Assessing environmental and occupational risk factors for lung cancer in Mexican-Americans

Benzene Exposure and Lung Cancer Risk: A Systematic Review and Meta-Analysis of Human Studies

Lung cancer is a leading cause of death with nearly 1.8 million deaths estimated worldwide in 2020. Although benzene is classified as a human carcinogen (Group 1) on the basis of its association with acute myeloid/non-lymphocytic leukaemia, there is still limited evidence that it may influence lung cancer risk. This study examined the potential link between benzene exposure and risk of lung cancer using a systematic review of epidemiological studies and meta-analysis. We searched through PubMed, Web of Science and Scopus databases up to 10 February 2023 to identify all articles on the association between benzene exposure and lung cancer (incidence or prevalence) and/or mortality. We extracted the risk estimates of the highest and the lowest reported categories of benzene exposure and conducted a meta-analysis using a random-effects model. Heterogeneity and publication bias were analysed using an I2 test and funnel plots asymmetry, respectively. Twenty-one studies were included in the final analysis, with a total of 10,750 lung cancer cases and 2899 lung cancer deaths. Overall, risk estimates of lung cancer prevalence and mortality in association with benzene exposure were 1.20 (n = 14; 95% CI 1.05-1.37) and 1.15 (n = 13; 95% CI 1.02-1.30), respectively. In all cases, heterogeneity was quite large, while no significant publication bias was observed. When only studies that adjusted for smoking habit were selected, the risk for lung cancer increased by up to 34% (n = 9; 95% CI 1.10-1.64). Our data, which show a strong association between benzene exposure and lung cancer risk, may have important public health implications. However, further studies are needed to identify the lung cancer risk associated with benzene exposure considering different smoking conditions.

Structural Racism and Lung Cancer Risk: A Scoping Review

Importance

Structural racism is associated with persistent inequities in health and health outcomes in the US for racial and ethnic minority groups. This review summarizes how structural racism contributes to differential population-level exposure to lung cancer risk factors and thus disparate lung cancer risk across different racial and ethnic groups.

Observations

A scoping review was conducted focusing on structural racism and lung cancer risk for racial and ethnic minority groups. The domains of structural racism evaluated included housing and built environment, occupation and employment, health care, economic and educational opportunity, private industry, perceived stress and discrimination, and criminal justice involvement. The PubMed, Embase, and MedNar databases were searched for English-language studies in the US from January 1, 2010, through June 30, 2022. The review demonstrated that racial and ethnic minority groups are more likely to have environmental exposures to air pollution and known carcinogens due to segregation of neighborhoods and poor housing quality. In addition, racial and ethnic minority groups were more likely to have exposures to pesticides, silica, and asbestos secondary to higher employment in manual labor occupations. Furthermore, targeted marketing and advertisement of tobacco products by private industry were more likely to occur in neighborhoods with more racial and ethnic minority groups. In addition, poor access to primary care services and inequities in insurance status were associated with elevated lung cancer risk among racial and ethnic minority groups. Lastly, inequities in tobacco use and cessation services among individuals with criminal justice involvement had important implications for tobacco use among Black and Hispanic populations.

Conclusions and Relevance

The findings suggest that structural racism must be considered as a fundamental contributor to the unequal distribution of lung cancer risk factors and thus disparate lung cancer risk across different racial and ethnic groups. Additional research is needed to better identify mechanisms contributing to inequitable lung cancer risk and tailor preventive interventions.

Incidence of non-small-cell lung cancer among California Hispanics according to neighborhood socioeconomic status

INTRODUCTION

Lung cancer incidence is associated with markers of lower socioeconomic status (SES) in whites, blacks, and Asians but with markers of higher SES in Hispanics. The magnitude and etiology of this positive gradient in Hispanics remain undefined. We examined non-small-cell lung cancer (NSCLC) incidence and ever-smoking rates among California Hispanics according to measures of SES.

METHODS

We computed neighborhood (n)SES-specific incidence rates by sex and race or ethnicity for 74,179 NSCLC cases in the California Cancer Registry, 1998-2002. Associations between nSES and NSCLC incidence were examined, using incidence rate ratios and linear trend tests, and stratified by age, stage, and histology. Ever-smoking rates among Hispanics were obtained from California Health Interview Survey 2001 data, and odds ratios for ever-smoking were calculated for measures of SES and acculturation.

RESULTS

Compared with the lowest nSES quintile, the NSCLC incidence in the highest quintile was 1.86 and 1.18 times higher for Hispanic women and men, respectively. The positive nSES gradients remained significant for all ages, stages, and nonsquamous histologies in women, and only for older age, local or regional stages, and adenocarcinoma histology in men. Ever-smoking rates were associated with English-speaking households and U.S.-born status for Hispanic women and low education and U.S.-born status for Hispanic men.

CONCLUSIONS

For California Hispanics, higher nSES was strongly associated with increased NSCLC incidence in women, but weakly associated in men, and ever-smoking rates were strongly correlated with increased acculturation. This finding may portend an increasing burden of NSCLC in Hispanic women, given future trends in acculturation and SES.

Use of the cytokinesis-blocked micronucleus assay to detect gender differences and genetic instability in a lung cancer case-control study

BACKGROUND

Although tobacco exposure is the predominant risk factor for lung cancer, other environmental agents are established lung carcinogens. Measuring the genotoxic effect of environmental exposures remains equivocal, as increases in morbidity and mortality may be attributed to coexposures such as smoking.

METHODS

We evaluated genetic instability and risk of lung cancer associated with exposure to environmental agents (e.g., exhaust) and smoking among 500 lung cancer cases and 500 controls using the cytokinesis-blocked micronucleus (CBMN) assay. Linear regression was applied to estimate the adjusted means of the CBMN endpoints (micronuclei and nucleoplasmic bridges). Logistic regression analyses were used to estimate lung cancer risk and to control for potential confounding by age, gender, and smoking.

RESULTS

Cases showed significantly higher levels of micronuclei and nucleoplasmic bridges as compared with controls (mean ± SEM = 3.54 ± 0.04 vs. 1.81 ± 0.04 and mean ± SEM = 4.26 ± 0.03 vs. 0.99 ± 0.03, respectively; P < 0.001) with no differences among participants with or without reported environmental exposure. No differences were observed when stratified by smoking or environmental exposure among cases or controls. A difference in lung cancer risk was observed between nonexposed male and female heavy smokers, although it was not statistically significant (I(2) = 64.9%; P value for Q statistic = 0.09).

CONCLUSIONS

Our study confirms that the CBMN assay is an accurate predictor of lung cancer and supports the premise that heavy smoking may have an effect on DNA repair capacity and in turn modulate the risk of lung cancer.

IMPACT

Identifying factors that increase lung cancer risk may lead to more effective prevention measures.