Simple Summary The treatment outcomes in patients with head and neck cancer vary greatly, and serious side effects are often observed. Being able to predict therapy effects is therefore crucial for choosing the best treatment option for each patient. In this study, we developed an assay to evaluate how head and neck tumor cells respond to radiation and chemotherapy. Treatment of thin patient-derived cancer tissue slices in the laboratory (in vitro) resulted in large differences in individual tumor’s reactions to treatment. In the sensitive tumors, cancer cells repaired the DNA damage inflicted by therapy only partially, stopped multiplying, and showed increased levels of cell death. On the other hand, resistant tumors were able to recover from the damage caused by the treatment. The next crucial step is to investigate whether the differences we observed in vitro can indeed predict the treatment outcomes; this is currently being tested in an ongoing clinical trial. Abstract Background: Head and neck squamous cell carcinoma (HNSCC) displays a large heterogeneity in treatment response, and consequently in patient prognosis. Despite extensive efforts, no clinically validated model is available to predict tumor response. Here we describe a functional test for predicting tumor response to radiation and chemotherapy on the level of the individual patient. Methods: Resection material of 17 primary HNSCC patients was cultured ex vivo, irradiated or cisplatin-treated, after which the effect on tumor cell vitality was analyzed several days after treatment. Results: Ionizing radiation (IR) affected tumor cell growth and viability with a clear dose-response relationship, and marked heterogeneity between tumors was observed. After a single dose of 5Gy, proliferation in IR-sensitive tumors dropped below 30% of the untreated level, while IR-resistant tumors maintained at least 60% of proliferation. IR-sensitive tumors showed on average a twofold increase in apoptosis, as well as an increased number and size of DNA damage foci after treatment. No differences in the homologous recombination (HR) proficiency between IR-sensitive and –resistant tumors were detected. Cisplatin caused a decrease in proliferation, as well as induction of apoptosis, again with marked variation between the samples. Conclusions: Our functional ex vivo assay discriminated between IR-sensitive and IR-resistant HNSCC tumors, and may also be suitable for predicting response to cisplatin. Its predictive value is currently under investigation in a prospective clinical study.

Background and Objective Thymic epithelial tumors (TETs) are a rare group of neoplasms situated in the prevascular mediastinum. Due to their rarity and histological diversity, understanding their development is quite challenging, and their molecular profile is not well defined. Although advances in molecular profiling have improved our understanding of many solid cancers, TET remains poorly characterized. The human epidermal growth factor receptor 2 (HER2/ERBB2) has gained interest as a molecular target due to its role in oncogenesis and its therapeutic significance in various malignancies; however, its potential role in treating TET remains unclear. This review examines the expression patterns, gene amplification status, and clinical implications of HER2 in thymomas and thymic carcinomas, especially in the era of antibody-drug conjugates which target tumors with low HER2 expression. Methods PubMed, Embase and Web of Science research was conducted using the terms [HER2] OR [ERBB2] OR [ErbB2] OR [HER2/neu] OR [c-erB2] AND [thymic epithelial tumors], [HER2] OR [ERBB2] OR [ErbB2] OR [HER2/neu] OR [c-erB2] AND [thymoma], and [HER2] OR [ERBB2] OR [ErbB2] OR [HER2/neu] OR [c-erB2] AND [thymic carcinoma]. There were no restrictions on publication date. After analysis, nine articles met the research criteria. Key Content and Findings In one study, thymic carcinomas expressed HER2 frequently, with focal to strong membranous positivity in 8 of the 17 cases. In another, HER2 was expressed in 58.3% of cases with other members of the receptor family and signaling pathway ligands also demonstrating frequent expression. The immunohistochemical analysis revealed that the receptors epidermal growth factor receptor (EGFR) (33.3%), phosphorylated epidermal growth factor receptor (pEGFR) (33.3%), and human epidermal growth factor receptor 3 (HER3) (45.8%), along with the ligands transforming growth factor-α (TGF-α) (54.2%), amphiregulin (25.0%), and epiregulin (91.7%), were expressed in the tumor cells. Only one case showed HER2 gene amplification. In another study, HER2 expression was positive in only one case of thymic carcinoma (1/22), whereas there was no expression observed in any of the thymoma cases (0/22). In the other series, there were scarce or no cases with HER2 expression or gene amplification. Conclusions HER2 plays a still undefined role in TET, especially in thymic carcinoma. Although gene amplification is rare, protein expression is more frequent, suggesting potential for targeted therapy. Detailed molecular profiling and innovative research methods are essential to further explore the therapeutic potential of HER2 in these rare cancers.

Simple Summary The tumor microenvironment (TME) is defined as the environment surrounding a tumor. There is a close, dynamic relation and interaction between the tumor and its neighboring microenvironment. There are some particularities of the thymus itself and of the TME of thymic epithelial tumors that hinder the routine use of targeted therapies, including immune checkpoint inhibitors. The understanding of the unique characteristics of the TME of thymic epithelial tumors could possibly result in the development of novel promising therapies. Abstract The tumor microenvironment (TME) is a complex and constantly changing entity. The TME consists of stromal cells, fibroblasts, endothelial cells, and innate and adaptive immune cells. Cancer development and progression occurs through this interplay between the tumor and the adjacent stroma. Cancer cells are capable of modifying their microenvironment by secreting various message-carrying molecules, such as cytokines, chemokines, and other factors. This action causes a reprogramming of the neighboring cells, which are enabled to play a crucial role in tumor survival and progression. The study of TME has many clinical implications in terms of cancer therapeutics because many new drugs, such as antibodies, kinase inhibitors, and liposome formulations that can encapsulate anti-cancer drugs, can be developed. Although chemotherapy is considered the standard of treatment for advanced disease, recent research has brought to light immunotherapy as a possible systemic alternative. However, the complex structure and function of the thymus hinders its routine use in clinical practice. The aim of this review paper is to discuss the recent advances in the investigation of the unique characteristics of the TME of thymic epithelial tumors that could possibly lead to the development of novel promising therapies.

Thymic epithelial tumors (TET) are a group of rare neoplasms of the anterior mediastinum comprising thymomas and thymic carcinomas. The carcinogenesis of TET is mostly unknown. Many studies, mostly retrospective case series, have tried to establish prognostic factors in TET. TET is a very heterogeneous group of tumors with many subtypes for which diagnosis and treatment remains a very challenging task. Despite the disparities among retrospective studies, there are some prognostic factors that are more pertinent such as the completeness of resection, TNM stage and the Masaoka‐Koga classification. On the other hand, the identification of different genetic pathways that result in the pathogenesis of TET represents a fascinating field of study that could possibly lead to the development of new targeted therapies. The aim of this review is to discuss the different prognostic factors and genetic markers of TET. The meticulous use of national and international databases could provide sufficient number of patients in order to draw more valid conclusions.

Lentigo maligna (LM) based on biopsy material might be lentigo maligna melanoma (LMM) after excision.

Simple Summary Oral cavity is the most common site of head and neck cancer which is ranked as the eighth most common cancer worldwide. Oral cancer treatment is often associated with significant morbidity and is sometimes ineffective. These cancers, mainly due to tobacco and alcohol consumption, can develop from oral potentially malignant disorders, the most common of which is oral leukoplakia. Some of these oral potentially malignant disorders disappear, while others will transform to oral cancer. Patients may also develop cancer in the field of cancerization. Unfortunately, except for the surgical excision of lesions with dysplasia, there is no effective intervention to effectively prevent transformation or cancer development in the field of cancerization. Moreover, no standardized biomarker has been clearly identified as sufficient to predict malignant transformation. In this article, several experts discuss the main challenges in oral cancer prevention, in particular the need (i) to define new a new classification system integrating cellular and molecular features aiming (ii) at better identifying patients at high risk of malignant transformation, and (iii) at developing treatment strategies to prevent their malignant transformation of oral potentially malignant disorders. Abstract Oral potentially malignant disorders (OPMD) may precede oral squamous cell carcinoma (OSCC). Reported rates of malignant transformation of OPMD range from 3 to 50%. While some clinical, histological, and molecular factors have been associated with a high-risk OPMD, they are, to date, insufficiently accurate for treatment decision-making. Moreover, this range highlights differences in the clinical definition of OPMD, variation in follow-up periods, and molecular and biological heterogeneity of OPMD. Finally, while treatment of OPMD may improve outcome, standard therapy has been shown to be ineffective to prevent OSCC development in patients with OPMD. In this perspective paper, several experts discuss the main challenges in oral cancer prevention, in particular the need to (i) to define an OPMD classification system by integrating new pathological and molecular characteristics, aiming (ii) to better identify OPMD at high risk of malignant transformation, and (iii) to develop treatment strategies to eradicate OPMD or prevent malignant transformation.

Simple Summary Head and neck cancer is the sixth most common cancer type worldwide, comprising tumors of the upper aero/digestive tract. Approximately 50% of these cancers originate in the oral cavity. Depending on disease stage, oral cancer patients are treated with single-modality surgery, or in combination with radiotherapy with or without chemotherapy. Despite advances in these modalities, the 5-year survival rate is merely 50%. Therefore, implementation of targeted therapies, directed against signaling molecules, has gained attention. One potential target is the MET protein, which can be present on the surface of cancer cells, orchestrating aggressive behavior. As cancer cells can shed the extracellular part of MET from their surface, it is important to identify for MET positive patients whether they possess the entire and/or only the intracellular part of the receptor to assess whether targeted therapies directed against the extracellular, intracellular, or both parts of MET need to be implemented. Abstract The receptor tyrosine kinase MET has gained attention as a therapeutic target. Although MET immunoreactivity is associated with progressive disease, use of targeted therapies has not yet led to major survival benefits. A possible explanation is the lack of companion diagnostics (CDx) that account for proteolytic processing. During presenilin-regulated intramembrane proteolysis, MET’s ectodomain is shed into the extracellular space, which is followed by γ-secretase-mediated cleavage of the residual membranous C-terminal fragment. The resulting intracellular fragment is degraded by the proteasome, leading to downregulation of MET signaling. Conversely, a membrane-bound MET fragment lacking the ectodomain (MET-EC-) can confer malignant potential. Use of C- and N-terminal MET monoclonal antibodies (moAbs) has illustrated that MET-EC- occurs in transmembranous C-terminal MET-positive oral squamous cell carcinoma (OSCC). Here, we propose that ectodomain shedding, resulting from G-protein-coupled receptor transactivation of epidermal growth factor receptor signaling, and/or overexpression of ADAM10/17 and/or MET, stabilizes and possibly activates MET-EC- in OSCC. As MET-EC- is associated with poor prognosis in OSCC, it potentially has impact on the use of targeted therapies. Therefore, MET-EC- should be incorporated in the design of CDx to improve patient stratification and ultimately prolong survival. Hence, MET-EC- requires further investigation seen its oncogenic and predictive properties.

OBJECTIVE Patients with cutaneous melanoma and a positive sentinel node (SN) are currently eligible for adjuvant treatment with targeted therapy and immune checkpoint inhibitors. Near-infrared (NIR) fluorescence imaging could be an alternative and less invasive tool for SN biopsy to select patients for adjuvant treatment. One potential target for NIR is the mesenchymal-epithelial transition factor (MET). This study aimed to assess MET immunoreactivity in positive SNs and to evaluate its potential diagnostic, prognostic and therapeutic value. METHODS In this retrospective study, positive SN samples from patients with primary cutaneous melanoma were collected to assess MET immunoreactivity. To this end, paraffin-embedded SNs were stained for MET (monoclonal antibody D1C2). A 4-point Histoscore was used to determine cytoplasmic and membranous immunoreactivity (0 negative/1 weak/2 moderate/3 strong). Samples were considered positive when ≥10% of the cancer cells showed MET expression (staining intensity ≥1). Patient and clinicopathological characteristics were used for descriptive statistics, binary logistic regression, and survival analyses. RESULTS Positive MET immunohistochemistry was observed in 24 out of 37 samples (65%). No statistically significant associations were found between MET positivity and the following prognostic factors: Breslow thickness (P = 0.961), ulceration (P = 1.000), and SN tumor burden (P = 0.792). According to MET positivity, Kaplan-Meier curves showed no significant differences in survival. CONCLUSION This exploratory study found no evidence to support MET immunoreactivity in positive SNs as a possible diagnostic or prognostic indicator in patients with melanoma.

A clear margin is an important prognostic factor for most solid tumours treated by surgery. Intraoperative fluorescence imaging using exogenous tumour-specific fluorescent agents has shown particular benefit in improving complete resection of tumour tissue. However, signal processing for fluorescence imaging is complex, and fluorescence signal intensity does not always perfectly correlate with tumour location. Raman spectroscopy has the capacity to accurately differentiate between malignant and healthy tissue based on their molecular composition. In Raman spectroscopy, specificity is uniquely high, but signal intensity is weak and Raman measurements are mainly performed in a point-wise manner on microscopic tissue volumes, making whole-field assessment temporally unfeasible. In this review, we describe the state-of-the-art of both optical techniques, paying special attention to the combined intraoperative application of fluorescence imaging and Raman spectroscopy in current clinical research. We demonstrate how these techniques are complementary and address the technical challenges that have traditionally led them to be considered mutually exclusive for clinical implementation. Finally, we present a novel strategy that exploits the optimal characteristics of both modalities to facilitate resection with clear surgical margins.

INTRODUCTION A challenge in the treatment of patients with head and neck cancer is the management of occult cervical lymph node (LN) metastases. Single-fiber reflectance (SFR) spectroscopy has the potential to detect physiological tissue changes that occur in a positive LN. This pilot study aimed to investigate whether SFR spectroscopy could serve as an alternative or additional technique to detect cervical lymph node metastases. MATERIALS AND METHODS We performed intraoperative SFR spectroscopy measurements of LNs with and without malignancies. We analyzed if physiological and scattering parameters were significantly altered in positive LNs. RESULTS Nine patients with a total of nineteen LNs were included. Three parameters, blood volume fraction (BVF), microvascular saturation (StO2), and Rayleigh amplitude, were significantly lower in positive LNs. They were combined into one optical parameter 'delta', using discriminant analysis. Delta was significantly decreased in positive LNs, p = 0,0006. It had a high diagnostic accuracy where the sensitivity, specificity, PPV, and NPV were 90,0%, 88.9%, 90,0%, and 88.9%, respectively. The area under the ROC curve was 96.7% (95% confidence interval 89.7-100.0%). CONCLUSION This proof of principle study is a first step in the development of an SFR spectroscopy technique to detect LN metastases in real time. A next step towards this goal is replicating these results in LNs with smaller metastases and in a larger cohort of patients. This future study will combine SFR spectroscopy with fine-needle aspiration, using the same needle, to perform preoperative in vivo measurements.

This study reports on the effects of insertion velocity, needle tip geometry and needle diameter on tissue deformation and maximum insertion force. Moreover, the effect of multiple insertions with the same needle on the maximum insertion force is reported. The tissue deformation and maximum insertion force strongly depend on the insertion velocity and the tip geometry. No correlation was found between the outer diameter and the maximum insertion force for small needles (30G - 32G). The endurance experiments showed no remarkable difference in the maximum insertion force during 100 insertions.

Background In head and neck oncological surgery the goal is to achieve a complete tumor resection with acceptable remaining function and appearance. For oral cavity squamous cell carcinoma (OCSCC) only 15% of the resections are reported as adequate. Since 2013, we have performed intraoperative assessment of resection margins (IOARM) in our institute, based on palpation and visual inspection of the resected specimens by pathologist and surgeon. This has resulted in an improvement of adequate resection margins from 15% to 50%, underlining the importance of IOARM. However, this method is subjective, labor intensive, and logistically challenging. Objective Our aim is to develop an objective method for fast and reliable IOARM based on Raman spectroscopy (RS). Methods RS is a non-destructive objective optical technique that provides information about the molecular composition of tissues. It can discriminate between healthy tissue and tumors. We developed a prototype Raman instrument employing a fiber-optic needle probe. The fiber-optic needle is driven into the OCSCC specimen, from the resection surface towards the tumor. Based on the Raman spectra collected along the insertion path, the location of the tumor border can be determined. From this the resection margin can be determined. Results First tests of the method show that the instrument accurately predicts the achieved resection margins. Per location the measurement and assessment takes 5 seconds. Conclusions This development signifies an important step towards a fast and objective IOARM. The fast measurement time enables an objective inspection of the margins achieved at a large number of locations of the resection surface.