Oral cancer in Southern India: the influence of body size, diet, infections and sexual practices

Unveiling the anti-cancer mechanisms of calotropin: Insights into cell growth inhibition, cell cycle arrest, and metabolic regulation in human oral squamous carcinoma cells (HSC-3)

Background

Calotropin, a cardiac glycoside obtained from the plant Calotropis gigantea, has demonstrated promising potential as an anti-tumorigenesis compound.

Objective

The main objective of this study was to investigate the potential anti-cancer properties of calotropin against HSC-3 oral squamous cancer cells and to elucidate the underlying mechanisms involved in its action.

Material and method

Calotropin were treated in HSC-3 to evaluate cell viability by MTT assay. Flow cytometry analysis divulged that calotropin G0/G1 phase cell cycle arrest and apoptosis in HSC-3 cells. Calotropin displayed inhibitory properties against aerobic glycolysis, a metabolic alteration using glucose uptaken, lactose production and LDHA activity assays. Furthermore, migration and invasion assays help that calotropin has ability to reduce the migratory and invasive of HSC-3 cells, using transwell and Matrigel assay. Validation of mRNA expression through RT-PCR. Molecular docking was implemented to validate the binding association of calotropin with apoptosis and metastatic regulating targets.

Result

The results exemplify that increasing doses of calotropin effectively hold back the HSC-3 cell progression. Migration and invasion assays help that calotropin has ability to reduce the migratory and invasive of HSC-3 cells, indicating its potential to inhibit cancer metastasis. These results imply that calotropin may influence genes linked to metastasis and apoptosis in order to achieve its beneficial effects on cancer. Docking results provided further support, showing a high binding energy between calotropin and metastasis-mediated pathways.

Conclusion

Overall, our findings shed an experimental evidence on how calotropin inhibits the HSC-3 oral squamous cancer cell growth, highlighting the drug's potential as a treatment for oral cancer. Further, investigation on in-vivo experiment is warranted to explore its potential mechanism of action and to develop a novel drug towards clinical trial.

Is Systemic Immunosuppression a Risk Factor for Oral Cancer? A Systematic Review and Meta-Analysis

Even if the relationship between immunosuppression and increased incidence of systemic cancers is well known, there is less awareness about the risk of developing oral cancer in immunosuppressed patients. The aim of this review was to evaluate the association between immunosuppression and the development of oral cancer. Two authors independently and, in duplicate, conducted a systematic literature review of international journals and electronic databases (MEDLINE via OVID, Scopus, and Web of Science) from their inception to 28 April 2023. The assessment of risk of bias and overall quality of evidence was performed using the Newcastle-Ottawa Scale and GRADE system. A total of 2843 articles was identified, of which 44 met the inclusion criteria and were included in either the qualitative or quantitative analysis. The methodological quality of the included studies was generally high or moderate. The quantitative analysis of the studies revealed that immunosuppression should be considered a risk factor for the development of oral cancer, with a percentage of increased risk ranging from 0.2% to 1% (95% CI: 0.2% to 1.4%). In conclusion, the results suggest that a constant and accurate follow-up should be reserved for all immunosuppressed patients as a crucial strategy to intercept lesions that have an increased potential to evolve into oral cancer.

Influence of dairy products consumption on oral cancer risk: A meta-analysis

Background

The role of dairy product consumption on oral cancer risk is not yet fully clarified. Some studies have observed an inverse association between dairy consumption and oral cancer risk. This study aimed to determine the influence of dairy product consumption (milk, cheese, yogurt, butter) on oral cancer risk.

Methods

A search for studies on dairy products and oral cancer was conducted in the following databases: PubMed (MEDLINE, Cochrane Library), Web of Science (WoS), and Scopus. The estimation of the odds ratio (OR) effect was performed with the generic inverse variance method using the logarithm of the effect with the standard error (SE) and 95% confidence intervals.

Results

Twenty-one studies with 59271 participants (8,300 oral cancer patients and 50971 controls) were included in this meta-analysis. All dairy products significantly reduced oral cancer risk except butter (P=0.16). Milk intake reduced oral cancer risk by 27% (OR: 0.73; P<0.001); yogurt consumption by 25% (OR: 0.75; P<0.001), and cheese consumption by 21% (OR:0.79; P<0.01).

Conclusion

Regular consumption of dairy products reduces oral cancer risk between 21% and 27%.

Modifiable risk factors for oral cavity cancer in non-smokers: A systematic review and meta-analysis

BACKGROUND

Oral cavity cancer (OCC) is traditionally associated with smoking, but there is an increasing prevalence of the disease among non-smokers. This review investigates possible modifiable risk factors in the development of OCC in non-smokers (OCCNS).

METHODS

PubMed, EMBASE, Web of Science, and Scopus were searched for publications prior to June 2021. Comparative studies investigating modifiable OCCNS risk factors were identified following PRISMA guidelines. Publication date, population size, and results were indexed. Study quality was assessed using MINORS (Methodological Index for Non-Randomized Studies). Factors examined by multiple studies were analyzed using random-effect meta-analysis framework.

RESULTS

Literature search resulted in 1,625 unique publications. 52 records met inclusion criterion, investigating alcohol (n = 22), chewing products (n = 18), diet (n = 7), dental health (n = 11), and medical comorbidities (n = 6).

CONCLUSION

This review demonstrates the paucity of large studies investigating OCCNS risk factors. Further investigation is warranted to help clinicians risk-stratify patients without traditional risk factors.

Investigating the effect of sexual behaviour on oropharyngeal cancer risk: a methodological assessment of Mendelian randomization

BACKGROUND

Human papilloma virus infection is known to influence oropharyngeal cancer (OPC) risk, likely via sexual transmission. However, sexual behaviour has been correlated with other risk factors including smoking and alcohol, meaning independent effects are difficult to establish. We aimed to evaluate the causal effect of sexual behaviour on the risk of OPC using Mendelian randomization (MR).

METHODS

Genetic variants robustly associated with age at first sex (AFS) and the number of sexual partners (NSP) were used to perform both univariable and multivariable MR analyses with summary data on 2641 OPC cases and 6585 controls, obtained from the largest available genome-wide association studies (GWAS). Given the potential for genetic pleiotropy, we performed a number of sensitivity analyses: (i) MR methods to account for horizontal pleiotropy, (ii) MR of sexual behaviours on positive (cervical cancer and seropositivity for Chlamydia trachomatis) and negative control outcomes (lung and oral cancer), (iii) Causal Analysis Using Summary Effect estimates (CAUSE), to account for correlated and uncorrelated horizontal pleiotropic effects, (iv) multivariable MR analysis to account for the effects of smoking, alcohol, risk tolerance and educational attainment.

RESULTS

In univariable MR, we found evidence supportive of an effect of both later AFS (IVW OR = 0.4, 95%CI (0.3, 0.7), per standard deviation (SD), p = < 0.001) and increasing NSP (IVW OR = 2.2, 95%CI (1.3, 3.8) per SD, p = < 0.001) on OPC risk. These effects were largely robust to sensitivity analyses accounting for horizontal pleiotropy. However, negative control analysis suggested potential violation of the core MR assumptions and subsequent CAUSE analysis implicated pleiotropy of the genetic instruments used to proxy sexual behaviours. Finally, there was some attenuation of the univariable MR results in the multivariable models (AFS IVW OR = 0.7, 95%CI (0.4, 1.2), p = 0.21; NSP IVW OR = 0.9, 95%CI (0.5 1.7), p = 0.76).

CONCLUSIONS

Despite using genetic variants strongly related sexual behaviour traits in large-scale GWAS, we found evidence for correlated pleiotropy. This emphasizes a need for multivariable approaches and the triangulation of evidence when performing MR of complex behavioural traits.

Milk and dairy products consumption and the risk of oral or oropharyngeal cancer: a meta-analysis

The present meta-analysis was conducted to explore the role of milk and dairy products consumption on oral or oropharyngeal cancer risk. PubMed, Embase and Chinese Wanfang databases were investigated until 30 June 2019. The overall and subgroup associations were pooled with odds ratios (ORs) and 95% confidence intervals (CIs). As a result, the present study involving 4635 cases and 50777 participants from 12 publications suggested that an inverse association was found between milk and dairy products consumption and oral or oropharyngeal cancer risk (OR = 0.74, 95% CI = 0.59–0.92; I² = 65.9%, P_{for heterogeneity}=0.001). Four studies reported milk consumption on oral cancer risk, but no significant association was found (OR = 0.91, 95% CI = 0.61–1.37). Six studies about milk consumption and oropharyngeal cancer risk found that there was a positive association between them (OR = 0.63, 95% CI = 0.44–0.90). In conclusion, findings from our meta-analysis indicated that milk and dairy products consumption may be associated with decreased risk of oral or oropharyngeal cancer.

Fish consumption could reduce the risk of oral cancer in Europeans: A meta-analysis

OBJECTIVE

More and more researches focused on studying the relationship of fish consumption with the risk of oral cancer, among which discrepancies have risen. The current study aimed to evaluate the possible relationship about fish consumption and oral cancer risk.

METHODS

The PubMed, Web of Science and Chinese National Knowledge Infrastructure were searched up to May 31th, 2019. Pooled odds ratios (OR) and 95% confidence intervals (CI) was calculated using a random-effect model by Stata 12.0 software.

RESULTS

A total of 15 publications involving 5211 cases and 70,005 participants were used in the current study. Overall, a significantly reduced association about fish consumption on oral cancer risk was found in all included subjects (OR = 0.74, 95% CI = 0.64-0.85). Subgroup analysis by geographic location suggested that highest category of fish consumption compared with lowest category had an inverse association on oral cancer risk in Europeans only (OR = 0.67, 95% CI = 0.55-0.82), instead of other populations. No publication bias was detected.

CONCLUSIONS

In summary, our results indicated that fish consumption may contribute to the lower development of oral cancer in European populations, instead of other populations.

Egg Consumption and Risk of Upper Aero-Digestive Tract Cancers: A Systematic Review and Meta-Analysis of Observational Studies

Limited data are available that summarize the relation between egg intake and the risk of upper aero-digestive tract (UADT) cancers. This systematic review and meta-analysis was conducted to investigate the association between egg intake and the risk of UADT cancers. Medline/PubMed, ISI web of knowledge, EMBASE, Scopus, and Google Scholar were searched using relevant keywords. Observational studies conducted on humans investigating the association between egg consumption and the risk of UADT cancers were included. Overall, 38 studies with a total of 164,241 subjects (27, 025 cases) were included. Based on 40 effect sizes from 32 case-control studies, we found a 42% increased risk of UADT cancers among those with the highest egg consumption (ranging from ≥1 meal/d to ≥1 time/mo among studies) compared to those with the lowest intake (ranging from 0-20 g/d to never consumed among studies) (overall OR: 1.42; 95% CI: 1.19, 1.68; P < 0.001). However, this association was only evident in hospital-based case-control (HCC) studies (OR = 1.50; 95% CI: 1.34, 1.68; P < 0.001 for 'oropharyngeal and laryngeal cancer' and OR: 1.27; 95% CI: 1.08, 1.50; P = 0.004 for esophageal cancer) and not in population-based case-control (PCC) studies (OR = 1.25; 95% CI: 0.59, 2.67; P = 0.56 for 'oropharyngeal and laryngeal cancer' and OR: 1.29; 95% CI: 0.92, 1.81; P = 0.13 for esophageal cancer). In addition, the association was not significant in prospective cohort studies (overall OR: 0.86; 95% CI: 0.71, 1.04; P = 0.11). Considering individual cancers, a positive association was observed between the highest egg consumption, compared with the lowest, and risk of oropharyngeal (OR: 1.88; 95% CI: 1.61, 2.20; P < 0.001), laryngeal (OR: 1.83; 95% CI: 1.45, 2.32; P < 0.001), oral & pharyngeal & laryngeal (OR: 1.37; 95% CI: 1.12, 1.67; P < 0.001), and esophageal cancers (OR: 1.28; 95% CI: 1.10,1.48; P = 0.001). We also found an inverse association between egg intake and the risk of oral cancer (OR: 0.78; 95% CI: 0.62, 0.99; P = 0.04). In conclusion, high egg consumption (ranging from ≥1 meal/d to ≥1 time/mo among studies) was associated with increased risk of UADT cancers only in HCC studies but not in PCC or prospective cohort studies. PROSPERO registration number: CRD42018102619.

Citrus fruits intake and oral cancer risk: A systematic review and meta-analysis

OBJECTIVE

To quantify the relationship between Citrus intake and risk of cancer of the oral cavity and pharynx.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Ovid MEDLINE, EMBASE, and Web of Science were searched until September 2017. Search terms included Citrus, Citrus aurantifolia, Citrus sinensis, Citrus paradisi, Citrus fruits, Citrus fruits extract, Citrus oil, fruits, oral cancer, mouth cancer, mouth neoplasm.

STUDY SELECTION

The selection of studies and the systematic review were carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A pre-defined inclusion checklist resulted in the inclusion of articles which were (i) published in peer-reviewed scientific journals; (ii) English language; (iii) and included a measure of Citrus fruit intake and risk of oral and pharyngeal cancer. Studies were excluded if (i) preparations derived from other fruits were used, (ii) Citrus intake was combined with intake of other fruits; (iii) in vitro or animal models were used. We also excluded reviews, systematic reviews, meta-analyses, letters, personal opinions, conference abstracts and book chapters.

DATA EXTRACTION

Three reviewers independently performed the extraction of data from studies included.

RESULTS

Seventeen studies met our inclusion criteria and were included in the final review. Pooled analyses showed that those with the highest Citrus fruit intake compared to the lowest intake had a 50% reduction in risk of oral cavity and pharyngeal cancer (OR 0.50; 95% CI 0.43-0.59).

CONCLUSION

The studies included in this review and meta-analysis showed an inverse association between Citrus fruit intake and oral cancer.

Cruciferous Vegetables and Risk of Cancers of the Gastrointestinal Tract

Cancers of the oropharyngeal tissues, oesophagus, stomach, and colorectum are amongst the most common causes of death from cancer throughout the world. Higher consumption of fruits and vegetables is thought to be protective, and cruciferous vegetables are of particular interest because of their unique role as a source of biologically active glucosinolate breakdown products. A literature review of primary studies and meta-analyses indicates that higher consumption of cruciferous vegetables probably reduces the risk of colorectal and gastric cancers by approximately 8% and 19%, respectively. Some studies support the hypothesis that the protective effect against colorectal cancer is modified by genetic polymorphisms of genes regulating the expression of enzymes of the glutathione S-transferase family, but due to contradictory findings the evidence is currently inconclusive. Despite these promising findings, future epidemiological research on the protective effects of cruciferous plants will depend critically upon accurate measurement of dietary exposure, both to the vegetables themselves, and to their active constituents. The development of sensitive chemical assays has facilitated the measurement of urinary excretion of isothiocyanate metabolites as an objective biomarker of intake, but sampling strategies need to be optimized in order to assess long-term exposures at the population level.

Dietary score and the risk of oral cancer: a case-control study in southeast China

This study aims to develop a simple dietary score to comprehensively evaluate the role of diet in the risk of oral cancer. A case-control study including 930 oral cancer cases and 2667 frequency-matched controls was performed in Fujian, China. Unconditional logistic regression model was used to estimate the effects of dietary factors on oral cancer. After adjustment for potential confounders, less intake of domestic meat (< 3 times per week), fish (< 3 times per week), seafood (< 3 times per week), leafy vegetables (< 1 time per day), other vegetables (< 1 time per day), fruits (< 3 times per week), milk and dairy products (< 1 time per week) and eggs (< 5 times per week) were significant risk factors for oral cancer. Then these variables were incorporated to establish dietary risk score. Assessed by the receiver operating characteristic curve, the score showed a satisfactory discriminatory capacity, with an area under the curve of 0.682 (95% CI: 0.662–0.702). Moreover, the score was positively associated with the risk of oral cancer as quartiles, and the association was apparently stronger in tobacco smokers or alcohol drinkers. Additionally, there were significant multiplicative interactions between the score and tobacco smoking or alcohol drinking for oral cancer. In the present study, a convenient dietary score with satisfactory discriminatory capacity was developed to assess the collected effect of dietary factors on oral cancer, which could provide a new strategy for the prevention of oral cancer through changing in dietary habits.

Associations between oral hygiene habits, diet, tobacco and alcohol and risk of oral cancer: A case-control study from India

OBJECTIVE

This study examines the association between the incidence of oral cancer in India and oral hygiene habits, diet, chewing and smoking tobacco, and drinking alcohol. We also assessed the effects of oral hygiene habits with oral cancer risk among chewers versus never chewers.

METHODS

A hospital-based case-control study was conducted in Pune, India, based on face-to-face interviews, anthropometry, and intra-oral examinations conducted for 187 oral cancer cases and 240 controls.

RESULTS

Poor oral hygiene score was associated with a significant risk of oral cancer (adjusted OR=6.98; 95%CI 3.72-13.05). When stratified by tobacco-chewing habit, the poor oral hygiene score was a significant risk factor only among ever tobacco chewers (adjusted OR=14.74; 95%CI 6.49-33.46) compared with never chewers (adjusted OR=0.71; 95%CI 0.14-3.63). Dental check-ups only at the time of pain by ever-chewers with poor oral hygiene was associated with an elevated risk (adjusted OR=4.22; 95%CI 2.44-7.29), while consumption of green, yellow, and cruciferous vegetables and citrus fruits was protective. A linear dose-response association was observed between oral cancer and chewing tobacco in terms of age at initiation, duration, and frequency of chewing per day (P<0.001). Smoking more than 10 bidis/cigarettes per day (adjusted OR=2.74; 95%CI 1.28-5.89) and for a duration >25 years (adjusted OR=2.31; 95%CI 1.14-4.71) elevated the risk of oral cancer.

CONCLUSION

Good oral hygiene habits - as characterized by healthy gums, brushing more than once daily, use of toothpaste, annual dental check-ups, and a minimal number of missing teeth - can reduce the risk of oral cancer significantly. In addition to refraining from chewing/smoking tobacco, a diet adequate in fruits and vegetables may protect against the disease.

Oral sex and human papilloma virus-related head and neck squamous cell cancer: a review of the literature

Head neck squamous cell carcinomas (HNSCCs) are a significant cause of morbidity and mortality all around the world. Just like tobacco and alcohol, Human papilloma virus (HPV) infection is now recognized to play a role in the pathogenesis of a subset of HNSCCs. Unprotected sexual behaviours with the HPV carrier plays an important role in transmission of this virus. The global incidence of head and neck cancers is declining, but the incidence of HPV related head and neck cancers is rapidly increasing over the last few decades. However, most institutions do not mandate documentation of sexual history or counselling of patients regarding sexual practices like they do for tobacco and alcohol addictions in HNSCC patients. The aim of this review of literature is to analyse if there is a strong evidence to correlate oral sex with HPV related HNSCC and counsel the patient's regarding sexual behaviours.

Intake of meat and fish and risk of head-neck cancer subtypes in the Netherlands Cohort Study

PURPOSE

To date, the role of meat and fish intake in head-neck cancer (HNC) etiology is not well understood and prospective evidence is limited. This prompted us to study the association between meat, fish, and HNC subtypes, i.e., oral cavity cancer (OCC), oro- and hypopharyngeal cancer (OHPC), and laryngeal cancer (LC), within the Netherlands Cohort Study (NLCS).

METHODS

In 1986, 120,852 participants (aged 55-69 years) completed a baseline 150-item food frequency questionnaire (FFQ), from which daily meat and fish intake were calculated. After 20.3 years of follow-up, 430 HNC overall (134 OCC, 90 OHPC and 203 LC) cases and 4,111 subcohort members were found to be eligible for case-cohort analysis. Multivariate hazard ratios were calculated using Cox's proportional hazards model within quartiles of energy-adjusted meat and fish intake.

RESULTS

Processed meat intake, but not red meat intake, was positively associated with HNC overall [HR(Q4 vs. Q1) = 1.46, 95% CI 1.06-2.00; ptrend = 0.03]. Among HNC subtypes, processed meat was positively associated with OCC, while no associations were found with OHPC and LC. Fish intake was not associated with HNC risk. Tests for interaction did not reveal statistically significant interaction between meat, fish, and alcohol or smoking on HNC overall risk.

CONCLUSIONS

In this large cohort study, processed meat intake was positively associated with HNC overall and HNC subtype OCC, but not with OHPC and LC.

Oral and oropharyngeal cancer and the role of sexual behaviour: a systematic review

OBJECTIVES

This systematic review identified and evaluated the evidence for the role of sexual behaviours in the development of oropharyngeal cancers (OPCs) and oral cavity cancers (OCCs).

METHODS

Following the PRISMA guidelines, we identified observational and interventional studies reporting associations between several different sexual behaviours and OPC or OCC. Study quality was assessed independently by two reviewers using a validated scoring system.

RESULTS

From 513 papers identified, 21, reporting on 20 studies, fulfilled the inclusion criteria. Two cohort studies were rated as moderate quality. The 18 case-control studies were rated as weak; nine comparing people with OPC or OCC to people without cancer, eight comparing HPV-positive to HPV-negative cancer patients and one comparing OPCs to other head and neck cancers. One study was a pooled analysis of seven of the included studies with some additional information. Twelve sexual behaviours were assessed and 69 associations reported. The studies differed in the comparisons made, the sexual behaviours assessed, and how these were reported and categorized, so no quantitative meta-analyses were appropriate. Most studies combined OPC and OCC. Several significantly increased risks were seen with a high number of lifetime sexual partners (nine studies) and with the practice of oral sex (five studies), although two studies found a significant negative association with OCC and ever performing oral sex. Two cohort studies of men and women in homosexual relationships found increases in oral cancer risk, and a cohort study of men married to women who had a history of cervical cancer also showed an increased risk of oral cancers. Results for other sexual behaviours were limited and inconsistent, and these included the following: younger age at first sexual intercourse, number of lifetime oral sex partners, the practice of oral-anal sex, the number of oral-anal sex partners, and ever performing anal sex. Only one study assessed casual sex, never or rare use of a condom and having a sexual partner with a history of genital warts, finding significant associations in the two former behaviours.

CONCLUSION

The current evidence for sexual behaviours being risk factors for oral and oropharyngeal cancer is limited and inconsistent. Evidence suggests that the number of sexual partners and performing oral sex are associated with a greater risk. Furthermore men whose partners have had cervical cancer may have an increased risk. More studies looking at OPC specifically will be useful to determine whether these behaviours are subsite-selective.

Burden of preventable cancers in India: Time to strike the cancer epidemic

India has a rapidly growing population inflicted with cancer diagnosis. From an estimated incidence of 1.45 million cases in 2016, the cancer incidence is expected to reach 1.75 million cases in 2020. With the limitation of facilities for cancer treatment, the only effective way to tackle the rising and humongous cancer burden is focusing on preventable cancer cases. Approximately, 70% of the Indian cancers (40% tobacco related, 20% infection related and 10% others) are caused by potentially modifiable and preventable risk factors. We review these factors with special emphasis on the Indian scenario. The results may help in designing preventive strategies for a wider application.

Apple intake and cancer risk: a systematic review and meta-analysis of observational studies

OBJECTIVE

Conflicting results on the association between fruit consumption and cancer risk have been reported. Little is known about the cancer preventive effects of different fruit types. The present meta-analysis investigates whether an association exists between apple intake and cancer risk.

DESIGN

Relevant observational studies were identified by literature search (PubMed, Web of Science and Embase). A random-effect model was used to estimate the cancer risk in different anatomical sites. Between-study heterogeneity and publication bias were assessed using adequate statistical tests.

RESULTS

Twenty case-control (three on lung, five on colorectal, five on breast, two on oesophageal, three on oral cavity, two on prostate and one each on pancreas, bladder, larynx, ovary, kidney and brain cancer) and twenty-one cohort (seven on lung, two on colorectal, three on breast and one each on oesophageal, pancreas, bladder, kidney, endometrial, head-neck, urothelial and stomach cancer) studies met the inclusion criteria. Comparing the highest v. lowest level of apple consumption, the reduction of lung cancer risk was statistically highly significant in both case-control (OR=0·75; 95% CI 0·63, 0·88; P=0·001, I 2=0 %) and cohort studies (relative risk=0·89; 95% CI 0·84, 0·94; P<0·001, I 2=53 %). Instead, in the case of colorectal (OR=0·66; 95% CI 0·54, 0·81; P<0·001, I 2=55%), breast (OR=0·79; 95% CI 0·73, 0·87; P<0·001, I 2=1 %) and overall digestive tract (OR=0·50; 95% CI 0·36, 0·69; P<0·001, I 2=90 %) cancers a significant preventive effect of apples was found only in case-control studies while prospective studies indicated no effect. No evidence of publication bias could be detected for colorectal, oral cavity, oesophageal and breast cancer. However, some confounding effects may be present and related to the consumption of other fruit which have not been considered as adjusting factors.

CONCLUSIONS

The present meta-analysis indicates that consumption of apples is associated with a reduced risk of cancer in different anatomical sites.

Estimating the effect of childhood socioeconomic disadvantage on oral cancer in India using marginal structural models

BACKGROUND

Early life socioeconomic disadvantage could affect adult health directly or indirectly. To the best of our knowledge, there are no studies of the direct effect of early life socioeconomic conditions on oral cancer occurrence in adult life.

METHODS

We conducted a multicenter, hospital-based, case-control study in India between 2011 and 2012 on 180 histopathologically confirmed incident oral and/or oropharyngeal cancer cases, aged 18 years or more, and 272 controls that included hospital visitors, who were not diagnosed with any cancer in the same hospitals. Life-course data were collected on socioeconomic conditions, risk factors, and parental behavior through interview employing a life grid. The early life socioeconomic conditions measure was determined by occupation of the head of household in childhood. Adult socioeconomic measures included participant's education and current occupation of the head of household. Marginal structural models with stabilized inverse probability weights were used to estimate the controlled direct effects of early life socioeconomic conditions on oral cancer.

RESULTS

The total effect model showed that those in the low socioeconomic conditions in the early years of childhood had 60% (risk ratio [RR] = 1.6 [95% confidence interval {CI} = 1.4, 1.9]) increased risk of oral cancer. From the marginal structural models, the estimated risk for developing oral cancer among those in low early life socioeconomic conditions was 50% (RR = 1.5 [95% CI = 1.4, 1.5]), 20% (RR = 1.2 [95% CI = 0.9, 1.7]), and 90% (RR = 1.9 [95% CI = 1.7, 2.2]) greater than those in the high socioeconomic conditions when controlled for smoking, chewing, and alcohol, respectively. When all the three mediators were controlled in a marginal structural model, the RR was 1.3 (95% CI = 1.0, 1.6).

CONCLUSION

Early life low socioeconomic condition had a controlled direct effect on oral cancer when smoking, chewing tobacco, and alcohol were separately adjusted in marginal structural models.

HPV-associated head and neck cancers in the Asia Pacific: A critical literature review & meta-analysis

BACKGROUND

Malignancies of the upper aero-digestive tract are a major public health problem, especially in the Asia Pacific. Certain Human papillomaviruses (HPVs) are well-established risk factors for carcinoma of the uterine cervix and for a subset of head and neck carcinomata: however their true importance in different populations and anatomical subsites remains unclear. The major risk factors in Asia Pacific remain smoked/smokeless tobacco, areca nut, alcohol abuse and poor diet, with limited evidence for HPVs. We review published studies of association of HPV with anatomical site-specific Head & Neck Squamous Cell Carcinoma (HNSCC) in these populations and attempt a meta-analysis.

MATERIALS AND METHODS

From MEDLINE/PubMed/WEB-of SCIENCE/EMBASE/Scopus databases we found 67 relevant studies with a total of 7280 cases: 15 case-control studies met our inclusion criteria for meta-analysis, totaling 1106 cases & 638 controls. HPV detection rates, sample site and size, and methods of tissue preservation and HPV detection were tabulated for each study.

RESULTS

Studies were heterogeneous in terms of sample selection and method of detection of HPVs. Most were of limited quality. Averaging data from 67 studies of HNSCC, the prevalence of HPV of any subtype is approximately 36%. PCR (polymerase chain reaction) was the most used detection method and HPV16 the most common genotype reported. Meta-analyses of case-control studies from this region reveal significant heterogeneity but suggest higher HPV prevalence in oropharyngeal cancer (OR: 14.66; 95%CI: 6.09-35.26) compared to oral cavity cancer and laryngeal cancer; (OR: 4.06; 95%CI: 3.05-5.39 & OR: 3.23; 95%CI: 1.37-7.61) respectively.

CONCLUSION

In view of the significant association of HPV with HNSCC, studies with accurate subsite classification and more sensitive detection methods are necessary. Accurate data from this geographical region are essential to inform public health policies and treatment decisions, especially as studies from Europe and North America reveal HPV-driven cancers to be less aggressive, permitting treatment de-intensification.

Sexual behaviours and head and neck cancer: A systematic review and meta-analysis

Human papillomaviruses (HPV) are associated with head and neck cancers (H&NC). Transmission of HPV to the upper aerodigestive tract occurs plausibly through sexual contact, although epidemiologic evidence on the role of sexual behaviours in H&NC aetiology is inconsistent. We conducted a meta-analysis of studies examining the association between four indicators of sexual behaviours (number of sexual partners and oral sex partners, oral sex practice, and age at first intercourse) and H&NC. Summary odds ratios (OR) and 95% confidence intervals (CI) were estimated using fixed and random effects models for each indicator, contrasting 'highest' to 'lowest', 'ever' to 'never', or 'youngest' to 'oldest' categories. Twenty case-control studies were included out of 3838 identified publications. Using random effects models, summary ORs suggested an increased risk of H&NC for number of sexual partners [OR=1.29, 95% CI: 1.02-1.63] (19 studies) and number of oral sex partners [OR=1.69, 95% CI: 1.00-2.84] (5 studies), whereas no effect was observed with oral sex practice [OR=1.09, 95% CI: 0.88-1.35] (17 studies) and age at first intercourse [OR=1.40, 95% CI: 0.71-2.79] (6 studies). For number of sexual partners and oral sex practice, which were assessed in more studies, we further excluded studies contributing to heterogeneity and those not adjusted for age, sex, smoking, and alcohol consumption. The summary ORs were 0.95 (95% CI: 0.75-1.20) for number of sexual partners and 1.03 (95% CI: 0.84-1.26) for oral sex practice. Our findings highlight that observed associations might be partly attributed to confounding effects of sociodemographic and behavioural factors.

Oral sex and risk of oral cancer: a meta-analysis of observational studies

OBJECTIVE

Association between oral sex and oral cancer is a highlighted topic all the time; however, many published epidemiological studies remain failed to obtain a consistent conclusion. We performed this meta-analysis to ascertain whether oral sex is a risk factor or a risk marker for oral cancer.

METHOD

The PubMed database was searched up to 30 August 2013 (latest updated on 21 December 2014) for relevant observational studies that tested the association between oral sex and oral cancer risk. After data extraction from eligible studies, the meta-analysis was conducted using the Comprehensive Meta-Analysis software.

RESULTS

Finally we yielded six case-control studies and one cross-sectional study with 5553 individuals. The results based on random-effects model indicated that there was no significant association between oral sex and risk of oral cancer (OR 1.15, 95% CI 0.86 to 1.54; P = 0.33). Sensitivity analysis showed that the result was robust and subgroups analyses also revealed similar results. Publication bias was not detected.

CONCLUSION

Current evidence suggests that oral sex is a risk marker rather than an independent risk factor for oral cancer. However, the practitioners should assure they are without sexually transmitted diseases and with good oral health, and at least cleaned carefully and thoroughly before oral sex.

Epidemiology of oral cancer in Asia in the past decade--an update (2000-2012)

The prevalence of oral cancers (OC) is high in Asian countries, especially in South and Southeast Asia. Asian distinct cultural practices such as betel-quid chewing, and varying patterns of tobacco and alcohol use are important risk factors that predispose to cancer of the oral cavity. The aim of this review is to provide an update on epidemiology of OC between 2000 and 2012. A literature search for this review was conducted on Medline for articles on OC from Asian countries. Some of the articles were also hand searched using Google. High incidence rates were reported from developing nations like India, Pakistan, Bangladesh, Taiwan and Sri Lanka. While an increasing trend has been observed in Pakistan, Taiwan and Thailand, a decreasing trend is seen in Philippines and Sri Lanka. The mean age of occurrence of cancer in different parts of oral cavity is usually between 51-55 years in most countries. The tongue is the leading site among oral cancers in India. The next most common sites in Asian countries include the buccal mucosa and gingiva. The 5 year survival rate has been low for OC, despite improvements in diagnosis and treatment. Tobacco chewing, smoking and alcohol are the main reasons for the increasing incidence rates. Low socioeconomic status and diet low in nutritional value lacking vegetables and fruits contribute towards the risk. In addition, viral infections, such as HPV and poor oral hygiene, are other important risk factors. Hence, it is important to control OC by screening for early diagnosis and controlling tobacco and alcohol use. It is also necessary to have cancer surveillance at the national-level to collect and utilise data for cancer prevention and control programs.

The role of sexual behavior in head and neck cancer: implications for prevention and therapy

HPV-positive oropharyngeal squamous cell carcinoma (HPV-OSCC) is associated with oral sexual behaviors. The sharp rise in incidence of HPV-OSCC in the USA has been attributed to changes in sexual norms over the past five decades, with lower age at sexual debut and higher numbers of sexual partners per individual. In addition, variations in HPV-OSCC prevalence by race, age cohort and gender may be attributable to differences in oral sexual behaviors among these groups. Oral HPV infection is the putative precursor to HPV-OSCC. Risk factors for oral HPV incidence, prevalence, clearance and persistence are crucial to understanding how, and in whom, oral HPV infection progresses to malignancy. Future investigation should focus on elucidating the natural history of oral HPV infection persistence and malignant transformation, developing effective screening tools and exploring opportunities for prevention such as vaccination and public health education.

Phenethyl isothiocyanate induces DNA damage-associated G2/M arrest and subsequent apoptosis in oral cancer cells with varying p53 mutations

Phenethyl isothiocyanate (PEITC) is a naturally occurring cruciferous vegetable-derived compound that inhibits cell growth and induces apoptosis in oral cancer cells. However, the exact mechanism of PEITC action has not been fully elucidated. This study investigated the molecular mechanism and anticancer potential of PEITC in oral squamous cell carcinoma (OSCC) cells with various p53 statuses. PEITC inhibited the growth of OC2, SCC4, and SCC25 cells (functional p53 mutants) in a dose-dependent manner with low toxicity to normal cells. Treatment with PEITC induced reactive oxygen species production, nitric oxide generation, and GSH depletion and triggered DNA damage response as evidenced by flow cytometry, 8-OHdG formation, and comet assay. Furthermore, the subsequent activation of ATM, Chk2, and p53 as well as the increased expression of downstream proteins p21 and Bax resulted in a G2/M phase arrest by inhibiting Cdc25C, Cdc2, and cyclin B1. The PEITC-induced apoptotic cell death, following a diminished mitochondrial transmembrane potential, reduced the expression of Bcl-2 and Mcl-1, released mitochondrial cytochrome c, and activated caspase 3 and PARP cleavage. The p53 inhibitor pifithrin-α and the antioxidants N-acetylcysteine and glutathione (GSH) protected the cells from PEITC-mediated apoptosis. However, mito-TEMPO, catalase, apocynin, and L-NAME did not prevent PEITC-induced cell death, suggesting that PEITC induced G2/M phase arrest and apoptosis in oral cancer cells via a GSH redox stress and oxidative DNA damage-induced ATM-Chk2-p53-related pathway. These results provide new insights into the critical roles of both GSH redox stress and p53 in the regulation of PEITC-induced G2/M cell cycle arrest and apoptosis in OSCCs.

Meat consumption and risk of oral cavity and oropharynx cancer: a meta-analysis of observational studies

PURPOSE

High meat consumption, especially red and processed meat consumption is associated with an increased risk of several cancers, however, evidence for oral cavity and oropharynx cancer is limited. Thus, we performed this meta-analysis to determine the association between intakes of total meat, processed meat, red meat, and white meat, and the risk of oral cavity and oropharynx cancer.

METHODS

Electronic search of Pubmed, Embase, and Cochrane Library Central database was conducted to select relevant studies. Fixed-effect and random-effect models were used to estimate summary relative risks (RR) and the corresponding 95% confidence intervals (CIs). Potential sources of heterogeneity were detected by meta-regression. Subgroup analyses and sensitivity analysis were also performed.

RESULTS

12 case-control studies and one cohort study were included in the analyses, including 501,730 subjects and 4,104 oral cavity and oropharynx cancer cases. Pooled results indicated that high consumption of total meat, red meat, and white meat were not significantly associated with increased risk of oral cavity and oropharynx cancer (RR = 1.14, 95% CI[0.78-1.68]; RR = 1.05, 95% CI[0.66, 1.66] and RR = 0.81, 95% CI[0.54, 1.22], respectively), while the high consumption of processed meat was significantly associated with a 91% increased risk of oral cavity and oropharynx cancer (RR = 1.91, 95% CI [1.19-3.06]). Sensitivity analysis indicated that no significant variation in combined RR by excluding any of the study, confirming the stability of present results.

CONCLUSIONS

The present meta-analysis suggested that high consumption of processed meat was significantly associated with an increased risk of oral cavity and oropharynx cancer, while there was no significantly association between total meat, red meat or white meat and the risk of oral cavity and oropharynx cancer. More prospective cohort studies are warranted to confirm these associations.

Genetic variants in nicotine addiction and alcohol metabolism genes, oral cancer risk and the propensity to smoke and drink alcohol: a replication study in India

BACKGROUND

Genetic variants in nicotinic acetylcholine receptor and alcohol metabolism genes have been associated with propensity to smoke tobacco and drink alcohol, respectively, and also implicated in genetic susceptibility to head and neck cancer. In addition to smoking and alcohol, tobacco chewing is an important oral cancer risk factor in India. It is not known if these genetic variants influence propensity or oral cancer susceptibility in the context of this distinct etiology.

METHODS

We examined 639 oral and pharyngeal cancer cases and 791 controls from two case-control studies conducted in India. We investigated six variants known to influence nicotine addiction or alcohol metabolism, including rs16969968 (CHRNA5), rs578776 (CHRNA3), rs1229984 (ADH1B), rs698 (ADH1C), rs1573496 (ADH7), and rs4767364 (ALDH2).

RESULTS

The CHRN variants were associated with the number of chewing events per day, including in those who chewed tobacco but never smoked (P =  0.003, P =  0.01 for rs16969968 and rs578776 respectively). Presence of the variant allele contributed to approximately 13% difference in chewing frequency compared to non-carriers. While no association was observed between rs16969968 and oral cancer risk (OR =  1.01, 95% CI =  0.83- 1.22), rs578776 was modestly associated with a 16% decreased risk of oral cancer (OR =  0.84, 95% CI =  0.72- 0.98). There was little evidence for association between polymorphisms in genes encoding alcohol metabolism and oral cancer in this population.

CONCLUSION

The association between rs16969968 and number of chewing events implies that the effect on smoking propensity conferred by this gene variant extends to the use of smokeless tobacco.

Human papillomavirus and diseases of the upper airway: head and neck cancer and respiratory papillomatosis

Human papillomavirus (HPV) infection is causally associated with benign and malignant diseases of the upper airway, including respiratory papillomatosis and oropharyngeal cancer. Low-risk HPV types 6 and 11 are the predominant cause of papillomatosis, whereas only HPV16 definitively satisfies both molecular and epidemiological causal criteria as a carcinogenic or high-risk type in the upper airway. HPV16 E6/E7 mRNA expression and integration are observed predominantly among oropharyngeal cancers, and experimental models have shown E6/E7 expression to be necessary for the initiation and maintenance of the malignant phenotype of these cancers. From an epidemiological perspective, a strong and consistent association between markers of HPV16 exposure and oropharyngeal cancer has been demonstrated in numerous case-control studies. HPV-positive oropharyngeal cancers have also been shown to be distinct from HPV-negative head and neck squamous cell cancers with regard to risk-factor profiles, molecular genetic alterations, population-level incidence trends over time, and prognosis. Tumor HPV status (as determined by certain HPV16 in situ hybridization assays or certain p16 immunohistochemistry assays) is the strongest determinant of survival for patients with local-regionally advanced oropharyngeal cancer: patients with HPV-positive cancer have at least a 50% improvement in overall survival at 5 years, which is equivalent to an approximate 30% difference in absolute survival. Thus, HPV status determination is now part of the routine diagnostic evaluation for prognostication. Preliminary evidence indicates that a small proportion of head and neck cancers may be caused by additional HPV types (e.g., 18, 31, 33, 35) and that HPV-caused cancers may rarely arise from non-oropharyngeal sites (e.g., the oral cavity, nasopharynx, and larynx). Whether or not HPV vaccination has the potential to prevent oral HPV infections that lead to cancer or papillomatosis in the upper airway is currently unknown, as is the potential for secondary prevention with HPV detection. This article forms part of a special supplement entitled "Comprehensive Control of HPV Infections and Related Diseases" Vaccine Volume 30, Supplement 5, 2012.

Do tobacco and alcohol modify protective effects of diet on oral carcinogenesis?

Recent systematic reviews concluded that the frequent consumption of fruits and vegetables is inversely associated with the risk of oral cancer. We assessed this association, specifically comparing results obtained to nonsmokers and smokers, as well to nondrinkers and drinkers. We conducted a case-control study involving 296 patients with oral squamous cell carcinoma (cases) attended in 3 major hospitals of São Paulo, Brazil, paired with 296 controls, recruited from outpatient units of the same hospitals. Multivariate models assessed the effect of fruits and salads according to smoking and drinking. The intake of fruit was associated with the prevention of the disease in the specific assessment among light [odds ratio (OR) = 0.46; 95% confidence interval (CI) = 0.27-0.78) and heavy (OR = 0.30; 95% CI = 0.14-0.65) smokers. The same was observed for vegetables consumption. For nonsmokers, no fruit (OR = 50; 95% CI = 0.22-1.12) or vegetable (for tomato, OR = 0.53; 95% CI = 0.31-0.93) was associated with reduced risk of oral and oropharyngeal cancer. Similar results were found in the stratified analysis according to drinking status with OR = 0.51 (95% CI = 0.30-0.87) and 0.18 for fruits (95% CI = 0.07-0.45), respectively, for light and heavy drinkers. This observation suggests that the protective effect of fruit and salad intake may modulate the deleterious effects from tobacco and alcohol.

Epidemiology of human papillomavirus-related head and neck cancer

Human papillomavirus (HPV) is now recognized to cause a subset of head and neck squamous cell carcinomas (HNSCC). Although excessive tobacco and alcohol use continue to be important risk factors for HNSCC, epidemiologic studies suggest that more than 25% of HNSCC are now caused by HPV. The incidence of HPV-related HNSCC is increasing, highlighting the need to understand the oral HPV infections causing these cancers. This article reviews the evidence for a causal association between HPV and HNSCC, examines the changing epidemiologic trends of HNSCC, and discusses what is currently known about oral HPV infection, natural history, and transmission.

Diet and the risk of head and neck cancer: a pooled analysis in the INHANCE consortium

We investigated the association between diet and head and neck cancer (HNC) risk using data from the International Head and Neck Cancer Epidemiology (INHANCE) consortium. The INHANCE pooled data included 22 case-control studies with 14,520 cases and 22,737 controls. Center-specific quartiles among the controls were used for food groups, and frequencies per week were used for single food items. A dietary pattern score combining high fruit and vegetable intake and low red meat intake was created. Odds ratios (OR) and 95% confidence intervals (CI) for the dietary items on the risk of HNC were estimated with a two-stage random-effects logistic regression model. An inverse association was observed for higher-frequency intake of fruit (4th vs. 1st quartile OR = 0.52, 95% CI = 0.43-0.62, p (trend) < 0.01) and vegetables (OR = 0.66, 95% CI = 0.49-0.90, p (trend) = 0.01). Intake of red meat (OR = 1.40, 95% CI = 1.13-1.74, p (trend) = 0.13) and processed meat (OR = 1.37, 95% CI = 1.14-1.65, p (trend) < 0.01) was positively associated with HNC risk. Higher dietary pattern scores, reflecting high fruit/vegetable and low red meat intake, were associated with reduced HNC risk (per score increment OR = 0.90, 95% CI = 0.84-0.97).

An examination of male and female odds ratios by BMI, cigarette smoking, and alcohol consumption for cancers of the oral cavity, pharynx, and larynx in pooled data from 15 case-control studies

BACKGROUND

Greater tobacco smoking and alcohol consumption and lower body mass index (BMI) increase odds ratios (OR) for oral cavity, oropharyngeal, hypopharyngeal, and laryngeal cancers; however, there are no comprehensive sex-specific comparisons of ORs for these factors.

METHODS

We analyzed 2,441 oral cavity (925 women and 1,516 men), 2,297 oropharynx (564 women and 1,733 men), 508 hypopharynx (96 women and 412 men), and 1,740 larynx (237 women and 1,503 men) cases from the INHANCE consortium of 15 head and neck cancer case-control studies. Controls numbered from 7,604 to 13,829 subjects, depending on analysis. Analyses fitted linear-exponential excess ORs models.

RESULTS

ORs were increased in underweight (< 18.5 BMI) relative to normal weight (18.5-24.9) and reduced in overweight and obese categories (≥ 25 BMI) for all sites and were homogeneous by sex. ORs by smoking and drinking in women compared with men were significantly greater for oropharyngeal cancer (p < 0.01 for both factors), suggestive for hypopharyngeal cancer (p = 0.05 and p = 0.06, respectively), but homogeneous for oral cavity (p = 0.56 and p = 0.64) and laryngeal (p = 0.18 and p = 0.72) cancers.

CONCLUSIONS

The extent that OR modifications of smoking and drinking by sex for oropharyngeal and, possibly, hypopharyngeal cancers represent true associations, or derive from unmeasured confounders or unobserved sex-related disease subtypes (e.g., human papillomavirus-positive oropharyngeal cancer) remains to be clarified.

Sexual behaviours and the risk of head and neck cancers: a pooled analysis in the International Head and Neck Cancer Epidemiology (INHANCE) consortium

BACKGROUND

Sexual contact may be the means by which head and neck cancer patients are exposed to human papillomavirus (HPV).

METHODS

We undertook a pooled analysis of four population-based and four hospital-based case-control studies from the International Head and Neck Cancer Epidemiology (INHANCE) consortium, with participants from Argentina, Australia, Brazil, Canada, Cuba, India, Italy, Spain, Poland, Puerto Rico, Russia and the USA. The study included 5642 head and neck cancer cases and 6069 controls. We calculated odds ratios (ORs) of associations between cancer and specific sexual behaviours, including practice of oral sex, number of lifetime sexual partners and oral sex partners, age at sexual debut, a history of same-sex contact and a history of oral-anal contact. Findings were stratified by sex and disease subsite.

RESULTS

Cancer of the oropharynx was associated with having a history of six or more lifetime sexual partners [OR = 1.25, 95% confidence interval (CI) 1.01, 1.54] and four or more lifetime oral sex partners (OR = 2.25, 95% CI 1.42, 3.58). Cancer of the tonsil was associated with four or more lifetime oral sex partners (OR = 3.36, 95 % CI 1.32, 8.53), and, among men, with ever having oral sex (OR = 1.59, 95% CI 1.09, 2.33) and with an earlier age at sexual debut (OR = 2.36, 95% CI 1.37, 5.05). Cancer of the base of the tongue was associated with ever having oral sex among women (OR = 4.32, 95% CI 1.06, 17.6), having two sexual partners in comparison with only one (OR = 2.02, 95% CI 1.19, 3.46) and, among men, with a history of same-sex sexual contact (OR = 8.89, 95% CI 2.14, 36.8).

CONCLUSIONS

Sexual behaviours are associated with cancer risk at the head and neck cancer subsites that have previously been associated with HPV infection.

Dairy products, leanness, and head and neck squamous cell carcinoma

BACKGROUND

As part of a population-based case-control study, we investigated the association of food groups and micronutrients estimated from a validated food frequency questionnaire (FFQ) with the risk of development of head and neck squamous cell carcinoma (HNSCC).

METHODS

Incident cases were accrued through Boston area hospitals from 1999 to 2003, and neighborhood controls were selected and matched by location, age, and sex. There were 504 cases and 717 controls enrolled, who completed the FFQ.

RESULTS

We observed a positive association between the consumption of dairy products and HNSCC. The odds of HNSCC in the highest quintile of dairy intake was 1.64 (95% CI: 1.09-2.46), compared with subjects in the lowest quintile. There was a significant association between leanness with HNSCC. The odds of cancer among the leanest subjects was 5.8 (95%CI: 3.2-10.6) compared with a healthy BMI. Finally, intake of animal fat was positively associated with an elevation in cancer risk. The odds of HNSCC for high animal fat intake were 1.50 (0.99-2.27).

CONCLUSIONS

Our data suggest that consumption of fruits and vegetables is not universally protective for HNSCC and that other food groups and nutrients may influence the risk for developing this disease.

Dietary risk factors for hypopharyngeal cancer in India

OBJECTIVE

The Indian subcontinent has among the highest rates of hypopharyngeal cancer worldwide. The purpose of this study was to examine the associations between the Indian diet and hypopharyngeal cancer.

METHODS

We used data from a hospital-based case-control study of 513 incident hypopharyngeal cancers and 718 controls from four centers in India. Dietary information was assessed using a 67-item semi-quantitative food frequency questionnaire. Intakes of related foods were combined across food groups and were categorized by quartile. We used unconditional logistic regression modeling, stratified by ever tobacco use, to analyze the association between food intakes and hypopharyngeal cancer.

RESULTS

Among persons who had ever smoked or chewed tobacco, protective associations were seen at the highest quartiles of total fruit intake (OR = 0.37, 0.20-0.69), curds (OR = 0.35, 0.17-0.69), and leafy green (OR = 0.25, 95% CI 0.13-0.51), root (OR = 0.22, 95% CI 0.11-0.43), and cruciferous vegetable intakes (OR = 0.41, 0.20-0.84). Results were similar, although not as robust, among persons who had never smoked or chewed tobacco. An increased risk of disease was seen among tobacco users who drank milk daily (OR = 1.84, 1.14-2.98).

CONCLUSIONS

Dietary factors might contribute to the high risk of hypopharyngeal cancer observed in India.

Line region hypomethylation is associated with lifestyle and differs by human papillomavirus status in head and neck squamous cell carcinomas

Genomic hypomethylation is a hallmark of essentially all cancers, but the degree of this hypomethylation differs among individual tumors. Little work has explored what leads to these differences and or asked whether they are clinically meaningful. In this study of head and neck squamous cell carcinoma, we assessed hypomethylation in tumors using a semiquantitative fragment analysis approach to determine the relative methylation status of the line retroviral element LRE1 (Line-1.2). Because this is an established marker of genomic methylation status, we examined the relationship between the relative methylation, patient demographics, and other risk factors for head and neck squamous cell carcinoma. We determined relative methylation status for 303 patients, 193 of which had complete data for all variables of interest. Using a generalized linear model, we found that patient body mass index was significantly positively associated with tumor LRE1 methylation level. Smoking duration, particularly in tumors lacking human papillomavirus (HPV) DNA, was significantly negatively associated with relative methylation level. Having previously assessed relative methylation in blood-derived DNA, we compared tumor with the blood DNA methylation level and observed these to be independent. Finally, the lower LRE1 methylation in patients whose tumors were HPV DNA negative was associated with poorer patient survival (hazard ratio, 1.6; 95% confidence interval, 1.0-2.6). These findings suggest that HPV-associated tumors differ molecularly from those arising after heavy tobacco use and that this epigenetic alteration may affect survival in HPV-negative patients already exhibiting a more aggressive disease.

Molecular mechanisms of head and neck cancer

Despite advances in understanding the underlying genetics, squamous cell carcinoma of the head and neck (SCCHN) remains a major health risk and one of the leading causes of mortality in the world. Current standards of treatment have significantly improved long-term survival rates of patients, but second tumors and metastases still remain the most frequent cause of high mortality in SCCHN patients. A better understanding of the underlying genetic mechanisms of SCCHN tumorigenesis will help in developing better diagnostics and, hence, better cures. In this article we will briefly outline the current state of diagnostics and treatment and our understanding of the molecular causes of SCCHN.

Dietary risk factors for squamous cell carcinoma of the upper aerodigestive tract in central and eastern Europe

OBJECTIVE

The incidence of squamous cell carcinoma of upper aerodigestive tract (UADT: oral cavity, pharynx, larynx, and esophagus) has been increasing in central and eastern European countries. We investigated the relationship between diet and UADT cancers in these high risk areas.

METHODS

We used data from hospital-based case-control study of 948 UADT cancer cases and 1,228 controls conducted in Romania, Hungary, Poland, Russia, Slovakia, and Czech Republic. Standardized questionnaire were used to collect information on 23 different food items, along with alcohol and tobacco consumptions. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the UADT cancers after adjusting for center, age, sex, tobacco & alcohol intake, and other food groups.

RESULTS

Consumption of dairy product was negatively associated with selected UADT cancers: larynx (OR: 0.38, CI: 0.23-0.62) and esophagus (OR: 0.55, CI: 0.33-0.93). While consumption of yellow/orange vegetables were inversely associated with oral/pharyngeal and laryngeal cancer (OR: 0.53, CI: 0.35-0.81 and OR: 0.62, CI: 0.38-1.00, respectively), preserved vegetable was positively associated with oral/pharyngeal and laryngeal cancer risk (p (trend) < 0.01 for both).

CONCLUSION

Specific dietary components may play a role in the development of UADT cancers in the high-risk region of central and eastern Europe.

A prospective study of red and processed meat intake in relation to cancer risk

BACKGROUND

Red meat and processed meat have been associated with carcinogenesis at several anatomic sites, but no prospective study has examined meat intake in relation to a range of malignancies. We investigated whether red or processed meat intake increases cancer risk at a variety of sites.

METHODS AND FINDINGS

The National Institutes of Health (NIH)-AARP (formerly the American Association for Retired Persons) Diet and Health Study is a cohort of approximately 500,000 people aged 50-71 y at baseline (1995-1996). Meat intake was estimated from a food frequency questionnaire administered at baseline. Cox proportional hazards regression was used to estimate hazard ratios and 95% confidence intervals within quintiles of red and processed meat intake. During up to 8.2 y of follow-up, 53,396 incident cancers were ascertained. Statistically significant elevated risks (ranging from 20% to 60%) were evident for esophageal, colorectal, liver, and lung cancer, comparing individuals in the highest with those in the lowest quintile of red meat intake. Furthermore, individuals in the highest quintile of processed meat intake had a 20% elevated risk for colorectal and a 16% elevated risk for lung cancer.

CONCLUSIONS

Both red and processed meat intakes were positively associated with cancers of the colorectum and lung; furthermore, red meat intake was associated with an elevated risk for cancers of the esophagus and liver.

Ulcerative lesions of the mouth: an update for the general medical practitioner

Oral ulceration is a common complaint of patients attending out-patient clinics. Because of the diversity in causes of oral ulceration, patients presenting with oral mucosal disease can be challenging to diagnose and manage. Patients with signs or symptoms of oral ulcers are sometimes referred to gastroenterology clinics; however, in most instances the ulcers do not result from gastrointestinal disease. The aim of the present article is to review aspects of the etiology, diagnosis and management of common ulcerative disorders of the oral mucosa. A search in the National Library of Medicine computerized bibliographic database MEDLINE was performed. Selection of publications, extraction of data, and validity assessment were then performed by the authors. Based upon the searched literature, it is concluded that there are several systemic disorders that can present with similar clinical signs and symptoms, and knowledge of each disease is necessary for the clinician to provide proper management.

Current topics in the epidemiology of oral cavity and oropharyngeal cancers

Oral cancer incidence rates rose dramatically during the twentieth century in the United States and Europe, especially among individuals under the age of 60 years. Although influenced by age, sex, and country of origin, incidence trends were most strongly affected by elevated risk among individuals born after approximately 1915. This cohort effect was indicative of strong behavioral influences on oral cancer risk. In this article, associations between oral cancer risk and established behavioral risk factors including alcohol and tobacco use are reviewed. Additionally, possible associations between oral cancer risk and oral hygiene, diet, nutritional status, and sexual behavior as well as the influence of genetic factors on oral cancer risk are considered. Special emphasis is placed on evaluating possible risk differences in individuals above and below the age of 45 and in users and nonusers of alcohol and tobacco.

Assessment of risk factors for oral squamous cell carcinoma in Chidambaram, Southern India: a case-control study

Oral squamous cell carcinoma, the fifth most common cancer worldwide, is a major cause of morbidity and mortality in India. The effect of lifestyle factors, including tobacco chewing, smoking and alcohol drinking, diet and dental care, on the risk of oral cancer was investigated in a case-control study conducted in Rajah Muthiah Dental College and Hospital, Annamalainagar, Annamalai University, Chidambaram, Tamil Nadu, India during the period 1991-2003. The study included 388 oral squamous cell carcinoma cases and an equal number (388) of age and sex-matched controls. All participants were interviewed using a structured questionnaire that contained data on demographic factors, family history of cancer, tobacco habits, use of alcohol, frequency, duration, cessation of these habits, dietary practices and oral hygiene. The data were analysed using multiple logistic regression model. Among people with chewing habits, those who chewed betel quid with tobacco [odds ratio (OR) 3.19, 95% confidence interval (CI): 0.48-2.13] and tobacco alone (OR 2.89) showed a greater risk than controls. Bidi smoking (OR 4.63) and alcohol drinking (OR 1.65) emerged as significant risk factors for oral cancer. These three habits showed increasing risk with increasing frequency and increase in duration of habits. Addition of alcohol to other habits also enhanced the risk for oral cancer. The combination of chewing and smoking together with alcohol drinking showed very high relative risk (OR 11.34). A positive association was observed between non-vegetarian diet, poor oral hygiene and poor dentition with the risk of oral squamous cell carcinoma. The fact that these risk factors are modifiable emphasizes the need for increasing awareness among the general public and policy makers as a first step in the prevention and control of oral squamous cell carcinoma.

CYP1A1, CYP2E1, GSTM1, GSTT1, EPHX1 exons 3 and 4, and NAT2 polymorphisms, smoking, consumption of alcohol and fruit and vegetables and risk of head and neck cancer

PURPOSE

As risk-modifiers of alcohol and tobacco effects, metabolic genes polymorphisms were investigated as susceptibility candidates for squamous cell carcinoma of the head and neck (SCCHN).

METHODS

A total of 210 cases and 245 hospital controls, age and gender matched, were genotyped for CYP1A1, CYP2E1, GSTM1, GSTT1, EPHX1 exons 3 and 4, and NAT2 polymorphisms. A measurement of the biological interaction among two risk factors was estimated by the attributable proportion (AP) due to interaction and its 95% confidence interval (CI).

RESULTS

SCCHN risk was associated with high-levels of alcohol intake [OR = 3.50 (95%CI: 1.93-6.35) and OR = 6.47 (95%CI: 2.92-14.35) for 19-30 g/day and >30 g/day, respectively], cigarette smoking [OR = 3.47 (95%CI: 1.88-6.41) and OR = 7.65 (95%CI: 4.20-13.90) for 1-25 and >25 pack-years of smoking, respectively] and low-fruit and vegetables consumption (OR = 2.45; 95%CI: 1.53-3.92). No differences were observed for the genotypes or haplotypes distributions among cases and controls, and no biological interaction emerged from gene-gene and gene-environment interaction analyses. An attributable proportion (AP) due to biological interaction of 0.65 (95%CI: 0.40-0.90) was detected for heavy drinkers with a low intake of fruit and vegetables, and an AP of 0.40 (95%CI: 0.10-0.72) resulted forever smokers with low fruit and vegetables consumption.

CONCLUSIONS

Even in presence of high alcohol consumption or cigarette smoking, a high intake of fruit and vegetables might prevent the development of around one quarter of SCCHN cases. The lack of interaction between the studied polymorphisms and the environmental exposures suggests that chronic consumption of tobacco and alcohol overwhelm enzyme defences, irrespective of genotype.

Fruit and vegetables in cancer prevention

Our aim was to review the epidemiological literature on possible cancer-preventive effects of the consumption of fruits and vegetables in humans, to quantify the effect of high versus low consumption of fruits and vegetables, and to give an overall assessment of the existing evidence. We based our work on an expert meeting conducted by the International Agency for Research on Cancer in 2003. A qualitative reading and evaluation of relevant articles on the cancer-preventive effect of the consumption of fruits and vegetables was made followed by the calculation of the mean relative risk and range for cohort and case-control studies separately. The possible population-preventable fraction for modifying diet in relation to fruit and vegetable consumption was calculated as well as an overall statement about the degree of evidence for the cancer-preventive effect of fruit and vegetable consumption for each cancer site. There is limited evidence for a cancer-preventive effect of the consumption of fruits and vegetables for cancer of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary (vegetables only), bladder (fruit only), and kidney. There is inadequate evidence for a cancer-preventive effect of the consumption of fruits and vegetables for all other sites. Applying this range of risk difference to the range of prevalence of low intake, the preventable fraction for low fruit and vegetable intake would fall into the range of 5-12%. It is important to recognize that this is only a crude range of estimates and that the proportion of cancers that might be preventable by increasing fruit and vegetable intake may vary beyond this range for specific cancer sites and across different regions of the world.

Clinical implications of human papillomavirus in head and neck cancers

Human papillomavirus (HPV) is now recognized to play a role in the pathogenesis of a subset of head and neck squamous cell carcinomas (HNSCCs), particularly those that arise from the lingual and palatine tonsils within the oropharynx. High-risk HPV16 is identified in the overwhelming majority of HPV-positive tumors, which have molecular-genetic alterations indicative of viral oncogene function. Measures of HPV exposure, including sexual behaviors, seropositivity to HPV16, and oral, high-risk HPV infection, are associated with increased risk for oropharyngeal cancer. HPV infection may be altering the demographics of HNSCC patients, as these patients tend to be younger, nonsmokers, and nondrinkers. There is sufficient evidence to conclude that a diagnosis of HPV-positive HNSCC has significant prognostic implications; these patients have at least half the risk of death from HNSCC when compared with the HPV-negative patient. The HPV etiology of these tumors may have future clinical implications for the diagnosis, therapy, screening, and prevention of HNSCC.