Early age at smoking initiation and tobacco carcinogen DNA damage in the lung

A tale as old as time - the importance of accelerated lung aging in chronic obstructive pulmonary disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is progressive in nature and predominantly affects older individuals. Lung function decline is a typical part of the aging process, characterized by gradual loss of lung mechanics, airway remodeling, persistent low-grade inflammation of the airways, compromised epithelial barrier function, and impaired immune responses over time.

AREAS COVERED

The pathology of the senile lung is advanced in patients with COPD, whereby genomic damages contribute to structural defects and cellular dysfunction. Primary, antagonistic, and integrative hallmarks of aging are accelerated in COPD, potentiated by cumulative injury sustained from repeated environmental exposures and the interaction with comorbidities. Identification of epigenetic profiles in COPD indicates how cellular processes contribute to the advancement of biological age. Epigenetic abnormalities unique to COPD subpopulations occur in individuals who are immunodeficient, and often experience early onset and increased severity of COPD.

EXPERT OPINION

Accelerated aging processes indicated by epigenetic and other biomarkers may be a promising avenue for early detection, prevention, and subsequent management of COPD. Understanding risk factors contributing to progressive lung function decline and implementation of mitigation strategies such as cessation of smoking, repurposing existing pharmacotherapeutics and development of novel therapies may slow age-related pathologies in COPD. [Figure: see text].

Tobacco Patterns and Risk of Chronic Obstructive Pulmonary Disease: Results From a Cross-Sectional Study

INTRODUCTION

There is still uncertainty about which aspects of cigarette smoking influence the risk of Chronic Obstructive Pulmonary Disease (COPD). The aim of this study was to estimate the COPD risk as related to duration of use, intensity of use, lifetime tobacco consumption, age of smoking initiation and years of abstinence.

METHODS

We conducted an analytical cross-sectional study based on data from the EPISCAN-II study (n=9092). All participants underwent a face-to-face interview and post-bronchodilator spirometry was performed. COPD was defined as post-bronchodilator FEV1/FVC<70%. Parametric and nonparametric logistic regression models with generalized additive models were used.

RESULTS

8819 persons were included; 858 with COPD and 7961 without COPD. The COPD risk increased with smoking duration up to ≥50 years [OR 3.5 (95% CI: 2.3-5.4)], with smoking intensity up to ≥39cig/day [OR 10.1 (95% CI: 5.3-18.4)] and with lifetime tobacco consumption up to >29 pack-years [OR 3.8 (95% CI: 3.1-4.8)]. The COPD risk for those who started smoking at 22 or later was 0.9 (95% CI: 0.6-1.4). The risk of COPD decreased with increasing years of cessation. In comparison with both never smokers and current smokers, the lowest risk of COPD was found after 15-25 years of abstinence.

CONCLUSION

COPD risk increases with duration, intensity, and lifetime tobacco consumption and decreases importantly with years of abstinence. Age at smoking initiation shows no effect. After 15-25 years of cessation, COPD risk could be equal to that of a never smoker. This work suggests that the time it takes to develop COPD in a smoker is about 30 years.

Secondhand Smoke Exposure During Childhood and Cancer Mortality in Adulthood Among Never Smokers: The Japan Collaborative Cohort Study for Evaluation of Cancer Risk

We examined whether secondhand smoke exposure during childhood was associated with cancer mortality in adulthood among never smokers. In the Japan Collaborative Cohort Study for Evaluation of Cancer Risk, we analyzed data from 45,722 Japanese lifetime nonsmokers aged 40-79 years with no history of cancer at baseline (1988-1990) who had completed a lifestyle questionnaire, including information on the number of family members who had smoked at home during their childhood (0, 1, 2, or ≥3 family members). A Cox proportional hazards model and competing-risks regression were used to calculate multivariable hazard ratios and subdistribution hazard ratios with 95% confidence intervals for overall and site-specific cancer mortality according to the number of family members who smoked during the participant's childhood, after adjusting for potentially confounding factors. During a median follow-up period of 19.2 years, a total of 2,356 cancer deaths were documented. Secondhand smoke exposure was positively associated with the risk of mortality from pancreatic cancer in adulthood; the multivariable hazard ratio for having 3 or more family members who smoked (as compared with none) was 2.32 (95% confidence interval: 1.14, 4.72). Associations were not evident for total cancer risk or risk of other types of smoking-related cancer. In this study, secondhand smoke exposure during childhood was associated with an increased risk of pancreatic cancer mortality in adulthood.

Rare Occurrence of Aristolochic Acid Mutational Signatures in Oro-Gastrointestinal Tract Cancers

BACKGROUND

Aristolochic acids (AAs) are potent mutagens commonly found in herbal plant-based remedies widely used throughout Asian countries.

PATIENTS AND METHODS

To understand whether AA is involved in the tumorigenesis of the oro-gastrointestinal tract, we used whole-exome sequencing to profile 54 cases of four distinct types of oro-gastrointestinal tract cancer (OGITC) from Taiwan.

RESULTS

A diverse landscape of mutational signatures including those from DNA mismatch repair and reactive oxygen species was observed. APOBEC mutational signatures were observed in 60% of oral squamous cell carcinomas. Only one sample harbored AA mutational signatures, contradictory to prior reports of cancers from Taiwan. The metabolism of AA in the liver and urinary tract, transient exposure time, and high cell turnover rates at OGITC sites may explain our findings.

CONCLUSION

AA signatures in OGITCs are rare and unlikely to be a major contributing factor in oro-gastrointestinal tract tumorigenesis.

Cancer burden in China: trends, risk factors and prevention

As the most populous country in the world, China has made strides in health promotion in the past few decades. With the aging population, the burden of cancer in China continues to grow. Changes in risk factors for cancer, especially diet, obesity, diabetes, and air pollution, continue to fuel the shift of cancer transition in China. The burden of upper gastrointestinal cancer in China is decreasing, but still heavy. The rising burden of colorectal, prostate, and breast cancers is also significant. Lung cancer became the top cause of cancer-related deaths, together with smoking as the most important contributor to cancer deaths. The Chinese government has taken several approaches to control cancer and cancer-related risk factors. Many achievements have been made, but some challenges remain. Health China 2030 is ambitious and depicts a bright vision of the future for cancer control in China. The decrease in the cancer burden in China will require cross-sector collaboration and coordinated efforts on primary and secondary preventions by governments, public health organizations, and individuals. In this review, we describe the trends of cancer burden and discuss cancer-related risk factors in China, identifying strategies to reduce the burden of cancer in China.

Trends in E-Cigarette, Cigarette, Cigar, and Smokeless Tobacco Use Among US Adolescent Cohorts, 2014-2018

Objectives. To examine changes in age of initiation of e-cigarette, cigarette, cigar, and smokeless tobacco use among adolescents in the United States.Methods. We used data from 5 cohorts of the National Youth Tobacco Survey (2014-2018; n = 26 662).Results. In 2014, 8.8% of lifetime e-cigarette users initiated use at 14 years or younger, as compared with 28.6% of lifetime e-cigarette users in 2018. There was no such change in initiation ages for cigarettes, cigars, and smokeless tobacco among lifetime users of each of these products.Conclusions. US adolescents are initiating e-cigarette use at younger ages in recent years. This is concerning given the association of e-cigarette use with subsequent cigarette use. Continued surveillance of these trends and additional prospective research are needed. Tobacco prevention programs, policies, and regulations that make it more difficult for youths to obtain e-cigarettes are warranted.

Age at start of using tobacco on the risk of head and neck cancer: Pooled analysis in the International Head and Neck Cancer Epidemiology Consortium (INHANCE)

BACKGROUND

Tobacco use is a well-established risk factor for head and neck cancer (HNC). However, less is known about the potential impact of exposure to tobacco at an early age on HNC risk.

METHODS

We analyzed individual-level data on ever tobacco smokers from 27 case-control studies (17,146 HNC cases and 17,449 controls) in the International Head and Neck Cancer Epidemiology (INHANCE) consortium. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using random-effects logistic regression models.

RESULTS

Without adjusting for tobacco packyears, we observed that younger age at starting tobacco use was associated with an increased HNC risk for ever smokers (OR<10 years vs. ≥30 years: 1.64, 95% CI: 1.35, 1.97). However, the observed association between age at starting tobacco use and HNC risk became null after adjusting for tobacco packyears (OR<10 years vs. ≥30 years: 0.97, 95% CI: 0.80, 1.19). In the stratified analyses on HNC subsites by tobacco packyears or years since quitting, no difference in the association between age at start and HNC risk was observed.

CONCLUSIONS

Results from this pooled analysis suggest that increased HNC risks observed with earlier age at starting tobacco smoking are largely due to longer duration and higher cumulative tobacco exposures.

CHRNA5 and CHRNA3 polymorphism and lung cancer susceptibility in Palestinian population

Objective

The genetic polymorphism (rs16969968 in CHRNA5, and rs1051730 in CHRNA3 genes) were recently shown to be associated with risk of LC. The aim of this study is to elucidate whether they predispose Palestinian individuals to lung cancer, and how is this related to smoking.

Results

Frequency of the rs16969968-A allele was significantly higher in the case group (36.7%) than in normal controls (17.5%; P = 0.022; OR = 6.83 for AA and 2.81 for AG genotypes). The frequency of rs1051730-T allele was also significantly higher in the case group (46.7%) than in the control group (22.5%; P = 0.001; OR = 2.20 for TC and 13.22 for TT genotypes). Frequency of rs16969968-A allele was higher in smokers (29.1%) than nonsmokers (15.7%) regardless of lung cancer; similarly, frequency of rs1051730-T allele was also higher in smokers than in smokers (46.7% vs 22.5%, respectively). The higher the proportion of the risk allele (rs16969968-A and rs1051730-T), the higher the mean number of daily consumed cigarettes (P = 0.006). Carrying rs16969968-A and/or rs1051730-T alleles results in an increased risk to lung cancer probably by increasing the individual’s tendency for heavy smoking. The allelic frequency of the rs16969968-A and rs1051730-T alleles among normal Palestinian controls is similar to different populations worldwide.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3310-0) contains supplementary material, which is available to authorized users.

A School-Based Intervention Program to Prevent Adolescent Smoking

Research has shown that tobacco use usually begins in early adolescence, results in an increase in future health problems, and ultimately affects national health care costs. Despite the messages about the dangers of smoking, young people continue to smoke. A school-based tobacco education program designed to produce a more favorable attitude about the positive effects of not smoking and increase knowledge of the hazards of smoking was implemented for 6th graders in a parochial middle school. After the intervention, there was a significant increase in knowledge about tobacco but no change in attitudes regarding the use of tobacco. The results have implications for school nurses who design and teach programs to prevent tobacco use.

Electronic cigarettes: an aid in smoking cessation, or a new health hazard?

The issue of electronic cigarettes is one of the most controversial topics in public health. There is intense debate and dividing opinions about their use patterns, health effects and association with smoking. This is expected since they were only recently introduced to the market and they refer to a harm-reduction approach and strategy that is not universally accepted for smoking and tobacco use in the public health community. Three main factors determine the public health impact of electronic cigarettes: (1) their safety/risk profile, both relative to smoking and in absolute terms; (2) their effectiveness for smoking reduction and cessation; (3) the patterns of use by different population subgroups, especially never-smokers, and adoption of use by youth. This analysis presents a brief overview of currently available evidence and gaps in research covering these three factors.

EGFR mutation, smoking, and gender in advanced lung adenocarcinoma

Purpose

In the current targeted therapy era, information on the effect of smoking in epidermal growth factor receptor (EGFR)-mutant lung cancer patients is scarce.

Results

In total, 11,678 adenocarcinoma patients were enrolled. Of these, 33.3% and 91.8% of male and female patients were non-smokers, respectively. An increased amount of smoking (P < 0.001 for trend), fewer smoke-free years (P < 0.001 for trend), and younger age of smoking initiation (P = 0.034 for trend) were all associated with significantly lower EGFR mutation rates. Smokers had a shorter median overall survival (OS) among both EGFR-mutant and EGFR-wild type patients (17.8 vs. 21.1 months, and 7.9 vs. 11.4 months respectively; both P < 0.001). Among patients with EGFR-mutant adenocarcinoma, younger smokers were associated with shorter OS (P = 0.047). In multivariate analysis, female gender was an independent prognostic factor for OS (hazard ratio: 0.86 [95% confidence interval {CI}: 0.80-0.93]; P < 0.001 in the EGFR-mutant group and 0.88 [95% CI: 0.81-0.96]; P = 0.004 in the EGFR-wild type group).

Materials and Methods

We reviewed the National Lung Cancer database (Taiwan) to assess the impact of smoking on the EGFR mutation rate and survival in advanced lung adenocarcinoma patients during 2011 and 2014 retrospectively.

Conclusions

Smoking was associated with lower incidence of EGFR mutation rate and reduced OS of advanced lung adenocarcinoma patients in a dose-dependent manner. In addition to EGFR mutation and smoking, gender also plays an important role in survival among these patients.

Environmental tobacco smoke exposure and EGFR and ALK alterations in never smokers' lung cancer. Results from the LCRINS study

Environmental tobacco smoke (ETS) exposure is a main risk factor of lung cancer in never smokers. Epidermal Growth Factor Receptor (EGFR) mutations and ALK translocations are more frequent in never smokers' lung cancer than in ever-smokers. We performed a multicenter case-control study to assess if ETS exposure is associated with the presence of EGFR mutations and its types and if ALK translocations were related with ETS exposure. All patients were never smokers and had confirmed lung cancer diagnosis. ETS exposure during childhood showed a negative association on the probability of EGRF mutation though not significant. Exposure during adulthood, at home or at workplace, did not show any association with EGFR mutation. The mutation type L858R seemed the most associated with a lower probability of EGFR alterations for ETS exposure at home in adult life. There is no apparent association between ETS exposure and ALK translocation. These results might suggest that ETS exposure during childhood or at home in adult life could influence the EGFR mutations profile in lung cancer in never smokers, reducing the probability of presenting EFGR mutation.

Impact of Age at Smoking Initiation on Smoking-Related Morbidity and All-Cause Mortality

INTRODUCTION

Using a nationally representative sample of U.S. adults, the aims of this study were to examine the impact of early smoking initiation on the development of self-reported smoking-related morbidity and all-cause mortality.

METHODS

National Health Interview Survey data from 1997 through 2005 were linked to the National Death Index with follow-up to December 31, 2011. Two primary dependent variables were smoking-related morbidity and all-cause mortality; the primary independent variable was age of smoking initiation. The analyses included U.S. population of current and former smokers aged ≥30 years (N=90,278; population estimate, 73.4 million). The analysis relied on fitting logistic regression and Cox proportional hazards models.

RESULTS

Among the U.S. population of smokers, 7.3% started smoking before age 13 years, 11.0% at ages 13-14 years, 24.2% at ages 15-16 years, 24.5% at ages 17-18 years, 14.5% at ages 19-20 years, and 18.5% at ages ≥21 years. Early smoking initiation before age 13 years was associated with increased risks for cardiovascular/metabolic (OR=1.67) and pulmonary (OR=1.79) diseases as well as smoking-related cancers (OR=2.1) among current smokers; the risks among former smokers were cardiovascular/metabolic (OR=1.38); pulmonary (OR=1.89); and cancers (OR=1.44). Elevated mortality was also related to early smoking initiation among both current (hazard ratio, 1.18) and former smokers (hazard ratio, 1.19).

CONCLUSIONS

Early smoking initiation increases risks of experiencing smoking-related morbidities and all-cause mortality. These risks are independent of demographic characteristics, SES, health behaviors, and subsequent smoking intensity. Comprehensive tobacco control programs should be implemented to prevent smoking initiation and promote cessation among youth.

Treatment of Lung Cancer in Medically Compromised Patients

Outcomes for patients with lung cancer have been improved substantially through the integration of surgery, radiation, and systemic therapy for patients with early-stage disease. Meanwhile, advances in our understanding of molecular mechanisms have substantially advanced our treatment of patients with advanced lung cancer through the introduction of targeted therapies, immune approaches, improvements in chemotherapy, and better supportive care. However, the majority of these advances have occurred among patients with good functional status, normal organ function, and with the social and economic support systems to be able to benefit most from these treatments. The aim of this article is to bring greater attention to management of lung cancer in patients who are medically compromised, which remains a major barrier to care delivery. Impaired performance status is associated with poor outcomes and correlates with the high prevalence of cachexia among patients with advanced lung cancer. CT imaging is emerging as a research tool to quantify muscle loss in patients with cancer, and new therapeutics are on the horizon that may provide important adjunctive therapy in the future. The benefits of cancer therapy for patients with organ failure are poorly understood because of their exclusion from clinical trials. The availability of targeted therapy and immunotherapy may provide alternatives that may be easier to deliver in this population, but clinical trials of these new agents in this population are vital. Patients with lower socioeconomic status are disproportionately affected by lung cancer because of higher rates of tobacco addiction and the impact of socioeconomic status on delay in diagnosis, treatment, and outcomes. For all patients who are medically compromised with lung cancer, multidisciplinary approaches are particularly needed to evaluate these patients and to incorporate rapidly changing therapeutics to improve outcomes.

Perceptions of Lung Cancer and Smoking Among College Students in Jordan

A descriptive, cross-sectional design was adopted to identify college students’ knowledge and perceptions of lung cancer and smoking. A random sample of 400 students at the Jordan University of Science and Technology in northern Jordan was subjected to the Lung Cancer and Smoking Survey, which is based on the Health Belief Model. The results show that the prevalence of current smoking is 16.5% and that the prevalence of former smoking is 10.0%. Most (75.3%) of the respondents were aware of the prevalence of lung cancer. Almost all (90.3%) were aware of the cancer risk from air pollution, but fewer (57.5%) were concerned about the risk caused by side-stream smoke. Most disagreed that lung cancer could be easily cured. Former smokers were more knowledgeable than current smokers about the health hazards of smoking, and those who never smoked were more knowledgeable than both. Engineering students were more likely to agree with the benefits of quitting smoking than were medical or science students. Addiction and friends were the reasons most frequently given for not quitting smoking.

Age at occupational exposure to combustion products and lung cancer risk among men in Stockholm, Sweden

PURPOSE

Occupational exposure to combustion products rich in polycyclic aromatic hydrocarbons and particles is associated with an increased risk of lung cancer. This study aimed to evaluate whether the risk depended on the age at which the individuals were exposed.

METHODS

Data from 1042 lung cancer cases and 2364 frequency-matched population controls selected from all men aged 40-75 years residing in Stockholm County, Sweden, at any time between 1985 and 1990, included detailed questionnaire information on occupational, residential, and smoking history. Occupational exposures were assessed by an occupational hygienist, and exposure to air pollution from road traffic was estimated based on dispersion models.

RESULTS

We found that individuals exposed to combustion products in their twenties were at higher risk than those never exposed (adjusted OR = 1.46; 95% CI 1.02, 2.10). The association was still evident after adjusting for a number of potential confounders, including lifetime cumulative exposure and latency. No clear association was found in those exposed at older ages.

CONCLUSIONS

Exposure to combustion products at a young age was associated with elevated risk of lung cancer. Exposure-reduction programs should be aware of the susceptibility of the younger employees.

Polymorphisms in ERCC1 and ERCC2/XPD genes and carcinogen DNA adducts in human lung

OBJECTIVES

In this exploratory study, we aimed to investigate whether polymorphisms in excision repair cross-complementing group 1 (ERCC1) and excision repair cross-complementing group 2/xeroderma pigmentosum group D (ERCC2/XPD) in the nucleotide excision repair (NER) pathways associated with DNA adducts in human lung tissue. We also analyzed the association stratified by the major histologic subtypes of non-small cell lung cancer (NSCLC): adenocarcinoma (ADC) and squamous cell carcinoma (SQCC).

METHODS

The study population consisted of 107 early stage NSCLC patients from the Massachusetts General Hospital (MGH) in Boston who underwent curative surgical resection. Genotyping was completed for SNPs in ERCC1 [C8092A (rs3212986) and C118T (rs11615)] and ERCC2/XPD [Asp312Asn (rs1799793) and Lys751Gln (rs1052559)] using a PCR-RFLP method and the PCR with fluorescent allele-specific oligonucleotide probes (Taqman). DNA adduct levels were measured as relative adduct levels per 10(10) nucleotides by (32)P-postlabeling in non-tumor lung tissue.

RESULTS

After adjusting for potential confounders, lung DNA adduct levels increased by 103.2% [95% confidence interval (CI), -11.5 to 366.6] for ERCC2/XPD rs1799793AA genotype compared with their corresponding wild type homozygous genotypes in overall NSCLC, but the difference did not reach statistical significance. When we stratified by the subtypes of NSCLC, we found that DNA adducts levels in lung increased by 204.9% (95% CI, 0.8 to 822.2, P=0.059) for ERCC2/XPD rs1799793AA genotype in subjects with SQCC and the trend was statistically significant (P for trend=0.0489).

CONCLUSIONS

Polymorphisms in ERCC2/XPD Asp312Asn may be associated with increased DNA adduct levels in the lung, especially among subjects with SQCC. Further large scale studies are needed to confirm our findings.

Demography and histologic pattern of laryngeal squamous cell carcinoma in kenya

Background. Laryngeal squamous cell carcinoma is a common head and neck cancer worldwide. Objective. To determine the demographic characteristics of patients with laryngeal cancer, establish their tumor characteristics and relate it to their smoking and alcohol ingestion habits. Methods. Fifty cases and fifty controls were recruited of matching age, sex, and region of residence. History and pattern of cigarette smoking and alcohol ingestion was taken and analyzed. Results. 33 (66%) of the cases and 3 (6%) among controls were current cigarette smokers. 74% had smoked for more than 30 years, P < 0.0001 OR 21.3 (95% CI: 2.6-176.1). There was a male predominance (96%) and most cases (62%) were from the ethnic communities in the highland areas of Kenya predominantly in Central and Eastern provinces. Very heavy drinkers had increased risk of P < 0.0001 OR, 6.0 (95% CI: 1.957-18.398) and those who smoked cigarettes and drank alcohol had poorly differentiated tumors G3, P < 0.001, OR 11.652 (95% CI 2.305-58.895), and G4, P=0.52 OR 7.286 (95% CI 0.726-73.075). They also presented with advanced disease (73.6%). Conclusion. Cigarette smoking and alcohol ingestion are strong risk factors for development of late stage and poorly differentiated laryngeal squamous cell carcinoma in Kenya.

Distinct loci in the CHRNA5/CHRNA3/CHRNB4 gene cluster are associated with onset of regular smoking

Neuronal nicotinic acetylcholine receptor (nAChR) genes (CHRNA5/CHRNA3/CHRNB4) have been reproducibly associated with nicotine dependence, smoking behaviors, and lung cancer risk. Of the few reports that have focused on early smoking behaviors, association results have been mixed. This meta-analysis examines early smoking phenotypes and SNPs in the gene cluster to determine: (1) whether the most robust association signal in this region (rs16969968) for other smoking behaviors is also associated with early behaviors, and/or (2) if additional statistically independent signals are important in early smoking. We focused on two phenotypes: age of tobacco initiation (AOI) and age of first regular tobacco use (AOS). This study included 56,034 subjects (41 groups) spanning nine countries and evaluated five SNPs including rs1948, rs16969968, rs578776, rs588765, and rs684513. Each dataset was analyzed using a centrally generated script. Meta-analyses were conducted from summary statistics. AOS yielded significant associations with SNPs rs578776 (beta = 0.02, P = 0.004), rs1948 (beta = 0.023, P = 0.018), and rs684513 (beta = 0.032, P = 0.017), indicating protective effects. There were no significant associations for the AOI phenotype. Importantly, rs16969968, the most replicated signal in this region for nicotine dependence, cigarettes per day, and cotinine levels, was not associated with AOI (P = 0.59) or AOS (P = 0.92). These results provide important insight into the complexity of smoking behavior phenotypes, and suggest that association signals in the CHRNA5/A3/B4 gene cluster affecting early smoking behaviors may be different from those affecting the mature nicotine dependence phenotype.

Social inequality in health, responsibility and egalitarian justice

Are social inequalities in health unjust when brought about by differences in lifestyle? A widespread idea, luck egalitarianism, is that inequality stemming from individuals' free choices is not to be considered unjust, since individuals, presumably, are themselves responsible for such choices. Thus, to the extent that lifestyles are in fact results of free choices, social inequality in health brought about by these choices is not in tension with egalitarian justice. If this is so, then it may put in question the justification of free and equal access to health care and existing medical research priorities. However, personal responsibility is a highly contested issue and in this article we first consider the case for, and second the case against, personal responsibility for health in light of recent developments in philosophical accounts of responsibility and equality. We suggest-but do not fully establish-that at the most fundamental level people are never responsible in such a way that appeals to individuals' own responsibility can justify inequalities in health.

Changes in friends' and parental influences on cigarette smoking from early through late adolescence

PURPOSE

This study examined the changes in friends' and parental influences on cigarette smoking across two developmentally distinct social environments for adolescents: junior high school and high school.

METHODS

Longitudinal data consisting of seven repeated measures following 1,001 adolescents from 7th to 12th grade was obtained from the Midwestern Prevention Project. A two-piece Growth Curve Model (GCM) was used to assess the growth trajectory of current cigarette use: one piece for the junior high school period, and the other for the high school period. Perceived friends' and parental cigarette use were each used as a time-varying covariate in separate GCMs.

RESULTS

Effects of friends' and parental cigarette use remained significant on adolescent cigarette smoking across the two developmental periods. The magnitude of friends' effect was in general higher during junior high school than high school. The magnitude of the parental effect remained relatively stable between the two periods. However, decreasing trends in both effects were observed from 10th to 12th grade. Gender differences also emerged. Friends' and parental effects were greater for girls in their early high school years, whereas friends' effect decreased in magnitude among girls and increased among boys during high school.

CONCLUSIONS

The transition from junior high school to high school represents an opportunity for interventions to counteract peer influence given that such influence appeared to be much weaker during this period. However, interventions should continue to target parents as their behavior remains influential through the end of high school.

Effects of simvastatin and rosuvastatin on RAS protein, matrix metalloproteinases and NF-κB in lung cancer and in normal pulmonary tissues

OBJECTIVES

In this study, we have evaluated effects of 24-hour treatments with simvastatin or rosuvastatin on RAS protein, NF-κB and MMP expression in LC tissues obtained from 12 patients undergoing thoracic surgery.

MATERIALS AND METHODS

Normal and lung tumour tissues obtained from each sample were exposed to simvastatin (2.5-30 μm) or rosuvastatin (1.25-30 μm) and western blot analysis was then performed.

RESULTS

We documented increased expression of proteins, MMP-2, MMP-9 and NF-κB-p65 in LC tissues, with respect to normal tissues (P < 0.01). In the malignant tissues, simvastatin and rosuvastatin significantly (P < 0.01) and dose-dependently reduced RAS protein, MMP-2/9 and NF-κB-p65 expression.

CONCLUSIONS

In conclusion, our results suggest that simvastatin and rosuvastatin could play a role in LC treatment by modulation of RAS protein, MMP-2/9 and NF-κB-p65.

Cigarette smoking and alcohol ingestion as risk factors for laryngeal squamous cell carcinoma at kenyatta national hospital, kenya

Laryngeal squamous cell carcinoma (SCC) is strongly linked to cigarette smoking. It is estimated to account for more than 70% of laryngeal SCCs and up to 89% in combination with alcohol. We wished to determine the prevalence of cigarette smoking and alcohol ingestion among patients with laryngeal squamous cell carcinoma and estimate risk attributed to cigarette smoking and alcohol ingestion. Fifty experimental group patients and fifty controls were recruited of matching age, sex and region of residence. History of smoking and alcohol intake was taken and analyzed to estimate the relative strengths of these exposures. Cessation of smoking was associated with reduced risk of SCC. Smokers had increased risk compared to controls. Those who smoked only had a higher glottic cancer risk. Those who smoked and drank alcohol had a higher supraglottic cancer risk. Being a current smoker and long duration of smoking were independent risk factors of laryngeal SCC.

Genetic polymorphism of drug metabolizing enzymes (GSTM1 and CYP1A1) as risk factors for oral premalignant lesions and oral cancer

AIMS

Polymorphisms in the genes that code for metabolic enzymes involved in either the activation (Phase I) or detoxication (Phase II) of chemical carcinogens in tobacco, may alter expression or function of carcinogenic compounds and hence alter risk of oral cancer. The present study investigates whether polymorphisms at CYP1A1 and GSTM1 gene loci act as risk factors for oral precancerous lesions and cancer.

METHODS

For the present study, histopathologically confirmed cases of 90 oral precancerous lesions, 150 oral squamous cell carcinoma (SCC) and 150 control subjects were selected. Polymerase chain reaction and restriction fragment length polymorphism were performed using DNA from blood samples to determine the polymorphic genotypes at CYP1A1 and GSTM1 loci.

RESULTS

CYP1A1 C (m2/m2) genotype conferred a 12.0 fold-increased risk (OR=12.0; 95% CI, 2.40-60.05) to oral SCC. GSTM1 null showed no significant association but the frequency was higher in oral SCC cases. Patients with genotype C and/or GSTM1 deficiency developed carcinoma after less tobacco consumption than those of other genotypes though the difference was not statistically significant. The frequency of the combined genotypes C and GSTM1 null was found to be 14% among oral SCC patients. On comparing the susceptibility of intraoral sites it was found that in the majority of cases (64%) in the study groups they were the buccal mucosa.

CONCLUSION

Hence it was concluded that metabolic enzymes reported in the present study: CYP1A1 significantly alter oral cancer risk. GSTM1 null and CYP1A1 C (m2m2) show a predisposition to premalignant lesions and cancer of the buccal mucosa than other sites.

Cigarette Smoking and Lung Cancer: Pediatric Roots

A vast array of data suggests that early age of smoking onset enhances the risk for development of lung cancer in adulthood. Initiation of smoking at a young age may influence the development of lung cancer because of its effect on duration of smoking. Early onset of smoking also may serve as an independent risk factor. It may increase the likelihood that smoking occurs during a critical period of development that enhances susceptibility to the adverse effects of cancer causing agents in cigarette smoke, thereby facilitating the initiation of the carcinogenic process. While evidence for the latter hypothesis derives from a variety of sources, definitive proof has proven elusive. Whether or not early age of smoking serves as an independent risk factor for lung carcinogenesis, the consensus of the public health community is that prevention of smoking onset at a young age and early cessation are keys to stemming the current lung cancer pandemic. Population approaches to tobacco prevention and control, such as measures contained in the World Health Organization Framework Convention Tobacco Control Treaty, offer the best opportunity, on the scale needed, to create a smoke-free world and bring an end to the pandemic of tobacco-related disease.

Key epigenetic changes associated with lung cancer development: results from dense methylation array profiling

Epigenetic alterations are a common event in lung cancer and their identification can serve to inform on the carcinogenic process and provide clinically relevant biomarkers. Using paired tumor and non-tumor lung tissues from 146 individuals from three independent populations we sought to identify common changes in DNA methylation associated with the development of non-small cell lung cancer. Pathologically normal lung tissue taken at the time of cancer resection was matched to tumorous lung tissue and together were probed for methylation using Illumina GoldenGate arrays in the discovery set (n = 47 pairs) followed by bisulfite pyrosequencing for validation sets (n = 99 pairs). For each matched pair the change in methylation at each CpG was calculated (the odds ratio), and these ratios were averaged across individuals and ranked by magnitude to identify the CpGs with the greatest change in methylation associated with tumor development. We identified the top gene-loci representing an increase in methylation (HOXA9, 10.3-fold and SOX1, 5.9-fold) and decrease in methylation (DDR1, 8.1-fold). In replication testing sets, methylation was higher in tumors for HOXA9 (p < 2.2 × 10 (-16) ) and SOX1 (p < 2.2 × 10 (-16) ) and lower for DDR1 (p < 2.2 × 10 (-16) ). The magnitude and strength of these changes were consistent across squamous cell and adenocarcinoma tumors. Our data indicate that the identified genes consistently have altered methylation in lung tumors. Our identified genes should be included in translational studies that aim to develop screening for early disease detection.

Improving media message interpretation processing skills to promote healthy decision making about substance use: the effects of the middle school media ready curriculum

The Media Ready Program was designed as a middle school, media literacy education, preventive intervention program to improve adolescents' media literacy skills and reduce their intention to use alcohol or tobacco products. In a short-term efficacy trial, schools in North Carolina were randomly assigned to conditions (Media Ready: n = 214; control: n = 198). Boys in the Media Ready group reported significantly less intention to use alcohol in the future than did boys in the control group. Also, students in the Media Ready group who had used tobacco in the past reported significantly less intention to use tobacco in the future than did students in the control group who had previously used tobacco. Multilevel multiple mediation analyses suggest that the set of logical analysis Message Interpretation Processing variables mediated the program's effect on students' intentions to use alcohol or tobacco in the future.

Biomarkers for oxidative stress in acute lung injury induced in rabbits submitted to different strategies of mechanical ventilation

Oxidative damage has been said to play an important role in pulmonary injury, which is associated with the development and progression of acute respiratory distress syndrome (ARDS). We aimed to identify biomarkers to determine the oxidative stress in an animal model of acute lung injury (ALI) using two different strategies of mechanical ventilation. Rabbits were ventilated using either conventional mechanical ventilation (CMV) or high-frequency oscillatory ventilation (HFOV). Lung injury was induced by tracheal saline infusion (30 ml/kg, 38°C). In addition, five healthy rabbits were studied for oxidative stress. Isolated lymphocytes from peripheral blood and lung tissue samples were analyzed by alkaline single cell gel electrophoresis (comet assay) to determine DNA damage. Total antioxidant performance (TAP) assay was applied to measure overall antioxidant performance in plasma and lung tissue. HFOV rabbits had similar results to healthy animals, showing significantly higher antioxidant performance and lower DNA damage compared with CMV in lung tissue and plasma. Total antioxidant performance showed a significant positive correlation (r = 0.58; P = 0.0006) in plasma and lung tissue. In addition, comet assay presented a significant positive correlation (r = 0.66; P = 0.007) between cells recovered from target tissue and peripheral blood. Moreover, antioxidant performance was significantly and negatively correlated with DNA damage (r = -0.50; P = 0.002) in lung tissue. This study indicates that both TAP and comet assay identify increased oxidative stress in CMV rabbits compared with HFOV. Antioxidant performance analyzed by TAP and oxidative DNA damage by comet assay, both in plasma, reflects oxidative stress in the target tissue, which warrants further studies in humans.

MTHFR polymorphisms, folate intake and carcinogen DNA adducts in the lung

The methylenetetrahydrofolate reductase (MTHFR) genes and folate in one-carbon metabolism are essential for DNA methylation and synthesis. However, their role in carcinogen DNA damage in target lung tissue, a dosimeter for cancer risk, is not known. Our study aimed to investigate the association between genetic and nutritional one-carbon metabolism factors and DNA adducts in target lung. Data on 135 lung cancer cases from the Massachusetts General Hospital were studied. Genotyping was completed for MTHFR C677T (rs1801133) and A1298C (rs1801131). Information on dietary intake for one-carbon related micronutrients, folate and other B vitamin was derived from a validated food frequency questionnaire. DNA adducts in lung were measured by (32) P-postlabeling. After adjusting for potential confounders, DNA adduct levels in lung significantly increased by 69.2% [95% confidence interval (CI), 5.5% to 171.5%] for the MTHFR 1298AC+CC genotype. The high risk group, combining the A1298C (AC+CC) plus C677T (CT+TT) genotypes, had significantly enhanced levels of lung adducts by 210.7% (95% CI, 21.4% to 695.2%) in contrast to the A1298C (AA) plus C677T (CC) genotypes. Elevation of DNA adduct was pronounced-111.3% (95% CI, -3.0 to 360.5%) among 1298AC+CC patients, who consumed the lowest level of folate intake as compared to 1298AA individuals with highest tertile of intake. These results indicate that DNA adducts levels are influenced by MTHFR polymorphisms and low folate consumption, suggesting an important role of genetic and nutritional factors in protecting DNA damage from lung carcinogen in at-risk populations.

Impacts of early smoking initiation: long-term trends of lung cancer mortality and smoking initiation from repeated cross-sectional surveys in Great Britain

OBJECTIVE

To show long-term trends of smoking initiation in Great Britain including unanalysed data and assess the impact of early smoking initiation on the lung cancer mortality in later ages focusing on birth cohorts.

DESIGN

Reanalysis of repeated cross-sectional surveys conducted 13 times during 1965-1987.

SETTING

Great Britain.

PARTICIPANTS

Men and women aged 16 years and over in each survey.

PRIMARY OUTCOME MEASURES

Smoking initiation for 1898-1969 birth cohorts and lung cancer mortality in 1950-2009.

RESULTS

In men, 1900-1925 birth cohorts showed high smoking initiation (>32%, >50% and >80% at 15, 17 and 29 years old, respectively). Correspondingly, the lung cancer mortality in these cohorts exceeded 1 per 1000 at a young age (50-54 years old). In women, smoking initiation increased clearly from the 1898 cohort to the 1925 cohort (2% to 12%, 4% to 24%, and 13% to 54% at 15, 17 and 29 years old, respectively). Correspondingly, the age at which the mortality exceeded 1 per 1000 became younger (75-79 to 60-64 years old). In both men and women, short-term decreases in initiation were seen from the late-1920s cohorts. Correspondingly, lung cancer mortality decreased. In women, initiation increased again after the mid-1930s cohorts, and mortality increased after they became 60-64 years old.

CONCLUSIONS

Clear relationships between smoking initiation and lung cancer mortality across birth cohorts were observed. Countries with rapid increases in initiation in teens should not underestimate the risk in the distant future. Because of the long time lags within cohorts compared with rapid changes in smoking habits across cohorts, age-specific measures focusing on birth cohorts should be monitored.

Biological monitoring of carcinogens: current status and perspectives

Biomonitoring exposures to carcinogens is common practice and a variety of biomarkers have been developed to assess both exposures and biochemical/biological effects. However, their clinical and preventive relevance is still uncertain. The understanding of cancer as a genetic disease has dramatically evolved during last decades, showing that cancer cell types acquire their characteristics with different strategies, time frames and microenvironments. Therefore, the place of current biomarkers within this complex scenario of gene-environment interactions leading to cancer cannot be defined. Reasons are manifold. Most studies assessed cancer risk on a group basis through snapshots taken at unknown time-points of the postulated chain of events. Little attention has been paid to the variety and variability of exposures, and no prospective study validated the indicators of biochemical/biological effects. New opportunities and suggestions for biomonitoring exposures to carcinogens could derive from exploring the exposome that combines exposures from all sources both external and internal. The discovery of new biomarkers and the identification of relevant gene-specific pathways could be achieved through metabolomic and genome-wide studies. In conclusion, it is possible to envisage personalized biomonitoring procedures, such as those already implemented in the context of nutrition and clinical oncology.

Cigarette experimentation in Mexican origin youth: psychosocial and genetic determinants

BACKGROUND

Established psychosocial risk factors increase the risk for experimentation among Mexican origin youth. Now, we comprehensively investigate the added contribution of select polymorphisms in candidate genetic pathways associated with sensation seeking, risk taking, and smoking phenotypes to predict experimentation.

METHODS

Participants (N = 1,118 Mexican origin youth) recruited from a large population-based cohort study in Houston, TX, provided prospective data on cigarette experimentation over 3 years. Psychosocial data were elicited twice-baseline and final follow-up. Participants were genotyped for 672 functional and tagging variants in the dopamine, serotonin, and opioid pathways.

RESULTS

After adjusting for gender and age, with a Bayesian False Discovery Probability set at 0.8 and prior probability of 0.05, six gene variants were significantly associated with risk of experimentation. After controlling for established risk factors, multivariable analyses revealed that participants with six or more risk alleles were 2.25 [95% confidence interval (CI), 1.62-3.13] times more likely to have experimented since baseline than participants with five or fewer. Among committed never-smokers (N = 872), three genes (OPRM1, SNAP25, HTR1B) were associated with experimentation as were all psychosocial factors. Among susceptible youth (N = 246), older age at baseline, living with a smoker, and three different genes (HTR2A, DRD2, SLC6A3) predicted experimentation.

CONCLUSIONS

Our findings, which have implications for development of culturally specific interventions, need to be validated in other ethnic groups.

IMPACT

These results suggest that variations in select genes interact with a cognitive predisposition toward smoking. In susceptible adolescents, the impact of the genetic variants appears to be larger than committed never-smokers.

Knowledge about the relationship between smoking and blindness in Canada, the United States, the United Kingdom, and Australia: results from the International Tobacco Control Four-Country Project

PURPOSE

Smoking is causally associated with certain prevalent visually impairing eye diseases, including age-related macular degeneration and cataract. Studies have found that people are afraid of "going blind" and may be motivated to quit smoking if they know that vision loss is associated with smoking behavior.

METHODS

A random-digit dialed telephone survey was used to measure health knowledge of adult smokers in Canada (n = 2,765), the United States (n = 3,178), the United Kingdom (n = 2,767), and Australia (n = 2,623) as part of the International Tobacco Control Four-Country Project.

RESULTS

A low proportion of smokers from Canada (13.0%), the United States (9.5%), and the United Kingdom (9.7%) believed that smoking can cause blindness. In contrast, 47.2% of Australian smokers believed that smoking causes blindness. Australia was the only country during the sampling period to have national awareness campaigns about smoking and its effects on eye health.

CONCLUSION

These findings point to the need across countries to educate the public on this important consequence of smoking. There is an opportunity for the public health and eye health communities to work to educate the public about the impacts smoking has on eye health to improve quit rates and help discourage people from starting to smoke.

Effects of individual characteristics and school environment on cigarette smoking among students ages 13-15: A multilevel analysis of the 2007 Global Youth Tobacco Survey (GYTS) data from Vietnam

This paper aims to estimate the prevalence of cigarette smoking among students in Vietnam ages 13-15 and examines its relationship with compositional and contextual factors. The data used in this paper were obtained from the 2007 Global Youth Tobacco Survey conducted in nine provinces in Vietnam. A multilevel logistic regression model was applied to analyse the association between the current incidence of cigarette smoking and factors on both the individual and school level. The prevalence of cigarette smoking among students was 3.3% overall. The prevalence of smoking among male students (5.9%) was higher than that among females (1.2%). Parental smoking was a significant risk factor for smoking among the students. Having a friend who smoked was the strongest predictor of smoking status among the study subjects. We have demonstrated that school-level factors appeared to impact the prevalence of cigarette smoking among students ages 13-15. This paper highlights the importance of utilising an extensive range of actions to prevent students from using tobacco in Vietnam. These actions should include providing specific curricula for students that address both individual characteristics and the school environment. Further, prevention programmes should also target both parental- and peer-smoking issues.

Smoking initiation is followed by the early acquisition of epigenetic change in cervical epithelium: a longitudinal study

BACKGROUND

To prove a causal link between an epigenetic change and an environmental or behavioural risk factor for a given disease, it is first necessary to show that the onset of exposure precedes the first detection of that epigenetic change in subjects who are still free of disease.

METHODS

Towards this end, a cohort of women aged 15-19 years, recruited soon after they first had sexual intercourse, were used to provide sequential observations on the relationship between cigarette smoking and the detection in cervical cytological samples of methylated forms of CDKN2A (p16) using nested methylation-specific polymerase chain reaction.

RESULTS

Among women who remained cytologically normal and who tested negative for human papillomavirus DNA in cervical smears during follow-up, those who first started to smoke during follow-up had an increased risk of acquiring CDKN2A methylation compared with never-smokers (odds ratio=3.67; 95% confidence interval 1.09-12.33; P=0.04).

CONCLUSION

Smoking initiation is associated with the appearance of methylated forms of CDKN2A.

Exposure to environmental tobacco smoke in childhood and incidence of cancer in adulthood in never smokers in the European Prospective Investigation into Cancer and Nutrition

The association between childhood environmental tobacco smoke (ETS) exposure and adult cancer risk is controversial; we examined this relationship in never smokers within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Over an average of 10 years, 8,372 cases of cancer were diagnosed in 112,430 never smokers in EPIC. Childhood ETS was self-reported by participants at baseline, along with other lifestyle factors. Hazard ratios (HR) for ETS exposure in childhood and their 95% confidence intervals (CI) were estimated by Cox proportional hazards models stratified by age, sex, and study center and adjusted for education, alcohol drinking, body mass index, physical activity, non-alcoholic energy intake, fruit and vegetable intake, and adulthood ETS exposure. Models were further adjusted for reproductive factors for female cancers, for meat intake for digestive system cancers, and for diabetes status for pancreatic cancer. No association was observed between childhood ETS exposure and overall cancer risks (HR = 0.97, 95% CI = 0.92-1.02), and for selected sites. The only exception was pancreatic cancer, as previously reported by Vrieling et al., among those who had been exposed daily in childhood (overall HR = 2.09, 95% CI = 1.14-3.84). In conclusion, childhood ETS exposure might not be a major risk factor for common cancers in adulthood.

The effect of smoking on the risk of lung cancer mortality for asbestos workers in Great Britain (1971-2005)

OBJECTIVES

Workers in the asbestos industry tend to have high smoking rates compared to the general population. Both asbestos exposure and cigarette smoking are recognized risk factors for lung cancer mortality, but the exact nature of the interaction between the two remains uncertain. The aim of this study was to examine the effect of smoking and smoking cessation among asbestos workers in Great Britain (GB) and investigate the interaction between asbestos exposure and smoking.

METHODS

The study population consisted of 98 912 asbestos workers recruited into the GB Asbestos Survey from 1971, followed-up to December 2005. Poisson regression was used to estimate relative risks of lung cancer mortality associated with smoking habits of the asbestos workers and to assess whether these effects differed within various categories of asbestos exposure. The interaction between asbestos exposure and smoking was examined using the Synergy (S) and Multiplicativity (V) indices, which test the hypotheses of additive and multiplicative interaction, respectively. The proportion of lung cancers among smokers attributable to the interaction of asbestos and smoking was also estimated.

RESULTS

During 1 780 233 person-years of follow-up, there were 1878 deaths from lung cancer (12% of all deaths). Risk of lung cancer mortality increased with packs smoked per day, smoking duration, and total smoke exposure (pack-years). Asbestos workers who stopped smoking remained at increased risk of lung cancer mortality up to 40 years after smoking cessation compared to asbestos workers who never smoked. The effects of smoking and stopping smoking did not differ by duration of asbestos exposure, main occupation, age at first asbestos exposure, year of first exposure, or latency period. The interaction between asbestos exposure and smoking for asbestos workers was greater than additive [S 1.4, 95% confidence interval (CI) 1.2-1.6], and the multiplicative hypothesis could not be rejected (V 0.9, 95% CI 0.3-2.4). For those asbestos workers who smoked, an estimated 26% (95% CI 14-38%) of lung cancer deaths were attributable to the interaction of asbestos and smoking.

CONCLUSIONS

This study emphasizes the importance of smoking prevention and cessation among those who work in the asbestos industry.

Protective effects of selenium against DNA adduct formation in Inuit environmentally exposed to PCBs

Dietary habits that expose populations to potential toxicants as well as protective agents simultaneously are a realistic scenario where a meaningful assessment of the interactions and net benefit or damage can be made. A group of Inuit from Salluit, Northern Canada are exposed to high levels of PCBs and selenium, both present in the Inuit traditional foods such as blubber from sea mammals and fatty fish. Blood samples were collected from 83 Inuit, 22-70 years old. Blood selenium and PCB levels were determined previously and ranged from 227 to 2069µg/L and 1.7 to 143µg/L, respectively. DNA isolated from white blood cells were analyzed by modified (32)P-postlabeling adductomics technology that detects a multitude of highly polar to lipophilic adducts. The levels of 8-oxodG adducts ranged from 470 to 7400 adducts/10(9) nucleotides. Other as yet unidentified polar adducts showed a 30 to 800-fold inter-individual variability. Adduct levels were negatively associated with PCB and selenium levels. The subjects were classified into high and low ratio groups, with respect to selenium/PCB. In the high ratio group, the coefficient of selenium is significantly negatively correlated with 8-oxodG (r = -0.38, p = 0.014) and total adducts (r = -0.41, p = 0.009) while there was no correlation within the low selenium/PCB group. This study suggests that increasing selenium has mitigating effect in reducing DNA adducts and therefore, possible negative effects of PCB were not seen. A protective effect of selenium is highlighted.

Genetic modifiers of carcinogen DNA adducts in target lung and peripheral blood mononuclear cells

Measurement of carcinogen DNA adducts in blood has been used as a surrogate for the target lung tissue. We aimed to examine whether genetic polymorphisms in several metabolic pathway genes modify the relation between DNA adducts in target lung and blood. One hundred and thirty-five early-stage lung cancer patients from the Massachusetts General Hospital were studied. DNA adducts were measured by the (32)P-postlabeling assay in lung and blood mononuclear cells (MNCs) in a subset of 53 who had paired blood samples. Single-nucleotide polymorphisms (SNPs) were assessed in genes involved in phase II (GSTs, NAT2, EPHX and NQO1), DNA repair (ERCC1, ERCC2 and XRCC1) and DNA methylation (MTHFR C677T and A1298C) pathways. There was a significant correlation between DNA adduct levels in lung and blood within the different genotypes, with one exception. Significant modifications in adducts were found by variants in genes for phase II metabolism [NAT2 (1.51 for rapid versus 0.76 for slow, P = 0.022)], DNA repair [ERCC1 C118T (P = 0.014), ERCC2 (P = 0.003) and XRCC1 (P = 0.025)] and MTHFR [C677T (P = 0.005) and A1298C (P = 0.005)]. The relation between DNA adducts in blood MNCs and target lung tissue was significantly modified by the single-nucleotide polymorphisms in the three main pathways. Despite the relatively small sample size, our results suggest that genetic factors may need to be considered when assessing the association of DNA adducts using surrogate tissue in studies of lung cancer. Further studies are needed to better understand their role and the mechanisms.

Smoking, DNA adducts and number of risk DNA repair alleles in lung cancer cases, in subjects with benign lung diseases and in controls

Smoke constituents can induce DNA adducts that cause mutations and lead to lung cancer. We have analyzed DNA adducts and polymorphisms in two DNA repair genes, for example, XRCC1 Arg194Trp and Arg399Gln genes and XRCC3 Thr241Met gene, in 34 lung cancer cases in respect to 30 subjects with benign lung cancer disease and 40 healthy controls. When the study population was categorized in base to the number of risk alleles, adducts were significantly increased in individuals bearing 3-4 risk alleles (OR = 4.1 95% C.I. 1.28-13.09, P = .009). A significant association with smoking was noticed in smokers for more than 40 years carrying 3-4 risk alleles (OR = 36.38, 95% C.I. 1.17-1132.84, P = .040). A not statistically significant increment of lung cancer risk was observed in the same group (OR = 4.54, 95% C.I. 0.33-62.93, P = .259). Our results suggest that the analysis of the number of risk alleles predicts the interindividual variation in DNA adducts of smokers and lung cancer cases.

Predictors of age at onset of tobacco and cannabis use in Danish adolescents

INTRODUCTION

Early onset of tobacco and cannabis use predicts later substance abuse and risk behaviour and has large health consequences.

OBJECTIVES

The aim of this study was to examine risk factors for the age at onset of smoking and cannabis use among a group of Danish children between 7 years and 18 years of age.

METHODS

Four hundred and eighty randomly selected children and their parents participated in a study about the prevalence of asthma. The study included questions about alcohol, tobacco and cannabis use. The children were interviewed face-to-face while the parents answered a questionnaire.

RESULTS

The age at onset of daily smoking was significantly associated with the adolescents' tendency to binge drink [hazard ratio 4.78, 95% confidence interval (CI) (1.85-12.34), P = 0.001) and to use hard drugs [hazard ratio 2.81, 95% CI (1.03-7.78), P = 0.047], whereas the age at onset of cannabis use was significantly associated with binge drinking [hazard ratio 3.29, 95% CI (1.51-7.20), P = 0.003] and cigarette smoking [hazard ratio 2.51, 95% CI (1.26-5.00), P = 0.009]. There were no significant effect of the parents' smoking and alcohol habits, their socioeconomic or marital status on the adolescent' age at onset of smoking or cannabis.

CONCLUSION

This study shows a close connection between adolescent tobacco and cannabis use and alcohol habits. Knowledge of this is important when planning future prevention strategies.

Duration of exposure to environmental carcinogens affects DNA-adduct level in human lymphocytes

BACKGROUND AND OBJECTIVE

An important issue in human biomonitoring is determining how exposure duration affects the kinetics of molecular biomarkers. In this study we compare the influence of exposure variables on DNA adducts.

METHODS

DNA adducts were analysed by 32P-postlabelling in lympho/monocytes of 677 Caucasian subjects.

RESULTS

After correction for other variables, DNA adducts increased depending on the length of occupational and smoke exposures. Higher DNA adducts were detected in workers with more than 14 years of exposure than in workers with shorter exposures (RR = 1.19, p = 0.049) and in smokers with more than 10 years of exposure than in smokers with shorter exposure (RR = 1.21, p <0.001).

CONCLUSIONS

Exposure length is the primary factor affecting DNA-adduct level in lympho/monocytes both in smokers and in occupationally exposed subjects.

Rapid method for determination of DNA repair capacity in human peripheral blood lymphocytes amongst smokers

Background

DNA repair capacity is an important determinant of susceptibility to cancer. The hOGG1 enzyme is crucial for repairing the 8-oxoguanine lesion that occurs either as a byproduct of oxidative metabolism or as a result of exogenous sources such as exposure to cigarette smoke. It has been previously reported that smokers with low hOGG1 activity had significantly higher risk of developing lung cancer as compared to smokers with high hOGG1 activity.

Methods

In the current study we elucidate the association between plasma levels of 8-OHdG and the OGG1 repair capacity. We used the commercially available 8-OHdG ELISA (enzyme-linked immunosorbent assay), the Comet assay/FLARE hOGG1 (Fragment Length Analysis by Repair Enzymes) assay for quantification of the levels of 8-OHdG and measured the constitutive, induced and unrepaired residual damage, respectively. We compared the DNA repair capacity in peripheral blood lymphocytes following H₂O₂ exposure in 30 lung cancer patients, 30 non-, 30 former and 30 current smoker controls matched by age and gender.

Results

Our results show that lung cancer cases and current smoker controls have similar levels of 8-OHdG lesions that are significantly higher compared to the non-smokers controls. However, lung cancer cases showed significantly poorer repair capacity compared to all controls tested, including the current smokers controls. After adjustment for age, gender and family history of smoking-related cancer using linear regression, we observed a 5-fold increase in risk of lung cancer associated with high levels of residual damage/reduced repair capacity. Reduced OGG1 activity could be expected to be a risk factor in other smoking-related cancers.

Conclusion

Our study shows that the Comet/FLARE assay is a relatively rapid and useful method for determination of DNA repair capacity. Using this assay we could identify individuals with high levels of residual damage and hence poor repair capacity who would be good candidates for intensive follow-up and screening.

Synergistic effects of NAT2 slow and GSTM1 null genotypes on carcinogen DNA damage in the lung

BACKGROUND

Polymorphisms in carcinogen detoxification enzymes, NAT2 and GSTM1, have been suggested as susceptibility factors for DNA damage and lung cancer. However, little information is available on DNA adduct burden in the lung tissue and polymorphisms in NAT2 and GST genes. We investigated the independent and combined effects of the metabolic gene polymorphisms of NAT2 and GSTs on DNA adduct formation in different tissues (lung and blood) in lung cancer patients.

METHODS

DNA adducts were measured in lung and blood by the (32)P-postlabeling assay. Multiple regression models were used to assess adjusted percent change in DNA adduct levels associated with GST and NAT2 genotypes.

RESULTS

After adjusting for potential confounders, as well as for other GST gene variants, lung adduct levels significantly increased by 150.3% [95% confidence interval (95% CI), 35.4-362.6%] for the GSTM1 null and by 73.9% (95% CI, -3.2% to 212.4%) for the NAT2 slow acetylator genotype, respectively. No association was seen with polymorphisms of other GST genes such as GSTT1 and GSTP1. The high-risk group, the combined GSTM1 null plus NAT2 slow, had significantly enhanced levels of lung adducts by 295% (95% CI, 72.7-803.5%) over those associated with single genes, suggesting a synergistic effect on DNA damage in the target lung tissue.

CONCLUSIONS

The increase in DNA adduct levels in lung is associated with the GSTM1 null and NAT2 slow genotypes alone or in combination.

IMPACT

These results suggest that GSTM1 and NAT2 genotypes play an independent and interactive role in the formation of carcinogen DNA adduct in the lung.

Women and tobacco dependence

Millions of American girls and women have been drawn to smoking by an industry that has been clearly and systematically targeting women of all ages and life circumstances. Tobacco marketing strategies skillfully link cigarette use to typical female values. Biologically speaking, women are especially vulnerable to the legion of health problems of tobacco use. Smoking is a critical hazard for women in their reproductive years, particularly when they are pregnant.

White blood cell DNA adducts in a cohort of asthmatic children exposed to environmental tobacco smoke

Purpose

Exposure to environmental tobacco smoke (ETS) leads to molecular damage in the form of DNA adducts. While lung cancer risk is higher among African Americans compared to White Americans, a few studies have tested for racial differences in DNA adducts among children exposed to ETS. The purpose of this study was to test whether African American children have higher DNA adducts levels compared to White children adjusted for ETS exposure.

Methods

Data and biologic specimens were drawn from an existing cohort of 212 asthmatic children. These subjects participated in a 12-month ETS-reduction trial that employed HEPA air cleaners with active filter cartridges and sham filter cartridges. White blood cell (WBC) DNA was analyzed for DNA adducts using ³²P-postlabeling. We assessed ETS exposure using a validated air nicotine dosimeter. We determined the independent relationship between African American race and DNA adduct levels adjusted for ETS exposure and air cleaner use.

Results

The mean age of the subjects was 8.4 years; 55% were African American. There was no difference in DNA adduct levels between African American and White children (11.8 vs. 11.2 adducts per 10⁹ nucleotides, p = 0.86), despite slightly higher levels of air nicotine exposure (3.4 vs. 2.2 μg/m³, p = 0.14). African American children used their air cleaners less often than White children. We found that the best predictor of DNA adduct levels was the duration of air cleaner use (r = −0.133, p = 0.056). This association was independent of cartridge type.

Conclusions

We did not see differences in adduct levels by race even after accounting for the level of ETS exposure. However, there was a marginal inverse association between air cleaner use and adducts. Additional research is required to understand this phenomenon.