Dutch dental hygiene students' knowledge of HPV-related oropharyngeal squamous cell carcinoma and HPV vaccination.

INTRODUCTION: The incidence of human papillomavirus (HPV)-related oropharyngeal cancer is rising, thus the understanding of HPV infection and vaccination among oral healthcare professionals is becoming increasingly important. This study aimed to investigate the knowledge of Dutch dental hygiene students on HPV infection and vaccination and assessed various aspects of HPV-related oropharyngeal cancer. METHODS: This descriptive cross-sectional study invited the entire Dutch dental hygiene student population registered in September 2016 to complete an online questionnaire concerning the knowledge of HPV infection and vaccination, including the aspects of HPV-related Oro-Pharyngeal Squamous Cell Carcinoma (OPSCC). Data were analysed using t-tests, Mann-Whitney U tests and Chi-square tests. RESULTS: Invited were all 1248 Dutch dental hygiene students and 232 (18.6%) students completed the questionnaire. More than 95% of the students indicated HPV infection as a risk factor for OPSCC and 48.7% was aware of the availability of HPV vaccination. Additionally, students considered it important to discuss HPV as a risk factor for oropharyngeal cancer with their patients. In general, the students scored highest on the questions about risk factors for OPSCC and poorest on the questions about general HPV knowledge and HPV vaccination. Although the mean overall knowledge score was significantly higher in senior compared with junior students, knowledge scores of senior students remained insufficient. CONCLUSION: This study identified deficits in knowledge of HPV and HPV vaccination among Dutch dental hygiene students. Future research should focus on improving the content of dental hygiene curricula and development of ongoing educational tools for dental hygienists.

Oral cancer prediction by noninvasive genetic screening.

Oral squamous cell carcinomas (OSCCs) develop in genetically altered epithelium in the mucosal lining, also coined as fields, which are mostly not visible but occasionally present as white oral leukoplakia (OL) lesions. We developed a noninvasive genetic assay using next-generation sequencing (NGS) on brushed cells to detect the presence of genetically altered fields, including those that are not macroscopically visible. The assay demonstrated high accuracy in OL patients when brush samples were compared with biopsies as gold standard. In a cohort of Fanconi anemia patients, detection of mutations in prospectively collected oral brushes predicted oral cancer also when visible abnormalities were absent. We further provide insight in the molecular landscape of OL with frequent changes of TP53, FAT1 and NOTCH1. NGS analysis of noninvasively collected samples offers a highly accurate method to detect genetically altered fields in the oral cavity, and predicts development of OSCC in high-risk individuals. Noninvasive genetic screening can be employed to screen high-risk populations for cancer and precancer, map the extension of OL lesions beyond what is visible, map the oral cavity for precancerous changes even when visible abnormalities are absent, test accuracy of promising imaging modalities, monitor interventions and determine genetic progression as well as the natural history of the disease in the human patient.

The role of differentiated dysplasia in the prediction of malignant transformation of oral leukoplakia.

OBJECTIVE: Oral leukoplakia is the most common oral potentially malignant disorder. Malignant transformation of oral leukoplakia occurs at an annual rate of 1%-7%. WHO-defined classic epithelial dysplasia is an important predictor of malignant transformation of oral leukoplakia, but we have previously shown in a proof of concept study that prediction improves by incorporation of an architectural pattern of dysplasia, also coined as differentiated dysplasia. We aimed to analyze this finding in a larger cohort of patients. METHOD: For this retrospective study 176 oral leukoplakia patients were included. Biopsies for all patients were assessed for the presence of dysplasia and analyzed for cytokeratin 13 and 17 expression. Moreover, the inter-observer agreement for the diagnosis of differentiated dysplasia was determined. RESULTS: In total, 33 of 176 patients developed oral squamous cell carcinoma during follow-up. Presence of classic epithelial dysplasia increased cancer risk two-fold (HR = 2.18, p = 0.026). Lesions without classic epithelial dysplasia could be further risk-stratified by the presence of differentiated dysplasia (HR = 7.36, p < 0.001). Combined classic epithelial and differentiated dysplasia imparted a seven-fold increased risk of malignant transformation (7.34, p = 0.001). Inter-observer agreement for the diagnosis of dysplasia, including differentiated dysplasia, was moderate (κ = 0.56, p < 0.001). DISCUSSION: This study emphasizes the importance of the recognition of the architectural pattern of differentiated dysplasia as a separate entity for risk prediction of malignant transformation of oral leukoplakia. Presence of any pattern of dysplasia results in accurate prediction of malignant transformation risk of oral leukoplakia.

Lactoferrin and the development of salivary stones: a pilot study.

Salivary stones (sialoliths) are calcified structures located in the ductal system of the major salivary glands. Their exact cause is not clear but in general they are characterized by concentric inorganic (hydroxyapatite) layers. The formation is a slow intermittent process which may result in enlargement of the sialolith causing obstruction of saliva secretion resulting in mealtime related pain and swelling of the affected salivary gland. Various studies reported the presence of organic material such as proteins and lipids in the core of sialoliths. In the present study the protein composition of twenty submandibular sialoliths was analyzed. It was found that proteins contributed on average 5% to the dry weight of submandibular stones whereby small salivary stones contained more extractable proteins than large salivary stones. Using a combination of SDS-PAGE gel electrophoresis and Western blotting, we identified α-amylase (in all stones; 100%), lysozyme (95%), lactoferrin (85%), secretory-IgA (75%), MUC7 (60%), complement C4 (60%) and C-reactive protein (35%). The presence, and the combinations, of lactoferrin, lysozyme, s-IgA and α-amylase in sialoliths was confirmed by ELISA. The gradually increasing size of a sialolith might provoke a local inflammatory response in the duct of the submandibular gland whereby the relatively low concentrations of lactoferrin and lysozyme may originate from neutrophils. The interaction of lactoferrin with s-IgA could contribute to the accumulation of lactoferrin in sialoliths. In summary, these results suggest a new pathophysiological role for lactoferrin, in the formation of sialoliths.

Associations between clinical and histopathological characteristics in oral leukoplakia.

OBJECTIVES: To identify possible associations between patients' demographics and habits and the clinical aspects and histopathological characteristics of oral leukoplakia (OL) at patients' first visit. METHOD: A total of 140 consecutive patients with OL at a single institute between 1997 and 2019. All biopsies were microscopically examined for classic dysplasia (CD) (WHO definition oral epithelial dysplasia) and differentiated dysplasia (DD) known from differentiated vulvar intraepithelial neoplasia. Clinical characteristics were correlated to histopathological diagnosis and odds ratios (OR) were calculated. RESULTS: A total of 96 females and 44 males, mean age 58 years, were presented. OLs were found mainly on the tongue (41%) and floor of mouth (FOM) (18%). Homogeneous OLs (58%) were associated with smoking, FOM and size <2cm and non-homogeneous OLs (42%) with non-smokers. No dysplasia was present in 40% and any dysplasia (AD) in 60%. Tongue OLs were correlated with AD (OR:6.0) and CD (OR:5.7). FOM OLs were correlated with CD (OR:4.5). DD was correlated with non-homogeneous OLs (OR:2.6). CONCLUSIONS: CD was most frequently observed in tongue and FOM OLs, while DD was associated with non-homogeneous OLs. In this series of patients, there was no consistent reliable association between the clinical and histopathological features and clinical characteristics can therefore not substitute microscopic examination of biopsies.

WEE1 kinase inhibitor MK-1775 sensitizes oral tongue squamous cell carcinoma cells to radiation irrespective of TP53 status.

OBJECTIVE: Oral tongue squamous cell carcinoma (OTSCC) frequently harbors non-functional p53 and depends on G2/M checkpoint mediated by WEE1. WEE1 suppression has been identified as a promising anti-tumor strategy. This study investigated the capacity of WEE1 kinase inhibitor (MK-1775) and its underlying mechanisms in enhancing radiation responses of OTSCC cells in vitro. MATERIALS AND METHODS: WEE1 kinase expression and its downstream target (CDK1) were investigated in OTSCC versus normal oral tissue. A synergistic combination of MK-1775 with radiation on OTSCC cell lines with different p53 statuses was assessed by viability assay. The radio-sensitizing effects of MK-1775 on apoptosis, cell cycle, DNA damage, and mitotic entry were also determined. RESULTS: Irradiation enhanced CDK1 expression in all tested cell lines, though the effect was far more pronounced in p53 mutated cell lines. MK-1775 exhibited inhibitory effects against the survival of all cell lines and enhanced their response to the radiation. These effects were strongly elicited by induction of apoptosis and lethal mitosis, but less likely by abrogation of radiation-induced G2 arrest. CONCLUSION: These results demonstrate the efficacy of MK-1775 in enhancing the radiation effect on OTSCC in vitro associated with a significant apoptotic death rate, identifying WEE1 inhibitor as a potent radiosensitizer in OTSCC irrespective of p53 mutational status.

Oral leukoplakia classification and staging system with incorporation of differentiated dysplasia.

OBJECTIVES: A classification and staging system for oral leukoplakia (OL) was introduced to promote uniform reporting. In this system, size and the histopathologic diagnosis are assessed and combined in a staging system. The various stages could be predictive for malignant transformation of OL. Differentiated dysplasia (DD) was recently recognized as an important architectural pattern of dysplasia and is highly associated with malignant transformation (MT) of OL. In the present study, DD was incorporated in the OL-system. The aim of the present study was to test the adapted system on a cohort of patients with OL. PATIENT AND METHODS: The group consisted of 140 patients. The size, absence or presence and degree of classic dysplasia (CD) and DD were incorporated into the OL-system. RESULTS: In 31/140 patients, MT occurred. Size was not statistically significant with MT (p = 0.422). The presence of dysplasia was predictive for MT (p = 0.003), whereby severe CD and DD were highly statistically significant for MT (p = 0.008). Stage IV was statistically significant for MT (p = 0.011). CONCLUSIONS: The present study emphasizes the value of the slightly modified OL-system with incorporation of DD in uniform reporting of OL and the value in predicting MT.

A narrative review of the role of Eph receptors in head and neck squamous cell carcinoma.

Tyrosine kinase receptors (TKR) coordinate a variety of pathological processes in head and neck squamous cell carcinoma (HNSCC), and eventually play a role in patient outcomes. In this review, the role of Eph receptors in HNSCC progression and the possibility of targeting these receptors are illustrated. All relevant studies were identified through a comprehensive search of four electronic databases, including PubMed, Scopus, web of science, and Embase till August 2022. EphA2 and EphB4, along with ephrin-B2, were the most extensively studied proteins in this family. However, overexpression of EphB4 and its ligand ephrin-B2 were the only proteins that consistently showed association with a poor outcome, indicating that these proteins might serve as valuable prognostic markers in HNSCC. High expression of EphA3 and EphB4 was found to play a crucial role in radioresistance of HNSCC. EphB4 loss, in particular, was observed to induce an immunosuppression phenotypic HNSCC. Currently, ongoing clinical trials are investigating the benefits of EphB4-ephrin-B2 blockade in combination with standard of care treatment in HNSCC. Further efforts are needed to explore the biological role and behavioral complexity of this family of TKR in HNSCC with great attention to avoid heterogeneity of HNSCC subsites.

The value of regular follow-up of oral leukoplakia for early detection of malignant transformation.

OBJECTIVES: Evaluate whether regular follow-up of oral leukoplakia (OL) resulted in early detection of malignant transformation (MT). METHOD: Two hundred and twenty-two consecutive patients with OL (147 females, 75 males); median follow-up period of 64 months (range: 12-300). Three groups were distinguished: group A (n = 92) follow-up at the hospital; group B (n = 84) follow-up by their dentist; group C (n = 46) lost to follow-up. RESULTS: OLs in group B compared to group A, were smaller in size (<2 cm; p < 0.001), showed more hyperkeratosis (p < 0.001) and less moderate/severe dysplasia (p < 0.001). MT occurred in 45 (20%) patients: 32 (35%) in group A, five (6%) in group B and eight (17%) in group C. There was no significant difference in clinical tumour size between group A (median: 15 mm, range: 1-40) and group B (median: 10 mm, range: 3-25; p = 0.496). Tumour size was smaller for patients in groups A and B (median: 10 mm, range 1-40) compared to group C (median: 33 mm, range: 3-100; p = 0.003). There was a positive correlation between tumour size and interval between the last visit in all patients (p = 0.022). CONCLUSION: Regular follow-up of OL resulted in early detection of MT. If properly selected, follow-up of OL performed by the dentist seems feasible.

Evaluation of head and neck cancer education at European dental schools.

AIM: In Europe, approximately 150.000 patients are diagnosed with head and neck cancer annually. Dentists play an important role in prevention and detection at an early stage when survival rates are best. This study aims to evaluate content of head and neck cancer education curricula of European dental schools. MATERIALS AND METHODS: A questionnaire, comprising 20 questions about content of curricula and teaching methods, was distributed to the deans of all 234 members of the Association for Dental Education in Europe. RESULTS: The response rate was 24%. All dental schools included head and neck cancer screening practices in their curricula, two-thirds had their students perform this screening on all patients routinely and education was mostly divided over various courses (65%). A variation in content of education in screening practices and counselling patients about various risk factors was reported. Alcohol and tobacco use were included in most curricula as risk factors for head and neck cancer (98%), gastro-oesophageal reflux was less frequently included (41%). The human papillomavirus (HPV) as a risk factor for oropharyngeal cancer was included in 94% of curricula and 87% also contained education about strategies to discuss prevention of HPV-related cancer. No association was found between curricula containing strategies about discussing HPV-related cancer and inclusion of the HPV vaccine in national immunisation programmes. CONCLUSION: Head and neck cancer teaching programmes show a considerable variation across European dental schools. Development of a unified teaching programme suitable for all European dental schools seems warranted.

Sialendoscopy increases saliva secretion and reduces xerostomia up to 60 weeks in Sjögren's syndrome patients: a randomized controlled study.

OBJECTIVE: To assess the effect of sialendoscopy of the major salivary glands on salivary flow and xerostomia in patients with Sjögren's syndrome (SS). METHODS: Forty-five patients with SS were randomly assigned to a control group (no irrigation, control, n = 15), to irrigation of the major salivary glands with saline (saline, n = 15) or to irrigation with saline followed by corticosteroid application (triamcinolone acetonide in saline, saline/TA, n = 15). Unstimulated whole saliva flow (UWSF), chewing-stimulated whole saliva flow (SWSF), citric acid-stimulated parotid flow, Clinical Oral Dryness Score (CODS), Xerostomia Inventory (XI) and EULAR SS Patient Reported Index (ESSPRI) scores were obtained 1 week before (T0), and 1, 8, 16, 24, 36, 48 and 60 weeks after sialendoscopy. Data were analysed using linear mixed models. RESULTS: Irrespective of the irrigation protocol used, sialendoscopy resulted in an increased salivary flow during follow-up up to 60 weeks. Significant between-group differences in the longitudinal course of outcomes were found for UWSF, SWSF, XI and ESSPRI scores (P = 0.028, P = 0.001, P = 0.03, P = 0.021, respectively). UWSF at 60 weeks was higher compared with T0 in the saline group (median: 0.14 vs median: 0.10, P = 0.02) and in the saline/TA group (median: 0.20, vs 0.13, P = 0.035). In the saline/TA group SWSF at 48 weeks was higher compared with T0 (median: 0.74 vs 0.38, P = 0.004). Increase in unstimulated salivary flow was also reflected in improved CODS, XI and ESSPRI scores compared with baseline. CONCLUSION: Irrigation of the major salivary glands in patients with SS increases salivary flow and reduces xerostomia.

Dental and periodontal disease in patients with inflammatory bowel disease.

OBJECTIVES: Although bowel symptoms are often predominant, inflammatory bowel disease (IBD) patients can have several oral manifestations. The aim of this study was to investigate the prevalence of dental caries and periodontal disease in patients with Crohn's disease (CD) and ulcerative colitis (UC) compared to an age and gender-matched control group of patients without IBD. MATERIAL AND METHODS: The DMFT (Decayed, Missing, Filled Teeth) scores and the DPSI (Dutch Periodontal Screening Index) of 229 IBD patients were retrieved from the electronic health record patient database axiUm at the Academic Centre for Dentistry Amsterdam (ACTA) and were compared to the DMFT scores and DPSI from age and gender-matched non-IBD patients from the same database. RESULTS: The total DMFT index was significantly higher in the IBD group compared to the control group. When CD and UC were analyzed separately, a statistically significant increased DMFT index was observed in CD patients but not in UC patients. The DPSI did not differ significantly between the IBD and non-IBD groups for each of the sextants. However, in every sextant, IBD patients were more frequently edentulous compared to the control patients. CONCLUSION: CD patients have significantly more dental health problems compared to a control group. Periodontal disease did not differ significantly between IBD and non-IBD groups as determined by the DPSI. CLINICAL RELEVANCE: It is important that IBD patients and physicians are instructed about the correlation between their disease and oral health problems. Strict oral hygiene and preventive dental care such as more frequent checkups should be emphasized by dental clinicians.

Incorporation of differentiated dysplasia improves prediction of oral leukoplakia at increased risk of malignant progression.

Oral leukoplakia is the most common oral potentially malignant disorder with a malignant transformation rate into oral squamous cell carcinoma of 1-3% annually. The presence and grade of World Health Organization defined dysplasia is an important histological marker to assess the risk for malignant transformation, but is not sufficiently accurate to personalize treatment and surveillance. Differentiated dysplasia, known from differentiated vulvar intraepithelial neoplasia, is hitherto not used in oral dysplasia grading. We hypothesized that assessing differentiated dysplasia besides World Health Organization defined (classic) dysplasia will improve risk assessment of malignant transformation of oral leukoplakia. We investigated a retrospective cohort consisting of 84 oral leukoplakia patients. Biopsies were assessed for dysplasia presence and grade, and the expression of keratins 13 (CK13) and 17, known to be dysregulated in dysplastic vulvar mucosa. In dysplastic oral lesions, differentiated dysplasia is as common as classic dysplasia. In 25 out of 84 (30%) patients, squamous cell carcinoma of the upper aerodigestive tract developed during follow-up. Considering only classic dysplasia, 11 out of 56 (20%) patients with nondysplastic lesions progressed. With the incorporation of differentiated dysplasia, only 2 out of 30 (7%) patients with nondysplastic lesions progressed. The risk of progression increased from 3.26 (Hazard ratio, p = 0.002) when only classic dysplasia is considered to 7.43 (Hazard ratio, p = 0.001) when classic and differentiated dysplasia are combined. Loss of CK13, combined with presence of dysplasia, is associated with greater risk of malignant progression (p = 0.006). This study demonstrates that differentiated dysplasia should be recognized as a separate type of dysplasia in the oral mucosa and that its distinction from classic dysplasia is of pathological and clinical significance since it is a strong (co)prognostic histopathological marker for oral malignant transformation. In oral lesions without dysplasia and retained CK13 staining the risk for progression is very low.

Global incidence and profile of ameloblastoma: A systematic review and meta-analysis.

OBJECTIVES: To evaluate the global incidence of ameloblastoma and to provide a profile of ameloblastoma patients. MATERIAL AND METHODS: A systematic review and meta-analysis was conducted. Searches were performed in PubMed, EMBASE, SCOPUS, and Web of Science for articles published from 1969 to 2018 for the global incidence and from 1995 to 2018 for the profile of ameloblastoma patients. RESULTS: Seven studies on the incidence rate of ameloblastoma were included in the meta-analysis. These studies only covered Europe, Africa, and Australia. The pooled incidence rate was 0.92 per million person-years (95% CI: 0.57-1.49), with significant heterogeneity between studies. Forty-two articles provided profile data of 6,446 ameloblastoma patients. Mean age was 34 years and the peak age incidence in the third decade of life. In Europe and North America, ameloblastoma mostly occurred at an older age when compared to Africa and South America. A slight male preference (53%) was found, and the mandible appeared to be the preferred site. The most common type of ameloblastoma was multicystic. The histopathologic patterns were mostly follicular and plexiform. CONCLUSIONS: This is the first study assessing the global incidence of ameloblastoma. The pooled incidence rate was determined to be 0.92 per million person-years.

Variation in Integrated Head and Neck Cancer Care: Impact of Patient and Hospital Characteristics.

Background: Monitoring and effectively improving oncologic integrated care requires dashboard information based on quality registrations. The dashboard includes evidence-based quality indicators (QIs) that measure quality of care. This study aimed to assess the quality of current integrated head and neck cancer care with QIs, the variation between Dutch hospitals, and the influence of patient and hospital characteristics. Methods: Previously, 39 QIs were developed with input from medical specialists, allied health professionals, and patients' perspectives. QI scores were calculated with data from 1,667 curatively treated patients in 8 hospitals. QIs with a sample size of >400 patients were included to calculate reliable QI scores. We used multilevel analysis to explain the variation. Results: Current care varied from 29% for the QI about a case manager being present to discuss the treatment plan to 100% for the QI about the availability of a treatment plan. Variation between hospitals was small for the QI about patients discussed in multidisciplinary team meetings (adherence: 95%, range 88%-98%), but large for the QI about malnutrition screening (adherence: 50%, range 2%-100%). Higher QI scores were associated with lower performance status, advanced tumor stage, and tumor in the oral cavity or oropharynx at the patient level, and with more curatively treated patients (volume) at hospital level. Conclusions: Although the quality registration was only recently launched, it already visualizes hospital variation in current care. Four determinants were found to be influential: tumor stage, performance status, tumor site, and volume. More data are needed to assure stable results for use in quality improvement.

Feedback preferences of patients, professionals and health insurers in integrated head and neck cancer care.

BACKGROUND: Audit and feedback on professional practice and health care outcomes are the most often used interventions to change behaviour of professionals and improve quality of health care. However, limited information is available regarding preferred feedback for patients, professionals and health insurers. OBJECTIVE: Investigate the (differences in) preferences of receiving feedback between stakeholders, using the Dutch Head and Neck Audit as an example. METHODS: A total of 37 patients, medical specialists, allied health professionals and health insurers were interviewed using semi-structured interviews. Questions focussed on: "Why," "On what aspects" and "How" do you prefer to receive feedback on professional practice and health care outcomes? RESULTS: All stakeholders mentioned that feedback can improve health care by creating awareness, enabling self-reflection and reflection on peers or colleagues, and by benchmarking to others. Patients prefer feedback on the actual professional practice that matches the health care received, whereas medical specialists and health insurers are interested mainly in health care outcomes. All stakeholders largely prefer a bar graph. Patients prefer a pie chart for patient-reported outcomes and experiences, while Kaplan-Meier survival curves are preferred by medical specialists. Feedback should be simple with firstly an overview, and 1-4 times a year sent by e-mail. Finally, patients and health professionals are cautious with regard to transparency of audit data. CONCLUSIONS: This exploratory study shows how feedback preferences differ between stakeholders. Therefore, tailored reports are recommended. Using this information, effects of audit and feedback can be improved by adapting the feedback format and contents to the preferences of stakeholders.

Complications of Sialendoscopy in Patients With Sjögren Syndrome.

PURPOSE: Recent literature suggests that sialendoscopy of the major salivary glands could alleviate symptoms of Sjögren syndrome (SS) and restore salivary function. The aim of this study was to evaluate the authors' experience of sialendoscopy of the salivary glands in patients with SS. MATERIALS AND METHODS: In this retrospective case series study, the surgical data of patients with SS who had undergone sialendoscopy at the VU University Medical Center (Amsterdam, The Netherlands) from November 2014 through April 2015 were used. Outcome measurements were successful entry to the salivary gland and completion of sialendoscopy as planned. Furthermore, pre- and postoperative complications were scored. Descriptive analysis of the data was performed. RESULTS: Surgical data of sialoendoscopic procedures in 26 patients with SS (24 women and 2 men; mean age, 57 yr; range, 27 to 72 yr) were analyzed. Sialendoscopy was successfully performed in 78 of 104 salivary glands (75%; 50 parotid and 28 submandibular glands) in the 26 patients. Sialendoscopy failed in 26 of the 104 sialoendoscopic procedures (25%; 2 parotid and 24 submandibular glands). In 16 salivary glands, the ductal orifice could not be identified. In 7 salivary glands, sialendoscopy could not be performed because of partial or complete stenosis of the salivary duct. In 3 salivary glands, sialendoscopy was not performed because of a ductal perforation. Three patients developed a postoperative infection. CONCLUSION: The overall rate of complications was limited and the sialoendoscopic complications in patients with SS could be regarded as minor. Most complications were seen for sialendoscopy of the submandibular glands in this specific patient category. Careful preoperative selection of patients and salivary glands could contribute to a lower rate of complications and more predictable results.

Fracture of the genial tubercles of the mandible: case report and review of the literature.

Fracture of the genial tubercles is a rare occurrence and can occur as a solitary fracture or an associated fracture of the mandible. A solitary fracture seems to be associated with severe atrophy of the mandible. A report of a case of fractured genial tubercles in an 80-year-old edentulous female patient is described and a review of the literature is presented.

Genomic Engineering of Oral Keratinocytes to Establish In Vitro Oral Potentially Malignant Disease Models as a Platform for Treatment Investigation.

Precancerous cells in the oral cavity may appear as oral potentially malignant disorders, but they may also present as dysplasia without visual manifestation in tumor-adjacent tissue. As it is currently not possible to prevent the malignant transformation of these oral precancers, new treatments are urgently awaited. Here, we generated precancer culture models using a previously established method for the generation of oral keratinocyte cultures and incorporated CRISPR/Cas9 editing. The generated cell lines were used to investigate the efficacy of a set of small molecule inhibitors. Tumor-adjacent mucosa and oral leukoplakia biopsies were cultured and genetically characterized. Mutations were introduced in CDKN2A and TP53 using CRISPR/Cas9 and combined with the ectopic activation of telomerase to generate cell lines with prolonged proliferation. The method was tested in normal oral keratinocytes and tumor-adjacent biopsies and subsequently applied to a large set of oral leukoplakia biopsies. Finally, a subset of the immortalized cell lines was used to assess the efficacy of a set of small molecule inhibitors. Culturing and genomic engineering was highly efficient for normal and tumor-adjacent oral keratinocytes, but success rates in oral leukoplakia were remarkably low. Knock-out of CDKN2A in combination with either the activation of telomerase or knock-out of TP53 seemed a prerequisite for immortalization. Prolonged culturing was accompanied by additional genetic aberrations in these cultures. The generated cell lines were more sensitive than normal keratinocytes to small molecule inhibitors of previously identified targets. In conclusion, while very effective for normal keratinocytes and tumor-adjacent biopsies, the success rate of oral leukoplakia cell culturing methods was very low. Genomic engineering enabled the prolonged culturing of OL-derived keratinocytes but was associated with acquired genetic changes. Further studies are required to assess to what extent the immortalized cultures faithfully represent characteristics of the cells in vivo.

Elucidating the Genetic Landscape of Oral Leukoplakia to Predict Malignant Transformation.

PURPOSE: Oral leukoplakia is the most common oral potentially malignant disorder with an annual malignant transformation rate of 1% to 5%. Consequently, oral leukoplakia patients have a 30% to 50% lifetime risk to develop oral squamous cell carcinoma. Although risk factors for malignant transformation of oral leukoplakia have been investigated, no definitive risk stratification model has been proposed. Next-generation sequencing can elucidate the genetic landscape of oral leukoplakia, which may be used to predict the risk for malignant transformation. EXPERIMENTAL DESIGN: We investigated a retrospective cohort of 89 oral leukoplakia patients, and analyzed their oral leukoplakia lesions for the presence of genomic copy-number alterations and mutations in genes associated with oral squamous cell carcinoma. RESULTS: In 25 of 89 (28%) patients, oral squamous cell carcinoma developed during follow-up. Seventy-nine of 89 (89%) oral leukoplakias harbored at least one genetic event. Copy-number alterations were present in 61 of 89 (69%) oral leukoplakias, most commonly gains of chromosome regions 8q24 (46%) and 20p11 (20%) and loss of 13q12 (19%). Mutations were present in 59 of 89 (66%) oral leukoplakias, most commonly in TP53 (28%), FAT1 (20%), and NOTCH1 (13%). Genetic data were combined with the presence of dysplasia to generate a prediction model, identifying three groups with a distinct risk for malignant transformation. CONCLUSIONS: We provide an extensive description of genetic alterations in oral leukoplakia and its relation to malignant transformation. On the basis of our data we provide a model for the prediction of malignant transformation of oral leukoplakia using dysplasia and genetic markers.