Javier Pintos

Relationship between dental factors and risk of upper aerodigestive tract cancer

We examined the relationship between dental health variables and risk of upper aerodigestive tract (UADT) cancers in a case-control study in Southern Brazil. The study population included 717 cases of cancers of the mouth, pharynx, and larynx and 1434 controls matched on age, gender, period of admission and study site. The association with dental factors was investigated by conditional logistic regression using extensive adjustment for a priori and empirical confounders, including tobacco and alcohol consumption, diet and sociodemographic variables. Lifetime use of dentures was not associated with risk of any UADT cancer, but history of oral sores secondary to ill-fitting dentures was associated with cancers of the mouth (odds ratio [OR] = 2.3, 95% confidence interval [CI] 1.2-4.6) and of the pharynx (OR = 2.7, 95% CI 1.1-6.2) among those using dentures. The association for mouth cancers was restricted primarily to an increased risk of tongue neoplasms (OR = 9.1, 95% CI 1.9-43.4). Less than daily tooth brushing frequency was also associated with risk of cancer of the tongue (OR = 2.1, 95% CI 1.0-4.3) and of other parts of the mouth (OR = 2.4, 95% CI 1.0-5.4). Having broken teeth was not significantly associated with risk of UADT cancer of any site. We conclude that poor oral hygiene due to infrequent tooth brushing and sores caused by dentures are risk factors for cancer of the mouth and that these associations are unlikely to be due to insufficient control of confounding.

Night Work and the Risk of Cancer Among Men

Night work might influence cancer risk, possibly via suppression of melatonin release. In a population-based case-control study conducted in Montreal, Quebec, Canada, between 1979 and 1985, job histories, including work hours, were elicited from 3,137 males with incident cancer at one of 11 anatomic sites and from 512 controls. Compared with men who never worked at night, the adjusted odds ratios among men who ever worked at night were 1.76 (95% confidence interval (CI): 1.25, 2.47) for lung cancer, 2.03 (95% CI: 1.43, 2.89) for colon cancer, 1.74 (95% CI: 1.22, 2.49) for bladder cancer, 2.77 (95% CI: 1.96, 3.92) for prostate cancer, 2.09 (95% CI: 1.40, 3.14) for rectal cancer, 2.27 (95% CI: 1.24, 4.15) for pancreatic cancer, and 2.31 (95% CI: 1.48, 3.61) for non-Hodgkins lymphoma. Equivocal evidence or no evidence was observed for cancers of the stomach (odds ratio (OR) = 1.34, 95% CI: 0.85, 2.10), kidney (OR = 1.42, 95% CI: 0.86, 2.35), and esophagus (OR = 1.51, 95% CI: 0.80, 2.84) and for melanoma (OR = 1.04, 95% CI: 0.49, 2.22). There was no evidence of increasing risk with increasing duration of night work, with risks generally being increased across all duration categories. Results suggest that night work may increase cancer risk at several sites among men.

Exposure to Diesel Motor Exhaust and Lung Cancer Risk in a Pooled Analysis from Case-Control Studies in Europe and Canada

RATIONALE Diesel motor exhaust is classified by the International Agency for Research on Cancer as probably carcinogenic to humans. The epidemiologic evidence is evaluated as limited because most studies lack adequate control for potential confounders and only a few studies have reported on exposure-response relationships. OBJECTIVES Investigate lung cancer risk associated with occupational exposure to diesel motor exhaust, while controlling for potential confounders. METHODS The SYNERGY project pooled information on lifetime work histories and tobacco smoking from 13,304 cases and 16,282 controls from 11 case-control studies conducted in Europe and Canada. A general population job exposure matrix based on ISCO-68 occupational codes, assigning no, low, or high exposure to diesel motor exhaust, was applied to determine level of exposure. MEASUREMENTS AND MAIN RESULTS Odds ratios of lung cancer and 95% confidence intervals were estimated by unconditional logistic regression, adjusted for age, sex, study, ever-employment in an occupation with established lung cancer risk, cigarette pack-years, and time-since-quitting smoking. Cumulative diesel exposure was associated with an increased lung cancer risk highest quartile versus unexposed (odds ratio 1.31; 95% confidence interval, 1.19-1.43), and a significant exposure-response relationship (P value < 0.01). Corresponding effect estimates were similar in workers never employed in occupations with established lung cancer risk, and in women and never-smokers, although not statistically significant. CONCLUSIONS Our results show a consistent association between occupational exposure to diesel motor exhaust and increased risk of lung cancer. This association is unlikely explained by bias or confounding, which we addressed by adjusted models and subgroup analyses.

Maté, coffee, and tea consumption and risk of cancers of the upper aerodigestive tract in southern brazil

Consumption of maté, a tea-like infusion of the herb Ilex paraguariensis, is common in South America. Drinkers have high risks of upper aerodigestive tract cancers, but it is conceivable that this high risk may be attributable to confounding by smoking, alcohol other exposures. To test this hypothesis, we analyzed the data from a case-control study of upper aerodigestive tract cancers conducted in Southern Brazil. We matched noncancer controls (N = 756) to cases (N = 378) on the basis of age, sex period of admission. We estimated the effect of maté consumption by conditional logistic regression with adjustment for smoking, alcohol, sociodemographics several dietary items, considered as confounders. The unadjusted relative risk (RR) for all upper aerodigestive tract cancers was 2.1 [95% confidence interval (CI) = 1.6–2.7]. Some excess risk persisted after adjustment for potential confounders (RR = 1.6; 95% CI = 1.2–2.2). Most of the excess risk for maté drinkers was for oral (RR = 1.9; 95% CI = 1.1–3.3) and laryngeal (RR = 2.2; 95% CI = 1.1–4.5) cancers. There was no evidence of associations with coffee and tea drinking. We conclude that the association of maté consumption with upper aerodigestive tract cancer risk is unlikely to result from insufficient control of confounding by critical exposures. Owing to its high prevalence in Southern South America, maté drinking may be linked to as many as 20% of all cases occurring in this region.

Occupational exposure to wood dust and risk of lung cancer in two population-based case–control studies in Montreal, Canada

BackgroundWood dust is one of the oldest and one of the most common occupational exposures in the world. The present analyses examine the effect of lifetime exposure to wood dust in diverse occupational settings on lung cancer risk.MethodsWe conducted two population-based case–control studies in Montreal: Study I (1979–1986) included 857 cases and two sets of controls (533 population and 1349 cancer controls), and Study II (1996–2001) comprised 736 cases and 894 population controls. Detailed job histories were obtained by interview and each job was evaluated by expert chemist–hygienists to estimate the likelihood and level of exposure to many substances, one of which was wood dust. Odds ratios (ORs) were computed in relation to different indices of exposure to wood dust, adjusting for several covariates including smoking. Three datasets were analysed: Study I with population controls, Study I with cancer controls, and Study II.ResultsThe most frequently exposed occupations in our study population were in construction, timber and furniture making industries. We found increased risks of lung cancer for substantial cumulative exposure to wood dust in Study I with cancer controls, (OR = 1.4: 95% confidence interval 1.0;-2.0) and in Study II (OR = 1.7: 95% confidence interval 1.1-2.7). There were no excess risks of lung cancer in any of the three datasets among workers whose cumulative exposure was not substantial. These tendencies held equally within strata of low smokers and heavy smokers.ConclusionThere was evidence of increased risk of lung cancer among workers with substantial cumulative exposure to wood dust.

Lung cancer risk associated with occupational exposure to nickel, chromium VI, and cadmium in two population‐based case–control studies in Montreal

BACKGROUND Nickel, chromium VI, and cadmium have been identified as lung carcinogens in highly exposed cohorts. The purpose of this study was to examine the etiological link between lung cancer and these metals in occupations, that usually entail lower levels of exposure than those seen in historical cohorts. METHODS Two population-based case-control studies were conducted in Montreal, from 1979 to 1986 and from 1996 to 2001, comprising 1,598 cases and 1,965 controls. A detailed job history was obtained to evaluate lifetime occupational exposure to many agents, including nickel, chromium VI, and cadmium compounds. RESULTS Lung cancer odds ratios were increased only among former or non-smokers: 2.5 (95% CI: 1.3-4.7) for nickel exposure, 2.4 (95% CI: 1.2-4.8) for chromium VI, and 4.7 (95% CI: 1.5-14.3) for cadmium. The metals did not increase risk among smokers. CONCLUSIONS While excess risks due to these metal compounds were barely discernable among smokers, carcinogenic effects were seen among non-smokers.

Human papillomavirus and prognoses of patients with cancers of the upper aerodigestive tract

Some studies have shown that human papillomavirus (HPV) infection may play not only an etiologic role in anogenital cancers but also a role in the clinical outcome. The objective of the current study was to determine whether detection of HPV DNA in primary squamous cell carcinomas of the upper aerodigestive tract (UADT) is a prognostic factor in patients with the disease.

Determinants of low-risk and high-risk cervical human papillomavirus infections in Montreal University students.

Background: Previous studies have been inconsistent about the degree of sexual transmissibility of cervical human papillomavirus (HPV) infection. The authors hypothesize that risk factors for HPV infection vary according to HPV type. Goal: To estimate the prevalence of HPV infection in asymptomatic women and to identify risk factors for overall HPV infection and HPV infection by oncogenic and nononcogenic type. Study Design: A cross‐sectional survey was conducted at the McGill University clinic in Montreal. Cervical specimens were collected from 489 female students presenting at the clinic for a routine Papanicolaou test. Data on potential risk factors was obtained by questionnaire. Human papillomavirus DNA was detected by the polymerase chain reaction using consensus primers (MY09/11) followed by hybridization with generic and type‐specific probes using Southern blot and dot blot techniques. Results: The overall HPV prevalence was 21.8%. A low‐risk HPV infection was found in 6.2% of the women, 11.8% had a high‐risk HPV infection (types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58), 7.1% had an unknown HPV type, and 2.7% had a multiple type infection. Two profiles emerged for sexual activity and risk of HPV infection according to oncogenic risk after multivariate analysis. Lifetime frequency of sexual intercourse and lifetime number of oral sex partners was associated with high‐oncogenic‐risk HPV infections; however, HPV infection with low‐oncogenic‐risk types was invariant with respect to markers of sexual activity. Conclusion: These results suggest that there are differences in epidemiologic correlates of transmission between low‐risk and high‐oncogenic‐risk HPV types based on oncogenicity. This finding has important implications for primary prevention of HPV infection and cervical cancer precursors.

Effect of type of alcoholic beverage on the risks of upper aerodigestive tract cancers in Brazil

AbstractObjectives: We investigated the effects of alcohol consumption on the risk of cancers of the upper aerodigestive tract (UADT) in a hospital-based case–control study in Brazil. Methods: A total of 784 cases of cancers of the mouth, pharynx, and larynx and 1578 non-cancer controls matched on age, gender, hospital area, and admission period provided information on alcohol drinking, smoking, and other characteristics via interview. Using logistic regression, we evaluated the relative risks (RR) of UADT cancer for different beverage types based on cumulative ethanol content exposure and frequency of consumption. Results: Relative to nondrinkers of any alcohol, risks of UADT cancers varied across sites both with increased exposure to ethanol and by alcohol type. RRs at equivalent levels of ethanol consumption were highest for cancers of the mouth for hard liquor (6.9 for > 100 kg lifetime consumption, 95% confidence interval (CI) = 2.8–17.1) and cachaça (4.5 for 101–500 kg, 95% CI = 2.2–9.0). Although RRs increased with frequency of drinks per week, when evaluated against higher proportional alcohol intake, reductions in risk were observed for beer and wine. Conclusion: Although methods of measurement can influence the interpretation of the carcinogenic nature of alcohols, increased RRs persisted with continued exposure for all types.

Effect of smoking cessation and tobacco type on the risk of cancers of the upper aero-digestive tract in Brazil.

Tobacco smoking has long been identified as the most important risk factor for upper aero-digestive tract cancers. To investigate the effect of different tobacco types and the benefit of smoking cessation, we analyzed data from a case-control study of 784 cases of mouth, pharynx, and larynx cancers and 1,578 non-cancer controls in three metropolitan hospital areas in Brazil. Subjects were interviewed as to their smoking and drinking habits, demographics, environmental exposures, occupational history, health characteristics, and diet. Controlling for total tobacco and alcohol consumption, risks for ex-smokers compared with current smokers decreased substantially with time since cessation of the habit. Compared with never smokers, ex-smokers of >20 years had a relative risk (RR) of 1.98 [95% confidence interval (CI) = 1.0-3.8] for all upper aerodigestive tract cancers. RRs for long-term (>20 years) ex-smokers tended to be lower for mouth (RR = 1.61) and pharynx (RR = 1.52) than for larynx (RR = 3.63) cancers. The benefit of quitting was strongest for commercial cigarettes (RR = 1.45, 95% CI = 0.7-3.0) for ex-smokers of >10 years, as compared with smoking of black tobacco (RR = 2.57, 95% CI = 1.4-4.6), cigars (RR = 2.59, 95% CI = 0.6-11.6), and pipe tobacco (RR = 3.40, 95% CI = 1.3-8.8).