Environmental exposures, breast development and cancer risk: Through the looking glass of breast cancer prevention

Chemical contaminant exposures assessed using silicone wristbands among fuel station attendants, taxi drivers and commercial motorcycle riders in Kampala, Uganda

There are concerns over traffic-related air pollution in Uganda's capital, Kampala. Individuals in the transportation sector are hypothesized to be at greater risk for exposure to volatile organic compounds, given their proximity to vehicle exhaust. Silicone wristbands are a wearable technology that passively sample individuals' chemical exposures. We conducted a pilot cross sectional study to measure personal exposures to volatile organic compounds among 14 transportation workers who wore a wristband for five days. We analyzed for 75 volatile organic compounds; 33 chemicals (35%) were detected and quantified in at least 50% of the samples and 15 (16%) chemicals were detected and quantified across all the samples. Specific chemicals were associated with participants' occupation. The findings can guide future large studies to inform policy and practice to reduce exposure to chemicals in the environment in Kampala.

Exposure to p-dichlorobenzene and prevalent endocrine-related reproductive cancers among US women

P-dichlorobenzene (p-DCB) is a pest repellent and air deodorant that is commonly found in the household and public buildings. Exposure to p-DCB has been suggested to have potential metabolic and endocrine effects. Little is known about its association with endocrine-related female cancers. In this cross-sectional study, a nationally representative subsample of 4459 women, aged 20 years or older, in the 2003-2016 National Health and Nutrition Examination Survey was analyzed for the association between p-DCB exposure, measured as urinary concentrations of 2,5-dichlorophenol (2,5-DCP), the primary metabolite of p-DCB, and prevalent endocrine-related female cancers (defined as breast, ovarian, and uterine cancers) using multivariate logistic regression models, adjusting for potential confounders. Of the study participants, 202 women (weighted prevalence, 4.20%) reported being diagnosed with any of these endocrine-related reproductive cancers. Women with reproductive cancers showed a statistically significant increase in urinary 2,5-DCP concentrations (weighted geometric mean, 7.97 vs. 5.84 µg/g creatinine; p < 0.0001), compared to women without these cancers. After adjusting for potential confounders, we found that women in the moderate (1.94- < 28.10 µg/g creatinine) and high level (≥ 28.10 µg/g creatinine) of 2,5-DCP had significantly increased odds of endocrine-related reproductive cancers (odds ratio of 1.66 (95% CI: 1.02, 2.71) and 1.89 (1.08, 3.29), respectively), as compared with those in the low exposure group (< 1.94 µg/g creatinine). This study demonstrates a potential relation between p-DCB exposure and prevalent endocrine-related reproductive cancers in US women. Prospective and mechanistic studies would further explore these interactions and elucidate the pathogenesis of endocrine-related female cancers potentially associated with p-DCB exposure.

Best practices to quantify the impact of reproductive toxicants on development, function, and diseases of the rodent mammary gland

Work from numerous fields of study suggests that exposures to hormonally active chemicals during sensitive windows of development can alter mammary gland development, function, and disease risk. Stronger links between many environmental pollutants and disruptions to breast health continue to be documented in human populations, and there remain concerns that the methods utilized to identify, characterize, and prioritize these chemicals for risk assessment and risk management purposes are insufficient. There are also concerns that effects on the mammary gland have been largely ignored by regulatory agencies. Here, we provide technical guidance that is intended to enhance collection and evaluation of the mammary gland in mice and rats. We review several features of studies that should be controlled to properly evaluate the mammary gland, and then describe methods to appropriately collect the mammary gland from rodents. Furthermore, we discuss methods for preparing whole mounted mammary glands and numerous approaches that are available for the analysis of these samples. Finally, we conclude with several examples where analysis of the mammary gland revealed effects of environmental toxicants at low doses. Our work argues that the rodent mammary gland should be considered in chemical safety, hazard and risk assessments. It also suggests that improved measures of mammary gland outcomes, such as those we present in this review, should be included in the standardized methods evaluated by regulatory agencies such as the test guidelines used for identifying reproductive and developmental toxicants.

Evaluating the Feasibility of Continuing Medical Education for Disseminating Emerging Science on the Breast Cancer and Environment Connection

Developing continuing medical education (CME) training programs is a strategy for communicating emerging science to health practitioners. This research tests the feasibility of using CME modules for translating and disseminating research findings from the Breast Cancer and Environment Research Program. Recent findings have identified certain windows of susceptibility, like during puberty, in which exposure to endocrine-disrupting chemicals can increase breast cancer risk later in life. In order to reach pediatric patients and their caregivers, using a Diffusion of Innovations framework, pediatric health-care providers were identified as opinion leaders. Two CME modules informed by theory and formative research were tested with a sample of pediatricians and pediatric nurse practitioners. Participants completed knowledge, attitude, intention, and behavior items immediately before and after exposure to a randomly assigned module, and then again 3 weeks later. Quantitative and qualitative results indicate knowledge gain and strong links between practitioners' intentions to enact and implemented behavior learned from training recommendations with parents and caregivers in their practices. Results indicate that CMEs can be an effective strategy for translational activities targeted to health providers in order to change behavior within practice.

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.

Folate Deficiency Inhibits Development of the Mammary Gland and its Associated Lymphatics in FVB Mice

BACKGROUND

Folate is essential for DNA synthesis, DNA repair, cell proliferation, development, and morphogenesis. Folic acid (FA) is a nutritional supplement used to fortify human diets.

OBJECTIVES

We investigated the effects of dietary FA on early mammary gland (MG) development and hyperplasia.

METHODS

Study 1: nulliparous female FVB wild-type (WT) mice were fed control (Con; 2 mg FA/kg), deficient (Def; 0 mg FA/kg), excess (Ex; 5 mg FA/kg), or super excess (S-Ex; 20 mg FA/kg) diets for 8 wk before mating to WT or heterozygous FVB/N-Tg[mouse mammary tumor virus long terminal repeat (MMTV)-polyomavirus middle T antigen (PyVT)]634Mul/J (MMTV-PyMT+/-) transgenic males. Dams were fed these diets until they weaned WT or MMTV-PyMT+/- pups, which were fed the dam's diet from postnatal day (PND) 21 to 42. Tissues were collected from female progeny at PNDs 1, 21, and 42. Study 2: Con or Def diets were fed to WT intact females and males from PND 21 to 56, or to ovariectomized females from PND 21 to 77; tissues were collected at PND 56 or 77. Growth of all offspring, development of MGs, MG hyperplasia, supramammary lymph nodes, thymus and spleen, cell proliferation, and expression of MG growth factors were measured.

RESULTS

Study 1: Ex or S-Ex did not affect postnatal MG development or hyperplasia. The rate of isometric MG growth (PND 1-21) was reduced by 69% in Def female progeny (P < 0.0001). Similarly, hyperplastic growth in MGs of Def MMTV-PyMT+/- offspring was 18% of Con (P < 0.05). The Def diet reduced supramammary lymph node size by 20% (P < 0.0001) and increased MG insulin-like growth factor 2 mRNA by 200% (P < 0.05) and protein by 130%-150% (P < 0.05). Study 2: the Def diet did not affect MG growth, but it did reduce supramammary lymph node size (P < 0.05), spleen weight (P < 0.001), and thymic medulla area (P < 0.05).

CONCLUSIONS

In utero and postnatal folate deficiency reduced the isometric development of the MGs and early MG hyperplasia. Postnatal folate deficiency reduced the development of lymphatic tissues.

Rationale, Study Design, and Cohort Characteristics for the Markers for Environmental Exposures (MEE) Study

Environmental factors have been linked to many diseases and health conditions, but reliable assessment of environmental exposures is challenging. Developing biomarkers of environmental exposures, rather than relying on self-report, will improve our ability to assess the association of such exposures with disease. Epigenetic markers, most notably DNA methylation, have been identified for some environmental exposures, but identification of markers for additional exposures is still needed. The rationale behind the Markers for Environmental Exposures (MEE) Study was to (1) identify biomarkers, especially epigenetic markers, of environmental exposures, such as pesticides, air/food/water contaminants, and industrial chemicals that are commonly encountered in the general population; and (2) support the study of potential relationships between environmental exposures and health and health-related factors. The MEE Study is a cross-sectional study with potential for record linkage and follow-up. The well-characterized cohort of 400 postmenopausal women has generated a repository of biospecimens, including blood, urine, and saliva samples. Paired data include an environmental exposures questionnaire, a breast health questionnaire, dietary recalls, and a food frequency questionnaire. This work describes the rationale, study design, and cohort characteristics of the MEE Study. In addition to our primary research goals, we hope that the data and biorepository generated by this study will serve as a resource for future studies and collaboration.

DDT exposure during pregnancy and DNA methylation alterations in female offspring in the Child Health and Development Study

Studies measuring dichlorodiphenyltrichloroethane (DDT) exposure during key windows of susceptibility including the intrauterine period suggest that DDT exposure is associated with breast cancer risk. We hypothesized that prenatal DDT exposure is associated with DNA methylation. Using prospective data from 316 daughters in the Child Health and Development Study, we examined the association between prenatal exposure to DDTs and DNA methylation in blood collected in midlife (mean age: 49 years). To identify differentially methylated regions (DMRs) associated with markers of DDTs (p,p'-DDT and the primary metabolite of p,p'-DDT, p,p'-DDE, and o,p'-DDT, the primary constituents of technical DDT), we measured methylation in 30 genes important to breast cancer. We observed DDT DMRs in three genes, CCDC85A, CYP1A1 and ZFPM2, each of which has been previously implicated in pubertal development and breast cancer susceptibility. These findings suggest prenatal DDT exposure may have life-long consequence through alteration in genes relevant to breast cancer.

A meta-analysis of zinc levels in breast cancer

BACKGROUND

Breast cancer is the most commonly occurring neoplasm in females, comprising 16% of all female cancers worldwide. Various studies indicate some discrepancies regarding zinc (Zn) levels in various samples of breast cancer patients.

OBJECTIVE

The present study evaluated by meta-analysed the published data for Zn levels analyzed in breast tissue, plasma, serum, and hair samples and its relationship with breast cancer.

METHODS

The present meta-analysis included 36 studies, all of which were published in the years between 1984 to 2017 and selected by searching the databases MEDLINE, EMBASE, Cochrane Library, PubMed, Scopus, and the ISI Web of Knowledge. The articles were analyzed, and I² statistics were used to examine heterogeneity. The objective analysis was performed on data from the 36 studies, with total 1699 study subjects and 2009 controls.

RESULTS

Significant statistical differences overall were observed, based on a random effects model (SMD (95 % CI), -0.78[-1.40, -0.16], P = 0.014). Data from 19 of these studies indicated significant statistical differences between cancerous patients and controls with regard to serum and plasma Zn concentration (SMD [(95 %CI): -1.61(-2.43, -0.79)]. There was a significant statistical difference between the breast tissue and hair as regards Zn status (SMD (95%CI): 2.32(1.42, 3.21)) and (SMD (95v%CI): -1.80(-3.41, -0.20), respectively. Zn concentration levels typically decreased in blood and hair samples of patients with breast cancer, whereas it was elevated in tumor tissues.

CONCLUSIONS

There is a significant relationship between lowered serum Zn concentrations and risk of breast cancer onset or recurrences in women, but because of high heterogeneity, we recommend other primary studies.

Invasive breast cancer among Alaska Native women in Alaska

Female breast cancer is the most common cancer diagnosed among Alaska Native (AN) women. We examined characteristics of and trends for female breast cancer among AN women. We assessed descriptive statistics, incidence trends (1969-2014), and cause-specific survival for female breast cancers recorded in the Alaska Native Tumor Registry. Results indicated that the majority of breast cancers among AN were diagnosed among women aged over 50 years, at local stage, and with Hormone receptor (HR)+/Human Epidermal Growth Factor (HER) 2- subtype. Five-year average incidence (95% CI) in the most recent time-period (2009-2014) was 145.0/100,000 (130.4, 159.5)); this was not statistically different from the previous time-period. Survival from breast cancer was high and varied by stage and cancer subtype. Hazard of death was greater among those diagnosed with regional/distant/unknown disease, relative to local disease (HR (95%CI): 4.65 (1.66, 12.98)), and higher among those with HER2-/HR- cancers, relative to those with HER2-/HR+ cancers (HR (95%CI): 6.59 (2.23, 19.49)). This study provides a comprehensive description of breast cancer among AN women, providing new and updated information on clinical and demographic factors, cancer incidence trends, regional variations and breast cancer survival. Abbreviations: AIAN: American Indian/Alaska Native; AN: Alaska Native; ANMC: Alaska Native Medical Center; ANTR: Alaska Native Tumor Registry; CI: Confidence Interval; HR: Hazard Ratio; ICD-O-3: International Classification of Diseases for Oncology - Third Edition; NHW - Non-Hispanic Whites; SEER: Surveillance, Epidemiology and End Results.

Effects of Flaxseed and Its Components on Mammary Gland MiRNome: Identification of Potential Biomarkers to Prevent Breast Cancer Development

Breast cancer is the most common cancer among women worldwide. We previously showed that early-life exposure to flaxseed (FS) or its components, FS oil (FSO) and secoisolariciresinol diglucoside (SDG), affects the mammary gland (MG) and is associated with the reduction of breast cancer risk during adulthood. However, the underlying mechanisms are not understood. This study aimed to investigate the effect of FS, FSO, and SDG on the MG miRNA signature at a late stage of development. Female C57BL/6 mice, 4–5 weeks of age, were randomized into four groups to receive: (i) basal AIN-93G, (ii) 10% FS, (iii) 3.67% FSO, or (iv) 0.15% SDG. After 21 days, the mice were sacrificed and MG miRNAs were profiled. Diet-specific MG miRNA signatures were identified. Deregulated miRNAs were associated with breast cancer and targeted genes involved in MG development, growth, and cancer. The study allowed for the identification of potential biomarkers or novel therapeutic targets to prevent and/or reduce the risk of breast cancer.

Challenging dominant breast cancer research agendas: perspectives on the outcomes of the interagency breast cancer and environment research coordinating committee

BACKGROUND

As breast cancer rates increase globally, there is growing scientific consensus that greater understanding of the causes of breast cancer is needed to better prevent its occurrence. Genetics accounts for a small percentage of cases, thus environmental factors and epigenetics are increasingly suspect in breast cancer etiology. Within the breast cancer and environmental breast cancer social movements, there are longstanding calls for research and policy aimed toward the prevention of breast cancer. To better understand the opportunities and barriers to addressing environmental contributors to breast cancer, this article investigates both outcomes and perceptions of stakeholders involved in the Interagency Breast Cancer and Environment Research Coordinating Committee (IBCERCC). The IBCERCC was mandated by the 2008 U.S. Breast Cancer and Environmental Research Act, a law representing years of advocate and researcher efforts to produce national strategies and federal funding for breast cancer prevention research.

METHODS

To understand the meaning and impact of the IBCERCC advisory committee and final report, Prioritizing Prevention, I draw on fifteen confidential semi-structured interviews with members of the twenty-five person IBCERCC, in addition to six confidential semi-structured interviews with key breast cancer funders, advocates, and researchers affiliated with national reports on environmental contributors to cancer. I examine media coverage, congressional hearing transcripts, and official responses to the release of the IBCERCC report by governmental and non-governmental organizations.

RESULTS

Interviews and publicly available documents reveal a set of direct and indirect outcomes of the 2013 IBCERCC report. Interviewees in government positions perceived the 2014 renewal of the Breast Cancer and the Environment Research Program to result from IBCERCC efforts, notable in the context of declining U.S. federal research funding. Interviews also revealed a suite of potential barriers to the implementation of report recommendations including: distinct interpretations of the federal mandate, disparate assessments of scientific evidence, government funding crises, and lack of specificity around responsibility for implementation of report findings.

CONCLUSION

This article examines efforts to shift institutional research and funding priorities in cancer research towards prevention. Social science research can support efforts to shift institutional priorities by identifying broader social contexts and underlying values typically unnamed in scientific discourse.

Occupational exposure to endocrine disrupting substances and the risk of breast Cancer: the Singapore Chinese health study

Background

Evidence from basic research links exposure to endocrine disrupting chemicals (EDCs) with a higher risk for breast cancer. However, there is less evidence from observational epidemiological research and the results are equivocal. Therefore, we examined the association between occupational exposure to substances where exposure to EDCs is likely and the risk of breast cancer.

Methods

A prospective study consisting of a population-based cohort of 33,458 Singaporean Chinese women aged 45–74 years enrolled in the Singapore Chinese Health Study (SCHS) from 1993 to 98 and followed through 2014. Subjects’ self-reported occupational exposure and duration to industries, job titles, and substance types were garnered at baseline, and cases of incident breast cancer (N = 988) were determined by linkage with the Singapore Cancer Registry. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated for exposure to substances, job titles, and industries.

Results

There was no association between cumulative exposure to substances via occupation where EDC exposure is likely and risk of breast cancer. These results were consistent for hypothesized high (HR 0.94, 95% CI: 0.66–1.35), medium (HR 1.03 95% CI: 0.77–1.38) and low (HR 0.74, 95% CI 0.48–1.13) combined substance exposure groups when compared with those who were not exposed via occupation. Similar null associations were observed when examining job titles and industry categories.

Conclusions

There was no association between EDC related occupational exposures and breast cancer risk in working women of the Singaporean Chinese Health Study. Future studies that employ rigorous methods with regard to exposure assessment of EDCs are needed.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5862-2) contains supplementary material, which is available to authorized users.

Comparison of methods to assess onset of breast development in the LEGACY Girls Study: methodological considerations for studies of breast cancer

Background

Younger age at onset of breast development, which has been declining in recent decades, is associated with increased breast cancer risk independent of age at menarche. Given the need to study the drivers of these trends, it is essential to validate methods to assess breast onset that can be used in large-scale studies when direct clinical assessment of breast onset is not feasible.

Methods

Breast development is usually measured by Tanner stages (TSs), assessed either by physical examination or by mother’s report using a picture-based Sexual Maturation Scale (SMS). As an alternative, a mother-reported Pubertal Development Scale (PDS) without pictures has been used in some studies. We compared agreement of SMS and PDS with each other (n = 1022) and the accuracy of PDS with clinical TS as a gold standard for the subset of girls with this measure (n = 282) using the LEGACY cohort. We further compared prediction of breast onset using ROC curves and tested whether adding urinary estrone 1-glucuronide (E1G) improved the AUC.

Results

The agreement of PDS with SMS was high (kappa = 0.80). The sensitivity of PDS vs clinical TS was 86.6%. The AUCs for PDS alone and SMS alone were 0.88 and 0.79, respectively. Including E1G concentrations improved the AUC for both methods (0.91 and 0.86 for PDS and SMS, respectively).

Conclusions

The PDS without pictures is a highly accurate, sensitive, and specific method for assessing breast onset, especially in settings where clinical TS is not feasible. In addition, it is comparable to SMS methods with pictures and thus easier to implement in large-scale studies, particularly phone-based interviews where pictures may not be available. Urinary E1G can improve accuracy over than PDS or SMS alone.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0943-9) contains supplementary material, which is available to authorized users.

BCScreen: A gene panel to test for breast carcinogenesis in chemical safety screening

Targeted gene lists have been used in clinical settings to specify breast tumor type, and to predict breast cancer prognosis and response to treatment. Separately, panels have been curated to predict systemic toxicity and xenoestrogen activity as a part of chemical screening strategies. However, currently available panels do not specifically target biological processes relevant to breast development and carcinogenesis. We have developed a gene panel called the Breast Carcinogen Screen (BCScreen) as a tool to identify potential breast carcinogens and characterize mechanisms of toxicity. First, we used four seminal reviews to identify 14 key characteristics of breast carcinogenesis, such as apoptosis, immunomodulation, and genotoxicity. Then, using a hybrid data and knowledge-driven framework, we systematically combined information from whole transcriptome data from genomic databases, biomedical literature, the CTD chemical-gene interaction database, and primary literature review to generate a panel of 500 genes relevant to breast carcinogenesis. We used normalized pointwise mutual information (NPMI) to rank genes that frequently co-occurred with key characteristics in biomedical literature. We found that many genes identified for BCScreen were not included in prognostic breast cancer or systemic toxicity panels. For example, more than half of BCScreen genes were not included in the Tox21 S1500+ general toxicity gene list. Of the 230 that did overlap between the two panels, representation varied across characteristics of carcinogenesis ranging from 21% for genes associated with epigenetics to 82% for genes associated with xenobiotic metabolism. Enrichment analysis of BCScreen identified pathways and processes including response to steroid hormones, cancer, cell cycle, apoptosis, DNA damage and breast cancer. The biologically-based systematic approach to gene prioritization demonstrated here provides a flexible framework for creating disease-focused gene panels to support discovery related to etiology. With validation, BCScreen may also be useful for toxicological screening relevant to breast carcinogenesis.

Disparities in breast cancer survival in the United States (2001-2009): Findings from the CONCORD-2 study

BACKGROUND

Reducing breast cancer incidence and achieving equity in breast cancer outcomes remains a priority for public health practitioners, health care providers, policy makers, and health advocates. Monitoring breast cancer survival can help evaluate the effectiveness of health services, quantify inequities in outcomes between states or population subgroups, and inform efforts to improve the effectiveness of cancer management and treatment.

METHODS

We analyzed breast cancer survival using individual patient records from 37 statewide registries that participated in the CONCORD-2 study, covering approximately 80% of the US population. Females were diagnosed between 2001 and 2009 and were followed through December 31, 2009. Age-standardized net survival at 1 year, 3 years, and 5 years after diagnosis was estimated by state, race (white, black), stage at diagnosis, and calendar period (2001-2003 and 2004-2009).

RESULTS

Overall, 5-year breast cancer net survival was very high (88.2%). Survival remained remarkably high from 2001 through 2009. Between 2001 and 2003, survival was 89.1% for white females and 76.9% for black females. Between 2004 and 2009, survival was 89.6% for white females and 78.4% for black females.

CONCLUSIONS

Breast cancer survival was more than 10 percentage points lower for black females than for white females, and this difference persisted over time. Reducing racial disparities in survival remains a challenge that requires broad, coordinated efforts at the federal, state, and local levels. Monitoring trends in breast cancer survival can highlight populations in need of improved cancer management and treatment. Cancer 2017;123:5100-18. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Estimation of Breast Cancer Incident Cases and Medical Care Costs Attributable to Alcohol Consumption Among Insured Women Aged <45 Years in the U.S

INTRODUCTION

This study estimated the percentage of breast cancer cases, total number of incident cases, and total annual medical care costs attributable to alcohol consumption among insured younger women (aged 18-44 years) by type of insurance and stage at diagnosis.

METHODS

The study used the 2012-2013 National Survey on Drug Use and Health, cancer incidence data from two national registry programs, and published relative risk measures to estimate the: (1) alcohol-attributable fraction of breast cancer cases among younger women by insurance type; (2) total number of breast cancer incident cases attributable to alcohol consumption by stage at diagnosis and insurance type among younger women; and (3) total annual medical care costs of treating breast cancer incident cases attributable to alcohol consumption among younger women. Analyses were conducted in 2016; costs were expressed in 2014 U.S. dollars.

RESULTS

Among younger women enrolled in Medicaid, private insurance, and both groups, 8.7% (95% CI=7.4%, 10.0%), 13.8% (95% CI=13.3%, 14.4%), and 12.3% (95% CI=11.4%, 13.1%) of all breast cancer cases, respectively, were attributable to alcohol consumption. Localized stage was the largest proportion of estimated attributable incident cases. The estimated total number of breast cancer incident alcohol-attributable cases was 1,636 (95% CI=1,570, 1,703) and accounted for estimated total annual medical care costs of $148.4 million (95% CI=$140.6 million, $156.1 million).

CONCLUSIONS

Alcohol-attributable breast cancer has estimated medical care costs of nearly $150 million per year. The current findings could be used to support evidence-based interventions to reduce alcohol consumption in younger women.

Prevalence of Modifiable Cancer Risk Factors Among U.S. Adults Aged 18-44 Years

INTRODUCTION

Carcinogen exposure and unhealthy habits acquired in young adulthood can set the stage for the development of cancer at older ages. This study measured the current prevalence of several cancer risk factors among young adults to assess opportunities to intervene to change the prevalence of these risk factors and potentially reduce cancer incidence.

METHODS

Using 2015 National Health Interview Survey data (analyzed in 2016), the prevalence of potential cancer risk factors was estimated among U.S. adults aged 18-44 years, based on responses to questions about diet, physical activity, tobacco product use, alcohol, indoor tanning, sleep, human papillomavirus vaccine receipt, and obesity, stratified by sex, age, and race/ethnicity.

RESULTS

The prevalence of some risk factors varied by age and race/ethnicity. Obesity (one in four people) and insufficient sleep (one in three people) were common among men and women. Physical inactivity (one in five men, one in four women); binge drinking (one in four men, one in eight women); cigarette smoking (one in five men, one in seven women); and frequent consumption of red meat (one in four men, one in six women) also were common. More than half of the population of adults aged 18-44 years consumed sugar-sweetened beverages daily and processed meat at least once a week. Most young adults had never had the human papillomavirus vaccine.

CONCLUSIONS

Findings can be used to target evidence-based environmental and policy interventions to reduce the prevalence of cancer risk factors among young adults and prevent the development of future cancers.

Maternal Anthropometry and Mammographic Density in Adult Daughters

OBJECTIVE

We examined the relation between maternal anthropometry and mammographic density in the adult daughter using prospectively collected data.

METHODS

Our study included a total of 700 mother-daughter dyads participating in an adult follow-up of women born in 2 US birth cohorts: the Child Health and Development Study and the Boston, Massachusetts, and Providence, Rhode Island sites of the National Collaborative Perinatal Project.

RESULTS

We observed an increased percent breast density at a mean age of 43.1 years in the daughters of mothers who gained 5 kg or less during pregnancy compared with mother-daughter pairs in which the mother gained 5 to 10 kg (β = 4.8, 95% confidence interval: 1.0 to 8.6). The daughters of mothers who were overweight at the time of conception (prepregnancy BMI ≥25) and who gained >5 kg during pregnancy had a lower percent density (β = -3.2, 95% confidence interval: -6.2 to -0.2) compared with mothers with a BMI <25 at conception who gained >5 kg.

CONCLUSIONS

We did not find any strong and consistent patterns between maternal anthropometry and the daughter's breast density, a strong predictor of breast cancer risk. A modest association between low gestational weight gain and increased breast density 40 years later in the daughter was observed, even after accounting for adult body size, and if confirmed, possible mechanisms need to be further elucidated.

Environmental and Economic Strategies for Primary Prevention of Cancer in Early Life

This article summarizes the evidence for environmental toxic exposures contributing to cancers in early life, focusing on the most common cancer sites in this age group. It provides examples of widespread avoidable exposures to human carcinogens through air, water, and food and then describes recent examples of successful initiatives to reduce exposure to chemicals linked to these cancer sites, through government policy, industry initiatives, and consumer activism. State government initiatives to reduce toxic chemical exposures have made important gains; the Toxics Use Reduction Act of Massachusetts is now 25 years old and has been a major success story. There are a growing number of corporate initiatives to eliminate toxics, especially carcinogens, from the products they manufacture and sell. Another important opportunity for cancer prevention is provided by online databases that list chemicals, their toxicity, and lower-toxicity alternatives; these can be used by businesses, health care institutions, consumers, and workers to reduce exposures to chemicals of concern. The article concludes by inviting pediatricians and public health professionals to include elimination of carcinogen exposures in their work to promote primary prevention of cancer in early life.

Opportunities During Early Life for Cancer Prevention: Highlights From a Series of Virtual Meetings With Experts

Compelling evidence suggests that early life exposures can affect lifetime cancer risk. In 2014, the Centers for Disease Control and Prevention's (CDC's) Cancer Prevention Across the Lifespan Workgroup hosted a series of virtual meetings with select experts to discuss the state of the evidence linking factors during the prenatal period and early childhood to subsequent risk of both pediatric and adult cancers. In this article, we present the results from a qualitative analysis of the meeting transcripts and summarize themes that emerged from our discussions with meeting participants. Themes included the state of the evidence linking early life factors to cancer risk, research gaps and challenges, the level of evidence needed to support taking public health action, and the challenges of communicating complex, and sometimes conflicting, scientific findings to the public. Opportunities for collaboration among public health agencies and other stakeholders were identified during these discussions. Potential next steps for the CDC and its partners included advancing and building upon epidemiology and surveillance work, developing and using evidence from multiple sources to inform decision-making, disseminating and communicating research findings in a clear and effective way, and expanding collaborations with grantees and other partners. As the science on early life factors and cancer risk continues to evolve, there are opportunities for collaboration to translate science into actionable public health practice.

Differences in the Rate of in Situ Mammary Gland Development and Other Developmental Endpoints in Three Strains of Female Rat Commonly Used in Mammary Carcinogenesis Studies: Implications for Timing of Carcinogen Exposure

The potential of chemicals to alter susceptibility to mammary tumor formation is often assessed using a carcinogen-induced study design in various rat strains. The rate of mammary gland (MG) development must be considered so that the timing of carcinogen administration is impactful. In this study, in situ MG development was assessed in females of the Harlan Sprague-Dawley (Hsd:SD), Charles River Sprague-Dawley (Crl:SD), and Charles River Long-Evans (Crl:LE) rat strains at postnatal days 25, 33, and 45. Development was evaluated by physical assessment of growth parameters, developmental scoring, and quantitative morphometric analysis. Although body weight (BW) was consistently lower and day of vaginal opening (VO) occurred latest in female Hsd:SD rats, they exhibited accelerated pre- and peripubertal MG development compared to other strains. Glands of Crl:SD and Crl:LE rats exhibited significantly more terminal end buds (TEBs) and TEB/mm than Hsd:SD rats around the time of VO. These data suggest a considerable difference in the rate of MG development across commonly used strains, which is independent of BW and timing of VO. In mammary tumor induction studies employing these strains, administration of the carcinogen should be timed appropriately, based on strain, to specifically target the peak of TEB occurrence.

Sentinel California sea lions provide insight into legacy organochlorine exposure trends and their association with cancer and infectious disease

BACKGROUND

Organochlorine contaminants (OCs), like polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethanes (DDTs), are widespread marine pollutants resulting from massive historical use and environmental persistence. Exposure to and health effects of these OCs in the marine environment may be examined by studying California sea lions (Zalophus californianus), which are long lived, apex predators capable of accumulating OCs.

METHODS

We evaluated PCB and DDT levels in 310 sea lions sampled between 1992 and 2007: 204 individuals stranded along the coast of central California, 60 healthy males from Washington State, and 46 healthy females from southern California. Lipid-normalized contaminant concentrations were analyzed using general linear models and logistic regression to ascertain temporal trends; differences between stranded and healthy sea lions; and association of organochlorines with sex, age, and presence of cancer or fatal infectious disease.

RESULTS

Concentrations of the contaminants in stranded adults decreased over time in the study period (adjusted for sex, as adult males had higher mean blubber concentrations than adult females and juveniles). Cancer was almost eight and six times more likely in animals with higher summed PCBs and DDTs, compared to those with lower levels (95% CI 5.55-10.51 and 4.54-7.99, respectively). Fatal infectious diseases were similarly seven and five times more likely in animals with higher contaminant burdens (95% CI 4.20-10.89 and 3.27-7.86, respectively). Mean contaminant loads were significantly higher in stranded sea lions than in healthy live captured animals (p < 0.001).

CONCLUSION

Organochlorine contamination has significant associations with health outcomes in California sea lions, raising concerns for humans and other animals eating tainted seafood. While environmental exposure to these organochlorines appears to be decreasing over time based on levels in sea lion tissues, their persistence in the environment and food web for all predators, including humans, and the associated serious health risks, warrant monitoring, possibly through sentinel species like marine mammals.