Timing of Environmental Exposures as a Critical Element in Breast Cancer Risk

EGFR and Hippo signaling pathways are involved in organophosphate esters-induced proliferation and migration of triple-negative breast cancer cells

The widespread application of organophosphate flame retardants has led to pervasive exposure to organophosphate esters (OPEs), prompting considerable concerns regarding their potential health risk to humans. Despite hints from previous research about OPEs' association with breast cancer, their specific effects and underlying mechanisms of triple-negative breast cancer (TNBC) remain unclear. In this study, we investigated the effects of four representative OPEs on cell proliferation, cell cycle regulation, migration, and the expression of genes and proteins associated with the epidermal growth factor receptor (EGFR) and Hippo signaling pathways in TNBC (MDA-MB-231) cells. Our findings revealed that treatment with 1-25 μM triphenyl phosphate (TPHP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) induced TNBC cell proliferation and accelerated cell cycle progression, with upregulation in MYC, CCND1, and BRCA1 mRNA. Moreover, exposure to 1-25 μM TPHP, 10-25 μM TDCIPP, and 1-10 μM tris (2-chloroethyl) phosphate (TCEP) induced MMP2/9 mRNA expression and enhanced migratory capacity, except for 2-ethylhexyl diphenyl phosphate (EHDPP). Mechanistically, four OPEs treatments activated the EGFR-ERK1/2 and EGFR-PI3K/AKT signaling pathways by increasing the transcript of EGFR, ERK1/2, PI3K, and AKT mRNA. OPEs treatment also suppressed the Hippo signaling pathway by inhibiting the expression of MST1 mRNA and phosphorylation of LATS1, leading to the overactivation of YAP1 protein, thereby promoting TNBC cell proliferation and migration. In summary, our study elucidated that activation of the EGFR signaling pathway and suppression of the Hippo signaling pathway contributed to the proliferation, cell cycle dysregulation, and migration of TNBC cells following exposure to OPEs.

Postpartum Breast Cancer and Survival in Women With Germline BRCA Pathogenic Variants

Importance

In young-onset breast cancer (YOBC), a diagnosis within 5 to 10 years of childbirth is associated with increased mortality. Women with germline BRCA1/2 pathogenic variants (PVs) are more likely to be diagnosed with BC at younger ages, but the impact of childbirth on mortality is unknown.

Objective

To determine whether time between most recent childbirth and BC diagnosis is associated with mortality among patients with YOBC and germline BRCA1/2 PVs.

Design, Setting, and Participants

This prospective cohort study included women with germline BRCA1/2 PVs diagnosed with stage I to III BC at age 45 years or younger between 1950 and 2021 in the United Kingdom, who were followed up until November 2021. Data were analyzed from December 3, 2021, to November 29, 2023.

Exposure

Time between most recent childbirth and subsequent BC diagnosis, with recent childbirth defined as 0 to less than 10 years, further delineated to 0 to less than 5 years and 5 to less than 10 years.

Main Outcomes and Measures

The primary outcome was all-cause mortality, censored at 20 years after YOBC diagnosis. Mortality of nulliparous women was compared with the recent post partum groups and the 10 or more years post partum group. Cox proportional hazards regression analyses were adjusted for age, tumor stage, and further stratified by tumor estrogen receptor (ER) and BRCA gene status.

Results

Among 903 women with BRCA PVs (mean [SD] age at diagnosis, 34.7 [6.1] years; mean [SD] follow-up, 10.8 [9.8] years), 419 received a BC diagnosis 0 to less than 10 years after childbirth, including 228 women diagnosed less than 5 years after childbirth and 191 women diagnosed 5 to less than 10 years after childbirth. Increased all-cause mortality was observed in women diagnosed within 5 to less than 10 years post partum (hazard ratio [HR], 1.56 [95% CI, 1.05-2.30]) compared with nulliparous women and women diagnosed 10 or more years after childbirth, suggesting a transient duration of postpartum risk. Risk of mortality was greater for women with ER-positive BC in the less than 5 years post partum group (HR, 2.35 [95% CI, 1.02-5.42]) and ER-negative BC in the 5 to less than 10 years post partum group (HR, 3.12 [95% CI, 1.22-7.97]) compared with the nulliparous group. Delineated by BRCA1 or BRCA2, mortality in the 5 to less than 10 years post partum group was significantly increased, but only for BRCA1 carriers (HR, 2.03 [95% CI, 1.15-3.58]).

Conclusions and Relevance

These findings suggest that YOBC with germline BRCA PVs was associated with increased risk for all-cause mortality if diagnosed within 10 years after last childbirth, with risk highest for ER-positive BC diagnosed less than 5 years post partum, and for ER-negative BC diagnosed 5 to less than 10 years post partum. BRCA1 carriers were at highest risk for poor prognosis when diagnosed at 5 to less than 10 years post partum. No such associations were observed for BRCA2 carriers. These results should inform genetic counseling, prevention, and treatment strategies for BRCA PV carriers.

The effects of environmental aryl hydrocarbon receptor ligands on signaling and cell metabolism in cancer

Dioxin and dioxin-like compounds are chlorinated organic pollutants formed during the manufacturing of other chemicals. Dioxins are ligands of the aryl hydrocarbon receptor (AHR), that induce AHR-mediated biochemical and toxic responses and are persistent in the environment. 2,3,7,8- tetrachlorodibenzo para dioxin (TCDD) is the prototypical AHR ligand and its effects represent dioxins. TCDD induces toxicity, immunosuppression and is a suspected tumor promoter. The role of TCDD in cancer however is debated and context-dependent. Environmental particulate matter, polycyclic aromatic hydrocarbons, perfluorooctane sulfonamide, endogenous AHR ligands, and cAMP signaling activate AHR through TCDD-independent pathways. The effect of activated AHR in cancer is context-dependent. The ability of FDA-approved drugs to modulate AHR activity has sparked interest in their repurposing for cancer therapy. TCDD by interfering with endogenous pathways, and overstimulating other endogenous pathways influences all stages of cancer. Herein we review signaling mechanisms that activate AHR and mechanisms by which activated AHR modulates signaling in cancer including affected metabolic pathways.

New insights into the effect of bisphenol AF exposure on maternal mammary glands at various stages of gestation in mice

Bisphenol AF (BPAF) is the most estrogenic compound among BPA analogs. Mammary glands (MDs) are special organs that undergo repeated cycles of structural development, metabolism, and functional differentiation. Gestation is a sensitive window for MDs. In the present study, plug-positive CD-1 mice were exposed to vehicle (Veh) or 300 μg/kg BPAF through oral gavage every second day during gestation, and maternal MDs were collected from different developmental windows at 9.5, 13.5, and 18.5 d of gestation (gestation day [GD]9.5, GD13.5 and GD18.5). The results showed that gestational BPAF exposure induced a significantly elevated MD density at GD18.5. Non-target metabolomics analysis was used to screen for tyrosine, valine, ornithine, proline, threonine, phenylalanine and asymmetrical dimethylarginine (ADMA) amino acids, which changed significantly at all time points. Furthermore, the mRNA expression levels of genes related to these amino acids also changed significantly. Additionally, amino acid levels in BPAF-treated MGs at GD18.5 were related to the serum ammonia concentration of the corresponding offspring. These results provide a comprehensive view of the adverse effects of BPAF exposure during gestation on the maternal MG structure and function, which may affect milk components during lactation. Moreover, higher amino acids content may lead to amino acid imbalance or hyperammonemia in newborns.

Health-related toxicity of emerging per- and polyfluoroalkyl substances: Comparison to legacy PFOS and PFOA

Per- and polyfluoroalkyl substances (PFAS) are highly persistent, manufactured chemicals used in various manufacturing processes and found in numerous commercial products. With over 9000 compounds belonging to this chemical class, there is increasing concern regarding human exposure to these compounds due to their persistent, bioaccumulative, and toxic nature. Human exposure to PFAS may occur from a variety of exposure sources, including, air, food, indoor dust, soil, water, from the transfer of PFAS from non-stick wrappers to food, use of cosmetics, and other personal care products. This critical review presents recent research on the health-related impacts of PFAS exposure, highlighting compounds other than Perfluorooctanoic acid (PFOA) and Perfluoroctane sulfonate (PFOS) that cause adverse health effects, updates the current state of knowledge on PFAS toxicity, and, where possible, elucidates cause-and-effect relationships. Recent reviews identified that exposure to PFAS was associated with adverse health impacts on female and male fertility, metabolism in pregnancy, endocrine function including pancreatic dysfunction and risk of developing Type 2 diabetes, lipid metabolism and risk of childhood adiposity, hepatic and renal function, immune function, cardiovascular health (atherosclerosis), bone health including risk for dental cavities, osteoporosis, and vitamin D deficiency, neurological function, and risk of developing breast cancer. However, while cause-and-effect relationships for many of these outcomes were not able to be clearly elucidated, it was identified that 1) the evidence derived from both animal models and humans suggested that PFAS may exert harmful impacts on both animals and humans, however extrapolating data from animal to human studies was complicated due to differences in exposure/elimination kinetics, 2) PFAS precursor kinetics and toxicity mechanism data are still limited despite ongoing exposures, and 3) studies in humans, which provide contrasting results require further investigation of the long-term-exposed population to better evaluate the biological toxicity of chronic exposure to PFAS.

Home mortgage discrimination and incidence of triple-negative and Luminal A breast cancer among non-Hispanic Black and non-Hispanic White females in California, 2006-2015

Purpose

In the United States, Black females are burdened by more aggressive subtypes and increased mortality from breast cancer compared to non-Hispanic (NH) White females. Institutional racism may contribute to these inequities. We aimed to characterize the association between home mortgage discrimination, a novel measure of institutional racism, and incidence of Luminal A and triple-negative breast cancer (TNBC) subtypes among NH Black and NH White females in California metropolitan areas.

Methods

We merged data from the California Cancer Registry on females aged 20 + diagnosed with primary invasive breast cancer between 2006 and 2015 with a census tract-level index of home mortgage lending bias measuring the odds of mortgage loan denial for Black versus White applicants, generated from the 2007–2013 Home Mortgage Disclosure Act database. Poisson regression estimated cross-sectional associations of census tract-level racial bias in mortgage lending with race/ethnicity- and Luminal A and TNBC-specific incidence rate ratios, adjusting for neighborhood confounders.

Results

We identified n = 102,853 cases of Luminal A and n = 15,528 cases of TNBC over the study period. Compared to NH Whites, NH Black females had higher rates of TNBC, lower rates of Luminal A breast cancer, and lived in census tracts with less racial bias in home mortgage lending. There was no evidence of association between neighborhood racial bias in mortgage lending at the time of diagnosis and either subtype among either racial/ethnic group.

Conclusion

Future research should incorporate residential history data with measures of institutional racism to improve estimation and inform policy interventions.

In utero exposure to 17α-hydroxyprogesterone caproate and risk of cancer in offspring

BACKGROUND

17α-hydroxyprogesterone caproate is a synthetic progestogen initially approved in the 1950s to treat gynecologic and obstetrical conditions. Despite continued concerns about safety and short-term efficacy regarding the use of 17α-hydroxyprogesterone caproate for the prevention of preterm birth in pregnant women, little is known about the long-term effects of 17α-hydroxyprogesterone caproate on the health of the offsprings.

OBJECTIVE

To examine the association between in utero exposure to 17α-hydroxyprogesterone caproate and the risk of cancer in the offspring.

STUDY DESIGN

The Child Health and Development Studies was a population-based cohort of >18,000 mother-child dyads receiving prenatal care in the Kaiser Foundation Health Plan (Oakland, CA) between 1959 and 1966. Clinical information was abstracted from the mothers' medical records beginning 6 months before pregnancy through delivery. We identified the number and timing of 17α-hydroxyprogesterone caproate injections during pregnancy. Incident cancers diagnosed in the offspring were ascertained through 2019 by linkage to the California Cancer Registry. We used the Cox proportional hazard models to estimate the adjusted hazard ratios and their 95% confidence intervals, with the follow-up time accrued from the date of birth through the date of cancer diagnosis, death, or last contact.

RESULTS

A total of 1008 offspring were diagnosed with cancer over 730,817 person-years of follow-up. Approximately 1.0% of the offspring (n=234) were exposed in utero to 17α-hydroxyprogesterone caproate. Exposure in the first trimester was associated with an increased risk of any cancer (adjusted hazard ratio, 2.57; 95% confidence interval, 1.59-4.15), and the risk increased with the number of injections (1-2 injections: adjusted hazard ratio, 1.80; 95% confidence interval, 1.12-2.90; ≥3 injections: adjusted hazard ratio, 3.07; 95% confidence interval, 1.34-7.05). Exposure in the second or third trimester conferred an additional risk for the male (adjusted hazard ratio, 2.59; 95% confidence interval, 1.07-6.28) but not for the female (adjusted hazard ratio, 0.30; 95% confidence interval, 0.04-1.11) offspring. The risk of colorectal (adjusted hazard ratio, 5.51; 95% confidence interval, 1.73-17.59), prostate (adjusted hazard ratio, 5.10; 95% confidence interval, 1.24-21.00), and pediatric brain (adjusted hazard ratio, 34.72; 95% confidence interval, 7.29-164.33) cancer was higher in the offspring first exposed to 17α-hydroxyprogesterone caproate in the first trimester than the offspring not exposed.

CONCLUSION

Caution using 17α-hydroxyprogesterone caproate in early pregnancy is warranted, given the possible link with cancer in the offspring.

Breast cancer risk in relation to ambient concentrations of nitrogen dioxide and particulate matter: results of a population-based case-control study corrected for potential selection bias (the CECILE study)

BACKGROUND

There is only scant evidence that air pollution increases the risk of breast cancer.

OBJECTIVES

We investigated this relationship for three air pollutants: nitrogen dioxide (NO₂) and particulate matter with an aerodynamical diameter below 10 µm (PM₁₀) and 2.5 µm (PM_2.5).

METHODS

We conducted a population-based case-control study on breast cancer in two French départements, including 1,229 women diagnosed with breast cancer in 2005-2007 and 1,316 control women frequency-matched on age. Concentrations of NO₂, PM₁₀ and PM_2.5 at participants' addresses occupied during the last 10 years were assessed using a chemistry transport model. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using multivariable logistic regression models where each woman was assigned a weight depending on her probability of selection into the study.

RESULTS

The OR for breast cancer per 10-µg/m³ increase in NO₂ was 1.11 (95% CI, 0.98, 1.26), and 1.41 (95% CI 1.07, 1.86) in the highest exposure quintile (Q5), compared to the first. The ORs per 10-µg/m³ NO₂ did not markedly differ between pre- (OR 1.09, 95% CI 0.89, 1.35)) and post-menopausal women (OR 1.14, 95% CI 0.97, 1.33)), but the OR was substantially higher for hormone-receptor positive (ER+/PR+) breast tumor subtypes (OR 1.15, 95% CI 1.00, 1.31) than for ER-/PR- tumors (OR 0.95, 95% CI 0.72, 1.26). Breast cancer risk was not associated with either PM₁₀ (OR per 1 µg/m³ 1.01, 95% CI, 0.96, 1.06) or PM_2.5 (OR per 1 µg/m³ 1.02, 95% CI 0.95, 1.08), regardless of the menopausal status or of the breast tumor subtype.

DISCUSSION

Our study provides evidence that NO₂ exposure, a marker of traffic-related air pollutants, may be associated with an increased risk of breast cancer, particularly ER+/PR+ tumors.

Molecular mechanisms of mammary gland remodeling: A review of the homeostatic versus bisphenol a disrupted microenvironment

Mammary gland (MG) undergoes critical points of structural changes throughout a woman's life. During the perinatal and pubertal stages, MG develops through growth and differentiation to establish a pre-mature feature. If pregnancy and lactation occur, the epithelial compartment branches and differentiates to create a specialized structure for milk secretion and nurturing of the newborn. However, the ultimate MG modification consists of a regression process aiming to reestablish the smaller and less energy demanding structure until another production cycle happens. The unraveling of these fascinating physiologic cycles has helped the scientific community elucidate aspects of molecular regulation of proliferative and apoptotic events and remodeling of the stromal compartment. However, greater understanding of the hormonal pathways involved in MG developmental stages led to concern that endocrine disruptors such as bisphenol A (BPA), may influence these specific development/involution stages, called "windows of susceptibility". Since it is used in the manufacture of polycarbonate plastics and epoxy resins, BPA is a ubiquitous chemical present in human everyday life, exerting an estrogenic effect. Thus, descriptions of its deleterious effects on the MG, especially in terms of serum hormone concentrations, hormonal receptor expression, molecular pathways, and epigenetic alterations, have been widely published. Therefore, allied to a didactic description of the main physiological mechanisms involved in different critical points of MG development, the current review provides a summary of key mechanisms by which the endocrine disruptor BPA impacts MG homeostasis at different windows of susceptibility, causing short- and long-term effects.

Differential susceptibility to endocrine disruptor-induced epimutagenesis

There is now considerable evidence indicating the potential for endocrine disrupting chemicals to alter the epigenome and for subsets of these epigenomic changes or "epimutations" to be heritably transmitted to offspring in subsequent generations. While there have been many studies indicating how exposure to endocrine disrupting chemicals can disrupt various organs associated with the body's endocrine systems, there is relatively limited information regarding the relative susceptibility of different specific organs, tissues, or cell types to endocrine disrupting chemical-induced epimutagenesis. Here we review available information about different organs, tissues, cell types, and/or cell lines which have been shown to be susceptible to specific endocrine disrupting chemical-induced epimutations. In addition, we discuss possible mechanisms that may be involved, or impacted by this tissue- or cell type-specific, differential susceptibility to different endocrine disrupting chemicals. Finally, we summarize available information indicating that certain periods of development display elevated susceptibility to endocrine disrupting chemical exposure and we describe how this may affect the extent to which germline epimutations can be transmitted inter- or transgenerationally. We conclude that cell type-specific differential susceptibility to endocrine disrupting chemical-induced epimutagenesis is likely to directly impact the extent to, or manner in, which endocrine disrupting chemical exposure initially induces epigenetic changes to DNA methylation and/or histone modifications, and how these endocrine disrupting chemical-induced epimutations can then subsequently impact gene expression, potentially leading to the development of heritable disease states.

Diet and Transgenerational Epigenetic Inheritance of Breast Cancer: The Role of the Paternal Germline

The past decade has made evident that in addition to passing their genetic material at conception, parents also transmit a molecular memory of past environmental experiences, including nutritional status, to their progeny through epigenetic mechanisms. In the 1990s, it was proposed that breast cancer originates in utero. Since then, an overwhelming number of studies in human cohorts and animal models have provided support for that hypothesis. It is becoming clear, however, that exposure in the parent generation can lead to multigenerational and transgenerational inheritance of breast cancer. Importantly, recent data from our lab and others show that pre-conception paternal diets reprogram the male germline and modulate breast cancer development in offspring. This review explores the emerging evidence for transgenerational epigenetic inheritance of breast cancer focusing on studies associated with ancestral nutritional factors or related markers such as birth weight. We also explore paternal factors and the epigenetic mechanisms of inheritance through the male germline while also reviewing the existing literature on maternal exposures in pregnancy and its effects on subsequent generations. Finally, we discuss the importance of this mode of inheritance in the context of breast cancer prevention, the challenges, and outstanding research questions in the field.

DDT and Breast Cancer: Prospective Study of Induction Time and Susceptibility Windows

BACKGROUND

In a previous Child Health and Development Studies report, p, p'-DDT was associated with a fivefold increased risk of premenopausal (before age 50 years) breast cancer for women first exposed before puberty. Here we extend our observation to breast cancer diagnosed during early postmenopause (ages 50-54 years) to determine whether age at diagnosis modifies the interaction of DDT with age at exposure.

METHODS

We conducted a second prospective, nested case-control study in the Child Health and Development Studies (153 incident breast cancer cases diagnosed at ages 50-54 years and 432 controls matched to cases on birth year). These were analyzed separately and pooled with our previous study (129 breast cancer cases diagnosed at ages 31-49 years and 129 controls matched on birth year). Blood samples were obtained during pregnancy (median age, 26 years), 1-3 days after delivery from 1959 to 1967 in Oakland, California. Serum was assayed for p, p'-DDT, o, p'-DDT, and p, p'-DDE. Odds ratios (ORs) below are given for doubling of serum p, p'-DDT. All statistical tests were two-sided.

RESULTS

For early postmenopausal breast cancer, p, p'-DDT was associated with risk for all women (ORDDT 50-54 = 1.99, 95% CI = 1.48 to 2.67). This association was accounted for by women first exposed to DDT after infancy (ORDDT 50-54 for first exposure after infancy = 2.83, 95% CI = 1.96 to 4.10 vs ORDDT 50-54 for first exposure during infancy = 0.56, 95% CI = 0.26 to 1.19; Pinteraction DDT x age at first exposure = .01). In contrast, for premenopausal breast cancer, p, p'-DDT was associated with risk among women first exposed during infancy through puberty, but not after (ORDDT<50 for first exposure during infancy = 3.70, 95% CI = 1.22 to 11.26, Pinteraction DDT x age at first exposure x age at diagnosis = .03).

CONCLUSIONS

p, p'-DDT was associated with breast cancer through age 54 years. Risk depended on timing of first exposure and diagnosis age, suggesting susceptibility windows and an induction period beginning in early life. DDT appears to be an endocrine disruptor with responsive breast targets from in utero to menopause.

Genoprotective activities of plant natural substances in cancer and chemopreventive strategies in the context of 3P medicine

Severe durable changes may occur to the DNA structure caused by exogenous and endogenous risk factors initiating the process of carcinogenesis. By evidence, a large portion of malignancies have been demonstrated as being preventable. Moreover, the targeted prevention of cancer onset is possible, due to unique properties of plant bioactive compounds. Although genoprotective effects of phytochemicals have been well documented, there is an evident lack of articles which would systematically present the spectrum of anticancer effects by phytochemicals, plant extracts, and plant-derived diet applicable to stratified patient groups at the level of targeted primary (cancer development) and secondary (cancer progression and metastatic disease) prevention. Consequently, clinical implementation of knowledge accumulated in the area is still highly restricted. To stimulate coherent co-development of the dedicated plant bioactive compound investigation on one hand and comprehensive cancer preventive strategies on the other hand, the current paper highlights and deeply analyses relevant evidence available in the area. Key molecular mechanisms are presented to detail genoprotective and anticancer activities of plants and phytochemicals. Clinical implementation is discussed. Based on the presented evidence, advanced chemopreventive strategies in the context of 3P medicine are considered.

Herbicide, fumigant, and fungicide use and breast cancer risk among farmers' wives

Evidence from epidemiologic and laboratory studies relating pesticides to breast cancer risk is inconsistent. Women engaging in agricultural work or living in agricultural areas may experience appreciable exposures to a wide range of pesticides, including herbicides, fumigants, and fungicides.

METHODS

We examined exposure to herbicides, fumigants, and fungicides in relation to breast cancer risk among farmers' wives with no prior history of breast cancer in the Agricultural Health Study. Women provided information on pesticide use, demographics, and reproductive history at enrollment (1993-1997) and at a 5-year follow-up interview. We used Cox proportional hazards regression to estimate associations (hazard ratios [HRs] and 95% confidence intervals [CIs]) between the women's and their husbands' self-reported use of individual pesticides and incident breast cancer risk.

RESULTS

Out of 30,594 women, 38% reported using herbicides, fumigants, or fungicides and 1,081 were diagnosed with breast cancer during a median 15.3 years of follow-up. We found elevated risk in relation to women's ever use of the fungicide benomyl (HR = 1.6; 95% CI = 0.9, 2.7) and the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) (HR = 1.6; 95% CI = 0.8, 3.1) and to their husbands' use of the herbicide 2-(2,4,5-trichlorophenoxy) propionic acid (2,4,5-TP) (HR = 1.5; 95% CI = 0.9, 2.7). We observed few other chemical associations and little evidence of differential risk by tumor estrogen receptor status or linear exposure-response relationships.

CONCLUSION

We did not observe clear excesses between use of specific pesticides and breast cancer risk across exposure metrics, although we did observe elevated risk associated with women's use of benomyl and 2,4,5-T and husbands' use of 2,4,5-TP.

Barriers and opportunities for breast cancer organizations to focus on environmental health and disease prevention: a mixed-methods approach using website analyses, interviews, and focus groups

BACKGROUND

Breast cancer is the most commonly diagnosed cancer among women worldwide and most cases are not due to high risk inherited genes. In response, breast cancer activists successfully advocated for innovative research on environmental chemical exposures as a possible cause. Since then, new evidence supports hypotheses that common industrial and consumer chemicals are linked to the disease, and expert panels recommend reducing exposures. We evaluated whether these research results and recommendations are translated back into the work of breast cancer organizations and what barriers and opportunities influence their ability to focus on environmental factors.

METHODS

We used a Python script to evaluate the frequency of environmental terms on the websites of 81 breast cancer organizations (> 14,000 associated URLs) and conducted two focus groups and 20 interviews with leaders of breast cancer organizations. We also analyzed the frequency of terms on two trusted, national cancer websites.

RESULTS

40% of organizations include information on environmental chemicals on their websites, but references are infrequent and rarely cite specific chemicals of concern. Most organizations (82%) discuss other risk factors such as exercise, diet, family history, or genetics. From interviews and focus groups, we identified four types of barriers to addressing environmental chemicals: 1) time and resource constraints, 2) limited knowledge of the state of the research and lack of access to experts, 3) difficulties with messaging, including concern that cultural and economic factors make it difficult for individuals to reduce their exposures, and 4) institutional obstacles, such as the downplaying of environmental risks by industry interests. Participants expressed the desire for easy-to-adopt educational programs and increased federal funding for scientist-advocate research partnerships.

CONCLUSION

Our research underscores the need for environmental breast cancer experts and trusted cancer organizations to increase research translation activities so that breast cancer organizations can communicate new science on environmental factors in their online and in-person work. Moreover, our research highlights how most groups are focusing on providing resources to diagnosed women, including addressing problems with healthcare access, which displaces their ability to work on breast cancer prevention.

In utero DDT exposure and breast density before age 50

Prior studies in the Child Health and Development Studies (CHDS) found in utero exposure to the pesticide, dichlorodiphenyltrichloroethane (DDT), increased breast cancer risk by age 52. Mammographic density is considered a primary risk factor for breast cancer. We conducted a study of 309 daughters from the CHDS to examine in utero DDT exposure and mammographic density in midlife. Among daughters with high (>75th percentile) exposure to p,p'-Dichlorodiphenyldichloroethylene (DDE), p,p'-DDT was significantly correlated with increased dense area and percent density regardless of her body mass in midlife. In the subset of women with lower (<75th percentile) p,p-DDE, p,p'-DDT was associated with increased non-dense breast area. This was explained by adjustment for midlife BMI suggesting that p,p'-DDT may be obesogenic. In aggregate our findings indicate that early life p,p'-DDT exposure impacts breast density in a complex way that depends on the hosts biological ability to sequester and process DDT and levels of exposure.

In utero exposure to poly- and perfluoroalkyl substances (PFASs) and subsequent breast cancer

We tested the hypothesis that maternal perinatal serum levels of poly and perfluoroalkyl substances (PFASs) predict risk for breast cancer in daughters in a 54-year follow-up of 9300 daughters born 1959-1967 in the Child Health and Development Studies pregnancy cohort. Total cholesterol and PFASs were measured in archived maternal perinatal serum for 102 daughter breast cancer cases diagnosed by age 52, and 310 controls matched on birth year and blood draw trimester. High maternal N-ethyl-perfluorooctane sulfonamido acetic acid (EtFOSAA), a precursor of perfluorooctane sulfonic acid (PFOS), in combination with high maternal total cholesterol predicted a 3.6-fold increased risk of breast cancer (p_interaction<0.05). Conversely, maternal PFOS was associated with decreased daughters' breast cancer risk. Predictions were robust to alternative modeling and independent of other maternal factors. Future generations continue to be exposed to ubiquitous, persistent PFASs. These findings are relevant to breast cancer prevention if confirmed experimentally and where possible, in additional epidemiology studies of internal doses of PFASs and other chemical mixtures especially during vulnerable windows in early life.

Di(2-ethylhexyl) phthalate (DEHP) increases proliferation of epithelial breast cancer cells through progesterone receptor dysregulation

The di(2-ethylhexyl) phthalate (DEHP) is a plasticizer incorporated to plastic matrices of widely used consumer products. However, it is gradually released from these products, resulting in a chronic exposure for humans. Although DEHP, similar to other members of the phthalates family, is generally considered as an endocrine disruptor, the mechanisms implicated in its toxicity are yet poorly understood. Our objective was to determine the effects of an exposure to DEHP and to one of its major metabolite, the mono(2-ethylhexyl) phthalate (MEHP) on markers involved in breast carcinogenesis. T-47D cells were exposed to environmentally relevant and higher doses of DEHP and MEHP (0.1-10 000 nM) for 4 days. Our results showed that an exposure to 10 000 nM of DEHP and 0.1 nM of MEHP significantly increased the proliferation of T-47D cells, without inducing apoptosis. In addition, a significant increase in the protein levels of the isoform A of the progesterone receptor (PR) and of nuclear levels of PR were observed in T-47D cells exposed to 10 000 nM of DEHP. Importantly, the increased proliferation and nuclear levels of PR were totally and partially inhibited, respectively, by Mifepristone, a PR antagonist. These results suggest that an exposure to DEHP or MEHP increase cell proliferation by activating PR signaling, which could potentially increase the risks to develop breast cancer. The mechanism of activation of the progesterone pathway by DEHP and the long-term consequences of this activation remained to be elucidated.

Endocrine disruptors (EDs) and hormone-dependent cancers: Correlation or causal relationship?

The selective increase in the incidence of hormone-dependent cancers (breast, prostate, testicular) in industrialized countries is associated with the increasing number of endocrine disruptors (EDs) in the environment and raises questions about the role of EDs in mammary carcinogenesis. Answering these questions is difficult because the number of EDs is large and varies with time. Moreover hormonal carcinogenesis is multifactorial and progresses slowly and in stages. This discussion will be limited to breast cancer and three EDs: distilbene, bisphenol A (BPA), and dichlorodiphenyltrichloroethane (DDT). All these three EDs bind estrogen receptors, albeit with widely different affinities. Several complementary approaches have been used: French cancer records, epidemiological studies on cohorts followed over several decades, numerous in vitro experimental studies using cell cultures and in vivo animal studies. These approaches all converge to the same result, strongly suggesting a causal relationship between EDs and precancerous lesions. Except for distilbene, the mechanisms and molecular targets involved are still unclear, which makes it difficult to look for substitute products that are just as efficient, but less toxic.

NEAT1 negatively regulates miR-218 expression and promotes breast cancer progression

BACKGROUND

Studies have shown that lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) is related to breast cancer progression, however, the role of NEAT1 remains largely unknown. The aim of the current study was to further investigate the function of NEAT1 involved in breast cancer.

METHODS

QRT-PCR was used to analyze lncRNA NEAT1 expression in breast cancer tissues and determine the association between NEAT1 and clinicopathologic features in patients. Kaplan-Meier analysis and the log-rank test were used to establish the relationship between NEAT1 and overall survival. Cell proliferation and invasion were evaluated based on CCK8 cell proliferation, cell colony formation and Transwell cell invasion assays results. Bioinformatics analysis and the luciferase reporter assay were performed to demonstrate the association between NEAT1 and miR-218.

RESULTS

NEAT1 expression was significantly up-regulated in breast cancer tissues compared to adjacent normal tissues, and higher NEAT1 was positively associated with lymph node metastasis and TNM stage. Patients with higher NEAT1 had a poor prognosis. Furthermore, miR-218 was shown to be a direct target of NEAT1 in breast cancer cells. In addition, NEAT1 promoted cell invasion and proliferation by negatively regulating miR-218 in breast cancer.

CONCLUSION

NEAT1 is a potential biomarker for prognosis and the target of treatment in breast cancer patients.

Test-Retest Reproducibility of Adult-Reported High School Diet Varies among Racially and Ethnically Diverse US Men and Women

Background

Adolescent diet is thought to play an important role in future chronic disease risk. However, few studies have examined the reproducibility of adult-reported adolescent diet, and evidence for possible differences in reproducibility by demographic characteristics is limited.

Objective

We assessed the ability of adults to consistently report past high school diet over a 1-y period and examined differences in reproducibility by selected demographic characteristics.

Methods

By using age-adjusted partial Spearman (ρ) or Pearson (r) correlations, we assessed 1-y reproducibility for 33 line items, 20 food groups, and 2 dietary patterns of high school diet reported in adulthood via a questionnaire completed by 742 participants in the Cancer Prevention Study 3 (CPS-3) Diet Substudy.

Results

Participants' median age was 53 y (range: 31-70 y), 65.2% were women, 59.8% were non-Hispanic white, 24.8% were non-Hispanic black, and 15.4% were Hispanic. The mean Spearman correlation assessing reproducibility across the 33 line items was 0.60 and ranged from 0.44 to 0.72, with no differences in mean correlations by age, sex, race/ethnicity, education, or body mass index (BMI). Reproducibility was similar across food groups (ρ = 0.62; range: 0.44-0.68), with differences by sex, ethnicity, age, or BMI observed for some food groups (e.g., sugar-sweetened beverages). Pearson correlations for the reproducibility of 2 major eating patterns, "fast food" and "whole food," were 0.73 and 0.72, respectively.

Conclusion

These results show good 1-y reproducibility of assessed high school diet, as reported from memory in adulthood, by line item, food group, and dietary pattern, with noted differences by demographic characteristics.

Residential particulate matter and distance to roadways in relation to mammographic density: results from the Nurses' Health Studies

BACKGROUND

High mammographic density is a strong, well-established breast cancer risk factor. Three studies conducted in various smaller geographic settings reported inconsistent findings between air pollution and mammographic density. We assessed whether particulate matter (PM) exposures (PM2.5, PM2.5-10, and PM10) and distance to roadways were associated with mammographic density among women residing across the United States.

METHODS

The Nurses' Health Studies are prospective cohorts for whom a subset has screening mammograms from the 1990s (interquartile range 1990-1999). PM was estimated using spatio-temporal models linked to residential addresses. Among 3258 women (average age at mammogram 52.7 years), we performed multivariable linear regression to assess associations between square-root-transformed mammographic density and PM within 1 and 3 years before the mammogram. For linear regression estimates of PM in relation to untransformed mammographic density outcomes, bootstrapped robust standard errors are used to calculate 95% confidence intervals (CIs). Analyses were stratified by menopausal status and region of residence.

RESULTS

Recent PM and distance to roadways were not associated with mammographic density in premenopausal women (PM2.5 within 3 years before mammogram β = 0.05, 95% CI -0.16, 0.27; PM2.5-10 β = 0, 95%, CI -0.15, 0.16; PM10 β = 0.02, 95% CI -0.10, 0.13) and postmenopausal women (PM2.5 within 3 years before mammogram β = -0.05, 95% CI -0.27, 0.17; PM2.5-10 β = -0.01, 95% CI -0.16, 0.14; PM10 β = -0.02, 95% CI -0.13, 0.09). Largely null associations were observed within regions. Suggestive associations were observed among postmenopausal women in the Northeast (n = 745), where a 10-μg/m3 increase in PM2.5 within 3 years before the mammogram was associated with 3.4 percentage points higher percent mammographic density (95% CI -0.5, 7.3).

CONCLUSIONS

These findings do not support that recent PM or roadway exposures influence mammographic density. Although PM was largely not associated with mammographic density, we cannot rule out the role of PM during earlier exposure time windows and possible associations among northeastern postmenopausal women.

Insecticide Use and Breast Cancer Risk among Farmers' Wives in the Agricultural Health Study

BACKGROUND

Some epidemiologic and laboratory studies suggest that insecticides are related to increased breast cancer risk, but the evidence is inconsistent. Women engaged in agricultural work or who reside in agricultural areas may experience appreciable exposures to a wide range of insecticides.

OBJECTIVE

We examined associations between insecticide use and breast cancer incidence among wives of pesticide applicators (farmers) in the prospective Agricultural Health Study.

METHODS

Farmers and their wives provided information on insecticide use, demographics, and reproductive history at enrollment in 1993-1997 and in 5-y follow-up interviews. Cancer incidence was determined via cancer registries. Among 30,594 wives with no history of breast cancer before enrollment, we examined breast cancer risk in relation to the women's and their husbands' insecticide use using Cox proportional hazards regression to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

During an average 14.7-y follow-up, 39% of the women reported ever using insecticides, and 1,081 were diagnosed with breast cancer. Although ever use of insecticides overall was not associated with breast cancer risk, risk was elevated among women who had ever used the organophosphates chlorpyrifos [HR=1.4 (95% CI: 1.0, 2.0)] or terbufos [HR=1.5 (95% CI: 1.0, 2.1)], with nonsignificantly increased risks for coumaphos [HR=1.5 (95% CI: 0.9, 2.5)] and heptachlor [HR=1.5 (95% CI: 0.7, 2.9)]. Risk in relation to the wives' use was associated primarily with premenopausal breast cancer. We found little evidence of differential risk by tumor estrogen receptor status. Among women who did not apply pesticides, the husband's use of fonofos was associated with elevated risk, although no exposure-response trend was observed.

CONCLUSION

Use of several organophosphate insecticides was associated with elevated breast cancer risk. However, associations for the women's and husbands' use of these insecticides showed limited concordance. Ongoing cohort follow-up may help clarify the relationship, if any, between individual insecticide exposures and breast cancer risk. https://doi.org/10.1289/EHP1295.

State of the evidence 2017: an update on the connection between breast cancer and the environment

BACKGROUND

In this review, we examine the continually expanding and increasingly compelling data linking radiation and various chemicals in our environment to the current high incidence of breast cancer. Singly and in combination, these toxicants may have contributed significantly to the increasing rates of breast cancer observed over the past several decades. Exposures early in development from gestation through adolescence and early adulthood are particularly of concern as they re-shape the program of genetic, epigenetic and physiological processes in the developing mammary system, leading to an increased risk for developing breast cancer. In the 8 years since we last published a comprehensive review of the relevant literature, hundreds of new papers have appeared supporting this link, and in this update, the evidence on this topic is more extensive and of better quality than that previously available.

CONCLUSION

Increasing evidence from epidemiological studies, as well as a better understanding of mechanisms linking toxicants with development of breast cancer, all reinforce the conclusion that exposures to these substances - many of which are found in common, everyday products and byproducts - may lead to increased risk of developing breast cancer. Moving forward, attention to methodological limitations, especially in relevant epidemiological and animal models, will need to be addressed to allow clearer and more direct connections to be evaluated.

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.

Tumor Phenotype and Gene Expression During Early Mammary Tumor Development in Offspring Exposed to Alcohol In Utero

BACKGROUND

Alcohol exposure in utero increases susceptibility to carcinogen-induced mammary tumorigenesis in adult offspring and causes tumors with a more malignant phenotype. This study was conducted to identify changes early in tumor development that might lead to this outcome.

METHODS

Pregnant Sprague-Dawley rats were fed a liquid diet containing 6.7% ethanol (alcohol), an isocaloric liquid diet without alcohol (pair-fed), or rat chow ad libitum (ad lib) from gestation day 7 until parturition. At birth, female progeny were cross-fostered to control dams. Pups were weaned at postnatal day (PND) 21 and fed rat chow ad libitum for the remainder of the experiment. Female offspring were administered N-nitroso-N-methylurea (NMU; 50 mg/kg body weight) on PND 50. Mammary glands were palpated weekly, and offspring were euthanized at 16 weeks post-NMU injection.

RESULTS

At 16 weeks post-NMU, tumor multiplicity was greater in alcohol-exposed offspring compared with control groups. Estrogen receptor-α (ER) mRNA expression was decreased in tumors from alcohol-exposed offspring, and these animals developed more ER-negative tumors relative to the pair-fed group. Alcohol-exposed offspring also tended to develop more progesterone receptor (PR)-positive tumors. All tumors were HER2-negative. PR positivity was associated with higher Ki67 expression, suggesting that PR-positive tumors were more proliferative. Tumors from alcohol-exposed animals exhibited increased mRNA expression of the insulin-like growth factor (IGF) family members IGF-II and IGFBP-5. IGF-II and DNA methyltransferase mRNA tended to be greater in the normal contralateral mammary glands of these animals.

CONCLUSIONS

These data indicate that alcohol exposure in utero may shift NMU-induced tumor development toward a more aggressive phenotype and that alterations in IGF-II expression may contribute to these changes. Additional studies should be aimed at epigenetic mechanisms that underlie IGF-II expression to further delineate how this gene is altered in mammary glands of adults exposed to alcohol in utero.