Breast cancer among Danish women occupationally exposed to diesel exhaust and polycyclic aromatic hydrocarbons, 1964-2016

Risk of Gynecological and Breast Cancers in Workers Exposed to Diesel Exhaust: A Systematic Review and Meta-Analysis Of Cohort Studies

BACKGROUND

This study aimed to explore the association between occupational exposure to diesel exhaust (DE) and gynaecological and breast cancers.

METHODS

A systematic review was performed to identify cohort studies reporting results on the association between occupational exposure to DE and risk of gynaecological and breast cancers. STROBE guidelines and PECOS criteria were followed. We identified 6 studies for breast cancer (BC), 4 for cervical cancer (CC), 4 for endometrial cancer (EC) and 7 for ovarian cancer (OC). Random-effects meta-analyses were conducted on the relationship between DE exposure and BC, CC, EC, and OC risk; 95% confidence intervals (CI) and prediction intervals (PI) were reported. We investigated between-study heterogeneity and potential publication bias using Egger's test.

RESULTS

No associations were observed between occupational DE exposure and risk of BC [RR=0.93; CI: 0.77-1.13; PI:0.50-1.73, I2=80.31%], EC [RR=0.89; CI: 0.75-1.05; PI:0.61-1.30, I2=0.78%], and OC [RR=1.08; CI: 0.89-1.32, PI: 0.76-1.56, I2=11.87%]. A weak association was observed for CC [RR=1.41; CI: 1.17-1.17; PI:0.85-2.30, I2=6.44%]. No between-study heterogeneity or publication bias was detected.

CONCLUSIONS

This study identified an association between DE exposure and CC, which was not adjusted for potential confounders. No evidence of an association was found with BC, EC, and OC.

Exposure to outdoor ambient air toxics and risk of breast cancer: The multiethnic cohort

BACKGROUND

A growing literature has reported associations between traffic-related air pollution and breast cancer, however there are fewer investigations into specific ambient agents and any putative risk of breast cancer development, particularly studies occurring in populations residing in higher pollution areas such as Los Angeles.

OBJECTIVES

To estimate breast cancer risks related to ambient air toxics exposure at residential addresses.

METHODS

We examined the relationships between ambient air toxics and breast cancer risk in the Multiethnic Cohort among 48,665 California female participants followed for cancer from 2003 through 2013. We obtained exposure data on chemicals acting as endocrine disruptors or mammary gland carcinogens from the National-Scale Air Toxics Assessment. Cox proportional hazards models were used to estimate breast cancer risk per one interquartile range (IQR) increase in air toxics exposure lagged by 5-years. Stratified analyses were conducted by race, ethnicity, and hormone receptor types.

RESULTS

Among all women, increased risks of invasive breast cancer were observed with toxicants related to industries [1,1,2,2-tetrachloroethane (hazard ratio [HR] = 4.22, 95% confidence interval [95% CI] 3.18-5.60), ethylene dichloride (HR = 2.81, 95% CI 2.20-3.59), and vinyl chloride (HR = 2.27, 95% CI 1.81, 2.85); these 3 agents were correlated (r2 = 0.45-0.77)]. Agents related to gasoline production or combustion were related to increased breast cancer risk [benzene (HR = 1.32, 95% CI 1.24, 1.41), ethylbenzene (HR = 1.20, 95% CI 1.13-1.28), toluene (HR = 1.29, 95% CI 1.20-1.38), naphthalene (HR = 1.11, 95% CI 1.02-2.22), acrolein (HR = 2.26, 95% CI 1.92, 2.65)]. Higher hazard ratios were observed in African Americans and Whites compared to other racial and ethnic groups (p-heterogeneity <0.05 for traffic-related air toxics, acrolein, and vinyl acetate).

CONCLUSIONS

Our findings suggest that specific toxic air pollutants may be associated with increase breast cancer risk.

Mechanisms of breast cancer progression induced by environment-polluting aryl hydrocarbon receptor agonists

Breast cancer is the most common invasive malignancy among women worldwide and constitutes a complex and heterogeneous disease. Interest has recently grown in the role of the aryl hydrocarbon receptor (AhR) in breast cancer and the contribution of environment-polluting AhR agonists. Here, we present a literature review addressing AhR ligands, including pesticides hexachlorobenzene and chlorpyrifos, polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, parabens, and phthalates. The objectives of this review are a) to summarize recent original experimental, preclinical, and clinical studies on the biological mechanisms of AhR agonists which interfere with the regulation of breast endocrine functions, and b) to examine the biological effects of AhR ligands and their impact on breast cancer development and progression. We discuss biological mechanisms of action in cell viability, cell cycle, proliferation, epigenetic changes, epithelial to mesenchymal transition, and cell migration and invasion. In addition, we examine the effects of AhR ligands on angiogenic processes, metastasis, chemoresistance, and stem cell renewal. We conclude that exposure to AhR agonists stimulates pathways that promote breast cancer development and may contribute to tumor progression. Given the massive use of industrial and agricultural chemicals, ongoing evaluation of their effects in laboratory assays and preclinical studies in breast cancer at environmentally relevant doses is deemed essential. Likewise, awareness should be raised in the population regarding the most harmful toxicants to eradicate or minimize their use.

Geospatial Associations between Female Breast Cancer Mortality Rates and Environmental Socioeconomic Indicators for North Carolina

In North Carolina, over 6000 women will be diagnosed with breast cancer yearly, and over 1000 will die. It is well known that environmental conditions contribute greatly to health outcomes, and many of these factors include a geographic component. Using death data records from 2003-2019 extracted from North Carolina Vital Statistics Dataverse, a spatial database was developed to map and analyze female breast cancer mortality rates at the ZIP code scale in North Carolina. Thirty-nine hot spots and thirty cold spots of age-adjusted death rates were identified using the Getis-Ord analysis. Two-tailed t-tests were run between each cohort for environmental socioeconomic-related factors associated with breast cancer progression and mortality. The median age and household income of individuals who resided in ZIP codes with the highest breast cancer mortality were significantly lower than those who lived in ZIP codes with lower breast cancer mortality. The poverty rate, percentage of SNAP benefits, and the percentage of minorities were all significantly higher (p < 0.05, p < 0.001, and p < 0.001) in ZIP codes with high breast cancer rates. High-quality (ZIP code) granular cancer data were developed for which detailed analysis can be performed for future studies.

Parental occupational exposure to chemicals and risk of breast cancer in female offspring

OBJECTIVES

Parental exposure to chemicals at work has been hypothesized to be a potential predisposing factor for breast cancer in next generations. The objective of the present nationwide nested case-control study was to contribute with evidence to this area.

METHODS

Women with primary breast cancer were identified using the Danish Cancer Registry and they were required to have information on either maternal or paternal employment history, which resulted in the inclusion of 5587 cases. For each case, 20 female cancer free controls were matched on year of birth using the Danish Civil Registration System. Employment history was linked to job exposure matrices to assess specific occupational chemical exposures.

RESULTS

For maternal exposures, we observed an association between ever exposure to diesel exhaust (OR = 1.13, 95% CI: 1.01-1.27) and exposure to bitumen fumes in the perinatal period (OR = 1.51, 95% CI: 1.00-2.26) and breast cancer in female offspring. Highest cumulative exposure to benzo(a)pyrene, diesel exhaust, gasoline and bitumen fumes was further indicated to increase the risk. Results further indicated a stronger association between diesel exhaust (OR = 1.23, 95% CI: 1.01-1.50) and benzo(a)pyrene exposure (OR = 1.23, 95% CI: 0.96-1.57) and estrogen receptor negative tumors than tumors with ER expression, while bitumen fumes seemed to elevate the risk of both hormonal subtypes. For paternal exposures, the main results did not indicate any associations with breast cancer in female offspring.

CONCLUSIONS

Our study suggests an elevated breast cancer risk in daughters of women occupational exposed to some occupational pollutants, including diesel exhaust, benzo(a)pyrene and bitumen fumes. These findings need to be confirmed in future large-scale studies before any firm conclusions can be reached.

HDAC inhibitor HPTA initiates anti-tumor response by CXCL9/10-recruited CXCR3+CD4+T cells against PAHs carcinogenicity

Polycyclic aromatic hydrocarbons (PAHs) exposure in food is closely associated with the occurrence and development of breast cancer, which may attribute to altered immunotoxicity and immune regulation. Currently, cancer immunotherapy aims to promote tumor-specific T cell responses, especially CD4⁺T helper cells (Th) for anti-tumor immunity. The histone deacetylase inhibitors (HDACis) are found to exert an anti-tumor effect by reshaping the tumor immune microenvironment, but the immune regulatory mechanism of HDACis in PAHs-induced breast tumor remains elusive. Here, using established breast cancer models induced by 7,12-dimethylbenz[a]anthracene (DMBA), a potent carcinogenic agent of PAH, the novel HDACi, 2-hexyl-4-pentylene acid (HPTA) exhibited anti-tumor effect by activating T lymphocytes immune function. HPTA recruited CXCR3⁺CD4⁺T cells into chemokines CXCL9/10-enriched tumor sites, the increased secretion of CXCL9/10 was regulated by the NF-κB-mediated pathway. Furthermore, HPTA promoted Th1 differentiation and assisted cytotoxic CD8⁺T cells in the elimination of breast cancer cells. These findings support the proposition of HPTA as a potential therapeutic in the treatment of PAHs-induced carcinogenicity.

The relationship between tobacco and breast cancer incidence: A systematic review and meta-analysis of observational studies

Background

The effect of tobacco on breast cancer (BC) is controversial. The purpose of this study was to investigate the relationship between tobacco and BC.

Methods

A search was conducted in PubMed, EBSCO, Web of Science and Cochrane Library databases before February 2022. The adjusted odd ratio (OR) and corresponding 95% confidence interval (CI) were used to examine the relationship between active or passive smoking and BC risk.

Results

A total of 77 articles composed of 2,326,987 participants were included for this meta-analysis. Active (OR=1.15, 95% CI=1.11-1.20, p&lt;0.001) and passive (OR=1.17, 95% CI=1.09-1.24, p&lt;0.001) smoking increased the risk of BC in the female population, especially premenopausal BC (active smoking: OR=1.24, p&lt;0.001; passive smoking: OR=1.29, p&lt;0.001), but had no effect on postmenopausal BC (active smoking: OR=1.03, p=0.314; passive smoking: OR=1.13, p=0.218). Active smoking increased the risk of estrogen receptor-positive (ER+) BC risk (OR=1.13, p&lt;0.001), but had no effect on estrogen receptor-negative (ER-) BC (OR=1.08, p=0.155). The risk of BC was positively associated with the duration and intensity of smoking, negatively associated with the duration of smoking cessation. Active smoking increased the risk of BC in the multiparous population (OR=1.13, p&lt;0.001), but had no effect on the nulliparous population (OR=1.05, p=0.432), and smoking before the first birth (OR=1.22, 95% CI=1.17-1.27) had a greater impact on the risk of BC than smoking after the first birth (OR=1.08, 95% CI=1.04-1.12).

Conclusion

Smoking (active and passive) increased the risk of BC in women. The effect of smoking on BC was influenced by smoking-related factors (duration, intensity, years of quitting), population-related factors (fertility status), and BC subtypes.

Systematic Review Registration

identifier CRD42022322699.

Breast Cancer Incidence among Female Workers by Different Occupations and Industries: A Longitudinal Population-Based Matched Case-Control Study in Taiwan

BACKGROUND

Breast cancer is the leading cause of cancer incidence worldwide and in Taiwan. The relationship between breast cancer and occupational types remains unclear. This study aimed to investigate lifetime breast cancer incidence by different occupational industries among female workers in Taiwan.

METHODS

A population-based retrospective case-control study was conducted using three nationwide population-based databases. Matched case and control groups were identified with 1-to-4 exact matching among 103,047 female workers with breast cancer diagnosed in 2008-2017 and those without breast cancer. Their lifetime labor enrollment records were tracked using the National Labor Insurance Database, 1950-2017. Conditional logistic regression was used to analyze the association between types of occupational industries and risk of incident breast cancer.

RESULTS

Our study found slightly significant breast cancer risk among the following major occupational classifications: manufacturing (OR: 1.027, 95% CI: 1.011-1.043); wholesale and retail trade (OR: 1.068, 95% CI: 1.052-1.084); information and communication (OR: 1.074, 95% CI: 1.043-1.105); financial and insurance activities (OR: 1.109, 95% CI: 1.086-1.133); real estate activities (OR: 1.050, 95% CI: 1.016-1.085); professional, scientific, and technical activities (OR: 1.118, 95% CI: 1.091-1.145); public administration, defense, and social security (OR: 1.054, 95% CI: 1.023-1.087), education (OR: 1.199, 95% CI: 1.168-1.230); and human health and social work activities (OR: 1.125, 95% CI: 1.096-1.156).

CONCLUSIONS

Greater percentages of industrial occupations (i.e., manufacturing, wholesale and retail, or health professionals) were associated with slightly increased breast cancer risk. Further studies should investigate the possible risk factors among female workers in those industries with slightly higher incidence of breast cancer.

Occupational Factors and Socioeconomic Differences in Breast Cancer Risk and Stage at Diagnosis in Swiss Working Women

Socioeconomic differences in breast cancer (BC) incidence are driven by differences in lifestyle, healthcare use and occupational exposure. Women of high socioeconomic status (SES) have a higher risk of BC, which is diagnosed at an earlier stage, than in low SES women. As the respective effects of occupation and SES remain unclear, we examined the relationships between occupation-related variables and BC incidence and stage when considering SES. Female residents of western Switzerland aged 18−65 years in the 1990 or 2000 census, with known occupation, were linked with records of five cancer registries to identify all primary invasive BC diagnosed between 1990 and 2014 in this region. Standardized incidence ratios (SIRs) were computed by occupation using general female population incidence rates, with correction for multiple comparisons. Associations between occupation factors and BC incidence and stage at diagnosis were analysed by negative binomial and multinomial logistic regression models, respectively. The cohort included 381,873 women-years and 8818 malignant BC, with a mean follow-up of 14.7 years. Compared with reference, three occupational groups predominantly associated with a high socioprofessional status had SIRs > 1: legal professionals (SIR = 1.68, 95%CI: 1.27−2.23), social science workers (SIR = 1.29; 95%CI: 1.12−1.49) and some office workers (SIR = 1.14; 95%CI: 1.09−1.20). Conversely, building caretakers and cleaners had a reduced incidence of BC (SIR = 0.69, 95%CI: 0.59−0.81). Gradients in BC risk with skill and socioprofessional levels persisted when accounting for SES. A higher incidence was generally associated with a higher probability of an early-stage BC. Occupation and SES may both contribute to differences in risk and stage at diagnosis of BC.

Employment and risk of female breast cancer in Denmark

BACKGROUND

Occupational exposures may play a role in breast cancer etiology, and research focusing on identifying high-risk workplaces is important to advance the understanding and prevention of breast cancer.

METHODS

We undertook a population-based nested case-control study among women who were less than 70 years of age and born in Denmark, based on registry data including 38,375 breast cancer cases and 191,875 controls matched on year of birth, with information on lifetime work history. Odds ratios for women ever employed in a job branch were adjusted for socioeconomic status and reproductive variables.

RESULTS

Adjusted odds ratios of less than 0.75 were observed for several occupations in agriculture, hunting, forestry, and fishing, while increased risk patterns (odds ratios greater than 1.50) were noted for a number of production occupations, including employment in graphics and printing, and metal and machinery production. In services, several military professions were also associated with a high increased breast cancer risk.

CONCLUSIONS

The study shows a variation in the risk of female breast cancer by employment in different industrial and occupational sectors, and suggests that certain occupational exposures, for example, outdoor work, organic solvents, polycyclic aromatic hydrocarbons (PAHs), and night-shift work may play a role in the risk of breast cancer. Further hypothesis-testing studies focusing on these employments with a detailed assessment of specific occupational exposures are warranted.