Environmental risk factors for breast cancer among African-American women

Optimisation Models for Pathway Activity Inference in Cancer

BACKGROUND

With advances in high-throughput technologies, there has been an enormous increase in data related to profiling the activity of molecules in disease. While such data provide more comprehensive information on cellular actions, their large volume and complexity pose difficulty in accurate classification of disease phenotypes. Therefore, novel modelling methods that can improve accuracy while offering interpretable means of analysis are required. Biological pathways can be used to incorporate a priori knowledge of biological interactions to decrease data dimensionality and increase the biological interpretability of machine learning models.

METHODOLOGY

A mathematical optimisation model is proposed for pathway activity inference towards precise disease phenotype prediction and is applied to RNA-Seq datasets. The model is based on mixed-integer linear programming (MILP) mathematical optimisation principles and infers pathway activity as the linear combination of pathway member gene expression, multiplying expression values with model-determined gene weights that are optimised to maximise discrimination of phenotype classes and minimise incorrect sample allocation.

RESULTS

The model is evaluated on the transcriptome of breast and colorectal cancer, and exhibits solution results of good optimality as well as good prediction performance on related cancer subtypes. Two baseline pathway activity inference methods and three advanced methods are used for comparison. Sample prediction accuracy, robustness against noise expression data, and survival analysis suggest competitive prediction performance of our model while providing interpretability and insight on key pathways and genes. Overall, our work demonstrates that the flexible nature of mathematical programming lends itself well to developing efficient computational strategies for pathway activity inference and disease subtype prediction.

The 811 C/T polymorphism in the 3' untranslated region of the selenoprotein 15-kDa (Sep15) gene and breast cancer in Caucasian women

The 15-kDa selenoprotein (Sep15) is a selenocysteine-containing oxidoreductase in the endoplasmic reticulum that participates in disulfide-bond formation and protein folding control. The 3'-untranslated region (3'-UTR) contains two exclusively linked, polymorphic sites at positions 811 (C/T) and 1125 (G/A), which result in two functional haplotypes: 811C/1125G or 811T/1125A. The 811T/1125A variant occurs significantly more often in African-Americans as compared to Caucasians and has been linked to increased breast cancer risk in black women. We studied the 811C/T (rs5845) Sep15 gene polymorphism in 182 Caucasian women-83 breast cancer cases and 99 healthy controls-by pyrosequencing and polymerase chain reaction. Associations between allelic variants and clinico-pathological variables (e.g., age, stage of disease, tumor type, grading, and receptor status) were investigated. The genotype distribution in breast cancer patients (CC 63.9 %, CT 33.7 %, TT 2.4 %) and controls (69.7 %, CT 28.3 %, TT 2 %) showed no significant difference (OR 0.77, 95 % CI 0.41-1.42, p = 0.4). The overall low prevalence of the T allele was in accordance with that reported for Caucasians in previous studies. There was no significant association between 811C/T Sep15 polymorphism and any of clinico-pathological parameters. In conclusion, we are the first to report on 811C/T SEP 15 polymorphism in white breast cancer patients. Genotype variation within the 3'-UTR of the SEP 15 gene showed no association with breast cancer risk or clinico-pathological parameters in Caucasian women.

Ethnic disparities in breast cancer

Breast cancer is the leading cause of cancer death for women worldwide. While breast cancer incidence is lower for many ethnic minority women than for white women, stage at diagnosis and survival are often worse. These disparities are most marked for African-American women, but are also present for Asians, Latinas, Native Americans and Hawaiians. The etiology of ethnic disparities in breast cancer is multifactorial, including differences in tumor characteristics, genetics, access to care and insurance, prevalence of risk factors, screening participation and processes of care, such as timeliness of diagnosis and quality of communication and treatment. This review will examine what is known regarding ethnic differences in all of these areas, what questions remain, and where researchers and policy makers should focus their future efforts.

Epidemiology, determinants, and consequences of cigarette smoking in African American women: an integrative review

Tobacco smoking is a national public health problem that has been associated with numerous adverse health effects, including increased disease and cancer rates. Previous review articles on smoking in specific demographic populations have focused on smoking in women and on smoking in African Americans, but have not considered the dual roles of ethnicity and gender in smoking behavior. African American women (AAW) are an important subgroup to study because they are distinct from non-AAW and their male African American counterparts on biopsychosocial factors that are relevant to smoking behavior. The purpose of the present review paper is to integrate and summarize the current literature on the epidemiology, determinants, and consequences of cigarette smoking among AAW, by contrasting them to relevant comparison groups (non-AAW and African American men). Evidence suggests that AAW are generally more likely to be light smokers and initiate smoking later. The prevalence rates of AAW smokers have decreased over the past 25years, yet AAW are disproportionately affected by several smoking-related illnesses when compared to their ethnic and gender comparison groups. AAW smokers are distinct from relevant comparison groups in metabolic sensitivity to nicotine, aspects of smoking topography, and several psychosocial factors that influence smoking. Although a small literature on smoking in AAW is emerging, further empirical research of AAW smokers could inform the development of tailored interventions for AAW.

Public Health Implications of Household Pharmaceutical Waste in the United States

Household pharmaceuticals are ubiquitous and untold quantities are wasted annually. Most often, people dispose of household pharmaceuticals by flushing them down the toilet, pouring them down the drain, or throwing them away in the trash. Pharmaceuticals disposed in this manner compromise the safety of our environment. This article provides a comprehensive review on the public health issue of household pharmaceutical waste, describing its epidemiology, explaining its effects on aquatic and human life, estimating its cost burden, and discussing strategies for reducing environmental exposure to it. In doing so, this article proposes two key objectives for our nation: (1) reduce the amount of household pharmaceuticals wasted and (2) devise environmentally friendly and cost-effective ways for handling this waste once it has been generated.

Environmental contributions to disparities in pregnancy outcomes

One of the most persistent disparities in American health status is the pronounced difference in birth outcomes between non-Hispanic black and non-Hispanic white women. Poor pregnancy outcomes have a substantial impact on mortality, morbidity, and health care costs. Increasing evidence indicates that environmental exposures are associated with poor birth outcomes. This paper reviews the latest research on how environmental exposures affect pregnancy outcomes and then discusses how these exposures may be embedded within a context of significant social and host factor stress. The analysis suggests that environmental, social, and host factors are cumulatively stressing non-Hispanic black women and that this cumulative stress may be a cause of the persistent disparities in pregnancy outcomes.

Communicating Cancer Risk Reduction

This review discusses considerations in the development and dissemination of cancer risk reduction appeals and associated challenges to the amelioration of health-compromising behaviors. Strategic implications for empirically driven public policy initiatives and primary care also are addressed.

Apocrine sweat gland obstruction by antiperspirants allowing transdermal absorption of cutaneous generated hormones and pheromones as a link to the observed incidence rates of breast and prostate cancer in the 20th century

Breast and prostate cancer share similarities and likely represent homologous cancers in females and males, respectively. The role of hormones such as testosterone and estrogen in carcinogenesis is well established. Despite worldwide research efforts, the pathogenesis of these diseases is largely not well understood. Personal care products containing estrogens or xenoestrogens have raised concern as a breast cancer risk, especially in young African-American women. In the United States (US) there is a parallel rise in the incidence in breast and prostate cancer compared to selected non-hormone dependent tumors. Observed US and global breast and prostate cancer incidence increases were occurring before exogenous hormone replacement and xenoestrogen exposure were commonplace. An unintentional, inadvertent, and long term hormone exposure may occur from transdermal absorption of sex hormones and pheromones (androgens) from axillary apocrine sweat gland obstruction by aluminum-based antiperspirants. The global rise in antiperspirant use parallels rises in breast and prostate cancer incidence and mortality rates. A multi-disciplinary literature based set of evidence is presented on how such a link is possible, to prompt confirmatory investigations in the pursuit of unmet needs in breast and prostate cancer etiology and prevention.

Family history of cancer predicts Papanicolaou screening behavior for African American and white women

BACKGROUND

Understanding women's motivations for getting Papanicolaou (Pap) screening has the potential to impact cancer disparities. This study examined whether having a family history of cancer was a predictor for Pap screening.

METHODS

By using the National Health Interview Survey 2000 Cancer Control and Family modules, we identified a subsample (n=15,509) of African American (n=2774) and white women (n=12,735) unaffected by cancer, with and without a family history of cancer. Data were analyzed using logistic regression models.

RESULTS

African American and white women with a positive family history of cancer were 42% (P<.0001) more likely to have had a recent Papanicolaou (Pap) test than their counterparts without a family history of cancer. Among African American women, those with a positive family history of cancer were 53% more likely to have had a recent Pap test, whereas among white women those with a positive family history of cancer were 41% more likely to have received a Pap test. African American women with a family history of cancer were more likely to have had a recent Pap test than white women with or without a family history of cancer.

CONCLUSIONS

This study presents a unique perspective on Pap screening behavior. Having an immediate family member with any cancer statistically predicted having a recent Pap test for both African American and white women. Because these results demonstrated that regardless of the cancer type, having an immediate affected family member is a motivator for cervical cancer screening behavior, healthcare providers managing cancer treatment patients have a teachable opportunity that extends beyond the patient.

Risk factors for breast cancer in a black population--the Barbados National Cancer Study

The Barbados National Cancer Study (BNCS) is a nationwide case-control study investigating environmental and genetic factors for breast cancer (BC) in a predominantly African-origin population with similar ancestry as African-Americans. This report evaluates associations of incident BC in the BNCS to various factors, including demographic, anthropometric, reproductive and family history variables, not investigated previously in this population. The BNCS included 241 incident BC cases and 481 age-matched female controls, with mean ages of 57 and 56 years, respectively. In addition to a reported family history of BC in a close relative [odds ratios (OR) = 3.74, 95% CI (1.41, 9.90) in a parent; OR = 3.26 (1.47, 7.21) in a sibling], other factors associated with BC were older age at first full-term pregnancy [OR = 1.04 (1.00, 1.07)] and having a history of benign breast disease [OR = 1.88 (1.19, 2.99)]. Increased parity reduced the risk of BC [OR = 0.34 (0.15, 0.77) among those with >or=3 children]. The reproductive patterns of African-Barbadian (AB) women tended to differ from those of African-American (AA) women (later age of menarche, earlier age at first pregnancy, higher frequency of lactation and infrequent use of exogenous hormones) and could help to explain their considerably lower postmenopausal incidence of BC. The relationship between reported family history and BC, combined with the associations noted for several reproductive and other variables, supports the genetic and environmental contributions to BC, which may vary in populations across the African diaspora. Further investigations of other populations may clarify these issues.

Personal care products that contain estrogens or xenoestrogens may increase breast cancer risk

Established models of breast cancer risk, such as the Gail model, do not account for patterns of the disease in women under the age of 35, especially in African Americans. With the possible exceptions of ionizing radiation or inheriting a known genetic mutation, most of the known risk factors for breast cancer are related to cumulative lifetime exposure to estrogens. Increased risk of breast cancer has been associated with earlier onset of menses or later age at menopause, nulliparity or late first parity, use of hormonal contraceptives or hormone replacement therapy, shorter lactation history, exposure to light at night, obesity, and regular ingestion of alcohol, all of which increase circulating levels of unbound estradiol. Among African Americans at all ages, use of hormone-containing personal care products (PCPs) is more common than among whites, as is premature appearance of secondary sexual characteristics among infants and toddlers. We hypothesize that the use of estrogen and other hormone-containing PCPs in young African American women accounts, in part, for their increased risk of breast cancer prior to menopause, by subjecting breast buds to elevated estrogen exposure during critical windows of vulnerability in utero and in early life. These early life and continuing exposures to estrogenic and xenoestrogenic agents may also contribute to the increased lethality of breast cancer in young women in general and in African American women of all ages. Public disclosure by manufacturers of proprietary hormonally active ingredients is required for this research to move forward.

Environmental oestrogens, cosmetics and breast cancer

The established role of oestrogen in the development and progression of breast cancer raises questions concerning a potential contribution from the many chemicals in the environment which can enter the human breast and which have oestrogenic activity. A range of organochlorine pesticides and polychlorinated biphenyls possess oestrogen-mimicking properties and have been measured in human breast adipose tissue and in human milk. These enter the breast from varied environmental contamination of food, water and air, and due to their lipophilic properties can accumulate in breast fat. However, it is emerging that the breast is also exposed to a range of oestrogenic chemicals applied as cosmetics to the underarm and breast area. These cosmetics are left on the skin in the appropriate area, allowing a more direct dermal absorption route for breast exposure to oestrogenic chemicals and allowing absorbed chemicals to escape systemic metabolism. This review considers evidence in support of a functional role for the combined interactions of cosmetic chemicals with environmental oestrogens, pharmacological oestrogens, phyto-oestrogens and physiological oestrogens in the rising incidence of breast cancer.

Human milk research for answering questions about human health

Concerns regarding human milk in our society are diverse, ranging from the presence of environmental chemicals to the health of breastfed infants and the economic value of breastfeeding to society. The panel convened for the Technical Workshop on Human Milk Surveillance and Biomonitoring for Environmental Chemicals in the United States, held at the Hershey Medical Center, Pennsylvania State College of Medicine, on 24--26 September 2004, considered how human milk research may contribute to environmental health initiatives to benefit society. The panel concluded that infant, maternal, and community health can benefit from studies using human milk biomonitoring. Unlike other biological specimens, human milk provides information regarding exposure of the mother and breastfed infant to environmental chemicals. Some of the health topics relevant to this field of research include disorders of growth and development in infants, cancer origins in women, and characterization of the trend of exposure to environmental chemicals in the community. The research focus will determine the design of the study and the need for the collection of alternative biological specimens and the long-term storage of these specimens. In order to strengthen the ability to interpret study results, it is important to identify reference ranges for the chemicals measured and to control for populations with high environmental chemical exposure, because the amount of data on environmental chemical levels in human milk that is available for comparison is extremely limited. In addition, it will be necessary to validate models used to assess infant exposure from breastfeeding because of the variable nature of current models. Information on differences between individual and population risk estimates for toxicity needs to be effectively communicated to the participant. Human milk research designed to answer questions regarding health will require additional resources to meet these objectives.

Lack of effects of postnatal exposure to a mixture of aryl hydrocarbon-receptor agonists on the development of methylnitrosourea-induced mammary tumors in sprague-dawley rats

There are concerns that early life exposure to organochlorines, including aryl hydrocarbon receptor (AhR) agonists, may lead to long-term effects and increase the risk of developing breast cancer. Our objective was to test if postnatal exposure to a mixture of 2,3,7,8-tetrachlorodibenzodioxin (TCDD)-like chemicals would modulate the development of methylnitrosourea (MNU)-induced mammary tumors. Females received by gavage a mixture containing 3 non-ortho-polychlorinated biphenyls (PCBs), 6 polychlorinated dibenzodioxins (PCDDs), and 7 polychlorinated dibenzofurans (PCDFs), at 1, 5, 10, 15, and 20d of age. The doses were equivalent to 0, 1, 10, 100, or 1000 times the amount ingested through breast milk by a human infant during its first 24 d of life. Subgroups of 1000 x reated rats and controls were sacrificed at 21 d of age for assessment of mammary-gland development, cell death, and proliferation. Mammary-tumor development was assessed in MNU (30 mg/kg body weight ip at 50 days of age)-induced rats pre-exposed to the mixture (MNU-0, MNU-1, MNU-10, MNU-100, MNU-1000). Rats were sacrificed when their mammary tumors reached 1 cm in diameter, or when the rats reached > or = 32 wk of age. Mammary-gland whole mounts were analyzed with all palpable and microscopic lesions (n = 1563) histologically classified and grouped as benign, intraductal proliferations, or malignant. There were no marked effects on age at onset of puberty (vaginal opening) and estrous cyclicity. Despite a significant decrease in proliferating cell nuclear antigen (PCNA)-positive mammary cells in 1000 x treated 21-d-old rats, there were no long-term dose-response effects on mammary-gland morphology and tumor development. In conclusion, postnatal exposure to the mixture of AhR agonists had no significant effects on the development of MNU-initiated mammary tumors.

An unsupervised approach to identify molecular phenotypic components influencing breast cancer features

To discover a biological basis for clinical subgroupings within breast cancers, we applied principal components (PCs) analysis to cDNA microarray data from 36 breast cancers. We correlated the resulting PCs with clinical features. The 35 PCs discovered were ranked in order of their impact on gene expression patterns. Interestingly, PC 7 identified a unique subgroup consisting of estrogen receptor (ER); (+) African-American patients. This group exhibited global molecular phenotypes significantly different from both ER (-) African-American women and ER (+) or ER (-) Caucasian women (P < 0.001). Additional significant PCs included PC 4, correlating with lymph node metastasis (P = 0.04), and PC 10, with tumor stage (stage 2 versus stage 3; P = 0.007). These results provide a molecular phenotypic basis for the existence of a biologically unique subgroup comprising ER (+) breast cancers from African-American patients. Moreover, these findings illustrate the potential of PCs analysis to detect molecular phenotypic bases for relevant clinical or biological features of human tumors in general.

Pancreatic cancer mortality in China (1991-2000)

AIM: To describe the mortality rate of pancreatic cancer and its distribution in China during the period of 1991-2000.

METHODS: Based on the data of demography and death collected through China’s Disease Surveillance Point System (DSPS) over the period of 1991-2000, the distribution of death rate of pancreatic cancer was described in terms of age group, gender, calendar year, rural/urban residence and administrative district.

RESULTS: A total of 1619 death cases attributed to pancreatic cancer (975 men and 644 women) were reported by DSPS during 1991-2000. The reported, adjusted and age-standardized mortality rates increased from 1.46, 1.75, and 2.18 per 100000 populations in 1991 to 2.38, 3.06, and 3.26 per 100000 populations in 2000. The majority (69.62%) of the deaths of pancreatic cancer were seen in the age group of 60 years and older. The mortality rate was higher in men than in women, but the male to female death rate ratios decreased during the 10 years. Our data also showed that the death rate of pancreatic cancer in urban areas was about 2-4 fold higher than that in rural areas, and in Northeast and East China, the death rates were higher than those in the other 5 administrative districts.

CONCLUSION: The death rate due to pancreatic cancer was rising during the period of 1991-2000 and the peak mortality of pancreatic cancer might arrive in China.