Environmental tobacco smoke, genetic susceptibility, and risk of lung cancer in never-smoking women

The interplay between autophagy and apoptosis: its implication in lung cancer and therapeutics

Maintaining cellular homeostasis relies on the interplay between apoptosis and autophagy, and disruption in either of these processes can contribute to the development of cancer. Autophagy can hinder the apoptotic process, and when autophagy is inhibited in such instances, it can enhance the rate of apoptosis. However, evidence suggests that excessive autophagy can also lead to apoptotic cell death. Also, excess autophagy can cause excessive digestion of cellular organelles, causing autophagic cell death. Targeting autophagy in non-small cell lung cancer (NSCLC), the most common form of lung cancer, can be very tricky due to the dual nature of autophagy. According to genetic analysis, various mutations in p53 and EGFR, G:C to A:T transversions seem responsible for the development of lung cancer in smokers and non-smokers. These events trigger cytoprotective autophagy or induce apoptotic cell death through different but interconnected signalling pathways. Lung cancer being the leading cause of death worldwide, calls for more attention to disease prognosis and new therapeutics in the market. However, molecules responsible for autophagy to apoptosis transition are yet to be studied elaborately. Also, the role of effector caspases during this shift needs to be elucidated in future. To comprehend how therapeutics operate through the modulation of autophagy and apoptosis and to target such pathways, it is crucial to emphasize these intricate connections. Many therapeutics discussed in this review targeting both apoptosis and autophagy have shown promising results in vitro and in vivo, however, few have crossed the hurdles of clinical trial. Nevertheless, the quest for safer and better efficacious agents is still alive, with the sole aim to develop novel cancer chemotherapeutic(s).

Why Female Smokers Have Poorer Long-Term Health Outcomes than Male Smokers: The Role of Cigarette Smoking During Pregnancy

Objectives: Women's health status is better than men but the opposite is true for female smokers who usually have poorer long-health outcomes than male smokers. The objectives of this study were to thoroughly reviewed and analyzed relevant literature and to propose a hypothesis that may explain this paradox phenomenon. Methods: We conducted a search of literature from three English databases (EMBASE, MEDLINE, and Google Scholar) from inception to 13 November 2023. A combination of key words and/or subject headings in English was applied, including relevant terms for cigarette smoking, sex/gender, pregnancy, and health indicators. We then performed analysis of the searched literature. Results: Based on this review/analysis of literature, we proposed a hypothesis that may explain this paradox phenomenon: female smokers have worse long-term health outcomes than male smokers because some of them smoke during pregnancy, and the adverse effects of cigarette smoking during pregnancy is much stronger than cigarette smoking during non-pregnancy periods. Conclusion: Approval of our pregnancy-amplification theory could provide additional evidence on the adverse effect on women's long-term health outcomes for cigarette smoking during pregnancy.

Lung cancer in patients who have never smoked - an emerging disease

Lung cancer is the most common cause of cancer-related deaths globally. Although smoking-related lung cancers continue to account for the majority of diagnoses, smoking rates have been decreasing for several decades. Lung cancer in individuals who have never smoked (LCINS) is estimated to be the fifth most common cause of cancer-related deaths worldwide in 2023, preferentially occurring in women and Asian populations. As smoking rates continue to decline, understanding the aetiology and features of this disease, which necessitate unique diagnostic and treatment paradigms, will be imperative. New data have provided important insights into the molecular and genomic characteristics of LCINS, which are distinct from those of smoking-associated lung cancers and directly affect treatment decisions and outcomes. Herein, we review the emerging data regarding the aetiology and features of LCINS, particularly the genetic and environmental underpinnings of this disease as well as their implications for treatment. In addition, we outline the unique diagnostic and therapeutic paradigms of LCINS and discuss future directions in identifying individuals at high risk of this disease for potential screening efforts.

Second Primary Lung Cancer Among Lung Cancer Survivors Who Never Smoked

Importance

Lung cancer among never-smokers accounts for 25% of all lung cancers in the US; recent therapeutic advances have improved survival among patients with initial primary lung cancer (IPLC), who are now at high risk of developing second primary lung cancer (SPLC). As smoking rates continue to decline in the US, it is critical to examine more closely the epidemiology of lung cancer among patients who never smoked, including their risk for SPLC.

Objective

To estimate and compare the cumulative SPLC incidence among lung cancer survivors who have never smoked vs those who have ever smoked.

Design, Setting, and Participants

This population-based prospective cohort study used data from the Multiethnic Cohort Study (MEC), which enrolled participants between April 18, 1993, and December 31, 1996, with follow-up through July 1, 2017. Eligible individuals for this study were aged 45 to 75 years and had complete smoking data at baseline. These participants were followed up for IPLC and further SPLC development through the Surveillance, Epidemiology, and End Results registry. The data were analyzed from July 1, 2022, to January 31, 2023.

Exposures

Never-smoking vs ever-smoking exposure at MEC enrollment.

Main Outcomes and Measures

The study had 2 primary outcomes: (1) 10-year cumulative incidence of IPLC in the entire study cohort and 10-year cumulative incidence of SPLC among patients with IPLC and (2) standardized incidence ratio (SIR) (calculated as the SPLC incidence divided by the IPLC incidence) by smoking history.

Results

Among 211 414 MEC participants, 7161 (3.96%) developed IPLC over 4 038 007 person-years, and 163 (2.28%) developed SPLC over 16 470 person-years. Of the participants with IPLC, the mean (SD) age at cohort enrollment was 63.6 (7.7) years, 4031 (56.3%) were male, and 3131 (43.7%) were female. The 10-year cumulative IPLC incidence was 2.40% (95% CI, 2.31%-2.49%) among ever-smokers, which was 7 times higher than never-smokers (0.34%; 95% CI, 0.30%-0.37%). However, the 10-year cumulative SPLC incidence following IPLC was as high among never-smokers (2.84%; 95% CI, 1.50%-4.18%) as ever-smokers (2.72%; 95% CI, 2.24%-3.20%), which led to a substantially higher SIR for never-smokers (14.50; 95% CI, 8.73-22.65) vs ever-smokers (3.50; 95% CI, 2.95-4.12).

Conclusions and Relevance

The findings indicate that SPLC risk among lung cancer survivors who never smoked is as high as among those with IPLC who ever-smoked, highlighting the need to identify risk factors for SPLC among patients who never smoked and to develop a targeted surveillance strategy.

miR-423-3p activates FAK signaling pathway to drive EMT process and tumor growth in lung adenocarcinoma through targeting CYBRD1

BACKGROUND

Lung adenocarcinoma (LUAD) is a malignant tumor with a high fatality rate and poor overall survival, while molecular targets diagnosing and alleviating lung cancer remain inadequate.

METHODS

In this article, we highlighted the upregulation of microRNA-423-3p (miR-423-3p) in LUAD, especially in smokers aged over 40, and revealed that the high expression of miR-423-3p was significantly associated with smoker, age, and pathologic stage of LUAD patients.

RESULTS

Moreover, overexpressing miR-423-3p could facilitate LUAD cell proliferation, invasion, adhesion, and epithelial-mesenchymal transition (EMT) process, while depleted miR-423-3p caused repressive influence upon it. Mechanically, we identified that miR-423-3p could activate FAK signaling pathway through binding to the 3'-UTR of cytochrome B reductase 1 (CYBRD1). Furthermore, we demonstrated that CYBRD1 was lowly expressed in LUAD, and miR-423-3p overexpression could rescue the impairment of LUAD cell proliferation, invasion, adhesion, and EMT caused by CYBRD1 depletion. Noticeably, miR-423-3p depletion efficiently hindered LUAD tumor growth in vivo.

CONCLUSION

Collectively, our findings demonstrated that miR-423-3p/CYBRD1 axis could be regarded as a promising biomarker to alleviate the poor LUAD prognosis.

Comparative evaluation of serum cotinine levels in chronic periodontitis and chronic obstructive pulmonary disease

Context:

Periodontitis and chronic obstructive pulmonary disease (COPD) are chronic progressive inflammatory conditions. Smoking has been associated with both chronic periodontitis and COPD. Hence, the present study was designed to correlate serum levels of cotinine with the severity of periodontal disease with or without COPD.

Settings and Design:

A total of eighty patients, twenty healthy individuals, twenty patients with chronic generalized periodontitis without smoking and without COPD, twenty patients who are smokers with chronic periodontitis without COPD and twenty patients who are smokers with chronic periodontitis and COPD in the age range of 43–65 years were selected for the study.

Subjects and Methods:

Serum cotinine level assessment, smoking history, and periodontal examination were done in all the patients and the data obtained were statistically analyzed.

Results:

The mean serum cotinine level was highest in smokers with chronic periodontitis and COPD (93.642 ± 14.727) and it differed significantly between the four groups (P < 0.001). There is a significant positive correlation between the number of cigarettes and serum cotinine levels in both groups involving smoking. There was no significant correlation between serum cotinine level and clinical attachment loss in chronic periodontitis smokers with or without COPD.

Conclusions:

The result of this study indicates that increased smoking with COPD causes a higher chance of progression of periodontal destruction but it is not statistically significant. Furthermore, this study indicates that the assessment of serum cotinine levels is a reliable method to evaluate smoking exposure.

Influence of single nucleotide polymorphisms among cigarette smoking and non-smoking patients with coronary artery disease, urinary bladder cancer and lung cancer

Introduction

Cigarette smoke is suggested to be a risk factor for coronary artery disease (CAD), urinary bladder cancer (UBCa) or lung cancer (LCa). However, not all heavy smokers develop these diseases and elevated cancer risk among first-degree relatives suggests an important role of genetic factor.

Methods

Three hundred and ten healthy blood donors (controls), 98 CAD, 74 UBCa and 38 LCa patients were included in this pilot study. The influence of 92 single nucleotide polymorphisms (SNPs) and impact of cigarette smoking were analysed.

Results

Out of 92 SNPs tested, differences in distribution of 14 SNPs were detected between controls and patient groups. Only CTLA4 rs3087243 showed difference in both CAD and UBCa patient group compared to control group. Stratified by smoking status, the impact of smoking was associated to frequencies of 8, 3 and 4 SNPs in CAD, UBCa, LCa patients, respectively. None of these 92 SNPs showed a statistically significant difference to more than one type of disease among smoking patients. In non-smoking patients, 7, 3 and 6 SNPs were associated to CAD, UBCa, LCa, respectively. Out of these 92 SNPs, CTLA4 rs3087243 was associated to both non-smoking CAD and UBCa. The XRCC1 rs25487 was associated to both non-smoking UBCa and LCa.

Conclusion

SNPs might be important risk factors for CAD, UBCa and LCa. Distribution of the SNPs was specific for each patient group, not a random event. Impact of cigarette smoking on the disease was associated to the specific SNP sequences. Thus, smoking individuals with SNPs associated to risk of these serious diseases is an important target group for smoking cessation programs.

Environmental and occupational determinants of lung cancer

Lung cancer has become a global problem, from a rare disease to an emerging public health issue. The current data of GLOBOCAN 2018, indicates that this disease has recorded highest mortality among all types of cancer. The etiological factors of lung cancer have become more multiplex because of increasing industrialization and environmental pollution around the world, especially in India. There is a rise in incidence of lung cancer among non-smokers and this can be attributed to environmental and occupational exposure to various kinds of hazardous substances. Target mutations are high in Lung cancer among non-smokers when compared to smokers. Some developed countries have guidelines and policies for prevention and control of risk factors focusing on these issues. Intervention aiming for primary prevention can be an important and cost-effective tool in developing countries to deal with increasing incidence of lung cancer. There is a need to define high risk group among non-smokers after taking into account environmental and occupational determinants as important risk factors. Research on etiology of lung cancer and prevention provides evidence to work on global incidence and prevalence of lung cancer, and for designing cost effective lung cancer prevention strategies. Research in the area of lung cancer prevention should be considered to recognize the areas where action is required to prevent environment and occupation related lung cancer. The government and occupational health and safety organizations have taken many steps in the last few years that can help to protect workers from these exposures. But the dangers are still there, so there is a need to do more to limit these exposures around workplace. This whole situation guides us to advocate population-based intervention along with policy implementation.

Concomitant TP53 mutations with response to crizotinib treatment in patients with ALK-rearranged non-small-cell lung cancer

Background

TP53 mutations are the most prevalent mutations detected in non‐small‐cell lung cancer (NSCLC) and have been revealed as a negative prognostic biomarker of outcome. The impact of concomitant TP53 mutations in ALK‐rearranged NSCLC remains uncertain.

Methods

Tumor samples from 64 ALK‐rearranged NSCLC patients receiving crizotinib treatment were subjected to next‐generation sequencing (NGS) to identify TP53 mutational status. The clinicopathologic features of the TP53 mutations and its impact on the effect of crizotinib treatment were analyzed.

Results

Among the 64 ALK‐rearranged patients, 15 (23.4%) patients showed a TP53 mutation. Of these, six cases had disruptive mutations and nine with nondisruptive mutations. The objective response rate (ORR) and disease control rate (DCR) for TP53 mutated patients were both significantly lower compared with those for TP53 wild‐type patients (p = 0.003 and 0.023, respectively). A significantly shorter progression‐free survival (PFS) was found in TP53 mutated patients compared with TP53 wild‐type patients (p = 0.045). Nondisruptive TP53 mutations were associated with a shorter PFS in comparison with disruptive TP53 mutations in ALK‐rearranged patients (p = 0.069). When nondisruptive TP53 mutated patients were in comparison with TP53 wild‐type patients, nondisruptive TP53 mutations were associated with a significant reduced PFS (p = 0.003).

Conclusions

TP53 mutations, especially nondisruptive mutations, negatively affected the response to crizotinib and correlated with shorter PFS in ALK‐rearranged NSCLC patients.

Meta-Analysis and Systematic Review in Environmental Tobacco Smoke Risk of Female Lung Cancer by Research Type

More than 50% of women worldwide are exposed to Environmental Tobacco Smoke (ETS). The impact of ETS on lung cancer remains unclear. Cohort studies since the late 1990s have provided new evidence of female lung cancer risk due to ETS. The objective of this meta-analysis and systematic review was to analyze the association of ETS with female lung cancer risk from 1997 to 2017, organised based on research design. According to our applied inclusion and exclusion criteria, 41 published studies were included. The relative risk (RR) from the cohort studies or odds ratio (OR) from case-control studies were extracted to calculate the pooled risks based on the type of study. The summary risks of ETS were further explored with the modulators of ETS exposure sources and doses. The pooled risks of lung cancer in non-smoking women exposed to ETS were 1.35 (95% CI: 1.17⁻1.56), 1.17 (95% CI: 0.94⁻1.44), and 1.33 (95% CI: 1.17⁻1.51) for case-control studies, cohort studies, and both types of studies, respectively. The summary RR estimate of the cohort studies was not statistically significant, but the RR increased with increasing doses of ETS exposure (p trend < 0.05). Based on the results of this study, ETS might be an important risk factor of female lung cancer in non-smokers.

CYP1A1 *2B and *4 Polymorphisms are associated with Lung Cancer Susceptibility in Mexican Patients

Background

CYP1A1 is a gene involved in the high aryl hydrocarbon hydroxylase -inducible phenotype, which is a genetically-determined variation among individuals that has been associated with lung cancer risk. More specifically, CYP1A1*2B and *4 polymorphisms have been associated with high susceptibility to lung cancer among cigarette smokers. Materials and methods: DNA was obtained from blood samples and we studied by PCR-RFLP the distribution of CYP1A1*2B (n=248) and *4 (n=222) polymorphisms in healthy controls and 222 lung cancer patients from a Mexican population.

Results

Comparisons between groups showed an increased risk for lung cancer patients of *2B/*2B (18%; OR 7.6; 95% CI 3.0–19.2) and *4/*4 genotypes (15%; OR 11.45; 95% CI 2.19–59.85) compared to the control group (1% for *2B/*2B and 4.4% for *4/*4). A significant association between lung cancer and homozygous *2B/*2B passive smokers and *4/*4 ever (cigarettes) and passive smokers was also observed (p<0.05). Multivariate analysis revealed an increased risk for the *2B/2B genotype (OR 6.83), as well as for *4/*4 (OR 28.8).

Conclusion

The results of the study indicate a significant association between *2B/*2B and *4/*4 genotypes and the risk of developing lung cancer among Mexicans.

Passive smoking and influenza-like illness in housewives: A perspective of gene susceptibility

Relation between influenza-like illness (ILI) and passive smoking remains a debate of subject. We aimed to determine an association of passive smoking with ILI risk of housewives in North China, and the modification effects of gene polymorphisms related to the metabolisms of smoking pollutants. We included 379 housewives for a cross-sectional study in Shanxi Province, China, including 118 with ILI frequency of "≥1 times per year" as the case group and 261 with ILI frequency of "<1 time per year" in the past 10 years as the control group. We collected their information on frequencies of passive smoking and ILI by questionnaires, as well as their single nucleotide polymorphisms (SNPs) of genes related to Phase I and Phase II metabolisms of smoking pollutants. Our results revealed a significant Spearman correlation between frequencies of ILI and passive smoking (r = 0.406, p < 0.001). Frequency of passive smoking was associated with an increased risk of ILI with adjusted OR [6.75 (95% confidence interval: 3.98-11.4)]. Dose-response association between the passive smoking and ILI risk was observed with or without adjusting for confounders. Mutant types of rs1041983 (N-acetyltransferase 2 gene, NAT2) had a synergetic effect with passive smoking on ILI frequency, while mutant types of rs1695 (glutathione S-transferase P1 gene, GSTP1) had an antagonistic effect. Overall, our study results supported the hypothesis that passive smoking was positively associated with ILI frequency in housewives and this effect was modified by gene polymorphisms of Phase II metabolism genes (NAT2 and GSTP1).

Role of Autophagy and Apoptosis in Non-Small-Cell Lung Cancer

Non-small-cell lung cancer (NSCLC) constitutes 85% of all lung cancers, and is the leading cause of cancer-related death worldwide. The poor prognosis and resistance to both radiation and chemotherapy warrant further investigation into the molecular mechanisms of NSCLC and the development of new, more efficacious therapeutics. The processes of autophagy and apoptosis, which induce degradation of proteins and organelles or cell death upon cellular stress, are crucial in the pathophysiology of NSCLC. The close interplay between autophagy and apoptosis through shared signaling pathways complicates our understanding of how NSCLC pathophysiology is regulated. The apoptotic effect of autophagy is controversial as both inhibitory and stimulatory effects have been reported in NSCLC. In addition, crosstalk of proteins regulating both autophagy and apoptosis exists. Here, we review the recent advances of the relationship between autophagy and apoptosis in NSCLC, aiming to provide few insights into the discovery of novel pathogenic factors and the development of new cancer therapeutics.

Female Cigarette and Alcohol Consumption as a Short-Term Mating Strategy

In developed countries, the traditional gender gap in youth smoking and drinking is closing. As tobacco and alcohol are more harmful to women than to men, this is an alarming trend. As men are generally more short-term oriented in their sexuality than women, and given that cigarette and alcohol use are still considered masculine behaviors, we explored if female smoking and drinking can function as a short-term mating strategy. By means of a between-subjects experiment ( N = 218), men’s perceptions of female smoking and drinking were studied. The experiment showed that young men perceive women who use cigarettes and alcohol as being more sexually unrestricted. Furthermore, tobacco and (especially) alcohol use brought some short-term attractiveness benefits to women. In short-term mating contexts, drinking enhanced women’s attractiveness, whereas occasional smoking was found equally desirable as not smoking. However, in long-term mating contexts, frequent drinking and all smoking behavior harmed women’s desirability. A follow-up study ( N = 202) confirmed men’s perceptions, showing that female users of tobacco and alcohol are indeed more short-term oriented in their sexuality. Overall, results indicate that female smoking and drinking can operate as a short-term mating strategy.

Association of polycyclic aromatic hydrocarbons in housewives' hair with hypertension

The relationship between polycyclic aromatic hydrocarbons (PAHs) and hypertension remains a subject of debate. The aims of this study were to determine an association of concentrations of PAHs in housewives' hair with hypertension risk and the modification effect of single nucleotide polymorphisms (SNPs) related to Phase I metabolism of PAHs. We recruited 405 women for a cross-sectional study in Shanxi Province, China, including 170 with hypertension (the case group) and 235 without hypertension (the control group). We analyzed 26 individual PAHs in hair samples and the SNPs of the genes including cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1), CYP1A2, CYP1B1 and CYP2E1. Our results showed that seven PAHs in hair samples were measured with detection rate >70%. Only acenaphthylene was found to be associated with an increased risk of hypertension with adjustment for the potential confounders following Bonferroni correction, whereas others not. No SNPs of the concerned genes were found to be associated with the risk of hypertension. A multiple interaction effect of PAHs in housewives' hair and SNPs on hypertension risk was not observed. It was concluded that PAHs tended to contribute to the formation of hypertension.

Polycyclic aromatic hydrocarbons: from metabolism to lung cancer

Excessive exposure to polycyclic aromatic hydrocarbons (PAHs) often results in lung cancer, a disease with the highest cancer mortality in the United States. After entry into the lung, PAHs induce phase I metabolic enzymes such as cytochrome P450 (CYP) monooxygenases, i.e. CYP1A1/2 and 1B1, and phase II enzymes such as glutathione S-transferases, UDP glucuronyl transferases, NADPH quinone oxidoreductases (NQOs), aldo-keto reductases (AKRs), and epoxide hydrolases (EHs), via the aryl hydrocarbon receptor (AhR)-dependent and independent pathways. Humans can also be exposed to PAHs through diet, via consumption of charcoal broiled foods. Metabolism of PAHs through the CYP1A1/1B1/EH pathway, CYP peroxidase pathway, and AKR pathway leads to the formation of the active carcinogens diol-epoxides, radical cations, and o-quinones. These reactive metabolites produce DNA adducts, resulting in DNA mutations, alteration of gene expression profiles, and tumorigenesis. Mutations in xenobiotic metabolic enzymes, as well as polymorphisms of tumor suppressor genes (e.g. p53) and/or genes involved in gene expression (e.g. X-ray repair cross-complementing proteins), are associated with lung cancer susceptibility in human populations from different ethnicities, gender, and age groups. Although various metabolic activation/inactivation pathways, AhR signaling, and genetic susceptibilities contribute to lung cancer, the precise points at which PAHs induce tumor initiation remain unknown. The goal of this review is to provide a current state-of-the-science of the mechanisms of human lung carcinogenesis mediated by PAHs, the experimental approaches used to study this complex class of compounds, and future directions for research of these compounds.

Environmental tobacco smoke exposure and lung cancer: A systematic review

AIM: To review evidence relating passive smoking to lung cancer risk in never smokers, considering various major sources of bias.

METHODS: Epidemiological prospective or case-control studies were identified which provide estimates of relative risk (RR) and 95%CI for never smokers for one or more of seven different indices of exposure to environmental tobacco smoke (ETS): The spouse; household; workplace; childhood; travel; social and other; and total. A wide range of study details were entered into a database, and the RRs for each study, including descriptions of the comparisons made, were entered into a linked database. RRs were derived where necessary. Results were entered, where available, for all lung cancer, and for squamous cell cancer and adenocarcinoma. “Most adjusted” results were entered based on results available, adjusted for the greatest number of potential confounding variables. “Least adjusted” results were also entered, with a preference for results adjusted at least for age for prospective studies. A pre-planned series of fixed-effects and random-effects meta-analyses were conducted. Overall analyses and analyses by continent were run for each exposure index, with results for spousal smoking given by sex, and results for childhood exposure given by source of ETS exposure. For spousal exposure, more extensive analyses provide results by various aspects of study design and definition of the RR. For smoking by the husband (or nearest equivalent), additional analyses were carried out both for overall risk, and for risk per 10 cigarettes per day smoked by the husband. These adjusted for uncontrolled confounding by four factors (fruit, vegetable and dietary fat consumption, and education), and corrected for misclassification of smoking status of the wife. For the confounding adjustment, estimates for never smoking women were derived from publications on the relationship of the four factors to both lung cancer risk and at home ETS exposure, and on the correlations between the factors. The bias due to misclassification was calculated on the basis that the proportion of ever smokers denying smoking is 10% in Asian studies and 2.5% elsewhere, and that those who deny smoking have the same risk as those who admit it. This approach, justified in previous work, balances higher true denial rates and lower risk in deniers compared to non-deniers.

RESULTS: One hundred and two studies were identified for inclusion, published in 1981 onwards, 45 in Asia, 31 in North America, 21 in Europe, and five elsewhere. Eighty-five were of case-control design and 17 were prospective. Significant (P < 0.05) associations were noted, with random-effects of (RR = 1.22, 95%CI: 1.14-1.31, n = 93) for smoking by the husband (RR = 1.14, 95%CI: 1.01-1.29, n = 45) for smoking by the wife (RR = 1.22, 95%CI: 1.15-1.30, n = 47) for workplace exposure (RR = 1.15, 95%CI: 1.02-1.29, n = 41) for childhood exposure, and (RR = 1.31, 95%CI: 1.19-1.45, n = 48) for total exposure. No significant association was seen for ETS exposure in travel (RR = 1.34, 95%CI: 0.94-1.93, n = 8) or in social situations (RR = 1.01, 95%CI: 0.82-1.24, n = 15). A significant negative association (RR = 0.78, 95%CI: 0.64-0.94, n = 8) was seen for ETS exposure in childhood, specifically from the parents. Significant associations were also seen for spousal smoking for both squamous cell carcinoma (RR = 1.44, 95%CI: 1.15-1.80, n = 24) and adenocarcinoma (RR = 1.33, 95%CI: 1.17-1.51, n = 30). Results generally showed marked heterogeneity between studies. For smoking by either the husband or wife, where 119 RR estimates gave an overall estimate of (RR = 1.21, 95%CI: 1.14-1.29), the heterogeneity was highly significant (P < 0.001), with evidence that the largest RRs were seen in studies published in 1981-89, in small studies (1-49 cases), and for estimates unadjusted by age. For smoking by the husband, the additional analyses showed that adjustment for the four factors reduced the overall (RR = 1.22, 95%CI: 1.14-1.31) based on 93 estimates to (RR = 1.14, 95%CI: 1.06-1.22), implying bias due to uncontrolled confounding of 7%. Further correction for misclassification reduced the estimate to a marginally non-significant (RR = 1.08, 95%CI: 0.999-1.16). In the fully adjusted and corrected analyses, there was evidence of an increase in Asia (RR = 1.18, 95%CI: 1.07-1.30, n = 44), but not in other regions (RR = 0.96, 95%CI: 0.86-1.07, n = 49). Studies published in the 1980’s, studies providing dose-response data, and studies only providing results unadjusted for age showed elevated RRs, but later published studies, studies not providing dose-response data, and studies adjusting for age did not. The pattern of results for RRs per 10 cigs/d was similar, with no significant association in the adjusted and corrected results (RR = 1.03, 95%CI: 0.994-1.07).

CONCLUSION: Most, if not all, of the ETS/lung cancer association can be explained by confounding adjustment and misclassification correction. Any causal relationship is not convincingly demonstrated.

Gene mutation discovery research of non-smoking lung cancer patients due to indoor radon exposure

Although the incidence and mortality for most cancers such as lung and colon are decreasing in several countries, they are increasing in several developed countries because of an unhealthy western lifestyles including smoking, physical inactivity and consumption of calorie-dense food. The incidences for lung and colon cancers in a few of these countries have already exceeded those in the United States and other western countries. Among them, lung cancer is the main cause of cancer death in worldwide. The cumulative survival rate at five years differs between 13 and 21 % in several countries. Although the most important risk factors are smoking for lung cancer, however, the increased incidence of lung cancer in never smokers(LCINS) is necessary to improve knowledge concerning other risk factors. Environmental factors and genetic susceptibility are also thought to contribute to lung cancer risk. Patients with lung adenocarcinoma who have never smoking frequently contain mutation within tyrosine kinase domain of the epidermal growth factor receptor(EGFR) gene. Also, K-ras mutations are more common in individuals with a history of smoking use and are related with resistance to EFGR-tyrosine kinase inhibitors. Recently, radon(Rn), natural and noble gas, has been recognized as second common reason of lung cancer. In this review, we aim to know whether residential radon is associated with an increased risk for developing lung cancer and regulated by several genetic polymorphisms.

Smoking, passive smoking and lung cancer cell types among women in Morocco: analysis of epidemiological profiling of 101 cases

Background

Recently women’s lung cancer mortality rates have dramatically increased in developed countries, contrasting with a levelling off or decrease among men. Descriptive epidemiological data on primary lung cancer in women is scarce in Morocco. The aim of this study, conducted in the National Institute of Oncology in Rabat, was to describe the epidemiological profiling especially for the smoking status, to determine the most frequent type of lung cancer, and to analyse the survival of Moroccan women with lung cancer diagnosis.

Results

We found 101 women among 1680 (male and female) cases of lung cancer. The never-smokers were estimated to 75 %. The proportion of adenocarcinoma among never and passive smokers was higher than that of squamous cell carcinoma (SCC) (69.4 versus 30.6 %), while among women who were smokers, the most frequent histological type was SCC (63.6 %). The Cox regression analysis showed that smoking and passive smoking were not significantly associated with survival [HR: 0.62 (95 % CI 0.31, 1.30); p = 0.19] [HR: 0.56 (95 % CI 0.29, 1.08); p = 0.08] respectively. Adenocarcinoma was significantly associated with shorter survival [HR: 1.73 (95 % CI 1.05, 2.85); p = 0.03].

Conclusions

The majority Moroccan women affected by lung cancer have never smoked (75 %). Environmental exposures, genetic predisposition, hormonal factors, and viral infection may all play a role in lung cancer in this category. The relation between histological type and tobacco found in our series concurred with those reported in the literature—adenocarcinoma appears to be the most frequent cell type affecting never and passive smokers. Adenocarcinoma is significantly associated with poorer survival.

The relationship between smoking and quality of life in advanced lung cancer patients: a prospective longitudinal study

PURPOSE

Smoking is a major cause of lung cancer, and continued smoking may compromise treatment efficacy and quality of life (health-related quality of life (HRQoL)) in patients with advanced lung cancer. Our aims were to determine (i) preference for treatments which promote quality over length of life depending on smoking status, (ii) the relationship between HRQoL and smoking status at diagnosis (T1), after controlling for demographic and clinical variables, and (iii) changes in HRQoL 6 months after diagnosis (T2) depending on smoking status.

METHODS

Two hundred ninety-six patients with advanced lung cancer were given questionnaires to assess HRQoL (EORTC QLQ-C30), time-trade-off for life quality versus quantity (QQQ) and smoking history (current, former or never smoker) at diagnosis (T1) and 6 months later (T2). Medical data were extracted from case records.

RESULTS

Questionnaires were returned by 202 (68.2 %) patients at T1 and 114 (53.3 %) at T2. Patients favoured treatments that would enhance quality of life over increased longevity. Those who continued smoking after diagnosis reported worse HRQoL than former smokers or those who never smoked. Smoking status was a significant independent predictor of coughing in T1 (worse in smokers) and cognitive functioning in T2 (better in never smokers).

CONCLUSIONS

Smoking by patients with advanced lung cancer is associated with worse symptoms on diagnosis and poorer HRQoL for those who continue smoking. The results have implications to help staff explain the consequences of smoking to patients.

No impact of passive smoke on the somatic profile of lung cancers in never-smokers

EGFR and HER2 mutations and ALK rearrangement are known to be related to lung cancer in never-smokers, while KRAS, BRAF and PIK3CA mutations are typically observed among smokers. There is still debate surrounding whether never-smokers exposed to passive smoke exhibit a “smoker-like” somatic profile compared with unexposed never-smokers.

Passive smoke exposure was assessed in the French BioCAST/IFCT-1002 never-smoker lung cancer cohort and routine molecular profiles analyses were compiled.

Of the 384 patients recruited into BioCAST, 319 were tested for at least one biomarker and provided data relating to passive smoking. Overall, 219 (66%) reported having been exposed to passive smoking. No significant difference was observed between mutation frequency and passive smoke exposure (EGFR mutation: 46% in never exposed versus 41% in ever exposed; KRAS: 7% versus 7%; ALK: 13% versus 11%; HER2: 4% versus 5%; BRAF: 6% versus 5%; PIK3CA: 4% versus 2%). We observed a nonsignificant trend for a negative association between EGFR mutation and cumulative duration of passive smoke exposure. No association was found for other biomarkers.

There is no clear association between passive smoke exposure and somatic profile in lifelong, never-smoker lung cancer.

Molecular Links between Alcohol and Tobacco Induced DNA Damage, Gene Polymorphisms and Patho-physiological Consequences: A Systematic Review of Hepatic Carcinogenesis

Chronic alcohol and tobacco abuse plays a crucial role in the development of different liver associated disorders. Intake promotes the generation of reactive oxygen species within hepatic cells exposing their DNA to continuous oxidative stress which finally leads to DNA damage. However in response to such damage an entangled protective repair machinery comprising different repair proteins like ATM, ATR, H2AX, MRN complex becomes activated. Under abnormal conditions the excessive reactive oxygen species generation results in genetic predisposition of various genes (as ADH, ALDH, CYP2E1, GSTT1, GSTP1 and GSTM1) involved in xenobiotic metabolic pathways, associated with susceptibility to different liver related diseases such as fibrosis, cirrhosis and hepatocellular carcinoma. There is increasing evidence that the inflammatory process is inherently associated with many different cancer types, including hepatocellular carcinomas. The generated reactive oxygen species can also activate or repress epigenetic elements such as chromatin remodeling, non-coding RNAs (micro-RNAs), DNA (de) methylation and histone modification that affect gene expression, hence leading to various disorders. The present review provides comprehensive knowledge of different molecular mechanisms involved in gene polymorphism and their possible association with alcohol and tobacco consumption. The article also showcases the necessity of identifying novel diagnostic biomarkers for early cancer risk assessment among alcohol and tobacco users.

Microfluidic immunoassay for rapid detection of cotinine in saliva

A microfluidic immunoassay is successfully developed for rapid analysis of cotinine saliva samples, which is a metabolite of nicotine and is widely used as a biomarker to evaluate the smoking status and exposure to tobacco smoke. The core microfluidic chip is fabricated by polydimethylsiloxane (PDMS) with standard soft lithography. Each chip is capable of eight parallel analyses of cotinine samples. The analyses can be completed within 40 min with 12 μl sample consumption. The linear detection range is 1 ~ 250 ng/ml and the minimum detectable concentration is 1 ng/ml respectively. The correlation coefficient of the calibration curve established from standard samples is 0.9989. The immunoassay was also validated by real saliva samples, and the results showed good reproducibility and accuracy. All the results were confirmed with traditional ELISA measurements. The result from microfluidic chip device and ELISA kits showed good correspondence, and the correlation coefficients are higher than 0.99. Compared with traditional technique, this microfluidic immunoassay is more economic, rapid, simple and sensitive, perfect for on-site cotinine measurements as well as for the evaluation of the exposure to tobacco smoking. Moreover, this immunoassay has potential to be applied in the analysis of other biomarkers in human saliva samples.

Association of CYP1A1 and CYP2D6 gene polymorphisms with head and neck cancer in Tunisian patients

The purpose of this study was to investigate the relationship between head and neck cancer (HNC) and environmental agents and polymorphisms in CYP1A1, CYP2D6, NAT1 and NAT2 metabolic enzymes genes. To the best of our knowledge, this is the first report on polymorphisms in CYP1A1 6310C>T, CYP2D6 Arg365His, NAT1 52936A>T and NAT2 Arg268Lys (NAT2*12A) genes and susceptibility to HNC in Tunisian population. We study the prevalence of these polymorphisms in 169 patients with HNC and 261 control subjects using polymerase chain reaction based methods in a Tunisian population. We detected an association between HNC and CYP1A1 6310C>T (TT) and CYP2D6 Arg365His (His/His) variant carriers (OR 1.75, P = 0.008 and OR 1.66, P = 0.016, respectively). No association was found between the polymorphisms genotypes of NAT1 52936T>A and NAT2 Arg268Lys and risk of HNC. An association between HNC and CYP1A1 (TT) genotype was found among patients with smoking (P = 0.011) and drinking habit (P = 0.009). The combinations of NAT1 (AT or AA) and NAT2 (AA) at-risk genotypes increased HNC risk (OR 4.23, P = 0.005 and OR 3.60, P = 0.048, respectively). However, the combinations of CYP1A1 (AA) and CYP2D6 (CC) genotypes decreased risk of HNC (OR 0.20; P = 0.006). Genetic polymorphisms in CYP1A1 and CYP2D6 may significantly associate with HNC in the Tunisian population. The results of this study suggest a possible gene-environment interaction for certain carcinogen metabolizing enzymes, but larger studies that fully evaluate the interaction are needed.

A Tutorial on Interaction

In this tutorial, we provide a broad introduction to the topic of interaction between the effects of exposures. We discuss interaction on both additive and multiplicative scales using risks, and we discuss their relation to statistical models (e.g. linear, log-linear, and logistic models). We discuss and evaluate arguments that have been made for using additive or multiplicative scales to assess interaction. We further discuss approaches to presenting interaction analyses, different mechanistic forms of interaction, when interaction is robust to unmeasured confounding, interaction for continuous outcomes, qualitative or “crossover” interactions, methods for attributing effects to interactions, case-only estimators of interaction, and power and sample size calculations for additive and multiplicative interaction.

Polymorphisms in the human cytochrome P450 and arylamine N-acetyltransferase: susceptibility to head and neck cancers

The occurrence of head and neck cancer (HNC) is associated with smoking and alcohol drinking. Tobacco smoking exposes smokers to a series of carcinogenic chemicals. Cytochrome P450 enzymes (CYP450s), such as CYP1A1, CYP1B1, and CYP2D6, usually metabolize carcinogens to their inactive derivatives, but they occasionally convert the chemicals to more potent carcinogens. In addition, via CYP450 (CYP2E1) oxidase, alcohol is metabolized to acetaldehyde, a highly toxic compound, which plays an important role in carcinogenesis. Furthermore, two N-acetyltransferase isozymes (NATs), NAT1 and NAT2, are polymorphic and catalyze both N-acetylation and O-acetylation of aromatic and heterocyclic amine carcinogens. Genetic polymorphisms are associated with a number of enzymes involved in the metabolism of carcinogens important in the induction of HNC. It has been suggested that such polymorphisms may be linked to cancer susceptibility. In this paper, we select four cytochrome P450 enzymes (CYP1A1, CYP1BA1, CYP2D6, and CYP2E1), and two N-acetyltransferase isozymes (NAT1 and NAT2) in order to summarize and analyze findings from the literature related to HNC risk by focusing on (i) the interaction between these genes and the environment, (ii) the impact of genetic defect on protein activity and/or expression, and (iii) the eventual involvement of race in such associations.

Measuring molecular biomarkers in epidemiologic studies: laboratory techniques and biospecimen considerations

The future of personalized medicine depends on the ability to efficiently and rapidly elucidate a reliable set of disease-specific molecular biomarkers. High-throughput molecular biomarker analysis methods have been developed to identify disease risk, diagnostic, prognostic, and therapeutic targets in human clinical samples. Currently, high throughput screening allows us to analyze thousands of markers from one sample or one marker from thousands of samples and will eventually allow us to analyze thousands of markers from thousands of samples. Unfortunately, the inherent nature of current high throughput methodologies, clinical specimens, and cost of analysis is often prohibitive for extensive high throughput biomarker analysis. This review summarizes the current state of high throughput biomarker screening of clinical specimens applicable to genetic epidemiology and longitudinal population-based studies with a focus on considerations related to biospecimens, laboratory techniques, and sample pooling.

Lung cancer in never smokers

Lung cancer in never smokers (LCINS) is the seventh leading cause of death among solid tumors. The main risk factor for lung cancer is smoking; however, approximately 15% of lung cancer patients have never smoked. LCINS is more frequent in women, irrespective of geographical location, nevertheless, the highest incidence has been found in South-East Asia. The histological incidence of adenocarcinoma is higher in the group of never smokers than squamous cell carcinoma. There is a familial clustering of lung cancer that is more pronounced in never smokers, where the family history was associated with an increased risk. Genome-wide association studies identified certain chromosomal aberrations in LCINS. Furthermore, the oncogenic mutation pattern is distinct in nonsmoking patients: activating mutations of EGFR or anaplastic lymphoma kinase are more frequent. The etiology of LCINS includes several environmental factors as well, such as environmental tobacco smoke, viral and hormonal factors, a variety of pulmonary diseases and certain occupational exposures. It is now established that EGFR-tyrosine kinase inhibitor treatment (erlotinib and geftinib) in lung cancer is more effective in LCINS, owing to the higher incidence of EGFR mutation in nonsmokers. Despite the growing body of information on LCINS in recent years there is a need to further investigate the pathogenesis of this particular lung cancer. Future studies on LCINS should try to tackle the issues of prevention, early diagnosis and the exploration of novel therapeutic targets to combat lung cancer disease.

Epidemiology of lung cancer: smoking, secondhand smoke, and genetics

The link between smoking and development of lung cancer has been demonstrated, not only for smokers but also for those exposed to secondhand smoke. Despite the obvious carcinogenic effects of tobacco smoking, not all smokers develop lung cancer, and conversely some nonsmokers can develop lung cancer in the absence of other environmental risk factors. A multitude of genetic factors are beginning to be explored that interact with environmental exposure to alter the risk of developing this deadly disease. By more fully appreciating the complex interrelationship between genetics and other risks the development of lung cancer can be more completely understood.

Stochastic counterfactuals and stochastic sufficient causes

Most work in causal inference concerns deterministic counterfactuals; the literature on stochastic counterfactuals is small. In the stochastic counterfactual setting, the outcome for each individual under each possible set of exposures follows a probability distribution so that for any given exposure combination, outcomes vary not only between individuals but also probabilistically for each particular individual. The deterministic sufficient cause framework supplements the deterministic counterfactual framework by allowing for the representation of counterfactual outcomes in terms of sufficient causes or causal mechanisms. In the deterministic sufficient cause framework it is possible to test for the joint presence of two causes in the same causal mechanism, referred to as a sufficient cause interaction. In this paper, these ideas are extended to the setting of stochastic counterfactuals and stochastic sufficient causes. Formal definitions are given for a stochastic sufficient cause framework. It is shown that the empirical conditions that suffice to conclude the presence of a sufficient cause interaction in the deterministic sufficient cause framework suffice also to conclude the presence of a sufficient cause interaction in the stochastic sufficient cause framework. Two examples from the genetics literature, in which there is evidence that sufficient cause interactions are present, are discussed in light of the results in this paper.

Sensitivity analysis for interactions under unmeasured confounding

We develop a sensitivity analysis technique to assess the sensitivity of interaction analyses to unmeasured confounding. We give bias formulas for sensitivity analysis for interaction under unmeasured confounding on both additive and multiplicative scales. We provide simplified formulas in the case in which either one of the two factors does not interact with the unmeasured confounder in its effects on the outcome. An interesting consequence of the results is that if the two exposures of interest are independent (e.g., gene-environment independence), even under unmeasured confounding, if the estimate of the interaction is nonzero, then either there is a true interaction between the two factors or there is an interaction between one of the factors and the unmeasured confounder; an interaction must be present in either scenario. We apply the results to two examples drawn from the literature.

Lung cancer in never smokers

Lung cancer in never smokers (LCINS) has lately been recognized as a unique disease based on rapidly gained knowledge from genomic changes to treatment responses. The focus of this article is on current knowledge and challenges with regard to LCINS expanded from recent reviews highlighting five areas: (1) distribution of LCINS by temporal trends, geographic regions, and populations; (2) three well-recognized environmental risk factors; (3) other plausible environmental risk factors; (4) prior chronic lung diseases and infectious diseases as risk factors; and (5) lifestyles as risk or protective factors. This article will also bring attention to recently published literature in two pioneering areas: (1) histological characteristics, clinical features with emerging new effective therapies, and social and psychological stigma; and (2) searching for susceptibility genes using integrated genomic approaches.

TP53 mutations in nonsmall cell lung cancer

The tumor suppressor gene TP53 is frequently mutated in human cancers. Abnormality of the TP53 gene is one of the most significant events in lung cancers and plays an important role in the tumorigenesis of lung epithelial cells. Human lung cancers are classified into two major types, small cell lung cancer (SCLC) and nonsmall cell lung cancer (NSCLC). The latter accounts for approximately 80% of all primary lung cancers, and the incidence of NSCLC is increasing yearly. Most clinical studies suggest that NSCLC with TP53 alterations carries a worse prognosis and may be relatively more resistant to chemotherapy and radiation. A deep understanding of the role of TP53 in lung carcinogenesis may lead to a more reasonably targeted clinical approach, which should be exploited to enhance the survival rates of patients with lung cancer. This paper will focus on the role of TP53 in the molecular pathogenesis, epidemiology, and therapeutic strategies of TP53 mutation in NSCLC.

Environmental tobacco smoke in relation to bladder cancer risk--the Shanghai bladder cancer study [corrected]

BACKGROUND

Environmental tobacco smoke (ETS) contains tobacco carcinogens. Hepatic cytochrome P450 (CYP) 1A2 and N-acetyltransferase (NAT2) are important isoenzymes in activation and detoxification, respectively, of tobacco carcinogens. Data on ETS and bladder cancer risk are sparse.

METHODS

We examined the effects of ETS alone and combined with NAT2/CYP1A2 on bladder cancer risk among lifelong-nonsmokers in a case-control study involving 195 patients and 261 controls in Shanghai, China. A comprehensive history of ETS exposure was determined through in-person interviews while CYP1A2 and NAT2 phenotypes by a caffeine-based urinary assay.

RESULTS

ETS exposure was related to an overall statistically nonsignificant 38% increased bladder cancer risk. The risk increased with increasing number of cigarettes smoked by household members or number of hours per day at workplace where coworkers smoked. Compared with no ETS exposure, subjects living with smoking parents during childhood had an OR of 2.43 (95% CI = 0.99-5.96) for bladder cancer. When all ETS sources were combined, the risk increased with increasing total ETS score (P(trend) = 0.03). The OR for high versus nil ETS exposure was 3.00 (95% CI = 1.24-7.26). The increased risk with ETS was mainly seen among individuals possessing a CYP1A2 high efficiency and/or a NAT2 slow acetylation phenotype (P(trend) = 0.04).

CONCLUSIONS

ETS was associated with an increased bladder cancer risk for lifelong-nonsmokers. The association was stronger for people possessing the at-risk phenotypes of CYP1A2 and/or NAT2.

IMPACT

Reducing exposure to ETS for children and genetically more susceptible individuals could be more effective for bladder cancer prevention.

Case-only gene-environment interaction studies: when does association imply mechanistic interaction?

Case-only studies are often used to identify interactions between a genetic factor and an environmental factor under the assumption both factors are independent in the population. However, interpreting a statistical association between the genetic and the environmental factors among the cases, as evidence of a mechanistic gene-environment interaction, is not always warranted. Using a mechanistic approach based on the sufficient cause framework, we show association amongst cases can arise between the genetic and environmental factors when there is in fact no mechanistic gene-environment interaction. However, when it can be assumed the genetic and environmental factors themselves can never prevent the outcome, we show a positive association amongst cases implies a mechanistic gene-environment interaction. Without this assumption that the effects of the two factors are never preventive, a multiplicative interaction greater than two is needed to conclude the presence of a mechanistic interaction. We furthermore show these tests for mechanistic interaction can be extended to scenarios in which the genetic and environmental factors are negatively associated in the population rather than independent.

Biomarkers of exposure to combustion by-products in a human population in Shanxi, China

Emissions of complex mixtures of polycyclic aromatic hydrocarbons (PAHs) and other compounds into the environment represent a potential threat to the health of humans. Information regarding the dose and duration of exposure is essential to determine the degree of risk and to identify sensitive receptors within a population. Although measurements of chemical concentrations in air may be used to estimate exposures, internal biomarkers provide more accurate information regarding the dose of exposure and retention of toxic chemicals. This study was conducted in a population in rural China exposed to PAHs from a variety of sources. The study population was located in an area known to have an elevated incidence of birth defects. Parents of children born with a neural tube defect (NTD) were recruited as case participants and parents of children born with no visible birth defect were recruited as controls. The study was designed to test the hypothesis that parents of children born with a NTD would exhibit a biomarker of exposure at higher levels than the parents of a child with no visible birth defect. A total of 35 mothers and 32 fathers were recruited as case participants, and 18 mothers and 19 fathers were recruited as control participants. Venous blood was collected from the study participants by hospital staff as soon as possible following the birth of the child. PAHs were isolated from the whole blood by solvent extraction and DNA was isolated from a separate aliquot of blood for (32)P-postlabeling to measure bulky adducts. Single Nucleotide Polymorphisms (SNPs) in phase II enzymes were also monitored in an attempt to identify sensitive receptors. Both total and carcinogenic PAH (cPAH) concentrations were elevated in the parents of case children. Both values were elevated significantly in mothers, whereas only cPAH concentrations were elevated significantly in fathers. Levels of DNA adducts were highly variable and displayed a reverse pattern to that of PAH levels in blood. None of the polymorphisms evaluated were correlated with PAH levels or DNA adducts. For mothers, whose total PAH concentration was above the median concentration, the age-adjusted odds ratio (OR) for having a child with a NTD was 8.7. Although this suggests that PAHs may be a contributing factor to the risk of NTDs, the lack of a correlation with DNA adducts would suggest a possible non-genotoxic mechanism. Alternatively, the PAHs may be a surrogate for a different exposure that is more directly related to the birth defects. The results have shown that blood levels of PAHs may be used to identify populations exposed to elevated concentrations of combustion by-products.

Lung cancer in never smokers: molecular profiles and therapeutic implications

The majority of lung cancers are caused by long term exposure to the several classes of carcinogens present in tobacco smoke. Although a significant fraction of lung cancers in never smokers may also be attributable to tobacco, many such cancers arise in the absence of detectable tobacco exposure, and may follow a very different cellular and molecular pathway of malignant transformation. Recent studies summarized here suggest that lung cancers arising in never smokers have a distinct natural history, profile of oncogenic mutations, and response to targeted therapy. The majority of molecular analyses of lung cancer have focused on genetic profiling of pathways responsible for metabolism of primary tobacco carcinogens. Limited research has been conducted evaluating familial aggregation and genetic linkage of lung cancer, particularly among never smokers in whom such associations might be expected to be strongest. Data emerging over the past several years show that lung cancers in never smokers are much more likely to carry activating mutations of the epidermal growth factor receptor (EGFR), a key oncogenic factor and direct therapeutic target of several newer anticancer drugs. EGFR mutant lung cancers may represent a distinct class of lung cancers, enriched in the never-smoking population, and less clearly linked to direct tobacco carcinogenesis. These insights followed initial testing and demonstration of efficacy of EGFR-targeted drugs. Focused analysis of molecular carcinogenesis in lung cancers in never smokers is needed, and may provide additional biologic insight with therapeutic implications for lung cancers in both ever smokers and never smokers.

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.

Tobacco, Genetic Susceptibility and Lung cancer

Exposure to tobacco smoke is an established risk factor for lung cancer, although a possible role for genetic susceptibility in the development of lung cancer has been inferred from familial clustering of the disease and segregation analysis. Findings of familial aggregation and statistical evidence for a major susceptibility gene have led to the search for high penetrant, rare, single genes and low penetrant, high frequency susceptibility genes for lung cancer. The relatively small number of linkage studies conducted to date, have identified potential lung cancer susceptibility loci on chromosomes 6q, 12p, and 19q. A variety of studies have examined single nucleotide polymorphisms of several low penetrant, high frequency genes encoding for enzymes involved in the metabolism of carcinogens and DNA damage repair, as likely candidate susceptibility genes. These studies have produced somewhat conflicting findings and, when significant, only modest associations have been reported. Relatively few studies have looked for potential gene-environment interactions, explored associations between two or more genetic polymorphisms or evaluated interactions between genetic polymorphisms and endogenous risk factors. Few large scale genome wide association studies conducted recently have provided evidence that common variation on chromosome 15q25.1, 5p15.33 and 6p21.33 influences lung cancer risk and cancer types with strong environmental risk factors. It is hoped that newer research strategies, selecting candidate genes within pathways and genotype at multiple markers within a gene, employing new technologies, may allow complete coverage of the variation within candidate genes in multiple pathways and to unravel the genetic susceptibility to lung cancer. This knowledge could, in turn, be used to identify persons at risk, to individualize treatments such as chemoprevention, to personalize harms of smoking and to motivate cessation.

Effect of gene-environment Interactions on mental development in African American, Dominican, and Caucasian mothers and newborns

The health impact of environmental toxins has gained increasing recognition over the years. Polycyclic aromatic hydrocarbons (PAHs) and environmental tobacco smoke (ETS) are known to affect nervous system development in children, but no studies have investigated how polymorphisms in PAH metabolic genes affect child cognitive development following PAH exposure during pregnancy. In two parallel prospective cohort studies of non-smoking African American and Dominican mothers and children in New York City and of Caucasian mothers and children in Krakow, Poland, we explored the effect of gene-PAH interaction on child mental development index (MDI). Genes known to play important roles in the metabolic activation or detoxification of PAHs were selected. Genetic variations in these genes could influence susceptibility to adverse effects of PAHs in polluted air. We explored the effects of interactions between prenatal PAH exposure and 21 polymorphisms or haplotypes in these genes on MDI at 12, 24, and 36 months among 547 newborns and 806 mothers from three different ethnic groups. Significant interaction effects between haplotypes and PAHs were observed in mothers and their newborns in all three ethnic groups after Bonferroni correction. The strongest and most consistent effect observed was between PAH and haplotype ACCGGC of the CYP1B1 gene.

Women and tobacco control policies: social-structural and psychosocial contributions to vulnerability to tobacco use and exposure

This article explores the psychosocial and social-structural vulnerability in relation to women's tobacco use, smoke exposure and responses to policy, and examines these issues in the context of women's lives and roles, describing forward looking strategies that could improve research and equity in outcomes for women. Various literatures on smoking among women and girls, and how women and sub-populations of women respond to tobacco control policies are reviewed. Specific sub-populations exhibiting more tobacco use and exposure are described, such as young pregnant and mothering women and low-income women. Emerging evidence also reveals links between smoking and experiences such as childhood sexual abuse, interpersonal violence, post-traumatic stress disorder, mental health issues and alcohol and drug dependence. Varied sub-populations of women respond in different ways to price and taxation, sales restrictions and location restrictions. However, tobacco control policies have, to date, been fashioned as broad instruments, not taking into account social context, trauma backgrounds, gendered roles such as mothering, unequal power relations affecting women in relationships and workplaces, and differences in access to resources and social support. When these issues are considered, the implications for tobacco policy development include: widening the policy purview, accounting for uneven and differential responses to policies, committing to an ethical framework, extending sex, gender and diversity based analyses, and improving research methods and approaches.

Lung cancer in never smokers: clinical epidemiology and environmental risk factors

More than 161,000 lung cancer deaths are projected to occur in the United States in 2008. Of these, an estimated 10 to 15% will be caused by factors other than active smoking, corresponding to 16,000 to 24,000 deaths annually. Thus lung cancer in never smokers would rank among the most common causes of cancer mortality in the United States if considered as a separate category. Slightly more than half of the lung cancers caused by factors other than active smoking occur in never smokers. As summarized in the accompanying article, lung cancers that occur in never smokers differ from those that occur in smokers in their molecular profile and response to targeted therapy. These recent laboratory and clinical observations highlight the importance of defining the genetic and environmental factors responsible for the development of lung cancer in never smokers. This article summarizes available data on the clinical epidemiology of lung cancer in never smokers, and several environmental risk factors that population-based research has implicated in the etiology of these cancers. Primary factors closely tied to lung cancer in never smokers include exposure to known and suspected carcinogens including radon, second-hand tobacco smoke, and other indoor air pollutants. Several other exposures have been implicated. However, a large fraction of lung cancers occurring in never smokers cannot be definitively associated with established environmental risk factors, highlighting the need for additional epidemiologic research in this area.

Estimation of the effects of smoking and DNA repair capacity on coefficients of a carcinogenesis model for lung cancer

Numerous prospective and retrospective studies have clearly demonstrated a dose-related increased lung cancer risk associated with cigarette smoking, with evidence also for a genetic component to risk. In this study, using the two-stage clonal expansion stochastic model framework, for the first time we investigated the roles of both genetic susceptibility and smoking history in the initiation, clonal expansion, and malignant transformation processes in lung carcinogenesis, integrating information collected by a case-control study and a large-scale prospective cohort study. Our results show that individuals with suboptimal DNA repair capacity have enhanced transition rates of key events in carcinogenesis.

Occupation, gender, race, and lung cancer

OBJECTIVE

To examine associations between occupation and lung cancer by gender and race.

METHODS

We used data from the Maryland Lung Cancer Study of nonsmall cell lung carcinoma (NSCLC), a multicenter case control study, to estimate odds ratios (ORs) of NSCLC in different occupations.

RESULTS

After adjusting for smoking, environmental tobacco smoke, and other covariates, NSCLC ORs among women but not men were elevated in clerical-sales, service, and transportation-material handling occupations; ORs were significantly increased in all three categories (OR [95% confidence interval]: 4.07 [1.44 to 11.48]; 5.15 [1.62 to 16.34]; 7.82 [1.08 to 56.25], respectively), among black women, but only in transportation-material handling occupations (OR [95% confidence interval[: 3.43 [1.02 to 11.50]) among white women.

CONCLUSIONS

Women, especially black women, in certain occupations had increased NSCLC ORs.

Landmarks in the history of cancer epidemiology

The application of epidemiology to cancer prevention is relatively new, although observations of the potential causes of cancer have been reported for more than 2,000 years. Cancer was generally considered incurable until the late 19th century. Only with a refined understanding of the nature of cancer and strategies for cancer treatment could a systematic approach to cancer prevention emerge. The 20th century saw the elucidation of clues to cancer causation from observed associations with population exposures to tobacco, diet, environmental chemicals, and other exogenous factors. With repeated confirmation of such associations, researchers entertained for the first time the possibility that cancer, like many of the infectious diseases of the time, might be prevented. By the mid-20th century, with antibiotics successfully addressing the majority of infectious diseases and high blood pressure treatment beginning to affect the prevalence of heart disease in a favorable direction, the focus of much of epidemiology shifted to cancer. The early emphasis was on exploring, in greater depth, the environmental, dietary, hormonal, and other exogenous exposures for their potential associations with increased cancer risk. The first major breakthrough in identifying a modifiable cancer risk factor was the documentation of an association between tobacco smoking and lung cancer. During the past four decades, epidemiologic studies have generated population data identifying risk factors for cancers at almost every body site, with many cancers having multiple risk factors. The development of technologies to identify biological molecules has facilitated the incorporation of these molecular manifestations of biological variation into epidemiologic studies, as markers of exposure as well as putative surrogate markers of cancer outcome. This technological trend has, during the past two decades, culminated in emphasis on the identification of genetic variants and their products as correlates of cancer risk, in turn, creating opportunities to incorporate the discipline of molecular/genetic epidemiology into the study of cancer prevention. Epidemiology will undoubtedly continue contributing to cancer prevention by using traditional epidemiologic study designs to address broad candidate areas of interest, with molecular/genetic epidemiology investigations honing in on promising areas to identify specific factors that can be modified with the goal of reducing risk.