Exposure to environmental tobacco smoke and the risk of lung cancer: a meta-analysis

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.

Evaluation of Population-Level Tobacco Control Interventions and Health Outcomes: A Systematic Review and Meta-Analysis

Importance

Smoking causes considerable noncommunicable diseases, perinatal morbidity, and mortality.

Objective

To investigate the associations of population-level tobacco-control policies with health outcomes.

Data Sources

PubMed, EMBASE, Web of Science, Cumulated Index to Nursing and Allied Health Literature, and EconLit were searched from inception to March 2021 (updated on 1 March 2022). References were manually searched.

Study Selection

Studies reporting on associations of population-level tobacco control policies with health-related outcomes were included. Data were analyzed from May to July 2022.

Data Extraction and Synthesis

Data were extracted by 1 investigator and cross-checked by a second investigator. Analyses were conducted using the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline.

Main Outcomes and Measures

The primary outcomes were respiratory system disease (RSD), cardiovascular disease (CVD), cancer, mortality, hospitalization, and health care utilization. The secondary outcomes were adverse birth outcomes, such as low birth weight and preterm birth. Random-effects meta-analysis was used to estimate pooled odds ratios (ORs) and 95% CIs.

Results

Of 4952 records identified, 144 population-level studies were included in the final analysis; 126 studies (87.5%) were of high or moderate quality. The most frequently reported policies were smoke-free legislation (126 studies), followed by tax or price increases (14 studies), multicomponent tobacco control programs (12 studies), and a minimum cigarette purchase age law (1 study). Smoke-free legislation was associated with decreased risk of all CVD events (OR, 0.90; 95% CI, 0.86-0.94), RSD events (OR, 0.83; 95% CI, 0.72-0.96), hospitalization due to CVD or RSD (OR, 0.91; 95% CI, 0.87-0.95), and adverse birth outcomes (OR, 0.94; 95% CI, 0.92-0.96). These associations persisted in all sensitivity and subgroup analyses, except for the country income category, for which a significant reduction was only observed in high-income countries. In meta-analysis, there was no clear association of tax or price increases with adverse health outcomes. However, for the narrative synthesis, all 8 studies reported statistically significant associations between tax increases and decreases in adverse health events.

Conclusions and Relevance

In this systematic review and meta-analysis, smoke-free legislation was associated with significant reductions in morbidity and mortality related to CVD, RSD, and perinatal outcomes. These findings support the need to accelerate the implementation of smoke-free laws to protect populations against smoking-related harm.

Secondhand and thirdhand smoke: a review on chemical contents, exposure routes, and protective strategies

Secondhand smoke (SHS: a mixture of sidestream and mainstream smoke) and thirdhand smoke (THS: made up of the pollutants that settle indoors after smoking in closed environments) are a significant public health concern. SHS and THS contain various chemicals which can be released into the air or settle on surfaces. At present, the hazards of SHS and THS are not as well documented. In this review, we describe the chemical contents of THS and SHS, exposure routes, vulnerable groups, health effects, and protective strategies. The literature search was conducted for published papers on September 2022 in Scopus, Web of Science, PubMed, and Google Scholar databases. This review could provide a comprehensive understanding of the chemical contents of THS and SHS, exposure routes, vulnerable groups, health effects, protective strategies, and future researches on environmental tobacco smoke.

On the triad of air PM pollution, pathogenic bioaerosols, and lower respiratory infection

Airborne particulate matter (PM) pollution, as a leading environmental health risk, causes millions of premature deaths globally every year. Lower respiratory infection (LRI) is a sensitive response to short-term exposure to outdoor PM pollution. The airborne transmission of etiological agents of LRI, as an important pathway for infection and morbidity, bridges the public health issues of air quality and pathogen infectivity, virulence, resistance, and others. Enormous efforts are underway to identify common pathogens and substances that are etiological agents for LRI and to understand the underlying toxicological and clinical basis of health effects by identifying mechanistic pathways. Seasonal variations and geographical disparities in the survival and infectivity of LRI pathogens are unsolved mysteries. Weather conditions in geographical areas may have a key effect, but also potentially connect LRI with short-term increases in ambient air PM pollution. Statistical associations show that short-term elevations in fine and coarse PM lead to increases in respiratory infections, but the causative agents could be chemical or microbiological and be present individually or in mixtures, and the interactions between chemical and microbiological agents remain undefined. Further investigations on high-resolution monitoring of airborne pathogens in relation to PM pollution for an integrated exposure-response assessment and mechanistic study are warranted. Improving our understanding of the spatiotemporal features of pathogenic bioaerosols and air pollutants and translating scientific evidence into effective policies is vital to reducing the health risks and devastating death toll from PM pollution.

Cumulative antitumor effect of bismuth lipophilic nanoparticles and cetylpyridinium chloride in inhibiting the growth of lung cancer

OBJECTIVE

To determine the combined antitumor effect of bismuth lipophilic nanoparticles (BisBAL NP) and cetylpyridinium chloride (CPC) on human lung tumor cells.

MATERIAL AND METHODS

The human lung tumor cells A549 were exposed to 1-100 µM BisBAL NP or CPC, either separately or in a 1:1 combination. Cell viability was measured with the PrestoBlue assay, the LIVE/DEAD assay, and fluorescence microscopy. The integrity and morphology of cellular microtubules were analyzed by immunofluorescence.

RESULTS

A 24-h exposure to 1 µM solutions reduced A549 growth with 21.5% for BisBAL NP, 70.5% for CPC, and 92.4% for the combination (p < 0.0001), while a 50 µM BisBAL NP/CPC mixture inhibited cell growth with 99% (p < 0.0001). BisBAL NP-curcumin conjugates were internalized within 30 min of exposure and could be traced within the nucleus of tumor cells within 2 h. BisBAL NP, but not CPC, interfered with microtubule organization, thus interrupting cell replication, similar to the action mechanism of docetaxel.

CONCLUSION

The growth inhibition of A549 human tumor cells by BisBAL NP and CPC was cumulative as of 1 µM. The BisBAL NP/CPC combination may constitute an innovative and cost-effective alternative for treating human lung cancer.

Neighborhood disadvantage and lung cancer risk in a national cohort of never smoking Black women

BACKGROUND

Compared to women of other races who have never smoked, Black women have a higher risk of lung cancer. Whether neighborhood disadvantage, which Black women experience at higher rates than other women, is linked to never-smoking lung cancer risk remains unclear. This study investigates the association of neighborhood disadvantage and lung cancer risk in Black never-smoking women.

METHODS AND MATERIALS

This research utilized data from the Black Women's Health Study, a prospective cohort of 59,000 Black women recruited from across the US in 1995 and followed by biennial questionnaires. Associations of lung cancer incidence with neighborhood-level factors (including two composite variables derived from Census Bureau data: neighborhood socioeconomic status and neighborhood concentrated disadvantage), secondhand smoke exposure, and PM_2.5 were estimated using Fine-Gray subdistribution hazard models.

RESULTS

Among 37,650 never-smokers, 77 were diagnosed with lung cancer during follow-up from 1995 to 2018. The adjusted subdistribution hazard ratio (sHR) of lung cancer incidence with ten unit increase in neighborhood concentrated disadvantage index was 1.30 (95 % CI: 1.04, 1.63, p = 0.023). Exposure to secondhand smoke at work was associated with increased risk (sHR = 1.93, 95 % CI: 1.21, 3.10, p = 0.006), but exposure to secondhand smoke at home and PM_2.5 was not.

CONCLUSION

Worse neighborhood concentrated disadvantage was associated with increased lung cancer risk in Black women who never smoked. These findings suggest that non-tobacco-related factors in disadvantaged neighborhoods may be linked to lung cancer risk in Black women and that these factors must be understood and targeted to achieve health equity.

Screening rate and influential factors of lung cancer with low-dose computed tomography in Asian population: a systematic review and meta-analysis

BACKGROUND

There are currently no studies synthesizing the screening rate and influential factors of low-dose computed tomography (LDCT)-screened lung cancer in Asian population.

METHODS

A systematic review was conducted, using both English and Chinese language databases on March, 2019. The pooled screening rate and estimated odds ratios (ORs) of influential factors were analyzed using random effects models. Subgroup and meta-regression analyses were also employed to explore the heterogeneity.

RESULTS

The pooled LDCT lung cancer screening rate was 1.12% (95% confidence interval (CI): 0.94%, 1.32%), and increased with age. Adenocarcinoma and stage I lung cancer had higher screening rates. Analysis of influential factors in the general population showed that female and elder age (≥50 years) were significantly influencing LDCT lung cancer screening rate (for female, OR = 1.32, 95% CI: 1.15-1.52; for adults ≥ 50 years, OR = 1.94, 95% CI: 1.52-2.49). Meta-regression analysis indicated that the heterogeneity maybe significantly correlated with the sample size, risk population and source of population.

CONCLUSIONS

Unlike European and American populations, female and adults > 50 years rather than smoking adults were positively associated with screening rate in Asian populations. It is important to further study the benefits of lung cancer screening with LDCT in Asian populations.

Cytochrome P450 2A6 whole-gene deletion (CYP2A6*4) polymorphism reduces risk of lung cancer: A meta-analysis

INTRODUCTION

Lung cancer is the most commonly diagnosed cancer worldwide and is the leading cause of cancer death. Smoking is a major contributor to the pathogenesis of lung cancer. Cytochrome P450 2A6 (CYP2A6) is responsible for the metabolic activation of most tobacco carcinogens. CYP2A6 genetic polymorphism can cause variations in the human metabolism of xenobiotics. We performed this meta-analysis to determine the association between whole-gene CYP2A6 deletion polymorphism (CYP2A6*4) and lung cancer risk.

METHODS

The PubMed, SAGE, Science Direct, the Cochrane Library and Ovid databases were searched for observational studies before October 2018. Methodological quality was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS).

RESULTS

Nine case-control studies involving 4385 lung cancer cases and 4142 controls were included in the analysis. The random-effects model was used to combine results from individual studies. The pooled odds ratio was 0.39 (95% CI: 0.27-0.56). There was no heterogeneity across studies (χ2=2.49, p=0.96, I2=0%).

CONCLUSIONS

Current evidence from the case-control studies suggests that the CYP2A6 whole-gene deletion polymorphism decreases the risk of lung cancer. Further research is needed to identify any potential confounding factors that may impact this association.

Epidemiology of lung cancer and lung cancer screening programs in China and the United States

Lung cancer is a heterogeneous disease that is impacted by environmental exposures and by constitutional genetic or epigenetic susceptibilities to disease development and progression. The United States and China have distinct and diverse populations and geographic environmental exposures that contribute to unique patterns of lung cancer incidence and mortality. In this paper, the authors compare trends of incidence and mortality of lung cancer in the US and China, and the impact on lung cancer screening programs in the two countries. It is worth noting that the mortality of lung cancer in the US has decreased gradually while in China it is still increasing over recent years. While decreasing smoking prevalence and the impact of clean air legislation have helped to mitigate the trend in the US relative to China, the increasingly widespread implementation of lung cancer chest CT screening is expected to impact lung cancer incidence and mortality in both countries. Currently there are few studies to compare the environmental and genetic risk factors for US and Chinese populations with regards to lung cancer incidence and mortality. The authors discuss the impact of gender and exposure risks, mainly smoking and environmental pollutants. Of high importance is the incidence of lung cancer in never smokers that is significantly higher in China than in the United States; this is particularly notable in women. These data suggest inclusion of ambient air pollution exposure and gender into lung cancer risk prognostic models to better capture high-risk individuals, especially for non-smoking women.

Tobacco smoking and trends in histological subtypes of female lung cancer at the Cancer Hospital of the Chinese Academy of Medical Sciences over 13 years

Background

Lung cancer is the leading cause of cancer mortality among women in China, and incidence and mortality continue to rise despite the fact that smoking prevalence is very low among Chinese women.

Aim

This study investigated tobacco smoking and trends in histological subtypes of female lung cancer in a central cancer hospital in China.

Methods

Demographic, smoking history and histological information on female lung cancer patients diagnosed or treated from 2000 to 2012 was collected from the Cancer Hospital, Chinese Academy of Medical Science (CHCAMS). The classification of histological subtypes and clinical stages were conducted using the ICD‐O‐3 and Eighth AJCC Cancer Staging Manuals. Time‐trends of histological subtypes were analyzed based on annual percentage change (APC).

Results

Overall, 5870 female cases of lung cancer were included in the analysis. The number of female lung cancer patients increased from 509 (2000–2002) to 1744 (2011–2012). The most common histological type of lung cancer was adenocarcinoma (ADC) (72.93%), followed by small cell lung cancer (SCLC) (11.06%), squamous cell carcinoma (SCC) (8.38%) and other (7.63%). Among smokers, the proportion of SCC decreased from 40.5% to 23.7% (P = 0.005), while ADC increased from 35.7% to 50.7% (P = 0.009). In non‐smokers, ADC increased from 63.1% to 80.6% (P = 0.006) and SCC decreased from 13.6% to 4.5% (P = 0.016). Among SCC cases, smokers made up a larger proportion of early stage (I/II: 47.1%) compared with late stages (III, 34.3%; IV, 18.6%).

Conclusion

The number of female lung cancer patients has increased in CHCAMS. In both smoking and non‐smoking cases, the proportion of adenocarcinoma increased. Squamous cell carcinomas were more likely to be diagnosed in early stages among smokers.

Smoking and Lung Cancer Mortality in the United States From 2015 to 2065: A Comparative Modeling Approach

BACKGROUND

Tobacco control efforts implemented in the United States since the 1960s have led to considerable reductions in smoking and smoking-related diseases, including lung cancer.

OBJECTIVE

To project reductions in tobacco use and lung cancer mortality from 2015 to 2065 due to existing tobacco control efforts.

DESIGN

Comparative modeling approach using 4 simulation models of the natural history of lung cancer that explicitly relate temporal smoking patterns to lung cancer rates.

SETTING

U.S. population, 1964 to 2065.

PARTICIPANTS

Adults aged 30 to 84 years.

MEASUREMENTS

Models were developed using U.S. data on smoking (1964 to 2015) and lung cancer mortality (1969 to 2010). Each model projected lung cancer mortality by smoking status under the assumption that current decreases in smoking would continue into the future (status quo trends). Sensitivity analyses examined optimistic and pessimistic scenarios.

RESULTS

Under the assumption of continued decreases in smoking, age-adjusted lung cancer mortality was projected to decrease by 79% between 2015 and 2065. Concomitantly, and despite the expected growth, aging, and longer life expectancy of the U.S. population, the annual number of lung cancer deaths was projected to decrease from 135 000 to 50 000 (63% reduction). However, 4.4 million deaths from lung cancer are still projected to occur in the United States from 2015 to 2065, with about 20 million adults aged 30 to 84 years continuing to smoke in 2065.

LIMITATION

Projections assumed no changes to tobacco control efforts in the future and did not explicitly consider the potential effect of lung cancer screening.

CONCLUSION

Tobacco control efforts implemented since the 1960s will continue to reduce lung cancer rates well into the next half-century. Additional prevention and cessation efforts will be required to sustain and expand these gains to further reduce the lung cancer burden in the United States.

PRIMARY FUNDING SOURCE

National Cancer Institute.

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.

Impact of smoking on efficacy of PD-1/PD-L1 inhibitors in non-small cell lung cancer patients: a meta-analysis

Background

Smoking status is associated with the efficacy of non-small cell lung cancer (NSCLC) treatment. Latest clinical trials have depicted the difference in the effectiveness of programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) inhibitors in smokers and nonsmokers. However, the lack of statistical power in these trials prevented a final conclusion. The authors postulated that the efficacy of PD-1/PD-L1 inhibitors correlated with smoking status.

Materials and methods

Clinical trials evaluating PD-1 inhibitors versus chemotherapies in smokers and nonsmokers were included. The hazard ratios (HRs) and 95% confidence intervals (CIs) of overall survival (OS) and progression-free survival (PFS) were used.

Results

A total of 1,981 patients from three Phase III randomized controlled trials (RCTs) were included. PD-1/PD-L1 inhibitors significantly prolonged the OS (HR, 0.69; 95% CI, 0.60–0.78) and PFS (HR, 0.55; 95% CI, 0.43–0.67; P = 0.027) in smoking patients versus chemotherapy. However, among nonsmoking patients, no significant improved OS and PFS were observed compared with chemotherapy.

Conclusion

PD-1 inhibitors were more efficacious in smoking NSCLC patients compared with chemotherapy. No better survival of nonsmoking patients was observed in the treatment of PD-1 inhibitors than chemotherapy. Difference in the efficacy of PD-1 treatment should be taken into consideration in the future guidelines and clinical practice.

The increasing challenge of never smokers with adenocarcinoma lung: Need to look beyond tobacco exposure

BACKGROUND

Lung cancer continues to remain as one of the leading causes of morbidity and mortality worldwide, despite the decreasing trends in smoking prevalence worldwide. An earlier study from the authors' institute reported the increasing trends of "Nonsmoking associated lung cancers."

MATERIALS AND METHODS

All consecutive histologically confirmed patients with lung cancer who presented to the outpatient department over a year (November 2014-October 2015) were included in this current prospective study.

RESULTS

Seven hundred and thirteen patients presented with clinicoradiologically suspicious findings of lung cancer in the said period. A pathological confirmation of lung cancer could be ascertained in 495 patients, and this cohort was further analyzed. The mean age of presentation was 57.76 years; the male to female ratio was approximately 2.5:1. Interestingly, 55.35% of the patients were nonsmokers. Adenocarcinoma (63%) was the predominant histology. Never smokers, both among men (P = 0.02) and women (P = 0.001), presented more frequently with adenocarcinoma histology. Further, 84.9% (45/53) of rural and 76.1% (19/25) of urban women who were never smokers reported exposure to indoor air pollution (secondhand smoke/fuel used for cooking purposes) which was significantly associated with adenocarcinoma histology.

CONCLUSION

Our study confirmed our initial observation of the changing epidemiology of lung cancer in the Indian subcontinent, paralleling the global trends of rise in adenocarcinoma. Lung cancer in never smokers outnumbering that among smokers was another interesting observation. The take-home message for both the clinicians as well as the policymakers is to study factors beyond tobacco exposure to understand the direction of the current lung cancer epidemic.

Lung cancer in the Indian subcontinent

Smoking tobacco, both cigarettes and beedis, is the principal risk factor for causation of lung cancer in Indian men; however, among Indian women, the association with smoking is not strong, suggesting that there could be other risk factors besides smoking. Despite numerous advances in recent years in terms of diagnostic methods, molecular changes, and therapeutic interventions, the outcomes of the lung cancer patients remain poor; hence, a better understanding of the risk factors may impact the preventive measures to be implemented at the community level. There is a lack of comprehensive data on lung cancer in India. In this review, we attempt to collate the available data on lung cancer from India.

Secondhand smoke exposure and risk of lung cancer in Japan: a systematic review and meta-analysis of epidemiologic studies

OBJECTIVE

Systematic evaluation of the association between secondhand smoke exposure and lung cancer in Japan has yet to be conducted. Here, we performed a systematic review and meta-analysis of the relationship between secondhand smoke and lung cancer in Japanese non-smokers.

METHODS

Relevant studies were collected from the MEDLINE and Ichushi Web databases using a combination of search terms and Medical Subject Headings. Eligible studies were identified, and relative risks or odds ratios were extracted to calculate pooled risk estimates. This procedure was performed independently by at least two authors. Stratified analyses were carried out according to study design, publication year, and whether or not potential confounding variables were accounted for. The presence of publication bias was assessed via funnel plots.

RESULTS

We identified four cohort studies and five case-control studies. Quantitative synthesis was conducted only for secondhand smoke exposure in the home during adulthood. Of the 12 populations included in meta-analysis, positive secondhand smoke exposure-lung cancer associations were observed in 11, whereas an inverse association was found in the remaining 1. The pooled relative risk of lung cancer associated with secondhand smoke exposure was 1.28 (95% confidence interval: 1.10-1.48). We found no evidence of publication bias, and a significant association remained even when potentially missing studies were included (pooled relative risk: 1.26; 95% confidence interval: 1.09-1.46). The results were stable across different subgroup analyses, including by study design, publication year, and when adjusting for confounding variables.

CONCLUSIONS

Secondhand smoke exposure in the home during adulthood results in a statistically significant increase in the risk of lung cancer.

A Retrospective Study of Nail Squamous Cell Carcinoma at 2 Institutions

BACKGROUND

Squamous cell carcinoma (SCC) of the nail is infrequently reported in the medical literature and its causes are poorly understood. Studies have shown strong associations with immunosuppression, tobacco use, toxin/radiation exposure, and trauma. Common treatments include Mohs surgery and digital amputation.

OBJECTIVE

Review a series of nail SCCs treated at 2 institutions. Outcomes evaluated included rates of recurrence and disease progression/metastasis after treatment.

MATERIALS AND METHODS

A retrospective review of patients treated between 2005 and 2008. Medical record review and phone call follow-up using a standardized questionnaire were used.

RESULTS

Forty-two tumors were identified in 34 patients. Twenty-seven patients were male (79% CI, 62%-91%) and most tumors were located on the fingernails (39/42; 91% CI, 81%-99%). Twenty-four of 39 tumors (62% CI, 45%-77%) were on the nondominant hand. The middle third finger was the most frequent digit affected (16/42). Common symptoms reported were nail dystrophy (31/42; 74% CI, 58%-86%), followed by onycholysis (22/42; 52% CI, 36%-68%). Most tumors (35/42; 83% CI, 69%-93%) were treated with Mohs surgery.

CONCLUSION

Nail SCC is found nearly exclusively in adults and predominantly in men. There are multiple effective treatment possibilities including Mohs surgery, distal digital amputation, and early evidence suggesting radiotherapy.

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.

Epidemiology of Lung Cancer in Korea: Recent Trends

Lung cancer causes the most cancer deaths in Korea. Although the smoking rate has begun to decrease, the prevalence of lung cancer is still increasing. We reviewed the national lung cancer registry data and the data published about lung cancer in Korea. In 2012, the crude incidence rate of lung cancer was 43.9 per 100,000. The age-standardized mortality rate of lung cancer was 19.8 per 100,000. The 5-year relative survival rate for lung cancer was 11.3% from 1993 to 1995 and increased to 21.9% in the period from 2008 to 2012. Lung cancer occurring in never-smokers was estimated to increase in Korea. Adenocarcinoma is steadily increasing in both women and men and has replaced squamous cell carcinoma as the most common type of lung cancer in Korea. In patients with adenocarcinoma, the frequency of EGFR mutations was 43% (range, 20%–56%), while that of the EMK4-ALK gene was less than 5%.

Epidemiology of Lung Cancer

Lung cancer continues to be one of the most common causes of cancer death despite understanding the major cause of the disease: cigarette smoking. Smoking increases lung cancer risk 5- to 10-fold with a clear dose-response relationship. Exposure to environmental tobacco smoke among nonsmokers increases lung cancer risk about 20%. Risks for marijuana and hookah use, and the new e-cigarettes, are yet to be consistently defined and will be important areas for continued research as use of these products increases. Other known environmental risk factors include exposures to radon, asbestos, diesel, and ionizing radiation. Host factors have also been associated with lung cancer risk, including family history of lung cancer, history of chronic obstructive pulmonary disease and infections. Studies to identify genes associated with lung cancer susceptibility have consistently identified chromosomal regions on 15q25, 6p21 and 5p15 associated with lung cancer risk. Risk prediction models for lung cancer typically include age, sex, cigarette smoking intensity and/or duration, medical history, and occupational exposures, however there is not yet a risk prediction model currently recommended for general use. As lung cancer screening becomes more widespread, a validated model will be needed to better define risk groups to inform screening guidelines.

Hazard Ratio of Smoking on Lung Cancer in Korea According to Histological Type and Gender

PURPOSE

Using nationwide cancer incidence data, we examined whether the strength of the association of cigarette smoking with lung cancer risk differs according to major histological type and gender, taking account of other risk factors in the Korean population.

METHODS

The study population derived from government employees and teachers aged 20 years and over who participated in a national health examination program in 1998 or 1999. Total study subjects were 1,357,447. After excluding 1556 subjects who were treated with lung cancer during 1998-2000, we restricted our analysis to 1,355,891 cases. We followed up those 1,355,891 subjects who were cancer-free at baseline until December 31, 2010. The incident cancer cases were identified from the Korea Central Cancer Registry, which is a nationwide hospital-based cancer registry system that includes 94 % of the university hospitals and 96 % of the resident training hospitals of the country.

RESULTS

A higher risk for having ever smoked was observed for squamous-cell and small-cell carcinoma in both men and women. Heavy and long-term smokers were at higher risk for these carcinomas. Significant associations with quantity and duration-related factors were observed mainly among men. These findings indicate that smoking is closely related to the risk of squamous-cell and small-cell carcinoma among women as well as men. However, the magnitude of smoking-related lung cancer risk is likely to differ between men and women.

CONCLUSION

The hazard ratios for all types of lung cancer were significantly higher in male current smokers than in male never smokers. In case of women, the hazard ratios for adenocarcinoma were not different between current smokers and never smokers. The hazard ratios we found, however, were lower than those reported in Western countries and in Korea, but consistent with those reported in North-eastern Asian countries.

Association Between the CYP1B1 Polymorphisms and Lung Cancer Risk: A Meta-Analysis

The previously published data on the association between the cytochrome P450 1B1 Leu432Val, Asn453Ser, and Ala119Ser polymorphisms and lung cancer risk have remained controversial. Hence, we performed a meta-analysis to investigate the association between cytochrome P450 1B1 Leu432Val, Asn453Ser, and Ala119Ser polymorphisms and lung cancer risk under different inheritance models. A total of 22 studies were identified, including 2881 cases and 3653 controls for Leu432Val polymorphism (from 13 studies), 3009 cases and 3887 controls for Asn453Ser polymorphism (from 5 studies), and 1301 cases and 2045 controls for Ala119Ser polymorphism (from 4 studies). Overall, significant association was observed between cytochrome P450 1B1 Leu432Val polymorphism and lung cancer risk (dominant model: odds ratio = 1.29, 95% confidence interval = 1.08-1.53; recessive model: odds ratio = 1.21, 95% confidence interval = 1.05-1.39; additive model: odds ratio = 1.43, 95% confidence interval = 1.21-1.69) when all the eligible studies were pooled into the meta-analysis. In the further stratified and sensitivity analyses, significantly increased lung cancer risk was also observed in caucasians and smokers. No significant association was observed between cytochrome P450 1B1Asn453Ser and Ala119Ser polymorphisms and lung cancer risk in overall analysis. In summary, this meta-analysis suggests that cytochrome P450 1B1Leu432Val polymorphism is associated with increased lung cancer risk in caucasians and smokers.

A systematic review of secondhand tobacco smoke exposure and smoking behaviors: Smoking status, susceptibility, initiation, dependence, and cessation

OBJECTIVES

To examine the association between secondhand tobacco smoke exposure (SHSe) and smoking behaviors (smoking status, susceptibility, initiation, dependence, and cessation).

METHODS

Terms and keywords relevant to smoking behaviors and secondhand tobacco smoke exposure were used in a search of the PubMed database. Searches were limited to English language peer-reviewed studies up till December 2013. Included papers: a) had clearly defined measures of SHSe and b) had clearly defined measures of outcome variables of interest. A total of 119 studies were initially retrieved and reviewed. After further review of references from the retrieved studies, 35 studies were finally selected that met all eligibility criteria.

RESULTS

The reviewed studies consisted of thirty-five (89.7%) studies with differing measures of SHSe (including questionnaire and biological measures) and varying definitions of main outcome variables of interest between studies. The majority of the studies (77%) were cross-sectional in nature. The majority of studies found that SHSe was associated with greater likelihood of being a smoker, increased susceptibility and initiation of smoking, greater nicotine dependence among nonsmokers, and poorer smoking cessation.

CONCLUSIONS

The review found positive associations between SHSe and smoking status, susceptibility, initiation and nicotine dependence and a negative association with smoking cessation. In light of design limitations, future prospective and clinical studies are needed to better understand the mechanisms whereby SHSe influences smoking behaviors.

Four polymorphisms in the cytochrome P450 1A2 (CYP1A2) gene and lung cancer risk: a meta-analysis

BACKGROUND

Previous published data on the association between CYP1A2 rs762551, rs2069514, rs2069526, and rs2470890 polymorphisms and lung cancer risk have not allowed a definite conclusion. The present meta-analysis of the literature was performed to derive a more precise estimation of the relationship.

MATERIALS AND METHODS

8 publications covering 23 studies were selected for this meta-analysis, including 1,665 cases and 2,383 controls for CYP1A2 rs762551 (from 8 studies), 1,456 cases and 1,792 controls for CYP1A2 rs2069514 (from 7 studies), 657 cases and 984 controls for CYP1A2 rs2069526 (from 5 studies) and 691 cases and 968 controls for CYP1A2 rs2470890 (from 3 studies).

RESULTS

When all the eligible studies were pooled into the meta-analysis for the CYP1A2 rs762551 polymorphism, significantly increased lung cancer risk was observed in the dominant model (OR=1.21, 95 % CI=1.00-1.46). In the subgroup analysis by ethnicity, significantly increased risk of lung cancer was observed in Caucasians (dominant model: OR=1.29, 95%CI=1.11-1.51; recessive model: OR=1.33, 95%CI=1.01-1.75; additive model: OR=1.49, 95%CI=1.12-1.98). There was no evidence of significant association between lung cancer risk and CYP1A2 rs2069514, s2470890, and rs2069526 polymorphisms.

CONCLUSIONS

In summary, this meta-analysis indicates that the CYP1A2 rs762551 polymorphism is linked to an increased lung cancer risk in Caucasians. Moreover, our work also points out the importance of new studies for rs2069514 associations in lung cancer, where at least some of the covariates responsible for heterogeneity could be controlled, to obtain a more conclusive understanding about the function of the rs2069514 polymorphism in lung cancer development.

Application environmental epidemiology to vehicular air pollution and health effects research

Vehicular pollution is one of the major contributors to the air pollution in urban areas and perhaps and accounts for the major share of anthropogenic green-house gases such as carbon dioxide, carbon monoxide, nitrogen oxides. Knowledge of human health risks related to environmental exposure to vehicular pollution is a current concern. Analyze the range health effects are attributed varied constituents of vehicular air pollution examine evidence for a causal association to specific health effect. In many instances scenario involves exposure to very low doses of putative agents for extended periods, sometimes the period could mean over a lifetime of an individual and yet may result in small increase in health risk that may be imperceptible. Secondary data analysis and literature review. In environmental exposures, traditional epidemiological approaches evaluating mortality and morbidity indicators display many limiting factors such as nonspecificity of biological effects latency time between exposure and magnitude of the effect. Long latency period between exposure and resultant disease, principally for carcinogenic effects and limitation of epidemiological studies for detecting small risk increments. The present paper discusses the methodological challenges in studying vehicular epidemiology and highlights issues that affect the validity of epidemiological studies in vehicular pollution.

Does household use of biomass fuel cause lung cancer? A systematic review and evaluation of the evidence for the GBD 2010 study

BACKGROUND

Around 2.4 billion people use traditional biomass fuels for household cooking or heating. In 2006, the International Agency for Research on Cancer (IARC) concluded emissions from household coal combustion are a Group 1 carcinogen, while those from biomass were categorised as 2A due to epidemiologic limitations. This review updates the epidemiologic evidence and provides risk estimates for the 2010 Global Burden of Disease study.

METHODS

Searches were conducted of 10 databases to July 2012 for studies of clinically diagnosed or pathologically confirmed lung cancer associated with household biomass use for cooking and/or heating.

FINDINGS

Fourteen eligible studies of biomass cooking or heating were identified: 13 had independent estimates (12 cooking only), all were case-control designs and provided 8221 cases and 11 342 controls. The ORs for lung cancer risk with biomass for cooking and/or heating were OR 1.17 (95% CI 1.01 to 1.37) overall, and 1.15 (95% CI 0.97 to 1.37) for cooking only. Publication bias was not detected, but more than half the studies did not explicitly describe a clean reference category. Sensitivity analyses restricted to studies with adequate adjustment and a clean reference category found ORs of 1.21 (95% CI 1.05 to 1.39) for men (two reports, compiling five studies) and 1.95 (95% CI 1.16 to 3.27) for women (five reports, compiling eight studies). Exposure-response evidence was seen for men, and higher risk for women in developing compared with developed countries, consistent with higher exposures in the former.

CONCLUSIONS

There is now stronger evidence for biomass fuel use causing lung cancer, but future studies need better exposure assessment to strengthen exposure-response evidence.

Behavioral and Physiological Responses to Nicotine Patch Administration Among Nonsmokers Based on Acute and Chronic Secondhand Tobacco Smoke Exposure

INTRODUCTION

Despite the large amount that is known about the physical health effects of secondhand tobacco smoke (SHS) exposure, little is known about the behavioral health effects. Nicotine, the principle psychoactive substance in SHS, elicits subjective mood and physiological responses in nonsmokers. However, no studies have examined the subjective mood or physiological responses to nicotine in nonsmokers while accounting for prior chronic or acute SHS exposure.

METHODS

A 7-mg nicotine patch was administered to 17 adult nonsmokers for 2 hr. Main outcome measures obtained at ½ hr, 1 hr, and 2 hr were subjective behavioral drug effects (based on eleven 10-cm Visual Analog Scales [VASs]) and the physiological measures of heart rate, blood pressure, and serum nicotine levels. Analysis of outcome data was based on participants' chronic (using hair nicotine) or acute (using saliva cotinine) SHS exposure.

RESULTS

Greater chronic SHS exposure was negatively associated with pleasurable responses to nicotine administration ("drug feels good" score at 2-hr time point, Spearman's ρ = -.65, p < .004), whereas greater acute SHS exposure was associated with positive responses ("like feeling of drug" score at 2-hr time point, Spearman's ρ = .63, p < .01). There were no associations between chronic or acute exposure and physiological changes in response to nicotine administration.

DISCUSSION

The findings of this study may be useful in providing preliminary empirical data for future explorations of the mechanism whereby SHS exposure can influence behavioral outcomes in nonsmokers. Such studies can inform future interventions to reduce the physical and behavioral health risks associated with SHS exposure.

The potential role of lung microbiota in lung cancer attributed to household coal burning exposures

Bacteria influence site-specific disease etiology and the host's ability to metabolize xenobiotics, such as polycyclic aromatic hydrocarbons (PAHs). Lung cancer in Xuanwei, China has been attributed to PAH-rich household air pollution from burning coal. This study seeks to explore the role of lung microbiota in lung cancer among never smoking Xuanwei women and how coal burning may influence these associations. DNA from sputum and buccal samples of never smoking lung cancer cases (n = 8, in duplicate) and controls (n = 8, in duplicate) in two Xuanwei villages was extracted using a multi-step enzymatic and physical lysis, followed by a standardized clean-up. V1-V2 regions of 16S rRNA genes were PCR-amplified. Purified amplicons were sequenced by 454 FLX Titanium pyrosequencing and high-quality sequences were evaluated for diversity and taxonomic membership. Bacterial diversity among cases and controls was similar in buccal samples (P = 0.46), but significantly different in sputum samples (P = 0.038). In sputum, Granulicatella (6.1 vs. 2.0%; P = 0.0016), Abiotrophia (1.5 vs. 0.085%; P = 0.0036), and Streptococcus (40.1 vs. 19.8%; P = 0.0142) were enriched in cases compared with controls. Sputum samples had on average 488.25 species-level OTUs in the flora of cases who used smoky coal (PAH-rich) compared with 352.5 OTUs among cases who used smokeless coal (PAH-poor; P = 0.047). These differences were explained by the Bacilli species (Streptococcus infantis and Streptococcus anginosus). Our small study suggests that never smoking lung cancer cases have differing sputum microbiota than controls. Further, bacteria found in sputum may be influenced by environmental exposures associated with the type of coal burned in the home.

Correlates of secondhand tobacco smoke exposure among individuals with a history of substance use and/or psychiatric disorders participating in a tobacco treatment program in Vancouver, Canada

Individuals with substance use (SUD) and/or psychiatric disorders (PD) are disproportionately affected by tobacco use; yet, little is known about secondhand tobacco smoke (SHS) exposure in these populations. An analysis of existing data examined SHS exposure among 497 smokers in community clinics in Vancouver, Canada. Seventy-percent of the participants reported SHS exposure. In sex-stratified multivariate logistic regression analyses correlates of SHS exposure among women were not having a history of using evidence-based smoking cessation treatment and using a single substance (as compared to a polysubstance use history); whereas among men, a history of a respiratory illness and higher nicotine dependence were associated with SHS exposure. Despite limitations about the measures of SHS exposure used in the study, these findings suggest a need to further determine the risks associated with SHS exposure and tobacco use among individuals with SUD and/or PD within mental health and addictions treatment settings.

Smokers still underestimate the risks posed by secondhand smoke: a repeated cross-sectional study

BACKGROUND

Little is known about risk perception of secondhand smoke (SHS) and its changes over time. The aim of the study was to examine the role of smoking status and demographics on perceiving a range of health risks of SHS exposure and their trends over time among a representative sample of the Irish general population.

METHODS

This study included 2 repeated cross-sectional samples of Irish adults in 1999 (n = 1,240) and 2006 (n = 1,000), in addition to a representative sample of General Practitioners (2006: n = 248), sampled as a health care professional's view on SHS risk. Participants were asked to consider whether a nonsmoker, exposed to SHS, is at an increased risk of asthma, lung cancer, heart disease, bronchitis, diabetes, and ear infections in children.

RESULTS

There was a significant increase in the general population's risk perception of SHS for asthma, lung cancer, heart disease, and bronchitis from 1999 to 2006. Not even half of the general population in 1999 and in 2006 perceived a risk for the development of ear infections in children with SHS exposure (45% in 1999, 46% in 2006). With the exception of ear infections in children in 2006, the risk perception of all diseases differed significantly by smoking status; smokers' risk perception of SHS was significantly lower. Encouraging results suggest that the differences in risk perception between smokers and nonsmokers have decreased.

CONCLUSION

Risk perception of SHS exposure has improved as has the gap in perception between smokers and nonsmokers. This research points to a lack of awareness among the general population of the risk perception of SHS exposure to children.

Differences in age-standardized mortality rates for avoidable deaths based on urbanization levels in Taiwan, 1971-2008

The World is undergoing rapid urbanization, with 70% of the World population expected to live in urban areas by 2050. Nevertheless, nationally representative analysis of the health differences in the leading causes of avoidable mortality disaggregated by urbanization level is lacking. We undertake a study of temporal trends in mortality rates for deaths considered avoidable by the Concerted Action of the European Community on Avoidable Mortality for four different levels of urbanization in Taiwan between 1971 and 2008. We find that for virtually all causes of death, age-standardized mortality rates (ASMRs) were lower in more urbanized than less urbanized areas, either throughout the study period, or by the end of the period despite higher rates in urbanized areas initially. Only breast cancer had consistently higher AMSRs in more urbanized areas throughout the 38-year period. Further, only breast cancer, lung cancer, and ischemic heart disease witnessed an increase in ASMRs in one or more urbanization categories. More urbanized areas in Taiwan appear to enjoy better indicators of health outcomes in terms of mortality rates than less urbanized areas. Access to and the availability of rich healthcare resources in urban areas may have contributed to this positive result.

Exposure to environmental tobacco smoke (ETS) and risk of lung cancer in Montreal: a case-control study

BACKGROUND

The objective of the present study was to examine the association between environmental tobacco smoke (ETS) and risk of lung cancer among never smokers, defined as subjects who smoked less than 100 cigarettes in their lifetime.

METHODS

We conducted a population-based case-control study on lung cancer in Montreal, Canada (1996-2000) including 1,203 cases and 1513 controls. The present analysis is restricted to the 44 cases and 436 population controls who reported never smoking and completed the questionnaire on lifetime ETS exposure. Collected information included duration and intensity of exposure from multiple sources: inside home (parents, spouses, roommates and any other co-resident) and outside homes (in vehicles, social settings, and workplace). Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated between ETS and lung cancer, adjusting for age, sex, socioeconomic status (SES), and proxy respondent.

RESULTS

Overall there was no association between ETS cumulative exposure from all sources (measured in pack-years) and lung cancer: OR = 0.98 (95%CI: 0.40-2.38), comparing upper with lower tertiles of exposure. While there were no elevated ORs associated with ever having lived with parents who smoked (OR = 0.62; 95%CI: 0.32-1.21) or with spouses who smoked (OR = 0.39; 95%CI: 0.18-0.85), ETS exposure from sources outside homes was associated with a slight, although non-significant increased risk: OR = 2.30 (95%CI: 0.85-6.19) for the upper 50% exposed. There were no clear differences in ORs by age at exposure to ETS or by histologic type of tumour, though numbers of subjects in subgroup analyses were too small to provide reliable estimates.

CONCLUSION

No clear association between lifetime ETS exposure from all sources and increased risk of lung cancer was found in the current study.

Smoking bans linked to lower hospitalizations for heart attacks and lung disease among medicare beneficiaries

Policies limiting exposure to cigarette smoke have been associated with reduced hospitalizations for heart attacks, but little is known about the impact of smoking bans on other health conditions and whether findings from individual communities generalize to other areas. We investigated the association between smoking bans targeting workplaces, restaurants, and bars passed throughout the United States during 1991-2008 and hospital admissions for smoking-related illnesses-acute myocardial infarction and chronic obstructive pulmonary disease-among Medicare beneficiaries age sixty-five or older. Risk-adjusted hospital admission rates for acute myocardial infarction fell 20-21 percent thirty-six months following implementation of new restaurant, bar, and workplace smoking bans. Admission rates for chronic obstructive pulmonary disease fell 11 percent where workplace smoking bans were in place and 15 percent where bar smoking bans were present. By contrast, very little effect was found for hospitalization for gastrointestinal hemorrhage and hip fracture-two conditions largely unrelated to smoking and examined as points of comparison. These findings provide further support for the public health benefits of laws that limit exposure to tobacco smoke.

Association between glutathione S-transferase T1 null genotype and risk of lung cancer: a meta-analysis of 55 studies

The relationship between glutathione S-transferase T1 (GSTT1) gene polymorphism and the risk of lung cancer from the published reports are still conflicting. This study was conducted to evaluate the relationship between GSTT1 polymorphism and the risk of lung cancer. A comprehensive research was conducted through the databases, and 55 studies were recruited into this meta-analysis for the association of null genotype of GSTT1 with lung cancer susceptibility, consisting of 15,140 patients with lung cancer and 16,662 controls. There was a significant association between GSTT1 null genotype and lung cancer risk in the overall populations (OR = 1.138, 95% CI = 1.032-1.255, P heterogeneity = 0.000, P = 0.009). Furthermore, GSTT1 null genotype was associated with the lung cancer risk in Asians (OR = 1.469, 95% CI = 1.228-1.757, P heterogeneity = 0.000, P = 0.000). However, GSTT1 null genotype was not associated with the risk of lung cancer in Caucasians and Africans. In conclusion, GSTT1 null genotype is associated with the lung cancer in overall populations and in Asians.

Temporal trend analysis of avoidable mortality in Taiwan, 1971-2008: overall progress, with areas for further medical or public health investment

BACKGROUND

Avoidable mortality (AM), or "unnecessary untimely death," is considered an indicator of health care quality. We investigated trends in the age-standardized mortality rates (ASMRs) and associated standard expected years of life lost (SEYLL) for deaths amenable to medical care or public health measures in Taiwan from 1971-2008, with an emphasis on identifying areas where additional medical or public health investment may help reduce the burden of AM.

METHODS

Taiwan's ASMRs per 100,000 for AM and other causes of death were calculated using data from the National Death Certificate Registry in five-year bins from 1971 to 2008. SEYLL rates per 100,000 were calculated annually from 1971 to 2008 using the same data source.

RESULTS

ASMR for almost all AM and other causes of death declined dramatically from 1971 to 2008 except for lung cancer (16.6% and 7.4% increase among men and women, respectively) and breast cancer (109.8% increase among women). In the same period, SEYLL due to lung cancer increased from 269.2 to 555.7 for men and 249.7 to 342.5 for women. For women, SEYLL due to breast cancer increased from 263.5 in 1971 to 659.3 in 2008. There were gender-specific differences in the reduction (or increase) in AM rates, with women showing larger rates of reduction or smaller rates of increase. Among men, AM fell by 65.9% from 1971-1975 to 2006-2008, and deaths from other causes increased by 15.6%. Among women, AM and deaths from other causes fell by 80.8% and 59.8% respectively. SEYLL decreased, respectively among males and females, from 23,147.3 and 24,081.1 in 1971 to 11,261.8 and 5,929.6 in 2008.

CONCLUSION

From 1971 to 2008, Taiwan experienced a dramatic reduction in most AM and corresponding SEYLL except for lung cancer (for both males and females) and breast cancer (for females). Additional effort should be devoted to public health measures to combat the rising prevalence of smoking in Taiwan, which may be responsible for the increasing AM from lung cancer. If AM in breast cancer continues unabated in the future, greater policy emphasis on the early detection and treatment of breast cancer may also be warranted.

Indoor air pollution and risk of lung cancer among Chinese female non-smokers

PURPOSE

To investigate indoor particulate matter (PM) level and various indoor air pollution exposure, and to examine their relationships with risk of lung cancer in an urban Chinese population, with a focus on non-smoking women.

METHODS

We conducted a case-control study in Taiyuan, China, consisting of 399 lung cancer cases and 466 controls, of which 164 cases and 218 controls were female non-smokers. Indoor PM concentrations, including PM(1), PM(2.5), PM(7), PM(10), and TSP, were measured using a particle mass monitor. Unconditional logistic regression models were used to calculate odds ratios (ORs) and 95 % confidence intervals after adjusting for age, education, annual income, and smoking.

RESULTS

Among non-smoking women, lung cancer was strongly associated with multiple sources of indoor air pollution 10 years ago, including heavy exposure to environmental tobacco smoke at work (aOR = 3.65), high frequency of cooking (aOR = 3.30), and solid fuel usage for cooking (aOR = 4.08) and heating (aOR(coal stove) = 2.00). Housing characteristics related to poor ventilation, including single-story, less window area, no separate kitchen, no ventilator, and rarely having windows open, are associated with lung cancer. Indoor medium PM(2.5) concentration was 68 μg/m(3), and PM(10) was 230 μg/m(3). PM levels in winter are strongly correlated with solid fuel usage for cooking, heating, and ventilators. PM(1) levels in cases are more than 3 times higher than that in controls. Every 10 μg/m(3) increase in PM(1) is associated with 45 % increased risk of lung cancer.

CONCLUSIONS

Indoor air pollution plays an important role in the development of lung cancer among non-smoking Chinese women.

Risk factors for primary lung cancer among never smokers by gender in a matched case-control study

OBJECTIVE

Lung cancers that occur in never smokers differ from those that occur in smokers. We performed an analysis of potential epidemiological risk factors for lung cancer among never smokers.

METHODS

In this hospital-based matched case-control study, all 1,540 matched case-control pairs were Han Chinese in Taiwan. The data on demographic characteristics, smoking habit, exposure to environmental tobacco smoke, medical history of lung diseases, family history of lung cancer, and female characteristics were collected from a structured questionnaire. A multiple conditional logistic regression was used to estimate odds ratios and 95 % confidence intervals after adjusting for possible confounders.

RESULTS

Overall, several epidemiological factors of lung cancer in never smokers were different between males and females. For the female population, subjects who were exposed to environmental tobacco smoke (OR = 1.39, 95 % CI = 1.17-1.67) with a history of pulmonary tuberculosis and with family history of lung cancer in first-degree relatives (OR = 2.44, 95 % CI = 1.79-3.32) had higher risk of lung cancer, while subjects with a history of hormone replacement therapy and using fume extractors for those who cooked were protective. For the male population, only subjects with family history of lung cancer in first-degree relatives (OR = 2.77, 95 % CI = 1.53-5.01) were significantly associated with risk of lung cancer.

CONCLUSION

This study provides insights about the epidemiological factors of lung cancer in never smokers, adding to existing evidence that family history of lung cancer and environmental tobacco smoke may moderate lung cancer risk.

Chemopreventive effects of NSAIDs as inhibitors of cyclooxygenase-2 and inducers of apoptosis in experimental lung carcinogenesis

Roles of cyclooxygenase (COX) enzyme and intrinsic pathway of apoptosis have been explored for the chemopreventive effects of non-steroidal anti-inflammatory drugs (NSAIDs) on 9,10-dimethyl benz(a)anthracene (DMBA)-induced lung cancer in rat model. 16 weeks after the administration of DMBA, morphological analysis revealed the occurrences of tumours and lesions, which were regressed considerably with the co-administration of indomethacin and etoricoxib, the two NSAIDs under investigation. DMBA group was marked by hyperplasia and dysplasia as observed by histological examination, and these features were corrected to a large extent by the two NSAIDs. Elevated levels of COX-2 were seen in the DMBA group, the enzyme responsible for prostaglandin synthesis during inflammation and cancer, whilst the expression of the constitutive isoform, COX-1, was equally expressed in all the groups. Apoptosis was quantified by studying the activities of apaf-1, caspase-9, and 3 by immunofluorescence and western blots. Their activities were found to diminish in the DMBA-treated animals as compared to the other groups. Fluorescent co-staining of the isolated broncho-alveolar lavage cells showed reduced number of apoptotic cells in the DMBA group, indicating decrease in apoptosis after carcinogen administration. The present results thus suggest that the mechanism of cancer chemoprevention of NSAIDs may include the suppression of COX-2 and the induction of apoptosis.

Cigarette smoking and p16INK4α gene promoter hypermethylation in non-small cell lung carcinoma patients: a meta-analysis

Background

Aberrant methylation of promoter DNA and transcriptional repression of specific tumor suppressor genes play an important role in carcinogenesis. Recently, many studies have investigated the association between cigarette smoking and p16^INK4α gene hypermethylation in lung cancer, but could not reach a unanimous conclusion.

Methods and Findings

Nineteen cross-sectional studies on the association between cigarette smoking and p16^INK4α methylation in surgically resected tumor tissues from non-small cell lung carcinoma (NSCLC) patients were identified in PubMed database until June 2011. For each study, a 2×2 cross-table was extracted. In total, 2,037 smoker and 765 nonsmoker patients were pooled with a fixed-effects model weighting for the inverse of the variance. Overall, the frequency of p16^INK4α hypermethylation was higher in NSCLC patients with smoking habits than that in non-smoking patients (OR = 2.25, 95% CI = 1.81–2.80). The positive association between cigarette smoking and p16^INK4α hypermethylation was similar in adenocarcinoma and squamous-cell carcinoma. In the stratified analyses, the association was stronger in Asian patients and in the studies with larger sample sizes.

Conclusion

Cigarette smoking is positively correlated to p16^INK4α gene hypermethylation in NSCLC patients.