Expression patterns of cancer stem cell markers ALDH1 and CD133 correlate with a high risk of malignant transformation of oral leukoplakia

Molecular markers for predicting oral cancer development in premalignant oral leukoplakia (OL) are urgently needed. The objective of this study was to examine the expression patterns of cancer stem cell markers ALDH1 and CD133 in samples from patients with OL, and determine their prognostic values for subsequent development of oral cancer. Immunohistochemistry for ALDH1 and CD133 was performed in samples from a cohort of 141 patients with biopsy‐proven OL who received a mean follow‐up of 5.5 years. Patient clinicopathologic and follow‐up data were analyzed. Expression of ALDH1 and CD133 was observed in 54 (38.3%) and 32 (22.7%) of 141 patients with OL, respectively. Kaplan–Meier analysis showed that 48.1% patients with ALDH1‐positivity developed oral cancer compared with 12.6% those with ALDH1‐negativity (p < 0.001). Meanwhile, 59.4% patients with CD133‐positivity developed oral cancer compared with 16.5% those with CD133‐negativity (p < 0.001). Multivariate analysis revealed that ALDH1 and CD133 expression was associated with 4.17‐fold [95% confidence interval (CI), 1.96–8.90; p < 0.001] and 2.86‐fold (95% CI, 1.48‐5.55; p = 0.002) increased risk of OL transformation, respectively. Collectively, these data demonstrated for the first time that the expression of ALDH1 and CD133 correlated with malignant transformation in a large series of patients with OL who received a long‐term follow‐up, which suggests that they may serve as predictors to identify OL with a high risk of oral cancer development.     

Field cancerisation of the oral cavity: Comparison of the spectrum of molecular alterations in cases presenting with both dysplastic and malignant lesions

Dysplastic lesions and invasive oral squamous cell carcinoma (SCC) from patients with field change were screened by restriction fragment length polymorphism (RFLP) and microsatellite assay. All tumours contained more genetic changes than the matched dysplasia which are likely to represent progression. Four of the 15 dysplastic lesions harboured the same abnormalities detected in the tumour and some paired lesions showed identical novel microsatellite alleles. The finding of identical ‘genetic fingerprints’ in dysplastic lesions and invasive carcinoma from the same patient provides strong evidence that these dysplasias are precursor lesions and that multiple lesions have probably arisen due to transfer of the progeny of an altered cell. Eight of the 15 dysplastic lesions showed alterations which were not present in the matched cancer, showing that evolution of subclones, or fusion of multiple clones also occurs. A further case showed loss of different alleles in the paired samples. These findings highlight the complexity of the genetic abnormalities present in the mucosa of patients with field change and suggests that the origin of these altered foci may be diverse.     

High Prevalence of Human Papillomavirus Type 18 in Oral Potentially Malignant Disorders in Thailand

Objectives: The main objectives of this study were to investigate the detection rate of high-risk human papillomavirus types 16 and 18 (high-risk HPV16/18) in oral potentially malignant disorders (OPMDs) including oral leukoplakia (OL) and oral lichen planus (OLP) in a Thai population and their associations with demographic, risk habits, and clinicopathologic features. Methods: Paraffin-embedded formalin-fixed specimens from 101 OL and 59 OLP patients with patients’ demographic, risk habits, and clinicopathologic data were collected. Conventional qualitative polymerase chain reaction was used to detect high-risk HPV16/18 DNA. Associations between high-risk HPV type 16/18 and demographic, clinicopathologic, risk factors (tobacco and alcohol uses) of OPMDs were analysed by Chi-square or Fisher’s exact test. The results with p value less than 0.05 were considered statistically significant. Results: HPV16/18 DNA was found in both OL and OLP groups with the detection rate of 19.8% and 18.6%, respectively. Approximately 90% of high-risk HPV were HPV18 subtype. Additionally, in OL group, high-risk HPV was found more frequently in patients with moderate/severe dysplasia than that in mild dysplasia. Interestingly, in OLP group, high-risk HPV was only detected in atrophic/ulcerative subtypes. None of risk factors was associated with high-risk HPV. Conclusions: Approximately 19% of OPMDs were HPV16/18-positive. HPV18 DNA was predominantly detected in both OL and OLP patients (90%). Additionally, the detection rate of high-risk HPV was higher in more severe dysplastic cases of OL and more clinically severe cases of OLP.     

Management for premalignant lesions of the oral cavity

Premalignant lesions of the oral cavity present as visibly abnormal areas of mucosa and may be a source of significant anxiety for the patient and the clinician. Suspicious lesions should be biopsied to evaluate for dysplasia. The risk of malignant transformation may relate to patient characteristics, environmental risk factors and genetic alterations. Management of such lesions hinges on risk modification, surveillance, symptom management and directed biopsies. Excision or ablation of dysplastic lesions is indicated. We review the current evidence relating to management of premalignant lesions of the oral mucosa and make recommendations for practice patterns.     

Bladder cancer,a two phased disease?

The processes of intraepithelial migration, intraluminal seeding, and field cancerization as models for initiation, spread, and recurrences of urothelial cell carcinoma (UCC) are reviewed in light of recent molecular investigations. The accumulated molecular data on synchronous and metachronous tumors indicate that the majority of recurrent and multiple tumors are monoclonal. Molecular data has also shown the presence of chromosomal and genetic changes in precursor lesions as well as in normal urothelial cells. Genetic-histological mapping of cystectomized bladders has shown that overt tumors occur as local events in areas of genetically altered urothelium. A model is put forward in which the tumor process is initiated by genetically altered but histologically normal cells that produce fields of altered cells by intraepithelial displacement. By the accumulation of further genetic changes the fields of altered urothelium reaches a state of criticality, which locally may produce frank tumors.     

Two stem cell markers, ATP-binding cassette, G2 subfamily (ABCG2) and BMI-1, predict the transformation of oral leukoplakia to cancer: a long-term follow-up study

BACKGROUND:

Although oral leukoplakia (OL) is the best‐known potentially malignant disorder, the risk of OL malignant transformation is difficult to assess. ATP‐binding cassette, G2 subfamily (ABCG2) and BMI‐1 are stem cell markers that have been found to be associated with head and neck tumorigenesis. The objective of the current study was to evaluate the usefulness of ABCG2 and BMI‐1 in predicting OL transformation.

METHODS:

In a retrospective cohort of 135 patients with OL from the study institution who had a mean follow‐up of 5.5 years, 32 developed cancer between 1985 and 2008. The expression of ABCG2 and BMI‐1 was determined using immunohistochemistry in samples from these patients, and included untransformed OL (n = 103) and malignant‐transformed OL (n = 32). The association between protein expression and clinicopathological parameters and transformation was analyzed.

RESULTS:

Expression of ABCG2 and BMI‐1 was observed in 58 (43.0%) and 44 (32.6%) of 135 patients, respectively. The correlation between ABCG2 and BMI‐1 expression was significant (P = .024). Kaplan‐Meier analysis revealed that 37.9% of patients with ABCG2 positivity developed cancer compared with 13.0% of patients with ABCG2 negativity (P = .014, log‐rank test). Approximately 40.9% of patients with BMI‐1 positivity developed cancer compared with 15.4% of patients with BMI‐1 negativity (P = .029, log‐rank test). Multivariate analysis revealed that ABCG2 and BMI‐1 expression was associated with a 3.24‐fold (95% confidence interval [95% CI], 1.31‐7.98; P = .011) and 4.03‐fold (95% CI, 1.59‐10.26; P = .003) increased the risk of transformation, respectively.

CONCLUSIONS:

ABCG2 and BMI‐1 expression was found to be associated with the development of oral cancer in a large cohort of patients with OL for whom long‐term follow‐up was available, which suggests that ABCG2 and BMI‐1 may be used as predictors of OL transformation. Cancer 2011;. © 2011 American Cancer Society.     

Human papillomavirus infection and premalignant lesions of the oral cavity: A cross-sectional study in Allahabad, North India

Aim:   To assess the role of human papillomavirus (HPV) in premalignant lesions of the oral cavity using the second-generation Hybrid Capture assay kit (Digene Corporation) and to study the correlation between this technique and morphological changes (koilocytosis) on histopathology in those lesions.
Methods:   A hospital-based cross-sectional study was undertaken including 92 patients with premalignant lesions of the oral cavity (the study group) and a control group of 35 patients with no oral disease. All the participants were interviewed regarding possible risk factors. Oral exfoliated cells in the saliva were tested for HPV DNA using an HPV RNA probe of 13 high-risk HPV genotypes (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and 68). Simultaneously biopsy specimens of the lesions were examined under a light microscope for evidence of koilocytosis, an empirical marker for HPV infection. Pearson's χ² test using SPSS V.16 was applied for statistical analysis.
Results:   HPV DNA was detected in 44.6% of the study group (41 out of 92), and 14.3% of the controls (five out of 35). The association was independent of the influence of betel quid and tobacco chewing, two established causal factors for oral pre-cancers. Out of the total 92 participants in the study group there was evidence of koilocytosis on the histological sections of 42 individuals (45.6%).
Conclusion:   The results support a strong association between HPV infection and oral premalignant lesions, particularly oral lichen planus and squamous papilloma. Koilocytosis on histology is a good predictor of HPV infection.     

Combined effects of human papillomavirus-18 and n-methyl-n-nitro-n-nitrosoguanidine on the transformation of normal human oral keratinocytes

We immortalized oral keratinocytes by transfecting them with recombinant human papillomavirus (HPV) type 18 DNA and established three cell lines. These lines were morphologically different from their normal counterpart, contained integrated entire HPV-18 DNA, and expressed the viral E6/E7 genes. The cells contained less p53 protein and more c-myc mRNA than normal cells. However, they proliferated only in keratinocyte growth medium (KGM) containing low calcium and were not tumorigenic in nude mice. To test the hypothesis that tumors result from the combined effect of a “high-risk” HPV and chemical carcinogens in the human oral cavity, we exposed the immortalized cells to the chemical carcinogen N-methyl-N′-nitro-N-nitrosoguanidine. Three chemically transformed cell colonies were isolated. These cells (a) proliferated well in both KGM and Dulbecco′s modified minimum essential medium containing physiological levels of calcium; (b) were capable of proliferating in nude mice; (c) contained intact, integrated HPV-18 sequences; (d) transcribed substantially more HPV-18 E6/E7, transforming growth factor-α, and c-myc than the immortalized counterpart; and (e) contained, like the immortalized counterpart, less wild-type p53 protein and DCC message. These data indicate that human oral keratinocytes can be transformed by sequential exposure of normal keratinocytes to a “high-risk” HPV and chemical carcinogens. © 1994 Wiley-Liss, Inc.     

Evaluation of TGF-alpha and EGFR expression in oral leukoplakia and oral submucous fibrosis by quantitative immunohistochemistry.

OBJECTIVE: Oral leukoplakia (OL) and oral submucous fibrosis (OSMF) are clinically distinct preneoplastic states that precede the development of oral squamous cell carcinoma. Recently, attempts are being made to identify specific molecular event(s) as prognostic markers to identify oral precancerous lesions with higher malignant potential. The goal of the present study was to evaluate the expression of EGFR and its ligand TGF-alpha in OL with dysplasia and OSMF as intermediate markers of malignancy by quantitative immunohistochemistry. METHODS: Oral tissues were stained with monoclonal antibodies to TGF-alpha and EGFR. The results were analyzed with Photoquant image analysis software. RESULTS: The expression of TGF-alpha and EGFR was upregulated in OL, OSMF and oral squamous cell carcinomas relative to normal oral mucosa. The area and intensity of staining of TGF-alpha in the proliferative layers (stratum germinativum) increased linearly in OL with mild, moderate and severe dysplasia as compared to control mucosa (p < 0.05). EGFR levels increased linearly in the stratum spinosum in OL with increasing degrees of dysplasia (p < 0.05). In general, the expression of both proteins in OSMF was similar to that in OL with moderate dysplasia. CONCLUSIONS: EGFR and TGF-alpha represent early markers of malignancy in OL with dysplasia. Quantitative measurement of these proteins may provide intermediate endpoints in prospective chemopreventive trials.     

Dental Calculus as a Potential Biosource for Human Papillomavirus Detection in Oral Squamous Cell Carcinoma

Objective: The infection of human papillomaviruses (HPVs) plays a role in the development of oral squamous cell carcinoma (OSCC). A poor oral hygiene and dental calculus may cause the infection to persist. Therefore, this study aimed to assess whether this dental calculus could serve as a potential biosource in early detection of HPVs in patients with OSCC. Methods: DNA was isolated from the dental calculus of people diagnosed with OSCC, and MY09/11 primer set was used to detect the presence of HPV. The positive samples were further sequenced and aligned using megablast NCBI BLAST tool to identify the HPV genotype. Results: Electrophoresis examination showed that 4 of 14 samples collected (29%) had a clear single band, of which three had 97% to 99% similarity to a high-risk genotype HPV-58. Meanwhile, the other sample had 99% similarity to an unclassified papillomaviridae. Conclusion: Dental calculus is a promising source of HPV in oral cavity and could be used as a biomarker for early detection.     

A low incidence of p53 mutations in pre-malignant lesions of the oral cavity from non-tobacco users

To determine the incidence of pS3 mutations in pre-malignant lesions of the oral cavity from individuals without prior history of tobacco use, we have analyzed the conserved regions of the pS3 gene (exons 5-9) in archival oral cavity lesion specimens obtained from patients with varied tobacco use histories, by polymerase chain reaction/single strand conformational polymorphism (PCR/SSCP) and DNA sequencing analysis. Twenty-six lesions were analyzed from 14 patients, with multiple lesions obtained from 8 patients. Six of these patients used tobacco, (3 being cigarette smokers, 1 ex-cigarette smoker, 1 moderate cigar smoker and 1 snuff chewer). The remaining 8 patients had no prior history of tobacco use. Thirteen of the pre-malignant lesions exhibited severe dysplasia, 9 exhibited moderate dysplasia and 4 exhibited mild dysplasia. Four of the 26 lesions exhibited pS3 mutations, each being from a tobacco user. None of the 13 lesions from never-tobacco users exhibited pS3 mutations. There was a significantly higher p53 mutation incidence in pre-malignant lesions from tobacco users (including ex-smokers) than in non-tobacco users as well as in cigarette smokers plus snuff chewers than in non-tobacco users. Two of the mutations were observed in lesions exhibiting severe dysplasia: I in a lesion exhibiting moderate dysplasia and I in a lesion exhibiting mild dysplasia. These data suggest that pS3 mutation may be a very early event in oral cavity tumor progression and demonstrate that pre-malignant lesions obtained from non-tobacco users do not exhibit pS3 mutations.     

The precancer risk of betel quid chewing,tobacco use and alcohol consumption in oral leukoplakia and oral submucous fibrosis in southern Taiwan

In areas where the practise of betel quid chewing is widespread and the chewers also often smoke and drink alcohol, the relation between oral precancerous lesion and condition to the three habits is probably complex. To explore such association and their attributable effect on oral leukoplakia (OL) and oral submucous fibrosis (OSF), a gender-age-matched case-control study was conducted at Kaohsiung, southern Taiwan. This study included 219 patients with newly diagnosed and histologically confirmed OL or OSF, and 876 randomly selected community controls. All information was collected by a structured questionnaire through in-person interviews. A preponderance of younger patients had OSF, while a predominance of older patients had OL. Betel quid chewing was strongly associated with both these oral diseases, the attributable fraction of OL being 73.2% and of OSF 85.4%. While the heterogeneity in risk for areca nut chewing across the two diseases was not apparent, betel quid chewing patients with OSF experienced a higher risk at each exposure level of chewing duration, quantity and cumulative measure than those who had OL. Alcohol intake did not appear to be a risk factor. However, cigarette smoking had a significant contribution to the risk of OL, and modified the effect of chewing based on an additive interaction model. For the two oral premalignant diseases combined, 86.5% was attributable to chewing and smoking. Our results suggested that, although betel quid chewing was a major cause for both OL and OSF, its effect might be difference between the two diseases. Cigarette smoking has a modifying effect in the development of oral leukoplakia.     

STAT1 inhibits T-cell exhaustion and myeloid derived suppressor cell accumulation to promote antitumor immune responses in head and neck squamous cell carcinoma

Cancers of the oral cavity remain the sixth most diagnosed cancer worldwide, with high rates of recurrence and mortality. We determined the role of STAT1 during oral carcinogenesis using two orthotopic models in mice genetically deficient for Stat1. Metastatic (LY2) and nonmetastatic (B4B8) head and neck squamous cell carcinoma (HNSCC) cell lines were injected into the oral cavity of Stat1 deficient (Stat1^−/−) and Stat1 competent (Stat1^+/+) mice. Stat1^−/− mice displayed increased tumor growth and metastasis compared to Stat1^+/+ mice. Mechanistically, Stat1^−/− mice displayed impaired CD4+ and CD8+ T-cell expansion compared to Stat1^+/+ mice. This was associated with enhanced T-cell exhaustion, and severely attenuated T-cell antitumor effector responses including reduced expression of IFN-γ and perforin at the tumor site. Interestingly, tumor necrosis factor (TNF)-α production by T cells in tumor-bearing mice was suppressed by Stat1 deficiency. This deficiency in T-cell expansion and functional responses in mice was linked to PD-1 and CD69 overexpression in T cells of Stat1^−/− mice. In contrast, we observed increased accumulation of CD11b+ Ly6G+ myeloid derived suppressor cells in tumors, draining lymph nodes, spleens and bone marrow of tumor-bearing Stat1^−/− mice, resulting in a protumorigenic microenvironment. Our data demonstrates that STAT1 is an essential mediator of the antitumor response through inhibition of myeloid derived suppressor cell accumulation and promotion of T-cell mediated immune responses in murine head and neck squamous cell carcinoma. Selective induction of STAT1 phosphorylation in HNSCC patients could potentially improve oral tumor outcomes and response to therapy.     

HPV DNA and survivin expression in epithelial oral carcinogenesis: a relationship?

HPV has been thought to be involved in the development of several oral diseases, such as premalignant mucosal lesions and oral carcinoma. Survivin is a recently characterized IAP protein, which is abundantly expressed in most solid and haematological malignancies, but undetectable in normal adult tissues. Aim of this study was to investigate survivin expression and HPV presence in oral premalignant lesions and oral carcinoma. 47 samples of oral tissue including 11 squamous cell carcinomas (OSCC), 16 oral leukoplakias (OL) and 20 normal oral mucosa specimens, after investigation of HPV presence by nested PCR (consensus MY/GP primers) and viral genotype identification by direct sequencing were investigated by immunohistochemistry to detect survivin expression. Survivin expression was evident in 4/7 (57.1%) HPV+ and 4/4 (100%) HPV- OSCC, 6/7 (85.7%) HPV+ and 5/9 (55.5%) HPV- OL and in 0/20 (0%) control samples. Data showed high levels of survivin expression in HPV-positive SCCs, even if mean values were lower than HPV-negative ones, which in particular showed survivin expression in 100% of cases. Conversely, survivin expression was greater in HPV+ precancerous lesions than in HPV- ones. Our findings suggest that survivin may be involved in HPV- mediated deregulation during maturation of squamous epithelium through modulation of the apoptotic processes and, conversely, HPV may have a direct or indirect effect on the regulation of the survivin expression level. In particular, the results of this study suggest distinguishing between cancerous and precancerous oral lesions with respect to survivin expression when HPV infection is present. The most unfavourable behaviour is likely to be for the HPV- OSCC.     

Is age a risk factor for Candida glabrata colonisation?

Studies have reported that Candida glabrata infections are more common in older adults. We sought to determine colonisation rates of C. glabrata in the oral cavity and its relationship with age, comorbid illnesses and hospital or extended care facility stay. Samples were obtained from four sites in the oral cavity and from dentures, when available, from 408 subjects from the community (136), hospital (126) or an extended care facility (146). Overall, 219 (53.7%) subjects were colonised with yeast; the predominant species was Candida albicans. Sixty‐two patients (15.2%) were colonised with C. glabrata. None of the subjects <40 years was colonised with C. glabrata; in those from the community, only nine persons, all of whom were >60 years, were colonised with C. glabrata. By multivariate analysis, increasing age, dentures and use of psychotropic medications were independently associated with C. glabrata colonisation; residing in the community, rather than hospital or extended care, was strongly protective against colonisation. Candida glabrata colonisation is multifactorial; age, and hospitalisation/extended care stay contribute to colonisation. Dentures are strongly associated with colonisation with any yeast and with C. glabrata. Further study is needed to evaluate the relationship of these findings to increasing C. glabrata infections in older adults.     

Human papillomavirus types 16 and 18 in epithelial dysplasia of oral cavity and oropharynx: a meta-analysis, 1985-2010

Human papillomavirus (HPV) types 16 and 18 are causally related to a sub-set of oral cavity and oropharyngeal squamous cell cancers. However, a clear estimate of the prevalence of HPV-16/18 in oral cavity and oropharyngeal dysplasia (OOPD) is not available. This literature review and meta-analysis was conducted to provide a prevalence estimate for HPV-16/18 in OOPD. Twenty-two studies that reported prevalence of HPV-16 and/or 18 in 458 OOPD lesions were analyzed. Meta-analysis was used to evaluate the prevalence of HPV-16/18 and logistic regression was used for stratified analysis by age, gender, and histological grade. The overall prevalence of HPV-16/18 in OOPD lesions was 24.5% [95% confidence interval (CI), 16.4–36.7%)]. The individual prevalence for HPV-16 alone was 24.4%. The prevalence of HPV-16/18 in oral cavity lesions alone was 25.3% (95% CI, 14.2–45.2%). The odds of detection of HPV-16/18 in dysplastic lesions in males were twice that of females [odds ratio (OR), 2.44]. HPV-16/18 were 3 times more common in dysplastic lesions (OR, 3.29; 95% CI, 1.95–5.53%) and invasive cancers (OR, 3.43; 95% CI, 2.07–5.69%), when compared to normal biopsies. There was no significant difference in HPV-16/18 rates between dysplastic lesions and cancers or between mild, moderate or severe dysplastic lesions. This meta-analysis provides a quantification of the prevalence of HPV types 16/18 in OOPD lesions. These results also support the assumption that HPV-16/18 infection occurs during the early phase of the oral cavity and oropharyngeal carcinogenesis.     

Risk factors for multiple oral premalignant lesions

Oral leukoplakia, oral submucous fibrosis and erythroplakia are 3 major types of oral premalignant lesions. Multiple oral premalignant lesions may possibly develop due to field cancerization, where carcinogenic exposures can cause simultaneous genetic defects to the upper aerodigestive tract epithelium, putting the epithelium at high risk for development of premalignant lesions at different stages of carcinogenesis. There have been no epidemiological studies on risk or protective factors of the disease. A case-control study was conducted with data from the baseline screening of a randomized oral cancer screening trial in Kerala, India. A total of 115 subjects with multiple oral premalignant lesions (8-10% of oral premalignant lesions in our case series) were included: 64 subjects with oral leukoplakia and oral submucous fibrosis, 19 subjects with oral leukoplakia and erythroplakia, 22 subjects with oral submucous fibrosis and erythroplakia and 10 subjects with all 3 lesions. Individuals without oral lesions were considered controls (n=47,773). The odds ratio (OR) for ever tobacco chewers was 37.8 (95% confidence interval (CI)=16.2-88.1) when adjusted for age, sex, education, BMI, smoking, drinking and fruit/vegetable intake. Dose-response relationships were seen for the frequency (p<0.0001) and duration of tobacco chewing (p<0.0001) with the risk of multiple oral premalignant lesions. Whereas alcohol drinking may possibly be a risk factor for multiple oral premalignant lesions, smoking was not associated with the risk of multiple oral premalignant lesions (OR=0.9, 95%CI=0.5-1.7). The results suggest that tobacco chewing was the most important risk factor for multiple oral premalignant lesions and may be a major source of field cancerization on the oral epithelium in the Indian population.     

Periodontal pathogens are a risk factor of oral cavity squamous cell carcinoma,independent of tobacco and alcohol and human papillomavirus

Over the past decade, there has been a change in the epidemiology of oral cavity squamous cell cancer (OC-SCC). Many new cases of OC-SCC lack the recognized risk factors of smoking, alcohol and human papilloma virus. The aim of this study was to determine if the oral microbiome may be associated with OC-SCC in nonsmoking HPV negative patients. We compared the oral microbiome of HPV-negative nonsmoker OC-SCC(n = 18), premalignant lesions(PML) (n = 8) and normal control patients (n = 12). Their oral microbiome was sampled by oral wash and defined by 16S rRNA gene sequencing. We report that the periodontal pathogens Fusobacterium, Prevotella, Alloprevotella were enriched while commensal Streptococcus depleted in OC-SCC. Based on the four genera plus a marker genus Veillonella for PML, we classified the oral microbiome into two types. Gene/pathway analysis revealed a progressive increase of genes encoding HSP90 and ligands for TLRs 1, 2 and 4 along the controls→PML → OC-SCC progression sequence. Our findings suggest an association between periodontal pathogens and OC-SCC in non smoking HPV negative patients.     

Assessing the causal association between 25‐hydroxyvitamin D and the risk of oral and oropharyngeal cancer using Mendelian randomization

Circulating 25‐hydroxyvitamin D (25OHD) is an appealing potential intervention for cancer risk and has been associated with oral and oropharyngeal cancer risk but evidence is inconsistent. The availability of genetic variants, uncorrelated with known confounders, but predictive of 25OHD and genetic data in a large oral and oropharyngeal cancer collaboration aids causal inference when assessing this association. A total of 5,133 oral and oropharyngeal cancer cases and 5,984 controls with genetic data were included in the study. Participants were based in Europe, North America and South America and were part of the Genetic Associations and Mechanisms in Oncology (GAME‐ON) Network. Five genetic variants reliably associated with circulating 25OHD were used to create a relative genetic measure of 25OHD. In the absence of measured 25OHD, two‐sample Mendelian randomization using individual level outcome data were used to estimate causal odds ratios (OR) for cancer case status per standard deviation increase in log25OHD. Analyses were replicated in an independent population‐based cohort (UK Biobank). In the GAME‐ON study, there was little evidence of a causal association between circulating 25OHD and oral cancer (OR = 0.86 [0.68;1.09], p = 0.22), oropharyngeal cancer (OR = 1.28 [0.72;2.26], p = 0.40) or when sites were combined (OR = 1.01 [0.74;1.40], p = 0.93). Replication in UK Biobank and pooled estimates produced similar results. Our study suggests that a clinically relevant protective effect of 25OHD on oral and oropharyngeal cancer risk is unlikely and supplementation of the general population with 25OHD is unlikely to be beneficial in preventing these cancers.