Neighbourhood socioeconomic status and individual lung cancer risk: Evaluating long-term exposure measures and mediating mechanisms

The Association of Context with Reported Self-Efficacy for Cancer-Preventive Behaviors and Perceived Cancer Risk in U.S. Adults from the Midlife in the United States (MIDUS) Study

Background: Cancer is one of the leading causes of death in the United States. It is critical to understand the associations among multilevel determinants of cancer prevention and control behaviors. This study examined associations of neighborhood factors with perceived risk of cancer and self-efficacy for reducing cancer risk. Methods: Cross-sectional analyses included 2324 U.S. adults from the Midlife in the U.S. Wave 3. Participants completed surveys of neighborhood environment (perceived neighborhood trust and safety, built environment conditions, social integration), perceived cancer risk and cancer prevention efficacy. Multivariate linear regressions examined associations of neighborhood context with risk perceptions and self-efficacy. Results: In the model that adjusted for sociodemographic characteristics, better perceived neighborhood trust and safety were associated with lower perceived cancer risk. In fully adjusted models for sociodemographic characteristics and contextual factors, higher perceptions of neighborhood trust and safety were associated with higher cancer prevention self-efficacy. Perceptions of better built neighborhood conditions and higher social integration were significantly associated with lower perceived cancer risk and higher perceived cancer prevention efficacy. Conclusions: Perceptions of neighborhood context may play a role in shaping psychosocial factors such as perceived cancer risk and self-efficacy, even after controlling for robust predictors of these perceptions.

Addressing Inequity in Spatial Access to Lung Cancer Screening

BACKGROUND

The successful implementation of an equitable lung cancer screening program requires consideration of factors that influence accessibility to screening services.

METHODS

Using lung cancer cases in British Columbia (BC), Canada, as a proxy for a screen-eligible population, spatial access to 36 screening sites was examined using geospatial mapping and vehicle travel time from residential postal code at diagnosis to the nearest site. The impact of urbanization and Statistics Canada's Canadian Index of Multiple Deprivation were examined.

RESULTS

Median travel time to the nearest screening site was 11.7 min (interquartile range 6.2-23.2 min). Urbanization was significantly associated with shorter drive time (p < 0.001). Ninety-nine percent of patients with ≥60 min drive times lived in rural areas. Drive times were associated with sex, ethnocultural composition, situational vulnerability, economic dependency, and residential instability. For example, the percentage of cases with drive times ≥60 min among the least deprived situational vulnerability group was 4.7% versus 44.4% in the most deprived group.

CONCLUSIONS

Populations at risk in rural and remote regions may face more challenges accessing screening services due to increased travel times. Drive times increased with increasing sociodemographic and economic deprivations highlighting groups that may require support to ensure equitable access to lung cancer screening.

Polysomnographic Assessment of Sleep Disturbances in Cancer Development: A Historical Multicenter Clinical Cohort Study

BACKGROUND

Many cellular processes are controlled by sleep. Therefore, alterations in sleep might be expected to stress biological systems that could influence malignancy risk.

RESEARCH QUESTION

What is the association between polysomnographic measures of sleep disturbances and incident cancer, and what is the validity of cluster analysis in identifying polysomnography phenotypes?

STUDY DESIGN AND METHODS

We conducted a retrospective multicenter cohort study using linked clinical and provincial health administrative data on consecutive adults free of cancer at baseline with polysomnography data collected between 1994 and 2017 in four academic hospitals in Ontario, Canada. Cancer status was derived from registry records. Polysomnography phenotypes were identified by k-means cluster analysis. A combination of validation statistics and distinguishing polysomnographic features was used to select clusters. Cox cause-specific regressions were used to assess the relationship between identified clusters and incident cancer.

RESULTS

Among 29,907 individuals, 2,514 (8.4%) received a diagnosis of cancer over a median of 8.0 years (interquartile range, 4.2-13.5 years). Five clusters were identified: mild (mildly abnormal polysomnography findings), poor sleep, severe OSA or sleep fragmentation, severe desaturations, and periodic limb movements of sleep (PLMS). The associations between cancer and all clusters compared with the mild cluster were significant while controlling for clinic and year of polysomnography. When additionally controlling for age and sex, the effect remained significant only for PLMS (adjusted hazard ratio [aHR], 1.26; 95% CI, 1.06-1.50) and severe desaturations (aHR, 1.32; 95% CI, 1.04-1.66). Further controlling for confounders, the effect remained significant for PLMS, but was attenuated for severe desaturations.

INTERPRETATION

In a large cohort, we confirmed the importance of polysomnographic phenotypes and highlighted the role that PLMS and oxygenation desaturation may play in cancer. Using this study's findings, we also developed an Excel (Microsoft) spreadsheet (polysomnography cluster classifier) that can be used to validate the identified clusters on new data or to identify which cluster a patient belongs to.

TRIAL REGISTRY

ClinicalTrials.gov; Nos.: NCT03383354 and NCT03834792; URL: www.

CLINICALTRIALS

gov.

Surgical Treatment at an Academic Medical Center is Associated with Statistically Insignificant Lung Cancer Survival Outcome Differences Related to ZIP Code

BACKGROUND

Low socioeconomic status is a well-characterized adverse prognostic factor in large lung cancer databases. However, such characterizations may be confounded as patients of lower socioeconomic status are more often treated at low-volume, non-academic centers. We evaluated whether socioeconomic status, as defined by ZIP code median income, was associated with differences in lung cancer resection outcomes within a high-volume academic medical center.

METHODS

Consecutive patients undergoing resection for non-small cell lung cancer were identified from a prospectively maintained database (2011-18). Patients were assigned an income value based on the median income of their ZIP code as determined by census-based geographic data. We stratified the population into income quintiles representative of SES and compared demographics (chi-square), surgical outcomes, and survival (Kaplan-Meier).

RESULTS

We identified 1,693 patients, representing 516 ZIP codes. Income quintiles were Q1: $24,421-53,151; Q2:$53,152-73,982; Q3:$73,983-99,063; Q4:$99,064-123,842; and Q5:$123,843-250,001. Compared to Q5 patients, Q1 patients were younger (median 69 vs. 73, p < 0.001), more likely male (44 vs. 36%, p = 0.035), and more likely Asian, Black, or self-identified as other than white, Asian, or Black. (67 vs. 11%, p =  < 0.001). We found minor differences in surgical outcomes and no significant difference in 5-year survival between Q1 and Q5 patients (5-year: 86 vs. 85%, p = 0.886).

CONCLUSIONS

Surgical care patterns at a high-volume academic medical center are similar among patients from varying ZIP codes. Surgical treatment at such a center is associated with no survival differences based upon socioeconomic status as determined by ZIP code. Centralization of lung cancer surgical care to high-volume centers may reduce socioeconomic outcome disparities.

Small area disease mapping of cancer incidence in British Columbia using Bayesian spatial models and the smallareamapp R Package

INTRODUCTION

There is an increasing interest in small area analyses in cancer surveillance; however, technical capacity is limited and accessible analytical approaches remain to be determined. This study demonstrates an accessible approach for small area cancer risk estimation using Bayesian hierarchical models and data visualization through the smallareamapp R package.

MATERIALS AND METHODS

Incident lung (N = 26,448), female breast (N = 28,466), cervical (N = 1,478), and colorectal (N = 25,457) cancers diagnosed among British Columbia (BC) residents between 2011 and 2018 were obtained from the BC Cancer Registry. Indirect age-standardization was used to derive age-adjusted expected counts and standardized incidence ratios (SIRs) relative to provincial rates. Moran's I was used to assess the strength and direction of spatial autocorrelation. A modified Besag, York and Mollie model (BYM2) was used for model incidence counts to calculate posterior median relative risks (RR) by Community Health Service Areas (CHSA; N = 218), adjusting for spatial dependencies. Integrated Nested Laplace Approximation (INLA) was used for Bayesian model implementation. Areas with exceedance probabilities (above a threshold RR = 1.1) greater or equal to 80% were considered to have an elevated risk. The posterior median and 95% credible intervals (CrI) for the spatially structured effect were reported. Predictive posterior checks were conducted through predictive integral transformation values and observed versus fitted values.

RESULTS

The proportion of variance in the RR explained by a spatial effect ranged from 4.4% (male colorectal) to 19.2% (female breast). Lung cancer showed the greatest number of CHSAs with elevated risk (Nwomen = 50/218, Nmen = 44/218), representing 2357 total excess cases. The largest lung cancer RRs were 1.67 (95% CrI = 1.06-2.50; exceedance probability = 96%; cases = 13) among women and 2.49 (95% CrI = 2.14-2.88; exceedance probability = 100%; cases = 174) among men. Areas with small population sizes and extreme SIRs were generally smoothed towards the null (RR = 1.0).

DISCUSSION

We present a ready-to-use approach for small area cancer risk estimation and disease mapping using BYM2 and exceedance probabilities. We developed the smallareamapp R package, which provides a user-friendly interface through an R-Shiny application, for epidemiologists and surveillance experts to examine geographic variation in risk. These methods and tools can be used to estimate risk, generate hypotheses, and examine ecologic associations while adjusting for spatial dependency.

Neighborhood disadvantage and lung cancer risk in a national cohort of never smoking Black women

BACKGROUND

Compared to women of other races who have never smoked, Black women have a higher risk of lung cancer. Whether neighborhood disadvantage, which Black women experience at higher rates than other women, is linked to never-smoking lung cancer risk remains unclear. This study investigates the association of neighborhood disadvantage and lung cancer risk in Black never-smoking women.

METHODS AND MATERIALS

This research utilized data from the Black Women's Health Study, a prospective cohort of 59,000 Black women recruited from across the US in 1995 and followed by biennial questionnaires. Associations of lung cancer incidence with neighborhood-level factors (including two composite variables derived from Census Bureau data: neighborhood socioeconomic status and neighborhood concentrated disadvantage), secondhand smoke exposure, and PM_2.5 were estimated using Fine-Gray subdistribution hazard models.

RESULTS

Among 37,650 never-smokers, 77 were diagnosed with lung cancer during follow-up from 1995 to 2018. The adjusted subdistribution hazard ratio (sHR) of lung cancer incidence with ten unit increase in neighborhood concentrated disadvantage index was 1.30 (95 % CI: 1.04, 1.63, p = 0.023). Exposure to secondhand smoke at work was associated with increased risk (sHR = 1.93, 95 % CI: 1.21, 3.10, p = 0.006), but exposure to secondhand smoke at home and PM_2.5 was not.

CONCLUSION

Worse neighborhood concentrated disadvantage was associated with increased lung cancer risk in Black women who never smoked. These findings suggest that non-tobacco-related factors in disadvantaged neighborhoods may be linked to lung cancer risk in Black women and that these factors must be understood and targeted to achieve health equity.

Exposure to urban greenspace and pathways to respiratory health: An exploratory systematic review

BACKGROUND/OBJECTIVE

Urban greenspace may have a beneficial or adverse effect on respiratory health. Our objective was to perform an exploratory systematic review to synthesise the evidence and identify the potential causal pathways relating urban greenspace and respiratory health.

METHODS

We followed PRISMA guidelines on systematic reviews and searched five databases for eligible studies during 2000-2021. We incorporated a broad range of urban greenspace and respiratory health search terms, including both observational and experimental studies. Screening, data extraction, and risk of bias, assessed using the Navigation Guide criteria, were performed independently by two authors. We performed a narrative synthesis and discuss suggested pathways to respiratory health.

RESULTS

We identified 108 eligible papers (n = 104 observational, n = 4 experimental). The most common greenspace indicators were the overall greenery or vegetation (also known as greenness), green land use/land cover of physical area classes (e.g., parks, forests), and tree canopy cover. A wide range of respiratory health indicators were studied, with asthma prevalence being the most common. Two thirds (n = 195) of the associations in these studies were positive (i.e., beneficial) with health, with 31% (n = 91) statistically significant; only 9% (n = 25) of reported associations were negative (i.e., adverse) with health and statistically significant. The most consistent positive evidence was apparent for respiratory mortality. There were n = 35 (32%) 'probably low' and n = 73 (68%) 'probably high' overall ratings of bias. Hypothesised causal pathways for health benefits included lower air pollution, more physically active populations, and exposure to microbial diversity; suggested mechanisms with poorer health included exposure to pollen and other aeroallergens.

CONCLUSION

Many studies showed positive association between urban greenspace and respiratory health, especially lower respiratory mortality; this is suggestive, but not conclusive, of causal effects. Results underscore the importance of contextual factors, greenspace metric employed, and the potential bias of subtle selection factors, which should be explored further.

Socioeconomic status and risk of lung cancer by histological subtype in the Nordic countries

BACKGROUND

While the excess in lung cancer risk among lower socioeconomic status individuals has been widely described, the magnitude of this association across lung cancer subtypes, as well as histotype-related long-term incidence trends, are inconclusively reported.

AIMS

We explored the variation in the incidence of the three main lung cancer histotypes (i.e. squamous cell carcinoma, small cell carcinoma and adenocarcinoma) by socioeconomic status (SES, i.e. upper and lower white collar, upper and lower blue collar, and farming/forestry/fishing) in the adult population of four Nordic countries (i.e. Sweden, Norway, Finland and Denmark).

MATERIALS & METHODS

We have used data from the Nordic Occupational Cancer Study (NOCCA), computing age-standardized incidence rates per 100,000 person-years truncated at ages 50-69 years, by sex, histotype, country and SES, for the period 1971-2005. We estimated relative risks and the corresponding 95% confidence intervals through Poisson regression models, including terms for SES, age, sex and country, as indicated.

RESULTS

A clear socioeconomic gradient, with a progressive increase in lung cancer risk as SES level decreases, was observed in all subtypes and in both sexes. Favourable lung cancer incidence trends were seen among men for squamous cell and small cell carcinomas, although for adenocarcinomas rates were increasing everywhere except for Finland. Among women, upward temporal trends were seen in all SES groups and for all subtypes, although rates increased to a greater extent for low, compared to high, SES, especially in Denmark and Norway. Farmers showed comparatively lower risks compared to other SES categories.

DISCUSSION

This prospective cohort study shows that substantial socioeconomic inequalities in the incidence of the most important lung cancer histotypes exist in the Nordic Countries, and that these inequalities are on the rise, especially among women.

CONCLUSION

Smoking habits are likely to largely explain the observed social gradient for lung cancer histotypes in both sexes.

Neighborhood Socioeconomic Deprivation in Young Adulthood and Future Respiratory Health: The CARDIA Lung Study

PURPOSE

There are limited data on the relationship between neighborhood level factors and their association with lung health independent of individual socioeconomic status. We sought to determine whether baseline neighborhood level socioeconomic deprivation in young adults is associated with greater 20-year decline in lung function and higher risk of future lung disease, independent of baseline individual income, education, and smoking status.

METHODS

This multicenter population-based cohort study included 2689 participants in Coronary Artery Risk Development in Young Adults (CARDIA) for whom neighborhood deprivation was determined at year 10 (baseline for study) and who had complete lung function measurements at years 10 and 30. Baseline neighborhood deprivation was defined using 1990 Census blocks as a combination of 4 factors involving median household income, poverty level, and educational achievement. The outcomes were decline in lung function over 20 years (year 10 to 30) and odds of emphysema (year 25).

RESULTS

In multivariable regression models, greater baseline neighborhood deprivation was associated with greater decline in lung function (-2.34 mL/year excess annual decline in forced expiratory volume in 1 second (FEV₁) in the highest versus lowest deprivation quartile (P = .014)). Furthermore, baseline neighborhood deprivation was independently associated with greater odds of emphysema (odds ratio [OR] 2.99, 95% confidence interval [CI] 1.42-6.30).

CONCLUSIONS

Residence in neighborhoods with greater socioeconomic deprivation in young adulthood, independent of individual income and smoking, is associated with greater 20-year decline in forced expiratory volume in 1 second and higher risk of future emphysema.

The Social and Natural Environment's Impact on SARS-CoV-2 Infections in the UK Biobank

COVID-19 has caused a global pandemic with considerable impact. Studies have examined the influence of socioeconomic status and air pollution on COVID-19 risk but in low detail. This study seeks to further elucidate the nuances of socioeconomic status, as defined by the Index of Multiple Deprivation (IMD), air pollution, and their relationship. We examined the effect of IMD and air pollution on the likelihood of testing positive for SARS-CoV-2 among 66,732 UKB participants tested for SARS-CoV-2 from 16 March 2020 through 16 March 2021. Logistic regression was performed controlling for age, sex, ancestry and IMD or air pollution in the respective models. IMD and its sub-scores were significantly associated with increased risk of testing positive for SARS-CoV-2. All particulate matter less than 2.5 μm (PM2.5), nitrogen oxide (NO_x), and nitrogen dioxide (NO₂) levels were associated with increased likelihood of testing positive for SARS-CoV-2. Measures of green space and natural environment around participants' homes were associated with reduced likelihood of SARS-CoV-2. Socioeconomic status and air pollution have independent effects on the risk of testing positive for SARS-CoV-2. Green space and natural environment space in the proximity of people's homes may mediate the effect of air pollution on the risk of testing positive for SARS-CoV-2.

Polysomnographic Markers of Obstructive Sleep Apnea Severity and Cancer-Related Mortality: A Large Retrospective Multicenter Clinical Cohort Study

RATIONALE

The evidence for an association between cancer survival and obstructive sleep apnea (OSA) remains under-explored.

OBJECTIVES

To evaluate an association between markers of OSA severity (respiratory disturbances, hypoxemia, and sleep fragmentation) and cancer-related mortality in individuals with previously diagnosed cancer.

METHODS

We conducted a multicenter retrospective cohort study using linked clinical and provincial health administrative data on consecutive adults who underwent a diagnostic sleep study between 1994 and 2017 in four Canadian academic hospitals and were previously diagnosed with cancer through the Ontario Cancer Registry. Multivariable cause-specific Cox regressions were utilized to address the research objective.

RESULTS

We included 2,222 subjects. Over a median follow-up time of 5.6 years (IQR: 2.7-9.1), 261/2,222 (11.7%) individuals with prevalent cancer died from cancer-related causes, which accounted for 44.2% (261/590) of all-cause death. Controlling for age, sex, alcohol use disorder, prior heart failure, COPD, hypertension, diabetes, treatment for OSA, clinic site, year of the sleep study, and time since the cancer diagnosis, measures of hypoxemia and sleep fragmentation, but not apnea-hypopnea index were significantly associated with the cancer-specific mortality: % time spent with SaO2 <90% (HR per 5% increase: 1.05; 95% CI: 1.01-1.09); mean SaO2 (HR per 3% increase: 0.79; 0.68-0.92); and % of Stage 1 Sleep (HR per 16% increase: 1.27; 1.07-1.51).

CONCLUSION

In a large clinical cohort of adults with suspected OSA and previously diagnosed cancer, measures of nocturnal hypoxemia and sleep fragmentation as markers of OSA severity were significantly associated with cancer-related mortality, suggesting the need for more targeted risk awareness.

Health-Promoting Behaviors of Low-Income Adults in a Community Health Center

Health-promoting behaviors improve health, prevent disease, and decrease healthcare costs. This study describes the health-promotion behaviors and identifies influencing factors of health-promoting behaviors in low-income patients at a community health center. This cross-sectional study used participants from a center serving a low-income population. Spiritual growth and interpersonal relations were the two most practiced health-promoting behaviors. Age and education influenced participation in health-promoting behaviors. Promoting spiritual growth and interpersonal relations is a critical part of supporting health-promoting behaviors. Findings provide guidance for nurses to contribute to increasing healthy behaviors and develop interventions to improve participation in health-promoting behaviors.

Complete physical examinations in Manitoba adults with an intellectual or developmental disability: A retrospective cohort study

BACKGROUND

Complete physical examinations (CPE) can identify health disparities in persons with intellectual or developmental disabilities. The objective of this study was to determine and compare rates of CPE among Manitoba adults with and without intellectual or developmental disabilities over time and to identify factors that were associated with receiving a CPE.

METHOD

A retrospective cohort study using linked administrative health and non-health data from 1995 to 2015 was conducted. Poisson and logistic regression were used to calculate CPE rates and examine factors associated with CPE.

RESULTS

The rates of CPE are decreasing over time and are higher among Manitobans with an intellectual or developmental disability. Characteristics such as being male, living rurally, low socioeconomic status, and high continuity of care led to lower odds of receiving a CPE.

CONCLUSIONS

The current state of CPE provision to adults with intellectual or developmental disabilities in Manitoba is encouraging but needs improvement.

Obstructive Sleep Apnea and Incident Cancer: A Large Retrospective Multicenter Clinical Cohort Study

BACKGROUND

To examine the association between the severity of obstructive sleep apnea (OSA) and nocturnal hypoxemia with incident cancer.

METHODS

This was a multicenter retrospective clinical cohort study using linked clinical and provincial health administrative data on consecutive adults who underwent a diagnostic sleep study between 1994 and 2017 in four academic hospitals (Canada) who were free of cancer at baseline. Cancer status was derived from the Ontario Cancer Registry. Cox cause-specific regressions were utilized to address the objective and to calculate the 10-year absolute risk difference (ARD) in the marginal probability of incident cancer and the number needed to harm (NNH).

RESULTS

Of 33,997 individuals considered, 33,711 with no missing OSA severity were included: median age, 50 years; 58% male; and 23% with severe OSA (apnea-hypopnea index >30). Of the 18,458 individuals with information on sleep time spent with oxygen saturation (SaO₂) <90%, 5% spent >30% of sleep with SaO₂ <90% (severe nocturnal hypoxemia). Over a median of 7 years, 2,498 of 33,711 (7%) individuals developed cancer, with an incidence rate of 10.3 (10.0-10.8) per 1,000 person-years. Controlling for confounders, severe OSA was associated with a 15% increased hazard of developing cancer compared with no OSA (HR = 1.15, 1.02-1.30; ARD = 1.28%, 0.20-2.37; and NNH = 78). Severe hypoxemia was associated with about 30% increased hazard (HR = 1.32, 1.08-1.61; ARD = 2.38%, 0.47-4.31; and NNH = 42).

CONCLUSIONS

In a large cohort of individuals with suspected OSA free of cancer at baseline, the severity of OSA and nocturnal hypoxemia was independently associated with incident cancer.

IMPACT

These findings suggest the need for more targeted cancer risk awareness in individuals with OSA.

Augmenting disease maps: a Bayesian meta-analysis approach

Analysis of spatial patterns of disease is a significant field of research. However, access to unit-level disease data can be difficult for privacy and other reasons. As a consequence, estimates of interest are often published at the small area level as disease maps. This motivates the development of methods for analysis of these ecological estimates directly. Such analyses can widen the scope of research by drawing more insights from published disease maps or atlases. The present study proposes a hierarchical Bayesian meta-analysis model that analyses the point and interval estimates from an online atlas. The proposed model is illustrated by modelling the published cancer incidence estimates available as part of the online Australian Cancer Atlas (ACA). The proposed model aims to reveal patterns of cancer incidence for the 20 cancers included in ACA in major cities, regional and remote areas. The model results are validated using the observed areal data created from unit-level data on cancer incidence in each of 2148 small areas. It is found that the meta-analysis models can generate similar patterns of cancer incidence based on urban/rural status of small areas compared with those already known or revealed by the analysis of observed data. The proposed approach can be generalized to other online disease maps and atlases.

Current State of Geospatial Methodologic Approaches in Canadian Population Oncology Research

Geospatial analyses are increasingly used in population oncology. We provide a first review of geospatial analysis in Canadian population oncology research, compare to international peers, and identify future directions. Geospatial-focused peer-reviewed publications from 1992-2020 were compiled using PubMed, MEDLINE, Web of Science, and Google Scholar. Abstracts were screened for data derived from a Canadian cancer registry and use of geographic information systems. Studies were classified by geospatial methodology, geospatial unit, location, cancer site, and study year. Common limitations were documented from article discussion sections. Our search identified 71 publications using data from all provincial and national cancer registries. Thirty-nine percent (N = 28) were published in the most recent 5-year period (2016-2020). Geospatial methodologies included exposure assessment (32.4%), identifying spatial associations (21.1%), proximity analysis (16.9%), cluster detection (15.5%), and descriptive mapping (14.1%). Common limitations included confounding, ecologic fallacy, not accounting for residential mobility, and small case/population sizes. Geospatial analyses are increasingly used in Canadian population oncology; however, efforts are concentrated among a few provinces and common cancer sites, and data are over a decade old. Limitations were similar to those documented internationally, and more work is needed to address them. Organized efforts are needed to identify common challenges, develop leading practices, and identify shared priorities.

Neighborhood Disadvantage and Lung Cancer Incidence in Ever-Smokers at a Safety Net Health-Care System: A Retrospective Study

BACKGROUND

Neighborhood circumstances have an influence on multiple health outcomes, but the association between neighborhood conditions and lung cancer incidence has not been studied in sufficient detail. The goal of this study was to understand whether neighborhood conditions are independently associated with lung cancer incidence in ever-smokers after adjusting for individual smoking exposure and other risk factors.

METHODS

A cohort of ever-smokers aged ≥ 55 years was assembled from 19 years of electronic health record data from our academic community health-care system. Patient demographic characteristics and other measures known to be associated with lung cancer were ascertained. Patient addresses at their index visit were geocoded to the census block group level to determine the area deprivation index (ADI), drawn from 5-year estimates from the American Community Survey. A multivariate Cox proportional hazards model was fit to assess the association between ADI and time to lung cancer diagnosis. Tests of statistical significance were two-sided.

RESULTS

The study included 19,867 male subjects and 21,748 female subjects. Fifty-three percent of the patients were white, 38% were black, and 5% were Hispanic. Of these, 1,149 developed lung cancer. After adjusting for known risk factors, patients residing in the most disadvantaged areas had a significantly increased incidence of lung cancer compared with those in the least disadvantaged areas (hazard ratio, 1.29; 95% CI 1.07-1.55).

CONCLUSIONS

Census-derived estimates of neighborhood conditions have a powerful association with lung cancer incidence, even when adjusting for individual variables. Further research investigating the mechanisms that link neighborhood conditions to lung cancer is warranted.

Neighbourhood-level deprivation indices and postpartum women's health: results from the Community Child Health Network (CCHN) multi-site study

Background

Area-level socioeconomic characteristics have been shown to be related to health status and mortality however, little is known about the association between residential community characteristics in relation to postpartum women’s health.

Methods

Data from the longitudinal, multi-site Community Child Health Network (CCHN) study were used. Postpartum women (n = 2510), aged 18–40 were recruited from 2008 to 2012 within a month of delivery. Socioeconomic data was used to create deprivation indices. Census data were analysed using principal components analysis (PCA) and logistic regression to assess the association between deprivation indices (DIs) and various health indicators.

Results

PCA resulted in two unique DIs that accounted for 67.5% of the total variance of the combined all-site area deprivation. The first DI was comprised of variables representing a high percentage of Hispanic or Latina, foreign-born individuals, dense households (more than one person per room of residence), with less than a high-school education, and who spent more than 30% of their income on housing costs. The second DI was comprised of a high percentage of African-Americans, single mothers, and high levels of unemployment. In a multivariate logistic regression model, using the quartiles of each DI, women who reside in the geographic area of Q4-Q2 of the second DI, were almost twice as likely to have more than three adverse health conditions compared to those who resided in the least deprived areas. (Q2vs.Q1:OR = 2.09,P = 0.001,Q3vs.Q1:OR = 1.89,P = 0.006,Q4vs.Q1:OR = 1.95,P = 0.004 respectively).

Conclusions

Our results support the utility of examining deprivation indices as predictors of maternal postpartum health.

The respective parts of incidence and lethality in socioeconomic differences in cancer mortality. An analysis of the French network Cancer registries (FRANCIM) data

Background

To determine relevant public health actions and to guide intervention priorities, it is of great importance to assess the relative contribution of incidence and lethality to social inequalities in cancer mortality.

Methods

The study population comprised 185,518 cases of cancer diagnosed between 2006 and 2009 recorded in the French registries. Survival was known for each patient (endpoint: 30/06/2013). Deprivation was assessed using the European Deprivation Index. We studied the influence of deprivation on mortality, incidence and lethality rates and quantified the respective proportions of incidence and lethality in social inequalities in mortality by calculating attributable deaths.

Results

For cancers with social inequalities both in incidence and lethality, excess mortality in deprived was mainly caused by social inequalities in incidence (e.g. men lung cancer: 87% of excess deaths in the deprived caused by inequalities in incidence). Proportions were more balanced for some cancer sites (e.g. cervical cancer: 56% incidence, 44% lethality). For cancer sites with a higher incidence in the least deprived (e.g. breast cancer), the excess-lethality in deprived leads entirely the higher mortality among the deprived.

Conclusions

Most of the excess mortality in deprived is due to the excess incidence of tobacco-dependent cancers and the excess lethality of screenable cancers.

Is cancer prevention influenced by the built environment? A multidisciplinary scoping review

The built environment is a significant determinant of human health. Globally, the growing prevalence of preventable cancers suggests a need to understand how features of the built environment shape exposure to cancer development and distribution within a population. This scoping review examines how researchers across disparate fields understand and discuss the built environment in primary and secondary cancer prevention. It is focused exclusively on peer-reviewed sources published from research conducted in Australia, Canada, Ireland, New Zealand, the United Kingdom, and the United States from 1990 to 2017. The review captured 9958 potential results in the academic literature, and this body of results was scoped to 268 relevant peer-reviewed journal articles indexed across 13 subject databases. Spatial proximity, transportation, land use, and housing are well-understood features of the built environment that shape cancer risk. Built-environment features predominantly influence air quality, substance use, diet, physical activity, and screening adherence, with impacts on breast cancer, lung cancer, colorectal cancer, and overall cancer risk. The majority of the evidence fails to provide direct recommendations for advancing cancer prevention policy and program objectives for municipalities. The expansion of interdisciplinary work in this area would serve to create a significant population health impact.

Risks and burden of lung cancer incidence for residential petrochemical industrial complexes: A meta-analysis and application

BACKGROUND

Lung cancer is one of the most common cancers in the world. Higher incidence of lung cancer may be associated with residential proximity to a petrochemical industrial complex (PIC) due to exposure to various carcinogens, although results from previous epidemiologic studies remain inconclusive. Because disease burden due to residential inequality is a public health and societal concern, this study analyzed published data to estimate lung cancer incidence in association with residential proximity to PICs.

METHODS

We performed a meta-analysis on selected epidemiologic studies that met the following criteria: lung cancer incidence was coded by the International Classification of Diseases; exposure groups were clearly defined as residents living near PICs; and confidence intervals were available or calculable from original articles. We further applied a population attributable factor (PAF) method to estimate disease burden attributable to living near PICs in 22 European Union (EU) countries.

RESULTS

Meta-analysis included six studies with a total of 466,066 residents living near PICs in six countries. Residents living near PICs had a 19% higher risk of lung cancer compared to those who lived farther away (95% CI = 1.06-1.32). By sex, risks were higher and more significant for females (RR = 1.29; 95% CI = 1.09-1.54; P = 0.004) than males (RR = 1.12; 95% CI = 0.95-1.33; P = 0.173). By location, only groups in Europe had a significantly greater risk of lung cancer with exposure to PICs (95% CI = 1.03-1.33; P = 0.019), although groups in other locations showed similar trends. By bona fide observation, observation of residents for at least seven years provided sufficient latency to estimate risk (RR = 1.25; 95% CI = 1.17-1.34; P < 0.001). Regarding burden of lung cancer in 22 EU countries, 494 males and 478 females were attributed to living in the vicinity of a PIC annually.

CONCLUSIONS

Lung cancer incidence is significantly higher in individuals living near PICs. This result provides strong epidemiologic evidence for further policy to regulate potential pollutants near PICs.

HIGHLIGHTS

Higher incident rates of lung cancer for residents living close to petrochemical industry complex.

Neighbourhood deprivation and lung cancer risk: a nested case-control study in the USA

OBJECTIVES

To examine the association between neighbourhood deprivation and lung cancer risk.

DESIGN

Nested case-control study.

SETTING

Southern Community Cohort Study of persons residing in 12 states in the southeastern USA.

PARTICIPANTS

1334 cases of lung cancer and 5315 controls.

PRIMARY OUTCOME MEASURE

Risk of lung cancer.

RESULTS

After adjustment for smoking status and other confounders, and additional adjustment for individual-level measures of socioeconomic status (SES), there was no monotonic increase in risk with worsening deprivation score overall or within sex and race groups. There was an increase among current and shorter term former smokers (p=0.04) but not among never and longer term former smokers. There was evidence of statistically significant interaction by sex among whites, but not blacks, in which the effect of worsening deprivation on lung cancer existed in males but not in females.

CONCLUSIONS

Area-level measures of SES were associated with lung cancer risk in current and shorter term former smokers only in this population.

Multiple mediators approach to study environmental chemicals as determinants of health disparities

A major goal of health disparities research is to identify and intervene upon modifiable risk factors that help explain the observed associations between social factors and adverse health outcomes. To this end, statistical methods incorporating mediation analysis have shown promise, as they quantify the contribution of an intermediate variable in an exposure-outcome association. A growing body of literature suggests that environmental chemicals can contribute to health disparities. However, evaluating environmental chemicals as an important component of health disparities introduces methodological complexities that may make standard mediation approaches inadequate. Specific to environmental health is the issue of evaluating both the source and biomarker of the environmental toxicant in order to calculate the proportion of the disparity that would remain had we intervened on the modifiable factors. Recent methodological developments on multiple mediators can improve efforts to integrate both source and biomarker of exposure into epidemiological studies of health disparities. We illustrate a conceptual framework and present how mediation techniques can be used to address environmental health disparities questions. With this, we provide a methodological tool that has the potential to advance this growing field, while simultaneously informing public health prevention and policy surrounding the impact of environmental factors on health disparities.

Lung cancer and socioeconomic status in a pooled analysis of case-control studies

BACKGROUND

An association between low socioeconomic status (SES) and lung cancer has been observed in several studies, but often without adequate control for smoking behavior. We studied the association between lung cancer and occupationally derived SES, using data from the international pooled SYNERGY study.

METHODS

Twelve case-control studies from Europe and Canada were included in the analysis. Based on occupational histories of study participants we measured SES using the International Socio-Economic Index of Occupational Status (ISEI) and the European Socio-economic Classification (ESeC). We divided the ISEI range into categories, using various criteria. Stratifying by gender, we calculated odds ratios (OR) and 95% confidence intervals (CI) by unconditional logistic regression, adjusting for age, study, and smoking behavior. We conducted analyses by histological subtypes of lung cancer and subgroup analyses by study region, birth cohort, education and occupational exposure to known lung carcinogens.

RESULTS

The analysis dataset included 17,021 cases and 20,885 controls. There was a strong elevated OR between lung cancer and low SES, which was attenuated substantially after adjustment for smoking, however a social gradient persisted. SES differences in lung cancer risk were higher among men (lowest vs. highest SES category: ISEI OR 1.84 (95% CI 1.61-2.09); ESeC OR 1.53 (95% CI 1.44-1.63)), than among women (lowest vs. highest SES category: ISEI OR 1.54 (95% CI 1.20-1.98); ESeC OR 1.34 (95% CI 1.19-1.52)).

CONCLUSION

SES remained a risk factor for lung cancer after adjustment for smoking behavior.

Lung cancer mortality of residents living near petrochemical industrial complexes: a meta-analysis

BACKGROUND

Lung cancer, as the leading cause of cancer mortality worldwide, has been linked to environmental factors, such as air pollution. Residential exposure to petrochemicals is considered a possible cause of lung cancer for the nearby population, but results are inconsistent across previous studies. Therefore, we performed a meta-analysis to estimate the pooled risk and to identify possible factors leading to the heterogeneity among studies.

METHODS

The standard process of selecting studies followed the Cochrane meta-analysis guideline of identification, screening, eligibility, and inclusion. We assessed the quality of selected studies using the Newcastle-Ottawa scale. Reported point estimates and 95% confidence intervals were extracted or calculated to estimate the pooled risk. Air quality standards were summarized and treated as a surrogate of exposure to air pollution in the studied countries. Funnel plots, Begg's test and Egger's test were conducted to diagnose publication bias. Meta-regressions were performed to identify explanatory variables of heterogeneity across studies.

RESULTS

A total of 2,017,365 people living nearby petrochemical industrial complexes (PICs) from 13 independent studied population were included in the analysis. The pooled risk of lung cancer mortality for residents living nearby PICs was 1.03-fold higher than people living in non-PIC areas (95% CI = 0.98-1.09), with a low heterogeneity among studies (I ²  = 25.3%). Such effect was stronger by a factor of 12.6% for the year of follow-up started 1 year earlier (p-value = 0.034).

CONCLUSIONS

Our meta-analysis gathering current evidence suggests only a slightly higher risk of lung cancer mortality among residents living nearby PICs, albeit such association didn't receive statistically significance. Reasons for higher risks of early residential exposure to PICs might be attributable to the lack of or less stringent air pollution regulations.

Effect of socioeconomic status on stage at diagnosis of lung cancer in a hospital-based multicenter retrospective clinical epidemiological study in China, 2005-2014

There is inconsistent evidence of associations between socioeconomic status (SES) and lung cancer stage in non‐Chinese populations up to now. We set out to determine how SES affects stage at diagnosis at both individual and area levels, from a hospital‐based multicenter 10‐year (2005–2014) retrospective clinical epidemiological study of 7184 primary lung cancer patients in mainland China. Individual‐level SES data were measured based on two indicators from case report forms of the study: an individual's education and occupation. Seven census indicator variables were used as surrogates for the area‐level SES with principal component analysis (PCA). Multivariate analysis was undertaken using binary logistic regressions and multinomial logit model to describe the association and explore the effect across tertiles on stage after adjusting for demographic variables. There was a significant stepwise gradient of effect across different stages in the highest tertile of area‐level SES, comparing with the lowest tertile of area‐level SES (ORs, 0.77, 0.67, and 0.29 for stage II, III, and IV). Patients with higher education were less likely to have stage IV lung cancer, comparing with the illiterate group (ORs, 0.52, 0.63, 0.71, 0.64 for primary school, middle school, high school, college degree or above subgroup, respectively). Findings suggest that the most socioeconomically deprived areas may be associated with a higher risk of advanced‐stage lung cancer, and increasing educational level may be correlated with a lower risk to be diagnosed at advanced stage in both men and women.

Geographical Variation and Factors Associated with Non-Small Cell Lung Cancer in Manitoba

Background

Screening decreases non-small cell lung cancer (NSCLC) deaths and is recommended by the Canadian Task Force on Preventive Health Care. We investigated risk factor prevalence and NSCLC incidence at a small region level to inform resource allocation for lung cancer screening.

Methods

NSCLC diagnoses were obtained from the Canadian Cancer Registry, then geocoded to 283 small geographic areas (SGAs) in Manitoba. Sociodemographic characteristics of SGAs were obtained from the 2006 Canadian Census and Canadian Community Health Survey. Geographical variation was modelled using a Bayesian spatial Poisson model.

Results

NSCLC incidence in SGAs ranged from 1 to 343 cases per 100,000 population per year. The highest incidence rates were in the Southeastern, Southwestern, and Central regions of Manitoba, while most of Northern Manitoba had lower rates. Poisson regression suggested areas with higher proportions of Aboriginal people and higher average income, and immigrants had lower NSCLC incidence whereas areas with higher proportions of smokers had higher incidence.

Conclusion

On an SGA level, smoking rates remain the most significant factor driving NSCLC incidence. Socioeconomic status and proportions of immigrants or Aboriginal peoples independently impact NSCLC rates. We have identified SGAs in Manitoba to target in policy and infrastructure planning for lung cancer screening.

Socio-economic disparities in long-term cancer survival-10 year follow-up with individual patient data

PURPOSE

Reasons for the social gradient in cancer survival are not fully understood yet. Previous studies were often only able to determine the socio-economic status of the patients from the area they live in, not from their individual socio-economic characteristics.

METHODS

In a multi-centre cohort study with 1633 cancer patients and 10-year follow-up, individual socio-economic position was measured using the indicators: education, job grade, job type, and equivalence income. The effect on survival was measured for each indicator individually, adjusting for age, gender, and medical characteristics. The mediating effect of health behaviour (alcohol and tobacco consumption) was analysed in separate models.

RESULTS

Patients without vocational training were at increased risk of dying (rate ratio (RR) 1.5, 95% confidence interval (CI) 1.1-2.2) compared to patients with the highest vocational training; patients with blue collar jobs were at increased risk (RR 1.2; 95% CI 1.0-1.5) compared to patients with white collar jobs; income had a gradual effect (RR for the lowest income compared to highest was 2.7, 95% CI 1.9-3.8). Adding health behaviour to the models did not change the effect estimates considerably. There was no evidence for an effect of school education and job grade on cancer survival.

CONCLUSIONS

Patients with higher income, better vocational training, and white collar jobs survived longer, regardless of disease stage at baseline and of tobacco and alcohol consumption.

Does socioeconomic status impact physical activity and sleep among children with cancer?

BACKGROUND

Compared with healthy children, pediatric oncology patients have impaired sleep and engage in less physical activity (PA). Socioeconomic status (SES) may be one determinant of PA and sleep among pediatric oncology patients.

PROCEDURE

Between November 12, 2009 and March 27, 2013, 50 pediatric oncology patients between the ages of 8 and 18 years were recruited from an urban children's hospital. PA and sleep were assessed by actigraphy and diaries over 7 days. Fatigue was assessed using the Fatigue Scale. SES was defined by primary payer status of insurance (state or private) and by Median Household Income (MHI) obtained from 2010 U.S. Census block data for residences. MHI was compared to Connecticut state median income ($67,000). Multivariate regression models examined the relationship between SES and PA, sleep and fatigue.

RESULTS

PA and sleep efficiency were strongly correlated (r = 0.31, P = 0.03). Children with state insurance had higher average PA (P = 0.004) than children on private insurance. There were no significant differences in PA or sleep efficiency by block MHI. The 7-day fatigue score was lower among the participants aged 8-12 years in the group with MHI less than $67,000 (P = 0.03), although there was no significant difference among participants aged 13-18 years in the group. There was no difference in mean fatigue scores by insurance status.

CONCLUSIONS

Participants on state insurance had higher PA than those with private insurance. Although block MHI did not influence PA or sleep efficiency among children with cancer, participants aged 8-12 years in a lower MHI block had less fatigue. Future research is needed to further understand how SES influences PA.

A detailed spatial analysis on contrasting cancer incidence patterns in thyroid and lung cancer in Toronto women

Background

Thyroid cancer has been rapidly rising in incidence in Canada; however, in contrast, lung cancer appears to be decreasing in incidence in Canadian men and stable in women. Moreover, disease-related mortality risk is generally very low in TC but high in LC. We performed a geographic spatial analysis in metropolitan Toronto, Canada to determine if there is regional variability of respective risks of thyroid cancer (TC) and lung cancer (LC), among women. Women were of particular interest for this study, given their known predilection for thyroid cancer.

Methods

The postal codes of all females with TC or LC, residing in metropolitan Toronto from 2004 to 2008, were geocoded to point locations according to 2006 Canadian Census data. The data were analysed using a log-Gaussian Cox Process, where the intensity of age-adjusted cancer cases was modelled as a log-linear combination of the population at risk, explanatory variables (race, immigration, and median household income), and a residual spatially varying random effect. For each respective malignancy, statistical models were fit to make quantify the relationship between cancer incidence and explanatory variables.

Results

We included 2230 women with TC and 2412 with LC. The distribution of TC and LC cases contrasted inversely among Toronto neighbourhoods with the highest TC incidence in the Northeast and the highest LC incidence in the Southeast. A higher proportion of Asian ethnicity was associated with higher regional risk of TC and lower risk of LC. A higher proportion of recent immigrants was associated with increased LC and lower TC risk, whereas median household income and proportions of African ethnicity were not significantly associated with risk of either cancer, after adjustment for other socio-demographic variables.

Conclusions

We observed contrasting regional distributions of female TC and LC cases in Toronto. The differences were partly attributed to ethnic composition variability and the proportion of recent immigrants, but substantial unexplained residual variation of incidence patterns of these malignancies exists, suggesting that more individual-level research is needed to explain the regional variability of incidence of these malignancies.

Mediation Analysis for Health Disparities Research

Social epidemiologists often seek to determine the mechanisms that underlie health disparities. This work is typically based on mediation procedures that may not be justified with exposures of common interest in social epidemiology. In this analysis, we explored the consequences of using standard approaches, referred to as the difference and generalized product methods, when mediator-outcome confounders are associated with the exposure. We compared these with inverse probability-weighted marginal structural models, the structural transformation method, doubly robust g-estimation of a structural nested model, and doubly robust targeted minimum loss-based estimation. We used data on 900,726 births from 2003 to 2007 in the Penn Moms study, conducted in Pennsylvania, to assess the extent to which breastfeeding prior to hospital discharge explained the racial disparity in infant mortality. Overall, for every 1,000 births, 3.36 more infant deaths occurred among non-Hispanic black women relative to all other women (95% confidence interval: 2.78, 3.93). Using the difference and generalized product methods to assess the disparity that would remain if everyone breastfed prior to discharge suggested a complete elimination of the disparity (risk difference = -0.87 per 1,000 births; 95% confidence interval: -1.39, -0.35). In contrast, doubly robust methods suggested a reduction in the disparity to 2.45 (95% confidence interval: 2.20, 2.71) more infant deaths per 1,000 births among non-Hispanic black women. Standard approaches for mediation analysis in health disparities research can yield misleading results.

Spatial associations between socioeconomic groups and NO2 air pollution exposure within three large Canadian cities

Previous studies of environmental justice in Canadian cities have linked lower socioeconomic status to greater air pollution exposures at coarse geographic scales, (i.e., Census Tracts). However, studies that examine these associations at finer scales are less common, as are comparisons among cities. To assess differences in exposure to air pollution among socioeconomic groups, we assigned estimates of exposure to ambient nitrogen dioxide (NO2), a marker for traffic-related pollution, from city-wide land use regression models to respondents of the 2006 Canadian census long-form questionnaire in Toronto, Montreal, and Vancouver. Data were aggregated at a finer scale than in most previous studies (i.e., by Dissemination Area (DA), which includes approximately 400-700 persons). We developed simultaneous autoregressive (SAR) models, which account for spatial autocorrelation, to identify associations between NO2 exposure and indicators of social and material deprivation. In Canada's three largest cities, DAs with greater proportions of tenants and residents who do not speak either English or French were characterised by greater exposures to ambient NO2. We also observed positive associations between NO2 concentrations and indicators of social deprivation, including the proportion of persons living alone (in Toronto), and the proportion of persons who were unmarried/not in a common-law relationship (in Vancouver). Other common measures of deprivation (e.g., lone-parent families, unemployment) were not associated with NO2 exposures. DAs characterised by selected indicators of deprivation were associated with higher concentrations of ambient NO2 air pollution in the three largest cities in Canada.

Regional Inequalities in Lung Cancer Mortality in Belgium at the Beginning of the 21st Century: The Contribution of Individual and Area-Level Socioeconomic Status and Industrial Exposure

Being a highly industrialized country with one of the highest male lung cancer mortality rates in Europe, Belgium is an interesting study area for lung cancer research. This study investigates geographical patterns in lung cancer mortality in Belgium. More specifically it probes into the contribution of individual as well as area-level characteristics to (sub-district patterns in) lung cancer mortality. Data from the 2001 census linked to register data from 2001-2011 are used, selecting all Belgian inhabitants aged 65+ at time of the census. Individual characteristics include education, housing status and home ownership. Urbanicity, unemployment rate, the percentage employed in mining and the percentage employed in other high-risk industries are included as sub-district characteristics. Regional variation in lung cancer mortality at sub-district level is estimated using directly age-standardized mortality rates. The association between lung cancer mortality and individual and area characteristics, and their impact on the variation of sub-district level is estimated using multilevel Poisson models. Significant sub-district variations in lung cancer mortality are observed. Individual characteristics explain a small share of this variation, while a large share is explained by sub-district characteristics. Individuals with a low socioeconomic status experience a higher lung cancer mortality risk. Among women, an association with lung cancer mortality is found for the sub-district characteristics urbanicity and unemployment rate, while for men lung cancer mortality was associated with the percentage employed in mining. Not just individual characteristics, but also area characteristics are thus important determinants of (regional differences in) lung cancer mortality.

Exposure to traffic-related air pollution and the risk of developing breast cancer among women in eight Canadian provinces: a case-control study

A few recent studies have reported positive associations between long-term exposure to traffic-related air pollution and the incidence of breast cancer. We capitalized on an existing Canadian multi-site population-based case-control study to further investigate this association. We used the National Enhanced Cancer Surveillance System, a population-based case-control study conducted in eight of 10 Canadian provinces from 1994 to 1997. A total of 1569 breast cancer cases and 1872 population controls who reported at least 90% complete self-reported addresses over the 1975-1994 exposure period were examined. Mean exposure levels to nitrogen dioxide (NO2) (an indicator of traffic-related air pollution) were estimated for this period using three different measures: (1) satellite-derived observations; (2) satellite-derived observations scaled with historical fixed-site measurements of NO2; and (3) a national land-use regression (LUR) model. Proximity to major roads was also examined. Using unconditional logistic regression, stratified by menopausal status, we estimated odds ratios (ORs) adjusted for many individual-level and contextual breast cancer risk factors. We observed positive associations between incident breast cancer and all three measures of NO2 exposure from 1975 to 1994. In fully adjusted models for premenopausal breast cancer, a 10ppb increase in NO2 exposure estimated from the satellite-derived observations, the scaled satellite-derived observations, and the national LUR model produced ORs of 1.26 (95% confidence intervals (CIs): 0.92-1.74), 1.32 (95% CI: 1.05-1.67) and 1.28 (95% CI: 0.92-1.79). For postmenopausal breast cancer, we found corresponding ORs of 1.10 (95% CI: 0.88-1.36), 1.10 (95% CI: 0.94-1.28) and 1.07 (95% CI: 0.86-1.32). Substantial heterogeneity in the ORs was observed across the eight Canadian provinces and reduced ORs were observed when models were restricted to women who had received routine mammography examinations. No associations were found for road proximity measures. This study provides some support for the hypothesis that traffic-related air pollution may be associated with the development of breast cancer, especially in premenopausal women. With the few studies available, further research is clearly needed.

Invited commentary: history of place, life course, and health inequalities-historical geographic information systems and epidemiologic research

In recent years, a large number of studies have investigated the sociogeographical arrangements of health-related characteristics across urban areas. Drawing on theories of "environmental justice," researchers have been concerned with whether there is a social gradient in the spatial distribution of environmental "goods" and "bads." The accompanying article by King and Clarke (Am J Epidemiol. 2015;181(1):17-25) makes an important entry into these debates, as it describes the results of the first national-level US study to examine the relationship between urban form (particularly neighborhood walkability) and various area-level sociodemographic measures. Like many studies in this field, King and Clarke's work was constrained by the availability of certain area-level measures, and they had to rely on data from only a single point in time (2000-2001). For this reason, their results can provide few insights into the processes leading to the geographical arrangement of health-related resources across US cities. The emerging field of "historical geographic information systems" offers possibilities to researchers interested in relationships between place and health. Integrating spatial data from various historical sources can enable the reconstruction of past urban environments. These spatial data, accrued over time and appended with detailed cohort information, will offer analytical opportunities for better understanding how place-based factors influence health and well-being over the life course.

Geographic variation in radon and associated lung cancer risk in Canada

OBJECTIVE

Radon is an important risk factor for lung cancer. Here we use maps of the geographic variation in radon to estimate the lung cancer risk associated with living in high radon areas of Canada.

METHODS

Geographic variation in radon was estimated using two mapping methods. The first used a Health Canada survey of 14,000 residential radon measurements aggregated to health regions, and the second, radon risk areas previously estimated from geology, sediment geochemistry and aerial gamma-ray spectrometry. Lung cancer risk associated with living in these radon areas was examined using a population-based case-control study of 2,390 lung cancer cases and 3,507 controls collected from 1994-1997 in eight Canadian provinces. Residential histories over a 20-year period were used in combination with the two mapping methods to estimate ecological radon exposures. Hierarchical logistic regression analyses were used to estimate odds ratios for lung cancer incidence, after adjusting for a comprehensive set of individual and geographic covariates.

RESULTS

Across health regions in Canada, significant variation in average residential radon concentrations (range: 16-386 Bq/m3) and in high geological-based radon areas (range: 0-100%) is present. In multivariate models, a 50 Bq/m3 increase in average health region radon was associated with a 7% (95% CI: -6-21%) increase in the odds of lung cancer. For every 10 years that individuals lived in high radon geological areas, the odds of lung cancer increased by 11% (95% CI: 1-23%).

CONCLUSIONS

These findings provide further evidence that radon is an important risk factor for lung cancer and that risks are unevenly distributed across Canada.