Characterization of novel genetic alterations in salivary gland secretory carcinoma

Heterogeneity in benign and malignant salivary gland tumors

Advanced proteomics tools have identified the role of proteins in cancer biology, highlighting the importance of these molecules for biomarker discovery and providing valuable insights into cancer diagnosis, prognosis, and targeted therapy. Proteome analysis of tissue using high-throughput proteomics techniques has identified proteins associated with recurrence and malignant transformation in benign tumors, and protein profiling of fine needle aspiration has revealed potential biomarkers for distinguishing malignant salivary gland tumors from benign ones. In addition, proteomics studies have identified distinct protein expression patterns in mesenchymal stem cells derived from malignant salivary gland tumors, suggesting a potential role for proteins in adverse behavior and/or targeted therapy. To provide a comprehensive knowledge of salivary gland tumors, this review will first provide a brief description of the molecular and cellular alterations in common benign and malignant salivary gland tumors and then describe the proteomics studies by concentration on different biological sources including serum/plasma, saliva, tumor tissues and related derivatives (e.g. mesenchymal stem cells, tumor cells, tumor established cell lines, and fine needle aspiration), and introduce potential targets for diagnosis, prognosis, and cancer therapy.

PRSS3 is a potential prognostic biomarker for lung adenocarcinoma

Background

Lung adenocarcinoma (LUAD) is a highly prevalent and deadly form of lung cancer and is a significant health concern worldwide. Although the expression of serine protease 3 (PRSS3) is elevated in certain cancers, its function in LUAD is yet unclear. The aim of this study was to investigate the mechanism of PRSS3 in lung adenocarcinoma, and validate PRSS3 as a reliable prognostic biomarker in lung adenocarcinoma.

Methods

The Cancer Genome Atlas (TCGA) provides RNA expression data and patient medical information for LUAD patients. To determine which genes are expressed differently in LUAD and normal lung tissues, we carefully examined these data. We then used Cox regression analysis to examine the expression and survival data to pinpoint the genes that are strongly associated with patient survival. The PRSS3 gene affects patient prognosis. Afterward, we divided LUAD patients into low- and high-expression groups on the basis of the median PRSS3 expression to examine the relationship between immune cells and PRSS3. The results of the CIBERSORT and CIBERSORTx studies revealed correlations between PRSS3 and the degree of infiltration of several immune cell types. After the groups with low and high PRSS3 expressions were compared, PRSS3-related genes were identified, and functional enrichment analysis was performed. Furthermore, a model was developed to predict patient prognosis according to clinical characteristics and PRSS3 expression. After the bioinformatics analyses were completed, we validated the differential expression of PRSS3 in samples obtained from our center via Western blotting and immunohistochemistry (IHC).

Results

We found that PRSS3 expression is highly upregulated in LUAD and that high PRSS3 expression is associated with a poorer prognosis in the TCGA database. Single-sample gene enrichment analysis revealed a strong correlation between PRSS3 and the immunological microenvironment. The clinical model developed on the basis of the PRSS3 showed great accuracy and can be used as a significant diagnostic indicator for LUAD. Western blotting and IHC confirmed a substantial increase in PRSS3 expression in LUAD. Herein, we analyzed an available dataset for a clinical cohort and revealed that elevated levels of PRSS3 are indicative of unfavorable outcomes in patients diagnosed with LUAD.

Conclusions

PRSS3 is significantly upregulated in LUAD and can be used as a marker for LUAD diagnosis and prognosis assessment. Further study of PRSS3 could provide valuable insight into the mechanisms underlying the occurrence and progression of LUAD.

Role of Ancillary Techniques in the Differential Diagnosis of Salivary Gland Carcinomas

Paiva-Correia A, Hellquist H, Apolónio J, Castelo-Branco P. Role of ancillary techniques in the differential diagnosis of salivary gland carcinomas. The diagnosis of salivary gland carcinomas (SGC) rests mainly on histology, but immunohistochemical and molecular investigations are often necessary for differential diagnosis. This review is primarily aimed as a tool for pathologists in non-specialised head and neck hospitals who encounter a limited number of SGC annually. The use of testing an initial antibody panel, which may comprise both positive and negative expression for a suspected entity, and examples of different panels are outlined. We also focused on acinic cell carcinoma (AcCC), which is positive for DOG1 and negative for mammaglobin, whilst secretory carcinoma (SC) is positive for mammaglobin and negative for DOG1. In addition, the exclusive expression of androgen and HER2 in salivary duct carcinoma (SDC) and its use for differential diagnosis are also addressed. This review also highlights the particularities of mucoepidermoid carcinoma (MEC) and its negativity for S100 and SOX10, which distinguishes it from some of its mimics. In laboratories with limited access to antibodies for SGC, we recommend inclusion of mammaglobin. The use of molecular techniques for the diagnosis of MEC (MAML2), SC (ETV6), adenoid cystic carcinoma (MYB), and AcCC (NR4A3) is discussed. We highlight the role of commonly available antibodies for the histological classification of SGC.

Molecular landscape of salivary gland malignancies. What is already known?

Salivary gland carcinomas (SGCs) are highly heterogeneous histopathological entities that arise in either the major or minor salivary glands. Although uncommon, these tumours exhibit considerable aggressiveness, unpredictable progression, and significant mortality. The fifth edition of the World Health Organisation classification of head and neck tumours distinguishes between 24 salivary gland malignancies. This may lead to difficulties in terms of diagnostic accuracy and suitable therapeutic selection. Mucoepidermoid carcinoma occurs most frequently and is characterised by gradual disease progression. Although salivary duct carcinoma, myoepithelial carcinoma, and carcinoma ex pleomorphic adenoma are rarely detected, they contribute to poor patient outcomes. Currently, attempts have been made to establish molecular characterisation of SGCs to improve differential diagnosis and create targeted treatments. This study aimed to summarise current knowledge regarding genetic variations in the most common salivary gland malignancies.

Acinic cell Carcinoma with high-grade Squamoglandular and Chondrosarcomatous Transformation Mimicking 'Carcinosarcoma ex-pleomorphic Adenoma': A Wrinkle in the Proposed Nomenclature Revision for Sarcomatoid Salivary Gland Neoplasms

While acinic cell carcinoma (AciCC) can undergo high-grade transformation (HGT) to high-grade adenocarcinoma or poorly differentiated carcinoma, other morphologies such as spindle cell/sarcomatoid carcinoma are rare and not well-characterized. We herein report a novel case of AciCC with squamoglandular and chondrosarcomatous HGT mimicking a so-called 'carcinosarcoma ex-pleomorphic adenoma'. The patient is an 81-year-old male with a two-month history of neck swelling and referred otalgia who presented with a left parapharyngeal space mass extending into retropharyngeal space and pterygoid muscles. On resection, the tumor showed considerable morphologic diversity with high-grade serous and mucous acinar components as well as cribriform to solid apocrine-like components with comedonecrosis and squamous differentiation, all of which were embedded in a chondromyxoid background ranging from paucicellular and bland to a high-grade chondrosarcoma/pleomorphic sarcoma-like appearance. Only a minor conventional AciCC component was noted. Immunostains were negative for AR and only focally positive for GCDFP-15 arguing against a true apocrine phenotype, while PLAG1 and HMGA2 were negative arguing against an antecedent pleomorphic adenoma. On the other hand, SOX-10, DOG-1 and PAS after diastase highlighted serous acinar differentiation, and mucicarmine, and NKX3.1 highlighted mucous acinar differentiation. NR4A3 immunohistochemical staining and NR4A3 fluorescence in situ hybridization were positive in the carcinomatous and sarcomatoid components while sequencing analysis of both components revealed identical alterations involving TP53, PIK3CB, ARID1A, and STK11. This unique case warrants caution in designating all salivary sarcomatoid carcinomas with heterologous elements as part of the 'carcinoma ex-pleomorphic adenoma' family.

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.

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.

Current management and future challenges in salivary glands cancer

Salivary gland cancers (SGCs) are rare, accounting for less than 5% of all malignancies of the head and neck region, and are morphologically heterogeneous. The diagnosis is mainly based on histology, with the complementary aid of molecular profiling, which is helpful in recognizing some poorly differentiated, borderline, or atypical lesions. Instrumental imaging defines the diagnosis, representing a remarkable tool in the treatment plan. Ultrasound and magnetic resonance are the most common procedures used to describe the primary tumour. The treatment of SGCs is multimodal and consists of surgery, radiotherapy, and systemic therapy; each treatment plan is, however, featured on the patient and disease's characteristics. On 24 June 2022, in the meeting "Current management and future challenges in salivary gland cancers" many experts in this field discussed the state of the art of SGCs research, the future challenges and developments. After the meeting, the same pool of experts maintained close contact to keep these data further updated in the conference proceedings presented here. This review collects the insights and suggestions that emerged from the discussion during and after the meeting per se.

Secretory carcinoma of major and minor salivary glands with ETV6-NTRK3 gene fusion: overcoming misdiagnosis in the era of tumour-agnostic therapy with TRK inhibitors

Introduction

Secretory carcinoma (SC) of the salivary gland is an extraordinarily rare tumour. Accurate diagnosis of SC is crucial for understanding the clinical course, prognosis, and selection of optimal therapy. The aim of this research was to analyse retrospectively the clinical and pathological characteristics of patients diagnosed with SC of the salivary gland from 2017 onwards, which aligns with its addition to the World Health Organization classification.

Material and methods

We conducted a retrospective, single-centre, clinicopathological analysis of patients diagnosed with SC of the salivary gland between 2017 and 2022. The analysis included the evaluation of NTRK3 gene rearrangements and immunohistochemical (IHC) profiling.

Results

The study included 6 patients, comprising 4 women and 2 men. The average age of the patients was 50 years (standard deviation 26). Three cases presented with tumours in the parotid gland, while one case each involved the submandibular gland, sinonasal tract, and buccal mucosa. Interestingly, despite the characteristic IHC profile, each case was initially diagnosed as a different type of salivary gland cancer. Next-generation sequencing analysis was performed in 3 cases, revealing the presence of the ETV6-NTRK3 fusion gene. This cohort notably features an intriguing case: the youngest patient documented in literature, distinguished by extended follow-up and delayed recurrence.

Conclusions

In summary, emphasizing the risk of misdiagnosis is pivotal in the context of SC of the salivary gland, which can manifest across diverse glandular sites. Accurate diagnosis, underscored by the assessment of NTRK3 gene rearrangements, assumes a critical role in guiding effective management and treatment decisions.

Salivary Gland Secretory Carcinoma: Clinicopathologic and Genetic Characteristics of 215 Cases and Proposal for a Grading System

Salivary gland secretory carcinoma (SC), previously mammary analog SC, is a low-grade malignancy characterized by well-defined morphology and an immunohistochemical and genetic profile identical to SC of the breast. Translocation t(12;15)(p13;q25) resulting in the ETV6 :: NTRK3 gene fusion is a characteristic feature of SC along with S100 protein and mammaglobin immunopositivity. The spectrum of genetic alterations for SC continues to evolve. The aim of this retrospective study was to collect data of salivary gland SCs and to correlate their histologic, immunohistochemical, and molecular genetic data with clinical behavior and long-term follow-up. In this large retrospective study, we aimed to establish a histologic grading scheme and scoring system. A total of 215 cases of salivary gland SCs diagnosed between 1994 and 2021 were obtained from the tumor registries of the authors. Eighty cases were originally diagnosed as something other than SC, most frequently acinic cell carcinoma. Lymph node metastases were identified in 17.1% (20/117 cases with available data), with distant metastasis in 5.1% (6/117). Disease recurrence was seen in 15% (n=17/113 cases with available data). The molecular genetic profile showed ETV6 :: NTRK3 gene fusion in 95.4%, including 1 case with a dual fusion of ETV6 :: NTRK3 and MYB :: SMR3B . Less frequent fusion transcripts included ETV6 :: RET (n=12) and VIM :: RET (n=1). A 3-tiered grading scheme using 6 pathologic parameters (prevailing architecture, pleomorphism, tumor necrosis, perineural invasion (PNI), lymphovascular invasion (LVI), and mitotic count and/or Ki-67 labeling index) was applied. Grade 1 histology was observed in 44.7% (n=96), grade 2 in 41.9% (n=90), and grade 3 in 13.5% (n=29) of cases. Compared with low-grade and intermediate-grade SC, high-grade tumors were associated with a solid architecture, more prominent hyalinization, infiltrative tumor borders, nuclear pleomorphism, presence of PNI and/or LVI, and Ki-67 proliferative index >30%. High-grade transformation, a subset of grade 2 or 3 tumors, seen in 8.8% (n=19), was defined as an abrupt transformation of conventional SC into high-grade morphology, sheet-like growth, and a tumor lacking distinctive features of SC. Both overall survival and disease-free survival (5 and 10 y) were negatively affected by tumor grade, stage, and TNM status (each P <0.0001). SC is a low-grade malignancy with predominantly solid-microcystic growth patterns, driven by a gene fusion, most commonly ETV6 :: NTRK3 . There is a low risk for local recurrence and a good overall long-term survival, with a low risk for distant metastasis but a higher risk for locoregional lymph node metastasis. The presence of tumor necrosis, hyalinization, PNI and/or LVI, and positive resection margins correlate with higher tumor grade, less favorable prognosis, and increased mortality. The statistical results allowed us to design a 3-tiered grading system for salivary SC.

Two cases report of secretory carcinoma of the salivary gland in the lung: one primary and one metastatic after many years

Background

Secretory carcinoma of the salivary gland (SCSG) is a recently discovered salivary gland tumor that occurs mostly in the major salivary glands and occasionally in the skin, cervix, trachea, etc. Secretory carcinoma of the lung is extremely rare. To our knowledge, this is the third report of SCSG arising as a primary pulmonary tumor. The two SCSG cases reported in this paper are unique in that one was primary and the other was metastasized to the lung.

Case Description

Case 1 is a primary endobronchial tumor in a 66-year-old man. He went to the doctor complaining of fever, cough and yellow phlegm, and his body weight was significantly reduced by 3 kg. The bronchoscope showed the growth of new organisms in the right upper lobe of the lung. Immunohistochemistry of his biopsy specimen was positive for AE1/AE3, Keratin7 (CK7), S-100, mammaglobin, and pan-TRK, but negative for thyroid transcription factor-1 (TTF-1), napsin-A, synaptophysin (SYN), chromogranin A (CGA), and discovered on GIST-1 (Dog-1), and the MKI-67 (Ki-67) proliferation index was 2%. This case lacked the typical ETV-6 gene rearrangement. After one cycle of chemotherapy, the tumor was significantly reduced, and surgical excision was planned. Case 2 was a metastatic secretory carcinoma with a history of parotid pleomorphic adenoma resection 30 years ago and malignant pleomorphic adenoma resection 16 years ago before the study, respectively. He presented with a complaint of a parotid gland mass. Chest CT examination revealed a mass in the upper lobe of the left lung. The biopsy tissue of him exhibited a typical histological appearance under the microscope. Immunohistochemistry was positive for AE1/AE3, CK7, S-100, and mammaglobin; partially positive for estrogen receptor (ER) and pan-TRK; and negative for TTF-1, Napsin-A, SYN, CGA, P63, P40, and Dog-1. The Ki-67 proliferation index was approximately 3%. Fluorescence in situ hybridization (FISH) revealed ETV-6 gene rearrangement. After the diagnosis of SCSG, the patient underwent resection of the lung mass, and there was no recurrence of the lung after 1 month's follow-up.

Conclusions

By examining these two cases, we have a better understanding of the clinicopathological features of secretory carcinoma, which will help to improve the accuracy of pathological diagnosis.

Mutational and immunologic Landscape in malignant Salivary Gland Tumors harbor the potential for novel therapeutic strategies

Salivary gland carcinomas (SGC) are rare (3-6 % of all head and neck cancers) and show biological heterogeneity depending on the respective histological subtype. While complete surgical resection is the standard treatment for localized disease, chemotherapy or radiation therapy are frequently insufficient for the treatment of unresectable or metastasized SGC. Therefore, new therapeutic approaches such as molecularly targeted therapy or the application of immune checkpoint inhibition enhance the treatment repertoire. Accordingly, comprehensive analyses of the genomic landscape and the tumor-microenvironment (TME) are of crucial importance in order to optimize and individualize SGC treatment. This manuscript combines the current scientific knowledge of the composition of the mutational landscape and the TME in SGCs harboring the potential for novel (immune-) targeted therapeutic strategies.

Diagnostic challenges and successful organ-preserving therapy in a case of secretory carcinoma of minor salivary glands

BACKGROUND

Secretory carcinoma is a more recently described subtype of salivary gland carcinoma that may pose diagnostic challenges and frequently harbors NTRK fusions that may successfully be targeted by TRK inhibitors in advanced disease.

CASE

We present the case of a female patient with secretory carcinoma arising in the base of tongue with persistent disease after debulking surgery and definitive chemoradiation. As an alternative to salvage surgery, which would have resulted in significant impairment of swallowing and speech function, a targeted therapy with the TRK-inhibitor larotrectinib against an identified ETV6-NTRK3 fusion product was initiated. Larotrectinib treatment has been well tolerated, resulted in durable complete response and the patient maintains good swallowing and speech function.

CONCLUSION

The presented case underscores the importance of the accurate diagnosis of secretory carcinoma. It further highlights the impact of molecular testing as targeted therapies may play an important role in the management of advanced salivary gland cancers.

High-grade salivary gland carcinoma with the ETV6-NTRK3 gene fusion: A case report and literature review of secretory carcinoma with high-grade transformation

Secretory carcinoma or mammary analog secretory carcinoma is an entity of salivary gland carcinoma that is characterized by the ETV6-NTRK3 gene fusion. Although it is generally considered to be a low-grade malignancy, some cases of secretory carcinoma with high-grade transformation (SCHG) have been reported. We herein describe a case of SCHG composed almost exclusively of the high-grade component. The patient presented with a growing mass in the buccal mucosa and underwent surgery. Tumor cells showing high-grade nuclear atypia were arranged in solid or cribriform nests with comedo-like necrosis. A differential diagnosis included high-grade salivary gland carcinoma, such as salivary duct carcinoma. Immunohistochemically, tumor cells were focally positive for S-100 and negative for mammaglobin and showed nuclear positivity for pan-Trk. A reverse transcription polymerase chain reaction assay showed that the tumor harbored the ETV6-NTRK3 gene fusion. A histological review of microscopic slides of the tumor did not reveal a typical secretory carcinoma component, except for a very focal area. We ultimately diagnosed this tumor as SCHG. This case underscores the importance of recognizing the histological spectrum of SCHG and the utility of pan-Trk immunohistochemistry to detect secretory carcinoma, which may be targeted by tyrosine kinase inhibitors.

PRSS1 Upregulation Predicts Platinum Resistance in Ovarian Cancer Patients

Ovarian cancer is the most frequent cause of death among gynecologic malignancies. A total of 80% of patients who have completed platinum-based chemotherapy suffer from relapse and develop resistance within 2 years. In the present study, we obtained patients' complete platinum (cisplatin and carboplatin) medication information from The Cancer Genome Atlas database and then divided them into two categories: resistance and sensitivity. Difference analysis was performed to screen differentially expressed genes (DEgenes) related to platinum response. Subsequently, we annotated DEgenes into the protein–protein interaction network as seed nodes and analyzed them by random walk. Finally, second-ranking protease serine 1 gene (PRSS1) was selected as a candidate gene for verification analysis. PRSS1's expression pattern was continuously studied in Oncomine and cBio Cancer Genomic Portal databases, revealing the key roles of PRSS1 in ovarian cancer formation. Hereafter, we conducted in-depth explorations on PRSS1's platinum response to ovarian cancer through tissue and cytological experiments. Quantitative real-time polymerase chain reaction and Western blot assay results indicated that PRSS1 expression levels in platinum-resistant samples (tissue/cell) were significantly higher than in samples sensitive to platinum. By cell transfection assay, we observed that knockdown of PRSS1 reduced the resistance of ovarian cancer cells to cisplatin. Meanwhile, overexpression of PRSS1 increased the resistance to cisplatin. In conclusion, we identified a novel risk gene PRSS1 related to ovarian cancer platinum response and confirmed its key roles using multiple levels of low-throughput experiments, revealing a new treatment strategy based on a novel target factor for overcoming cisplatin resistance in ovarian cancer.

Expanding the Molecular Spectrum of Secretory Carcinoma of Salivary Glands With a Novel VIM-RET Fusion

BACKGROUND

Secretory carcinoma (SC), originally described as mammary analogue SC, is a predominantly low-grade salivary gland neoplasm characterized by a recurrent t(12;15)(p13;q25) translocation, resulting in ETV6-NTRK3 gene fusion. Recently, alternative ETV6-RET, ETV6-MAML3, and ETV6-MET fusions have been found in a subset of SCs lacking the classic ETV6-NTRK3 fusion transcript, but still harboring ETV6 gene rearrangements.

DESIGN

Forty-nine cases of SC revealing typical histomorphology and immunoprofile were analyzed by next-generation sequencing using the FusionPlex Solid Tumor kit (ArcherDX). All 49 cases of SC were also tested for ETV6, RET, and NTRK3 break by fluorescence in situ hybridization and for the common ETV6-NTRK3 fusions using reverse transcription polymerase chain reaction.

RESULTS

Of the 49 cases studied, 37 (76%) occurred in the parotid gland, 7 (14%) in the submandibular gland, 2 (4%) in the minor salivary glands, and 1 (2%) each in the nasal mucosa, facial skin, and thyroid gland. SCs were diagnosed more frequently in males (27/49 cases; 55%). Patients' age at diagnosis varied from 15 to 80 years, with a mean age of 49.9 years. By molecular analysis, 40 cases (82%) presented the classic ETV6-NTRK3 fusion, whereas 9 cases (18%) revealed an alternate fusion. Of the 9 cases negative for the ETV6-NTRK3 fusion, 8 cases presented with ETV6-RET fusion. In the 1 remaining case in the parotid gland, next-generation sequencing analysis identified a novel VIM-RET fusion transcript. In addition, the analysis indicated that 1 recurrent high-grade case in the submandibular gland was positive for both ETV6-NTRK3 and MYB-SMR3B fusion transcripts.

CONCLUSIONS

A novel finding in our study was the discovery of a VIM-RET fusion in 1 patient with SC of the parotid gland who could possibly benefit from RET-targeted therapy. In addition, 1 recurrent high-grade case was shown to harbor 2 different fusions, namely, ETV6-NTRK3 and MYB-SMR3B. The expanded molecular spectrum provides a novel insight into SC oncogenesis and carries important implications for molecular diagnostics, as this is the first SC-associated translocation with a non-ETV6 5' fusion partner. This finding further expands the definition of SC while carrying implications for selecting the appropriate targeted therapy.

MUTYH: Not just polyposis

MUTYH is a base excision repair enzyme, it plays a crucial role in the correction of DNA errors from guanine oxidation and may be considered a cell protective factor. In humans it is an adenine DNA glycosylase that removes adenine misincorporated in 7,8-dihydro-8-oxoguanine (8-oxoG) pairs, inducing G:C to T:A transversions. MUTYH functionally cooperates with OGG1 that eliminates 8-oxodG derived from excessive reactive oxygen species production. MUTYH mutations have been linked to MUTYH associated polyposis syndrome (MAP), an autosomal recessive disorder characterized by multiple colorectal adenomas. MAP patients show a greatly increased lifetime risk for gastrointestinal cancers. The cancer risk in mono-allelic carriers associated with one MUTYH mutant allele is controversial and it remains to be clarified whether the altered functions of this protein may have a pathophysiological involvement in other diseases besides familial gastrointestinal diseases. This review evaluates the role of MUTYH, focusing on current studies of human neoplastic and non-neoplastic diseases different to colon polyposis and colorectal cancer. This will provide novel insights into the understanding of the molecular basis underlying MUTYH-related pathogenesis. Furthermore, we describe the association between MUTYH single nucleotide polymorphisms (SNPs) and different cancer and non-cancer diseases. We address the utility to increase our knowledge regarding MUTYH in the light of recent advances in the literature with the aim of a better understanding of the potential for identifying new therapeutic targets. Considering the multiple functions and interactions of MUTYH protein, its involvement in pathologies based on oxidative stress damage could be hypothesized. Although the development of extraintestinal cancer in MUTYH heterozygotes is not completely defined, the risk for malignancies of the duodenum, ovary, and bladder is also increased as well as the onset of benign and malignant endocrine tumors. The presence of MUTYH pathogenic variants is an independent predictor of poor prognosis in sporadic gastric cancer and in salivary gland secretory carcinoma, while its inhibition has been shown to reduce the survival of pancreatic ductal adenocarcinoma cells. Furthermore, some MUTYH SNPs have been associated with lung, hepatocellular and cervical cancer risk. An additional role of MUTYH seems to contribute to the prevention of numerous other disorders with an inflammatory/degenerative basis, including neurological and ocular diseases. Finally, it is interesting to note that MUTYH could be a new therapeutic target and future studies will shed light on its specific functions in the prevention of diseases and in the improvement of the chemo-sensitivity of cancer cells.