Evaluation of risk factors in smokeless tobacco-associated oral lesions

Oral Potentially Malignant Disorders (OPMD): What is the clinical utility of dysplasia grade?

INTRODUCTION

Oral epithelial dysplasia is considered a potential histologic precursor of subsequent squamous cell cancer. As standard clinical practice, pathologists grade dysplasia to assess risk for progression to malignancy. Except for the most advanced grade, severe dysplasia, dysplasia grading has failed to correlate well with the risk to develop invasive cancer. The questions of what process dysplasia grading best represents and what clinical utility dysplasia grading may have are explored.

AREAS COVERED

This narrative review is based on PubMed search with emphasis on papers since 2010. Epithelial dysplasia as a precursor lesion of cancer and dysplasia grading as a risk assessment tool for progression to cancer are discussed. The close clinical association of dysplasia with known carcinogens, alcohol, and tobacco products is presented.

EXPERT OPINION

Oral epithelial dysplasia is often, associated with prolonged exposure to tobacco and alcohol products. With reduction of carcinogen exposure, dysplasia is known to regress in some cases. It is proposed that histologic dysplasia grade together with macroscopic images of dysplastic clinical lesions be used as an educational tool to incentivize patients to reduce their known carcinogen exposure. This strategy has the potential to reduce lesion progression thereby reducing the disease burden of oral cancer.

Cytological Changes in Normal Oral Mucosa of Individuals with Tobacco Habits: A Cytomorphometric Study

INTRODUCTION

Oral cancer is one of the six most common cancers in the world, and globally more than 50% of head and neck cancers occur in Asia, remarkably in India. Overall, 200,000 cases of head and neck cancers occur each year in India, among which 80,000 are oral cancers. Epidemiological and clinical studies suggest a causative role of tobacco use in the evolution of oral potentially malignant and malignant disorders.

AIMS AND OBJECTIVES

The aim of the study is to evaluate independently and compare the cytological effects of smoking, tobacco chewing, and smoking in conjunction with tobacco chewing on oral mucosa by cytomorphometric analysis.

MATERIALS AND METHODS

The study included a total of 120 individuals subdivided into four groups, each group with 30 individuals. Group I was tobacco smokers, group II tobacco chewers, and group III both tobacco smokers and chewers. Group IV comprised 30 individuals without tobacco habit. Smears were prepared from buccal mucosa of both the study and control groups using a cytobrush and stained using Papanicolaou staining. The cells were quantified using image analysis software.

RESULTS

The results of the study showed alterations in the nuclear and cellular parameters in the study groups when compared with control groups and were statistically significant (p < 0.05).

CONCLUSION

The present study explains the significance of early identification of cellular changes in individuals with tobacco habits who require early intercession even without any visible oral mucosal changes. The study emphasizes that exfoliative cytology and cytomorphometry aid as a valuable tool to evaluate the effect of tobacco on oral mucosa.

CLINICAL SIGNIFICANCE

Simple noninvasive techniques like exfoliative cytology can be employed as a chairside technique and in mass screening programs for identification of cellular changes in oral mucosa of individuals with tobacco habits. Thereby, it can be used as an early diagnostic tool for identification of potentially cancerous and cancerous lesions.

Integrated oral, mental and sexual health management for adolescents: a call for professional collaboration

BACKGROUND

Globally, young people account for 15.5% of the total global disability-adjusted life-years burden for all age groups. They face mental health, nutritional problems, accidental and intentional injuries, sexual and reproductive health problems, and substance abuse. These health challenges have effects on their oral health. This paper discusses the oral health problems adolescents face and suggests approaches for providing integrated oral and general health care for adolescents.

DISCUSSION

Oral health issues linked with adolescent health concerns include: malocclusion and esthetic concerns linked with mental health status; oral and maxillofacial injuries linked with accidental and intentional injuries; oral manifestations of sexually transmitted infections; oral leukoplakia and oral cancers linked with alcohol, tobacco and psychoactive substance abuse; and oral manifestations of anemia resulting from nutritional problems. Training oral health care providers on adolescent health and care could promote prompt diagnosis, management and prevention of complications associated with major health challenges affecting adolescents.

CONCLUSION

Adolescent oral health care needs focused attention: as a possible route for early diagnosis and management of general health problems and for promoting adolescent oral health care. Oral health care should be integrated into adolescent friendly services and oral health care providers should learn how to handle adolescents' health needs.

Low resource screening method of pre-cancerous lesions and its reversal by Triphala in teen-age Indian population

BACKGROUND

Cancer screening is the main weapon for early detection at a pre-invasive or premalignant stage. It has been reported that over 12 million people use some form of tobacco, which is one of the high risk factors and has hence become an alarming world-wide problem.

AIM

To evaluate the effective diagnostic screening of disease in its early stage by inexpensive method and also to evaluate the effect of indigenous mouthrinse on reversal of pre-cancerous lesions.

MATERIALS AND METHODS

The screening for teenagers belonging to low socio-economic status was carried out. Suspected subjects were evaluated for the reversal of the lesions by use of Ayurvedic preparation as a mouthwash. From 13 to19 years working-child population of North India was selected for the study. Screening was performed by new method-visual inspection with acetic acid. The positive subjects were further investigated by pap smear and biopsy was done as a confirmatory histopathological report. In second phase, the subjects showing positive lesions were advised indigenous anti-cancer mouth rinse and its effect was evaluated after 6 month and 9 month of prescribing the rinse.

RESULTS

The total 1095 children were screened (831 boys and 264 girls). Out of total 34 teenager boys were diagnosed, as acetowhite positive lesion. All the acetowhite positive lesions were found exclusively in males. Histological findings after 9 month use of Triphala mouth rinse revealed no changes in cells in 23 (85.2%), hyperkeratinization in 2 (7.4%), hyperkeratinization and spongiosis was evident in 1 (3.7%), mild pleomorphism in 1 (3.7%) patient. Comparative evaluation from 0-9 month showed statistically highly significant test (P < 0.01).

CONCLUSION

Use of different forms of tobacco and betel nut showed convincing relationship between developments of oral pre-cancerous lesions. Triphala was found to have great potential for reversal of these lesions.

[Smokeless tobacco]

Use of smokeless tobacco (ST) (chewing tobacco and snuff) can lead to a number of consequences detrimental to health. ST rapidly delivers high doses of nicotine, which can lead to dependence and is also a source of carcinogenic nitrosamines. Changes usually develop in the mouth area where the ST is most often placed. Non-malignant oral lesions include leuko-oedema, hyperkeratotic lesions of the oral mucosa and localised periodontal disease. Oral premalignant lesions are leukoplakia, erythroplakia, submucosal fibrosis and lichen planus. Betel chewing, with or without tobacco, may increase the incidence of oral cancer. There is conflicting evidence with regard to snuff users about the risk of oral and gastro-oesophageal cancer. ST use is a risk factor for pancreatic cancer and may increase the risk of fatal myocardial infarction and ischemic stroke. During pregnancy, ST is associated with an increase in pre-eclampsia, preterm delivery and stillbirth. Nicotine replacement therapy and bupropion reduce withdrawal symptoms and tobacco craving during ST cessation. However, they have not been shown to help long-term abstinence. Information concerning the potential hazards of ST products should be incorporated into educational programmes to discourage its use and to help users to quit. Smokeless tobacco is not recommended to help smoking cessation.

Dental practitioner's knowledge, opinions and methods of management of oral premalignancy and malignancy

OBJECTIVES

The present study outlines the results of a pilot study to determine the knowledge and awareness of a cohort of dentists in United Arab Emirates (UAE) regarding aetiology, clinical features and appropriate early management of oral premalignant and malignant lesions.

MATERIALS AND METHODS

A self-administered questionnaire was constructed and posted to 300 UAE Dental Practitoners (DPs), selected randomly from the register of Emirates Dental Association. The present report details the responses of this cohort.

RESULTS

182 questionnaires were completed and returned (response rate 60.6%). One hundred and twenty-seven (69.8%) of the responding dentists were male and the median age of the DPs was 40 years (range 24-75 years). The majority (84%) practised or had practised in or around Dubai and Sharjah, 75% had graduated from a dental school after 1980. Eighty-two respondents (45.0%) had attended specific courses on premalignant or malignant oral lesions. During their undergraduate training 70% of DPs had witnessed more than 10 patients with oral SCC. Only 60.4% of respondents indicated that the tobacco and alcohol use were the principle causes of oral SCC while 19.7% suggested that HIV disease was a risk factor for oral SCC. 29% of DPs routinely recorded the tobacco or alcohol use of their patients and only 3.8% offered advice to patients regarding modification of these habits. Eight-three percent of the respondents suggested that clinical screening was an effective means of reducing the frequency of premalignant and malignant oral lesions.

CONCLUSIONS

In view of the gradual rise in oral malignancy worldwide there is an increased need for DPs to be able to recognize the signs and symptoms of oral malignancy and premalignancy, provide appropriate preventive advice and be aware of the appropriate early management of patients with such oral lesions.

Meta-analysis of the relation between European and American smokeless tobacco and oral cancer

BACKGROUND

Smokeless tobacco is often referred to as a major contributor to oral cancer. In some regions, especially Southeast Asia, the risk is difficult to quantify due to the variety of products, compositions (including non-tobacco ingredients) and usage practices involved. In Western populations, the evidence of an increased risk in smokeless tobacco users seems unclear, previous reviews having reached somewhat differing conclusions. We report a detailed quantitative review of the evidence in American and European smokeless tobacco users, and compare our findings with previous reviews and meta-analyses.

METHODS

Following literature review a meta-analysis was conducted of 32 epidemiological studies published between 1920 and 2005 including tests for homogeneity and publication bias.

RESULTS

Based on 38 heterogeneous study-specific estimates of the odds ratio or relative risk for smokeless tobacco use, the random-effects estimate was 1.87 (95% confidence interval 1.40-2.48). The increase was mainly evident in studies conducted before 1980. No increase was seen in studies in Scandinavia. Restricting attention to the seven estimates adjusted for smoking and alcohol eliminated both heterogeneity and excess risk (1.02; 0.82-1.28). Estimates also varied by sex (higher in females) and by study design (higher in case-control studies with hospital controls) but more clearly in studies where estimates were unadjusted, even for age. The pattern of estimates suggests some publication bias. Based on limited data specific to never smokers, the random-effects estimate was 1.94 (0.88-4.28), the eight individual estimates being heterogeneous and based on few exposed cases.

CONCLUSION

Smokeless tobacco, as used in America or Europe, carries at most a minor increased risk of oral cancer. However, elevated risks in specific populations or from specific products cannot definitely be excluded.

Self-awareness of premalignant oral lesions among veterans attending six U.S. Veterans Affairs Medical Centers

Early identification is key to reducing the morbidity and mortality of oropharyngeal cancer. This study identified factors associated with self-awareness among patients newly diagnosed with a premalignant oral lesion. Data describing sociodemographics, medical/dental histories, tobacco/alcohol use and oral health were obtained by questionnaire and clinical examination of 73 veterans at six U.S. Veterans Affairs Medical Centers. Lesion types included homogenous and non-homogenous leukoplakia, smokeless tobacco lesion (STL), papilloma, lichen planus and erythroplakia. Prior to diagnosis, 29 subjects (39.7%) were unaware of their lesion. In bivariate analyses, lesion self-awareness was associated with anatomic location, multifocal/generalized appearance, pain, oral sores, and cigar use (p<0.05). Awareness varied with lesion diagnosis and was more likely with STL and less likely with homogenous leukoplakia (p<0.05). In multivariate analyses, awareness was predicted by the presence of a lesion on easily visible mucosa (adjusted odds ratio, OR=11.2) and a history of mouth sores (OR= 11.2). These findings identified marked variations in patient self-awareness of oral premalignant conditions.

Prospective study of vitamins C, E, and A and carotenoids and risk of oral premalignant lesions in men

Case-control studies indicate that vitamins C, E, A and carotenoids decrease risk of oral premalignant lesions (OPLs) and oral cancer, but clinical trials have failed to find protective effects of beta-carotene and suggest that vitamin E may increase risk. The authors prospectively evaluated the association between intake of vitamins C, E, A and carotenoids and incidence of OPL. Participants were 42,340 men in the Health Professionals Follow-up Study who provided information on supplement use and diet every 2-4 years by food frequency questionnaire. The authors confirmed 207 clinically or histopathologically diagnosed OPL events occurring between 1986 and 2002 by medical record review. Multivariate-adjusted relative risks (RR) of OPL were calculated with proportional hazards models. Total intake of vitamin C, vitamin A or carotenoids was not significantly associated with OPL risk. Dietary vitamin C was significantly associated with reduced risk (quintile 5 vs. 1, RR = 0.52, 95% CI 0.31-0.85, p(trend) = 0.04), but no association with supplemental vitamin C was observed. Inverse associations were apparent for beta-cryptoxanthin and alpha-carotene intake. No clear relationship emerged with beta-carotene, lycopene or lutein/zeaxanthin. Vitamin E was associated with increased risk (quintile 5 vs. 1, RR = 1.86, 95% CI 1.06-3.19), particularly among current smokers and with supplemental intake (current-smokers, supplement dose tertile 3 vs. 1, RR = 3.07, 95% CI 1.28-7.34, p(trend) = 0.01). For current smokers, beta-carotene also increased risk. Vitamin C from dietary sources, but not supplements, was associated with a reduced risk of OPL. The observed increased risk for current smokers with high vitamin E or beta-carotene intake should be explored further.

Oral Mucosal Conditions and Risk Factors among Elderly in a Turkish School of Dentistry

BACKGROUND

Prevalence studies are important to determine the oral health status and treatment needs of elderly people. Our aim was to obtain data for the prevalence of oral mucosal conditions (OMC) in a Turkish elderly sample and to compare our results with different geographic regions.

OBJECTIVE

The purpose of this clinical-based study was to determine the prevalence of OMC and associated risk factors in a clinical-based Turkish elderly sample.

METHODS

The study sample consisted of 700 patients >60 years old. The clinical examination of patients was performed by both authors. All participants were questioned about their general health status, medication use, oral hygiene habits, tobacco or alcohol use, use of dentures, and the length of denture use. Chi2 Pearson's test with Fisher's exact probability test was used to analyze the data. Logistic regression models were used to assess the influence of independent variables; odds ratios were calculated with 95% confidence intervals. Statistical significance was defined as p <0.05.

RESULTS

OMC were recorded in 40.7% of the study sample. The logistic regression model revealed that male gender, length of denture use, smoking habit, and being a former smoker increased the probability of having an OMC. Smoking habit also increased the risk of having leukoplakia. The denture-related lesions accounted for 36.4% with the length of denture use and diabetes mellitus being significant risk factors for denture stomatitis and denture hyperplasia. The model for traumatic ulcer included medication use as a significant risk factor.

CONCLUSIONS

Our results regarding an elderly Turkish sample support the studies of other populations where the prevalence of OMC was related to length of denture use, smoking, and gender. We also observed some important associations between denture-related lesions, systemic diseases, and medication use which require further investigation.

Prospective study of fruits and vegetables and risk of oral premalignant lesions in men

The authors prospectively evaluated fruit and vegetable consumption and the incidence of oral premalignant lesions among 42,311 US men in the Health Professionals Follow-up Study. Diet was assessed every 4 years by food frequency questionnaires. The authors confirmed 207 cases of clinically or histopathologically diagnosed oral premalignant lesions occurring between 1986 and 2002. Multivariate-adjusted relative risks were calculated from proportional hazards models. Significant inverse associations were observed with citrus fruits, citrus fruit juice, and vitamin-C-rich fruits and vegetables, indicating 30-40% lower risks with greater intakes (e.g., citrus fruit juice quintile 5 vs. quintile 1 relative risk = 0.65, 95% confidence interval: 0.42, 0.99). Inverse associations with fruits did not vary by smoking status and were stronger in analyses of baseline consumption, with a 10-year lag time to disease follow-up (quintile 5 vs. quintile 1 relative risk = 0.41, 95% confidence interval: 0.20, 0.82; p = 0.01). No associations were observed with total vegetables or with beta-carotene-rich or lycopene-rich fruits and vegetables. For current smokers, green leafy vegetables (ptrend = 0.05) and beta-carotene-rich fruits and vegetables (ptrend = 0.02) showed significant linear trends of increased risk (one additional serving/day relative risk = 1.7). The risk of oral premalignant lesions was significantly reduced with higher consumption of fruits, particularly citrus fruits and juices, while no consistent associations were apparent for vegetables.

Smokeless tobacco (snuff) use and periodontal bone loss

OBJECTIVE

The aim of the present cross-sectional study was to investigate a possible association between the use of Swedish moist snuff and periodontal bone loss.

MATERIAL AND METHODS

The study was carried out on 84 apparently healthy men in the age range 26-54 years, 25 current snuff users, 21 former snuff users, and 38 never-users. The periodontal bone height was evaluated from bitewing radiographs measuring the distance from the cement-enamel junction (CEJ) to the periodontal bone crest (PBC) at pre-molars and molars in each quadrant of the dentition.

RESULTS

The mean (95% confidence interval (95% CI)) CEJ-PBC distance was 1.00 (0.87-1.13), 1.12 (0.97-1.26), and 1.06 (0.95-1.16) mm for current users, former users, and never-users, respectively. The association between snuff use and bone height level controlling for age was not statistically significant (anovaF = 0.3, p > 0.05). There was, further, no statistically significant difference between light and heavy exposure users controlling for age (anovaF = 1.0, p > 0.05).

CONCLUSION

Our observations suggest that the use of Swedish moist snuff is not associated with periodontal bone loss.

Prospective Study of Alcohol Consumption and Risk of Oral Premalignant Lesions in Men

Recent case-control studies indicate that alcohol increases the risk of oral premalignant lesions (OPL) among tobacco users, but the independent association between alcohol and OPL remains unclear. We prospectively evaluated the association between alcohol consumption and the incidence of OPL. Participants were 41,458 men in the Health Professionals Follow-up Study. Alcohol consumption was assessed every 4 years using validated food frequency questionnaires. We confirmed clinically or histopathologically diagnosed OPL events occurring between 1986 and 2002 by medical record review (193 cases). Multivariate-adjusted relative risks of OPL were calculated from Cox proportional hazards models. With detailed control for tobacco and other variables, multivariate relative risks (95% confidence intervals) were 1.7 (0.9-3.2) for drinkers of 0.1 to 14.9 g/d, 2.9 (1.5-5.6) for 15 to 29.9 g/d, and 2.5 (1.3-5.1) for > or =30 g/d, compared with nondrinkers. Approximately one additional drink per day (12.5 g) was associated with a 22% increase in risk (P < 0.001). The associations did not vary by beverage type, frequency, or consumption with meals. Results were similar when restricted to cases of oral epithelial dysplasia. Alcohol increased OPL risk in never-users of tobacco as well as in past or current users. An interaction between alcohol and tobacco was apparent by their more-than-additive joint effects. Alcohol is an independent risk factor for OPL, regardless of beverage type or drinking pattern. Recommendations to reduce alcohol intake have the potential to reduce incidence of OPL in nonsmokers and smokers alike.

Association between different alcoholic beverages and leukoplakia among non- to moderate-drinking adults: A matched case–control study

While heavy drinking is a risk factor for oral leukoplakia, the effects of moderate drinking and of different alcoholic beverages are unclear and were investigated in this case-control study. 187 leukoplakia patients, aged 40-65 years, who were not heavy drinkers and did not change their drinking/smoking habits over the last decade, were age/gender matched to 187 controls. The effect of regular, moderate, overall alcohol, beer, wine, spirit drinking, adjusted for the effects of heavy smoking and other important co-variables, were assessed using conditional logistic regression analysis. Overall alcohol (OR, 0.22), wine (OR, 0.20), spirits (OR, 2.93) were significantly associated to leukoplakia. A statistically significant interaction wine/heavy smoking was also found. Such different effects could be explained by the ethanol antagonising potential of other drink components, such as polyphenols, abundant in red wine and scarce in spirits. Among heavy smokers, the preventive effect of wine was more than multiplicative.

Risk factors for oral soft tissue lesions in an adult Spanish population

OBJECTIVES

The aims of this study were (i) to determine the prevalence of oral lesions in adults over 30 years old in the city of Oviedo (Spain), and (ii) to analyze the relationship between the prevalence of oral lesions, toxic habits (tobacco and alcohol) and denture wearers in these patients.

METHODS

A representative sample of the adult population in Oviedo (Spain) was obtained through randomized sampling (n = 753); a total of 308 (41%) subjects were finally included in the study. The observed oral pathology was classified according to the WHO criteria and earlier epidemiological studies.

RESULTS

A little over half of all patients (51.1%) had oral lesions. The most frequent lesions were frictional lesion (7.5%), traumatic ulcer (7.1%), denture stomatitis and pseudomembranous candidosis (6.5%), followed by melanin pigmentation (5.8%) and denture-induced hyperplasia (5.2%), plicated tongue (3.9%), lichen planus and hemangioma (3.2%), angular cheilitis and cheek biting (2.9%), fibrous hyperplasia and coated tongue (2.6%), recurrent aphthae (1.9%) and oral leukoplakia (1.6%). In relation to leukoplakia, the odds ratio (OR) of heavy drinkers was 15.98 and the OR of heavy smokers was 12.37. The OR of heavy smokers or heavy drinkers diagnosed of frictional lesion was four times greater than that of nonsmokers or nondrinkers. The OR of heavy smokers with melanic pigmentations was 4.08. The OR of complete denture wearers with candidosis was 11.38. The OR of partial removable denture wearers with hemangioma was 5.01.

CONCLUSIONS

This study shows the relation of heavy tobacco and heavy alcohol to traumatic keratosis and leukoplakia, and of complete dentures to pseudomembranous candidosis, fibrous hyperplasia and stomatitis. Programs designed to eradicate toxic factors (alcohol and tobacco) should, therefore, be implemented with adequate maintenance of dentures.

Urinary cotinine levels of smokeless tobacco (Maraş powder) users

Smokeless tobacco is used in various forms in some countries of the world. "Maraş otu" is a kind of smokeless tobacco usage in the Southeastern region of Turkey. The use of smokeless tobacco causes nicotine addiction and dependence. Moreover this type of smokeless tobacco usage is one of the risk factors for oral cancers and genotoxic damages for users. Cotinine is widely used as a biomarker of tobacco consumption and intake of nicotine. Therefore, urine samples were collected from people who are using Maraş powder and smoking cigarettes, and passive smokers, and the levels of cotinine investigated. The purpose of this study is to determine the cotinine levels of Maraş powder users and to compare the results with cigarette smokers and passive smokers. Urinary cotinine levels of subjects were determined by using capillary gas chromatography with FID detection. The mean (+/- SD) urinary cotinines have been determined as 6467.35+/-3198 microg/g creatinine for 26 Maraş powder users, 1943.92+/-1443 microg/g creatinine for 26 cigarette smokers and 198.62+/-420.82 microg/g creatinine for 26 passive smokers. A significant difference has been found between cotinine levels of Maraş powder users and cigarette smokers, which is three times higher in Maraş powder users (p<0.001). The present study suggests that smokeless tobacco poses a threat to public health and it should not be viewed as a safe alternative to cigarettes.

Oral leukoplakia

Leukoplakia has evolved as a clinico-pathologic concept over many years, with the current clinical designation being accepted worldwide. Reflective of the biology of leukoplakia is the concept of cellular atypia and epithelial dysplasia. Adding to a better understanding of leukoplakia in general has been the definition of relevant clinical subsets which, in some cases, includes etiology (snuff), while in other cases a verrucous clinical appearance will suggest a more aggressive anticipated behavior pattern. Tobacco usage, in many of its forms, remains the prime etiologic factor; however, other considerations also apply. More recently, the potential etiologic role of Candida albicans has been stressed, as well as its possible role in carcinogenesis. So-called oral hairy leukoplakia has been defined in relation to a possible Epstein-Barr viral infection, usually in the immunosuppressed patient. Other viruses, human papilloma virus in particular, have been implicated in leukoplakia, while genetic alterations involving tumor suppressor elements (p53) have also been investigated. Finally, the management of this common condition remains a variable and includes local, topical, and systemic therapies such as anti-oxidants, carotenoids, and retinoids.

Oral precancer: preventive and medical approaches to management

Leukoplakias are among the most common potentially malignant oral lesions. Some are idiopathic, others are related to habits such as tobacco and/or alcohol use. Medical management includes reducing or abandoning these habits, increasing the intake of fruit and vegetables in the diet, and possibly the use of active agents. Retinoids, carotenoids and topical cytotoxic agents show promise, and newer therapies are on the horizon.

Beta-carotene and vitamin E in oral cancer prevention

The ultimate proof that a putative chemopreventive agent does prevent cancer is a demonstration of reduced cancer incidence in a targeted population. However, because of practical and logistical considerations, such trials are virtually impossible to conduct for the majority of cancers. Therefore, a conclusion regarding the efficacy of chemopreventive activity is based on consideration of a variety of indirect lines of evidence, including laboratory studies, animal model systems, epidemiologic surveys, intervention trials involving reversal of premalignant changes, and the prevention of malignancies in particularly high risk subjects. Furthermore, the only agents worth testing are those with limited, or preferably, no toxicity, since the final use will be prevention in a generally healthy population. Beta-carotene and vitamin E both fulfill all the criteria for suitable chemopreventive agents; several lines of evidence point toward preventive roles for them in oral cancer. In numerous epidemiologic studies, low intake of beta-carotene has been associated with higher cancer risk. Both intake and supplemental use of vitamin E have been associated with a lowered risk of cancer. Smokers, whose habit is a major risk factor, have lower beta-carotene levels in oral mucosal cells when compared with non-smokers. In several laboratory and animal model systems, including the very relevant hamster cheek pouch model, these agents strongly inhibit oral cavity carcinogenesis. Beta-carotene and vitamin E produce regression of oral leukoplakia, a premalignant lesion for oral cancer. This has now been shown in seven clinical trials: five with beta-carotene alone, one with vitamin E, and one with a combination of both.(ABSTRACT TRUNCATED AT 250 WORDS)

The prevalence of oral lesions in smokeless tobacco users and an evaluation of risk factors

BACKGROUND

The widespread use of smokeless tobacco (ST) has prompted concern in regard to the development of oral lesions in long-term users.

METHODS

For inclusion in the current study, a subject must have used an ST product, either snuff or chewing tobacco, for at least 6 months. The subjects were recruited by advertising, and none was referred for the evaluation of an oral lesion. The following were performed on all subjects: assessment of exposure to ST, cigarettes, and alcohol; examination of the oral cavity; a biopsy, if an oral lesion was found; and analysis of a blood sample for beta-carotene. The dietary intake of most of the subjects was analyzed.

RESULTS

Of the 347 ST users, all of whom were white male subjects, 45 (13.0%) had an oral lesion. Thirty-five of the lesions were hyperkeratosis and 10 were epithelial dysplasia.

CONCLUSIONS

Snuff exposure was associated significantly with the presence of an oral lesion (P < 0.0001). A decreased vitamin C intake also was found among the ST users with oral lesions (P < 0.01). The ST users with epithelial dysplasia, as compared with those with hyperkeratotic lesions, were slightly older, had a lower intake of vitamin C (P < 0.05), and were more likely to have used chewing tobacco than snuff.