The enduring and evolving relationship between social class and breast cancer burden: a review of the literature

Medicaid expansion in California and breast cancer incidence across neighborhoods with varying social vulnerabilities

PURPOSE

To investigate changes in breast cancer incidence rates associated with Medicaid expansion in California.

METHODS

We extracted yearly census tract-level population counts and cases of breast cancer diagnosed among women aged between 20 and 64 years in California during years 2010-2017. Census tracts were classified into low, medium and high groups according to their social vulnerability index (SVI). Using a difference-in-difference (DID) approach with Poisson regression models, we estimated the incidence rate, incidence rate ratio (IRR) during the pre- (2010-2013) and post-expansion periods (2014-2017), and the relative IRR (DID estimates) across three groups of neighborhoods.

RESULTS

Prior to the Medicaid expansion, the overall incidence rate was 93.61, 122.03, and 151.12 cases per 100,000 persons among tracts with high, medium, and low-SVI, respectively; and was 96.49, 122.07, and 151.66 cases per 100,000 persons during the post-expansion period, respectively. The IRR between high and low vulnerability neighborhoods was 0.62 and 0.64 in the pre- and post-expansion period, respectively, and the relative IRR was 1.03 (95% CI 1.00 to 1.06, p = 0.026). In addition, significant DID estimate was only found for localized breast cancer (relative IRR = 1.05; 95% CI, 1.01 to 1.09, p = 0.049) between high and low-SVI neighborhoods, not for regional and distant cancer stage.

CONCLUSIONS

The Medicaid expansion had differential impact on breast cancer incidence across neighborhoods in California, with the most pronounced increase found for localized cancer stage in high-SVI neighborhoods. Significant pre-post change was only found for localized breast cancer between high and low-SVI neighborhoods.

Social Representativeness and Intervention Adherence-A Systematic Review of Clinical Physical Activity Trials in Breast Cancer Patients

Objectives

Representativeness in physical activity randomised controlled trials (RCT) in breast cancer patients is essential to analyses of feasibility and validity considering privileged- social groups. A step-by-step exclusion of less privileged groups through the trial process could reinforce health inequality. This study aimed at examining representativeness in breast cancer (BC) physical activity trials, investigate associations between socio-economic status (SES) and intervention adherence, and explore associations between representativeness and the relationship between SES and intervention adherence.

Methods

Systematic, computerised searches were performed in PubMed, CINAHL, AMED, EMBASE and PsycINFO. Additional citation-based searches retrieved 37 articles. Distributions of education level, ethnicity, and marital status in study samples were compared to national populations data to estimate representativeness in less privileged groups.

Results

A preponderance of studies favoured educated, married and white patients. Only six studies reported SES-adherence associations, hampering conclusions on this relationship and possible associations between representativeness and an SES-adherence relationship.

Conclusion

Less educated, unmarried and non-white individuals may be underrepresented in BC physical activity RCTs, while SES-adherence associations in such trials are inconclusive. Unintentional social misrepresentations may indicate that disguised inequity warrants revived attention.

The Risk of Cancer-Associated and Radiotherapy-Associated Cardiovascular Diseases among Patients with Breast Cancer

BACKGROUND

The cardio-related issues should be emphasized as the survival rates of breast cancer increased. We investigated the risk of coronary artery disease (CAD) and stroke due to breast cancer or radiotherapy.

METHODS

In this retrospective cohort study, breast cancer patients diagnosed between 2007 and 2016 were recruited from Taiwan Cancer Registry Database and were followed until the end of 2018 by linking with the Taiwan National Health Insurance Database. The general population was randomly selected from the whole population in 2007. Standardized incidence ratios (SIR) were calculated to compare the risk of CAD and stroke between patients and the general population. Within the cohort, we included the patients diagnosed between 2011 and 2016. Cox proportional hazards model and subdistribution hazard function were used to investigate the associations of radiotherapy with the risk of CAD and stroke.

RESULTS

Overall SIR of CAD was 0.82 (95% confidence interval [CI]: 0.78-0.86), while were 1.43 and 1.08 (95% CI: 1.30-1.55 and 1.00-1.16) 1 and 2 years after diagnosis, respectively. Overall SIR of stroke was 0.63 (95% CI: 0.60-0.67), the results were similar after considering the time since diagnosis. The adjusted hazard ratios (HR) for the associations of radiotherapy with CAD and stroke risk were 0.91 (95% [CI] = 0.76-1.09) and 0.84 (95% CI = 0.68-1.04), respectively. The results were similar by using subdistribution hazard function.

CONCLUSIONS

The risk of CAD was higher within the first 2 years of breast cancer diagnosis. We found no association between radiotherapy and the risk of CAD and stroke.

Association between breast diseases and symptomatic uterine fibroids by using South Korean National Health Insurance database

Both the uterus and breasts have sex hormone dependence, yet there are few studies on the association between breast disease and uterine fibroids (UFs). The purpose of this study was to investigate the incidence of benign breast disease (BBD), carcinoma in situ (CIS), and breast cancer (BC) in women treated for UFs compared to women who were not treated for UFs. This retrospective cohort study used national health insurance data from January 1st, 2011, to December 31st, 2020. We selected women between 20 and 50 years old who (1) were treated for UFs (UF group) or (2) visited medical institutions for personal health screening tests without UFs (control group). We analyzed independent variables such as age, socioeconomic status (SES), region, Charlson comorbidity index (CCI), delivery status, menopausal status, menopausal hormone therapy (MHT), endometriosis, hypertension (HTN), diabetes mellitus (DM), and dyslipidemia based on the first date of uterine myomectomy in the UF group and the first visiting date for health screening in the non-UF group. There were 190,583 and 439,940 participants in the UF and control groups, respectively. Compared with those of the control group, the RRs of BBD, CIS, and BC were increased in the UF group. The hazard ratios (HRs) of BBD, CIS, and BC in the UF group were 1.335 (95% confidence interval (CI) 1.299-1.372), 1.796 (95% CI 1.542-2.092), and 1.3 (95% CI 1.198-1.41), respectively. When we analyzed the risk of BC according to age at inclusion, UFs group had the increased risk of BCs in all age groups in comparison with control group. Women with low SES (HR 0.514, 95% CI 0.36-0.734) and living in rural areas (HR 0.889, 95% CI 0.822-0.962) had a lower risk of BC. Our study showed that women with UFs had a higher risk of BBD, CIS, and BC than those without UFs. This result suggests that women with UFs should be more conscious of BC than those without UFs. Therefore, doctors should consider recommending regular breast self-exams, mammography, or ultrasound for the early detection of BC in women with UFs.

Early life adversity, reproductive history and breast cancer risk

Background and objectives

Individuals who experience early life adversity are at an increased risk for chronic disease later in life. Less is known about how early life factors are associated with cancer susceptibility. Here, we use a life history framework to test whether early life adversity increases the risk of breast cancer. We predict that early life adversity can shift investment in somatic maintenance and accelerate the timing of reproduction, which may mediate or interact with the risk of breast cancer.

Methodology

We use population-wide data from the Utah Population Database (UPDB) and Utah Cancer Registry, leading to 24 957 cases of women diagnosed with breast cancer spanning 20 years (1990-2010) and 124 785 age-matched controls. We generated a cumulative early life adversity summation score to evaluate the interaction (moderation) and mediation between early life adversity, reproductive history and their association with breast cancer risk.

Results

Our analyses led to three key findings: (i) more early life adversity, when considered as a main effect, accelerates the time to first birth and death, (ii) early age at first birth and high parity decreases the risk of breast cancer and (iii) we find no association between early adversity and breast cancer risk either as a main effect or in its interaction with reproductive history.

Conclusion and implications

Early adversity elevates the risk of overall mortality through mechanisms other than breast cancer risk. This suggests early life factors can generate different effects on health. Future work should incorporate more complex view of life history patterns, including multiple life stages, when making predictions about cancer susceptibility.

Major depression disorder may causally associate with the increased breast cancer risk: Evidence from two-sample mendelian randomization analyses

INTRODUCTION

Major depression disorder (MDD) has been associated with increased breast cancer risk in epidemiological studies; however, it is still unknown whether this association is causal or not. The aim of this study is to determine the causal relationship between MDD and breast cancer risk.

METHODS

Two-sample Mendelian randomization (MR) analyses with 92 single-nucleotide polymorphisms (SNPs) significantly associated with MDD as instrumental variables (IVs) were performed. Effects of these SNPs on breast cancer in women were estimated in the Breast Cancer Association Consortium (122,977 cases and 105,974 controls) using inverse variance weighted (IVW), weighted median and multivariable MR models. Heterogeneity and pleiotropy effects were assessed based on IVW and MR-Egger regression model, respectively.

RESULTS

An 8.7% increased risk of overall breast cancer [odds ratio (OR) = 1.087; 95% confidence interval (CI) 1.011-1.170; P = 0.025] per log-odds ratio increment of MDD risk based on the IVW model was noticed. Similar results were obtained with the multivariable MR model (OR = 1.118, 95% CI = 1.010-1.237; P = 0.031). An increment but not statistically significant causality association was noticed between MDD and risk of ER+ (OR = 1.098, 95% CI = 0.984-1.227; P = 0.093) or ER- (OR = 1.129, 95% CI = 0.982-1.297; P = 0.089) breast cancer under multivariable MR model. No significant pleiotropy effects were observed for the IVs in the two-sample MR studies.

CONCLUSIONS

The results suggested that a genetic predisposition of MDD is causally associated with overall breast cancer risk; however, the underlying biological mechanisms are worthy of further study.

Socioeconomic status and its relation with breast cancer recurrence and survival in young women in the Netherlands

BACKGROUND

Associations between socioeconomic status (SES) and breast cancer survival are most pronounced in young patients. We further investigated the relation between SES, subsequent recurrent events and mortality in breast cancer patients < 40 years. Using detailed data on all recurrences that occur between date of diagnosis of the primary tumor and last observation, we provide a unique insight in the prognosis of young breast cancer patients according to SES.

METHODS

All women < 40 years diagnosed with primary operated stage I-III breast cancer in 2005 were selected from the nationwide population-based Netherlands Cancer Registry. Data on all recurrences within 10 years from primary tumor diagnosis were collected directly from patient files. Recurrence patterns and absolute risks of recurrence, contralateral breast cancer (CBC) and mortality - accounting for competing risks - were analysed according to SES. Relationships between SES, recurrence patterns and excess mortality were estimated using a multivariable joint model, wherein the association between recurrent events and excess mortality (expected mortality derived from the general population) was included.

RESULTS

We included 525 patients. The 10-year recurrence risk was lowest in high SES (18.1%), highest in low SES (29.8%). Death and CBC as first events were rare. In high, medium and low SES 13.2%, 15.3% and 19.1% died following a recurrence. Low SES patients had shorter median time intervals between diagnosis, first recurrence and 10-year mortality (2.6 and 2.7 years, respectively) compared to high SES (3.5 and 3.3 years, respectively). In multivariable joint modeling, high SES was significantly related to lower recurrence rates over 10-year follow-up, compared to low SES. A strong association between the recurrent event process and excess mortality was found.

CONCLUSIONS

High SES is associated with lower recurrence risks, less subsequent events and better prognosis after recurrence over 10 years than low SES. Breast cancer risk factors, adjuvant treatment adherence and treatment of recurrence may possibly play a role in this association.

Impact of Birth Cohorts in Breast Cancer Risk Among South Korean Women

BACKGROUND

The incidence of breast cancer among South Korean women, a historically low-risk population, has increased over the past 3 decades, with marked changes in socioeconomic environment by birth cohort.

OBJECTIVES

We investigated associations between breast cancer risk and reproductive factors as well as the impact of birth cohort in those associations.

METHOD

This was a cross-sectional study of data from the Korea National Health and Nutrition Examination Survey for 2013-2016. Data from 10 012 parous women 30 years or older were analyzed using descriptive statistics and Cox multivariate regression after adjusting for socioeconomic status, educational level, occupation, and birth cohort.

RESULTS

Of the reproductive factors considered-age at menarche, number of pregnancies, age at first birth, age at last birth, breastfeeding duration, and use of oral contraceptives-only age at menarche was associated with breast cancer risk. Higher educational level, not having an occupation, and younger birth cohort were also associated with increased risk of breast cancer, with birth cohort the strongest of these impact factors.

CONCLUSION

Whereas the relationship between reproductive factors and breast cancer risk was relatively weak, birth cohort was the most important risk factor for breast cancer.

IMPLICATIONS FOR PRACTICE

The results provide a basis and a rationale for developing birth cohort-based clinical guidelines for breast cancer prevention and early detection, treatment, and survivorship. These findings should also be useful to researchers in other countries experiencing rapid changes in breast cancer incidence.

Socioeconomic disparities in cancer incidence and mortality in England and the impact of age-at-diagnosis on cancer mortality

Background

We identify socioeconomic disparities by region in cancer morbidity and mortality in England for all-cancer and type-specific cancers, and use incidence data to quantify the impact of cancer diagnosis delays on cancer deaths between 2001–2016.

Methods and findings

We obtain population cancer morbidity and mortality rates at various age, year, gender, deprivation, and region levels based on a Bayesian approach. A significant increase in type-specific cancer deaths, which can also vary among regions, is shown as a result of delay in cancer diagnoses. Our analysis suggests increase of 7.75% (7.42% to 8.25%) in female lung cancer mortality in London, as an impact of 12-month delay in cancer diagnosis, and a 3.39% (3.29% to 3.48%) increase in male lung cancer mortality across all regions. The same delay can cause a 23.56% (23.09% to 24.30%) increase in male bowel cancer mortality. Furthermore, for all-cancer mortality, the highest increase in deprivation gap happened in the East Midlands, from 199 (186 to 212) in 2001, to 239 (224 to 252) in 2016 for males, and from 114 (107 to 121) to 163 (155 to 171) for females. Also, for female lung cancer, the deprivation gap has widened with the highest change in the North West, e.g. for incidence from 180 (172 to 188) to 272 (261 to 282), whereas it has narrowed for prostate cancer incidence with the biggest reduction in the South West from 165 (139 to 190) in 2001 to 95 (72 to 117) in 2016.

Conclusions

The analysis reveals considerable disparities in all-cancer and some type-specific cancers with respect to socioeconomic status. Furthermore, a significant increase in cancer deaths is shown as a result of delays in cancer diagnoses which can be linked to concerns about the effect of delay in cancer screening and diagnosis during the COVID-19 pandemic. Public health interventions at regional and deprivation level can contribute to prevention of cancer deaths.

The role of residential history in cancer research: A scoping review

The role of residential history in cancer prevention, diagnosis, treatment, and survivorship is garnering increasing attention in cancer research. To our knowledge, there is no comprehensive synthesis of the current state of knowledge in the field. We reviewed the extant literature on this topic and conducted a scoping analysis to examine two main research questions: (a) To what degree, and how, have researchers accounted for residential history/mobility in cancer research? and (b) What are the gaps in the literature based on a knowledge synthesis using scoping review and concept mapping? To answer these questions, this scoping analysis focuses on how researchers compile, analyze and discuss residential history/mobility in studies on cancer. The study is focused on peer-reviewed articles from 6 different datasets (PubMed, Cinahl, Scopus, Web of Science and JSTOR, ERIC) from 1990 to August 2020. The review captured 1951 results in total, which was scoped to 281 relevant peer-reviewed journal articles. First, we examined these articles based on cancer continuum, cancer type and the main theme. Second, we identified 21 main themes and an additional 16 sub-themes in the pool of the selected articles. We utilized concept mapping to provide a conceptual framework and to highlight the underlying socioecological assumptions and paradigms. Results show that cancer research incorporating residential histories is primarily focused on incidence and estimating cumulative exposure, with little consideration across the cancer continuum. Additionally, our review suggests that although the social environment plays an important role across the cancer continuum, a small number of articles were focused on such factors and this area remains relatively unexplored. Additionally, the expansion of interdisciplinary research on residential mobility before and after cancer diagnosis will enhance understanding of the role of environmental and socioeconomic characteristics and exposures on cancer continuum.

Identifying county-level factors for female breast cancer incidence rate through a large-scale population study

Female breast cancer (FBC) incidence rate (IR) varies greatly across counties in the United States (U.S.). Factors contributing to these geographic disparities have not been fully understood at the population level. In this study, we investigated the relationships between the county-level FBC IR and a diverse set of variables in demographics, socioeconomics, life style, health care accessibility, and environment. Our study included 1,277 counties in the U.S. where the female population was 10,000 or above for at least one race/ethnicity. After controlling for the racial/ethnic and other significant factors, percent of husband-wife family households (pHWFH) for a racial/ethnic group in a county is negatively associated with FBC IR (p < 0.001). A 10% increase in married family households may lower a county's IR by 5.2 cases per 100,000 females per year. We also found that PM2.5 (fine inhalable particles with a diameter of 2.5 micrometers or less) is positively associated with FBC IR (p < 0.001). Counties with the highest level of PM2.5 have approximately 4 additional FBC new cases per 100,000 females per year than counties with the lowest level of PM2.5. Furthermore, we found that the county-level factors contributing to FBC IR vary significantly for different racial groups using race-specific models. While confirming most of the previously known patient- and neighborhood-level risk factors (such as race/ethnicity, income, and health care accessibility), our study identified two significant county-level factors contributing to the spatial disparity of FBC IR across the U.S. The newly-identified beneficial factor (marriage) and risk factor (PM2.5), together with the verified known factors, may help provide insights to officials of health departments/organizations for them to make decisions on cancer intervention strategies.

Social inequalities in breast cancer screening: evaluating written communications with immigrant Haitian women in Montreal

Background

The province of Quebec (Canada) has implemented a breast cancer screening program to diagnose this cancer at an early stage. The strategy is to refer women 50 to 69 years old for a mammogram every two years by sending an invitation letter that acts as a prescription. Ninety per cent (90%) of deaths due to breast cancer occur in women aged 50 and over. Numerous studies have shown social inequalities in health for most diseases. With breast cancer, a significant paradox arises: its incidence is lower among disadvantaged women and yet, more of them die from this disease. The health care system might play a role in this inequality. The scientific literature documents the potential for creating such inequalities when prevention does not consider equity among social groups. Immigrant women are often disadvantaged. They die of breast cancer more than non-immigrants. Studies attribute this to late-stage diagnosis due to poor adherence to mammography screening programs.

Purpose of the study

The main objective of our research is to assess how Haitian immigrant women in Montreal are reached by the Quebec Breast Cancer Screening Program, and specifically how they perceive the mammogram referral letter sent by the program.

Methods

The study uses a two-step qualitative method: i) In-depth interviews with influential community workers to identify the most relevant issues; ii) Focus groups with disadvantaged women from Montreal’s Haitian community.

Results

A mammogram referral letter from the Breast Cancer Screening Program may be a barrier to compliance with mammography by underprivileged Haitian women in Montreal. This might be attributable to a low level of literacy, poor knowledge of the disease, and lack of financial resources.

Conclusion

Barriers may be underestimated in underprivileged immigrant and non-immigrant communities. A preventive strategy must be adapted to different sub-groups and must also take into account lower literacy levels. To increase mammography uptake, it is crucial that the benefits of prevention be clearly identified and described in understandable terms. Finally, economic access to follow-up measures should be considered.

Socioeconomic inequalities in stage-specific breast cancer incidence: a nationwide registry study of 1.1 million young women in Norway, 2000-2015

BACKGROUND

Women with high socioeconomic status (SES) have the highest incidence rates of breast cancer. We wanted to determine if high SES women only have higher rates of localized disease, or whether they also have higher rates of non-localized disease. To study this, we used data on a young population with universal health care, but not offered screening.

MATERIAL AND METHODS

Using individually linked registry data, we compared stage-specific breast cancer incidence, by education level and income quintile, in a Norwegian cohort of 1,106,863 women aged 30-48 years during 2000-2015 (N = 7531 breast cancer cases). We calculated stage-specific age-standardized rates and incidence rate ratios and rate differences using Poisson models adjusted for age, period and immigration history.

RESULTS

Incidence of localized and regional disease increased significantly with increasing education and income level. Incidence of distant stage disease did not vary significantly by education level but was significantly reduced in the four highest compared to the lowest income quintile. The age-standardized rates for tertiary versus compulsory educated women were: localized 28.2 vs 19.8, regional 50.8 vs 40.4 and distant 2.3 vs 2.6 per 100,000 person-years. The adjusted incidence rate ratios (tertiary versus compulsory) were: localized 1.40 (95% CI 1.25-1.56), regional 1.25 (1.15-1.35), distant 0.90 (0.64-1.26). The age-standardized rates for women in the highest versus lowest income quintile were: localized 28.9 vs 17.7, regional 52.8 vs 41.5 and distant 2.3 vs 3.2 per 100,000 person-years. The adjusted incidence rate ratios (highest versus lowest quintile) were: localized 1.63 (1.42-1.87), regional 1.27 (1.09-1.32), distant 0.64 (0.43-0.94).

CONCLUSION

Increased breast cancer rates among young high SES women is not just increased detection of small localized tumors, but also increased incidence of tumors with regional spread. The higher incidence of young high SES women is therefore real and not only because of excessive screening.

Risk factors for inflammatory and non-inflammatory breast cancer in North Africa

PURPOSE

Studies of the etiology of inflammatory breast cancer (IBC), a rare but aggressive breast cancer, have been hampered by limited risk factor information. We extend previous studies by evaluating a broader range of risk factors.

METHODS

Between 2009 and 2015, we conducted a case-control study of IBC at six centers in Egypt, Tunisia, and Morocco; enrolled were 267 IBC cases and for comparison 274 non-IBC cases and 275 controls, both matched on age and geographic area to the IBC cases. We administered questionnaires and collected anthropometric measurements for all study subjects. We used multiple imputation methods to account for missing values and calculated odds ratios (ORs) and 95% confidence intervals (CIs) using polytomous logistic regression comparing each of the two case groups to the controls, with statistical tests for the difference between the coefficients for the two case groups.

RESULTS

After multivariable adjustment, a livebirth within the previous 2 years (OR 4.6; 95% CI 1.8 to 11.7) and diabetes (OR 1.8; 95% CI 1.1 to 3.0) were associated with increased risk of IBC, but not non-IBC (OR 0.9; 95% CI 0.3 to 2.5 and OR 0.9; 95% CI 0.5 to 1.6 for livebirth and diabetes, respectively). A family history of breast cancer, inflammatory-like breast problems, breast trauma, and low socioeconomic status were associated with increased risk of both tumor types.

CONCLUSIONS

We identified novel risk factors for IBC and non-IBC, some of which preferentially increased risk of IBC compared to non-IBC. Upon confirmation, these findings could help illuminate the etiology and aid in prevention of this aggressive cancer.

Cancer morbidity trends and regional differences in England-A Bayesian analysis

Reliable modelling of the dynamics of cancer morbidity risk is important, not least due to its significant impact on healthcare and related policies. We identify morbidity trends and regional differences in England for all-cancer and type-specific incidence between 1981 and 2016. We use Bayesian modelling to estimate cancer morbidity incidence at various age, year, gender, and region levels. Our analysis shows increasing trends in most rates and marked regional variations that also appear to intensify through time in most cases. All-cancer rates have increased significantly, with the highest increase in East, North West and North East. The absolute difference between the rates in the highest- and lowest-incidence region, per 100,000 people, has widened from 39 (95% CI 33-45) to 86 (78-94) for females, and from 94 (85-104) to 116 (105-127) for males. Lung cancer incidence for females has shown the highest increase in Yorkshire and the Humber, while for males it has declined in all regions with the highest decrease in London. The gap between the highest- and lowest-incidence region for females has widened from 47 (42-51) to 94 (88-100). Temporal change in in bowel cancer risk is less manifested, with regional heterogeneity also declining. Prostate cancer incidence has increased with the highest increase in London, and the regional gap has expanded from 33 (30-36) to 76 (69-83). For breast cancer incidence the highest increase has occurred in North East, while the regional variation shows a less discernible increase. The analysis reveals that there are important regional differences in the incidence of all-type and type-specific cancers, and that most of these regional differences become more pronounced over time. A significant increase in regional variation has been demonstrated for most types of cancer examined here, except for bowel cancer where differences have narrowed.

A Cross-Sectional Study Evaluating Potential Differences in the Need for Cancer Survivorship Care in Relation to Patients' Socioeconomic Status

Background

There seems to be inequity within cancer survivorship care in primary care settings related to gender, shorter education, and early poor health, but there is uncertainty regarding the character of the needs in hospital and in primary care settings and whether there is inequity regarding meeting these needs. This study aims to describe potential differences in needs among patients in hospital and in primary care settings, and to assess the need for survivorship care and rehabilitation in patients with cancer in relation to socioeconomic status.

Methods

In a cross-sectional study including patients in hospital (n = 89) and primary care settings (n = 99), information from needs assessments was linked with population-based data on socioeconomic status via unique personal identification numbers. The association between socioeconomic status and stated needs was analyzed separately for patients in hospital and primary care settings, with adjustment for age and gender.

Results

A total of 90% patients expressed one or more needs in the physical area, 51% in the emotional area, and 40% in the practical area. Patients in primary care expressed more needs than patients in hospital. Men expressed more needs than women in primary care (adjusted odds ratio (OR) (95% confidence interval (CI)): 2.66 (1.04 - 6.79)). The results indicate that higher socioeconomic status is associated with fewer stated needs.

Conclusions

This study suggests that the association between gender and stated needs may depend on healthcare setting and confirms that higher socioeconomic status in relation to civil status, educational level, income, and labor market status is associated with fewer stated needs.

Relation between socioeconomic variables and surgical, systemic and radiation treatment in a cohort of patients with breast cancer in an urban Canadian centre

Background

Studies have shown an association between socioeconomic status and breast cancer treatment. We examined the relation between socioeconomic status and the treatment of breast cancer (surgical, systemic and radiation) in a universal health care system.

Methods

Data from a single urban Canadian centre were collected for consecutive patients who received a diagnosis of breast cancer from January 2010 to December 2011. Variables included patient and disease factors, surgery type, systemic and radiation treatment, and breast reconstruction. Socioeconomic variables were obtained from 2006 Canadian census data. We used multivariable logistic regression to identify predictors of breast cancer treatment.

Results

A total of 721 patients were treated for breast cancer during the study period. Socioeconomic variables were not related to type of breast surgery for breast cancer. Age less than 50 years, having a first-degree relative with breast cancer and income status were predictors of breast reconstruction. Employment status was a consistent predictor of systemic and radiation treatment.

Conclusion

Employment consistently predicted systemic and radiation treatment, and age and income were predictors of breast reconstruction in a universal health care system. Further research is required to determine precisely how socioeconomic factors affect care and to minimize possible disparities in delivery of health care services.

Cancer Incidence and Multilevel Measures of Residential Economic and Racial Segregation for Cancer Registries

BACKGROUND

The handful of studies (<30) on cancer and residential segregation have focused on racial segregation, primarily at the city/town level. We tested a priori hypotheses about choice of measure and level by extending use of the Index of Concentration at the Extremes (ICE) to quantify both economic and racial residential segregation, singly and combined, and conducted analyses for the total population and stratified by race/ethnicity.

METHODS

Outcomes comprised Massachusetts incidence rates (2010-2014) for invasive breast, cervical, and lung cancer, analyzed in relation to census tract and city/town ICE measures for income, race/ethnicity, race/ethnicity + income, and the federal poverty line. Multilevel Poisson regression modeled observed counts of incident cases.

RESULTS

Both choice of metric and level mattered. As illustrated by cervical cancer, in models including both the census tract and city/town levels, the rate ratio for the worst to best quintile for the total population was greatest at the census tract level for the ICE for racialized economic segregation (3.0, 95% confidence interval [CI] = 2.1 to 4.3) and least for the poverty measure (1.9, 95% CI = 1.4 to 2.6), with null associations at the city/town level. In analogous models with both levels for lung cancer, however, for the non-Hispanic black and Hispanic populations, the rate ratios for, respectively, the ICE and poverty measures, were larger (and excluded 1) at the city/town compared with the census tract level.

CONCLUSIONS

Our study suggests that the ICE for racialized economic segregation, at multiple levels, can be used to improve monitoring and analysis of cancer inequities.

Understanding the effects of socioeconomic status along the breast cancer continuum in Australian women: a systematic review of evidence

Background

Globally, the provision of equitable outcomes for women with breast cancer is a priority for governments. However, there is growing evidence that a socioeconomic status (SES) gradient exists in outcomes across the breast cancer continuum – namely incidence, diagnosis, treatment, survival and mortality. This systematic review describes this evidence and, because of the importance of place in defining SES, findings are limited to the Australian experience.

Methods

An on-line search of PubMed and the Web of Science identified 44 studies published since 1995 which examined the influence of SES along the continuum. The critique of studies included the study design, the types and scales of SES variable measured, and the results in terms of direction and significance of the relationships found. To aid in the interpretation of results, the findings were discussed in the context of a systems dynamic feedback diagram.

Results

We found 67 findings which reported 107 relationships between SES within outcomes along the continuum. Results suggest no differences in the participation in screening by SES. Higher incidence was reported in women with higher SES whereas a negative association was reported between SES and diagnosis. Associations with treatment choice were specific to the treatment choice undertaken. Some evidence was found towards greater survival for women with higher SES, however, the evidence for a SES relationship with mortality was less conclusive.

Conclusions

In a universal health system such as that in Australia, evidence of an SES gradient exists, however, the strength and direction of this relationship varies along the continuum. This is a complex relationship and the heterogeneity in study design, the SES indicator selected and its representative scale further complicates our understanding of its influence. More complex multilevel studies are needed to better understand these relationships, the interactions between predictors and to reduce biases introduced by methodological issues.

Disparities in cancer incidence by area-level socioeconomic status in the French West Indies

PURPOSE

Social inequalities in cancer incidence and mortality have been reported in France, but no data are available for the French overseas territories. Our objective was to explore the association between cancer incidence and the socioeconomic level of the residence area in the French West Indies.

METHODS

Cancer incidence data were obtained from the cancer registries of Guadeloupe and Martinique (2009-2010). To assess socioeconomic status, we developed a specific index of social deprivation from census data at a small area level. We used Bayesian methods to evaluate the association between cancer incidence and the deprivation index, for all cancers combined and for the major cancer sites.

RESULTS

There was no clear association between area-based deprivation and the incidence of all cancers combined. In men, higher area deprivation was associated with a higher incidence of prostate cancer (relative risk (RR) 1.25, 95% credible interval (CI) 1.04-1.49; RR 1.08, CI 0.91-1.29 in the categories of intermediate and high deprivation, respectively, compared to low deprivation), but was not associated with respiratory cancer. Women living in the most deprived areas had a higher incidence of stomach (RR 1.77, CI 1.12-2.89), breast (RR 1.15, CI 0.90-1.45), and cervical (RR 1.13, CI 0.63-2.01) cancers and a lower incidence of respiratory cancer (RR 0.65, CI 0.38-1.11).

CONCLUSION

These first results in the French West Indies suggest specific patterns for some cancer sites that need to be further investigated.

Geography of breast cancer incidence according to age & birth cohorts

PURPOSE

Geographic variation in breast cancer incidence across Connecticut was examined according to age and birth cohort -specific groups.

METHODS

We assigned each of 60,937 incident breast cancer cases diagnosed in Connecticut, 1986-2009, to one of 828 census tracts around the state. Global and local spatial statistics estimated rate variation across the state according to age and birth cohorts.

RESULTS

We found the global distribution of incidence rates across places to be more heterogeneous for younger women and later birth cohorts. Concurrently, the spatial scan identified more locations with significantly high rates that pertained to larger proportions of at-risk women within these groups. Geographic variation by age groups was more pronounced than by birth cohorts.

CONCLUSION

Geographic patterns of cancer incidence exhibit differences within and across age and birth cohorts. With the continued insights from descriptive epidemiology, our capacity to effectively limit spatial disparities in cancer will improve.

Intersection of Race/Ethnicity and Socioeconomic Status in Mortality After Breast Cancer

We investigated social disparities in breast cancer (BC) mortality, leveraging data from the California Breast Cancer Survivorship Consortium. The associations of race/ethnicity, education, and neighborhood SES (nSES) with all-cause and BC-specific mortality were assessed among 9372 women with BC (diagnosed 1993-2007 in California with follow-up through 2010) from four racial/ethnic groups [African American, Asian American, Latina, and non-Latina (NL) White] using Cox proportional hazards models. Compared to NL White women with high-education/high-nSES, higher all-cause mortality was observed among NL White women with high-education/low-nSES [hazard ratio (HR) (95 % confidence interval) 1.24 (1.08-1.43)], and African American women with low-nSES, regardless of education [high education HR 1.24 (1.03-1.49); low-education HR 1.19 (0.99-1.44)]. Latina women with low-education/high-nSES had lower all-cause mortality [HR 0.70 (0.54-0.90)] and non-significant lower mortality was observed for Asian American women, regardless of their education and nSES. Similar patterns were seen for BC-specific mortality. Individual- and neighborhood-level measures of SES interact with race/ethnicity to impact mortality after BC diagnosis. Considering the joint impacts of these social factors may offer insights to understanding inequalities by multiple social determinants of health.

The relative effect of mammographic screening on breast cancer mortality by socioeconomic status

Breast cancer incidence and mortality are higher in women with a high socioeconomic status (SES). The potential to prevent death from breast cancer is therefore greater in the high SES group. This does, however, require that the effectiveness of screening in the high SES group is equal to or greater than the effectiveness in the low SES group. The aim of this study is to assess the relative effectiveness of mammographic screening on breast cancer mortality by SES.In Nijmegen, the Netherlands, women are invited to participate in biennial mammographic screening since 1975. Postal code is collected at each round and is used to calculate the SES of each woman based on the SES indicator of the Netherlands Institute for Social Research. The Dutch average was used to classify the SES score of each woman as either high or low. We designed a case-control study to investigate the effect of mammographic screening in women aged 50 to 75, 40 to 75, and 50 to 69 years, and calculated the odds ratios (ORs) and 95% confidence intervals (CIs).Among the women invited to the mammographic screening program in Nijmegen, 10% had a high SES. In women aged 50 to 75 years, the breast cancer death rate was 38% lower in screened women than in unscreened women. The ORs for women with high SES (OR 0.82, 95% CI 0.31-2.19) and low SES did not differ significantly (OR 0.61, 95% CI 0.47-0.78).Mammographic screening reduces breast cancer mortality, but we did not observe a significant difference in the relative effectiveness of screening by SES. If the effectiveness of mammographic screening is indeed not dependent on SES status, the absolute number of breast cancer deaths prevented by mammographic screening will be greater in the high SES than low SES group, because women with a high SES have a greater risk of breast cancer death.

A life course approach to explore the biological embedding of socioeconomic position and social mobility through circulating inflammatory markers

Lower socioeconomic position (SEP) has consistently been associated with poorer health. To explore potential biological embedding and the consequences of SEP experiences from early life to adulthood, we investigate how SEP indicators at different points across the life course may be related to a combination of 28 inflammation markers. Using blood-derived inflammation profiles measured by a multiplex array in 268 participants from the Italian component of the European Prospective Investigation into Cancer and Nutrition cohort, we evaluate the association between early life, young adulthood and later adulthood SEP with each inflammatory markers separately, or by combining them into an inflammatory score. We identified an increased inflammatory burden in participants whose father had a manual occupation, through increased plasma levels of CSF3 (G-CSF; β = 0.29; P = 0.002), and an increased inflammatory score (β = 1.96; P = 0.029). Social mobility was subsequently modelled by the interaction between father's occupation and the highest household occupation, revealing a significant difference between "stable Non-manual" profiles over the life course versus "Manual to Non-manual" profiles (β = 2.38, P = 0.023). Low SEP in childhood is associated with modest increase in adult inflammatory burden; however, the analysis of social mobility suggests a stronger effect of an upward social mobility over the life course.

Risks of developing breast and colorectal cancer in association with incomes and geographic locations in Texas: a retrospective cohort study

BACKGROUND

No study has been conducted to investigate the spatial pattern and association of socioeconomic status (such as income) with breast and colorectal cancer incidence in Texas, United States. This study aimed to determine whether median household income was associated with the risk of developing breast and colorectal cancer in Texas and to identify higher cancer risks by race/ethnicity and geographic areas.

METHODS

This was a retrospective cohort study with an ecological component in using aggregated measures at the county level. We identified 243,677 women with breast cancer and 155,534 men and women with colorectal cancer residing in 254 counties in Texas in 1995-2011 from the public-use dataset of Texas Cancer Registry. The denominator population and median household income at the county level was obtained from the U.S. Bureau of the Census. Cancer incidence rates were calculated as number of cases per 100,000 persons and age-adjusted using the 2000 US population data. We used the ArcGIS v10.1 (geographic information system software) to identify multiple clustered counties with high and low cancer incidences in Texas.

RESULTS

Age-adjusted breast cancer incidence rate in the highest median income quintile group was 151.51 cases per 100,000 in 2008-2011 as compared to 98.95 cases per 100,000 in the lowest median income quintile group. The risk of colorectal cancer appeared to decrease with increasing median income in racial/ethnic population. Spatial analysis revealed the significant low breast cancer incidence cluster regions located in southwest US-Mexico border counties in Texas.

CONCLUSIONS

This study demonstrated that higher income was associated with an increased risk of breast cancer and a decreased risk of colorectal cancer in Texas. There were geographic variations with cancer incidence clustered in high risk areas in Texas. Future studies may need to explore more factors that might explain income and cancer risk associations and their geographic variations.

Screening Mammography in a Public Hospital Serving Predominantly African-American Women: A Stage-Survival-Cost Model

BACKGROUND

Ethnic and socioeconomic disparities pervade breast cancer patterns and outcomes. Mammography guidelines reflect the difficulty in optimizing mortality reduction and cost-effectiveness, with controversy still surrounding the 2009 U.S. Preventive Services Task Force (USPSTF) recommendations. This study simulates USPSTF and American Cancer Society (ACS) guidelines' effects on stage, survival, and cost of treatment in an urban public hospital.

METHODS

Charts of 274 women diagnosed with stage I, II, or III breast cancer (2008-2010) were reviewed. Published tumor doubling times were used to predict size at diagnosis under simulated screening guidelines. Stage distributions under ACS and USPSTF guidelines were compared with those observed. Cohort survival for observed and hypothetical scenarios was estimated using national statistics. Treatment costs by stage, calculated from Georgia Medicaid claims data, were similarly applied.

RESULTS

Mean age at diagnosis was 56 years. African Americans predominated (82.5%), with 96% publically insured or uninsured. Simulated stages at diagnosis significantly favored ACS guidelines (43.1% stage 1/38.3% stage 2/9.9% stage 3 vs. USPSTF 23.0%/53.3 %/15.0%), as did 5-year survival and cost of treatment relative to both observed and USPSTF-predicted schema (p<.0001). Following USPSTF guidelines predicted lower survival and additional costs.

CONCLUSIONS

Following ACS guidelines seems to lead to earlier diagnosis for low-income African-American women and increase 5-year survival with lower overall and breast-specific costs. The data suggest that adjusting screening practices for lower socioeconomic status, ethnic minority women may prove essential in addressing cancer disparities.

Secular trends, race, and geographic disparity of early-stage breast cancer incidence: 25 years of surveillance in Connecticut

OBJECTIVES

We considered changes in the geographic distribution of early stage breast cancer among White and non-White women while secular trends in lifestyle and health care were under way.

METHODS

We aggregated tumor registry and census data by age, race, place of residence, and year of diagnosis to evaluate rate variation across Connecticut census tracts between 1985 and 2009. Global and local cluster detection tests were completed.

RESULTS

Age-adjusted incidence rates increased by 2.71% and 0.44% per year for White and non-White women, respectively. Significant global clustering was identified during surveillance of these populations, but the elements of clustering differed between groups. Among White women, fewer local clusters were detected after 1985 to 1989, whereas clustering increased over time among non-White women.

CONCLUSIONS

Small-area variation of breast cancer incidence rates across time periods proved to be dynamic and race-specific. Incidence rates might have been affected by secular trends in lifestyle or health care. Single cross-sectional analyses might have confused our understanding of disease occurrence by not accounting for the social context in which patient preferences or provider capacity influence the numbers and locations of diagnosed cases. Serial analyses are recommended to identify "hot spots" where persistent geographic disparities in incidence occur.

The association of area-level social class and tobacco use with adverse breast cancer characteristics among white and black women: evidence from Maryland, 1992-2003

Background

In breast cancer, worse disease characteristics are associated with fewer social resources and black race. However, it is unknown whether social gradients have similar impact across race, and whether behaviors, including tobacco use, may explain a portion of the social gradient.

Methods

We modeled relationships between area-level social class, tobacco spending and tumor characteristics, using 50,062 white and black cases diagnosed from 1992–2003 in Maryland, a racially and economically diverse state on the east coast of the United States. Multi-level models estimated the effect of area-level social class and tobacco consumption on tumor grade, size, and stage at diagnosis.

Results

Adjusting for race, age and year of diagnosis, higher social class was associated with lower risk for tumors with histological grade 3 or 4 (O.R. 0.96, 95% C.I. 0.94,0.99), those diagnosed at SEER stage 2 or later (O.R. 0.89, 95% C.I. 0.86, 0.91), and tumor size >2 cm (O.R. 0.87, 95% C.I. 0.84, 0.90). Higher tobacco spending was associated with higher risk for higher grade (O.R. 1.01, 1.00, 1.03) and larger tumors (O.R. 1.03, 95% C.I. 1.01, 1.06), but was not statistically significantly related to later stage (O.R. 1.00, 95% C.I. 0.98, 1.02). Social class was less protective for black women, but tobacco effects were not race-specific.

Conclusions

Results suggest that in one U.S. geographic area, there is a differential protection from social class for black and white women, supporting use of intersectionality theory in breast cancer disparities investigations. Area-level tobacco consumption may capture cases’ direct use and second hand smoke exposure, but also may identify neighborhoods with excess cancer-related behavioral or environmental exposures, beyond those measured by social class. Given the growing global burden of both tobacco addiction and aggressive breast cancer, similar investigations across diverse geographic areas are warranted.

Prediagnostic self-assessed health and extent of social networks predict survival in older individuals with cancer: a population based cohort study

OBJECTIVES

To assess the association between social networks on survival after cancer diagnosis in a population-based sample of elderly Israelis (>60 yo) living in the community in 1985 and followed for up to 20 years.

MATERIALS AND METHODS

We conducted a historical prospective study, using baseline measurements from a 1985 survey of a representative sample of community-dwelling population. Five distinct social networks were defined using information regarding number and intensity of social contacts: traditional-family (reference category), friends and neighbors, narrow-family, diverse, and attenuated. Cancer was ascertained through the Israel Cancer Registry, and mortality through the Population Registry after 20 years of follow-up.

RESULTS

The final study population included 676 participants diagnosed with cancer after 1985. Persons in the diverse network showed a lower risk of death (HR=0.74, 95% CI: 0.56-0.98) after adjusting for age, sex, smoking and self-assessed health. On the other hand, poor self-rated health at baseline (HR=1.39, 95% CI: 1.10-1.74 poor vs. all other categories of self-assessed health) was associated with increased risk of death. After excluding cancers amenable to early detection (breast, prostate, and colon) a borderline significant decreased risk of death following a diagnosis of cancer (HR=0.72, 95% CI: 0.52-1.01) was found.

CONCLUSION

There is evidence of a significant protective association between diverse social networks present before a cancer diagnosis and survival after the onset of disease. Social support from a variety of sources may be an important element in improving cancer survival in older individuals.

The relationship between area poverty rate and site-specific cancer incidence in the United States

BACKGROUND

The relationship between socioeconomic status and cancer incidence in the United States has not traditionally been a focus of population-based cancer surveillance systems.

METHODS

Nearly 3 million tumors diagnosed between 2005 and 2009 from 16 states plus Los Angeles were assigned into 1 of 4 groupings based on the poverty rate of the residential census tract at time of diagnosis. The sex-specific risk ratio of the highest-to-lowest poverty category was measured using Poisson regression, adjusting for age and race, for 39 cancer sites.

RESULTS

For all sites combined, there was a negligible association between cancer incidence and poverty; however, 32 of 39 cancer sites showed a significant association with poverty (14 positively associated and 18 negatively associated). Nineteen of these sites had monotonic increases or decreases in risk across all 4 poverty categories. The sites most strongly associated with higher poverty were Kaposi sarcoma, larynx, cervix, penis, and liver; those most strongly associated with lower poverty were melanoma, thyroid, other nonepithelial skin, and testis. Sites associated with higher poverty had lower incidence and higher mortality than those associated with lower poverty.

CONCLUSIONS

These findings demonstrate the importance and relevance of including a measure of socioeconomic status in national cancer surveillance. Cancer 2014;120:2191–2198. © 2014 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society.

A majority of cancer sites exhibit significant associations with area poverty rates. Those associated with higher poverty had lower incidence but higher mortality than those associated with lower poverty.

Impact of neighborhood and individual socioeconomic status on survival after breast cancer varies by race/ethnicity: the Neighborhood and Breast Cancer Study

BACKGROUND

Research is limited on the independent and joint effects of individual- and neighborhood-level socioeconomic status (SES) on breast cancer survival across different racial/ethnic groups.

METHODS

We studied individual-level SES, measured by self-reported education, and a composite neighborhood SES (nSES) measure in females (1,068 non-Hispanic whites, 1,670 Hispanics, 993 African-Americans, and 674 Asian-Americans), ages 18 to 79 years and diagnosed 1995 to 2008, in the San Francisco Bay Area. We evaluated all-cause and breast cancer-specific survival using stage-stratified Cox proportional hazards models with cluster adjustment for census block groups.

RESULTS

In models adjusting for education and nSES, lower nSES was associated with worse all-cause survival among African-Americans (P trend = 0.03), Hispanics (P trend = 0.01), and Asian-Americans (P trend = 0.01). Education was not associated with all-cause survival. For breast cancer-specific survival, lower nSES was associated with poorer survival only among Asian-Americans (P trend = 0.01). When nSES and education were jointly considered, women with low education and low nSES had 1.4 to 2.7 times worse all-cause survival than women with high education and high nSES across all races/ethnicities. Among African-Americans and Asian-Americans, women with high education and low nSES had 1.6 to 1.9 times worse survival, respectively. For breast cancer-specific survival, joint associations were found only among Asian-Americans with worse survival for those with low nSES regardless of education.

CONCLUSIONS

Both neighborhood and individual SES are associated with survival after breast cancer diagnosis, but these relationships vary by race/ethnicity.

IMPACT

A better understanding of the relative contributions and interactions of SES with other factors will inform targeted interventions toward reducing long-standing disparities in breast cancer survival.

Neighborhood socio-economic disadvantage and race/ethnicity as predictors of breast cancer stage at diagnosis

BACKGROUND

This study investigated the role of key individual- and community-level determinants to explore persisting racial/ethnic disparities in breast cancer stage at diagnosis in California during 1990 and 2000.

METHODS

We examined socio-demographic determinants and changes in breast cancer stage at diagnosis in California during 1990 and 2000. In situ, local, regional, and distant diagnoses were examined by individual (age, race/ethnicity, and marital status) and community (income and education by zip code) characteristics. Community variables were constructed using the California Cancer Registry 1990-2000 and the 1990 and 2000 U.S. Census.

RESULTS

From 1990 to 2000, there was an overall increase in the percent of in situ diagnoses and a significant decrease in regional and distant diagnoses. Among white and Asian/Pacific Islander women, a significant percent increase was observed for in situ diagnoses, and significant decreases in regional and distant diagnoses. Black women had a significant decrease in distant -stage diagnoses, and Hispanic women showed no significant changes in any diagnosis during this time period. The percent increase of in situ cases diagnosed between 1990 and 2000 was observed even among zip codes with low income and education levels. We also found a significant percent decrease in distant cases for the quartiles with the most poverty and least education.

CONCLUSIONS

Hispanic women showed the least improvement in breast cancer stage at diagnosis from 1990 to 2000. Breast cancer screening and education programs that target under-served communities, such as the rapidly growing Hispanic population, are needed in California.

Educational differences in postmenopausal breast cancer--quantifying indirect effects through health behaviors, body mass index and reproductive patterns

Studying mechanisms underlying social inequality in postmenopausal breast cancer is important in order to develop prevention strategies. Standard methods for investigating indirect effects, by comparing crude models to adjusted, are often biased. We applied a new method enabling the decomposition of the effect of educational level on breast cancer incidence into indirect effects through reproductive patterns (parity and age at first birth), body mass index and health behavior (alcohol consumption, physical inactivity, and hormone therapy use). The study was based on a pooled cohort of 6 studies from the Copenhagen area including 33,562 women (1,733 breast cancer cases) aged 50-70 years at baseline. The crude absolute rate of breast cancer was 399 cases per 100,000 person-years. A high educational level compared to low was associated with 74 (95% CI 22-125) extra breast cancer cases per 100,000 person-years at risk. Of these, 26% (95% CI 14%-69%) could be attributed to alcohol consumption. Similar effects were observed for age at first birth (32%; 95% CI 10%-257%), parity (19%; 95%CI 10%-45%), and hormone therapy use (10%; 95% CI 6%-18%). Educational level modified the effect of physical activity on breast cancer. In conclusion, this analysis suggests that a substantial number of the excess postmenopausal breast cancer events among women with a high educational level compared to a low can be attributed to differences in alcohol consumption, use of hormone therapy, and reproductive patterns. Women of high educational level may be more vulnerable to physical inactivity compared to women of low educational level.

Adult cancers near high-voltage overhead power lines

BACKGROUND

Extremely low-frequency magnetic fields are designated as possibly carcinogenic in humans, based on an epidemiologic association with childhood leukemia. Evidence for associations with adult cancers is weaker and inconsistent.

METHODS

We conducted a case-control study to investigate risks of adult cancers in relation to distance and extremely low-frequency magnetic fields from high-voltage overhead power lines using National Cancer Registry Data in England and Wales, 1974-2008. The study included 7823 leukemia, 6781 brain/central nervous system cancers, 9153 malignant melanoma, 29,202 female breast cancer cases, and 79,507 controls frequency-matched on year and region (three controls per case except for female breast cancer, one control per case) 15-74 years of age living within 1000 m of a high-voltage overhead power line.

RESULTS

There were no clear patterns of excess risk with distance from power lines. After adjustment for confounders (age, sex [except breast cancer], deprivation, rurality), for distances closest to the power lines (0-49 m) compared with distances 600-1000 m, odds ratios (ORs) ranged from 0.82 (95% confidence interval = 0.61-1.11; 66 cases) for malignant melanoma to 1.22 (0.88-1.69) for brain/central nervous system cancer. We observed no meaningful excess risks and no trends of risk with magnetic field strength for the four cancers examined. In adjusted analyses at the highest estimated field strength, ≥1000 nanotesla (nT), compared with <100 nT, ORs ranged from 0.68 (0.39-1.17) for malignant melanoma to 1.08 (0.77-1.51) for female breast cancer.

CONCLUSION

Our results do not support an epidemiologic association of adult cancers with residential magnetic fields in proximity to high-voltage overhead power lines.

Who and what is a "population"? Historical debates, current controversies, and implications for understanding "population health" and rectifying health inequities

CONTEXT

The idea of "population" is core to the population sciences but is rarely defined except in statistical terms. Yet who and what defines and makes a population has everything to do with whether population means are meaningful or meaningless, with profound implications for work on population health and health inequities.

METHODS

In this article, I review the current conventional definitions of, and historical debates over, the meaning(s) of "population," trace back the contemporary emphasis on populations as statistical rather than substantive entities to Adolphe Quetelet's powerful astronomical metaphor, conceived in the 1830s, of l'homme moyen (the average man), and argue for an alternative definition of populations as relational beings. As informed by the ecosocial theory of disease distribution, I then analyze several case examples to explore the utility of critical population-informed thinking for research, knowledge, and policy involving population health and health inequities.

FINDINGS

Four propositions emerge: (1) the meaningfulness of means depends on how meaningfully the populations are defined in relation to the inherent intrinsic and extrinsic dynamic generative relationships by which they are constituted; (2) structured chance drives population distributions of health and entails conceptualizing health and disease, including biomarkers, as embodied phenotype and health inequities as historically contingent; (3) persons included in population health research are study participants, and the casual equation of this term with "study population" should be avoided; and (4) the conventional cleavage of "internal validity" and "generalizability" is misleading, since a meaningful choice of study participants must be in relation to the range of exposures experienced (or not) in the real-world societies, that is, meaningful populations, of which they are a part.

CONCLUSIONS

To improve conceptual clarity, causal inference, and action to promote health equity, population sciences need to expand and deepen their theorizing about who and what makes populations and their means.

A multi-ethnic breast cancer case-control study in New Zealand: evidence of differential risk patterns

PURPOSE

To investigate whether the relationships between established risk factors and breast cancer risk differ between three ethnic groups in New Zealand, namely Māori, Pacific, and non-Māori/non-Pacific women.

METHODS

The study is a multi-ethnic, age-, and ethnicity-matched population-based case-control study of breast cancer in women. Women with a primary, invasive breast cancer registered on the New Zealand Cancer Registry between 1 April 2005 and 30 April 2006, and Māori or Pacific women diagnosed to 30 April 2007 were eligible. Control women were identified from the New Zealand Electoral Roll, stratified by ethnicity, then frequency matched on age to the cases. Logistic regression was used to estimate odds ratios (OR) and 95 % confidence intervals (CI) between exposures and breast cancer risk in three ethnic groups separately. Likelihood ratio tests were used to test for modification of the effects by ethnicity. Post-stratification weighting of the controls was used to account for differential non-response by deprivation category.

RESULTS

The study comprised 1,799 cases (302 Māori, 70 Pacific, 1,427 non-Māori/non-Pacific) and 2,543 controls (746 Māori, 194 Pacific, 1,603 non-Māori/non-Pacific), based on self-identified ethnicity. Māori women were more likely to have ER and PR positive breast cancer compared to other ethnicities. There were marked differences in exposure prevalence between ethnicities and some differing patterns of risk factors for breast cancer between the three main ethnic groups. Of interest was the strong relationship between number of children and lower breast cancer risk in Pacific women (OR for 4 or more vs. 1 child OR 0.13, 95 % CI 0.05-0.35) and a higher risk of breast cancer associated with smoking (OR 1.76, 95 % CI 1.25-2.48) and binge drinking (5 or more vs. 1-2 drinks per occasion, OR 1.55, 95 % CI 1.07-2.26) in Māori women. Some of the documented results were attenuated following post-stratification weighting.

CONCLUSIONS

The findings of this study need to be interpreted with caution, given the possibility of selection bias due to low response rates among some groups of women. Reducing the burden of breast cancer in New Zealand is likely to require different approaches for different ethnic groups.

In vitro fertilization and breast cancer: is there cause for concern?

OBJECTIVE

To examine the incidence rate of breast cancer in a cohort of women undergoing treatment for infertility, comparing the rate in women who had in vitro fertilization (IVF) with those who did not.

DESIGN

Population-based cohort study using linked hospital and registry data.

SETTING

Hospital.

PATIENT(S)

All women aged 20-44 years seeking hospital investigation and treatment for infertility in Western Australia during the period 1983-2002 (n = 21,025).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Hazard ratios (HRs) for breast cancer.

RESULT(S)

There was no overall increase in the rate of breast cancer in women who had IVF (HR 1.10, 95% confidence interval [CI] 0.88-1.36), but there was an increased rate in women who commenced IVF at a young age. Women who commenced hospital infertility treatment at 24 years and required IVF had an unadjusted HR of breast cancer of 1.59 (95% CI 1.05-2.42) compared with women of the same age who had infertility treatment but no IVF. When adjusted for late age at first delivery, which is associated with an increased rate of breast cancer, and delivery of twins and higher-order multiples, which is associated with a decreased rate of breast cancer, the HR remained elevated at 1.56 (95% CI 1.01-2.40). Hazard ratios were not elevated in women who commenced treatment at age 40 and required IVF (adjusted HR 0.87, 95% CI 0.62-1.22).

CONCLUSION(S)

Commencing IVF treatment at a young age is associated with an increased rate of breast cancer.

Association of time since last birth, age at first birth and parity with breast cancer survival among parous women: a register-based study from Norway

Reproductive factors that have a well-documented effect on breast cancer risk may also influence the prognosis of the disease, but previous studies on breast cancer survival have yielded conflicting results. We combined information from two population-based registries and obtained information on 16,970 parous women with invasive breast cancer. Cox regression analysis was used to assess breast cancer survival in relation to age at diagnosis, age at first birth, time since last birth and parity. We stratified the analyses by age at diagnosis (<50 and ≥ 50 years) as an approximation for menopausal age. In women diagnosed before 50 years of age, breast cancer survival was reduced with younger age at diagnosis (p for trend <0.001), whereas in women diagnosed at 50 years or later, survival was reduced with older age at diagnosis (p for trend 0.011). For breast cancer diagnosed before 50 years, survival was poorer in women with four or more births compared to women with one or two births (hazard ratio 1.3, 95% confidence interval 1.1-1.6). A short time since last birth was associated with reduced survival (p for trend 0.05), but adjustment for stage and grade attenuated the association. Among women diagnosed at 50 years or later, we found no association with survival for any of the reproductive factors. In summary, reproductive factors were associated with survival from breast cancer diagnosed before but not after age 50 years. Young women had a particularly poor prognosis throughout the study period.

Disparities in breast cancer mortality trends in a middle income country

In recent decades, breast cancer cases have increased steadily worldwide. However, the increases do not hold across all demographics and breast cancer cases in low and middle income countries have increased much faster than the global trend. Colombia is not an exception. Breast cancer was the most frequent tumor and the second cause of cancer-related deaths in women in 2008, with an estimated of 6,700 new cases and 2,100 deaths. We present here an analysis of breast cancer mortality rates and trends in Colombia, over the period 1985-2008. We studied overall and age-specific changes in breast cancer mortality using change-point Poisson regression models. Between 1985 and 2008, there were 32,375 breast cancer deaths in women in Colombia. Breast cancer mortality increased since 1985, although the annual increase varied between age groups and socioeconomic levels. Only in women aged 45-64 years old that live in areas of high socioeconomic levels, breast cancer mortality was stable or decreasing. Hence, successful cancer control is possible in middle income countries, as shown by the progress observed in certain groups. The development of an integrated strategy of early detection and early access to proper treatment, suitable for areas with limited resources, is an urgent necessity.