The contribution of risk factors to the higher incidence of invasive and in situ breast cancers in women with higher levels of education in the European prospective investigation into cancer and nutrition

Socioeconomic Deprivation and Invasive Breast Cancer Incidence by Stage at Diagnosis: A Possible Explanation to the Breast Cancer Social Paradox

In this study, we assessed the influence of area-based socioeconomic deprivation on the incidence of invasive breast cancer (BC) in France, according to stage at diagnosis. All women from six mainland French departments, aged 15+ years, and diagnosed with a primary invasive breast carcinoma between 2008 and 2015 were included (n = 33,298). Area-based socioeconomic deprivation was determined using the French version of the European Deprivation Index. Age-standardized incidence rates (ASIR) by socioeconomic deprivation and stage at diagnosis were compared estimating incidence rate ratios (IRRs) adjusted for age at diagnosis and rurality of residence. Compared to the most affluent areas, significantly lower IRRs were found in the most deprived areas for all-stages (0.85, 95% CI 0.81-0.89), stage I (0.77, 95% CI 0.72-0.82), and stage II (0.84, 95% CI 0.78-0.90). On the contrary, for stages III-IV, significantly higher IRRs (1.18, 95% CI 1.08-1.29) were found in the most deprived areas. These findings provide a possible explanation to similar or higher mortality rates, despite overall lower incidence rates, observed in women living in more deprived areas when compared to their affluent counterparts. Socioeconomic inequalities in access to healthcare services, including screening, could be plausible explanations for this phenomenon, underlying the need for further research.

Causes and Risk Factors of Breast Cancer, What Do We Know for Sure? An Evidence Synthesis of Systematic Reviews and Meta-Analyses

Breast cancer affected more than 2.3 million women in 2022 and is the most diagnosed cancer among women worldwide. The incidence rates are greater in developed regions and are significantly higher among women with higher education and socioeconomic status. Therefore, it is reasonable to assume that the way women live their lives may impact their risk of being diagnosed with breast cancer. This systematic review aimed to identify what is known about the causes and risk factors of breast cancer, excluding genetic causes. A comprehensive systematic search identified 2387 systematic reviews, 122 were included and six overall themes identified. In our "top list" with the 36 most important findings, a study of breast density had the highest effect size for increasing the risk of breast cancer, and a high sex-hormone-binding globulin level was the most protective factor. Many of the included studies investigating the same topics had conflicting results. The conclusion from this evidence synthesis reveals a lack of consensus of factors associated with the causes and risk of breast cancer. These findings suggest that recommendations about lifestyle and breast cancer should be made with caution.

Controlling for polygenic genetic confounding in epidemiologic association studies

Epidemiologic associations estimated from observational data are often confounded by genetics due to pervasive pleiotropy among complex traits. Many studies either neglect genetic confounding altogether or rely on adjusting for polygenic scores (PGS) in regression analysis. In this study, we unveil that the commonly employed PGS approach is inadequate for removing genetic confounding due to measurement error and model misspecification. To tackle this challenge, we introduce PENGUIN, a principled framework for polygenic genetic confounding control based on variance component estimation. In addition, we present extensions of this approach that can estimate genetically-unconfounded associations using GWAS summary statistics alone as input and between multiple generations of study samples. Through simulations, we demonstrate superior statistical properties of PENGUIN compared to the existing approaches. Applying our method to multiple population cohorts, we reveal and remove substantial genetic confounding in the associations of educational attainment with various complex traits and between parental and offspring education. Our results show that PENGUIN is an effective solution for genetic confounding control in observational data analysis with broad applications in future epidemiologic association studies.

Socioeconomic and geographic disparities of breast cancer incidence according to stage at diagnosis in France

PURPOSE

Low socioeconomic background (SB) has been associated with lower breast cancer (BC) incidence and higher BC mortality. One explanation of this paradox is the higher frequency of advanced BC observed in deprived women. However, it is still unclear if SB affects similarly BC incidence. This study investigated the link between SB and early/advanced BC incidence from Loire-Atlantique/Vendee Cancer registry data (France).

MATERIALS AND METHODS

Fourteen thousand three hundred fifty three women living in the geographic area covered by the registry and diagnosed with a primary BC in 2008-2015 were included. SB was approached by a combination of two ecological indexes (French European Deprivation Index and urban/rural residence place). Mixed effects logistic and Poisson regressions were used, respectively, to estimate the odds of advanced (stage ≥ II) BC and the ratio of incidence rates of early (stage 0-I) and advanced BC according to SB, overall and by age group (< 50, 50-74, ≥ 75).

RESULTS

Compared to women living in affluent-urban areas, women living in deprived-urban and deprived-rural areas had a higher proportion of advanced BC [respectively, OR = 1.11 (1.01-1.22), OR = 1.60 (1.25-2.06)] and lower overall (from - 6 to - 15%) and early (from - 9 to - 31%) BC incidences rates Advanced BC incidence rates were not influenced by SB. These patterns were similar in women under 75 years, especially in women living in deprived-rural areas. In the elderly, no association between SB and BC frequency/incidence rates by stage was found.

CONCLUSION

Although advanced BC was more frequent in women living in deprived and rural areas, SB did not influence advanced BC incidence. Therefore, differences observed in overall BC incidence according to SB were only due to higher incidence of early BC in affluent and urban areas. Future research should confirm these results in other French areas.

Exposure to pesticides and breast cancer in the city of Petrópolis, Brazil

To investigate the association between pesticide use and breast cancer. A hospital-based case-control study was conducted in Petrópolis city, Brazil. The study data were obtained through interviews, and the magnitude of the association between self-reported pesticide exposure and breast cancer was determined using unconditional logistic regression. A higher estimated risk for breast cancer was found in women exposed to pesticides for 10 or more years, where this association was not statistically significant after adjusting for potential confounders (OR = 1.40; 95% CI 0.85-2.49). A positive statistically significant association was found between breast cancer and higher educational level or previous use of hormone replacement therapy (HRT), whereas having had 2 or more pregnancies to term proved a protective factor. Further studies elucidating the contribution of pesticide exposure to the development of breast cancer are needed, given that current findings in the literature are conflicting.

Identify factors for insufficient (> 2 yr) mammogram screening among Oregonian women

PURPOSE

Women with breast cancer diagnosed from mammogram screenings have a lower mortality risk than women diagnosed from symptoms. Currently, the U.S Preventive Services Task Force recommends biannual screening for women aged 50-74 years old. In this study, we aimed to identify factors associated with inadequate screening defined as "no mammogram screening within past 2 years" to guide cancer prevention and early detection efforts.

METHODS

This study utilized area-based probabilistic sampling survey data, collected across Oregon in 2019. Dataset weights were calculated using a raking approach. Demographic and behavior information were collected with existing validated questionnaire items from national surveys. Weighted multivariable logistic regression analyses with missing-value imputations were conducted to identify factors associated with inadequate mammogram screening.

RESULTS

The study included 254 women 50-74 years old without previous breast or ovarian cancer history. 19.29% of the sample reported no mammogram within two years, including 1.57% with no previous mammograms. Following unadjusted analyses, the significant factors included education, occupation status, health insurance and smoking and were therefore included into the adjusted model. In the multivariate adjusted model education remained significant while occupation status, health insurance and smoking were no longer significant. Compared to women with a college graduate degree, women with less than college graduate degree were at higher risk of inadequate screening [OR (95% CI) = 3.23 (1.54, 6.74)].

CONCLUSIONS

Lack of education was significantly associated with inadequate mammogram screening even after adjusting for occupation status, health insurance and smoking, which should prompt further outreach and education.

Lipids, Anthropometric Measures, Smoking and Physical Activity Mediate the Causal Pathway From Education to Breast Cancer in Women: A Mendelian Randomization Study

Purpose

We aimed to investigate whether obtaining a higher level of education was causally associated with lower breast cancer risk and to identify the causal mechanism linking them.

Methods

The main data analysis used publicly available summary-level data from 2 large genome-wide association study consortia. Mendelian randomization (MR) analysis used 65 genetic variants derived from the Social Science Genetic Association Consortium as instrumental variables for years of schooling. The outcomes from the Breast Cancer Association Consortium (BCAC) were the overall breast cancer risk (122,977 cases/105,974 controls in women) and the two subtypes: estrogen receptor (ER)-positive breast cancer and ER-negative breast cancer. Fixed and random effects inverse variance weighted methods were used to estimate the causal effects, along with other additional MR methods for sensitivity analyses.

Results

Results showed that each additional standard deviation of 4.2 years of education was causally associated with a 27% lower risk of ER-negative breast cancer (odds ratio, 0.73; 95% confidence interval, 0.64–0.84; p-value < 0.001). This finding was consistent with the results of the sensitivity analyses. Physical activities can help improve the protective effect of education against breast cancer, with relatively large mediation proportions. Education increases the risk of ER-positive breast cancer due to alterations in high-density lipoprotein level, triglyceride level, height, waist-to-hip ratio, body mass index, and smoking status, with relative medium mediation proportions. Other mediators including low-density lipoprotein, hip circumference, number of cigarettes smoked per day, time spent performing light physical activity, and performing vigorous physical activity for > 10 minutes explain a small part of the causal effect of education on the risk of developing breast cancer, and their mediation proportion is approximately 1%.

Conclusion

A low level of education is a causal risk factor in the development of breast cancer as it is associated with poor lipid profile, obesity, smoking, and types of physical activity.

Breast Cancer Characteristics in the Population of Survivors Participating in the World Trade Center Environmental Health Center Program 2002-2019

The destruction of World Trade Center on 11 September 2001 exposed local community members to a complex mixture of known carcinogens and potentially carcinogenic substances. To date, breast cancer has not been characterized in detail in the WTC-exposed civilian populations. The cancer characteristics of breast cancer patients were derived from the newly developed Pan-Cancer Database at the WTC Environmental Health Center (WTC EHC). We used the Surveillance, Epidemiology, and End Results (SEER) Program breast cancer data as a reference source. Between May 2002 and 31 December 2019, 2840 persons were diagnosed with any type of cancer at the WTC EHC, including 601 patients with a primary breast cancer diagnosis (592 women and 9 men). There was a higher proportion of grade 3 (poorly differentiated) tumors (34%) among the WTC EHC female breast cancers compared to that of the SEER-18 data (25%). Compared to that of the SEER data, female breast cancers in the WTC EHC had a lower proportion of luminal A (88% and 65%, respectively), higher proportion of luminal B (13% and 15%, respectively), and HER-2-enriched (5.5% and 7%, respectively) subtypes. These findings suggest considerable differences in the breast cancer characteristics and distribution of breast cancer intrinsic subtypes in the WTC-exposed civilian population compared to that of the general population. This is important because of the known effect of molecular subtypes on breast cancer prognosis.

Examining the etiology of early-onset breast cancer in the Canadian Partnership for Tomorrow's Health (CanPath)

PURPOSE

Breast cancer incidence among younger women (under age 50) has increased over the past 25 years, yet little is known about the etiology among this age group. The objective of this study was to investigate relationships between modifiable and non-modifiable risk factors and early-onset breast cancer among three prospective Canadian cohorts.

METHODS

A matched case-control study was conducted using data from Alberta's Tomorrow Project, BC Generations Project, and the Ontario Health Study. Participants diagnosed with breast cancer before age 50 were identified through provincial registries and matched to three control participants of similar age and follow-up. Conditional logistic regression was used to examine the association between factors and risk of early-onset breast cancer.

RESULTS

In total, 609 cases and 1,827 controls were included. A body mass index ≥ 30 kg/m² was associated with a lower risk of early-onset breast cancer (OR 0.65; 95% CI 0.47-0.90), while a waist circumference ≥ 88 cm was associated with an increased risk (OR 1.58; 95% CI 1.18-2.11). A reduced risk was found for women with ≥ 2 pregnancies (OR 0.76; 95% CI 0.59-0.99) and a first-degree family history of breast cancer was associated with an increased risk (OR 1.95; 95% CI 1.47-2.57).

CONCLUSIONS

In this study, measures of adiposity, pregnancy history, and familial history of breast cancer are important risk factors for early-onset breast cancer. Evidence was insufficient to conclude if smoking, alcohol intake, fruit and vegetable consumption, and physical activity are meaningful risk factors. The results of this study could inform targeted primary and secondary prevention for early-onset breast cancer.

Pertussis in Individuals with Co-morbidities: A Systematic Review

Pertussis is a highly contagious disease of the respiratory tract caused by Bordetella pertussis. Although the burden of pertussis is highest in children, available data suggests that pertussis in the elderly and those with underlying chronic conditions or illnesses can result in significant morbidity, mortality and costs. We undertook a comprehensive review to assess the association between pertussis and chronic conditions/illnesses. A search was undertaken on 17 June 2019 across EMBASE, Medline and BIOSIS. Citations were limited to those in English, in humans and published since 1 January 1990. There were 1179 papers identified with an additional 70 identified through a review of the reference lists. Of these, 34 met the inclusion criteria. Papers included were categorised in groups, those which reported: associations between prior pertussis and subsequent chronic conditions or illnesses; a link between chronic conditions/illnesses and subsequent risk of pertussis; and those which reported on the effect of the chronic conditions/illnesses on pertussis complications or exacerbations. Pertussis appears to increase the likelihood of developing some chronic conditions/illnesses, but also appears to decrease the likelihood of developing some haematological cancers. There were several chronic conditions/illnesses where the study results were mixed, and several studies that found no association with previous pertussis. There were also studies which showed that having some comorbid health condition(s) might increase the risk of developing pertussis. Three studies showed pertussis can lead to increased exacerbations of chronic conditions/illnesses and associated hospitalisations, although one study showed it reduced the effects of chronic bronchitis. Previous pertussis appears to contribute to the increased likelihood of developing some respiratory conditions like asthma, and conversely those with asthma or COPD are at increased risk of severe pertussis requiring further intervention. Further research is required to confirm or disprove these associations, and to characterise the pathophysiological mechanisms behind the potential associations with pertussis.

Socio-Economic Position, Cancer Incidence and Stage at Diagnosis: A Nationwide Cohort Study in Belgium

Background: Socio-economic position is associated with cancer incidence, but the direction and magnitude of this relationship differs across cancer types, geographical regions, and socio-economic parameters. In this nationwide cohort study, we evaluated the association between different individual-level socio-economic and -demographic factors, cancer incidence, and stage at diagnosis in Belgium. Methods: The 2001 census was linked to the nationwide Belgian Cancer Registry for cancer diagnoses between 2004 and 2013. Socio-economic parameters included education level, household composition, and housing conditions. Incidence rate ratios were assessed through Poisson regression models. Stage-specific analyses were conducted through logistic regression models. Results: Deprived groups showed higher risks for lung cancer and head and neck cancers, whereas an inverse relation was observed for malignant melanoma and female breast cancer. Typically, associations were more pronounced in men than in women. A lower socio-economic position was associated with reduced chances of being diagnosed with known or early stage at diagnosis; the strongest disparities were found for male lung cancer and female breast cancer. Conclusions: This study identified population groups at increased risk of cancer and unknown or advanced stage at diagnosis in Belgium. Further investigation is needed to build a comprehensive picture of socio-economic inequality in cancer incidence.

Early-Life Risk Factors for Breast Cancer - Prospective Follow-up in the Northern Finland Birth Cohort 1966

BACKGROUND

While some risk factors for breast cancer have been confirmed, less is known about the role of early biological and social risk factors for breast cancer in adult life.

METHODS

In a prospective follow-up in the Northern Finland Birth Cohort 1966 consisting of 5,308 women, 120 breast cancers were reported via national registers by the end of 2018. Early risk factors were examined with univariate and multivariate analyses using Cox regression analysis. The main results are reported with HRs and their 95% confidence intervals (CI).

RESULTS

In the multivariate-adjusted models, women whose mothers lived in urban areas (HR, 1.68; 95% CI, 1.13-2.51) during pregnancy, were low educated (HR, 2.40; 95% CI, 1.30-4.45), and had been diagnosed with breast cancer (HR, 1.97; 95% CI, 1.09-3.58) had a higher risk for breast cancer in adult life. Lower BMI at the age of 14 associated nonsignificantly with the risk of breast cancer (Mann-Whitney U test, P = 0.087). No association between birth size and breast cancer risk in adult life was found.

CONCLUSIONS

Early-life residence and socioeconomic conditions may have an impact on developing breast cancer in women in adult life. All breast cancer cases of this study were relatively young, and most of them are assumed to be premenopausal.

IMPACT

This study is one of a few prospective birth cohort studies to examine early-life socioeconomic factors and breast cancer risk in adult life. This study is limited due to small number of cases.

Education level and breast cancer incidence: a meta-analysis of cohort studies

OBJECTIVE

We aimed to examine the association between education level and breast cancer incidence by a meta-analysis of cohort studies.

METHODS

Relevant studies were identified by searching PubMed, Web of Science, and Scopus databases on June 10, 2018. Reference lists from the obtained articles were also reviewed. We included cohort studies reporting relative risks with 95% CIs for the association between education level and breast cancer incidence. Either a fixed- or random-effects model was used to calculate the pooled risk estimates.

RESULTS

We identified 18 cohort studies with more than 10 million women. Compared with women with a lower education level, women with a higher education level had a significantly higher risk of developing breast cancer (pooled relative risk 1.22 [95% CI, 1.14-1.30]). The results did not differ by study area or reference group. The association remained in studies that adjusted for age at first birth and parity, but was attenuated and no longer significant when the analysis was restricted to studies that adjusted for alcohol use, to studies that adjusted for age at menopause, or to studies that adjusted for hormone therapy.

CONCLUSIONS

A higher education level may be associated with an increased risk of developing breast cancer, in which alcohol use, age at menopause, and hormone therapy may, at least partially, play a mediating role.

The impact of lifecourse socio-economic position and individual social mobility on breast cancer risk

BACKGROUND

Women with an advantaged socioeconomic position (SEP) have a higher risk of developing breast cancer (BC). The reasons for this association do not seem to be limited to reproductive factors and remain to be understood. We aimed to investigate the impact of lifecourse SEP from childhood and social mobility on the risk of BC considering a broad set of potential mediators.

METHODS

We used a discovery-replication strategy in two European prospective cohorts, E3N (N = 83,436) and EPIC-Italy (N = 20,530). In E3N, 7877 women were diagnosed with BC during a median 24.4 years of follow-up, while in EPIC-Italy, 893 BC cases were diagnosed within 15.1 years. Hazard ratios (HR) were estimated using Cox proportional hazard models on imputed data.

RESULTS

In E3N, women with higher education had a higher risk of BC (HR [95%CI] = 1.21 [1.12, 1.30]). This association was attenuated by adjusting for reproductive factors, in particular age at first childbirth (HR[95%CI] = 1.13 [1.04, 1.22]). Health behaviours, anthropometric variables, and BC screening had a weaker effect on the association. Women who remained in a stable advantaged SEP had a higher risk of BC (HR [95%CI] = 1.24 [1.07; 1.43]) attenuated after adjustment for potential mediators (HR [95%CI] = 1.13 [0.98; 1.31]). These results were replicated in EPIC-Italy.

CONCLUSIONS

These results confirm the important role of reproductive factors in the social gradient in BC risk, which does not appear to be fully explained by the large set of potential mediators, including cancer screening, suggesting that further research is needed to identify additional mechanisms.

Workforce participation of Australian women with breast cancer

OBJECTIVE

International research suggests that many women do not return to their previous work after breast cancer. This study aimed to identify workforce participation patterns for Australian women with breast cancer and compare these to healthy aged matched women.

METHODS

Using the 1946-1951 birth cohort of the Australian Longitudinal Study on Women's Health, the work status of women was compared three years before and three years after their first reported breast cancer diagnosis. Latent class analysis was used to identify workforce participation patterns of women with breast cancer and healthy aged matched women. Multinomial logistic regression examined associations between work patterns and other risk factors.

RESULTS

Pre and post breast cancer diagnosis work status data were available for 448 women with breast cancer between 1998 and 2010. Three years after diagnosis, 48% of full-time workers returned to full-time work but 52% returned to part time work or were not in paid work. Latent class analysis identified five classes. Women with breast cancer were more likely to be in the 'mostly full-time work' and 'mostly not in paid work' classes compared to healthy women. Odds ratios showed that women in remote areas, partnered, with less education or with chronic health condition were more likely to be 'not in paid work'.

CONCLUSION

Breast cancer has a negative impact on the workforce participation of Australian women. Women with breast cancer need support to return to work.

Socioeconomic inequalities in cancer incidence in Europe: a comprehensive review of population-based epidemiological studies

Background

Since the end of the previous century, there has not been a comprehensive review of European studies on socioeconomic inequality in cancer incidence. In view of recent advances in data source linkage and analytical methods, we aimed to update the knowledge base on associations between location-specific cancer incidence and individual or area-level measures of socio-economic status (SES) among European adults.

Materials and methods

We systematically searched three databases (PubMed, Scopus and Web of Science) for articles on cancer incidence and SES. Qualitative synthesis was performed on the 91 included English language studies, published between 2000 and 2019 in Europe, which focused on adults, relied on cancer registry data and reported on relative risk (RR) estimates.

Results

Adults with low SES have increased risk of head and neck, oesophagogastric, liver and gallbladder, pancreatic, lung, kidney, bladder, penile and cervical cancers (highest RRs for lung, head and neck, stomach and cervix). Conversely, high SES is linked with increased risk of thyroid, breast, prostate and skin cancers. Central nervous system and haematological cancers are not associated with SES. The positive gap in testicular cancer has narrowed, while colorectal cancer shows a varying pattern in different countries. Negative associations are generally stronger for men compared to women.

Conclusions

In Europe, cancers in almost all common locations are associated with SES and the inequalities can be explained to a varying degree by known life-style related factors, most notably smoking. Independent effects of many individual and area SES measures which capture different aspects of SES can also be observed.

What Explains Education Disparities in Screening Mammography in the United States? A Comparison with The Netherlands

Background: In the U.S., less educated women are substantially less likely to receive screening mammography. It is not clear whether this is due to differences in access to screening or in perceptions of breast cancer risks and the effectiveness of screening. We weigh the plausibility of these two explanations by examining how the dependence of mammography on education changes after conditioning on indicators of access and perceptions. We also compare estimates for the U.S. with those for the Netherlands where there is universal access to a publicly financed screening program. Method: Cross-sectional and cross-country comparable individual level data from the American Life Panel (n = 646) and the Netherlands Longitudinal Internet Studies for the Social Sciences (n = 1398) were used to estimate and explain education disparities in screening mammograms given to American and Dutch women aged 40+. The education gradient was estimated using logit models. Controls were sequentially added to detect whether disparities were explained by differences in access or perceptions of risks and effectiveness. Results: In the United States, high school graduates were 11.5 percentage points (95% CI: 1–22 percentage points) less likely than college graduates to receive a screening mammogram in the previous two years. This education gradient was largely explained by differences in income, insurance coverage and receipt of medical advice. It was not explained by educational differences in the perceived risk of breast cancer and the effectiveness of mammography. There were no education disparities in receipt of mammography among Dutch women within the 50–75 age range covered by the national screening program. Conclusion: In the absence of a universal screening program in the U.S., determinants of access—income, insurance coverage and receipt of medical advice—appear to drive the education disparities in screening mammography.

A scoping review on the field validation and implementation of rapid diagnostic tests for vector-borne and other infectious diseases of poverty in urban areas

BACKGROUND

Health personnel face challenges in diagnosing vector-borne and other diseases of poverty in urban settings. There is a need to know what rapid diagnostic technologies are available, have been properly assessed, and are being implemented to improve control of these diseases in the urban context. This paper characterizes evidence on the field validation and implementation in urban areas of rapid diagnostics for vector-borne diseases and other diseases of poverty.

MAIN BODY

A scoping review was conducted. Peer-reviewed and grey literature were searched using terms describing the targeted infectious diseases, diagnostics evaluations, rapid tests, and urban setting. The review was limited to studies published between 2000 and 2016 in English, Spanish, French, and Portuguese. Inclusion and exclusion criteria were refined post hoc to identify relevant literature regardless of study design and geography. A total of 179 documents of the 7806 initially screened were included in the analysis. Malaria (n = 100) and tuberculosis (n = 47) accounted for the majority of studies that reported diagnostics performance, impact, and implementation outcomes. Fewer studies, assessing mainly performance, were identified for visceral leishmaniasis (n = 9), filariasis and leptospirosis (each n = 5), enteric fever and schistosomiasis (each n = 3), dengue and leprosy (each n = 2), and Chagas disease, human African trypanosomiasis, and cholera (each n = 1). Reported sensitivity of rapid tests was variable depending on several factors. Overall, specificities were high (> 80%), except for schistosomiasis and cholera. Impact and implementation outcomes, mainly acceptability and cost, followed by adoption, feasibility, and sustainability of rapid tests are being evaluated in the field. Challenges to implementing rapid tests range from cultural to technical and administrative issues.

CONCLUSIONS

Rapid diagnostic tests for vector-borne and other diseases of poverty are being used in the urban context with demonstrated impact on case detection. However, most evidence comes from malaria rapid diagnostics, with variable results. While rapid tests for tuberculosis and visceral leishmaniasis require further implementation studies, more evidence on performance of current tests or development of new alternatives is needed for dengue, Chagas disease, filariasis, leptospirosis, enteric fever, human African trypanosomiasis, schistosomiasis and cholera.

Changing patterns of breast cancer incidence and mortality by education level over four decades in Norway, 1971-2009

Background

In the last century, breast cancer incidence and mortality was higher among higher versus lower educated women in developed countries. Post-millennium, incidence rates have flattened off and mortality declined. We examined breast cancer trends by education level, to see whether recent improvements in incidence and mortality rates have occurred in all education groups.

Methods

We linked individual registry data on female Norwegian inhabitants aged 35 years and over during 1971–2009. Using Poisson models, we calculated absolute and relative educational differences in age-standardised breast cancer incidence and mortality over four decades. We estimated educational differences by Slope and Relative Index of Inequality, which correspond to rate difference and rate ratio, comparing the highest to lowest educated women.

Results

Pre-millennium, incidence and mortality of breast cancer were significantly higher in higher versus lower educated women. Post-millennium, educational differences in breast cancer incidence and mortality attenuated. During 2000–2009, breast cancer incidence was still 38% higher for higher versus lower educated women (Relative Index of Inequality: 1.38, 95% confidence interval: 1.31–1.44), but mortality no longer varied significantly by education level (Relative Index of Inequality: 1.09, 95% confidence interval: 0.99–1.19). Among women below 50 years, however, the education gradient for mortality reversed, and mortality was 28% lower for the highest versus lowest educated women during 2000–2009 (Relative Index of Inequality: 0.72, 95% confidence interval: 0.51–0.93).

Results

Post-millennium improvements in breast cancer incidence and mortality have primarily benefited higher educated women. Breast cancer mortality is now highest among the lowest educated women below 50 years.

Social determinants of breast cancer in the Caribbean: a systematic review

BACKGROUND

Breast cancer is the leading cause of cancer deaths among women in the Caribbean and accounts for >1 million disability adjusted life years. Little is known about the social inequalities of this disease in the Caribbean. In support of the Rio Political Declaration on addressing health inequities, this article presents a systematic review of evidence on the distribution, by social determinants, of breast cancer risk factors, frequency, and adverse outcomes in Caribbean women.

METHODS

MEDLINE, EMBASE, SciELO, CINAHL, CUMED, LILACS, and IBECS were searched for observational studies reporting associations between social determinants and breast cancer risk factors, frequency, or outcomes. Based on the PROGRESS-plus checklist, we considered 8 social determinant groups for 14 breast cancer endpoints, which totalled to 189 possible ways ('relationship groups') to explore the role of social determinants on breast cancer. Studies with >50 participants conducted in Caribbean territories between 2004 and 2014 were eligible for inclusion. The review was conducted according to STROBE and PRISMA guidelines and results were planned as a narrative synthesis, with meta-analysis if possible.

RESULTS

Thirty-four articles were included from 5,190 screened citations. From these included studies, 75 inequality relationships were reported examining 30 distinct relationship groups, leaving 84% of relationship groups unexplored. Most inequality relationships were reported for risk factors, particularly alcohol and overweight/obesity which generally showed a positive relationship with indicators of lower socioeconomic position. Evidence for breast cancer frequency and outcomes was scarce. Unmarried women tended to have a higher likelihood of being diagnosed with breast cancer when compared to married women. While no association was observed between breast cancer frequency and ethnicity, mortality from breast cancer was shown to be slightly higher among Asian-Indian compared to African-descent populations in Trinidad (OR 1.2, 95% CI 1.1-1.4) and Guyana (OR 1.3, 95% CI 1.0-1.6).

CONCLUSION

Study quantity, quality, and variability in outcomes and reporting limited the synthesis of evidence on the role of social determinants on breast cancer in the Caribbean. This report represents important current evidence on the region, and can guide future research priorities for better describing and understanding of Caribbean breast cancer inequalities.

Racial/Ethnic Differences in the Impact of Neighborhood Social and Built Environment on Breast Cancer Risk: The Neighborhoods and Breast Cancer Study

Background: Neighborhood socioeconomic status (nSES) has been found to be associated with breast cancer risk. It remains unclear whether this association applies across racial/ethnic groups independent of individual-level factors and is attributable to other neighborhood characteristics.Methods: We examined the independent and joint associations of education and nSES with odds of breast cancer. Residential addresses were geocoded for 2,838 cases and 3,117 controls and linked to nSES and social and built environment characteristics. We estimated ORs and 95% confidence intervals (CI) using multilevel logistic regression controlling for individual-level breast cancer risk factors and assessed the extent to which nSES associations were due to neighborhood characteristics.Results: Women living in the highest versus lowest nSES quintile had a nearly 2-fold greater odds of breast cancer, with elevated odds (adjusted ORs, 95% CI) for non-Hispanic whites (NHWs; 2.27; 1.45-3.56), African Americans (1.74; 1.07-2.83), U.S.-born Hispanics (1.82; 1.19-2.79), and foreign-born Hispanics (1.83; 1.06-3.17). Considering education and nSES jointly, ORs were increased for low education/high nSES NHWs (1.83; 1.14-2.95), high education/high nSES NHWs (1.64; 1.06-2.54), and high education/high nSES foreign-born Hispanics (2.17; 1.52-3.09) relative to their race/ethnicity/nativity-specific low education/low nSES counterparts. Adjustment for urban and mixed-land use characteristics attenuated the nSES associations for most racial/ethnic/nativity groups except NHWs.Conclusions: Our study provides empirical evidence for a role of neighborhood environments in breast cancer risk, specifically social and built environment attributes.Impact: Considering the role of neighborhood characteristics among diverse populations may offer insights to understand racial/ethnic disparities in breast cancer risk. Cancer Epidemiol Biomarkers Prev; 26(4); 541-52. ©2017 AACR.

Increased breast cancer mortality only in the lower education group: age-period-cohort effect in breast cancer mortality by educational level in South Korea, 1983-2012

BACKGROUND

A steadily increasing pattern of breast cancer mortality has been reported in South Korea since the late 1980s. This paper explored the trends of educational inequalities of female breast cancer mortality between 1983 and 2012 in Korea, and conducted age-period-cohort (APC) analysis by educational level.

METHODS

Age-standardized mortality rates of breast cancer per 100,000 person-years were calculated. Relative index of inequality (RII) for breast cancer mortality was used as an inequality measure. APC analyses were conducted using the Web tool for APC analysis provided by the Division of Cancer Epidemiology and Genetics at the U.S. National Cancer Institute.

RESULTS

An increasing trend in breast cancer mortality among Korean women between 1983 and 2012 was due to the increased mortality of the lower education groups (i.e., no formal education or primary education and secondary education groups), not the highest education group. The breast cancer mortality was higher in women with a tertiary education than in women with no education or a primary education during 1983-1992, and the reverse was true in 1993-2012. Consequently, RII was changed from positive to negative associations in the early 2000s. The lower education groups had the increased breast cancer mortality and significant cohort and period effects between 1983 and 2012, whereas the highest group did not.

CONCLUSIONS

APC analysis by socioeconomic position used in this study could provide an important clue for the causes on breast cancer mortality. The long-term monitoring of socioeconomic patterning in breast cancer risk factors is urgently needed.

The impacts of public mammography screening on the relationship between socioeconomic status and cancer stage

This study aimed to investigate the relationship between socioeconomic inequality and mortality following the introduction of a public mammography screening program in Norway by exploring the role of change in stage distribution as the mechanism for differences before and after the introduction of the screening program. Attained education level was used as a measure of socioeconomic status in this population-based study. All women aged 50–69 years diagnosed with breast cancer from 1999–2008 and with follow-up data until the end of 2009 were included. The primary endpoint was all-cause mortality. The results of a mediation analysis indicated that the introduction of screening led to stage distribution related reductions of −5.6 (95% confidence interval = −6.7 to −4.5), −2.5 (−3.0 to −2.1), and −1.4 (−1.9 to −0.9) fewer deaths per 1000 women for with a primary school education, secondary school education, and university education, respectively. The study showed that stage distribution explained −5 (−5.9 to −4.1) fewer deaths among women with a university education and −2.4 (−2.9 to −2.0) fewer deaths among women with a secondary school education before program implementation when compared to the group with a primary school education. There were significant reductions in mortality due to stage distribution after program implementation with differences relative to women with primary school of −1.8 (−2.2 to −1.4) and −0.7 (−0.9 to −0.5) fewer deaths in favor of women with university education and secondary school, respectively. The results indicate reduced importance of cancer stage as a reason for differences in mortality by socioeconomic status after the introduction of a public mammography program.

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The effects of breast cancer screening on socioeconomic inequality in survival are unknown.

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Stage and socioeconomic status in relation to the introduction of a screening program was examined.

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Mortality differences due to stage distribution were reduced after program implementation.

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Socioeconomic status by stage may be less important after screening introduction.

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.

Quantifying the mediating effects of smoking and occupational exposures in the relation between education and lung cancer: the ICARE study

Smoking only partly explains the higher lung cancer incidence observed among socially deprived people. Occupational exposures may account for part of these inequalities, but this issue has been little investigated. We investigated the extent to which smoking and occupational exposures to asbestos, silica and diesel motor exhaust mediated the association between education and lung cancer incidence in men. We analyzed data from a large French population-based case-control study (1976 lung cancers, 2648 controls). Detailed information on lifelong tobacco consumption and occupational exposures to various carcinogens was collected. We conducted inverse probability-weighted marginal structural models. A strong association was observed between education and lung cancer. The indirect effect through smoking varied by educational level, with the strongest indirect effect observed for those with the lowest education (OR = 1.34 (1.14-1.57)). The indirect effect through occupational exposures was substantial among men with primary (OR = 1.22 (1.15-1.30) for asbestos and silica) or vocational secondary education (OR = 1.18 (1.12-1.25)). The contribution of smoking to educational differences in lung cancer incidence ranged from 22 % (10-34) for men with primary education to 31 % (-3 to 84) for men with a high school degree. The contribution of occupational exposures to asbestos and silica ranged from 15 % (10-20) for men with a high school degree to 20 % (13-28) for men with vocational secondary education. Our results highlight the urgent need for public health policies that aim at decreasing exposure to carcinogens at work, in addition to tobacco control policies, if we want to reduce socioeconomic inequalities in the cancer field.

Socioeconomic disparities in breast cancer incidence and survival among parous women: findings from a population-based cohort, 1964-2008

Background

Socioeconomic position (SEP) has been associated with breast cancer incidence and survival. We examined the associations between two socioeconomic indicators and long-term breast cancer incidence and survival in a population-based cohort of parous women.

Methods

Residents of Jerusalem who gave birth between 1964–1976 (n = 40,586) were linked to the Israel Cancer Registry and Israel Population Registry to determine breast cancer incidence and vital status through mid-2008. SEP was assessed by husband’s occupation and the woman’s education. We used log ranks tests to compare incidence and survival curves by SEP, and Cox proportional hazard models to adjust for demographic, reproductive and diagnostic factors and assess effect modification by ethnic origin.

Results

In multivariable models, women of high SEP had a greater risk of breast cancer compared to women of low SEP (Occupation: HR 1.18, 95 % CI 1.03-1.35; Education: HR 1.39, 95 % CI 1.21-1.60) and women of low SEP had a greater risk of mortality after a breast cancer diagnosis (Occupation: HR 1.33, 95 % CI 1.04-1.70; Education: HR 1.37, 95 % CI 1.06-1.76). The association between education and survival was modified by ethnic origin, with a gradient effect observed only among women of European origin. Women of Asian, North African and Israeli origin showed no such trend.

Conclusions

SEP was associated with long-term breast cancer incidence and survival among Israeli Jews. Education had a stronger effect on breast cancer outcomes than occupation, suggesting that a behavioral mechanism may underlie disparities. More research is needed to explain the difference in the effect of education on survival among European women compared to women of other ethnicities.

Assessment of midwifery student preparation for performing the role of breast cancer educator

PURPOSE

Our research project aimed at presenting midwifery student self-assessment of performing the role of breast cancer prevention educator.

MATERIALS AND METHODS

Investigations were carried out in 2011 at the Medical University of Lublin in Poland, and Katolieke Hogeschool of Kortrijk in Belgium, after obtaining approval of the ethical committee of Polish Midwives Association (III/EC/2011/PMA). The project involved a total of 155 midwifery students, made up of 95 from Poland, and 60 from Belgium. Relations between opposing characteristics were tested with Chi-square (x2) test for independent traits. To assess the dependence relation between the examined variables Pearson's corrected coefficient was used. Data base and statistics were carried out with computer software STATISTICA 9.0 (StatSoftPoland).

CONCLUSIONS

Student knowledge on prevention against breast cancer was unsatisfactory.The students place of residence determined their self-estimation of personal knowledge of breast cancer prevention and diagnosing methods to assess the incidence of the disease, this knowledge being better with the students of Lublin. Better self-estimation in the students of Lublin of their personal knowledge on factors rising the risk of breast cancer, such as alimentation method, application of oral contraceptives and breast feeding was found than in Belgian students.

Socioeconomic inequalities in mortality in 16 European cities

AIMS

To explore inequalities in total mortality between small areas of 16 European cities for men and women, as well as to analyse the relationship between these geographical inequalities and their socioeconomic indicators.

METHODS

A cross-sectional ecological design was used to analyse small areas in 16 European cities (26,229,104 inhabitants). Most cities had mortality data for a period between 2000 and 2008 and population size data for the same period. Socioeconomic indicators included an index of socioeconomic deprivation, unemployment, and educational level. We estimated standardised mortality ratios and controlled for their variability using Bayesian models. We estimated relative risk of mortality and excess number of deaths according to socioeconomic indicators.

RESULTS

We observed a consistent pattern of inequality in mortality in almost all cities, with mortality increasing in parallel with socioeconomic deprivation. Socioeconomic inequalities in mortality were more pronounced for men than women, and relative inequalities were greater in Eastern and Northern European cities, and lower in some Western (men) and Southern (women) European cities. The pattern of excess number of deaths was slightly different, with greater inequality in some Western and Northern European cities and also in Budapest, and lower among women in Madrid and Barcelona.

CONCLUSIONS

In this study, we report a consistent pattern of socioeconomic inequalities in mortality in 16 European cities. Future studies should further explore specific causes of death, in order to determine whether the general pattern observed is consistent for each cause of death.

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.

Diverging trends in educational inequalities in cancer mortality between men and women in the 2000s in France

BACKGROUND

Socioeconomic inequalities in cancer mortality have been observed in different European countries and the US until the end of the 1990s, with changes over time in the magnitude of these inequalities and contrasted situations between countries. The aim of this study is to estimate relative and absolute educational differences in cancer mortality in France between 1999 and 2007, and to compare these inequalities with those reported during the 1990s.

METHODS

Data from a representative sample including 1% of the French population were analysed. Educational differences among people aged 30-74 were quantified with hazard ratios and relative indices of inequality (RII) computed using Cox regression models as well as mortality rate difference and population attributable fraction.

RESULTS

In the period 1999-2007, large relative inequalities were found among men for total cancer and smoking and/or alcohol related cancers mortality (lung, head and neck, oesophagus). Among women, educational differences were reported for total cancer, head and neck and uterus cancer mortality. No association was found between education and breast cancer mortality. Slight educational differences in colorectal cancer mortality were observed in men and women. For most frequent cancers, no change was observed in the magnitude of relative inequalities in mortality between the 1990s and the 2000s, although the RII for lung cancer increased both in men and women. Among women, a large increase in absolute inequalities in mortality was observed for all cancers combined, lung, head and neck and colorectal cancer. In contrast, among men, absolute inequalities in mortality decreased for all smoking and/or alcohol related cancers.

CONCLUSION

Although social inequalities in cancer mortality are still high among men, an encouraging trend is observed. Among women though, the situation regarding social inequalities is less favourable, mainly due to a health improvement limited to higher educated women. These inequalities may be expected to further increase in future years.

Do reproductive factors influence T, N, and M classes of ductal and lobular breast cancers? A nation-wide follow-up study

BACKGROUNDS

The clinical tumor-node-metastasis (T, N and M) classes of breast cancers provide important prognostic information. However, the possible association of TNM classes with reproductive factors has remained largely unexplored. Because every woman has a reproductive history, implications to outcome prediction are potentially significant.

METHODS

During the study period from 2002 through 2008, 5,614 pre- and 27,310 postmenopausal patients were identified in the Swedish Family-Cancer Database. Ordinal logistic regression analysis was used to estimate odds ratios (ORs) for TNM classes of breast cancers by histology. The reproductive variables were parity, age at first and last childbirth and time interval between first and last childbirth.

RESULTS

Among postmenopausal patients, the ORs for high-T class (T2-T4) (tumor size ≥2 cm) and metastasis were decreased by parity. A late age at first and last childbirth associated with high-T class and the effects were higher for lobular (OR for late age at first childbirth  = 2.85) than ductal carcinoma. Overall, long time interval between first and last childbirth was related to high-T class and metastasis. However, a short time interval between first and last childbirth in patients with late age at first or last childbirth increased the risk of metastasis. Late age at last childbirth was associated with increased occurrence of lobular carcinoma in situ. Among premenopausal ductal carcinoma patients, nulliparity and early age at first childbirth were associated with high-T class.

CONCLUSIONS

Increasing parity was protective against high-T class and metastasis; late ages at first and last childbirth were risk factors for high-T class in postmenopausal breast cancers. The current decline in parity and delayed age at first childbirth in many countries may negatively influence prognosis of breast cancer.

Time trends in breast cancer incidence and mortality in a mid-sized northeastern Brazilian city

Background

Breast cancer incidence within an area is usually proportional to the area’s income level. High-income areas have shown the highest incidence rates and since 2003, negative trends. As for mortality, rates are often higher in low-income regions. The purpose of this study was to analyze trends in incidence and mortality in a capital city of a northeastern Brazilian state with an intermediate human development index.

Methods

Incidence data from the Population-Based Cancer Registry of Aracaju and mortality data from the Official State Database for the period 1996–2006 were used. Incidence and mortality crude and age-standardized rates were calculated. Time trends were obtained using the Joinpoint Regression Model.

Results

For the period studied, invasive breast cancer age-standardized incidence rates increased annually with an annual percentage change (APC) of 2.9 (95% CI: 1.2-4.6). Significant increasing trends were observed in groups aged 45–54 years (APC: 3.9, 95% CI: 1.4 to 6.6), and 55–64 years (APC: 5.6, 95% CI: 1.8 to 9.6). Age-standardized mortality rates did not show an increasing trend (APC: 3.0, (95% CI: -2.8 to9.1), except for the group aged 55–64 years (APC: 11.3, 95% CI: 1.1 to 22.4).

Conclusions

In the study community, breast cancer showed increasing incidence among women in the peri- and postmenopausal periods. However, mortality did not present increasing overall trends, except for among the group aged 55–64 years. For better outcomes, screening policies should focus on the peri- and postmenopausal periods of women’s lives to diagnose disease.

Women's reflections and actions regarding working after breast cancer surgery - a focus group study

BACKGROUND

To better understand processes affecting return to work (RTW) after breast cancer, more knowledge from the perspective of sickness absentees is warranted. Still, research based on women's own reasoning and actions in RTW is very scarce. This study aims to elucidate how women with breast cancer reflect and act on work-related issues.

MATERIAL AND METHODS

Thematic analyses of data from four focus group interviews with 23 women who had had breast cancer surgery in the previous 3-13 months were carried out.

RESULTS

The five following themes of reflections regarding RTW were identified: 'health and functioning', 'self-esteem/integrity', 'value of work', 'relationships at work', and 'social circumstances'. These reflections were associated with the three identified themes of actions taken by the women: 'to work or to be sickness absent', 'to adjust work according to own needs or not', and 'to disclose or to hide one's cancer'. There was a distinct difference between women who experienced work as a source of well-being and those who needed a respite from work.

CONCLUSION

This study adds knowledge to the process of RTW after breast cancer and focuses on factors that lead the women to an active role in this process. We point to the interplay between women's own preferences, perceived competence, outer opportunities, and the actions each woman take with regard to RTW, which need to be recognized by all stakeholders involved. Furthermore, it continues to be essential to address the specific issue of disclosure in the workplace because this may be distressing for women.

Social inequalities and mortality in Europe--results from a large multi-national cohort

BACKGROUND

Socio-economic inequalities in mortality are observed at the country level in both North America and Europe. The purpose of this work is to investigate the contribution of specific risk factors to social inequalities in cause-specific mortality using a large multi-country cohort of Europeans.

METHODS

A total of 3,456,689 person/years follow-up of the European Prospective Investigation into Cancer and Nutrition (EPIC) was analysed. Educational level of subjects coming from 9 European countries was recorded as proxy for socio-economic status (SES). Cox proportional hazard model's with a step-wise inclusion of explanatory variables were used to explore the association between SES and mortality; a Relative Index of Inequality (RII) was calculated as measure of relative inequality.

RESULTS

Total mortality among men with the highest education level is reduced by 43% compared to men with the lowest (HR 0.57, 95% C.I. 0.52-0.61); among women by 29% (HR 0.71, 95% C.I. 0.64-0.78). The risk reduction was attenuated by 7% in men and 3% in women by the introduction of smoking and to a lesser extent (2% in men and 3% in women) by introducing body mass index and additional explanatory variables (alcohol consumption, leisure physical activity, fruit and vegetable intake) (3% in men and 5% in women). Social inequalities were highly statistically significant for all causes of death examined in men. In women, social inequalities were less strong, but statistically significant for all causes of death except for cancer-related mortality and injuries.

DISCUSSION

In this European study, substantial social inequalities in mortality among European men and women which cannot be fully explained away by accounting for known common risk factors for chronic diseases are reported.

Breast cancer risk by occupation and industry: analysis of the CECILE study, a population-based case-control study in France

BACKGROUND

It has been suggested that certain occupational exposures may play a role in breast cancer etiology. The recognition of high-risk occupations may give clues about potential mammary carcinogens in the work place.

METHODS

We conducted a population-based case-control study in France including 1,230 breast cancer cases and 1,315 population controls with detailed information on lifetime work history. Odds ratios for women ever employed in an occupation or industry were adjusted for well-established risk factors for breast cancer.

RESULTS

Adjusted odds ratios were marginally increased in some white-collar occupations, as well as in textile workers (2.4; 95% CI [0.9-6.0]), rubber and plastics product makers (1.8; 95% CI [0.9-3.5]), and in women employed for more than 10 years as nurses (1.4; 95% CI [0.9-2.1]) and as tailors/dressmakers (1.5; 95% CI [0.9-2.6]). The incidence of breast cancer was increased among women employed in the manufacture of chemicals, of non-metallic mineral products, and decreased among women in agriculture.

CONCLUSIONS

These findings suggest a possible role of occupational exposures in breast cancer, including night-shift work, solvents and endocrine disrupting chemicals and require further studies with detailed assessment of occupational exposures.