Occupational exposure to diesel motor exhaust and risk of lung cancer by histological subtype: a population-based case-control study in Swedish men

Lifestyle, Environmental, Occupational, and Dietary Risk Factors in Small-Cell vs. Non-Small-Cell Advanced Lung Cancer Patients: Is There a Connection?

OBJECTIVES

(i) To evaluate the possible exposure of newly diagnosed lung cancer patients to selected lifestyle, environmental, occupational, and dietary risk factors and (ii) to assess the differences in exposures of small-cell (SCLC) and non-small-cell (NSCLC) lung cancer patients to those risk factors.

METHODS

In this study, 205 newly diagnosed patients with IIIB/IV stage of either SCLC or NSCLC (111 men vs. 94 women) from Vojvodina, Serbia, were surveyed for selected demographic characteristics, dietary and lifestyle habits, and environmental factors.

RESULTS

Most patients were long-term heavy smokers. The body mass index values of SCLC patients were higher than those of NSCLC patients. Women reported higher stress levels compared to men. Women diagnosed with lung adenocarcinoma were more often exposed to traffic pollution compared to men. Individual indoor coal combustion systems were more often used by SCLC patients of both sexes compared to other cancer types. Men were more frequent consumers of canned foods, which are potential sources of endocrine disruptors. Occupational exposure to lung cancer risk factors, in addition to tobacco smoking, may be crucial in lung cancer development with specific occupations.

CONCLUSIONS

Further research on environmental and occupational risk factors for lung cancer is urgent in order to unveil the etiopathogenesis of specific lung cancer types.

Chronic diesel exhaust exposure induced pulmonary vascular remodeling a potential trajectory for traffic related pulmonary hypertension

BACKGROUND

As one of the most common traffic-related pollutants, diesel exhaust (DE) confers high risk for cardiovascular and respiratory diseases. However, its impact on pulmonary vessels is still unclear.

METHODS

To explore the effects of DE exposure on pulmonary vascular remodeling, our study analyzed the number and volume of small pulmonary vessels in the diesel engine testers (the DET group) from Luoyang Diesel Engine Factory and the controls (the non-DET group) from the local water company, using spirometry and carbon content in airway macrophage (CCAM) in sputum. And then we constructed a rat model of chronic DE exposure, in which 12 rats were divided into the DE group (6 rats with 16-week DE exposure) and the control group (6 rats with 16-week clean air exposure). During right heart catheterization, right ventricular systolic pressure (RVSP) was assessed by manometry. Macrophage migration inhibitory factor (MIF) in lung tissues and bronchoalveolar lavage fluid (BALF) were measured by qRT-PCR and ELISA, respectively. Histopathological analysis for cardiovascular remodeling was also performed.

RESULTS

In DET cohort, the number and volume of small pulmonary vessels in CT were positively correlated with CCAM in sputum (P<0.05). Rat model revealed that chronic DE-exposed rats had elevated RVSP, along with increased wall thickness of pulmonary small vessels and right the ventricle. What's more, the MIF levels in BALF and lung tissues were higher in DE-exposed rats than the controls.

CONCLUSION

Apart from airway remodeling, DE also induces pulmonary vascular remodeling, which will lead to cardiopulmonary dysfunction.

An umbrella review of the evidence associating occupational carcinogens and cancer risk at 19 anatomical sites

Occupational exposure to carcinogens of increasing cancer risk have been extensively suggested. A robust assessment of these evidence is needed to guide public policy and health care. We aimed to classify the strength of evidence for associations of 13 occupational carcinogens (OCs) and risk of cancers. We searched PubMed and Web of Science up to November 2022 to identify potentially relevant studies. We graded the evidence into convincing, highly suggestive, suggestive, weak, or not significant according to a standardized classification based on: random-effects p value, number of cancer cases, 95% confidence interval of largest study, heterogeneity between studies, 95% prediction interval, small study effect, excess significance bias and sensitivity analyses with credibility ceilings. The quality of meta-analysis was evaluated by AMSTAR 2. Forty-eight articles yielded 79 meta-analyses were included in current umbrella review. Evidence of associations were convincing (class I) or highly suggeastive (class II) for asbestos exposure and increasing risk of lung cancer among smokers (RR = 8.79, 95%CI: 5.81-13.25 for cohort studies and OR = 8.68, 95%CI: 5.68-13.24 for case-control studies), asbestos exposure and increasing risk of mesothelioma (RR = 4.61, 95%CI: 2.57-8.26), and formaldehyde exposure and increasing risk of sinonasal cancer (RR = 1.68, 95%CI: 1.38-2.05). Fifteen associations were supported by suggestive evidence (class III). In summary, the current umbrella review found strong associations between: asbestos exposure and increasing risk of lung cancer among smokers; asbestos exposure and increasing risk of mesothelioma; and formaldehyde exposure and higher risk of sinonasal cancer. Other associations might be genuine, but substantial uncertainty remains.

Dose-response-relationship between occupational exposure to diesel engine emissions and lung cancer risk: A systematic review and meta-analysis

BACKGROUND

In 2012, the International Agency for Research on Cancer (IARC) concluded that diesel engine emissions (DEE) emissions cause cancer in humans. However, there is still controversy surrounding this conclusion, due to several studies since the IARC decision citing a lack of evidence of a dose-response relationship.

OBJECTIVES

Through a systematic review, we aimed to evaluate all evidence on the association between occupational DEE and lung cancer to investigate whether there is an increased risk of lung cancer for workers exposed to DEE and if so, to describe the dose-response relationship.

METHODS

We registered the review protocol with PROSPERO and searched for observational studies in relevant literature databases. Two independent reviewers screened the studies' titles/abstracts and full texts, and extracted and assessed their quality. Studies with no direct DEE measurement but with information on length of exposure for high-risk occupations were assigned exposure values based on the DEE Job-Exposure-Matrix (DEE-JEM). After assessing quality and informativeness, we selected appropriate studies for the dose-response meta-analysis.

RESULTS

Sixty-five reports (from thirty-seven studies) were included in the review; one had a low risk of bias (RoB) (RR per 10 μg/m3-years: 1.014 [95%CI 1.007-1.021]). There was an increased, statistically significant risk of lung cancer with increasing DEE exposure for all studies (RR per 10 μg/m3-years = 1.013 [95%CI 1.004-1.021]) as well as for studies with a low RoB in the exposure category (RR per 10 μg/m3-years = 1.008 [95% CI1.001-1.015]). We obtained a doubling dose of 555 μg/m3-years for all studies and 880 μg/m3-years for studies with high quality in the exposure assessment.

DISCUSSION

We found a linear positive dose-response relationship for studies with high quality in the exposure domain, even though all studies had an overall high risk of bias. Current threshold levels for DEE exposure at the workplace should be reconsidered.

Risk factors for early-onset lung cancer in Korea: analysis of a nationally representative population-based cohort

OBJECTIVES

We examined the associations of socioeconomic factors, health behaviors, and comorbidities with early-onset lung cancer.

METHODS

The study included 6,794,287 individuals aged 20-39 years who participated in a Korean national health check-up program from 2009 to 2012. During the follow-up period, 4,684 participants developed lung cancer. Multivariable Cox regression analysis was used to estimate the independent associations of potential risk factors with incident lung cancer.

RESULTS

Older age (multivariable hazard ratio [mHR], 1.13; 95% confidence interval [CI], 1.12 to 1.14) and female sex (mHR, 1.62; 95% CI, 1.49 to 1.75) were associated with increased lung cancer risk. Current smoking was also associated with elevated risk (<10 pack-years: mHR, 1.12; 95% CI, 1.01 to 1.24; ≥10 pack-years: mHR, 1.30; 95% CI, 1.18 to 1.45), but past smoking was not. Although mild alcohol consumption (<10 g/day) was associated with lower lung cancer risk (mHR, 0.92; 95% CI, 0.86 to 0.99), heavier alcohol consumption (≥10 g/day) was not. Higher income (highest vs. lowest quartile: mHR, 0.86; 95% CI, 0.78 to 0.94), physical activity for at least 1,500 metabolic equivalent of task-min/wk (vs. non-exercisers: mHR, 0.83; 95% CI, 0.69 to 0.99) and obesity (vs. normal weight: mHR, 0.89; 95% CI, 0.83 to 0.96) were associated with lower lung cancer risk, whereas metabolic syndrome was associated with increased risk (mHR, 1.13; 95% CI, 1.03 to 1.24).

CONCLUSIONS

In young adults, age, female sex, smoking, and metabolic syndrome were risk factors for early-onset lung cancer, while high income, physical activity, and obesity displayed protective effects.

The Diesel Exhaust in Miners Study (DEMS) II: Temporal Factors Related to Diesel Exhaust Exposure and Lung Cancer Mortality in the Nested Case-Control Study

BACKGROUND

The Diesel Exhaust in Miners Study (DEMS) was an important contributor to the International Agency for Research on Cancer reclassification of diesel exhaust as a Group I carcinogen and subsequent risk assessment. We extended the DEMS cohort follow-up by 18 y and the nested case-control study to include all newly identified lung cancer deaths and matched controls (DEMS II), nearly doubling the number of lung cancer deaths.

OBJECTIVE

Our purpose was to characterize the exposure-response relationship with a focus on the effects of timing of exposure and exposure cessation.

METHODS

We conducted a case-control study of lung cancer nested in a cohort of 12,315 workers in eight nonmetal mines (376 lung cancer deaths, 718 controls). Controls were selected from workers who were alive when the case died, individually matched on mine, sex, race/ethnicity, and birth year (within 5 y). Based on an extensive historical exposure assessment, we estimated respirable elemental carbon (REC), an index of diesel exposure, for each cohort member. Odds ratios (ORs) were estimated by conditional regression analyses controlling for smoking and other confounders. To evaluate time windows of exposure, we evaluated the joint OR patterns for cumulative REC within each of four preselected exposure time windows, < 5 , 5-9, 10-19, and ≥ 20 y prior to death/reference date, and we evaluated the interaction of cumulative exposure across time windows under additive and multiplicative forms for the joint association.

RESULTS

ORs increased with increasing 15-y lagged cumulative exposure, peaking with a tripling of risk for exposures of ∼ 950  to < 1,700   μ g / m 3 -y [OR = 3.23 ; 95% confidence interval (CI): 1.47, 7.10], followed by a plateau/decline among the heavily exposed (OR = 1.85 ; 95% CI: 0.85, 4.04). Patterns of risk by cumulative REC exposure varied across four exposure time windows (p homogeneity < 0.001 ), with ORs increasing for exposures accrued primarily 10-19 y prior to death (p trend < 0.001 ). Results provided little support for a waning of risk among workers whose exposures ceased for ≥ 20 y.

CONCLUSION

DEMS II findings provide insight into the exposure-response relationship between diesel exhaust and lung cancer mortality. The pronounced effect of exposures occurring in the window 10-19 y prior to death, the sustained risk 20 or more years after exposure ceases, and the plateau/decline in risk among the most heavily exposed provide direction for future research on the mechanism of diesel-induced carcinogenesis in addition to having important implications for the assessment of risk from diesel exhaust by regulatory agencies. https://doi.org/10.1289/EHP11980.

Scoping Review of 5 Common Occupational Cancers and Their Related Exposures

Background: Occupational cancers can be avoided by removing dangerous chemicals from the workplace or limiting occupational exposure. Approximately, 10 major risk factors account for 85% of all occupational cancers. This scoping review study aimed to determine the most important chemical carcinogens related to 5 known occupational cancers. Methods: In this scoping review, we followed Arksey and O'Malley's 5-step framework. Four databases (PubMed, Web of Science, Google Scholar, Scopus) were systematically reviewed for relevant published papers from January 2000 to September 2021. Studies were included in this scoping review, which examined the effect of carcinogenic (definite and probable) chemical exposures on 5 known occupational cancers (lung, bladder, laryngeal, leukemia, and liver). We reported the types of occupational carcinogens, the geographical diversity of studies, extraction of relative risks (RRs), hazard ratios (HRs), or odds ratios (ORs), and identified gaps in the existing literature. Results: The highest number of studies was related to lung cancer (LC) (n = 26), bladder cancer (BC) (n = 11), laryngeal cancer (LaC) (n = 8), leukemia (LeC) (n = 3), and primary liver cancer (PLC) (n = 2), respectively. Most studies were performed in France and Canada (n = 8), Germany (n = 4), Finland (n = 3), Netherlands (n = 2), and Finland (n = 2), respectively. Furthermore, the most common occupational chemical carcinogens associated with the 5 known occupational cancers were asbestos, benzene, crystalline silica, polycyclic aromatic hydrocarbons (PAH), and diesel motor exhausts (DME). Conclusion: Although the attributable risk of occupational cancers in developing countries is much higher, a small proportion of studies were performed in these countries.

[Primary lung cancer and occupational exposure in a North African population]

Les cancers broncho-pulmonaires (CBP) sont parmi les cancers les plus fréquents, de pronostic redoutable, l´origine professionnelle est fréquente, mais souvent sous-estimés. L'objectif était d´évaluer la proportion des Cancers Broncho-pulmonaires (CBP) présumés d´origine professionnelle et de rechercher la relation entre la nature de l´exposition et le type histologique du CBP. Cette étude épidémiologique rétrospective, a été réalisée au service de pneumologie de l´Etablissement Public Hospitalier (EPH) de Rouïba. Entre janvier 2014 et juin 2019, nous avons colligé 357 cas atteints de CBP avec preuve histologique. Le recueil des histoires médicales et professionnelles fut effectué. Les matrices emploi-exposition ont été utilisées pour le repérage des différentes expositions professionnelles. La population d´étude comprenait 357 patients dont la moyenne d´âge était de 63,9±11,1 ans et un sex-ratio de 7,4 hommes pour une femme. Il y avait 76,5% des sujets qui fumaient ou avaient fumé en moyenne 42 P/A. Le type histologique était dans 88,8% un carcinome bronchique non à petite cellule. L'ensemble des professions étudiées seraient responsables de 50,7% des cancers bronchiques primitifs, dont 26,5% pour les professions de chauffeurs poids lourds et conducteurs d´engins. L´imputabilité des cancers broncho-pulmonaires (CBP) à l´origine professionnelle est loin d´être négligeable mais souvent méconnue; du fait du caractère multifactoriel et du temps de latence entre l´exposition et l´apparition de la maladie, avec un impact sur le type histologique du cancer broncho-pulmonaire.

The Associations of Aspirin, Statins, and Metformin With Lung Cancer Risk and Related Mortality: A Time-Dependent Analysis of Population-Based Nationally Representative Data

INTRODUCTION

The aim of this study was to investigate the associations of aspirin, metformin, and statins with lung cancer risk and mortality using population-based nationwide cohort data.

METHODS

This study included a total of 732,199 participants who underwent a national health check-up from 2002 to 2003. Lung cancer incidence and mortality were identified using a registered lung cancer diagnosis code (International Classification of Diseases, 10th revision, code C34) and the Korean National Death Registry. The study participants were followed up from January 1, 2004 to December 31, 2013. Medication exposure was defined by the cumulative duration of use and cumulative defined daily dose per 2-year interval. To avoid immortal-time bias, drug exposure was inserted as a time-dependent variable in Cox analysis, which evaluated the associations of these medications with lung cancer.

RESULTS

Metformin use had a protective association with lung cancer incidence (p's for trend 0.008) and mortality (p's for trend < 0.001) in a dose-response fashion, and these associations were prominent among participants with a metformin cumulative defined daily dose of 547.5 and above compared with patients without diabetes. Lung cancer mortality was dose-dependently reduced with the use of aspirin (p's for trends 0.046) and statin (p's for trends < 0.001). The combined use of aspirin, statins, and metformin exhibited more prominent protective associations with lung cancer risk and mortality.

CONCLUSIONS

The use of aspirin, metformin, and statins had independent protective associations with lung cancer mortality, and metformin had an inverse association with lung cancer risk. Further studies are necessary to develop clinically applicable anticancer strategies using these drugs for the reduction of lung cancer and related mortality.

Diesel Engine Exhaust Exposure, Smoking, and Lung Cancer Subtype Risks. A Pooled Exposure-Response Analysis of 14 Case-Control Studies

Rationale: Although the carcinogenicity of diesel engine exhaust has been demonstrated in multiple studies, little is known regarding exposure-response relationships associated with different exposure subgroups and different lung cancer subtypes.Objectives: We expanded on a previous pooled case-control analysis on diesel engine exhaust and lung cancer by including three additional studies and quantitative exposure assessment to evaluate lung cancer and subtype risks associated with occupational exposure to diesel exhaust characterized by elemental carbon (EC) concentrations.Methods: We used a quantitative EC job-exposure matrix for exposure assessment. Unconditional logistic regression models were used to calculate lung cancer odds ratios and 95% confidence intervals (CIs) associated with various metrics of EC exposure. Lung cancer excess lifetime risks (ELR) were calculated using life tables accounting for all-cause mortality. Additional stratified analyses by smoking history and lung cancer subtypes were performed in men.Measurements and Main Results: Our study included 16,901 lung cancer cases and 20,965 control subjects. In men, exposure response between EC and lung cancer was observed: odds ratios ranged from 1.09 (95% CI, 1.00-1.18) to 1.41 (95% CI, 1.30-1.52) for the lowest and highest cumulative exposure groups, respectively. EC-exposed men had elevated risks in all lung cancer subtypes investigated; associations were strongest for squamous and small cell carcinomas and weaker for adenocarcinoma. EC lung cancer exposure response was observed in men regardless of smoking history, including in never-smokers. ELR associated with 45 years of EC exposure at 50, 20, and 1 μg/m3 were 3.0%, 0.99%, and 0.04%, respectively, for both sexes combined.Conclusions: We observed a consistent exposure-response relationship between EC exposure and lung cancer in men. Reduction of workplace EC levels to background environmental levels will further reduce lung cancer ELR in exposed workers.

Histopathologic Analysis of Lung Cancer Incidence Associated with Radon Exposure among Ontario Uranium Miners

Although radon is a well-established contributor to lung cancer mortality among uranium miners, the effects of radon decay products on different histopathologies of lung carcinoma are not well established. Using a retrospective cohort design, this study aims to examine the risks of lung cancer by histological subtypes associated with exposure to radon decay products among the Ontario Uranium Miners cohort. Cases were stratified by histological groups, and associated risks were estimated for cumulative radon exposure after adjustment for attained age and calendar period. Between 1969 and 2005, 1274 incident cases of primary lung cancer were identified. Of these, 1256 diagnoses (99%) contained information on histology. Squamous cell carcinoma was most common (31%), followed by adenocarcinoma (20%), large cells (18%), small cell lung carcinoma (14%), and other or unspecified cell types (17%). Of the histological sub-groups, small cell lung carcinoma had the strongest association with cumulative radon exposure; compared to the reference group (<1 cumulative working level months (WLM)), the highest exposure category (>60 cumulative WLM) had a relative risk (RR) of 2.76 (95% CI: 1.67⁻4.57). Adenocarcinoma had the lowest risk and was not significantly associated with exposure to radon decay products (RR = 1.49, 95% CI: 0.96⁻2.31). An increasing, linear trend in relative risk was noted with increasing cumulative WLM across small cell, squamous cell, and large cell lung carcinomas (P_trend < 0.05). Similarly, the excess relative risk (ERR) per WLM was highest for small cell lung carcinoma (ERR/WLM = 0.15, p < 0.01), followed by squamous cell carcinoma (ERR/WLM = 0.12, p < 0.01). Non-statistically significant excess risk was observed for adenocarcinoma (ERR/WLM = 0.004, p = 0.07). Our analysis of the Ontario Uranium Miners cohort data shows differences in the magnitude of the risks across four histological subtypes of lung carcinoma; the strongest association was noted for small cell lung carcinoma, followed by squamous cell, large cell, and lastly adenocarcinoma, which showed no significant associations with exposure to radon decay products.

Amyotrophic Lateral Sclerosis and Exposure to Diesel Exhaust in a Danish Cohort

Previous studies have suggested an increased risk of amyotrophic lateral sclerosis (ALS) and other motor neuron diseases for persons in occupations commonly involving exposure to diesel exhaust (DE). In this study, we investigated the association between occupational exposure to DE and odds of ALS. ALS cases were identified from the Danish National Patient Registry (1982-2013) and individually matched to 100 controls per case on the basis of birth year and sex. Using information on occupational history from 1964 onward obtained from the Danish Pension Fund, we estimated cumulative DE exposures using a job exposure matrix. We evaluated associations using conditional logistic regression analyses and stratified the analyses by sex. Using a 10-year lag period, DE exposure was positively associated with ALS among men who had ever been exposed (adjusted odds ratio (aOR) = 1.20, 95% confidence interval (CI): 1.05, 1.38). For men with greater than 50% probability of DE exposure, we observed a positive association between ALS and highest-quartile exposure during the 5-year (aOR = 1.35, 95% CI: 1.07, 1.70) and 10-year (aOR = 1.41, 95% CI: 1.11, 1.79) lag periods. Our study suggests an association between consistently higher exposures to DE and ALS in men, but not in women. These findings support previous reports of associations between ALS and occupations commonly involving DE exposure.