase (NTRK) fusion positive thyroid carcinoma. Herein, we report the case of a patient with papillary thyroid carcinoma (PTC) and liver metastases who demonstrated a durable response to treatment with larotrectinib.

CASE PRESENTATION

A 50-year-old female with PTC was referred to our hospital for postoperative observation. Computed tomography (CT) scan was performed to screen for distant metastasis, since thyroglobulin concentration increased gradually, and revealed multiple distant metastases, including multiple liver metastases. Radioactive iodine was administered at a dose of 100 mCi. However, uptake was observed only in the thyroid bed, and distant metastases had no avidity. As liver metastases progressed, lenvatinib (24 mg/day) was initiated after confirmation of liver metastases by liver biopsy 9 years and 1 month after the initial referral to our hospital. Since the multiple metastases became refractory for lenvatinib, the OncoGuide™ NCC Oncopanel System was performed, and the SQSTM1-NTRK1 gene fusion was confirmed. Larotrectinib was subsequently administered at a dose of 200 mg/day. The CT before the initiation of larotrectinib showed multiple liver metastases with a maximum diameter of 48 mm. The first CT evaluation at 1 month after the initiation of larotrectinib treatment showed that the tumor volume was reduced by 28% in the RECIST 1.1 criteria. After 3 months of larotrectinib treatment, a 38% reduction in the tumor volume was achieved as the best clinical response. The only side effect was grade 1 myalgia. At 12 months after the initiation of larotrectinib treatment, none of the lesions had progressed.

CONCLUSIONS

In conclusion, larotrectinib demonstrated effective antitumor activity against liver metastases of PTC, a relatively rare site of distant metastasis. Furthermore, the efficacy of larotrectinib was maintained, even though the patient had a history of multi-tyrosine kinase inhibitor treatment and a relatively infrequent fusion gene, SQSTM1-NTRK1.

A comparison of the histopathologic features of thyroid carcinomas with NTRK fusions to those with other malignant fusions

BACKGROUND

Chromosomal rearrangements involving one of the NTRK genes result in oncogenic driver mutations in thyroid carcinoma (TC) and serve as a target for therapy. We compared the clinicopathologic features of thyroid carcinomas with NTRK fusions vs. thyroid neoplasms with other malignancy associated gene fusions within our institution.

MATERIALS AND METHODS

Our pathology archives were searched from 2013 to 2023 for thyroid neoplasms with gene fusions, excluding THADA fusions and medullary thyroid carcinomas.

RESULTS

55 thyroid lesions were identified: 22 with NTRK fusions (NTRK cohort) and 33 with other fusions (non-NTRK cohort). On fine needle aspiration (FNA), 54% of the NTRK cohort were classified as Category V as per Bethesda System for Reporting Thyroid Cytology (TBSRTC) and 51.5% of non-NTRK cohort as TBSRTC Category III. In the NTRK cohort, the most common reported fusion was ETV6::NTRK3 and the most common reported fusion in the non-NTRK cohort was PAX8::PPAR-gamma. On histologic examination both cohorts were most commonly diagnosed as PTC follicular variant. Invasive features were more common in the NTRK cohort in comparison to the non-NTRK cohort. Locoregional recurrence occurred in 2/22 NTRK cases and 2/33 non-NTRK cases, with average time from surgery to recurrence being 5.5 months and 21 months, respectively. The majority of patients in both groups are alive with no evidence of disease.

CONCLUSIONS

Thyroid neoplasms with a malignancy associated gene fusion are likely to be diagnosed as subtype/variant of PTC. Patients whose thyroid lesions harbor NTRK fusions present with a PTC-FV that on presentation has more aggressive clinicopathologic findings and are likely to have earlier disease recurrence.

Uncommon molecular alterations in follicular-derived thyroid carcinoma: A single institution study

Thyroid carcinomas are the most common endocrine malignancy and commonly have alterations in the mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3 kinase (PI3K)/AKT signaling pathways in well-differentiated tumors. Alternative molecular alterations driving thyroid carcinomas have been identified rarely in the literature and are more likely to occur in poorly differentiated or anaplastic cases. In this study, uncommon genetic alterations such as MLH1, MSH2, NSD3::NUTM1, RET::SPECC1L, and G3BP2::FGFR2 were identified in patients with papillary thyroid carcinoma, poorly differentiated thyroid carcinoma, and differentiated high-grade thyroid carcinoma. Most of these tumors demonstrated an aggressive biological behavior. Atypical driver mutations in thyroid carcinomas can occur in patients with cancer predisposition syndromes as demonstrated by an NTRK1::TPM3 fusion in a patient with Li Fraumeni syndrome. In these settings of more aggressive disease, molecular testing targeting actionable fusions and mutations is important. As demonstrated in our case cohort, 100% of cases diagnosed as high-grade follicular-derived thyroid carcinoma had a mutation or fusion that is associated with worse prognosis, has a germline syndrome association requiring further work up, or an actionable mutation. This high yield seen in this cohort for molecular testing in patients with high-grade follicular-derived thyroid carcinoma suggests more routine molecular testing in this population would be a beneficial clinical practice.

Molecular Pathology of Thyroid Tumors: Old Problems and New Concepts

The molecular signatures of many thyroid tumors have been uncovered. These discoveries have translated into clinical practice and are changing diagnostic and tumor classification paradigms. Here, the findings of recent studies are presented with special emphasis on how molecular insights are impacting the understating of RAS mutant thyroid nodules, Hürthel cell neoplasms, and unusual thyroid tumors, such as hyalinizing trabecular tumor, secretory carcinoma of the thyroid, and sclerosing mucoepidermoid carcinoma with eosinophilia. In addition, the utility of detecting actionable molecular alterations by immunohistochemistry in advanced and aggressive thyroid cancer is also discussed.

Clinicopathological features of two cases of ETV6-NTRK3 rearranged papillary thyroid carcinoma: a case report

Rearrangements involving the neurotrophic-tropomyosin receptor kinase (NTRK) gene family (NTRK1, NTRK2, and NTRK3) have been identified as drivers in a wide variety of human cancers. However, the association between NTRK rearranged thyroid carcinoma and clinicopathological characteristics has not yet been established. In our study, we retrospectively reviewed medical records of thyroid cancer patients and identified 2 cases with NTRK rearrangement, no additional molecular alterations were observed in either of these cases. The fusion of the rearrangement in both cases was ETV6(E4)::NTRK3(E14). By analyzing the clinicopathological features of these two cases, we found that both were characterized by multiple tumor nodules, invasive growth, and central lymph node metastases, indicating the follicular subtype of papillary thyroid carcinoma. Immunohistochemical staining profiles showed CD56-, CK19+, Galectin-3+, HBME1+. These clinicopathological features suggest the possibility of ETV6-NTRK3 rearranged thyroid carcinoma and highlight the importance of performing gene fusion testing by FISH or NGS for these patients.

Efficient Identification of Patients With NTRK Fusions Using a Supervised Tumor-Agnostic Approach

CONTEXT.—

The neurotrophic tropomyosin receptor kinase (NTRK) family gene rearrangements have been recently incorporated as predictive biomarkers in a "tumor-agnostic" manner. However, the identification of these patients is extremely challenging because the overall frequency of NTRK fusions is below 1%. Academic groups and professional organizations have released recommendations on the algorithms to detect NTRK fusions. The European Society for Medical Oncology proposal encourages the use of next-generation sequencing (NGS) if available, or alternatively immunohistochemistry (IHC) could be used for screening with NGS confirmation of all positive IHC results. Other academic groups have included histologic and genomic information in the testing algorithm.

OBJECTIVE.—

To apply some of these triaging strategies for a more efficient identification of NTRK fusions within a single institution, so pathologists can gain practical insight on how to start looking for NTRK fusions.

DESIGN.—

A multiparametric strategy combining histologic (secretory carcinomas of the breast and salivary gland; papillary thyroid carcinomas; infantile fibrosarcoma) and genomic (driver-negative non-small cell lung carcinomas, microsatellite instability-high colorectal adenocarcinomas, and wild-type gastrointestinal stromal tumors) triaging was put forward.

RESULTS.—

Samples from 323 tumors were stained with the VENTANA pan-TRK EPR17341 Assay as a screening method. All positive IHC cases were simultaneously studied by 2 NGS tests, Oncomine Comprehensive Assay v3 and FoundationOne CDx. With this approach, the detection rate of NTRK fusions was 20 times higher (5.57%) by only screening 323 patients than the largest cohort in the literature (0.30%) comprising several hundred thousand patients.

CONCLUSIONS.—

Based on our findings, we propose a multiparametric strategy (ie, "supervised tumor-agnostic approach") when pathologists start searching for NTRK fusions.

Neurotrophic-tyrosine receptor kinase gene fusion in papillary thyroid cancer: A clinicogenomic biobank and record linkage study from Finland

Selective tropomyosin receptor kinase (TRK) inhibitors are approved targeted therapies for patients with solid tumors harboring a neurotrophic tyrosine receptor kinase (NTRK) gene fusion. Country-specific estimates of NTRK gene fusion frequency, and knowledge on the characteristics of affected patients, are limited. We identified patients with histologically-confirmed papillary thyroid cancer (PTC) from Finland's Auria Biobank. TRK protein expression was determined by pan-TRK immunohistochemistry. Immuno-stained tumor samples were scored by a certified pathologist. Gene fusions and other co-occurring gene alterations were identified by next generation sequencing. Patient characteristics and vital status were determined from linked hospital electronic health records (EHRs). Patients were followed from 1 year before PTC diagnosis until death. 6/389 (1.5%) PTC patients had an NTRK gene fusion (all NTRK3); mean age 43.8 years (and none had comorbidities) at PTC diagnosis. Gene fusion partners were EML4 (n = 3), ETV6 (n = 2), and RBPMS (n = 1). Of 3/6 patients with complete EHRs, all received radioactive iodine ablation only and were alive at end of follow-up (median observation, 9.12 years). In conclusion, NTRK gene fusion is infrequent in patients with PTC. Linkage of biobank samples to EHRs is feasible in describing the characteristics and outcomes of patients with PTC and potentially other cancer types.

Management of radioiodine refractory differentiated thyroid cancer: the Latin American perspective

Radioiodine (RAI) refractory differentiated thyroid cancer is an uncommon and challenging situation that requires a multidisciplinary approach to therapeutic strategies. The definition of RAI-refractoriness is usually a clear situation in specialized centers. However, the right moment for initiation of multikinase inhibitors (MKI), the time and availability for genomic testing, and the possibility of prescribing MKI and selective kinase inhibitors differ worldwide.Latin America (LA) refers to the territories of the world that stretch across two regions: North America (including Central America and the Caribbean) and South America, containing 8.5% of the world's population. In this manuscript, we critically review the current standard approach recommended for patients with RAI refractory differentiated thyroid cancer, emphasizing the challenges faced in LA. To achieve this objective, the Latin American Thyroid Society (LATS) convened a panel of experts from Brazil, Argentina, Chile, and Colombia. Access to MKI compounds continues to be a challenge in all LA countries. This is true not only for MKI but also for the new selective tyrosine kinase inhibitor, which will also require genomic testing, that is not widely available. Thus, as precision medicine advances, significant disparities will be made more evident, and despite efforts to improve coverage and reimbursement, molecular-based precision medicine remains inaccessible to most of the LA population. Efforts should be undertaken to alleviate the discrepancies between the current state-of-the-art care for RAI-refractory differentiated thyroid cancer and the present situation in Latin America.

Secretory breast carcinoma: clinicopathological features and prognosis of 52 patients

PURPOSE

Secretory breast carcinoma is a rare histological subtype of invasive breast cancer and considered with an indolent clinical behavior. This study was conducted to analyze the clinicopathological features of patients with secretory breast carcinoma (SBC), explore the outcome, and compare the prognostic difference with invasive ductal breast carcinoma (IDC). METHODS AND MATERIALS: Patients with SBC diagnosed between 2006 and 2017 from Fudan University Shanghai Cancer Center were included in the study, excluding patients with previous malignant tumor history and incomplete clinical data or follow-up records. Peculiar clinicopathological and immunohistochemical features of the cases were fully described. Clinical data of 4979 cases of IDC were also evaluated during this period. After propensity score matching, prognostic analysis of SBCs and IDCs was calculated by Kaplan-Meier method and landmark analysis method.

RESULTS

The data of 52 patients diagnosed with SBC were identified from the pathological files. Among them, 47 patients were women, and 5 were men. The median age of the 52 SBCs was 46 years (mean, 48.1 years; range, 10-80 years). The tumor sizes ranged from 0.3 to 6.8 cm, with a mean of 3.5 cm. Eight patients (15.4%) had positive axillary lymph node involvement. The molecular classification was mostly triple-negative breast cancer (65.4%). Fluorescence in situ hybridization confirmed the presence of ETV6::NTRK3 rearrangement in 16 of 18 cases (88.9%). Furthermore, Kaplan-Meier survival analysis and landmark analysis demonstrated that there were no statistically significant differences in DFS and OS between SBC and IDC patients.

CONCLUSION

Although SBCs are generally associated with a favorable prognosis, our work exhibited that the clinicopathological features of SBC were partly different from former understandings, indicating that therapeutic procedure should be prudent. Further studies are necessary to fully identify the clinical behavior and predictive markers to improve diagnosis and management in this unique subtype of breast cancer.

Macrofollicular Architecture in Invasive Encapsulated Follicular Variant of Papillary Thyroid Carcinoma: A Pitfall in Thyroid Practice

BACKGROUND

Predominantly macrofollicular architecture in invasive encapsulated follicular variant of papillary thyroid carcinoma (IEFVPTC-MF) is rare and often a cause of misinterpretation during pre-operative work-up and histopathology evaluation. We comprehensively evaluated the radiological, cytological, gross, microscopic, molecular and follow-up characteristics of four such cases, intending to increase its recognition and add our experience to the limited literature available.

METHODS

All such histopathologically-proven cases of IEFVPTC-MF were retrieved from the departmental archives. The clinical details, thyroid ultrasound, cytology and thyroid scan findings were reviewed. Allele-specific PCR for BRAF p.V600E, KRAS, NRAS, and HRAS mutations, and FISH assays for ETV6::NTRK3 fusion and RET fusions were performed.

RESULTS

There were four cases of IEFVPTC-MF diagnosed between 2021 and 2022, involving two males and two females. The median age at presentation was 27 years, and the duration of the disease was 1-10 years. Thyroid ultrasound was TR1 (benign; n = 1), TR2 (not suspicious; n = 2), or TR4 (moderately suspicious; n = 1). Cytology was categorized as nondiagnostic (n = 1), benign (n = 1), and atypia of undetermined significance (n = 1). The three nodules with available cytology smears showed abundant colloid. Cells were arranged as sheets/microfollicles/clusters. Nuclei were predominantly round with minimal/focal elongation, membrane irregularity, and cellular crowding. On gross examination, cut surfaces of the tumors showed variable amounts of colloid. The tumors were solid-cystic. Histopathology revealed partially encapsulated multinodular tumors. There were prominent pseudopapillae projecting into the lumina of macrofollicles. Nuclei were predominantly round with variable nuclear atypia, including chromatin clearing and multifocal presence of nuclear grooves. Pseudoinclusions were identified in two. Molecular analysis revealed NRAS codon 61 mutation and ETV6::NTRK3 fusion in one case each. Two patients had cervical lymph node and hematogenous metastases. Post-radio-active iodine, the response was structurally incomplete (n = 2), indeterminate (n = 1) and excellent (n = 1).

CONCLUSIONS

Macrofollicular architecture in invasive encapsulated follicular variant of papillary thyroid carcinoma is a major pitfall in thyroid oncology practice. Long-standing disease, and ultrasonographic and cytological features that overlap with benign disease, often lead to underdiagnosis during pre-operative evaluation. As patients may consequently develop distant metastases and have inadequate treatment response, there is a need for more vigilant understanding of the spectrum of macrofollicular thyroid disease for accurate diagnosis. ETV6::NTRK3 or other fusions, when found, present opportunities for targeted therapy.

NTRK fusion events and targeted treatment of advanced radioiodine refractory thyroid cancer

PURPOSE

Pathogenic fusion events involving neurotrophic receptor tyrosine kinase (NTRK) have been described in ~ 2% of differentiated thyroid cancer (DTC). The selective tropomyosin receptor kinase (TRK) inhibitors entrectinib and larotrectinib have been approved in a tumor agnostic manner based on phase 1/2 clinical trials. In a real-world setting at five referral centers, we aimed to describe the prevalence of NTRK gene fusions and the efficacy and safety of TRK inhibitor treatment for non-medullary, advanced thyroid cancer (TC).

METHODS

A total of 184 TC patients with testing for NTRK gene fusions were included. Progression-free survival (PFS) and overall survival (OS) probabilities were estimated using the Kaplan-Meier method in six patients with NTRK fusion-positive TC who underwent TRK inhibitor therapy.

RESULTS

8/184 (4%) patients harbored NTRK gene fusions. Six patients with radioiodine (RAI)-refractory TC harboring NTRK1 (n = 4) and NTRK3 (n = 2) gene fusions were treated with larotrectinib. Five patients (83%) had received ≥ 1 prior systemic therapy and one patient did not receive prior systemic therapy. All patients had morphologically progressive disease before treatment initiation. Objective response rate was 83%, including two complete remissions. Median PFS from start of TRK inhibitor treatment was 23 months (95% confidence interval [CI], 0-57.4) and median OS was not reached (NR) (95% CI, NR). Adverse events were of grade 1-3.

CONCLUSION

The prevalence of NTRK gene fusions in our cohort of RAI-refractory TC is slightly higher than reported for all TC patients. Larotrectinib is an effective treatment option in the majority of NTRK gene fusion-positive advanced TC patients after prior systemic treatment and has a favorable safety profile.

A Shift in Molecular Drivers of Papillary Thyroid Carcinoma Following the 2017 World Health Organization Classification: Characterization of 554 Consecutive Tumors With Emphasis on BRAF-Negative Cases

Most studies for comprehensive molecular profiling of papillary thyroid carcinoma (PTC) have been performed before the 2017 World Health Organization (WHO) classification, in which the diagnostic criteria of follicular variants of PTC have been modified and noninvasive follicular thyroid neoplasm with papillary-like nuclear features has been introduced. This study aims to investigate the shift in the incidence of BRAF V600E mutations in PTCs following the 2017 WHO classification and to further characterize the histologic subtypes and molecular drivers in BRAF-negative cases. The study cohort consisted of 554 consecutive PTCs larger than 0.5 cm between January 2019 and May 2022. Immunohistochemistry for BRAF VE1 was performed for all cases. Compared with a historical cohort of 509 PTCs from November 2013 to April 2018, the incidence of BRAF V600E mutations was significantly higher in the study cohort (86.8% vs 78.8%, P = .0006). Targeted RNA-based next-generation sequencing using a FusionPlex Pan Solid Tumor v2 panel (ArcherDX) was performed for BRAF-negative PTCs from the study cohort. Eight cribriform-morular thyroid carcinomas and 3 cases with suboptimal RNA quality were excluded from next-generation sequencing. A total of 62 BRAF-negative PTCs were successfully sequenced, including 19 classic follicular predominant PTCs, 16 classic PTCs, 14 infiltrative follicular PTCs, 7 encapsulated follicular PTCs, 3 diffuse sclerosing PTCs, 1 tall cell PTC, 1 solid PTC, and 1 diffuse follicular PTC. Among them, RET fusions were identified in 25 cases, NTRK3 fusions in 13 cases, BRAF fusions in 5 cases including a novel TNS1::BRAF fusion, NRAS Q61R mutations in 3 cases, KRAS Q61K mutations in 2 cases, NTRK1 fusions in 2 cases, an ALK fusion in 1 case, an FGFR1 fusion in 1 case, and an HRAS Q61R mutation in 1 case. No genetic variants, from our commercially employed assay, were detected in the remaining 9 cases. In summary, the incidence of BRAF V600E mutations in PTCs significantly increased from 78.8% to 86.8% in our post-2017 WHO classification cohort. RAS mutations accounted for only 1.1% of the cases. Driver gene fusions were identified in 8.5% of PTCs and were clinically relevant given the emerging targeted kinase inhibitor therapy. Of the 1.6% of cases for which no driver alteration was detected, the specificity of drivers tested and tumor classification require further investigation.

Diagnosis and Management of Tropomyosin Receptor Kinase Fusion-Positive Thyroid Carcinomas: A Review

IMPORTANCE

Thyroid epithelial malignant neoplasms include differentiated thyroid carcinomas (papillary, follicular, and oncocytic), follicular-derived high-grade thyroid carcinomas, and anaplastic and medullary thyroid carcinomas, with additional rarer subtypes. The discovery of neurotrophic tyrosine receptor kinase (NTRK) gene fusions has fostered developments in precision oncology, with the approval of tropomyosin receptor kinase inhibitors (larotrectinib and entrectinib) for patients with solid tumors, including advanced thyroid carcinomas, harboring NTRK gene fusions.

OBSERVATIONS

The relative rarity and diagnostic complexity of NTRK gene fusion events in thyroid carcinoma present several challenges for clinicians, including variable access to robust methodologies for comprehensive NTRK fusion testing and poorly defined algorithms of when to test for such molecular alterations. To address these issues in thyroid carcinoma, 3 consensus meetings of expert oncologists and pathologists were convened to discuss diagnostic challenges and propose a rational diagnostic algorithm. Per the proposed diagnostic algorithm, NTRK gene fusion testing should be considered as part of the initial workup for patients with unresectable, advanced, or high-risk disease as well as following the development of radioiodine-refractory or metastatic disease; testing by DNA or RNA next-generation sequencing is recommended. Detecting the presence of NTRK gene fusions is important to identify patients eligible to receive tropomyosin receptor kinase inhibitor therapy.

CONCLUSIONS AND RELEVANCE

This review provides practical guidance for optimal integration of gene fusion testing, including NTRK gene fusion testing, to inform the clinical management in patients with thyroid carcinoma.

NTRK Fusion in a Cohort of BRAF p. V600E Wild-Type Papillary Thyroid Carcinomas

Owing to the availability of a potent tropomyosin receptor kinase (TRK) inhibitor, it is necessary to develop an effective strategy to identify an enriched population of NTRK fusions in papillary thyroid carcinoma (PTC) in routine diagnostic practice. The reported prevalence of NTRK fusion in a large cohort of PTC is ∼3%. We performed an analysis to refine the characteristic histologic features of PTCs harboring NTRK fusions and further validate the diagnostic utility of pan-TRK immunohistochemistry as a screening tool. In this study, 450 PTCs known to harbor no BRAF p. V600E mutations were screened by pan-TRK immunohistochemistry, and the cases with TRK expression were confirmed by RNA-based next-generation sequencing assay. Eleven NTRK fusion cases were detected (2.4%), and all PTCs were classical subtypes. NTRK1 and NTRK3 were involved in the fusion with 9 different partner genes. Most cases showed similar characteristic histologic findings. Nodular permeative border, multinodular growth with a predominantly follicular pattern, extensive lymphatic invasion, and prominent internodular and intratumoral fibrosis were the characteristic histologic features of NTRK-rearranged PTCs. The ill-defined margins in the ultrasonography findings, which could not be clearly distinguished from the adjacent nontumorous thyroid tissue, were nodular permeative margins in histologic findings. Therefore, preoperative ultrasonographic findings in nodule margins were consistent with the final histologic findings. NTRK1/3 fusion in PTCs showed an overall sensitivity of 100% (95% CI, 71.51%-100%) and specificity of 100% (95% CI, 71.51%-100%) in the 22 cases examined, as confirmed with next-generation sequencing. Our study provides an integrative report of the preoperative ultrasonographic, histologic, immunohistochemical, and molecular features of NTRK-rearranged PTCs. Based on these findings, we propose an algorithmic approach for the stepwise assessment of NTRK fusions in PTCs.

Review article: new treatments for advanced differentiated thyroid cancers and potential mechanisms of drug resistance

The treatment of advanced, radioiodine refractory, differentiated thyroid cancers (RR-DTCs) has undergone major advancements in the last decade, causing a paradigm shift in the management and prognosis of these patients. Better understanding of the molecular drivers of tumorigenesis and access to next generation sequencing of tumors have led to the development and Food and Drug Administration (FDA)-approval of numerous targeted therapies for RR-DTCs, including antiangiogenic multikinase inhibitors, and more recently, fusion-specific kinase inhibitors such as RET inhibitors and NTRK inhibitors. BRAF + MEK inhibitors have also been approved for BRAF-mutated solid tumors and are routinely used in RR-DTCs in many centers. However, none of the currently available treatments are curative, and most patients will ultimately show progression. Current research efforts are therefore focused on identifying resistance mechanisms to tyrosine kinase inhibitors and ways to overcome them. Various novel treatment strategies are under investigation, including immunotherapy, redifferentiation therapy, and second-generation kinase inhibitors. In this review, we will discuss currently available drugs for advanced RR-DTCs, potential mechanisms of drug resistance and future therapeutic avenues.

NTRK fusions in solid tumours: what every pathologist needs to know

Fusions involving the Neurotrophic tropomyosin receptor kinase (NTRK) gene family (NTRK1, NTRK2 and NTRK3) are targetable oncogenic alterations that are found in a diverse range of tumours. There is an increasing demand to identify tumours which harbour these fusions to enable treatment with selective tyrosine kinase inhibitors such as larotrectinib and entrectinib. NTRK fusions occur in a wide range of tumours including rare tumours such as infantile fibrosarcoma and secretory carcinomas of the salivary gland and breast, as well as at low frequencies in more common tumours including melanoma, colorectal, thyroid and lung carcinomas. Identifying NTRK fusions is a challenging task given the different genetic mechanisms underlying NTRK fusions, their varying frequency across different tumour types, complicated by other factors such as tissue availability, optimal detection methods, accessibility and costs of testing methods. Pathologists play a key role in navigating through these complexities by determining optimal approaches to NTRK testing which has important therapeutic and prognostic implications. This review provides an overview of tumours harbouring NTRK fusions, the importance of identifying these fusions, available testing methods including advantages and limitations, and generalised and tumour-specific approaches to testing.

Molecular and cytogenetic features of NTRK fusions enriched in BRAF and RET double-negative papillary thyroid cancer

Rare NTRK-driven malignant neoplasms can be effectively inhibited by anti-TRK agents. The discovery of NTRK1/2/3-rich tumours in papillary thyroid cancer (PTC) patients is a precondition for the rapid identification of NTRK fusion tumours. Knowledge of NTRK gene activation is critical to accurately detect NTRK status. A total of 229 BRAF V600E-negative samples from PTC patients were analysed in this study. Break-apart fluorescence in situ hybridisation (FISH) was performed to detect RET fusion. NTRK status was analysed using FISH, DNA- and RNA-based next-generation sequencing (NGS), and quantitative reverse transcription-polymerase chain reaction (RT-qPCR). In 128 BRAF and RET double-negative cases, 56 (43.8%, 56/128) NTRK rearrangement tumours were found, including 1 NTRK2, 16 NTRK1, and 39 NTRK3 fusions. Two novel NTRK fusions, EZR::NTRK1 and EML4::NTRK2, was found in the NTRK rearrangement tumors.Dominant break-apart and extra 3' signal patterns accounted for 89.3% (50/56) and 5.4% (3/56) of all NTRK-positive cases, respectively, as determined by FISH. In our cohort, there were 2.3% (3/128) FISH false-negative and 3.1% (4/128) FISH false-positive cases identified. NTRK fusions are highly recurrent in BRAF and RET double-negative PTCs. FISH or RNA-based NGS is a reliable detection approach. NTRK rearrangement can be precisely, rapidly, and economically detected based on the developed optimal algorithm.

Thyroid Nodules and Follicular Cell-Derived Thyroid Carcinomas in Children

Although pediatric thyroid tumors have many similarities to those occurring in adults, significant differences are also recognized. For example, although thyroid nodules in children are much less common than in adults, a higher percentage is malignant. Moreover, while pediatric papillary thyroid carcinoma (PTC) is associated with more advanced disease, death due to disease in children and adolescents is very rare, even when distant metastases are present. Some subtypes of thyroid carcinoma, like diffuse sclerosing variant, are especially common in children and adolescents. Moreover, certain histologic findings, such as a tall cell morphology or increased mitotic activity, may not carry the same prognostic significance in children as in adults. Recent studies exploring the molecular underpinnings of pediatric thyroid carcinoma indicate that while driver alterations of thyroid tumorigenesis in children and adults are essentially the same, they occur at very different frequencies, with translocation-associated tumors (most commonly harboring RET and NTRK fusions) comprising a sizable and distinct group of pediatric PTC. DICER1 mutations, an infrequent mutation in adult thyroid tumors, are relatively frequent in pediatric encapsulated follicular-patterned thyroid tumors (with or without invasion or nuclear features of PTC). Additionally, tumor predisposition syndromes (most notably DICER1 syndrome and PTEN hamartoma tumor syndromes such as Cowden syndrome) should be considered in children with thyroid tumors, especially follicular-patterned thyroid tumors and poorly differentiated thyroid carcinoma. This review will explore the current state of knowledge of thyroid nodules and carcinomas in children and adolescents.

NTRK fusions in thyroid cancer: Pathology and clinical aspects

Thyroid cancer is the most common endocrine cancer. Neurotrophic tyrosine receptor kinase (NTRK) fusions are oncogenic drivers in multiple solid tumors, including thyroid cancer. NTRK fusion thyroid cancer has unique pathological features such as mixed structure, multiple nodes, lymph node metastasis, and a background of chronic lymphocytic thyroiditis. Currently, RNA-based next-generation sequencing is the gold standard for the detection of NTRK fusions. Tropomyosin receptor kinase inhibitors have shown promising efficacy in patients with NTRK fusion-positive thyroid cancer. Efforts to overcome acquired drug resistance are the focus of research concerning next-generation TRK inhibitors. However, there are no authoritative recommendations or standardized procedures for the diagnosis and treatment of NTRK fusions in thyroid cancer. This review discusses current research progress regarding NTRK fusion-positive thyroid cancer, summarizes the clinicopathological features of the disease, and outlines the current statuses of NTRK fusion detection and targeted therapeutic agents.

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.

High-Grade Non-Anaplastic Thyroid Carcinomas of Follicular Cell Origin: A Review of Poorly Differentiated and High-Grade Differentiated Carcinomas

Poorly differentiated thyroid carcinoma (PDTC) and high-grade differentiated thyroid carcinoma (HGDTC) are considered high-grade follicular-derived thyroid carcinomas, with prognoses intermediate between well-differentiated and anaplastic thyroid carcinoma. Both share the presence of invasion, thyroid follicular-cell origin, and tumor necrosis or increased mitoses (≥ 3 mitoses per 2 mm² in PDTC and ≥ 5 mitoses per 2 mm² in HGDTC), without anaplastic dedifferentiation. PDTC must possess solid, trabecular, or insular growth and lack classic papillary-like nuclei; HGDTC can be of any architectural or nuclear morphology (follicular-like, papillary-like, oncocytic). Transformation may be accompanied by acquisition of high-risk mutations (such as TP53 or TERT promoter) on top of RAS-like or BRAF p.V600E-like (including NTRK-fusion) initial driver mutations. These carcinomas most frequently affect adults and often present with metastases (20-50%) or wide local invasion. As PDTC and HGDTC may be radioactive iodine resistant, post-surgical therapy may consist of external beam radiotherapy or targeted, mutation-dependent chemotherapy, such as tyrosine kinase inhibitors. Ten-year disease specific survival is as low as 50%. Awareness of high-grade features in the diagnostic setting is important for patient prognosis and triage of tissue for molecular analysis in order to guide relevant clinical management and therapy.

Entrectinib in the neoadjuvant setting of anaplastic thyroid cancer: a case report

Background

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive solid tumors. ATC is frequently diagnosed at advanced stages with unresectable disease and palliative care is often indicated. Recently, several patient-tailored therapies for ATC are emerging due to advances in molecular profiling of these tumors. Entrectinib is a potent oral selective inhibitor of neutrotrophic tropomyosin receptor kinase (NTRK), ROS1, and anaplastic lymphoma kinase fusions. The experience regarding ATC and other thyroid carcinomas, particularly in the neoadjuvant setting, is minimal.

Case report

We present a case of a 51-year-old female patient presenting with a bulky mass of the left thyroid lobe measuring 100 × 108 × 80 mm that was considered surgically unresectable. While waiting for next-generation sequence (NGS) profiling, lenvatinib was initiated. There was an initial clinical and imagiologic response; however, progression occurred after 12 weeks, and at this time NGS identified an ETV6-NTRK3 fusion and entrectinib was started. After 12 weeks, tumor diameters reduced to a minimum of 68×60×49 mm, and the patient underwent total thyroidectomy plus central lymphadenectomy. Histological diagnosis confirmed an ATC (pT4a R2 N1a). Adjuvant radiotherapy (RT) (60 Grays) with weekly paclitaxel (45 mg/m2) was then administered followed by maintenance entrectinib 600 mg daily. Fluorodeoxyglucose positron emission tomography performed 3 months after completion of RT showed only non-specific uptake in the posterior wall of the hypopharynx and larynx, suggestive of inflammation.

Conclusion

We report the first case of an ATC with a dramatic response to neoadjuvant therapy with entrectinib, which enabled surgical resection of an ab initio unresectable tumor.

Molecular and clinical features of papillary thyroid cancer in adult patients with a non-classical phenotype

Purpose

Genotyping is fundamental in papillary thyroid cancer (PTC) and helps to enhance diagnosis and prognosis and determine appropriate treatments. The phenotype-genotype association in PTC was previously studied, with BRAF V600E characterizing classic PTC and tall-cell PTC and RAS mutations characterizing follicular-variant PTC. In clinic, some non-classical histological subtypes of PTC were also identified, however, their genotype remains unclear. In this study, we collected samples of these non-classical PTC after the exclusion of classic phenotypes and examined their phenotypes, genotype and the relationship between phenotype and genotype.

Methods

We screened out non-classical PTC by excluding classical PTC from 1,059 different thyroid samples, and a total of 24 cases was obtained and described from the morphological features, which is rare in differentiated PTC. DNA/RNA sequencing was performed using 18 available samples to describe the genetic features.

Results

PTC with the non-classical phenotype were characterized cuboidal to low columnar tumor cells with subtle nuclear features of PTC and without discernible nuclear elongation, concurrently with dense microfollicles, delicate papillae or solid nodules with delicate fibrovascular cores. They were associated with lymphatic vessel invasion (P<0.001) but not with a worse prognosis (P=0.791). Gene fusions were identified in 14 of 18 (77.8%) cases, including eight fusions of NTRK and six fusions of RET. The high percentage of fusions in this papillary thyroid cancer subgroup suggested a correlation of gene fusions with the phenotype that does not belong to the BRAF V600E-mutant or RAS-mutant group.

Conclusions

Our study retrospectively screened a large cohort of different thyroid tissue samples, and presented the histopathological and genetic features of a non-classical phenotype of PTC from 24 patients. It may contribute to diagnose in PTC, and patients of these non-classical phenotype may benefit from targeted therapy, compared to a natural patient cohort without selection.

Case report: EML4::NTRK3 gene fusion in a patient with metastatic lung adenocarcinoma successfully treated with entrectinib

Rearrangements involving the neurotrophin kinase (NTRK) genes NTRK1, NTRK2 and NTRK3 with different fusion partners have been observed in both adult and pediatric solid tumors. Larotrectinib and entrectinib have been the first tumor-agnostic compounds approved for the treatment of NTRK fusion-positive tumors. Here, we report the first case of a female patient with a diagnosis of stage IV lung adenocarcinoma harboring the EML4::NTRK3 gene fusion, and successfully treated with entrectinib.

Advancement of secretory breast carcinoma: a narrative review

BACKGROUND AND OBJECTIVE

Secretory breast carcinoma (SBC) is a rare breast malignancy. Most available studies on SBC are case reports or small case series, and the few large-sample studies available lack critical information due to database limitations. To improve the understanding of SBC and provide a reference for clinical practice, we systematically reviewed the demographic, clinical, pathologic, and genetic characteristics of SBC, as well as its treatment and prognosis.

METHODS

We conducted a PubMed search with the keywords "secretory breast carcinoma" or "juvenile breast carcinoma". Relevant English-language publications published from January 1966 to February 2022 were screened manually at 3 levels-title, abstract, and full text-to identify the articles that presented the demographic, clinical, pathologic, and genetic characteristics of SBC, as well as its treatment and prognosis.

KEY CONTENT AND FINDINGS

SBC lacks specific clinical manifestations and has typical pathological and molecular characteristics, including intracellular and extracellular eosinophilic secretions, immune spectrum similar to hormone receptor-positive tumors, and the ETV6-NTRK3 fusion gene. Surgery remains the primary treatment for SBC. Postoperative radiotherapy is recommended by most researchers for adult SBC but not for pediatric patients. The evidence of chemotherapy and endocrine therapy is insufficient, and targeted therapy of the ETV6-NTRK3 fusion gene shows a good response. Most patients with SBC have a good prognosis except for a few patients who experience distant metastases. Future studies will be focused on the molecular characteristics of those patients with SBC who have a poor prognosis.

CONCLUSIONS

The development of histopathology and molecular genetics has promoted the progress of the clinical diagnosis of SBC. The purpose of this review is to serve as a guide for the better clinical treatment of SBC, particularly in the areas of disease identification and prognosis classification for patients.

Efficacy and safety of multi-kinase inhibitors in patients with radioiodine-refractory differentiated thyroid cancer: a systematic review and meta-analysis of clinical trials

OBJECTIVES

Radioiodine-refractory differentiated thyroid cancer (RAI-rDTC) has frequently been associated with poor prognosis. We conducted a meta-analysis of published randomized controlled trials to evaluate multi-kinase inhibitors' efficacy and safety profile treatment.

METHODS

A comprehensive search was conducted using PubMed, Embase, Cochrane, and Medline databases. The quality of literature and trial risk of bias was assessed using the Cochrane risk of bias tool, while the results of progression-free survival (PFS), overall survival (OS), and adverse events (AEs) were evaluated using RevMan5.3 software.

RESULTS

A total of 1384 patients in six studies met the criteria. Treatment with MKIs significantly improved PFS and OS, but AEs were significantly higher than those in the control group (P<0.01). The studies demonstrated the median PFS (HR 0.30, 95% CI: 0.18-0.50, P <0.00001) and OS (HR 0.70, 95% CI: 0.57-0.88, P=0.002) in RAI-rDTC patients treated with MKIs, and the median PFS of papillary thyroid carcinoma (HR0.28, 95% CI: 0.22-0.37, P<0.00001) along with follicular thyroid carcinoma (HR0.14, 95%CI 0.09-0.24, P<0.00001) were extended.

CONCLUSION

MKIs significantly prolonged PFS and OS in patients with RAI-rDTC (P<0.01). Our recommendation is to use MKIs carefully in patients after evaluating their health status to maximize treatment benefits and minimize adverse effects.

Efficacy and safety of larotrectinib in patients with TRK fusion-positive thyroid carcinoma

OBJECTIVE

Larotrectinib is a highly selective tropomyosin receptor kinase (TRK) inhibitor with demonstrated efficacy across various TRK fusion-positive solid tumours. We assessed the efficacy and safety of larotrectinib in patients with TRK fusion-positive thyroid carcinoma (TC).

METHODS

We pooled data from three phase I/II larotrectinib clinical trials (NCT02576431, NCT02122913, and NCT02637687). The primary endpoint was the investigator-assessed objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors v1.1. Secondary endpoints included duration of response (DoR), progression-free survival (PFS), overall survival (OS), and safety. Data cut-off: July 2020.

RESULTS

Twenty-nine patients (median age: 60; range: 6-80) with TRK fusion-positive TC were treated. Tumour histology was papillary (PTC) in 20 (69%) patients, follicular (FTC) in 2 (7%), and anaplastic (ATC) in 7 (24%) patients. Among 28 evaluable patients, ORR was 71% (95% CI: 51-87); best responses were complete response in 2 (7%) patients, partial response in 18 (64%), stable disease in 4 (14%), progressive disease in 3 (11%), and undetermined in 1 (4%) due to clinical progression prior to the first post-baseline assessment. ORR was 86% (95% CI: 64-97) for PTC/FTC and 29% (95% CI 4-71) for ATC. Median time to response was 1.87 months (range 1.64-3.68). The 24-month DoR, PFS, and OS rates were 81, 69, and 76%, respectively. Treatment-related adverse events were mainly grades 1-2.

CONCLUSION

In TRK fusion-positive TC, larotrectinib demonstrates rapid and durable disease control and a favourable safety profile in patients with advanced disease requiring systemic therapy.

SIGNIFICANCE STATEMENT

NTRK gene fusions are known oncogenic drivers and have been identified in various histologies of thyroid carcinoma, most commonly in papillary thyroid carcinoma. This is the first publication specifically studying a TRK inhibitor in a cohort of TRK fusion-positive thyroid carcinoma patients. In the current study, the highly selective TRK inhibitor larotrectinib showed durable antitumour efficacy and a favourable safety profile in patients with TRK fusion-positive thyroid carcinoma. Our findings show that patients with advanced non-medullary thyroid carcinoma who may require systemic therapy could be considered for testing for gene fusions by next-generation sequencing.

The clinical aspect of NTRK-fusions in pediatric papillary thyroid cancer

Although adult and pediatric papillary thyroid cancer (PTC) share similar oncogenic drivers, they differ in the pathological features and outcomes of the disease. In adults with PTC, the most frequent genetic alterations are mutually exclusive point mutations in BRAFV600E or the RAS family with BRAFV600E commonly associated with invasive disease and decreased response to radioiodine therapy. In pediatric PTC, fusion oncogenes involving chromosomal translocations in tyrosine kinase (TK) receptors, most commonly RET and NTRK, are often found in patients with lateral neck and distant metastases. This brief report reviews clinical data from a single-institute's cohort of NTRK-driven pediatric PTC cases with an updated review of the literature and comparison to adult NTRK-driven PTC.

Expanding the Spectrum of Adult NTRK3-Rearranged Spindle Cell Neoplasms: A Recurrent NTRK3-SQSTM1 Fusion Spindle Cell Tumor With Deceptively Bland Morphology

OBJECTIVES

NTRK-rearranged spindle cell neoplasms (other than infantile fibrosarcoma) are an emerging entity of tumors that demonstrate wide variation in clinical and histopathologic features. We report a case of an NTRK-rearranged spindle cell neoplasm bearing a deceptively bland morphology.

METHODS

We performed histopathologic, immunohistochemical, and molecular evaluation on resection tissue. We also conducted a literature review on adult NTRK3-rearranged spindle cell neoplasms.

RESULTS

The tumor presented as a recurrent ankle mass in an elderly patient. Histologically, it was composed of bland spindle cells set in a fibrous to edematous stroma. Blood vessels were interspersed with subtle perivascular hyalinization and scattered lymphoid aggregates. Immunohistochemically, the spindle cells expressed CD34 and S100 while being negative for SOX10. The tumor also showed cytoplasmic reactivity for pan-tyrosine receptor kinase immunohistochemistry. Next-generation sequencing identified an NTRK3-SQSTM1 fusion. To the best of our knowledge, this fusion pair has not been previously reported in adult NTRK-rearranged mesenchymal tumors.

CONCLUSIONS

Altogether, this rare and diagnostically challenging case of an NTRK3-rearranged spindle cell tumor with low-grade morphology is in contrast to many of the reported adult NTRK3-rearranged mesenchymal tumors. Recognition of low-grade NTRK-rearranged tumors demands close attention to clues in morphology and immunoprofiles.

Detection of NTRK Fusions and TRK Expression and Performance of pan-TRK Immunohistochemistry in Routine Diagnostics: Results from a Nationwide Community-Based Cohort

Gene fusions involving NTRK1, NTRK2, and NTRK3 are rare drivers of cancer that can be targeted with histology-agnostic inhibitors. This study aimed to determine the nationwide landscape of NTRK/TRK testing in the Netherlands and the usage of pan-TRK immunohistochemistry (IHC) as a preselection tool to detect NTRK fusions. All pathology reports in 2017–2020 containing the search term ‘TRK’ were retrieved from the Dutch Pathology Registry (PALGA). Patient characteristics, tumor histology, NTRK/TRK testing methods, and reported results were extracted. NTRK/TRK testing was reported for 7457 tumors. Absolute testing rates increased from 815 (2017) to 3380 (2020). Tumors were tested with DNA/RNA-based molecular assay(s) (48%), IHC (47%), or in combination (5%). A total of 69 fusions involving NTRK1 (n = 22), NTRK2 (n = 6) and NTRK3 (n = 41) were identified in tumors from adult (n = 51) and pediatric (n = 18) patients. In patients tested with both IHC and a molecular assay (n = 327, of which 29 NTRK fusion-positive), pan-TRK IHC had a sensitivity of 77% (95% confidence interval (CI), 56–91) and a specificity of 84% (95% CI, 78–88%). These results showed that pan-TRK IHC has a low sensitivity in current routine practice and warrants the introduction of quality guidelines regarding the implementation and interpretation of pan-TRK IHC.

Overview of the 2022 WHO Classification of Thyroid Neoplasms

This review summarizes the changes in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors that relate to the thyroid gland. The new classification has divided thyroid tumors into several new categories that allow for a clearer understanding of the cell of origin, pathologic features (cytopathology and histopathology), molecular classification, and biological behavior. Follicular cell-derived tumors constitute the majority of thyroid neoplasms. In this new classification, they are divided into benign, low-risk, and malignant neoplasms. Benign tumors include not only follicular adenoma but also variants of adenoma that are of diagnostic and clinical significance, including the ones with papillary architecture, which are often hyperfunctional and oncocytic adenomas. For the first time, there is a detailed account of the multifocal hyperplastic/neoplastic lesions that commonly occur in the clinical setting of multinodular goiter; the term thyroid follicular nodular disease (FND) achieved consensus as the best to describe this enigmatic entity. Low-risk follicular cell-derived neoplasms include non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), thyroid tumors of uncertain malignant potential, and hyalinizing trabecular tumor. Malignant follicular cell-derived neoplasms are stratified based on molecular profiles and aggressiveness. Papillary thyroid carcinomas (PTCs), with many morphological subtypes, represent the BRAF-like malignancies, whereas invasive encapsulated follicular variant PTC and follicular thyroid carcinoma represent the RAS-like malignancies. This new classification requires detailed subtyping of papillary microcarcinomas similar to their counterparts that exceed 1.0 cm and recommends not designating them as a subtype of PTC. The criteria of the tall cell subtype of PTC have been revisited. Cribriform-morular thyroid carcinoma is no longer classified as a subtype of PTC. The term "Hürthle cell" is discouraged, since it is a misnomer. Oncocytic carcinoma is discussed as a distinct entity with the clear recognition that it refers to oncocytic follicular cell-derived neoplasms (composed of > 75% oncocytic cells) that lack characteristic nuclear features of PTC (those would be oncocytic PTCs) and high-grade features (necrosis and ≥ 5 mitoses per 2 mm²). High-grade follicular cell-derived malignancies now include both the traditional poorly differentiated carcinoma as well as high-grade differentiated thyroid carcinomas, since both are characterized by increased mitotic activity and tumor necrosis without anaplastic histology and clinically behave in a similar manner. Anaplastic thyroid carcinoma remains the most undifferentiated form; squamous cell carcinoma of the thyroid is now considered as a subtype of anaplastic carcinoma. Medullary thyroid carcinomas derived from thyroid C cells retain their distinct section, and there is a separate section for mixed tumors composed of both C cells and any follicular cell-derived malignancy. A grading system for medullary thyroid carcinomas is also introduced based on mitotic count, tumor necrosis, and Ki67 labeling index. A number of unusual neoplasms that occur in the thyroid have been placed into new sections based on their cytogenesis. Mucoepidermoid carcinoma and secretory carcinoma of the salivary gland type are now included in one section classified as "salivary gland-type carcinomas of the thyroid." Thymomas, thymic carcinomas and spindle epithelial tumor with thymus-like elements are classified as "thymic tumors within the thyroid." There remain several tumors whose cell lineage is unclear, and they are listed as such; these include sclerosing mucoepidermoid carcinoma with eosinophilia and cribriform-morular thyroid carcinoma. Another important addition is thyroblastoma, an unusual embryonal tumor associated with DICER1 mutations. As in all the WHO books in the 5th edition, mesenchymal and stromal tumors, hematolymphoid neoplasms, germ cell tumors, and metastatic malignancies are discussed separately. The current classification also emphasizes the value of biomarkers that may aid diagnosis and provide prognostic information.

Cytological and molecular characterization of secretory breast carcinoma

Secretory breast carcinoma is a rare neoplasm, histologically well-characterized, and secondary to ETV6-NTRK3 gene fusion, whose cytological features are scarcely described in the literature. We report the case of a woman with a history of secretory breast carcinoma 8 years before, who presented a periareolar nodule. A recurrence was diagnosed by fine-needle aspiration based on the cytomorphological features and pan-TRK immunocytochemistry on the cell block, and the patient underwent a mastectomy. The histology and molecular studies performed on the surgical specimen (immunohistochemistry, FISH and NGS) confirmed the diagnosis. Cytological smears showed abundant epithelial cellularity, in groups and single cells. These cells showed moderate atypia, with abundant cytoplasm. We observed intracytoplasmic inclusions and extracellular metachromatic globules. Immunocytochemical and immunohistochemical studies showed a triple negative breast tumour. NTRK overexpression was demonstrated with immunocytochemistry against pan-TRK on the cell block, as well as with immunohistochemistry in the surgical specimen. NTRK3 rearrangement was proved by FISH. In the primary tumour and in the recurrence, we demonstrated ETV6-NTRK3 fusion by NGS. After conducting a literature review, we have found 26 articles describing the cytological features of secretory breast carcinoma in 33 patients. The smears were described as groups of epithelial cells with vacuolated cytoplasm, single signet ring cells and a globular extracellular secretion. In only two cases molecular confirmation of the diagnosis with ETV6-NTRK3 fusion was proven, although not in the cytological specimen, but in the subsequent biopsy. The distinct cytological features of secretory breast carcinoma can help in its diagnosis, thus guiding the molecular studies. This is the first reported case that proves TRK overexpression, as a fusion surrogate, in the cytological sample.

Therapeutic avenues for cancer neuroscience: translational frontiers and clinical opportunities

With increasing attention on the essential roles of the tumour microenvironment in recent years, the nervous system has emerged as a novel and crucial facilitator of cancer growth. In this Review, we describe the foundational, translational, and clinical advances illustrating how nerves contribute to tumour proliferation, stress adaptation, immunomodulation, metastasis, electrical hyperactivity and seizures, and neuropathic pain. Collectively, this expanding knowledge base reveals multiple therapeutic avenues for cancer neuroscience that warrant further exploration in clinical studies. We discuss the available clinical data, including ongoing trials investigating novel agents targeting the tumour-nerve axis, and the therapeutic potential for repurposing existing neuroactive drugs as an anti-cancer approach, particularly in combination with established treatment regimens. Lastly, we discuss the clinical challenges of these treatment strategies and highlight unanswered questions and future directions in the burgeoning field of cancer neuroscience.

Systematic population-based identification of NTRK and RET fusion-positive thyroid cancers

Objective

The aim of the study was to identify patients with NTRK fusion-positive or RET fusion/mutation-positive thyroid cancers, who could benefit from neurotrophic tyrosine kinase receptor (NTRK) or receptor tyrosine kinase (RET) inhibitors.

Methods

Patients were identified in the Calgary prospective thyroid cancer database (N= 482). Patients were 'pre-screened' with clinically available MassARRAY® BRAF test, Colon Panel, Melanoma Panel, or ThyroSPEC™. Mutation-negative tumors were 'screened' for NTRK fusions and RET fusions/mutations with the Oncomine™ Comprehensive Assay v3 (OCAv3).

Results

A total of 86 patients were included in 1 of 2 separate analyses. Analysis A included 42 patients with radioactive iodine (RAI)-resistant distant metastases. After pre-screening, 20 BRAF and RAS mutation-negative patients underwent OCAv3 screening, resulting in the detection of 4 patients with NTRKfusions and 4 patients with RET fusions (8/20, 40% of analyzed patients). Analysis B included 44 patients, 42 with American Thyroid Association (ATA) high and intermediate risk of recurrence and 2 with medullary thyroid carcinoma. During pre-screening, 1 patient with an NTRK fusion, 1 patient with a RET fusion, and 30 patients with BRAF mutations were identified. The remaining 9 patients received OCAv3 screening, resulting in detection of 1 patient with an NTRKfusion and 1 with a RET fusion (4/11, 36% of analyzed patients).

Conclusions

Our findings indicate a higher rate of NTRK fusions and RETfusions in patients with thyroid cancer with RAI-resistant distant metastases and ATA high or intermediate risk of recurrence. This highlights the importance of early screening to enable intervention with a NTRK or RET inhibitor.

Multiple endocrine neoplasia type 1 combined with thyroid neoplasm: A case report and review of literatures

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN1) is a rare hereditary tumor syndrome inherited in an autosomal dominant manner and presents mostly as parathyroid, endocrine pancreas (such as gastrinoma) and anterior pituitary tumors. At present, papillary thyroid carcinoma (PTC) and nodular goiter are not regarded as components of MEN1.

CASE SUMMARY

A 35-year-old woman presented with MEN1 accompanied by coinstantaneous PTC and nodular goiter. The pathological diagnosis was PTC with cervical lymph node metastasis, nodular goiter, parathyroid cyst and adenomatoid hyperplasia. Genetic testing was performed and a MEN1 gene mutation was detected. The patient underwent unilateral lobectomy of the thyroid gland and surgical removal of the parathyroid tumors. At 18 mo of follow-up, ultrasonic examination of the neck showed no abnormality. Serum calcium and parathyroid hormone levels were normal. No new MEN1-associated tumors were detected.

CONCLUSION

The role of inactivating mutations of MEN1 gene in tumorigenesis of PTC and/or nodular goiter remains to be determined by more case reports and further research.

Emerging Biomarkers in Thyroid Practice and Research

Simple Summary

Tumor biomarkers are molecules at genetic or protein level, or certain evaluable characteristics. These help in perfecting patient management. Over the past decade, advanced and more sensitive techniques have led to the identification of many new biomarkers in the field of oncology. A knowledge of the recent developments is essential for their application to clinical practice, and furthering research. This review provides a comprehensive account of such various markers identified in thyroid carcinoma, the most common endocrine malignancy. While some of these have been brought into use in routine patient management, others are novel and need more research before clinical application.

Abstract

Thyroid cancer is the most common endocrine malignancy. Recent developments in molecular biological techniques have led to a better understanding of the pathogenesis and clinical behavior of thyroid neoplasms. This has culminated in the updating of thyroid tumor classification, including the re-categorization of existing and introduction of new entities. In this review, we discuss various molecular biomarkers possessing diagnostic, prognostic, predictive and therapeutic roles in thyroid cancer. A comprehensive account of epigenetic dysregulation, including DNA methylation, the function of various microRNAs and long non-coding RNAs, germline mutations determining familial occurrence of medullary and non-medullary thyroid carcinoma, and single nucleotide polymorphisms predisposed to thyroid tumorigenesis has been provided. In addition to novel immunohistochemical markers, including those for neuroendocrine differentiation, and next-generation immunohistochemistry (BRAF V600E, RAS, TRK, and ALK), the relevance of well-established markers, such as Ki-67, in current clinical practice has also been discussed. A tumor microenvironment (PD-L1, CD markers) and its influence in predicting responses to immunotherapy in thyroid cancer and the expanding arena of techniques, including liquid biopsy based on circulating nucleic acids and plasma-derived exosomes as a non-invasive technique for patient management, are also summarized.

Belgian expert consensus for tumor-agnostic treatment of NTRK gene fusion-driven solid tumors with larotrectinib

Fusions of NTRK (neurotrophic tyrosine receptor kinase) genes with 5' partner genes can result in the expression of chimeric proteins that drive oncogenesis through ligand-independent kinase activation. Despite variable frequencies of NTRK fusions in different tumor types, the fact that they are common to a wide range of cancers raises the possibility of developing tumor-agnostic treatments specifically targeting NTRK fusion products, irrespective of tumor type. The first-generation Trk (tropomyosin receptor kinase) inhibitor, larotrectinib, was the first tumor-agnostic treatment of NTRK fusion-positive cancers in adults and children, to be approved in the European Union. This consensus, developed by a Belgian multidisciplinary expert panel, aims to highlight the unmet medical need associated to NTRK fusion-driven cancer treatment and, based on current knowledge of NTRK fusions and larotrectinib treatment outcome and safety, provide comprehensive guidance to oncologists regarding NTRK fusion-driven cancer diagnostics and the best use of larotrectinib in real-world clinical settings. Larotrectinib; NTRK gene fusion; Trk inhibitor; Tumor-agnostic; Expert opinion; Oncogene proteins; Protein kinase inhibitors.

NTRK-Rearranged soft tissue neoplasms: A review of evolving diagnostic entities and algorithmic detection methods

The spectrum of tumors with NTRK1/2/3 rearrangements has expanded with widespread use of next generation sequencing (NGS) technology. For many years it was known that a majority of infantile fibrosarcomas (IFS), and their counterpart in the kidney, cellular congenital mesoblastic nephroma, contain the recurrent ETV6-NTRK3 fusion. Sequencing RNA transcripts from IFS and their morphologically similar counterparts in older children and adults has shown rearrangements with other 5' partners combined with NTRK1, NTRK2, and NTRK3 can also occur. For those tumors occurring outside of the infant age group, this has resulted in a proposed new diagnostic entity of "NTRK-rearranged spindle cell neoplasm." The clinical behavior of NTRK rearranged soft tissue tumors varies, though most show localized disease with rare metastases. The pathology of NTRK rearranged tumors exists on a spectrum, with overlapping features of classic infantile fibrosarcoma, lipofibromatosis, and malignant peripheral nerve sheath tumor. In this tumor spectrum, clinical and pathologic predictive factors are largely still to be determined, with no clear association between histologic grade and severity of disease. Of critical importance is detection of the NTRK rearrangement in order to guide treatment in patients with unresectable and metastatic disease. While resection is the definitive treatment, these tumors do show response to targeted TRK kinase inhibitors. Multiple detection methods are available, including immunohistochemistry, FISH, and next generation sequencing, which each have their merits and potential pitfalls. We aim to review the clinical characteristics and histomorphology of mesenchymal tumors with NTRK rearrangements as well as discuss molecular detection methods and diagnostic algorithms specific for soft tissue tumors.

Novel Inhibitor-Based Therapies for Thyroid Cancer-An Update

Thyroid cancers (TCs) are the most common tumors of the endocrine system and a constant rise in the number of TC cases has been observed for the past few decades. TCs are one of the most frequent tumors in younger adults, especially in women, therefore early diagnosis and effective therapy are especially important. Ultrasonography examination followed by fine needle biopsy have become the gold standard for diagnosis of TCs, as these strategies allow for early-stage detection and aid accurate qualification for further procedures, including surgical treatment. Despite all the advancements in detection and treatment of TCs, constant mortality levels are still observed. Therefore, a novel generation line of targeted treatment strategies is being developed, including personalized therapies with kinase inhibitors. Recent molecular studies on TCs demonstrate that kinase inhibitor-based therapies might be considered as the most promising. In the past decade, new kinase inhibitors with different mechanisms of action have been reported and approved for clinical trials. This review presents an up-to-date picture of new approaches and challenges of inhibitor-based therapies in treatment of TCs, focusing on the latest findings reported over the past two years.