In-home coal and wood use and lung cancer risk: a pooled analysis of the International Lung Cancer Consortium

Facing an un-met need in lung cancer screening: The never smokers

Lung cancer (LC) is the leading cause of cancer-related deaths worldwide and the second most common cancer in both men and women. In addition to smoking, other risk factors, such as environmental tobacco smoke, air pollution, biomass combustion, radon gas, occupational exposure, lung disease, family history of cancer, geographic variability, and genetic factors, play an essential role in developing LC. Current screening guidelines and eligibility criteria have limited efficacy in identifying LC cases (50 %), as most screening programs primarily target subjects with a smoking history as the leading risk factor. Implementing LC screening programs in people who have never smoked (PNS) can significantly impact cancer-specific survival and early disease detection. However, the available evidence regarding the feasibility and effectiveness of such programs is limited. Therefore, further research on LC screening in PNS is warranted to determine the necessary techniques for accurately identifying individuals who should be included in screening programs.

Age at lung cancer diagnosis in females versus males who never smoke by race and ethnicity

BACKGROUND

We characterized age at diagnosis and estimated sex differences for lung cancer and its histological subtypes among individuals who never smoke.

METHODS

We analyzed the distribution of age at lung cancer diagnosis in 33,793 individuals across 8 cohort studies and two national registries from East Asia, the United States (US) and the United Kingdom (UK). Student's t-tests were used to assess the study population differences (Δ years) in age at diagnosis comparing females and males who never smoke across subgroups defined by race/ethnicity, geographic location, and histological subtypes.

RESULTS

We found that among Chinese individuals diagnosed with lung cancer who never smoke, females were diagnosed with lung cancer younger than males in the Taiwan Cancer Registry (n = 29,832) (Δ years = -2.2 (95% confidence interval (CI):-2.5, -1.9), in Shanghai (n = 1049) (Δ years = -1.6 (95% CI:-2.9, -0.3), and in Sutter Health and Kaiser Permanente Hawai'i in the US (n = 82) (Δ years = -11.3 (95% CI: -17.7, -4.9). While there was a suggestion of similar patterns in African American and non-Hispanic White individuals. the estimated differences were not consistent across studies and were not statistically significant.

CONCLUSIONS

We found evidence of sex differences for age at lung cancer diagnosis among individuals who never smoke.

Global, regional, and national burden and trends of early-onset tracheal, bronchus, and lung cancer from 1990 to 2019

BACKGROUND

Tracheal, bronchus, and lung cancer (TBL) is one of the main cancer health problems worldwide, but data on the burden and trends of early-onset tracheal, bronchus, and lung cancer (EO-TBL) are sparse. The aim of the present study was to provide the latest and the most comprehensive burden estimates of the EO-TBL cancer from 1990 to 2019.

METHODS

Overall, we used data from the Global Burden of Disease (GBD) study in EO-TBL cancer from 1990 to 2019. Evaluation metrics included incidence, mortality, and disability-adjusted life years (DALYs). The joinpoint regression model was used to analyze the temporal trends. Decomposition analysis was employed to analyze the driving factors for EO-TBL cancer burden alterations. Bayesian age-period-cohort (BAPC) analysis was used to estimate trends in the next 20 years.

RESULTS

The global age-standardized incidence rate (ASIR), age-standardized mortality rate (ASMR), and age-standardized DALYs rate (ASDR) for EO-TBL cancer decreased significantly from 3.95 (95% uncertainty interval [UI]: 3.70-4.24), 3.41 (95% UI: 3.19-3.67), 158.68 (95% UI: 148.04-170.92) in 1990 to 2.82 (95% UI: 2.54-3.09), 2.28 (95% UI: 2.07-2.49), 106.47 (95% UI: 96.83-116.51) in 2019 with average annual percent change (AAPC) of -1.14% (95% confidence interval [CI]: -1.32 to -0.95), -1.37% (95% CI: -1.55 to -1.18), and - 1.35% (95% CI: -1.54 to -1.15) separately. The high and high-middle sociodemographic index (SDI) region had a higher burden of EO-TBL cancer but demonstrated a downward trend. The most prominent and significant upward trends were Southeast and South Asia, Africa, and women in the low SDI and low-middle SDI quintiles. At the regional and national level, there were significant positive correlations between ASDR, ASIR, ASMR, and SDI. Decomposition analysis showed that population growth and aging have driven the increase in the number of incidence, mortality, and DALYs in the global population, especially among the middle SDI quintile and the East Asia region. The BAPC results showed that ASDR, ASIR, and ASMR in women would increase but the male population remained relatively flat over the next 20 years.

CONCLUSIONS

Although global efforts have been the most successful and effective in reducing the burden of EO-TBL cancer over the past three decades, there was strong regional and gender heterogeneity. EO-TBL cancer need more medical attention in the lower SDI quintiles and in the female population.

A population-based study of 15,000 people on Knowledge and awareness of lung cancer symptoms and risk factors in Saudi Arabia

Background

Lung cancer is currently the most fatal form of cancer worldwide, ranking as the fourth most prevalent type in Saudi Arabia, particularly among males. This trend is expected to increase with growing population, lifestyle changes, and aging population. Understanding the awareness of the Saudi population regarding the risk factors and symptoms of lung cancer is necessary to attenuate the predicted increase in cases.

Method

A cross-sectional, population-based survey was performed using a previously validated questionnaire (Lung CAM). Multiple linear regression analysis was used to assess variables associated with deficiency in knowledge and awareness of risk factors and symptoms of lung cancer.

Results

Majority of the 15,099 respondents were male (65%), aged between 18 and 30 years (53%), 50% of which were educated up to a bachelor's degree level. Overall awareness of lung cancer signs and symptoms was 53%, with painful cough and coughing up blood being the best-known symptoms. Conversely, persistent shoulder pain (44%) and clubbing fingers (47%) were the least known lung cancer symptoms. Also, 60% of the respondents showed low confidence in identifying the signs and symptoms of lung cancer. The overall awareness of the risk factors for lung cancer development was 74%, with first-hand (74%) and second-hand (68%) smoking being the most known risk factors. However, only ≤ 62% know the other non-smoking risk factors. Awareness of the risk factors and symptoms of lung cancer depended on age, gender, education, marital and employment status (p < 0.001).

Conclusion

Public awareness of the risk factors and symptoms of lung cancer in Saudi Arabia is inadequate and heavily dependent on education and socio-economic status. Awareness can be improved through campaigns to raise awareness about other lesser-known lung cancer risk factors and symptoms.

Household air pollution and risk of incident lung cancer in urban China: A prospective cohort study

Household air pollution (HAP) is associated with the development of lung cancer, yet few studies investigated the exposure patterns and joint associations with tobacco smoking. In our study, we included 224 189 urban participants from China Kadoorie Biobank (CKB), 3288 of which diagnosed with lung cancer during the follow-up. Exposure to four HAP sources (solid fuels for cooking/heating/stove and environmental tobacco smoke exposure) was assessed at baseline. Distinct HAP patterns and their associations with lung cancer were examined through latent class analysis (LCA) and multivariable Cox regression. A total of 76.1% of the participants reported regular cooking and 52.2% reported winter heating, of which 9% and 24.7% used solid fuels, respectively. Solid fuel heating increased lung cancer risk (Hazards ratio [HR]: 1.25, 95% confidence interval [CI]: 1.08-1.46). LCA identified three HAP patterns; the "clean fuel cooking and solid fuel heating" pattern significantly increased lung cancer risk (HR: 1.25, 95% CI: 1.10-1.41), compared to low HAP pattern. An additive interaction was observed between heavy smoking and "clean fuel cooking and solid fuel heating" (relative excess risk [RERI]: 1.32, 95% CI: 0.29-2.47, attributable proportion [AP]: 0.23, 95% CI: 0.06-0.36). Cases resulting from solid fuel account for ~4% of total cases (population attribute fraction [PAF]overall : 4.31%, 95% CI: 2.16%-6.47%, PAFever smokers : 4.38%, 95% CI: 1.54%-7.23%). Our results suggest that in urban China, solid fuel heating increased the risk of lung cancer, particularly among heavy smokers. The whole population could benefit from cleaner indoor air quality by reducing using solid fuels, especially smokers.

The global burden of lung cancer: current status and future trends

Lung cancer is the leading cause of cancer-related death worldwide. However, lung cancer incidence and mortality rates differ substantially across the world, reflecting varying patterns of tobacco smoking, exposure to environmental risk factors and genetics. Tobacco smoking is the leading risk factor for lung cancer. Lung cancer incidence largely reflects trends in smoking patterns, which generally vary by sex and economic development. For this reason, tobacco control campaigns are a central part of global strategies designed to reduce lung cancer mortality. Environmental and occupational lung cancer risk factors, such as unprocessed biomass fuels, asbestos, arsenic and radon, can also contribute to lung cancer incidence in certain parts of the world. Over the past decade, large-cohort clinical studies have established that low-dose CT screening reduces lung cancer mortality, largely owing to increased diagnosis and treatment at earlier disease stages. These data have led to recommendations that individuals with a high risk of lung cancer undergo screening in several economically developed countries and increased implementation of screening worldwide. In this Review, we provide an overview of the global epidemiology of lung cancer. Lung cancer risk factors and global risk reduction efforts are also discussed. Finally, we summarize lung cancer screening policies and their implementation worldwide.

Narrative review: respiratory tract microbiome and never smoking lung cancer

Background and Objective

The lung microbiome was previously thought to be a sterile environment where only gaseous exchange takes place, but recent studies have shown the presence of microbiota in the lung. This review investigates the current literature on the effects of an environmental driven dysbiosis on the healthy oral and respiratory microbiome and its relationship to lung cancer risk in never-smokers.

Methods

An online electronic search was performed on PubMed of all English-language literature using combinations of the following keywords: "lung cancer", "dysbiosis", "non-smokers", "oral microbiome", and "respiratory microbiome". All population-based studies reporting results on oral and/or respiratory microbiome in adults were considered for our narrative review.

Key Content and Findings

Metagenomic analyses have been performed on isolated samples from healthy participants and compared to samples from those with lung cancer. Research shows that a decrease in alpha diversity of microbes in the oral microbiome is associated with increased risk of lung cancer, along with differences in beta diversity in the sputum of lung cancer cases and healthy controls. Further, several studies have observed that significant changes in the abundance of genera such as increased abundance of Lactobacillales, Bacilli, and Firmicutes associated with an increased lung cancer risk among participants with exposure to certain household solid fuels.

Conclusions

These findings suggest potential carcinogenic processes such as increased inflammation associated with changes in flora. Additionally, studies showed that increase in certain taxa such as Bacteroides and Spirochetes might have a protective effect on lung cancer risk. The review also provides insight into how understanding the microbial changes can be beneficial for lung cancer treatment and disease-free survival. Larger studies in different populations need to be performed to strengthen the current associations between microbial diversity and lung cancer risk.

Indoor wood-burning from stoves and fireplaces and incident lung cancer among Sister Study participants

BACKGROUND AND AIM

Epidemiological studies conducted mostly in low- and middle-income countries have found a positive association between household combustion of wood and lung cancer. However, most studies have been retrospective, and few have been conducted in the United States where indoor wood-burning usage patterns differ. We examined the association of exposure to indoor wood smoke from fireplaces and stoves with incident lung cancer in a U.S.-wide cohort of women.

METHODS

We included 50,226 women without prior lung cancer participating in the U.S.-based prospective Sister Study. At enrollment (2003-2009), women reported frequency of use of wood-burning stoves and/or fireplaces in their longest-lived adult residence. Cox regression was used to estimate adjusted hazard ratios (HRadj) and 95 % confidence intervals (CI) for the association between indoor wood-burning fireplace/stove use and incident lung cancer. Lung cancer was self-reported and confirmed with medical records.

RESULTS

During an average 11.3 years of follow-up, 347 medically confirmed lung cancer cases accrued. Overall, 62.3 % of the study population reported the presence of an indoor wood-burning fireplace/stove at their longest-lived adult residence and 20.6 % reported annual usage of ≥30 days/year. Compared to those without a wood-burning fireplace/stove, women who used their wood-burning fireplace/stove ≥30 days/year had an elevated rate of lung cancer (HRadj = 1.68; 95 % CI = 1.27, 2.20). In never smokers, positive associations were seen for use 1-29 days/year (HRadj = 1.64; 95 % CI = 0.87, 3.10) and ≥30 days/year (HRadj = 1.99; 95 % CI = 1.02, 3.89). Associations were also elevated across all income groups, in Northeastern, Western or Midwestern U.S. regions, and among those who lived in urban or rural/small town settings.

CONCLUSIONS

Our prospective analysis of a cohort of U.S. women found that increasing frequency of wood-burning indoor fireplace/stove usage was associated with incident lung cancer, even among never smokers.

How Does Environmental and Occupational Exposure Contribute to Carcinogenesis in Genitourinary and Lung Cancers?

Environmental and occupational exposures have been associated with an increased risk of different types of cancers, although the exact mechanisms of higher carcinogenesis risk are not always well understood. Lung cancer is the leading cause of global cancer mortality, and, also, genitourinary neoplasms are among the main causes of cancer-related deaths in Western countries. The purpose of this review is to describe the main environmental and occupational factors that increase the risk of developing lung and genitourinary cancers and to investigate carcinogenesis mechanisms that link these agents to cancer onset. Further objectives are to identify methods for the prevention or the early detection of carcinogenic agents and, therefore, to reduce the risk of developing these cancers or to detect them at earlier stages.

Incidence of Concomitant Neoplastic Diseases, Tumor Characteristics, and the Survival of Patients with Lung Adenocarcinoma or Squamous Cell Lung Carcinoma in Tobacco Smokers and Non-Smokers-10-Year Retrospective Single-Centre Cohort Study

Changes in smoking trends and changes in lifestyle, together with worldwide data regarding the incidence of lung cancer in the group of patients with no previous history of smoking, leads to consideration of the differences in the course of the disease, the time of cancer diagnosis, the survival rate, and the occurrence of comorbidities in this group of patients. This study aimed to determine the occurrence of non-smokers among patients undergoing anatomical resection of the lung tissue due to lung carcinoma and to investigate the differences between the course of lung cancer, survival, and the comorbidities in the groups of patients with lung cancer depending on the history of tobacco smoking. The study included a cohort of 923 patients who underwent radical anatomical resection of the lung tissue with lung primary adenocarcinoma or squamous cell carcinoma. The Chi2 Pearson's test, the t-test, the Mann-Whitney U test, the Kaplan-Meier method, the Log-rank test with Mantel correction, and the Cox proportional hazard model were used for data analysis. We observed a significantly higher mean age of smoking patients compared to the mean age of non-smoking patients. The coexistence of former neoplastic diseases was significantly more frequent in the group of non-smokers compared to the group of smoking patients. We did not observe differences depending on smoking status in the tumor stage, grade, vascular and pleural involvement status in the diagnostic reports. We did not observe differences in the survival between smokers vs. non-smokers, however, we revealed better survival in the non-smoker women group compared to the non-smoker men group. In conclusion, 22.11% of the patients undergoing radical anatomical resection of the lung tissue due to lung cancers were non-smokers. More research on survival depending on genetic differences and postoperative treatment between smokers and non-smokers is necessary.

Lung Effects of Household Air Pollution

Biomass fuel smoke, secondhand smoke, and oxides of nitrogen are common causes of household air pollution (HAP). Almost 2.4 billion people worldwide use solid fuels for cooking and heating, mostly in low- and middle-income countries. Wood combustion for household heating is also common in many areas of high-income countries, and minorities are particularly vulnerable. HAP in low- and middle-income countries is associated with asthma, acute respiratory tract infections in adults and children, chronic obstructive pulmonary disease, lung cancer, tuberculosis, and respiratory mortality. Although wood smoke exposure levels in high-income countries are typically lower than in lower-income countries, it is similarly associated with accelerated lung function decline, higher prevalence of airflow obstruction and chronic bronchitis, and higher all-cause and respiratory cause-specific mortality. Household air cleaners with high-efficiency particle filters have mixed effects on asthma and chronic obstructive pulmonary disease outcomes. Biomass fuel interventions in low-income countries include adding chimneys to cookstoves, improving biomass fuel combustion stoves, and switching fuel to liquid petroleum gas. Still, the impact on health outcomes is inconsistent. In high-income countries, strategies for reducing biomass fuel-related HAP are centered on community-level woodstove changeout programs, although the results are again inconsistent. In addition, initiatives to encourage home smoking bans have mixed success in households with children. Environmental solutions to reduce HAP have varying success in reducing pollutants and health problems. Improved understanding of indoor air quality factors and actions that prevent degradation or improve polluted indoor air may lead to enhanced environmental health policies, but health outcomes must be rigorously examined.

Wood smoke exposure affects lung aging, quality of life, and all-cause mortality in New Mexican smokers

Background

The role of wood smoke (WS) exposure in the etiology of chronic obstructive pulmonary disease (COPD), lung cancer (LC), and mortality remains elusive in adults from countries with low ambient levels of combustion-emitted particulate matter. This study aims to delineate the impact of WS exposure on lung health and mortality in adults age 40 and older who ever smoked.

Methods

We assessed health impact of self-reported “ever WS exposure for over a year” in the Lovelace Smokers Cohort using both objective measures (i.e., lung function decline, LC incidence, and deaths) and two health related quality-of-life questionnaires (i.e., lung disease-specific St. George's Respiratory Questionnaire [SGRQ] and the generic 36-item short-form health survey).

Results

Compared to subjects without WS exposure, subjects with WS exposure had a more rapid decline of FEV1 (− 4.3 ml/s, P = 0.025) and FEV1/FVC ratio (− 0.093%, P = 0.015), but not of FVC (− 2.4 ml, P = 0.30). Age modified the impacts of WS exposure on lung function decline. WS exposure impaired all health domains with the increase in SGRQ scores exceeding the minimal clinically important difference. WS exposure increased hazard for incidence of LC and death of all-cause, cardiopulmonary diseases, and cancers by > 50% and shortened the lifespan by 3.5 year. We found no evidence for differential misclassification or confounding from socioeconomic status for the health effects of WS exposure.

Conclusions

We identified epidemiological evidence supporting WS exposure as an independent etiological factor for the development of COPD through accelerating lung function decline in an obstructive pattern. Time-to-event analyses of LC incidence and cancer-specific mortality provide human evidence supporting the carcinogenicity of WS exposure.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02162-y.

Gender disparities in incidence and projections of lung cancer in China and the United States from 1978 to 2032: an age-period-cohort analysis

PURPOSE

Lung cancer incidences tend to be higher among males than females in both China and the United States, yet secular incidence patterns are different due to distinct population and environmental exposures. We examined long-term and future trends of lung cancer incidence, as well as the associations of age, period, and cohort effects with gender disparities.

METHODS

Using data from the Cancer Incidence in Five Continents from 1978 to 2012, we calculated age-standardized, age-specific incidence, and male-to-female incidence rate ratios (IRR), and conducted an age-period-cohort analysis. The average annual percentage change (AAPC) of the trends was obtained by Joinpoint Regression. Bayesian age-period-cohort analysis was also conducted to project incidences to 2032.

RESULTS

In China, age-standardized incidence revealed a decreasing trend among males, but showed increasing trends among the younger age groups (30-54 years) in females. Age-standardized incidence rates of males decreased but remained stable among females from 1972 to 2012 in the United States. Male-to-female incidence rate ratios narrowed in both countries and reversed among younger birth cohorts in the United States. Gender disparities are expected to continue to diminish in both countries, and incidence among females appears to exceed that of males in the United States by around 2023-2027.

CONCLUSION

Gender disparities in lung cancer incidence persist and will continue into the future in both countries, but our findings suggested that smoking may play different roles in gender disparities in lung cancer incidence between the two countries. Further population-based epidemiological studies among females in China are imperative.

Unique characteristics of G719X and S768I compound double mutations of epidermal growth factor receptor (EGFR) gene in lung cancer of coal-producing areas of East Yunnan in Southwestern China

Background

The principal objective of this project was to investigate the Epidermal Growth Factor Receptor (EGFR) gene mutation characteristics of lung cancer patients, which can provide a molecular basis for explaining the clinicopathological features, epidemiology and use of targeted therapy in lung cancer patients in the coal-producing areas of East Yunnan.

Methodology

We collected 864 pathologically confirmed lung cancer patients’ specimens in First People’s Hospital of Qujing City of Yunnan Province from September 2016 to September 2021. We thereafter employed Next Generation Sequencing (NGS) technology to detect all exons present in the EGFR gene.

Results

The overall mutation frequency of the EGFR gene was 47.22%. The frequency of EGFR gene mutations in the tissue, plasma, and cytology samples were found to be 53.40%, 23.33%, and 62.50%, respectively. Univariate analysis indicated that the coal-producing areas and Fuyuan county origin were significantly associated with relatively low EGFR gene mutation frequency. Female, non-smoking history, adenocarcinoma, non-brain metastasis, and tissue specimens were found to be related to high EGFR gene mutation frequency. Multivariate logistic regression analysis suggested the lung cancer patients in the central area of Qujing City, stage Ia, non-coal-producing areas, non-Fuyuan origin, and non-Xuanwei origin were more likely to develop EGFR gene mutations. The most common mutations were L858R point mutation (33.09%) and exon 19 deletion (19-del) (21.32%). Interestingly, the mutation frequency of G719X (p = 0.001) and G719X + S768I (p = 0.000) in the coal-producing areas were noted to be more significant than those in non-coal-producing regions.

Conclusion

This findings of this study might be important in establishing the correlation between routine using NGS for EGFR gene mutation diagnosis and clinical practice in the lung cancer patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41021-022-00248-z.

Hypothesized Explanations for the Observed Lung Cancer Survival Benefit Among Hispanics/Latinos in the United States

Hispanic/Latino ethnicity is associated with improved survival from non-small cell lung cancer compared to that for non-Hispanic Whites even though Hispanics/Latinos are more likely to potentially have inferior access-to-care and experience greater health disparities. To this end, we conducted a literature review to identify possible explanations for this survival benefit, including the role of chronic obstructive pulmonary disease and cardiovascular diseases, genetic variation, cultural influences, and immigration factors. Overall, intermittent smoking patterns, genetic variation, co-morbidities, and cultural influences were all factors likely to partially explain this survival benefit. On the other hand, immigration factors, acculturation, and access-to-care were less likely to support the survival advantage. Future research should analyze relevant Hispanic/Latino subgroups (e.g., Mexican, Puerto Rican, Cuban, Dominican, Central American, South American) and specifically focus on the relationship between Hispanic/Latino ethnicity and different lung cancer subtypes. If the Hispanic/Latino mortality benefit observed in lung cancer truly exists, a better understanding of the underlying mechanism(s) may help extend these benefits to other ethnic and racial groups.

Characteristics, Source Contributions, and Source-Specific Health Risks of PM2.5-Bound Polycyclic Aromatic Hydrocarbons for Senior Citizens during the Heating Season in Tianjin, China

Polycyclic aromatic hydrocarbons (PAHs) have carcinogenic impacts on human health. However, limited studies are available on the characteristics, sources, and source-specific health risks of PM2.5-bound PAHs based on personal exposure data, and comparisons of the contributions of indoor and outdoor sources are also lacking. We recruited 101 senior citizens in the winter of 2011 for personal PM2.5 sample collection. Fourteen PAHs were analyzed, potential sources were apportioned using positive matrix factorization (PMF), and inhalational carcinogenic risks of each source were estimated. Six emission sources were identified, including coal combustion, gasoline emission, diesel emission, biomass burning, cooking, and environmental tobacco smoking (ETS). The contribution to carcinogenic risk of each source occurred in the following sequence: biomass burning > diesel emission > gasoline emission > ETS > coal combustion > cooking. Moreover, the contributions of biomass burning, diesel emission, ETS, and indoor sources (sum of cooking and ETS) to PAH-induced carcinogenic risk were higher than those to the PAH mass concentration, suggesting severe carcinogenic risk per unit contribution. This study revealed the contribution of indoor and outdoor sources to mass concentration and carcinogenic risk of PM2.5-bound PAHs, which could act as a guide to mitigate the exposure level and risk of PM2.5-bound PAHs.

The evolving landscape of sex-based differences in lung cancer: a distinct disease in women

In stark contrast to a few decades ago when lung cancer was predominantly a disease of men who smoke, incidence rates of lung cancer in women are now comparable to or higher than those in men and are rising alarmingly in many parts of the world. Women face a unique set of risk factors for lung cancer compared to men. These include exogenous exposures including radon, prior radiation, and fumes from indoor cooking materials such as coal, in addition to endogenous exposures such as oestrogen and distinct genetic polymorphisms. Current screening guidelines only address tobacco use and likely underrepresent lung cancer risk in women. Women were also not well represented in some of the landmark prospective studies that led to the development of current screening guidelines. Women diagnosed with lung cancer have a clear mortality benefit compared to men even when other clinical and demographic characteristics are accounted for. However, there may be sex-based differences in outcomes and side effects of systemic therapy, particularly with chemotherapy and immunotherapy. Ongoing research is needed to better investigate these differences to address the rapidly changing demographics of lung cancer worldwide.

Sex-based differences in lung cancer span the care continuum. This suggests lung cancer may increasingly be viewed as a distinct disease in women, with implications for screening and treatment. Lung cancer research should capture these sex-based differences.https://bit.ly/2WfhaB4

A systematic review on solid fuel combustion exposure and respiratory health in adults in Europe, USA, Canada, Australia and New Zealand

Epidemiological studies performed in low- and middle-income countries have shown a positive association between solid fuel burning exposure and adverse health effects, including respiratory effects in adults. However, the evidence is less clear in other countries. We performed a systematic review of epidemiological studies conducted in Europe, North America (Canada and USA only), Australia and New Zealand on the association between outdoor and indoor exposure to solid fuel (biomass and coal) combustion and respiratory outcomes in adults. We identified 34 articles. The epidemiological evidence is still limited. Positive associations were found between indoor coal, wood and combined solid fuel combustion exposure and lung cancer risk, although based on a limited number of studies. A significant association was found between indoor solid fuel exposure and COPD risk. Inconsistent results were found considering indoor coal, wood and mixed solid fuel burning exposure and other respiratory outcomes (i.e. lower respiratory infections, upper respiratory infections and other upper respiratory tract diseases, asthma and respiratory symptoms). Inconsistent results were found considering the relationship between the exposure to outdoor wood burning exposure and overall respiratory mortality, asthma, COPD and respiratory symptoms in adults. The available epidemiological evidence between outdoor exposure to residential coal burning and respiratory outcomes suggests an increased risk of adverse respiratory effects. The studies considering the impact of the introduction of measures in order to reduce solid fuel burning on air quality and health showed an improvement in air quality resulting in a reduction of adverse respiratory effects. The identified epidemiological studies have several limitations. Additional and better conducted epidemiological studies are needed to establish whether exposure occurring indoors and outdoors to solid fuel combustion pollutants is associated with adverse respiratory outcomes in adults.

A concise review towards defining the exposome of oesophageal cancer in sub-Saharan Africa

CONTEXT

Oesophageal cancer (EC) is among the common causes of illness and death among all cancers worldwide. Advanced EC has a poor prognosis, with worse outcomes observed in low-income settings. Oesophageal squamous cell carcinoma (ESCC) is the most common EC histology reported globally, with the highest ESCC incidence rates in the 'Asian Belt' and the African EC corridor. While the aetiology of ESCC is well-documented in the 'Asian belt', data for the African EC corridor and the entirety of sub-Saharan Africa (SSA) are fewer.

OBJECTIVE

To help address gaps in ESCC aetiology in SSA, we critically evaluated evidence of lifestyle, environmental, and epigenetic factors associated with ESCC risk and discussed prospects of defining ESCC exposome.

DATA INCLUSION

Unlimited English and non-English articles search were made on PubMed Central and Web of Science databases from January 1970 to August 2021. In total, we retrieved 999 articles and considered meta-analyses, case-control, and cohort studies. The quality of individual studies was assessed using the Newcastle-Ottawa scale.

DATA EXTRACTION

Details extracted include the year of publication, country of origin, sample size, comparators, outcomes, study subjects, and designs.

DATA ANALYSIS

Together, we assessed 13 case-control studies and two meta-analyses for the effect of lifestyle or environmental exposures on ESCC risk. Again, we evaluated seven case-control studies and one meta-analysis regarding the role of epigenetics in ESCC tumorigenesis.

RESULTS

In general, evidence of ESCC aetiology points to essential contributions of alcohol, tobacco, hot beverages, biomass fuel, and poor oral health/hygiene, although more precise risk characterisation remains necessary.

CONCLUSION

We conclude that ESCC in SSA is a multifactorial disease initiated by several external exposures that may induce aberrant epigenetic changes. The expanding aetiological research in this domain will be enhanced by evidence synthesis from classical and molecular epidemiological studies spanning the external and internal exposome.

Case-control study about magnitude of exposure to wood smoke and risk of developing lung cancer

INTRODUCTION

Exposure to biomass combustion products, particularly firewood, has been considered as a potential carcinogen for developing lung cancer. In this regard, current evidence is widely heterogeneous; besides, in most studies, wood smoke exposure is not appropriately quantified, which further complicates the analysis of wood smoke as a potential carcinogen. The aim of the present study was to estimate the risk of developing lung cancer according to the degree of exposure to wood smoke in patients who use firewood for cooking.

MATERIAL AND METHODS

We performed a case-control study that included 482 patients with lung cancer (cases) and 592 hospital controls. Exposure to wood smoke was evaluated as a dichotomous variable (i.e. yes or no); in patients with prior wood smoke exposure, an index of exposure in hours per year was calculated (WSEI). Using bivariate and multivariate logistic regression analyses, the odds ratio (OR) between wood smoke exposure and lung cancer were calculated.

RESULTS

The ORs for developing lung cancer (raw and adjusted) for a WSEI > 100 h/year were OR 1.55 [95% confidence interval (CI), 1.06-2.26) and OR 2.26 (95% CI, 1.50-3.40), respectively; the ORs (raw and adjusted) for WSEI >300 h/year were OR 1.76 (95% CI, 1.06-2.91) and OR 3.19 (95% CI, 1.83-5.55), respectively.

CONCLUSIONS

Exposure to wood smoke is a risk factor for lung cancer; furthermore, this effect maintains a dose-response relationship which has a multiplicative effect with smoking.

Health impacts of indoor air pollution from household solid fuel on children and women

The inefficient and incomplete combustion of solid fuel (SF) is associated with high levels of indoor air pollutants leading to 3.55 million deaths annually. The risk is higher in women and children, due to their higher exposure duration and unique physical properties. The current article aims to provide a critical overview regarding the use of solid fuel, its associated pollutants, their toxicity mechanisms and, most importantly the associated health impacts, especially in women and children. Pollutants associated with SF mostly include polycyclic aromatic hydrocarbons, particulate matter, nitrous oxide, carbon monoxide and sulfur dioxide, and their concentrations are two- to threefold higher in indoor environments. These pollutants can lead to a variety of health risks by inducing different toxicity mechanisms, such as oxidative stress, DNA methylation, and gene activation. Exposed children have an increased prevalence of low birth weight, acute lower respiratory tract infections, anemia and premature mortality. On the other hand, lung cancer, chronic obstructive pulmonary disease and cardiovascular diseases are the major causes of disability and premature death in women. Indoor air pollution resulting from SF combustion is a major public health threat globally. To reduce the risks, it is important to identify future research gaps and implement effective interventions and policies.

Indoor solid fuel use and incident arthritis among middle-aged and older adults in rural China: A nationwide population-based cohort study

BACKGROUND

Many households in developing countries, including China, rely on the traditional use of solid fuels for cooking and heating. Arthritis is highly prevalent in middle-aged and older adults and is a major cause of disability. However, evidence linking indoor solid fuel use with arthritis is scarce in this age group (≥45 years) in developing countries.

OBJECTIVES

To investigate whether exposure to indoor solid fuel for cooking and heating is associated with arthritis in middle-aged and older adults in rural China.

METHODS

Data for the present study were extracted from the China Health and Retirement Longitudinal Study (CHARLS), a longitudinal national prospective study of adults aged 45 years and older enrolled in 2010 and followed up through 2015. We included 7807 rural participants without arthritis at baseline, of whom 1548 living in a central heating area in winter were included in the heating analysis (taking the Qinling-Huaihe line as the heating boundary). Cox proportional hazards models were used to examine the association between indoor solid fuel use and arthritis, controlling for age, sex, education, marital status, smoking status, drinking status, self-reported socioeconomic status, BMI, sleep time, napping time, independent cooking, hypertension, diabetes, dyslipidemia, heart problems and stroke. We also investigated the effect of switching primary fuels and using solid fuels for both cooking and heating on arthritis risk.

RESULTS

The mean (SD) age of the study participants was 59.2 (10.0) years old, and 48.0% of participants were women. A total of 64.8% and 63.0% of the participants reported primarily using solid fuel for cooking and heating, respectively. Arthritis incidence rates were lower among clean fuel users than solid fuel users. Compared to those using clean fuels, cooking and heating solid fuel users had a higher risk of arthritis, with hazard ratios (HRs) of 1.22 (95% confidence interval (CI): 1.01, 1.49) and 1.76 (95% CI: 1.07, 2.89), respectively. Switching from clean fuels to solid fuels for heating (HR: 3.28, 95% CI: 1.21, 7.91) and using solid fuels for both cooking and heating (HR, 1.71, 95% CI, 1.01-2.79) increased the risk of arthritis.

CONCLUSIONS

Long-term solid fuel use for indoor cooking and heating is associated with an increased risk of arthritis events among adults aged 45 years and older in rural China. The potential benefits of reducing indoor solid fuel use in groups at high risk for arthritis merit further exploration.

Tracing Lung Cancer Risk Factors Through Mutational Signatures in Never-Smokers

Epidemiologic studies often rely on questionnaire data, exposure measurement tools, and/or biomarkers to identify risk factors and the underlying carcinogenic processes. An emerging and promising complementary approach to investigate cancer etiology is the study of somatic "mutational signatures" that endogenous and exogenous processes imprint on the cellular genome. These signatures can be identified from a complex web of somatic mutations thanks to advances in DNA sequencing technology and analytical algorithms. This approach is at the core of the Sherlock-Lung study (2018-ongoing), a retrospective case-only study of over 2,000 lung cancers in never-smokers (LCINS), using different patterns of mutations observed within LCINS tumors to trace back possible exposures or endogenous processes. Whole genome and transcriptome sequencing, genome-wide methylation, microbiome, and other analyses are integrated with data from histological and radiological imaging, lifestyle, demographic characteristics, environmental and occupational exposures, and medical records to classify LCINS into subtypes that could reveal distinct risk factors. To date, we have received samples and data from 1,370 LCINS cases from 17 study sites worldwide and whole-genome sequencing has been completed on 1,257 samples. Here, we present the Sherlock-Lung study design and analytical strategy, also illustrating some empirical challenges and the potential for this approach in future epidemiologic studies.

Sub-multiplicative interaction between polygenic risk score and household coal use in relation to lung adenocarcinoma among never-smoking women in Asia

We previously identified 10 lung adenocarcinoma susceptibility loci in a genome-wide association study (GWAS) conducted in the Female Lung Cancer Consortium in Asia (FLCCA), the largest genomic study of lung cancer among never-smoking women to date. Furthermore, household coal use for cooking and heating has been linked to lung cancer in Asia, especially in Xuanwei, China. We investigated the potential interaction between genetic susceptibility and coal use in FLCCA. We analyzed GWAS-data from Taiwan, Shanghai, and Shenyang (1472 cases; 1497 controls), as well as a separate study conducted in Xuanwei (152 cases; 522 controls) for additional analyses. We summarized genetic susceptibility using a polygenic risk score (PRS), which was the weighted sum of the risk-alleles from the 10 previously identified loci. We estimated associations between a PRS, coal use (ever/never), and lung adenocarcinoma with multivariable logistic regression models, and evaluated potential gene-environment interactions using likelihood ratio tests. There was a strong association between continuous PRS and lung adenocarcinoma among never coal users (Odds Ratio (OR) = 1.69 (95% Confidence Interval (CI) = 1.53, 1.87), p=1 × 10-26). This effect was attenuated among ever coal users (OR = 1.24 (95% CI: 1.03, 1.50), p = 0.02, p-interaction = 6 × 10-3). We observed similar attenuation among coal users from Xuanwei. Our study provides evidence that genetic susceptibility to lung adenocarcinoma among never-smoking Asian women is weaker among coal users. These results suggest that lung cancer pathogenesis may differ, at least partially, depending on exposure to coal combustion products. Notably, these novel findings are among the few instances of sub-multiplicative gene-environment interactions in the cancer literature.

Women with COPD from biomass smoke have reduced serum levels of biomarkers of angiogenesis and cancer, with EGFR predominating, compared to women with COPD from smoking

The main causes of COPD are smoking (COPD-TS) and exposure to biomass smoke (COPD-BS), considered as different phenotypes. The association of COPD-TS with lung cancer (LC) is well established, but not in COPD-BS. Thus, we studied the serum concentration of cytokines that participate in inflammation, angiogenesis, and tumor progression, used frequently as LC biomarkers, in women with COPD-BS compared with COPD-TS (n = 70). Clinical and physiological characteristics and the serum concentration (multiplex immunoassay) of 16 cytokines were evaluated. The analysis revealed that women with COPD-BS were shorter and older, and had lower concentrations of 12 serum cytokines: 6 proinflammatory and angiogenic IL-6Rα, PECAM-1, leptin, osteopontin, prolactin, and follistatin; and 6 that participate in angiogenesis and in tumor progression FGF-2, HGF, sVEGFR-2, sHER2/neu, sTIE-2, G-CSF, and SCF. Notably, there was a significant increase in sEGFR in women with COPD-BS compared to women with COPD-TS. PDGF-AA/BB and sTIE-2 did not change. These findings suggest that women with COPD-BS have markedly decreased proinflammatory, angiogenic, and tumor progression potential, compared to women with COPD-TS, with sEGFR as the predominant mediator, which might reflect a differential pattern of inflammation in women exposed to BS, favoring the development of chronic bronchitis.

Lung cancer incidence in young women vs. young men: A systematic analysis in 40 countries

Previous studies have reported converging lung cancer rates between sexes. We examine lung cancer incidence rates in young women vs. young men in 40 countries across five continents. Lung and bronchial cancer cases by 5-year age group (ages 30-64) and 5-year calendar period (1993-2012) were extracted from Cancer Incidence in Five Continents. Female-to-male incidence rate ratios (IRRs) and 95% confidence intervals (95%CIs) were calculated by age group and birth cohort. Among men, age-specific lung cancer incidence rates generally decreased in all countries, while in women the rates varied across countries with the trends in most countries stable or declining, albeit at a slower pace compared to those in men. As a result, the female-to-male IRRs increased among recent birth cohorts, with IRRs significantly greater than unity in Canada, Denmark, Germany, New Zealand, the Netherlands and the United States. For example, the IRRs in ages 45-49 year in the Netherlands increased from 0.7 (95% CI: 0.6-0.8) to 1.5 (95% CI: 1.4-1.7) in those born circa 1948 and 1963, respectively. Similar patterns, though nonsignificant, were found in 23 additional countries. These crossovers were largely driven by increasing adenocarcinoma incidence rates in women. For those countries with historical smoking data, smoking prevalence in women approached, but rarely exceeded, those of men. In conclusion, the emerging higher lung cancer incidence rates in young women compared to young men is widespread and not fully explained by sex differences in smoking patterns. Future studies are needed to identify reasons for the elevated incidence of lung cancer among young women.

Cardiovascular Effects of Indoor Air Pollution from Solid Fuel: Relevance to Sub-Saharan Africa

PURPOSE OF REVIEW

This research aims to summarize evidence on the cardiovascular effects of indoor air pollution (IAP) from solid fuel and identify areas for research and policy for low- and middle-income countries.

RECENT FINDINGS

IAP affects people from low socioeconomic status in Latin America, Asia, and Africa, who depend upon biomass as a fuel for cooking, heating, and lighting. In these settings, IAP disproportionately affects women, children, the elderly, and people with cardiopulmonary disease. The health effects of IAP include acute respiratory infections, chronic obstructive pulmonary disease, pneumoconiosis, cataract and blindness, pulmonary tuberculosis, adverse effects to pregnancy, cancer, and cardiovascular and cerebrovascular disease. New methods for assessing individual IAP exposure, exposing pathways of IAP-related cardiovascular disease, and performing qualitative research focusing on population preferences regarding strategies to reduce IAP exposure have been the most important developments in tackling the burden of IAP. Unfortunately, major disparities exist regarding research into the cardiovascular effects of IAP, with only few studies coming from sub-Saharan Africa, despite this region having the highest proportion of households using solid fuels. Premature cardiovascular deaths and disability can be averted in low-middle income countries by addressing biomass fuel usage by the most disadvantaged settings. While research is needed to uncover the mechanisms involved in cardiovascular outcomes linked to IAP, immediate action is needed to educate the most affected populations on IAP health hazards and to reduce their exposure to this environmental risk through promoting improved housing and better ventilation, as well as increasing access to affordable clean cooking energy.

Depression in the house: The effects of household air pollution from solid fuel use among the middle-aged and older population in China

BACKGROUND

Although the adverse health effects of ambient air pollution are well documented, evidence on the depression effects of household air pollution (HAP) are scarce.

OBJECTIVES

We investigated the effects of HAP exposure from the use of solid fuel on depression using a nationally representative dataset of middle-aged and older population in China.

METHODS

By employing the propensity score matching method, we first matched the type of household fuel based on background information, including demographic characteristics, lifestyles, health status, and household economic levels. Based on the matched data, we conducted OLS and logistic regressions with cluster standard error at community level to examine the effects of household solid fuel use on depression and adjusted for potential confounders. Heterogeneous effects for vulnerable population were also considered.

RESULTS

We found a significantly higher Center for Epidemiologic Studies Depression Scale (CES-D) score and depression risk among current household solid fuel users. After matching and adjusting for potential confounders, current solid fuel users had a higher CES-D score of 0.59 (95% confidence interval [CI]: 0.31, 0.89) than clean fuel users. The OR of depression risk were 1.26 (95% CI: 1.14, 1.41). Solid fuel users had the highest CES-D scores (β = 0.99, 95% CI: 0.62, 1.36) and depression risk (OR = 1.49, 95% CI: 1.30, 1.73) for over five years. These associations were generally higher in females, participants aged 65 years and older, with a BMI ≥ 25, with low education, with low household economic levels, and those suffer from chronic diseases, including diabetes, chronic lung diseases, and cardiovascular diseases.

CONCLUSIONS

Exposure to HAP from solid fuel combustion was linked with strong depression outcomes. Findings suggested a need to strengthen public health efforts, such as controlling the social, health, and economic costs of depression by taking the physical environment, including HAP exposure, into account.

Cancer-related mortality in Peru: Trends from 2003 to 2016

OBJECTIVES

In the last decade, Latin American (LA) countries, like Peru, have undergone an epidemiological transition that has changed the pattern of oncological cases. Given that Peru's oncological pattern could illustrate those of other LA countries, we aimed at determining trends and changes in cancer-related mortality by age and sex in Peru between 2003 and 2016.

METHODS AND RESULTS

A secondary data analysis using national deaths registries was conducted. Categories were created according to the 27 most frequent sites of presentation of cancer. We found that deaths attributed to cancer increased from 15.4% of all deaths in 2003 to 18.1% in 2016 (p<0.001). According to the cancer site, stomach cancer (19.1%) and lung cancer (11.5%) were the most frequent causes of death overall. In childhood (0 to 14 years), the two most frequent fatal cancers were leukemia (54.6% for boys and 53.5% for girls) and brain and nervous system tumors (19.4% for boys and 20.3% for girls). For teenagers and young male adults (15-49 years), stomach cancer (18.1%) and brain cancer (17.4%) were the leading causes of death; in their female counterparts, cervix uteri (20.0%) and breast cancer (16.1%) were the most mortal cancers. In adults (≥50 years), stomach (20.9% for men and 18.6% for women) and lung (12.7% for men and 10.4% for women) were the leading contributors to the burden of cancer deaths.

CONCLUSIONS

Between the years 2003 and 2016, almost one fifth of deaths were attributed to cancer in Peru. Absolute and relative number of deaths due to cancer has increased in this period for both men and women; however, standardized mortality rates due to cancer have declined.

Lung cancer in never smokers: The role of different risk factors other than tobacco smoking

Lung cancer (LC), the leading cause of cancer-related deaths worldwide, is a complex and highly heterogeneous disease. Additional to its biological complexity, LC patients are often confronted with a high degree of stigma, mostly from the association of the disease with tobacco. Nonetheless, a proportion of LC patients are never-smokers, a population which we are beginning to comprehensively explore. Several risk factors have been linked to LC in never-smokers. Studies have consistently shown that radon exposure and domestic fuel smoke increase LC risk. Additionally, infections such as Mycobacterium tuberculosis, and Human Papilloma Virus are also risk factors. Other less conclusive associations include inflammatory diseases such as asthma and sarcoidosis. Moreover, we are now aware that molecular characteristics of LC vary widely according to smoking history, with important therapeutic implications. This review comprehensively assesses the current knowledge in terms of risk factors and disease characteristics in the never-smoker lung cancer population.

Molecular Insights into Potential Contributions of Natural Polyphenols to Lung Cancer Treatment

Naturally occurring polyphenols are believed to have beneficial effects in the prevention and treatment of a myriad of disorders due to their anti-inflammatory, antioxidant, antineoplastic, cytotoxic, and immunomodulatory activities documented in a large body of literature. In the era of molecular medicine and targeted therapy, there is a growing interest in characterizing the molecular mechanisms by which polyphenol compounds interact with multiple protein targets and signaling pathways that regulate key cellular processes under both normal and pathological conditions. Numerous studies suggest that natural polyphenols have chemopreventive and/or chemotherapeutic properties against different types of cancer by acting through different molecular mechanisms. The present review summarizes recent preclinical studies on the applications of bioactive polyphenols in lung cancer therapy, with an emphasis on the molecular mechanisms that underlie the therapeutic effects of major polyphenols on lung cancer. We also discuss the potential of the polyphenol-based combination therapy as an attractive therapeutic strategy against lung cancer.

Chronic obstructive pulmonary disease (COPD) and lung cancer: common pathways for pathogenesis

Chronic obstructive pulmonary disease (COPD) and lung cancer comprise the leading causes of lung disease-related mortality worldwide. Exposure to tobacco smoke is a mutual aetiology underlying the two diseases, accounting for almost 90% of cases. There is accumulating evidence supporting the role of immune dysfunction, the lung microbiome, extracellular vesicles and underlying genetic susceptibility in the development of COPD and lung cancer. Further, epigenetic factors, involving DNA methylation and microRNA expression, have been implicated in both diseases. Chronic inflammation is a key feature of COPD and could be a potential driver of lung cancer development. Using next generation technologies, further studies investigating the genomics, epigenetics and gene-environment interaction in key molecular pathways will continue to elucidate the pathogenic mechanisms underlying the development of COPD and lung cancer, and contribute to the development of novel diagnostic and prognostic tools for early intervention and personalised therapeutic strategies.

Association between the risk of lung cancer and influenza: A population-based nested case-control study

BACKGROUND

Previous animal studies have shown that certain respiratory oncoviruses can lead to tumorigenesis, especially influenza virus. However, no clinical studies other than animal studies have been conducted to test this hypothesis.

OBJECTIVE

To investigate the association between influenza and the risk of lung cancer using the Taiwan Cancer Registry Database (TCRD) and Taiwan's National Health Insurance Research Database (NHIRD).

METHODS

We identified a study cohort consisting of patients aged 40 years or above who were enrolled in the NHIRD between 1 January 2012 and 31 December 2014. Among them, we identified patients with lung cancer (cases) and their matched controls (matched by age, sex, and disease risk score (DRS) at a ratio of 1:10). Multivariate conditional logistic regression models were used to evaluate the association between exposure to influenza (timing and cumulative number) and risk of lung cancer.

RESULTS

We identified 32,063 cases and 320,627 matched controls. Influenza was associated with a 1.09-fold increased risk of lung cancer (aOR 1.09, 95% CI 1.04-1.14, p<0.0001). The risk of lung cancer increased slightly with cumulative exposure to influenza (1-2 exposures: aOR 1.05, 95% CI 1.00-1.11; 3-4 exposures: aOR 1.12, 95% CI 1.00-1.25; 5+ exposures: aOR 1.25, 95% CI 1.13-1.39).

CONCLUSION

Exposure to influenza was associated with an increased risk of lung cancer and the risk increased with cumulative exposure to influenza. However, the lack of valid information on smoking could lead to confounding, and future studies collecting patients' smoking histories are warranted to validate the association between influenza and lung cancer.

Identification of candidate genes associated with the pathogenesis of small cell lung cancer via integrated bioinformatics analysis

The pathogenesis of small cell lung cancer (SCLC), a highly metastatic malignant tumor, remains unclear. In the present study, important genes and pathways that are involved in the pathogenesis of SCLC were identified. The following four datasets were downloaded from the Gene Expression Omnibus: GSE60052, GSE43346, GSE15240 and GSE6044. The differentially expressed genes (DEGs) between the SCLC samples and the normal samples were analyzed using R software. The limma package was used for every dataset. The RobustRankAggreg package was used to integrate the DEGs from the four datasets. Functional and pathway enrichment analyses were conducted using the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases with FunRich software and R software, respectively. In addition, the protein-protein interaction (PPI) network of the DEGs was constructed using the STRING database and Cytoscape software. Hub genes and significant modules were identified using Molecular Complex Detection in Cytoscape software. Finally, the expression values of hub genes were determined using the Oncomine online database. In total, 412 DEGs were identified following the integration of the four datasets, with 146 upregulated genes and 266 downregulated genes. The upregulated DEGs were primarily enriched in the cell cycle, cell division and microtubule binding. The downregulated DEGs were primarily enriched in the complement and coagulation cascades, the cytokine-mediated signaling pathway and protein binding. Eight hub genes and 1 significant module correlated to the cell cycle pathway were identified based on a subset of the PPI network. Finally, five hub genes were identified as highly expressed in SCLC tissue compared with normal tissue. The cell cycle pathway may be the pathway most closely associated with the pathogenesis of SCLC. NDC80, BUB1B, PLK1, CDC20 and MAD2L1 should be the focus of follow-up studies regarding the diagnosis and treatment of SCLC.

Biomass fuel as a risk factor for esophageal squamous cell carcinoma: a systematic review and meta-analysis

BACKGROUND

The link between use of solid biomass fuel (wood, charcoal, coal, dung, and crop residues) for cooking and/or heating and esophageal squamous cell carcinoma (ESCC) is inconclusive.

OBJECTIVE

We systematically reviewed the literature and performed a meta-analysis to determine whether cooking fuel type influences esophageal squamous cell carcinoma.

METHODS

We searched MEDLINE, EMBASE, Web of Knowledge and Cochrane Database of Systematic Reviews for studies investigating cooking fuel and ESCC from 2000 until March 2019. We performed random effects meta-analysis stratified by the continent, World Bank's country income classifications and fuel type and calculated pooled odds ratios and 95% CIs for the risk of esophageal squamous cell carcinoma in biomass fuel users compared with non-users.

RESULTS

Our analysis included 16 studies (all case-control) with 16,189 participants (5233 cases and 10,956 controls) that compared risk of ESCC among those using nonsolid fuels and biomass fuels. We found use of biomass fuel was associated with Esophageal squamous cell carcinoma with a pooled odds ratio (OR) 3.02 (95% CI 2.22, 4.11, heterogeneity (I2) = 79%). In sub-group analyses by continent, Africa (OR 3.35, 95%CI 2.34, 4.80, I2 = 73.4%) and Asia (OR 3.08, 95%CI 1.27, 7.43, I2 = 81.7%) had the highest odds of ESCC. Use of wood as fuel had the highest odds of 3.90, 95% CI 2.25, 6.77, I2 = 63.5%). No significant publication bias was detected.

CONCLUSIONS

Biomass fuel is associated with increased risk of Esophageal squamous cell carcinoma. Biomass fuel status should be considered in the risk assessment for Esophageal squamous cell carcinoma.

The establishment of the Household Air Pollution Consortium (HAPCO)

Household air pollution (HAP) is of public health concern with ~3 billion people worldwide (including >15 million in the US) exposed. HAP from coal use is a human lung carcinogen, yet the epidemiological evidence on carcinogenicity of HAP from biomass use, primarily wood, is not conclusive. To robustly assess biomass's carcinogenic potential, prospective studies of individuals experiencing a variety of HAP exposures are needed. We have built a global consortium of 13 prospective cohorts (HAPCO: Household Air Pollution Consortium) that have site- and disease-specific mortality and solid fuel use data, for a combined sample size of 587,257 participants and 57,483 deaths. HAPCO provides a novel opportunity to assess the association of HAP with lung cancer death while controlling for important confounders such as tobacco and outdoor air pollution exposures. HAPCO is also uniquely positioned to determine the risks associated with cancers other than lung as well as non-malignant respiratory and cardiometabolic outcomes, for which prospective epidemiologic research is limited. HAPCO will facilitate research to address public health concerns associated with HAP-attributed exposures by enabling investigators to evaluate sex-specific and smoking status-specific effects under various exposure scenarios.

Lung cancer family history and exposure to occupational/domestic coal combustion contribute to variations in clinicopathologic features and gene fusion patterns in non-small cell lung cancer

BACKGROUND

Both genetic and environmental factors contribute to the development of cancer and its mutant spectrum. Lung cancer has familial aggregation. Lung cancer caused by non-tobacco factors has unique pathological and molecular characteristics. The interaction between genetic lung cancer susceptibility and carcinogens from coal burning remains complex and understudied.

METHODS

We selected 410 non-small cell lung cancer (NSCLC) patients with a family history of lung cancer (FLC) and exposure to coal combustion between 2014 and 2017. Clinicopathologic parameters were analyzed. Reverse transcription-PCR was performed to detect ALK, ROS1, RET, and NTRK1 rearrangement.

RESULTS

Among the 410 NSCLC patients, 192 had FLC and 204 (49.8%) were exposed to occupational or domestic coal combustion. FLC patients had the same characteristics regardless of gender and coal exposure: younger age, high female ratio, adenocarcinoma, increased metastasis, later stage at diagnosis, and higher frequency of gene fusion. Sixty-seven patients (16.3%) had gene rearrangement: 51 (12.4%) harbored EML4-ALK fusions and 16 ROS1 fusions (3.9%). The highest gene fusion rate (35.1%, 33/94) occurred in patients with both FLC and high tobacco and coal exposure. ALK fusions and total gene rearrangement were closely associated with women, never smokers, younger age, FLC, and coal exposure.

CONCLUSION

FLC and exposure to coal combustion have an important impact on the clinicopathological characteristics and gene fusion mode of NSCLC, particularly in cases of higher levels of carcinogens, and genetic susceptibility has a greater impact. Our findings may help evaluate the effect of FLC and coal exposure on the pathogenesis of lung cancer.

Global Epidemiology of Lung Cancer

While lung cancer has been the leading cause of cancer-related deaths for many years in the United States, incidence and mortality statistics - among other measures - vary widely worldwide. The aim of this study was to review the evidence on lung cancer epidemiology, including data of international scope with comparisons of economically, socially, and biologically different patient groups. In industrialized nations, evolving social and cultural smoking patterns have led to rising or plateauing rates of lung cancer in women, lagging the long-declining smoking and cancer incidence rates in men. In contrast, emerging economies vary widely in smoking practices and cancer incidence but commonly also harbor risks from environmental exposures, particularly widespread air pollution. Recent research has also revealed clinical, radiologic, and pathologic correlates, leading to greater knowledge in molecular profiling and targeted therapeutics, as well as an emphasis on the rising incidence of adenocarcinoma histology. Furthermore, emergent evidence about the benefits of lung cancer screening has led to efforts to identify high-risk smokers and development of prediction tools. This review also includes a discussion on the epidemiologic characteristics of special groups including women and nonsmokers. Varying trends in smoking largely dictate international patterns in lung cancer incidence and mortality. With declining smoking rates in developed countries and knowledge gains made through molecular profiling of tumors, the emergence of new risk factors and disease features will lead to changes in the landscape of lung cancer epidemiology.

Indoor air pollution in rural north-east India: Elemental compositions, changes in haematological indices, oxidative stress and health risks

Chronic smoke exposure, emitted by biomass fuel burning leads to many diseases, which are originated due to oxidative stress. The present study investigated the levels of PM_2.5, PM₁₀ and PM_2.5 bound trace metals released during cooking with fuelwood and subsequent changes in haematological parameters along with oxidative stress in rural tribal women of northeast India exposed to wood smoke. The levels of PM_2.5, PM₁₀ and trace metals associated with PM_2.5 (nickel, cobalt, manganese, zinc, cadmium, lead and copper) were measured. In addition, blood samples were analyzed for concentrations of different blood related parameters (haemoglobin, platelet count, red blood cells and white blood cells) and levels of antioxidants (reduced glutathione, superoxide dismutase, and catalase). Plasma malondialdehyde (MDA) was measured as a biomarker of lipid peroxidation. Health risk assessment was done to assess the potential risk posed by inhalation of fine particles emitted from cooking with fuel wood. Levels of both PM_2.5 and PM₁₀ were higher in wood users compared to LPG users during cooking period (644.4 ± 368.3 µg/m³ vs 50 ± 23.8 µg/m³; 915 ± 441.3 µg/m³ vs 83.3 ± 33 µg/m³) and it exceeded the permissible limits of WHO. Levels of trace metals during the cooking period in fuel wood users were significantly higher than LPG users (p = 0.01). After controlling possible confounders, both platelet count and white blood cells (WBC) had a significant positive association with PM_2.5and PM₁₀. Similarly, haemoglobin had a negative association with both PM_2.5 and PM₁₀. Depleted levels of antioxidant enzymes and increase in lipid peroxidation (MDA) suggest a close association with pollutants released from wood smoke, indicating oxidative stress in women who used fuelwood for cooking. The total hazard quotient (HQ) of 0.11 was within the acceptable limit (i.e., 1.0). The total excess lifetime cancer risk (ELCR) was 5.4 × 10^-6 which is five times higher than the acceptable limit of 1.0 × 10^-6. Individual carcinogenic risk of Ni (2.3 × 10^-6) and Cd (3.1 × 10^-6) were also higher compared to acceptable limit. These results indicate that tribal women cooking with wood are at greater risk of developing cancer and also give support to the positive association between wood smoke and oxidative stress.

Identification of genes and analysis of prognostic values in nonsmoking females with non-small cell lung carcinoma by bioinformatics analyses

Background

This study was performed to identify disease-related genes and analyze prognostic values in nonsmoking females with non-small cell lung carcinoma (NSCLC).

Materials and methods

Gene expression profile GSE19804 was downloaded from the Gene Expression Omnibus (GEO) database and analyzed by using GEO2R. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes were used for the functional and pathway enrichment analysis. Then, the Search Tool for the Retrieval of Interacting Genes, Cytoscape, and Molecular Complex Detection were used to construct the protein–protein interaction (PPI) network and identify hub genes. Finally, the Kaplan–Meier plotter online tool was used for the overall survival analysis of hub genes.

Results

A cohort of 699 differentially expressed genes was screened, and they were mainly enriched in the terms of ECM–receptor interaction, focal adhesion, and cell adhesion molecules. A PPI network was constructed, and 15 hub genes were identified base on the subset of PPI network. Then, two significant modules were detected and several genes were found to be associated with the cell cycle pathway. Finally, nine hub genes’ (UBE2C, DLGAP5, TPX2, CCNB2, BIRC5, KIF20A, TOP2A, GNG11, and ANXA1) expressions were found to be associated with the prognosis of the patients.

Conclusion

Overall, we propose that the cell cycle pathway may play an important role in nonsmoking females with NSCLC and the nine hub genes may be further explored as potential targets for NSCLC diagnosis and treatment.

Smoking as a risk factor for lung cancer in women and men: a systematic review and meta-analysis

OBJECTIVES

To investigate the sex-specific association between smoking and lung cancer.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

We searched PubMed and EMBASE from 1 January 1999 to 15 April 2016 for cohort studies. Cohort studies before 1 January 1999 were retrieved from a previous meta-analysis. Individual participant data from three sources were also available to supplement analyses of published literature.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Cohort studies reporting the sex-specific relative risk (RR) of lung cancer associated with smoking.

RESULTS

Data from 29 studies representing 99 cohort studies, 7 million individuals and >50 000 incident lung cancer cases were included. The sex-specific RRs and their ratio comparing women with men were pooled using random-effects meta-analysis with inverse-variance weighting. The pooled multiple-adjusted lung cancer RR was 6.99 (95% Confidence Interval (CI) 5.09 to 9.59) in women and 7.33 (95% CI 4.90 to 10.96) in men. The pooled ratio of the RRs was 0.92 (95% CI 0.72 to 1.16; I2=89%; p<0.001), with no evidence of publication bias or differences across major pre-defined participant and study subtypes. The women-to-men ratio of RRs was 0.99 (95% CI 0.65 to 1.52), 1.11 (95% CI 0.75 to 1.64) and 0.94 (95% CI 0.69 to 1.30), for light, moderate and heavy smoking, respectively.

CONCLUSIONS

Smoking yields similar risks of lung cancer in women compared with men. However, these data may underestimate the true risks of lung cancer among women, as the smoking epidemic has not yet reached full maturity in women. Continued efforts to measure the sex-specific association of smoking and lung cancer are required.

Association between air pollution from residential wood burning and dementia incidence in a longitudinal study in Northern Sweden

Objectives

There is highly suggestive evidence for an effect of air pollution exposure on dementia-related outcomes, but evidence is not yet present to clearly pinpoint which pollutants are the probable causal agents. The aims of this study was to assess the longitudinal association between exposures of fine ambient particulate matter (PM_2.5) from residential wood burning, and vehicle exhaust, with dementia.

Method

We used data from the Betula study, a longitudinal study of dementia in Umeå, Northern Sweden. The study size was 1 806 and the participants were followed from study entry (1993–1995) to 2010. Modelled levels of source-specific fine particulate matter at the residential address were combined with information on wood stoves or wood boilers, and with validated data on dementia diagnosis and individual-level characteristics from the Betula study. Cox proportional hazards models were used to estimate Hazard Ratios (HRs) and their 95% CIs for dementia incidence (vascular dementia and Alzheimer’s disease), adjusted for individual-level characteristics.

Results

The emission of PM_2.5 from local residential wood burning was associated with dementia incidence with a hazard ratio of 1.55 for a 1 μg/m³ increase in PM_2.5 (95% Confidence Interval (CI): 1.00–2.41, p-value 0.05). Study participants with an address in an area with the highest quartile of PM_2.5 from residential wood burning and who also had a wood-burning stove were more likely to develop dementia than those in the lower three quartiles without a wood-burning stove with hazard ratios of 1.74 (CI: 1.10–2.75, p-value 0.018). Particulate matter from traffic exhaust seemed to be associated with dementia incidence with hazard ratios of 1.66, (CI: 1.16–2.39), p-value 0.006, and 1.41 (CI: 0.97–2.23), p-value 0.07, in the third and fourth quartiles, respectively.

Conclusions

If the associations we observed are causal, then air pollution from residential wood burning, and air pollution from traffic, might be independent important risk factors for dementia.

A Comparison of the Health Effects of Ambient Particulate Matter Air Pollution from Five Emission Sources

This article briefly reviews evidence of health effects associated with exposure to particulate matter (PM) air pollution from five common outdoor emission sources: traffic, coal-fired power stations, diesel exhaust, domestic wood combustion heaters, and crustal dust. The principal purpose of this review is to compare the evidence of health effects associated with these different sources with a view to answering the question: Is exposure to PM from some emission sources associated with worse health outcomes than exposure to PM from other sources? Answering this question will help inform development of air pollution regulations and environmental policy that maximises health benefits. Understanding the health effects of exposure to components of PM and source-specific PM are active fields of investigation. However, the different methods that have been used in epidemiological studies, along with the differences in populations, emission sources, and ambient air pollution mixtures between studies, make the comparison of results between studies problematic. While there is some evidence that PM from traffic and coal-fired power station emissions may elicit greater health effects compared to PM from other sources, overall the evidence to date does not indicate a clear ‘hierarchy’ of harmfulness for PM from different emission sources. Further investigations of the health effects of source-specific PM with more advanced approaches to exposure modeling, measurement, and statistics, are required before changing the current public health protection approach of minimising exposure to total PM mass.

Risk factors of Lung Cancer in nonsmoker

Generally, the cause of lung cancer is attributed to tobacco smoking. But many of the new lung cancer cases have been reported in nonsmokers. Apart from smoking; air pollution, environmental exposure, mutations, and single-nucleotide polymorphisms are known to be associated with lung cancer. Improper diet, alcohol consumption, marijuana smoking, estrogen, infections with human papillomavirus (HPV), HIV, and Epstein-Barr virus are suggested to be linked with lung cancer but clear evidences to ascertain their relation is not available. This article provides a comprehensive review of various risk factors and the underlying molecular mechanisms responsible for increasing the incidence of lung cancer. The pathologic, histologic, and genetic differences exist with lung cancer among smokers and nonsmokers. A better understanding of the risk factors, differences in pathology and molecular features of lung cancer in smokers and nonsmokers and the mode of action of various carcinogens will facilitate the prevention and management of lung cancer.

Indoor Wood-Burning Stove and Fireplace Use and Breast Cancer in a Prospective Cohort Study

BACKGROUND

Indoor burning of fuel for heating or cooking releases carcinogens. Little is known about the impact of indoor air pollution from wood-burning stoves or fireplaces on breast cancer risk.

OBJECTIVES

In a large prospective cohort study, we evaluated the risk of breast cancer in relation to indoor heating and cooking practices.

METHODS

Sister Study participants (n=50,884) were recruited from 2003–2009. Breast cancer–free women in the United States or Puerto Rico, 35–74 y old, with a sister with breast cancer were eligible. Participants completed questionnaires on indoor heating and cooking practices for both their enrollment and their longest adult residence. Cox regression was used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the association between indoor heating/cooking and breast cancer.

RESULTS

A total of 2,416 breast cancer cases were diagnosed during follow-up (mean=6.4 y). Having an indoor wood-burning stove/fireplace in the longest adult residence was associated with a higher breast cancer risk [HR=1.11 (95% CI: 1.01, 1.22)]; the risk increased with average frequency of use [≥once/week, HR=1.17 (95% CI: 1.02, 1.34)] (p for trend=0.01). An elevated HR was seen for women burning wood [HR=1.09 (95% CI: 0.98, 1.21)] or natural gas/propane [HR=1.15 (95% CI: 1.00, 1.32)]. No association was observed for burning artificial fire-logs [HR=0.98 (95% CI: 0.85, 1.12)] except among women from western states [HR=1.36 (95% CI: 1.02, 1.81)].

CONCLUSIONS

In this prospective study, using an indoor wood-burning stove/fireplace in the longest adult residence at least once a week and burning either wood or natural gas/propane was associated with a modestly higher risk of breast cancer. https://doi.org/10.1289/EHP827.

Firewood, smoke and respiratory diseases in developing countries-The neglected role of outdoor cooking

Smoke from cooking in the kitchen is one of the world’s leading causes of premature child death, claiming the lives of 500,000 children under five annually. This study analyses the role of outdoor cooking and the prevalence of respiratory diseases among children under five years by means of probit regressions using information from 41 surveys conducted in 30 developing countries from Asia, Africa and Latin America. I find that outdoor cooking reduces respiratory diseases among young children aged 0-4 by around 9 percent, an effect that reaches 13 percent among children aged 0-1. The results suggest that simple behavioral interventions, such as promoting outdoor cooking, can have a substantial impact on health hazards.