Betel quid and oral cancer: a review

Alkaloids and nitrosamines in betel quid: A biochemical exploration of carcinogenicity

Betel quid contains two major ingredients; Areca catechu and Piper betel, often consumed with slaked lime, tobacco, certain flavouring agents, colouring agents, herbs, and spices according to personal preferences. The areca nut alkaloids (arecoline, arecaidine, guvacine, and guvacoline), and tobacco alkaloids (nicotine, nornicotine) undergo nitrosation during chewing in the oral cavity with the presence of nitrite and thiocyanate and endogenously. Among the nitrosation products generated areca nut-derived nitrosamine (ADNA): 3-(methylnitrosamino) Propionitrile (MNPN) and the two tobacco-specific nitrosamines (TSNAs); N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone) (NNK) are considered Group 1 human carcinogens. The slaked lime increases pH, reactive oxygen species (ROS) generation, and inflammation further lead to oral potentially malignant disorders (OPMD). The juice swallowed results in carcinogenicity, mutagenicity, and toxicity in the gastrointestinal tract including hepatocytic carcinoma, stomach, and colon cancer. Areca nut pre-treatments (sun drying, roasting, boiling, and fermentation) increase the quid metabolism, and reduce the arecoline content and associated risks. We review biochemical carcinogenesis of betel quid ingredients and synergic adverse effects and possible mechanism of carcinogenesis of betel quid in the oral cavity and gastrointestinal tract to understand the implication of polyphenols and alkaloids of areca nut and betel quid on carcinogenic nitrosamine formation under oral, gastric, and intestinal conditions.

Salivary Areca and tobacco alkaloids for bioverification in the Betel Nut Intervention Trial

BACKGROUND

The Betel Nut Intervention Trial (BENIT) is the first known randomized controlled intervention trial designed to help minority Pacific Islanders in Guam and Saipan quit chewing the carcinogenic Areca catechu nut (AN). We report the BENIT's saliva bioverification results against the self-reported chewing status ("quitter" or "chewer") at day 22 follow-up.

MATERIAL AND METHODS

AN-specific (arecoline, arecaidine, guvacoline, and guvacine) and tobacco-specific (nicotine, cotinine, and hydroxycotinine) alkaloids were analyzed in saliva from 176 BENIT participants by an established and sensitive liquid chromatography mass spectrometry-based assay.

RESULTS

The combined four AN alkaloid levels decreased from baseline in quitters (n = 50) and chewers (n = 108) by 32% and 9%, respectively. In quitters, decreases were significant for arecoline (p = 0.044)-the most prominent AN alkaloid, along with arecaidine (p = 0.042) and nicotine (p = 0.011). In chewers, decreases were significant only for hydroxycotinine (p = 0.004). Similar results were obtained when quitters and chewers were stratified by treatment arm.

DISCUSSION

Salivary AN alkaloid levels generally agreed with self-reported chewing status, which suggests the former can be used to verify the latter.

CONCLUSION

Our results can help to objectively evaluate compliance and program effectiveness in AN cessation programs.

Metabolomic Profile of Indonesian Betel Quids

Consumption of areca nut alone, or in the form of betel quid (BQ), has negative health effects and is carcinogenic to humans. Indonesia is one of the largest producers of areca nuts worldwide, yet little is known about the biomolecular composition of Indonesian areca nuts and BQs. We have recently shown that phenolic and alkaloid content of Indonesian BQs exhibits distinct geographical differences. Here, we profiled for the first time the metabolomics of BQ constituents from four regions of Indonesia using non-targeted gas chromatography-mass spectrometry (GC-MS) analysis. In addition to well-known alkaloids, the analysis of small-molecule profiles tentatively identified 92 phytochemicals in BQ. These included mainly benzenoids and terpenes, as well as acids, aldehydes, alcohols, and esters. Safrole, a potentially genotoxic benzenoid, was found abundantly in betel (Piper betle) inflorescence from West Papua and was not detected in areca nut samples from any Indonesian region except West Papua. Terpenes were mostly detected in betel leaves and inflorescence/stem. Areca nut, husk, betel leaf, the inflorescence stem, and BQ mixture expressed distinctive metabolite patterns, and a significant variation in the content and concentration of metabolites was found across different geographical regions. In summary, this was the first metabolomic study of BQs using GC-MS. The results demonstrate that the molecular constituents of BQs vary geographically and suggest that the differential disease-inducing capacity of BQs may reflect their distinct chemical composition.

Geographical heterogeneity in the American Joint committee on Cancer oral cancer staging and prognostic implications

OBJECTIVES

The AJCC 8th edition (AJCC 8) has introduced depth of invasion (DOI) and extranodal extension (ENE) into staging for oral squamous cell carcinoma (OSCC). Although validations have been performed on institutional datasets have shown a good performance, particularly in early OSCC, there have been no studies on diverse patient populations that determine the impact on prognostic heterogeneity.

MATERIALS AND METHODS

Retrospective analysis of 4710 patients with oral squamous cell carcinoma (OSCC) treated with surgery +/- adjuvant therapy in 8 institutions in Australia, North America and Asia. With overall survival (OS) as endpoint, the prognostic performance of AJCC 7th and 8th editions were compared using Akaike Information Criterion (AIC), Bayesian Information Criteria (BIC), Harrell's concordance index (C-index).

RESULTS

When comparing AJCC 8 to AJCC 7, the heterogeneity in prediction of OS increased for T-category and N-category while remaining unchanged for TNM staging, suggesting AJCC 8 increased complexity with no improvement in predictive value. There were significant differences in median DOI and incidence of ENE between geographical regions, resulting in dissimilar rates of stage-migration when adopting AJCC 8.

CONCLUSION

In an attempt to improve prognostic performance, AJCC 8 introduced more variables; however heterogeneity in these results in significant geographical differences in model discrimination and performance. Caution should be applied as this may result in inaccurate and unreliable prognostic predictions that may impact treatment recommendations.

Strengthening antioxidant defense & cardio protection by Piper betle: An in-vitro study

Introduction

The purpose of this research work was to evaluate Piper betle ethyl acetate extract (PBEA) for its free radical scavenging, antioxidant, anti-apoptotic activities and its role in protecting against oxidative cardiac cell injury.

Methods

The Free radical scavenging activity and antioxidant potential of PBEA were evaluated using various non-cellular methods (1,1-Diphenyl-2-picrylhydrazyl, β-carotene bleaching, superoxide anion, hydroxyl radical, hydrogen peroxide_, Reducing power, Total phenolics and Total flavonoids). PBEA was standardized with Eugenol by GC-FID analysis. Furthermore, PBEA was also assessed for its cytotoprotective effect against 100μM H₂O₂ in H9c2 cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Intracellular reactive oxygen species scavenging and anti-apoptoic activity of PBEA was assessed by using 2′, 7′-Dichlorofluorescein diacetate and Annexin- Propidium Iodide, respectively.

Results

PBEA exhibited radical scavenging and antioxidant defense response at different magnitudes of potency. Eugenol, a cardiac protective bioactive molecule in PBEA was found to be 43.43 ± 1.46 mg/g of PBEA extract. Further, pre-incubation of H9c2 cells with 10 μg/ml PBEA for 24 h exhibited remarkable cytoprotective effect against H₂O₂ induced oxidative stress. PBEA at 10 μg/ml dose with 24 h contact with H9c2 cells significantly enhanced the activity of cellular defense system and significantly decreased intracellular ROS (P < 0.001) and apoptosis (P < 0.01) thereby protecting against the cytotoxic effects of H₂O₂.

Conclusion

These outcomes indicated that PBEA could shield against oxidative and apoptotic cardiac cell injury in invitro studies. Thus, PBEA might be a desirable antioxidant of natural origin that has future clinical implications in both health care and food industry.

Analysis of Alkaloids in Areca Nut-Containing Products by Liquid Chromatography-Tandem Mass Spectrometry

Chewing of areca nut in different forms such as betel quid or commercially produced pan masala and gutkha is common practice in the Indian subcontinent and many parts of Asia and is associated with a variety of negative health outcomes, particularly oral and esophageal cancers. Areca nut-specific alkaloids arecoline, arecaidine, guvacoline, and guvacine have been implicated in both the abuse liability and the carcinogenicity of the areca nut. Therefore, variations in the levels of areca alkaloids could potentially contribute to variations in addictive and carcinogenic potential across areca nut-containing products. Here, we developed an accurate and robust liquid chromatography-tandem mass-spectrometry (LC-MS/MS) method for simultaneous quantitation of all four areca alkaloids and applied this method to the analysis of a range of products obtained from India, China, and the United States. The results of the analyses revealed substantial variations in the levels of alkaloids across the tested products, with guvacine being the most abundant (1.39-8.16 mg/g), followed by arecoline (0.64-2.22 mg/g), arecaidine (0.14-1.70 mg/g), and guvacoline (0.17-0.99 mg/g). Substantial differences in the relative contribution of individual alkaloids to the total alkaloid content were also observed among the different products. Our results highlight the need for systematic surveillance of constituent levels in areca nut-containing products and a better understanding of the relationship between the chemical profile and the harmful potential of these products.

Smokeless tobacco and coronary heart disease: a 12-year follow-up study

Background Cigarette smoking has declined whereas the use of smokeless tobacco is increasing. There is an ongoing debate as to whether smokeless tobacco is a recommendable strategy to help smokers to quit. However, very few studies have examined the association between smokeless tobacco, namely snuff, and coronary heart disease, which implies that it has not been possible to provide scientific results for public health policies and clinical guidelines concerning the use of smokeless tobacco.

Design A follow-up study.

Methods A random sample of 3120 healthy men aged 30–74 years was interviewed in 1988 and 1989 and followed up to the year 2000 with regard to coronary heart disease. Cox regression was used to estimate the relative risk of coronary heart disease in six categories of smoking and snuffing habits, after adjustment for established risk factors for coronary heart disease.

Results Smokers, former smokers, and those who combined smoking and snuffing had significantly higher hazard ratios than never-smokers. The very highest hazard ratio was found among individuals combining smoking and snuffing. Daily snuffers had a hazard ratio of 1.62 (95% confidence interval 0.70–3.03) after adjustment for age.

Conclusions Even though the association between daily snuffing and coronary heart disease was non-significant, the hazard ratio was markedly increased. Therefore, smokers should not use smokeless tobacco in order to quit smoking, especially as safer alternatives are available. Further studies in different settings are required to provide scientific results for public health policies and clinical guidelines.

Composition of betel specific chemicals in saliva during betel chewing for the identification of biomarkers

Betel nut chewing causes cancer in humans, including strong associations with head and neck cancer in Guam. In the search for biomarkers of betel chewing we sought to identify chemicals specific for the 3 most commonly consumed betel preparations in Guam: nut ('BN'), nut + Piper betle leaf ('BL'), and betel quid ('BQ') consisting of nut + lime + tobacco + Piper betle leaf. Chemicals were extracted from the chewing material and saliva of subjects chewing these betel preparations. Saliva analysis involved protein precipitation with acetonitrile, dilution with formic acid followed by LCMS analysis. Baseline and chewing saliva levels were compared using t-tests and differences between groups were compared by ANOVA; p < 0.05 indicated significance. Predominant compounds in chewing material were guvacine, arecoline, guvacoline, arecaidine, chavibetol, and nicotine. In chewing saliva we found significant increases from baseline for guvacine (BN, BQ), arecoline (all groups), guvacoline (BN), arecaidine (all groups), nicotine (BQ), and chavibetol (BL, BQ), and significant differences between all groups for total areca-specific alkaloids, total tobacco-specific alkaloids and chavibetol. From this pilot study, we propose the following chemical patterns as biomarkers: areca alkaloids for BN use, areca alkaloids and chavibetol for BL use, and areca alkaloids plus chavibetol and tobacco-specific alkaloids for BQ use.

Antioxidant, Anti-inflammatory, and Chemoprotective Properties of Acacia catechu Heartwood Extracts

Aqueous extracts of Acacia catechu heartwood are rich source of catechin and epicatechin (gallic acid derivatives), with smaller amounts of flavonoids. Extracts have also been prepared with ethyl acetate, ethanol, and methanol, and the properties of these extracts have been studied and are reviewed. Potent antioxidant activity has been well established in both in vitro and in vivo studies. This antioxidant activity is believed to be responsible for the anti-inflammatory, tissue protectant, antineoplastic, and analgesic activities that have been demonstrated and clearly established in animal and cell culture systems. Furthermore, antihyperglycemic, antidiarrheal, antinociceptive, and antipyretic activities have been demonstrated in animal studies. No adverse effects have been observed in animal or human studies or in cell culture systems. In spite of the fact that Acacia products have been used for many years and the general safety of catechins and epicatechins is well documented, few human studies have ever been conducted on the efficacy or safety of A. catechu heartwood extracts. Several studies have shown that a two-ingredient combination product containing A. catechu extract exhibited no adverse effects when administered daily for up to 12 weeks while exhibiting significant anti-inflammatory activity in subjects with osteoarthritis of the knee. There is a need for additional human clinical studies with regard to efficacy and safety.

Panmasala chewing induces deterioration in oral health and its implications in carcinogenesis

ABSTRACT Panmasala containing tobacco was introduced in the Indian market during the 1970s. Panmasala consists of areca nut (betel nut), catechu, lime, cardamom, spices, and unspecified flavoring agents, etc., with tobacco locally known as gutkha or without tobacco (Plain or sada), and consumed abundantly in India and also other parts of the world, predominantly in South East Asian countries. Available studies demonstrate that the habits of chewing panmasala gutkha or plain by students and adolesescents are on the increase, which may lead to deterioration of oral health and other organ systems. Based on the experimental as well as clinical studies available on panmasala as well as on different components of panmasala, this review suggests that it has the potential in causation of various oral diseases such as Oral Sub Mucosis Fibrosis (OSMF) and leucoplakia which may lead to oral cancer. Studies reviewed on these chewing mixtures also reveal that it is likely to be carcinogenic, as tobacco and areca nut have carcinogenic potential and both have encompassing addictive potential leading to dependence on chewing mixture containing areca nut and tobacco. These mixtures might not only lead to cancer but may also affect other organs of the body, including oral hard tissues in the form of dental attrition and sensitivity. There is a need to consider the potential health hazards associated with the habits of these products, especially oral cancer. More research is needed to find out early changes which could be reversible and also intervention measures through education to desist people in indulging in such habits.

Intraosseous verrucous carcinoma arising from an infected dentigerous cyst-A case report

Intraosseous verrucous carcinoma (IOVC) arising from an odontogenic cyst is extremely rare. We report a case of intraosseous verrucous carcinoma in a 74-year-old male who presented with a left mandibular swelling with recurrent pus discharge from gingiva of tooth #35. Panoramic radiography revealed an impacted tooth #34 and a large well-defined, radiolucent lesion surrounding the crown of tooth #34. The clinical diagnosis was an infected dentigerous cyst. Surgical excision of the cyst together with extraction of tooth #34 was performed. Histopathological examination showed proliferation of hyperparakeratotic stratified squamous cyst lining epithelium and down-growth of broad and bulbous epithelial ridges with pushing border invasion into the fibrous cystic wall. A verrucous carcinoma arising from an infected dentigerous cyst was diagnosed. There was no recurrence of the tumor 5 months after surgery.

Head and neck squamous cell carcinoma in chronic areca nut chewing Indian women: Case series and review of literature

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is an important public health problem in India. Several risk factors such as tobacco, human papilloma virus, alcohol, areca nut usage have been extensively studied as causative agents. Though Areca nut chewing is known cause of oral cancer, its association with hypopharynx cancer has not been previously reported. Since areca nut is mostly consumed along with tobacco, it is uncommon to find patients who consume the areca nut alone.

MATERIALS AND METHODS

This is a prospective case series of ten women who presented to us with HNSCC with history of chewing of areca nut alone for several years. We have excluded all those cases where areca nut was consumed along with tobacco in any form. The data were prospectively collected with regard to clinical parameters, duration and frequency of areca nut usage, the socio-economic status and education level.

RESULTS

All ten females had varying degree of submucous fibrosis and coexisting squamous cell carcinoma either in the oral cavity or hypopharynx. Submucous fibrosis was characterized by burning mouth, unhealthy oral mucosa, buried third molars, trismus, poor oral hygiene, etc. The disease presented in an advanced stage in majority of the cases. All patients were unaware of areca nut's deleterious effects.

CONCLUSION

Areca nut chewing is an important risk factor for HNSCC in females. Despite plethora of information, little importance is given to areca nut control in cancer prevention campaigns in India.

Oral Cancer Screening at Workplace in India-One-year Follow-up

Background:

Oral cancer remains the commonest form of cancer and cancer-related deaths among Indian males due to popularity of avoidable risk factors such as tobacco and alcohol use. A workplace oral cancer screening and tobacco cessation study was commenced on World No Tobacco Day 2007 at a chemical industry in rural Maharashtra.

Aims:

The objectives were to screen the employees for oral neoplasia and to correlate it with their tobacco consumption pattern. In addition, the objective was to provide tobacco cessation services at the workplace.

Materials and Methods:

This is an interventional cohort study among 104 employees of a chemical industrial unit in rural Maharashtra. Naked eye examination of the oral cavity was performed for all employees by a doctor irrespective of the tobacco habits at the beginning and at the end of 1 year. In between, the tobacco users were regularly examined during each follow-up.

Statistical analysis used:

Through personal interviews of the participants, data were manually recorded and were transferred to electronic data base. Data analysis was conducted in STATA™ 8.2 on intention to treat basis.

Results and Conclusions:

Among the 104 employees, 50 (48.08%) were current tobacco users at the beginning of the program. Oral precancers were seen exclusively among 20 (40%) tobacco users. After 1 year of workplace tobacco cessation intervention, 80% of oral precancers regressed. This shows that screening of the oral cavity at the workplace is effective when combined with tobacco cessation.

Effect of chewing a single betel-quid on autonomic nervous modulation in healthy young adults

Betel-quid is widely used around the world as a stimulant for the autonomic nervous system. The aim of this study was to assess the effect of betel-quid chewing on autonomic nervous modulation by using spectral heart rate variability (HRV) analysis. Twenty healthy young adults were included in this study. Each subject chewed a single betel-quid containing one betel nut or a piece of chewing-gum for 60 min on different days in random order. Spectral HRV measures were obtained before, and 5, 30 and 60 min after starting to chew betel-quid or gum. Sequential changes in HRV measures were compared between chewing gum and betel-quid. Heart rate was significantly elevated after 5 min chewing betel-quid, but not after chewing gum. The normalized low-frequency power and low-/high-frequency power ratio were elevated after 5 min chewing gum or betel-quid; however, the normalized high-frequency power was reduced after 5 min chewing gum or betel-quid. The percentage changes in total power after 5, 30 and 60 min chewing betel-quid were significantly lower than those after chewing gum. This study confirms that novice chewing of betel-quid modulates autonomic nervous system activity; transiently enhancing sympathetic activity and gradually suppressing vagal activity in healthy young adults.

In vitro effects of arecoline on sperm motility and cyclooxygenase-2 expression

Semen samples were obtained from 30 volunteers who had never consumed betel quid. Swim-up spermatozoa from the 30 seminal samples of non-betel quid chewers and also non-smokers, usually not exposed to passive smoking, were treated in vitro with arecoline at different concentrations to evaluate the action of these drugs on sperm motility. Highly motile sperms were collected and divided into 5 equal fractions. Four fractions were supplemented with various concentrations of arecoline and one as control. The study was carried out at time 0 and +1, +2, +3 and +4 hr of incubation. Sperm cells were also extracted and blotted with COX-2 antibody after arecoline treatment after 4 hr incubation. The sperm motility parameters, i.e., motility, average path velocity, curvilinear velocity, straight-line velocity and linearity, were significantly decreased after arecoline treatment. In vitro, arecoline induces the COX-2 expression of sperm cells in a dose-dependent manner. This is the first report to demonstrate that arecoline may mediate COX-2 expression in human sperms, resulting in inflammation response. This situation may act on the structure responsible for the flagellar motion and cause the reduction of sperm motility.

Effects of arecoline in relaxing human umbilical vessels and inhibiting endothelial cell growth

This study investigated the effects of arecoline, an active ingredient of the areca nut, on the tone of human umbilical arteries and veins and on the eNOS expression and cell proliferation of human umbilical vein endothelial cells (HUVECs). We found that arecoline relaxes the human umbilical artery and vein rings in a concentration-dependent manner; the higher the concentration of arecoline, the greater the relaxation of the rings. However, the relaxation decreases after the endothelium was removed or pretreated with L-NAME, a nitric oxide synthase inhibitor. Moreover, arecoline increases in a dose-dependent way the cGMP levels of human umbilical arteries and veins. In HUVECs, arecoline also increases the eNOS expression. Therefore, the relaxant effects of arecoline on the umbilical artery and vein rings were endothelium-dependent through the NO-cGMP systems. In addition, arecoline at higher doses (100-1000 microM) inhibits endothelial cell proliferation; the exposure toarecoline (100-1000 microM) for 24 and 48 h induces G2/M cell cycle arrest of HUVECs. Our results indicate that arecoline would decrease vascular tone, in part mediated by NO. Higher doses of arecoline inhibit endothelial cell growth, which suggest that long-term use or high doses of areca nut might induce endothelial dysfunction and associated diseases.

Different impact from betel quid, alcohol and cigarette: risk factors for pharyngeal and laryngeal cancer

The risks of betel quid chewing with or without tobacco, alcohol drinking and cigarette smoking have been well explored in the oral cavity but not in the pharynx and larynx. We conducted a case-control study to investigate the association of these three risk factors to cancers of the pharynx and larynx in Taiwan. A total cases of 148 pharyngeal cancer, 128 laryngeal cancer and 255 hospital controls, all men, were recruited. Betel quid chewing was a significant independent risk factor (adjusted odds ratio [aOR] = 7.7; 95% confidence interval [CI] = 4.1-15.0) similar to that of alcohol drinking (aOR = 6.6; 95% CI = 3.5-13.0) for pharyngeal cancer, but not for laryngeal cancer (aOR = 1.3; 95% CI = 0.7-2.5) on which cigarette smoking (aOR = 7.1) exerts a stronger significant independent risk than alcohol drinking (aOR = 3.8). For pharyngeal cancers, chewers who consumed >20 quid/day, chewed with inflorescence in the quid or swallowed the betel quid juice were at higher risks; significant dose-response effects were found in daily quantity of drinking and chewing, and cumulative quantity of drinking. Synergistic effects from the 3 risk factors existed both on the pharynx (aOR = 96.9) and the larynx (aOR = 40.3), and attributed for 93.1% and 92.9% respectively. Our study is the first evidence to show that betel quid chewing without tobacco has different impact on the pharynx (digestive tract) and the larynx (airway), and supports the concept that exposure quantity and direct mucosal contact with the betel quid juice may contribute to carcinogenesis. Our results show an important insight into the impact of betel quid chewing on other sites of the digestive tract other than the oral cavity.

Habitual risk factors for head and neck cancer

Chronic tobacco smoking and alcohol consumption are well-established risk factors for the development of squamous cell carcinoma (SCC) of the head and neck. There are, however, a variety of other habitual and culturally based activities that are less commonly seen in the Western world and that are also risks factors for the development of this type of cancer. In this era of globalization, many of these habits have now crossed borders and appear in various areas throughout the world. This article reviews habitual and social risk factors for cancer of the head and neck, excluding smoking and alcohol consumption. These factors include chewing tobacco and snuff, areca nut in its various forms, Khat leaves, and the drinking of Mate.

EBM RATING

D.

The tumor promoting effect of lime-piper betel quid in JB6 cells

Betel quid chewing is a general behavior in Taiwan, India, southeastern Asian and South Africa. In this study, microculture tetrazolium test (MTT) showed that the extract of lime-piper betel quid (LPB) (1.0-20 mg/ml) was toxic to JB6 cells. Cells exposed of LPB (0.1, 0.5, 1.0 mg/ml) for 7 days resulted in changes in cytomorphology with characteristics of carcinogenesis. With a long-term treatment (approximately 30 days) of low doses of LPB (1, 5, 10 microg/ml), the production of H2O2 and the activity of myeloperoxidase (MPO) and ornithine decarboxylase (ODC) were increased in JB6 cells. Cell cycle analysis showed a decrease in the G1 phase and an accumulation in the S phase 48 h after LPB treatment. When treating with 0.5 mg/ml LPB for 15 days as a promoter, type III foci were formed in the JB6 culture. These results demonstrated the tumor promotional effect of LPB in JB6 cells.

Decline of oropharyngeal cancer in Chiangmai province, Thailand, between 1988 and 1999

A decline of oropharyngeal cancer has already been predicted for Thailand since the early 1960s. To substantiate these predictions it was the purpose of this study to examine trends in the incidence of oropharyngeal cancer in the province of Chiangmai, (1988-1999). Data on cancer incidence were extracted from the annual reports of the Cancer Registry, Cancer Unit, Faculty of Medicine, Chiangmai University, Thailand (1992-1999) and an IARC report on cancer in Thailand (1988-1991). The age-standardized annual incidence per 100000 of oral cancer in males dropped from 3.6 (1988-1991) to 1.2 in 1999 (P for trend 0.0002) and in females from 2.6 (1988-1991) to 1.1 in 1999 (P for trend 0.007). Similar trends in males and females for cancer of the tongue, oropharynx and hypopharynx were seen. The age-standardized annual incidence for cancer of the lip, salivary gland and nasopharyngeal carcinoma remained unchanged. Changes of traditional oral habits such as betel quid chewing and smoking of traditional cigars seem to have resulted in a marked decrease of oral cancer in both men and women in the recent past.

Susceptibility and biomarker knowledge for improvement of environmental health

At the international level, environmental health problems are usually most serious in countries that have the least resources to deal with the problems. Therefore, international efforts have been initiated to achieve equitable environmental health globally. One approach is to conduct international collaborative studies. This approach has been successful in the building of scientific infrastructure in these countries so that they can address their own environmental health concerns and to sustain the environmental health programs. Using liver and oral cancers as models for discussion, examples of success in the identification of etiology and the mechanisms for the diseases are provided. For example, biomarkers are used to provide early warning signals for the disease. In addition, the application of the collected information for developing disease prevention and intervention programs is presented. Expertise in genetic susceptibility is used to provide a more precise understanding of the cancer process. With the precise knowledge, the information can potentially be used to screen for high-risk individuals and to develop "designer" intervention procedures against specific biochemical defects. Success in disease prevention is dependent upon multidisciplinary collaborations at the local and international levels.

Smokeless tobacco and cardiovascular disease

Various forms of smokeless tobacco (mainly snuff and chewing tobacco) cause an immediate increase in heart rate and blood pressure, but regular users of smokeless tobacco do not have permanent changes of heart rate or blood pressure when not exposed to tobacco. Cardiac output during workload and maximal working capacity are unaffected. Users of smokeless tobacco usually do not have the biochemical stigmata that regular smokers have. Thus, the scientific literature suggests that they are similar to non-tobacco users in terms of levels of hemoglobin/hematocrit, leukocytes, antioxidant vitamins, fibrinogen, components of the fibrinolytic system, C-reactive protein, and thromboxane A2 production. Two studies have found that snuff users, as opposed to smokers, do not have increased intima-media thickness or atherosclerotic lesions when investigated by ultrasound. Results on the risk for myocardial infarction have provided conflicting evidence, 2 case-control studies showing the same risks as in non-tobacco users and one cohort study showing an increased risk for cardiovascular death. In all, the use of smokeless tobacco (with snuff being the most studied variant) involves a much lower risk for adverse cardiovascular effects than smoking does. Whether or not the apparent risk reduction is a useful strategy to help inveterate smokers to quit is a matter of debate, as are the public health effects of a high prevalence of snuff use in some populations.

Modulation of platelet aggregation by areca nut and betel leaf ingredients: roles of reactive oxygen species and cyclooxygenase

There are 2 to 6 billion betel quid (BQ) chewers in the world. Areca nut (AN), a BQ component, modulates arachidonic acid (AA) metabolism, which is crucial for platelet function. AN extract (1 and 2 mg/ml) stimulated rabbit platelet aggregation, with induction of thromboxane B2 (TXB2) production. Contrastingly, Piper betle leaf (PBL) extract inhibited AA-, collagen-, and U46619-induced platelet aggregation, and TXB2 and prostaglandin-D2 (PGD2) production. PBL extract also inhibited platelet TXB2 and PGD2 production triggered by thrombin, platelet activating factor (PAF), and adenosine diphosphate (ADP), whereas little effect on platelet aggregation was noted. Moreover, PBL is a scavenger of O2(*-) and *OH, and inhibits xanthine oxidase activity and the (*)OH-induced PUC18 DNA breaks. Deferoxamine, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) and neomycin prevented AN-induced platelet aggregation and TXB2 production. Indomethacin, genistein, and PBL extract inhibited only TXB2 production, but not platelet aggregation. Catalase, superoxide dismutase, and dimethylthiourea (DMT) showed little effect on AN-induced platelet aggregation, whereas catalase and DMT inhibited the AN-induced TXB2 production. These results suggest that AN-induced platelet aggregation is associated with iron-mediated reactive oxygen species production, calcium mobilization, phospholipase C activation, and TXB2 production. PBL inhibited platelet aggregation via both its antioxidative effects and effects on TXB2 and PGD2 production. Effects of AN and PBL on platelet aggregation and AA metabolism is crucial for platelet activation in the oral mucosa and cardiovascular system in BQ chewers.

Global epidemiology of areca nut usage

A substantial proportion of the world's population is engaged in chewing areca nut and the habit is endemic throughout the Indian subcontinent, large parts of south Asia and Melanesia. A large variety of ingredients, including tobacco, may be used along with areca nut constituting a betel quid. The composition and method of chewing can vary widely from country to country and these population variations are described in this review. Some populations are known to use areca nut without tobacco providing good opportunities to further research the carcinogenecity of areca nut. Some interesting trends on chewing patterns have emerged from recent data, suggesting a decline in the habit in some countries such as Thailand while the prevalence of areca nut use is rising in India and Taiwan.

Role of areca nut in betel quid-associated chemical carcinogenesis: current awareness and future perspectives

Betel quid (BQ)-chewing is a popular oral habit with potential links to the occurrence of oral cancer. Many of the literature-based studies reveal that areca nut (AN) extract may demonstrate mutagenic and genotoxic effects, in addition to inducing preneoplastic as well as neoplastic lesions in experimental animals. Areca nut should, thus, be highly suspected as a human carcinogen. Toxicity studies relating to AN-contained polyphenols and tannins are not conclusive, with both carcinogenic and anti-carcinogenic effects being reported. The mutagenicity and genotoxicity of areca alkaloids has been detected by many short-term assays. However, their genotoxicity to oral fibroblasts and keratinocytes, the target cells of BQ, has not been identified. It would thus appear that AN toxicity is not completely due to its polyphenol, tannin and alkaloid content. The single agent which is responsible for AN carcinogenicity awaits further clarification. Reactive oxygen species produced during auto-oxidation of AN polyphenols in the BQ-chewer's saliva, are crucial in the initiation and promotion of oral cancer. Nitrosation of areca alkaloids also produces AN-specific nitrosamines, that have been demonstrated to be mutagenic, genotoxic and are capable of inducing tumors in experimental animals. Arecaidine and AN extract are further suggested to be tumor promoters. Antioxidants such as glutathione and N-acetyl-L-cysteine can potentially prevent such AN-elicited cytotoxicity. Further studies are needed to delineate the metabolism of AN ingredient and their roles in the multi-step chemical carcinogenesis, in order to enhance the success of the future chemoprevention of oral cancer and oral submucous fibrosis.

Synergistic effects of peroxynitrite on arecoline-induced cytotoxicity in human buccal mucosal fibroblasts

Epidemiological studies have demonstrated a clear association between betel nut chewing and an increased risk for oral mucosal lesions. Arecoline, the most abundant betel alkaloid, is considered the most important etiologic factor in betel nuts. In addition, most betel nut chewers are also smokers. In order to elucidate the potential toxicological implications of interactions of arecoline and peroxynitrite (a reaction product of cigarette smoking), cell viability, and cellular levels of glutathione (GSH) were investigated, using cultured human buccal mucosal fibroblasts. At a concentration higher than 0.8 mM, arecoline was cytotoxic to buccal mucosal fibroblasts in a concentration- and time-dependent manner. Arecoline also depleted intracellular GSH in a dose-dependent manner (P<0.05). The addition of extracellular peroxynitrite acted as a synergistic effect on the arecoline-induced cytotoxicity (P<0.05). Furthermore, at a concentration of 0.8 mM, arecoline depleted intracellular GSH by about 42%, while 2 mM peroxynitrite enhanced the arecoline-depleted GSH level further to 86% as compared with the control. During GSH depletion, arecoline may render the human buccal mucosal fibroblasts more vulnerable to other reactive agents within cigarette smoking. Taken together, we suggest that people who combine the habits of betel nut chewing with cigarette smoking could be more susceptible to oral mucosal damage than betel quid chewing alone.

Alcohol, tobacco and paan use and understanding of oral cancer risk among Asian males in Leicester

OBJECTIVES

To determine use of alcohol, tobacco and paan among males from the various Asian communities in Leicester; and assess their knowledge and attitudes towards oral cancer risk factors and prevention. Also, to determine any differences regarding habits and attitudes between first and second generation Asians.

DESIGN

Volunteers completed a confidential, bilingual questionnaire regarding alcohol, tobacco and paan use and also knowledge about oral cancer risk factors and preventive measures.

SETTING

Participants were recruited from sources that included GPs' surgeries, sixth form colleges and places of worship.

SUBJECTS

Asian males, i.e. those of Indian, Pakistani, Bangladeshi or Sri Lankan origin; over the age of 16 years and resident in Leicester.

MAIN OUTCOME MEASURES

Quantitative figures were obtained from the questionnaires as to the frequency of alcohol, tobacco and paan use and responses regarding oral cancer knowledge, risk factors and preventive measures.

RESULTS

The principal Asian community groups in Leicester were Hindu, Sikh, Muslim and Jain. Significant differences were found in males from these groups with regards to habits and oral cancer awareness. Muslim males use tobacco and paan more than the other groups but avoid alcohol. Sikh males drink more alcohol (especially spirits) than the other groups but their use of tobacco and paan is low. Habits of Hindu and Jain males are variable. However, approximately 10% of both 1st and 2nd generation Hindu males combine all three habits of alcohol, tobacco and paan; and are thus considered to be at high risk of developing oral cancer. Seven percent of 1st generation Hindu males were found to chew paans containing tobacco which are strongly associated with oral cancer. More 2nd generation Jains drank alcohol than the 1st generation, and a greater proportion of Hindu, Sikh and Jain 2nd generation males drink spirits than their older counterparts. Knowledge of oral cancer risk factors and preventive measures were variable, the lowest level of knowledge being among the 1st generation Sikh group. Few volunteers realised the risk of alcohol drinking in the aetiology of oral cancer.

CONCLUSION

The 'Asian' community in Leicester is not homogeneous, but consists of distinct community groups; each with their own cultural beliefs, habits and attitudes. Knowledge of these differences can be used to provide appropriate health education programmes suitably targeted to reduce the use of the known risk factors for oral cancer.

Chemopreventive effect of Ocimum sanctum on DMBA-induced hamster buccal pouch carcinogenesis

Ocimum sanctum L., a plant having multi-medicinal properties, has been investigated for its chemopreventive activity against 7,12-dimethylbenz (a) anthracene (DMBA)-induced hamster buccal pouch carcinogenesis. O. sanctum, in the form of fresh leaf paste, aqueous extract and ethanolic extract were topically applied and the extracts were orally administered to buccal pouch mucosa of animals exposed to 0.5% of DMBA. Incidence of papillomas and squamous cell carcinomas were significantly reduced, and increased the survival rate in the topically applied leaf paste and orally administered extracts to animals. Among them, the orally administered aqueous extract showed profound effect than the other two forms. Histopathological observations made on the mucosa confirmed these findings. Further fluorescent spectral studies at 405 nm excitation on the mucosa of control, DMBA and extracts orally administered experimental animals showed a prominent maxima at 430 nm for control, 628 nm for DMBA induced carcinomas while aqueous and ethanolic extracts administered animals showed at 486 nm and 488 nm, respectively. The fluorescent intensity at 630 nm (FI630 nm) was significantly reduced and the ratio of fluorescent intensities at 520 nm and 630 nm (FI520 nm/630 nm) were significantly increased in orally administered extracts compared to DMBA treated animals. These observations suggest that the orally administered extract of O. sanctum may have the ability to prevent the early events of carcinogenesis.

Oral cancer in the UK: to screen or not to screen

Although oral squamous cell carcinoma accounts for only a small proportion of malignant neoplasms in the UK, oral cancer incidence and mortality rates have been rising in recent years. The natural history of oral cancer is not adequately understood at present and there is very little information about the epidemiology of precancerous lesions in the UK. There are also insufficient data to provide firm evidence that the percentage of cases arising de novo is greater in the UK and the Western world as compared to the Indian subcontinent. Screening for oral cancer by visual examination is simple, inexpensive and causes little discomfort; however, there is no evidence for the effectiveness of screening for oral cancer either in reducing mortality from the disease or in reducing the incidence of invasive disease by detection and treatment of precancerous lesions. There is currently insufficient evidence to recommend population screening for oral cancer in the UK. Measures aimed at primary prevention of the disease may be a more feasible method of disease control at present.

pRb and p16 protein alterations in human oral tumorigenesis

Cyclin dependent kinase inhibitor 2/multiple tumour suppressor gene 1 (CDKN2/MTS1) and retinoblastoma (Rb) tumour suppressor genes play important roles in the regulation of the cell cycle. The protein products of these genes p16INK4 (p16) and pRb, respectively, like p53 protein inhibit progression from G1 to S phase. p16 exerts its function through inhibition of CDK4-mediated phosphorylation of pRb. The pRb/p16 pathway is a critical target for molecular aberration at the G1-S checkpoint in a wide range of primary human tumours. The expression of p16 and pRb proteins was analyzed by immunohistochemistry in 35 cases of oral squamous cell carcinomas (SCCs), 22 cases of premalignant oral lesions and 30 normal oral tissues. Lack of pRb expression was observed in 23/35 (66%) oral SCCs and 14/22 (64%) premalignant lesions. Lack of p16 expression was observed in 22/35 (63%) oral SCCs and 13/22 (59%) premalignant lesions. Weak p16 and pRb immunoreactivities were observed in normal oral mucosal epithelium. The status of p16 and pRb was correlated with clinicopathological characteristics of the patients. Alteration in p16 expression showed significant correlation with tumour staging and progression (P = 0.024). Alteration in pRb/p16 expression correlated with heavy consumption of betel and tobacco. Our results suggest that alterations in the p16/pRb pathway are early events in oral tumorigenesis and may be involved in the development of betel- and tobacco-related oral malignancies.