Dose-response relationships of oral habits associated with the risk of oral pre-malignant lesions among men who chew betel quid

Betel quid, cigarettes and alcohol are well-recognized risk factors for oral cancer. However, the combined effect of the frequency and duration of these oral habits on the risk for developing oral pre-malignancies among betel quid users has not been fully addressed. In this study, an oral screening programme for men chewing betel quid was carried out by well-trained dentists for early detection of oral pre-malignancy lesions. Using generalized logit model and proportional odds model, we found that, compared with the occasional user, the adjusted odds ratios of developing leukoplakia for men chewing one to 10 pieces of betel quid, 11-20 pieces, and more than 20 pieces per day were estimated as 2.14 (95% confidence interval [CI] 1.62-2.81), 2.99 (95% CI 2.06-4.27), and 5.37 (95% CI 3.76-7.47), respectively. The corresponding figures for erythroleukoplakia were 3.69 (95% CI 1.55-8.79), 13.78 (95% CI 5.76-32.98), and 36.64 (95% CI 15.94-84.16), respectively. Similar results were found while the duration was considered. The dose-response relationships were not as noteworthy for cigarette and alcohol drinking.     

Characteristics of mutations in the p53 gene in oral squamous cell carcinoma associated with betel quid chewing and cigarette smoking in Taiwanese

p53 mutations are etiologically associated with the development of oral squamous cell carcinomas (OSCCs) or are associated with exposure to specific carcinogens. In this study, we used PCR-single strand conformation polymorphism and DNA sequencing to analyze the conserved regions of the p53 gene (exons 5-9) in OSCC tumor specimens from 187 patients with varied histories of betel quid, tobacco and alcohol use. Ninety-one of the 187 OSCCs (48.66%) showed p53 gene mutations at exons 5-9. The incidence of p53 mutations was not associated with age, sex, TNM stage, status of cigarette smoking or betel quid chewing. However, alcohol drinkers exhibited a significantly higher incidence (57/101, 56.44%) of p53 mutations than non-users (39.53%, 34/86) (P = 0.02). The effect of alcohol on the incidence of p53 mutations was still statistically significant (RR = 2.24; 95% CI, 1.21-4.15) after adjustment for cigarette smoking and betel quid (BQ) chewing. G:C to A:T transitions were the predominant mutations observed and associated with BQ and tobacco use. Alcohol drinking could enhance these transitions. After adjustment for cigarette smoking and BQ chewing, alcohol drinking still showed an independent effect on G:C to A:T transitions (RR = 2.41; 95% CI, 1.01-5.74). These findings strongly suggest an important contributive role of tobacco carcinogens to p53 mutation in this series of Taiwanese OSCCs and alcohol might enhance these mutagenic effects. As safrole-DNA adducts have been detected in 77% (23/30) of the OSCC tissues from Taiwanese oral cancer patients with a BQ chewing history, we cannot rule out the possibility that safrole or other carcinogens present in the BQ may cause a similar pattern of mutagenesis. Determination of the role of safrole and other carcinogens present in BQ on the pattern of p53 gene mutation in OSCC will require further study.     

Betel quid not containing tobacco and oral cancer: a report on a case-control study in Papua New Guinea and a meta-analysis of current evidence

Smoking and betel quid chewing are associated with increased risk of oral cancer but few studies have reported on associations in populations where betel quid does not contain tobacco. We conducted a case-control study in Papua New Guinea and a systematic review. Our case-control study recruited 143 cases with oral cancer and 477 controls. We collected information on smoking and betel quid chewing. Current smoking was associated with an increased risk of oral cancer with an adjusted odds ratio (OR) for daily smokers of 2.63 (95% confidence intervals (95% CI) 1.32, 5.22) and amongst heaviest smokers of 4.63 (95% CI 2.07, 10.36) compared to never-smokers. Betel chewing was associated with increased risk of oral cancer with an adjusted OR for current chewers of 2.03 (95% CI 1.01, 4.09) and in the heaviest chewers of 2.47 (95% CI 1.13, 5.40) compared to nonchewers. The OR in those who both smoked tobacco and chewed betel quid was 4.85 (95% 1.10, 22.25), relative to those who neither smoked nor chewed. The systematic review identified 10 previous studies that examined risk of oral cancer associated with betel quid chewing that controlled for smoking in populations where betel quid did not contain tobacco. In studies that reported results for non-smokers the combined OR was 2.14 (95% CI 1.06, 4.32) in betel quid chewers and in studies that adjusted for smoking the combined OR was 3.50 (95% CI 2.16, 5.65) in betel quid chewers. Preventive efforts should discourage betel quid chewing as well as smoking.     

Alcohol drinking outside meals and cancers of the upper aero-digestive tract

In our integrated series of case-control studies conducted in Italy and Switzerland (324 oral, 397 pharyngeal, 271 oesophageal, 506 laryngeal cancers and 3,263 controls), individuals who also drank alcoholic beverages outside meals showed an increased risk compared to those who drank at meals only. At any alcohol intake level, subjects also drinking between meals showed a more elevated risk of developing an upper aero-digestive tract cancer than subjects drinking only at meals. After adjustment for potential covariates, and, after allowance for the number of daily drinks to adjust for different alcohol-intake levels, the odds ratios for subjects reporting drinking outside meals were 1.5 (95% confidence interval [CI]: 1.0-2.2) for oral, 1.8 (95% CI: 1.3-2.5) for pharyngeal, 1.7 (95% CI: 1.2-2.5) for oesophageal and 1.2 (95% CI: 0.9-1.7) for laryngeal cancers. Our findings show that drinking pattern with respect to food consumption may influence alcohol carcinogenesis in the upper digestive and respiratory tract. An "alcohol washing effect" by chewing and swallowing is suggested.     

Expression of p53 in oral squamous cell carcinoma and its association with risk habits in southern Thailand

Tobacco smoking and alcohol drinking are the principal factors associated with p53 expression in oral squamous cell carcinomas (OSCC) in the west, whereas betel quid chewing and smokeless tobacco are important factors in the east. Variable results of p53 expression have been reported and it has been proposed that ethnic difference and a variation in the indigenous oral habit may be responsible for the finding. This study, therefore, investigated p53 expression among 106 OSCC patients from a southern Thailand population in which all four risk behaviours, tobacco smoking, alcohol drinking, betel quid chewing and use of smokeless tobacco, are practised. The associations of p53 expression with lifetime exposure to each risk behaviour were explored. Multivariate modelling showed that lifetime exposure to alcohol drinking was significantly positively associated with p53 expression (likelihood ratio P value 0.01). Betel quid chewing and tobacco smoking habit showed a trend of decreasing risk of p53 expression with increased lifetime exposure (OR 0.62, 95% CI 0.39-1.00 and OR 0.50, 95% CI 0.26-0.98, respectively). No significant association was found between p53 expression and clinico-pathological parameters. Further investigations are needed to study (1) the molecular alteration of p53 in each risk habit and (2) other possible pathways of oral carcinogenesis in betel quid- and tobacco smoking-associated OSCC in these group of patients.     

Risk of hepatocellular carcinoma and habits of alcohol drinking,betel quid chewing and cigarette smoking: a cohort of 2416 HBsAg-seropositive and 9421 HBsAg-seronegative male residents in Taiwan

Objectives: Hepatitis B virus (HBV) is a major cause of hepatocellular carcinoma (HCC) in the world. The specific aim of this study is to assess the associations between the risk of HCC and habits of alcohol drinking, betel quid chewing and cigarette smoking among subjects with and without chronic HBV infection. Methods: A total of 11,837 male residents in Taiwan were recruited in this community-based cohort study. Hepatitis B surface antigen (HBsAg) and antibody against hepatitis C virus (anti-HCV) in serum were determined by enzyme immunoassay, and the habits of alcohol drinking, betel quid chewing and cigarette smoking were collected through standardized personal interview according to a structured questionnaire. During the follow-up period of 91,885 person-years, 115 incident HCC cases were identified through data linkage with national cancer registry profile. The relative risk (RR) of developing HCC for habits of various substance use and chronic HBV infection were estimated by Cox's proportional hazards regression analyses. Results: Significantly increased HCC risk was observed for seropositives of HBsAg or anti-HCV, alcohol drinkers, betel quid chewers and cigarette smokers. There was a significant dose–response relationship between the risk of HCC and the number of habits of substance use. The highest multivariate-adjusted HCC risk was observed among HBsAg-seropositive substance users (RRs: 17.9–26.9), followed by HBsAg-seropositive non-users (RRs: 13.1–19.2), HBsAg-seronegative substance users (RRs: 1.6–2.7) and HBsAg-seronegative non-users (referent with RR = 1). The multivariate-adjusted relative HCC risks for habits of use of various substances were more profound among HBsAg-seronegatives than HBsAg-seropositive ones. Conclusion: Habitual alcohol drinking, betel quid chewing and cigarette smoking are associated with an increased risk of HCC. Abstinence from substance use is important for the prevention of HCC in areas where chronic HBV infection is endemic.     

The neoplastic impact of tobacco-free betel-quid on the histological type and the anatomical site of aerodigestive tract cancers

Little is known about any consequences of swallowing tobacco-free betel-quid (TF-BQ) juice/remnants following chewing and its carcinogenic impact on the upper aerodigestive tract (UADT) to gastrointestinal tract (GIT). We investigated the neoplastic impact of TF-BQ on different anatomical locations along UADT and GIT, and differences according to their histological categories. We conducted a multicenter case-control study examining patients with 2,163 pathology-proven UADT and GIT cancers, comparing them with 2,250 control subjects. Generalized additive models, piecewise regression and polytomous logistic models were applied to identify possible dose-dependent structures and cancer risks. Contrary to nonsignificant GIT-adenocarcinoma risk (aOR=0.9), TF-BQ users experienced a 1.7- to 16.2-fold higher risk of UADT-squamous cell carcinomas than nonusers, with the peak risk discovered in oral neoplasms. We separately observed a curvilinear and linear TF-BQ dose-risk relationship in oral/pharyngeal/esophageal and laryngeal cancers. Chewers of betel inflorescence were generally at a greater UADT cancer risk. A higher first-piecewise increased risk of esophageal cancer was recognized among areca-fluid swallowers than among nonswallowers (continuous aOR=1.12 vs. 1.03). TF-BQ use accounted for 66.1-78.7% and 17.8-33.2% of the cases of oral/pharyngeal and esophageal/laryngeal cancers, respectively. However, a reduction from heavy TF-BQ consumption to low-to-moderate consumption only reduced 11.3-34.6% of etiologic fraction of oral/pharyngeal cancers. Alcohol supra-additively modified the risk of TF-BQ in determining the development of oral, pharyngeal and esophageal cancers. In conclusion, the interplay of TF-BQ and alcohol/tobacco use, combined with how chewing habit is practiced, influences carcinogenic consequences on anatomically diverse sites of UADT and GIT cancers, and histologically different types.     

Family history and the risk of oral and pharyngeal cancer

Scanty data are available on familial risk in oral and pharyngeal cancer. The relationship between oral and pharyngeal cancer and family history of cancer in first-degree relatives was investigated using data from a multicentric case-control study conducted in Italy and Switzerland between 1992 and 2005 on 956 cases aged less than 79 years, with histologically confirmed incident oral and pharyngeal cancer, and 2362 controls admitted to hospital for acute, nonneoplastic conditions. Logistic regression models conditioned on sex, age, study centre, and including terms for education, tobacco smoking, alcohol drinking, and number of siblings were used to estimate the odds ratios (OR) of oral and pharyngeal cancer. The multivariate ORs were similar for a family history of oral and pharyngeal cancer (2.6, 95% confidence interval, CI, 1.5-4.5) and laryngeal cancer (3.8, 95% CI, 2.0-7.2). The OR was 3.1 (95% CI, 2.0-4.8) for oral and pharyngeal cancer and laryngeal cancer combined. The OR was 7.1 (95% CI, 1.3-37.2) for subjects with 2 or more first-degree relatives with oral and pharyngeal/laryngeal cancers. Significant increases in risk were also observed for a family history of melanoma (OR = 5.8; 95% CI, 1.3-26.4) and lung cancer (OR = 1.4; 95% CI, 1.0-2.0). Compared to subjects without family history, nonsmokers, and non or moderate drinkers, the OR was 42.6 for current smokers, heavy drinkers with family history. History of oral and pharyngeal cancer and laryngeal cancer is a strong determinant of oral and pharyngeal cancer risk, independent from tobacco and alcohol.     

Does pizza protect against cancer?

We analyzed the potential role of pizza on cancer risk, using data from an integrated network of case-control studies conducted in Italy between 1991 and 2000. Cancer sites were: oral cavity and pharynx (598 cases), esophagus (304 cases), larynx (460 cases), colon (1,225 cases) and rectum (728 cases). Controls were 4,999 patients admitted for acute, non-neoplastic conditions to the same hospital network as cases. Odds ratios for regular pizza consumers were 0.66 (95% confidence interval, CI = 0.47-0.93) for oral and pharyngeal cancer, 0.41 (95% CI = 0.25-0.69) for oesophageal, 0.82 (95% CI = 0.56-1.19) for laryngeal, 0.74 (95% CI = 0.61-0.89) for colon and 0.93 (95% CI = 0.75-1.17) for rectal cancer. Pizza appears therefore to be a favorable indicator of risk for digestive tract neoplasms in this population.     

Betel quid not containing tobacco and oral leukoplakia: a report on a cross-sectional study in Papua New Guinea and a meta-analysis of current evidence

Leukoplakia is an asymptomatic, potentially malignant change in the oral mucosa. Previous studies have reported that smoking and betel quid chewing are associated with increased risk of leukoplakia; few studies have reported on these associations in populations where betel quid does not contain tobacco. We conducted a case-control study nested in a cross-sectional study in Papua New Guinea and a systematic review of studies that included chewers of betel quid without tobacco. Our study recruited 1,670 adults. We recorded betel quid chewing and smoking. The prevalence of leukoplakia was 11.7%. In the nested case-control study of 197 cases and 1,282 controls, current betel chewing was associated with increased risk of leukoplakia with an adjusted odds ratio for current chewers of 3.8 (95% CI 1.7, 8.4) and in the heaviest chewers of 4.1 (95% CI 1.8, 9.1) compared to non-chewers. Current smoking was associated with an increased risk of leukoplakia with an adjusted odds ratio for current smokers of 6.4 (95% CI 4.1, 9.9) and amongst heaviest smokers of 9.8 (95% CI 5.9, 16.4) compared to non-smokers. The systematic review identified 5 studies examining risk of leukoplakia associated with betel quid chewing in populations where betel quid did not contain tobacco and that controlled for smoking. In studies that adjusted for smoking, the combined random effect odds ratio was 7.9 (95% CI 4.3, 14.6) in betel quid chewers. The results of this study and systematic review of similar studies provide evidence of the role of betel quid not containing tobacco and leukoplakia.     

Impact of RECK gene polymorphisms and environmental factors on oral cancer susceptibility and clinicopathologic characteristics in Taiwan

Oral cancer is the fourth common male cancer and causally associated with environmental carcinogens in Taiwan. The reversion-inducing-cysteine-rich protein with Kazal motifs (RECK) has a significant effect on tumorigenesis by limiting angiogenesis and invasion of tumors through the extracellular matrix. RECK downregulation has been confirmed in many human cancers and associated with lymph node metastasis clinically. In the present hospital-based case-controlled study, the demographic, RECK genotype and clinicopathologic data from 341 male oral cancer patients and 415 cancer-free controls were investigated. We found that RECK rs10814325, rs16932912, rs11788747 or rs10972727 polymorphisms were not associated with oral cancer susceptibility. Among 488 smokers, RECK polymorphisms carriers with betel quid chewing have a 7.62-fold [95% confidence interval (CI), 2.96-19.64] to 25.33-fold (95% CI, 9.57-67.02) risk to have oral cancer compared with RECK wild-type carrier without betel quid chewing. Among 352 betel quid chewers, RECK polymorphisms carriers with smoking have a 6.68-fold (95% CI, 1.21-36.93) to 18.57-fold (95% CI, 3.80-90.80) risk to have oral cancer compared with those who carried wild-type without smoking. In 263 betel quid chewing oral cancer patients, RECK rs10814325 polymorphism have a 2.26-fold (95% CI, 1.19-4.29) risk to have neck lymph node metastasis compared with RECK wild-type carrier. These results support that gene-environment interactions between the RECK polymorphisms, smoking and betel quid may alter oral cancer susceptibility and metastasis.     

Family History of Cancer and Head and Neck Cancer Risk in a Chinese Population

Background: The aim of this study was to investigate whether family history of cancer is associated with head and neck cancer risk in a Chinese population. Materials and Methods: This case-control study included 921 cases and 806 controls. Recruitment was from December 2010 to January 2015 in eight centers in East Asia. Controls were matched to cases with reference to sex, 5-year age group, ethnicity, and residence area at each of the centers. Results: We observed an increased risk of head and neck cancer due to first degree family history of head and neck cancer, but after adjustment for tobacco smoking, alcohol drinking and betel quid chewing the association was no longer apparent. The adjusted OR were 1.10 (95% CI=0.80-1.50) for family history of tobacco-related cancer and 0.96 (95%CI=0.75-1.24) for family history of any cancer with adjustment for tobacco, betel quid and alcohol habits. The ORs for having a first-degree relative with HNC were higher in all tobacco/ alcohol subgroups. Conclusions: We did not observe a strong association between family history of head and neck cancer and head and neck cancer risk after taking into account lifestyle factors. Our study suggests that an increased risk due to family history of head and neck cancer may be due to shared risk factors. Further studies may be needed to assess the lifestyle factors of the relatives.     

Lifetime risk of distinct upper aerodigestive tract cancers and consumption of alcohol,betel and cigarette

The cancer of upper aerodigestive tract (UADT) is a common cancers in the world. However, its lifetime risk by consumption of alcohol, betel and cigarettes remain to be elucidated. This study aimed to estimate lifetime risk of distinct UADT cancers and assess their associations with alcohol, betel and cigarette consumption. Three cohorts of 25,611 men were enrolled in 1982–1992 in Taiwan. The history of alcohol, betel and cigarette consumption was enquired through questionnaire interview. Newly developed UADT cancers were ascertained through computerized linkage with national cancer registry profile. Lifetime (30–80 years old) risk and multivariate‐adjusted hazard ratio (HR_adj) of distinct UADT cancers by alcohol, betel and cigarette consumption were estimated. A total of 269 pathologically confirmed cases of UADT cancers were newly‐diagnosed during 472,096 person‐years of follow‐up. The lifetime risk of UADT cancer was 9.42 and 1.65% for betel chewers and nonchewers, 3.22 and 1.21% for cigarette smokers and nonsmokers and 4.77 and 1.85% for alcohol drinkers and nondrinkers. The HR_adj (95% confidence interval) of developing UADT cancer was 3.36 (2.51–4.49), 2.02 (1.43–2.84), 1.90 (1.46–2.49), respectively, for the consumption of betel, cigarette and alcohol. Alcohol, betel and cigarette had different effect on cancers at various anatomical sites of UADT. The cancer risk from the mouth, pharynx, esophagus to larynx increased for alcohol and cigarette consumption, but decreased for betel consumption. Alcohol, betel and cigarette consumption are independent risk predictors for distinct UADT cancers.     

Light alcohol drinking and cancer: a meta-analysis

BackgroundThere is convincing evidence that alcohol consumption increases the risk of cancer of the colorectum, breast, larynx, liver, esophagus, oral cavity and pharynx. Most of the data derive from studies that focused on the effect of moderate/high alcohol intakes, while little is known about light alcohol drinking (up to 1 drink/day).Patients and methodsWe evaluated the association between light drinking and cancer of the colorectum, breast, larynx, liver, esophagus, oral cavity and pharynx, through a meta-analytic approach. We searched epidemiological studies using PubMed, ISI Web of Science and EMBASE, published before December 2010.ResultsWe included 222 articles comprising ∼92 000 light drinkers and 60 000 non-drinkers with cancer. Light drinking was associated with the risk of oropharyngeal cancer [relative risk, RR = 1.17; 95% confidence interval (CI) 1.06–1.29], esophageal squamous cell carcinoma (SCC) (RR = 1.30; 95% CI 1.09–1.56) and female breast cancer (RR = 1.05; 95% CI 1.02–1.08). We estimated that ∼5000 deaths from oropharyngeal cancer, 24 000 from esophageal SCC and 5000 from breast cancer were attributable to light drinking in 2004 worldwide. No association was found for colorectum, liver and larynx tumors.ConclusionsLight drinking increases the risk of cancer of oral cavity and pharynx, esophagus and female breast.     

No association between gastroesophageal reflux and cancers of the larynx and pharynx.

PURPOSE: To examine the proposed relation between gastroesophageal reflux disease and cancers of the larynx and pharynx. EXPERIMENTAL DESIGN: A cohort of 66,965 patients with discharge diagnoses of heartburn, hiatal hernia, or esophagitis was identified in the Swedish Inpatient Register. We observed a total of 376,622 person-years in the cohort. Identification of laryngeal and pharyngeal cancers was achieved through the Swedish Cancer Register. Standardized incidence ratios, the ratio of the observed to the expected number of cancers, derived from the general Swedish population and adjusted for sex, age, and calendar year, was used to estimate the relative risk. RESULTS: During follow-up, 30 cases of laryngeal and 31 cases of pharyngeal cancer were detected in the cohort. Slightly increased risks of laryngeal [relative risk, 1.6; 95% confidence interval (CI), 1.1-2.2] and pharyngeal carcinomas (relative risk, 1.9; 95% CI, 1.3-2.8) were observed in the total reflux cohort. After stratification to exclude cohort members with a diagnosis of alcoholism, no significant increase in the risk of laryngeal (relative risk, 1.3; 95% CI, 0.8-2.0) or pharyngeal carcinomas (relative risk, 1.0; 95% CI, 0.5-1.6) was found compared with the general population. Furthermore, there were no dose-response patterns of the risk for laryngeal and pharyngeal cancers with years of cohort follow-up, indicators of reflux severity, or specificity of reflux diagnosis. CONCLUSION: This study provides no evidence in support of the proposed association between gastroesophageal reflux disease and cancers of the larynx or pharynx.     

Betel quid chewing as a risk factor for hepatocellular carcinoma: a case-control study

The role of betel quid chewing in the aetiology of hepatocellular carcinoma (HCC) was evaluated in a case-control study including 263 pairs of age- and sex-matched HCC patients and healthy controls. Serum hepatitis B surface antigen (HBsAg), and antibodies to hepatitis C virus (anti-HCV) were determined, and standardized personal interview conducted using a structured questionnaire. Multivariate analysis indicated that betel quid chewing (odds ratio (OR), 3.49; 95% confidence interval (CI), 1.74-6.96), HBsAg (OR, 16.69; 95% CI, 9.92-28.07), anti-HCV (OR, 38.57; 95% CI, 18.15-81.96), and educational duration of less than 10 years (OR, 1.71; 95% CI, 1.05-2.78) are independent risk factors of HCC. In addition, there was an additive interaction between betel quid chewing and chronic infection with either hepatitis B virus (synergy index, 5.37) or hepatitis C virus (synergy index, 1.66). Moreover, risk on HCC increased as duration of betel quid chewing increased, or amount of betel quid consumed (each P for trend < 0.0001).     

Laryngeal cancer in women: tobacco, alcohol, nutritional, and hormonal factors.

Laryngeal cancer is the neoplasm with the largest male to female sex ratio in most populations. Thus, inadequate data are available on women. We analyzed several risk factors in the combined dataset from two case-control studies conducted between 1986 and 2000 in northern Italy and Switzerland. Cases were 68 women under age 79 years, with incident, histologically confirmed cancer of the larynx. Controls were 340 women, admitted to the same network of hospitals as cases, for acute, nonmalignant conditions, unrelated to tobacco and alcohol consumption. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated by logistic regression models, conditioned by age, study center and year of interview, and including terms for education, body mass index, tobacco, alcohol drinking, and nonalcohol energy intake. Laryngeal cancer was strongly associated with cigarette smoking (OR = 435.7, 95% CI: 38.2-4964.4 for smokers of >/=25 cigarettes/day) and alcohol drinking (OR = 4.3, 95% CI: 0.8-24.1 for >/=5 drinks/day). An inverse relation was found for vegetables (OR = 0.3, 95% CI: 0.1-0.9 for the highest level of consumption), fruit (OR = 0.5, 95% CI: 0.2-1.3), and olive oil (OR = 0.3, 95% CI: 0.1-0.9). Reproductive and hormonal factors were not consistently associated to laryngeal cancer risk. This investigation, based on a uniquely large number of laryngeal cancers in women, provides definite evidence that cigarette smoking is the prominent risk factor for laryngeal cancer in women, accounting for 78% of cases in this population. Alcohol and selected dietary aspects account for approximately 30% of cases, whereas menstrual and hormonal factors do not appear to have a consistent role in laryngeal carcinogenesis.     

Chewing areca nut, betel quid, oral snuff, cigarette smoking and the risk of oesophageal squamous-cell carcinoma in South Asians: a multicentre case-control study

Oesophageal cancer remains an important public health problem worldwide. This multicentre matched case-control study examined the chewing areca nut alone, betel quid with tobacco, oral snuff (snuff dipping) and cigarette smoking as the risk factors for oesophageal squamous-cell carcinoma. We enrolled 91 cases of oesophageal squamous-cell carcinoma and 364 matched controls from three tertiary-care hospitals in Karachi, Pakistan. A structured questionnaire was used to collect the data through face-to-face interview of the participants. Multivariable conditional logistic regression model showed that after adjusting for the effect of ethnicity, ever chewed areca nut alone (adjusted matched odds ratio (mOR(adj))=3.7; 95% confidence interval (CI): 1.6-8.5), ever chewed betel quid with tobacco (mOR(adj)=12.8; 95% CI: 6.3-26.2), ever practiced snuff dipping (mOR(adj)=4.3; 95% CI: 1.6-11.7) and ever smoked cigarettes (mOR(adj)=2.9; 95% CI: 1.4-5.9) were significantly and independently associated with oesophageal squamous-cell carcinoma status. The adjusted summary population attributable risk (PAR) percent for all four substances together was 67.0. Furthermore, despite incomplete synergy, there was manifold increase in the risk of oesophageal squamous-cell carcinoma, if the respondents ever smoked cigarettes and ever chewed betel quid with tobacco (mOR(adj)=21.4; 95% CI: 6.3-72.4) or if they ever smoked cigarettes and ever practiced snuff dipping (mOR(adj)=14.4; 95% CI: 2.3-91.1). The adjusted PAR (%) was higher for the dual practice of smoking cigarettes and chewing betel quid with tobacco (64.3) than the dual practice of smoking cigarettes and snuff dipping (32.2). Public awareness to curtail the addiction to these substances may result in a substantial reduction in the incidence of oesophageal squamous-cell carcinoma and related mortality in this and similar settings.     

Head and neck cancer prevention: from primary prevention to impact of clinicians on reducing burden

Survival from head and neck cancers (HNCs) of the lip, oral cavity, pharynx, and larynx has increased by 10% over the past few decades. Little over half of patients who develop HNCs will survive beyond 5 years. Survival is lower for individuals in many countries where traditional risk factors such as tobacco smoking, alcohol drinking, and betel quid chewing are highly prevalent but tertiary health care center access is limited or unavailable. Early diagnosis of HNC is the most important prognostic factor for each tumor site. Molecular-based research on HNC tumors holds promise for early stage detection, screening, vaccination, disease follow-up, and progression. Future investments for HNC control must consider both effectiveness and sustainability for both high- and low-resource countries alike, with priority toward risk factor prevention and earlier diagnosis.     

A novel single nucleotide polymorphism in ERCC6 gene is associated with oral cancer susceptibility in Taiwanese patients

The DNA repair gene ERCC6, an important caretaker of the overall genome stability, is thought to play a role in the development of human malignancy. However, the polymorphic variants of ERCC6, has never been reported about their association with oral cancer susceptibility. In this hospital-based case-control study, the association of ERCC6 codon 399, 1097 and 1413 polymorphisms with oral cancer risk in a Central Taiwanese population was first investigated. In total, 292 patients with oral cancer and 290 age- and gender-matched healthy controls recruited from the China Medical Hospital in Central Taiwan were genotyped. We found a significant different distribution in the frequency of the ERCC6 codon 399 genotypes, but not the ERCC6 codon 1097 or 1413 genotypes, between the oral cancer and control groups. Those who had homozygous A/A or heterozygous A/G at ERCC6 codon 399 showed a 1.82- and 1.22-fold (95% confidence interval=1.19-2.79 and 0.83-1.78, respectively) increased risk of oral cancer compared to those with G/G. As for ERCC6 codon 1097 or 1413, there was no difference in distribution between the oral cancer and control groups. Gene-environment interactions with smoking and betel quid chewing, but not alcohol drinking, were significant for ERCC6 polymorphisms. ERCC6 codon 399, G/A+A/A ever user groups exhibited an increased risk of 2.36 (95% CI=1.36-4.10) for smoking and 2.72 (95% CI=1.31-5.63) for betel quid chewing. Our results firstly suggest that the heterozygous and homozygous A allele of the ERCC6 codon 399 may be associated with the development of oral cancer and may be a novel useful marker for primary prevention and anticancer intervention.