Exploring exposure to Agent Orange and increased mortality due to bladder cancer

Exposures and Bladder Cancer Risk Among Military Veterans: A Systematic Review and Meta-analysis

OBJECTIVE

To investigate potential carcinogenic exposures in military personnel that are implicated in the development of bladder cancer.

METHODS

This systematic review aimed to evaluate the association between specific military exposures and bladder cancer risk among veterans. PubMed, Scopus, and Ovid MEDLINE databases were searched in December 2023 for relevant articles. Inclusion criteria comprised retrospective cohort studies, reviews, and observational studies documenting bladder cancer incidence among military populations exposed to specific agents. A total of 25 studies, involving 4,320,262 patients, met the inclusion criteria. Data extraction followed PRISMA guidelines, and a random-effects model was used for data synthesis.

RESULTS

The meta-analysis revealed significant associations between exposure to Agent Orange (HR 1.17 [95% CI: 1.01-1.36], P < .00001) and depleted uranium (HR 2.13 [95% CI: 1.31-3.48], P = .002) with increased bladder cancer risk among veterans. Contaminated drinking water showed a trend towards increased risk (HR 1.25 [95% CI: 0.97-1.61], P = .08).

CONCLUSION

The findings suggest a possible association between specific military exposures and heightened bladder cancer risk among veterans, emphasizing the necessity for targeted screening protocols and preventive measures. Further research is essential to identify specific carcinogenic agents and prevalence of exposures among veterans, enabling more effective prevention and management strategies.

The association between polychlorinated dibenzo-p-dioxin exposure and cancer mortality in the general population: a cohort study

Introduction

Earlier research has indicated that being exposed to polychlorinated dibenzo-p-dioxins (PCDDs) in the workplace can heighten the likelihood of cancer-related deaths. Nevertheless, there is limited information available regarding the connection between PCDD exposure and the risk of cancer mortality in the general population (i.e., individuals not exposed to these substances through their occupation).

Methods

The National Health and Nutrition Examination Survey (NHANES) detected PCDDs in the general population, and the death data were recently updated as of December 31, 2019. We conducted Cox regression analysis and controlled for covariates including age, gender, ethnicity, educational attainment, physical activity, alcohol intake, NHANES survey period, BMI category, cotinine concentration, and household earnings.

Results

After accounting for confounding factors, the findings indicated that for each incremental rise of 1 log unit in 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin, there was a 76% rise in the likelihood of death from any cause, with a p value of 0.003. An increase of 1 log unit in the concentration of 1,2,3,4,6,7,8-heptachlorodibenzofuran could potentially lead to a 90% higher risk of cancer mortality, as indicated by a p value of 0.034 and a 95% confidence interval of 0.05-2.43. As the concentrations of 1,2,3,4,6,7,8-heptachlorodibenzofuran increased, the dose-response curve indicated a proportional rise in the risk of cancer mortality, accompanied by a linear p value of 0.044. The sensitivity analysis demonstrated that our findings were resilient.

Discussion

In the general population, an elevated risk of cancer mortality was observed in PCDDs due to the presence of 1,2,3,4,6,7,8-heptachlorodibenzofuran. Mechanistic research is required to further confirm it.

Urinary Microbiome Dysbiosis and Immune Dysregulations as Potential Diagnostic Indicators of Bladder Cancer

There are a total of 82,290 new cases and 16,710 deaths estimated for bladder cancer in the United States in 2023. Currently, urine cytology tests are widely used for bladder cancer diagnosis, though they suffer from variable sensitivity, ranging from 45 to 97%. More recently, the microbiome has become increasingly recognized for its role in human diseases, including cancers. This study attempts to characterize urinary microbiome bladder cancer-specific dysbiosis to explore its diagnostic potential. RNA-sequencing data of urine samples from patients with bladder cancer (n = 18) and matched controls (n = 12) were mapped to bacterial sequences to yield species-level abundance approximations. Urine samples were analyzed at both the population and species level to reveal dysbiosis associated with bladder cancer. A panel of 35 differentially abundant species was discovered, which may be useful as urinary biomarkers for this disease. We further assessed whether these species were of similar significance in a validation dataset (n = 81), revealing that the genera Escherichia, Acinetobacter, and Enterobacter were consistently differentially abundant. We discovered distinct patterns of microbial-associated immune modulation in these samples. Several immune pathways were found to be significantly enriched with respect to the abundance of these species, including antigen processing and presentation, cytosolic DNA sensing, and leukocyte transendothelial migration. Differential cytokine activity was similarly observed, suggesting the urinary microbiome's correlation to immune modulation. The adherens junction and WNT signaling pathways, both implicated in the development and progression of bladder cancer, were also enriched with these species. Our findings indicate that the urinary microbiome may reflect both microbial and immune dysregulations of the tumor microenvironment in bladder cancer. Given the potential biomarker species identified, the urinary microbiome may provide a non-invasive, more sensitive, and more specific diagnostic tool, allowing for the earlier diagnosis of patients with bladder cancer.

Exposure to Agent Orange and Risk of Bladder Cancer Among US Veterans

Importance

To date, limited data exist regarding the association between Agent Orange and bladder cancer, and the Institute of Medicine concluded that the association between exposure to Agent Orange and bladder cancer outcomes is an area of needed research.

Objective

To examine the association between bladder cancer risk and exposure to Agent Orange among male Vietnam veterans.

Design, Setting, and Participants

This nationwide Veterans Affairs (VA) retrospective cohort study assesses the association between exposure to Agent Orange and bladder cancer risk among 2 517 926 male Vietnam veterans treated in the VA Health System nationwide from January 1, 2001, to December 31, 2019. Statistical analysis was performed from December 14, 2021, to May 3, 2023.

Exposure

Agent Orange.

Main Outcomes and Measures

Veterans exposed to Agent Orange were matched in a 1:3 ratio to unexposed veterans on age, race and ethnicity, military branch, and year of service entry. Risk of bladder cancer was measured by incidence. Aggressiveness of bladder cancer was measured by muscle-invasion status using natural language processing.

Results

Among the 2 517 926 male veterans (median age at VA entry, 60.0 years [IQR, 56.0-64.0 years]) who met inclusion criteria, there were 629 907 veterans (25.0%) with Agent Orange exposure and 1 888 019 matched veterans (75.0%) without Agent Orange exposure. Agent Orange exposure was associated with a significantly increased risk of bladder cancer, although the association was very slight (hazard ratio [HR], 1.04; 95% CI, 1.02-1.06). When stratified by median age at VA entry, Agent Orange was not associated with bladder cancer risk among veterans older than the median age but was associated with increased bladder cancer risk among veterans younger than the median age (HR, 1.07; 95% CI, 1.04-1.10). Among veterans with a diagnosis of bladder cancer, Agent Orange was associated with lower odds of muscle-invasive bladder cancer (odds ratio [OR], 0.91; 95% CI, 0.85-0.98).

Conclusions and Relevance

In this cohort study among male Vietnam veterans, there was a modestly increased risk of bladder cancer-but not aggressiveness of bladder cancer-among those exposed to Agent Orange. These findings suggest an association between Agent Orange exposure and bladder cancer, although the clinical relevance of this was unclear.

Cancer Screening Among Current and Former U.S. Military Personnel Compared to Civilians: A Cross-Sectional Analysis of the Behavioral Risk Factor Surveillance System

INTRODUCTION

Approximately 3% of invasive U.S. cancer diagnoses are made among veterans in a Veterans Affairs (VA) clinic each year, while VA patients only comprise about 1.9% of the U.S. population. Although some research has shown that veterans have higher incidence rates of cancer compared to civilians, evidence is sparse regarding possible disparities in rates of cancer screening between these populations. Thus, the purpose of this study is to compare differences in rates of screening for colorectal, lung, breast, and cervical cancers between current and former U.S. Military service members and civilians.

METHODS

Using the data extracted from the Behavioral Risk Factor Surveillance System, we assessed the rates of cancer screening among current and former U.S. Military service members compared to civilians from self-reported surveys assessing when individuals had been screened for colorectal or lung cancer among all participants and breast and cervical cancer among women participants. Persons greater than 25 years of age were included in the cervical cancer screening, 50 years of age for colon cancer screening, and 40 years of age for the breast cancer screening-the latter based on recommendations from the American Cancer Society. We used multivariate logistic regression models to determine the adjusted risk ratios (ARRs) of current and former U.S. Military service members receiving screening compared to civilians, adjusting for age, gender, race, education, and health care coverage.

RESULTS

Current and former U.S. Military service members accounted for 2.6% of individuals included for the cervical cancer screening analysis, 2.2% for the breast cancer screening analyses, nearly 10% of the lung cancer screening, and 15% of the colorectal cancer (CRC) screening analyses. Prevalence of screening was higher for current and former U.S. Military service members among lung cancer and CRC. When controlling for age, race, education, and health care coverage, current and former U.S. Military service members were statistically more likely to be screened for CRC (ARR: 1.05; 95% confidence interval: 1.04-1.07) and lung cancer (ARR: 1.32; 95% confidence interval: 1.15-1.52). The odds of having completed a cervical or breast cancer screening were not significantly different between groups.

CONCLUSION

Our study showed that current and former U.S. Military service members were more likely to complete CRC and lung cancer screenings, while no significant difference existed between each population with regard to cervical and breast cancer screenings. This is one of the few studies that have directly compared cancer screening usage among civilians and current and former U.S. Military service members. Although current and former U.S. Military service members were more likely to receive several cancer screenings, improvements can still be made to remove barriers and increase screening usage due to the disproportionate rates of cancer mortality in this population. These solutions should be comprehensive-addressing personal, organizational, and societal barriers-to improve prognosis and survival rates among current and former U.S. Military service members.

The Epidemiology of Bladder Cancer

There are many risk factors for bladder cancer. During an initial assessment of a patient with bladder cancer, a careful discussion and history assessment is important. Particular focus should include social history with details regarding occupational background and discussion of any environmental exposure history.