Lifestyle, hormones, and risk of breast cancer

Active Molecular Network Discovery Links Lifestyle Variables to Breast Cancer in the Long Island Breast Cancer Study Project

A healthy lifestyle has been associated with decreased risk of developing breast cancer. Using untargeted metabolomics profiling, which provides unbiased information regarding lifestyle choices such as diet and exercise, we aim to identify the molecular mechanisms connecting lifestyle and breast cancer through network analysis. A total of 100 postmenopausal women, 50 with breast cancer and 50 cancer-free controls, were selected from the Long Island Breast Cancer Study Project (LIBCSP). We measured untargeted plasma metabolomics using liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Using the "enet" package, we retained highly correlated metabolites representing active molecular network (AMN) clusters for analysis. LASSO was used to examine associations between cancer status and AMN metabolites and covariates such as BMI, age, and reproductive factors. LASSO was then repeated to examine associations between AMN metabolites and 10 lifestyle-related variables including smoking, physical activity, alcohol consumption, meat consumption, fruit and vegetable consumption, and supplemental vitamin use. Results were displayed as a network to uncover biological pathways linking lifestyle factors to breast cancer status. After filtering, 851 "active" metabolites out of 1797 metabolomics were retained in 197 correlation AMN clusters. Using LASSO, breast cancer status was associated with 71 "active" metabolites. Several of these metabolites were associated with lifestyle variables including meat consumption, alcohol consumption, and supplemental β-carotene, B12, and folate use. Those metabolites could potentially serve as molecular-level biological intermediaries connecting healthy lifestyle factors to breast cancer, even though direct associations between breast cancer and the investigated lifestyles at the phenotype level are not evident. In particular, DiHODE, a metabolite linked with inflammation, was associated with breast cancer status and connected to β-carotene supplement usage through an AMN. We found several plasma metabolites associated with lifestyle factors and breast cancer status. Future studies investigating the mechanistic role of inflammation in linking supplement usage to breast cancer status are warranted.

Current and future applications of biomarkers in samples collected through minimally invasive methods for cancer medicine and population-based research

Despite advances in cancer medicine and research, invasive and potentially risky procedures such as biopsies, venous blood tests, imaging, colonoscopy, and pap smear tests are still primarily used for screening, staging, and assessing response to therapy. The development and interdisciplinary use of biomarkers from urine, feces, saliva, scent, and capillary blood collected with minimally invasive methods represents a potential opportunity for integration with biomarker analysis for cancers, both in clinical practice (e.g., in screening, treatment, and disease monitoring, and improved quality of life for patients) and population-based research (e.g., in epidemiology/public health, studies of social and environmental determinants, and evolutionary medicine). In this article, we review the scientific rationale, benefits, challenges, and potential opportunities for measuring cancer-related biomarkers in samples collected through minimally invasive methods.

Joint effect of particulate matter and cigarette smoke on women's sex hormones

BACKGROUND

Although relationships between exposure to air pollution and reproductive health are broadly studied, mechanisms behind these phenomena are still unknown. The aim of the study was to assess whether exposure to particulate matter (PM10) and tobacco smoking have an impact on menstrual profiles of 17β-estradiol (E2) and progesterone (P) and the E2/P ratio.

METHODS

Levels of sex hormones were measured daily in saliva during the entire menstrual cycle among 132 healthy, urban women. Exposure to smoking (active or passive) was assessed by questionnaire, whilst exposure to PM10 with municipal monitoring data.

RESULTS

During the early luteal phase, profiles of E2 were elevated among women with higher versus lower exposure to PM10 (p = 0.02, post-hoc tests). Among those who were exposed versus unexposed to tobacco smoking, the levels of mean E2 measured during the entire cycle were higher (p = 0.02). The difference in mean E2 levels between the group of joint exposure (i.e. to high PM10 and passive or active smoking) versus the reference group (low PM10, no smoking) was statistically significant at p = 0.03 (18.4 vs. 12.4 pmol/l, respectively). The E2/P ratios were higher among women with higher versus lower exposure to PM10 and this difference was seen only in the early luteal phase (p = 0.01, exploratory post-hoc tests).

CONCLUSIONS

We found that PM10 and tobacco smoking affect ovarian hormones independently and do not interact with each other. Both exposures appear to have estrogenic effects even though women's susceptibility to these effects differs across the menstrual cycle. We propose that the hormonal mechanisms are involved in observed relationships between air pollution and smoking with women's reproductive health.

Insights from evolutionarily relevant models for human ageing

As the world confronts the health challenges of an ageing population, there has been dramatically increased interest in the science of ageing. This research has overwhelmingly focused on age-related disease, particularly in industrialized human populations and short-lived laboratory animal models. However, it has become clear that humans and long-lived primates age differently than many typical model organisms, and that many of the diseases causing death and disability in the developed world are greatly exacerbated by modern lifestyles. As such, research on how the human ageing process evolved is vital to understanding the origins of prolonged human lifespan and factors increasing vulnerability to degenerative disease. In this issue, we highlight emerging comparative research on primates, highlighting the physical, physiological, behavioural and cognitive processes of ageing. This work comprises data and theory on non-human primates, as well as under-represented data on humans living in small-scale societies, which help elucidate how environment shapes senescence. Component papers address (i) the critical processes that comprise senescence in long-lived primates; (ii) the social, ecological or individual characteristics that predict variation in the pace of ageing; and (iii) the complicated relationship between ageing trajectories and disease outcomes. Collectively, this work provides essential comparative, evolutionary data on ageing and demonstrates its unique potential to inform our understanding of the human ageing process. This article is part of the theme issue 'Evolution of the primate ageing process'.

Energy Constraint as a Novel Mechanism Linking Exercise and Health

Humans and other species adapt dynamically to changes in daily physical activity, maintaining total energy expenditure within a narrow range. Chronic exercise thus suppresses other physiological activity, including immunity, reproduction, and stress response. This exercise-induced downregulation improves health at moderate levels of physical activity but can be detrimental at extreme workloads.

Oral contraceptives cause evolutionarily novel increases in hormone exposure: A risk factor for breast cancer

Background and objectives: In the evolutionary past, women spent most of their reproductive lives either pregnant or in lactational amenorrhea, and rarely menstruated. The current pattern of frequent menses, and the associated increase in endogenous hormonal exposure, has been implicated in the current breast cancer epidemic. It is not known, however, whether oral contraceptives further increase, or actually decrease, hormonal exposure over one menstrual cycle. Here, we examined variation in hormonal exposure across seven oral contraceptive (OC) formulations, and produced the first quantitative comparison of exogenous versus endogenous hormone exposure. Methodology: Data from 12 studies of serum estradiol (E2) and progesterone (P4) were aggregated to create a composite graph of endogenous hormone levels over one menstrual cycle in European or American women (age 19-40 years). Pharmacokinetic package insert data, also from Western women, were used to calculate exposures for hormones in seven different OC formulations. Endogenous and exogenous hormone levels were compared after adjusting for the relative binding affinity (RBA) of progestin to the progesterone receptor and ethinyl estradiol (EE) to the estrogen receptor. Results: After adjusting for RBA, median ethinyl estradiol exposure across 28 days in the OCs was 11.4 nmol/l, similar to median E2 exposure. One formulation, however, was 40% higher in ethinyl estradiol exposure relative to median endogenous estradiol. Median exposure from progestins in OCs (1496 nmol/l) was 4-fold higher than the median endogenous exposure from P4 (364 nmol/l). Exposure from OC progestins ranged from one sixtieth to 8-fold median endogenous P4 over 28 days. Conclusions and implications: Given that breast cancer risk increases with hormonal exposure, our finding that four widely prescribed formulations more than quadruple progestin exposure relative to endogenous progesterone exposure is cause for concern. As not all formulations produce the same exposures, these findings are pertinent to contraceptive choice. We also identify critical gaps in the provision of relevant data on pharmacokinetics and carcinogenicity by drug manufacturers.

Is health-related quality of life a suitable outcome measure for evaluating health promotion programmes?

This study describes results from a double blind randomised controlled trial which examined the efficacy of a primary care-based exercise promotion programme (the Health Walks Scheme). Quality of life data from the SF-36 questionnaire are presented from 260 previously sedentary participants randomly selected from a large GP practice (data are available for 72% at the 12-month follow-up). After 12 months, only 61% of participants in the health walks group were still classified as sedentary, compared with 73% in the control group who were simply given advice regarding exercise (p=0.05). There were no significant changes in the dimensions of the SF-36 questionnaire at 12 months. Those people who actually completed a health walk showed larger improvements in dimensions of the SF-36 (although these were also not significant). The appropriateness of quality of life outcome measures in health promotion trials is discussed in the light of the findings.

RANKL/RANK - from bone physiology to breast cancer

RANK and its ligand RANKL are key molecules in bone metabolism and are critically involved in pathologic bone disorders. Deregulation of the RANK/RANKL system is for example a main reason for the development of postmenopausal osteoporosis, which affects millions of women worldwide. Another essential function of RANK and RANKL is the development of a functional lactating mammary gland during pregnancy. Sex hormones, in particular progesterone, induce RANKL expression resulting in proliferation of mammary epithelial cells. Moreover, RANK and RANKL have been shown to regulate mammary epithelial stem cells. RANK and RANKL were also identified as critical mechanism in the development of hormone-induced breast cancer and metastatic spread to bone. In this review, we will focus on the various RANK/RANKL functions ranging from bone physiology, immune regulation, and initiation of breast cancer.

Relationships between biomarkers of inflammation, ovarian steroids, and age at menarche in a rural Polish sample

OBJECTIVES

To test the hypothesis that life history trade-offs between maintenance and reproductive effort would be evident through inverse associations between levels of a biomarker of inflammation [C-reactive protein (CRP)], and ovarian hormones. Associations between CRP and age at menarche were also explored.

METHODS

Urinary CRP, salivary progesterone, and estradiol were measured over one menstrual cycle from rural Polish women (n = 25), representing a natural fertility sample. Age of menarche was assessed through interview recall methods. We used minimum second-order Akaike Information Criteria as a means of multiple regression model selection, and repeated measures ANOVA to test cycle-dependent hypotheses.

RESULTS

Comparisons of individuals in high and low CRP tertiles revealed that those with high CRP had significantly lower progesterone (luteal P = 0.03, mid luteal P = 0.007) but not estradiol (follicular P = 0.21, luteal P = 0.15) concentrations through the menstrual cycle. However, when the age at menarche was included in the analysis, both age at menarche and urinary CRP were negatively associated with estradiol (R(2) = 0.44, P = 0.0007). Age at menarche and estradiol were the strongest negative predictors of CRP (R(2) = 0.52, P = 0.0001).

CONCLUSIONS

Inflammation itself may suppress ovarian function, or indicate immune challenges that lead to ovarian suppression. The timing of menarche may also influence adult inflammatory sensitivity and ovarian hormone concentrations. This lends support to existing models of trade-offs between maintenance and reproduction in women.

Evolutionary foundations for cancer biology

New applications of evolutionary biology are transforming our understanding of cancer. The articles in this special issue provide many specific examples, such as microorganisms inducing cancers, the significance of within-tumor heterogeneity, and the possibility that lower dose chemotherapy may sometimes promote longer survival. Underlying these specific advances is a large-scale transformation, as cancer research incorporates evolutionary methods into its toolkit, and asks new evolutionary questions about why we are vulnerable to cancer. Evolution explains why cancer exists at all, how neoplasms grow, why cancer is remarkably rare, and why it occurs despite powerful cancer suppression mechanisms. Cancer exists because of somatic selection; mutations in somatic cells result in some dividing faster than others, in some cases generating neoplasms. Neoplasms grow, or do not, in complex cellular ecosystems. Cancer is relatively rare because of natural selection; our genomes were derived disproportionally from individuals with effective mechanisms for suppressing cancer. Cancer occurs nonetheless for the same six evolutionary reasons that explain why we remain vulnerable to other diseases. These four principles-cancers evolve by somatic selection, neoplasms grow in complex ecosystems, natural selection has shaped powerful cancer defenses, and the limitations of those defenses have evolutionary explanations-provide a foundation for understanding, preventing, and treating cancer.

Total testosterone in young men is more closely associated than free testosterone with prostate cancer disparities

INTRODUCTION

Early adulthood has been suggested as the most relevant time to determine the influence of testosterone on prostate carcinogenesis. For a more detailed assessment of this hypothesis, the present study examined whether serum total or free testosterone in young men was more closely associated with prostate cancer disparities.

METHODS

A literature search was conducted for studies that reported both total and free testosterone levels for population samples of young men, along with prostate cancer incidences for the populations from which study populations were sampled. A previously developed analytical method was used to standardize the hormone levels of 19 population samples gathered from nine studies, and these standardized values were compared with disparities in prostate cancer incidence.

RESULTS

Population differences in total testosterone levels were significantly associated with prostate cancer disparities, r = 0.833, p = 0.001, as were population differences in free testosterone, r = 0.661, p = 0.027. After controlling for age differences, total and free testosterone remained associated with prostate cancer disparities, partial r = 0.888, p < 0.001, and partial r = 0.657, p = 0.039, respectively. A marginally significant difference existed in the strength of relationships between total and free testosterone with respect to prostate cancer disparities, with total testosterone exhibiting a stronger association, T(2) = 1.573, p = 0.077.

CONCLUSIONS

Across analyses, total testosterone demonstrated a more robust relationship than free testosterone with cancer disparities, which may suggest that total testosterone is the more sensitive biomarker for evaluating androgenic stimulation of the prostate gland.

Ovarian hormones and reproductive risk factors for breast cancer in premenopausal women: the Norwegian EBBA-I study

BACKGROUND

Ovarian hormones, parity and length of ‘menarche-to-first birth’ time interval are known risk factors for breast cancer, yet the associations between 17β-estradiol, progesterone and these reproductive factors remain unclear.

METHODS

A total of 204 women (25–35 years) who participated in the Norwegian EBBA-I study collected daily saliva samples for one complete menstrual cycle, and filled in a reproductive history questionnaire. Anthropometry was measured and saliva samples were analyzed for ovarian hormones. Associations between parity, the interval and ovarian hormones, and effects of hormone-related lifestyle factors were studied in linear regression models.

RESULTS

Mean age was 30.7 years, and age of menarche 13.1 years. Parous women had on average 1.9 births, and age at first birth was 24.5 years. No association was observed between parity and ovarian steroids. In nulliparous women, higher waist circumference (≥77.75 cm) and longer oral contraceptive (OC) use (≥3 years) were associated with higher levels of 17β-estradiol. Short (<10 years) versus long (>13.5 years) ‘menarche-to-first birth’ interval was associated with higher overall mean (P_trend = 0.029), 47% higher maximum peak and 30% higher mid-cycle levels of 17β-estradiol. We observed a 2.6% decrease in overall mean salivary 17β-estradiol with each 1-year increase in the interval.

CONCLUSIONS

Nulliparous women may be more susceptible to lifestyle factors, abdominal overweight and past OC use, influencing metabolic and hormonal profiles and thus breast cancer risk. Short time between ‘menarche-to-first birth’ is linked to higher ovarian hormone levels among regularly cycling women, suggesting that timing of first birth is related to fecundity.

Prevalence of menstrual pain in relation to the reproductive life history of women from the Mayan rural community

BACKGROUND

The prevalence of menstrual pain in Western societies is relatively high and has been shown to be related to many factors (e.g. age, menarche age, parity, menstrual cycle regularity, cigarette smoking, dietary habits). However, less data are available for traditional societies, within which there are, presumably, not as many potentially disturbing factors that could influence menstrual symptoms as in Western societies.

AIM

The study seeks to determine the prevalence of dysmenorrhoea, and the factors related to menstrual pains in women with natural fertility (i.e. without hormonal forms of contraception).

SUBJECTS AND METHODS

177 non-smoking women between 18 and 45 years of age living in one Mayan village (Yaxcaba, Yucatan, Mexico) were the subjects of this study. The method of logistic regression was used with the dichotomous dependent variable being the presence or absence of menstrual pain together with such independent variables as age, age at menarche, number of pregnancies, age when giving birth to the first child, the weight at interview and BMI.

RESULTS

The general prevalence of the menstrual pains was 28%. There was only one variable influencing dysmenorrhoea, namely the age at which women give birth to their first children. Those mothers who gave birth to their first child at an earlier age (at mean age of 19.4 vs 21.1 years) had a lower prevalence of dysmenorrhoea.

CONCLUSION

In the studied traditional society the main factor related to menstrual pain was the age at which woman first gave birth. It is hypothesized that an earlier start to reproductive life in some way decreases the sensitivity of the uterus to prostaglandins.

Adult height, insulin, and 17beta-estradiol in young women

BACKGROUND

Adult height and insulin are thought to modify the development of breast cancer. However, little is known about the association between height and 17beta-estradiol, a key factor in breast carcinogenesis, and whether insulin modifies such an association.

METHODS

Among 204 healthy women, ages 25 to 35 years, who participated in the Energy Balance and Breast Cancer Aspect I study, adult height (in centimeters) and fasting serum concentrations of insulin (pmol/L) were measured. 17beta-Estradiol concentrations were measured in daily saliva samples throughout an entire menstrual cycle through RIA. Age and multivariate linear regression models were used to study the association between adult height and 17beta-estradiol levels throughout an entire menstrual cycle and whether serum levels of fasting insulin may modify such an association.

RESULTS

The women had a mean age of 30.7 years, adult height of 166.9 cm, and serum insulin of 85.7 pmol/L. For each increase of one SD in insulin levels in the upper tertile of adult height, the adjusted level of 17beta-estradiol increased by 3.1 pmol/L (95% confidence interval, 1.1-5.2), equivalent to a 17.3% higher mean average concentration of 17beta-estradiol. Women with an adult height > or =170 cm (upper tertile) and insulin levels >101 pmol/L (upper quartile) experienced, on average, 41% higher 17beta-estradiol levels throughout the entire menstrual cycle compared with women with the same adult height and insulin levels <101 pmol/L.

CONCLUSION

Our findings support that premenopausal levels of 17beta-estradiol vary in response to adult height and insulin levels, of possible importance for breast cancer risk.

Low estradiol levels in women of reproductive age having low sleep variation

Higher exposure to light at night, for example, owing to night shift work or decrease in sleep duration, may suppress melatonin production, which in turn may increase the reproductive hormone levels. High levels of steroid hormones, especially estrogens, may be associated with an increase of the breast cancer risk. This study investigated whether variation in the sleep duration during one entire menstrual cycle corresponds to estradiol saliva concentrations in healthy, urban women of reproductive age. During 2000-2001, 95 regularly menstruating women aged 24-36 in Poland collected daily saliva samples for one entire menstrual cycle. Saliva samples were analyzed for concentration of 17-beta estradiol (E2) using radio immunoassay. Information on the number of hours of sleep per night (sleep duration) was collected daily by questionnaires for one entire menstrual cycle. Using covariance analysis, after adjustments for sleep duration, we documented a positive relationship between the sleep variation (sleep coefficient of variation) and E2 levels in women of reproductive age. Mean levels of E2 differed significantly in women from the lowest sleep coefficient of variation quartile (13.93 pmol/l) in comparison with other quartiles (22.35 pmol/l), (P<0.001). The low sleep variation group, that is, the women who sleep regularly, had mean E2 levels 60% lower than other groups. These results suggest that sleep variation significantly correlates with E2 levels, whereas sleep duration does not show a statistically significant relationship. This study suggests that sleep variation may influence endogenous estrogens, which is of importance for risk of breast cancer.

Interpopulation, interindividual, intercycle, and intracycle natural variation in progesterone levels: a quantitative assessment and implications for population studies

Methodological challenges in studying sex steroid hormones in premenopausal women result from the existence of variation at three levels: among women from the same population, among menstrual cycles recorded for women at different times of the year, and among days of the same cycle. We partitioned, for a Polish rural population, the natural, nonpathological, variation in salivary progesterone concentrations (measured during 14 days of the luteal phase) into the intracycle component (which accounts for 65% of the total variation) and the among-cycle component (the remaining 35% of the total variation). Out of the among-cycle variation in salivary progesterone, as much as 46% is expressed as differences among individual women (interindividual component); the remaining 54% of variation is due to differences among cycles of individual women (intercycle, within-women component). Such intercycle variation is probably caused by a seasonality of agricultural workload and is much higher than in nonseasonal, industrial populations. We also used bootstrap analyses to generate heuristic recommendations for choosing sample sizes of the number of subjects, number of cycles per woman, and number of days per cycle. Studies in populations with seasonal lifestyles should rely on measurements of at least three cycles per woman. Given the substantial intracycle amplitude in hormone levels to reliably assess biologically and medically relevant variation in ovarian function, at least 7-8 days/cycle should be measured.

Progesterone receptor polymorphisms and risk of breast cancer: results from two Australian breast cancer studies

Association studies aimed at identifying breast cancer susceptibility variants in the progesterone receptor (PGR) gene have been previously reported in the literature with conflicting results, ranging from a protective effect conferred by the PROGINS allele in German Caucasian women, to an increased risk for the leucine variant of the Val660Leu (rs1042838) polymorphism in East Anglian cases. We report the results of genotype and haplotype analyses of five PGR polymorphisms, +44C/T (rs518162), +331G/A (rs10895068), V660L (rs1042838), H770H (rs1042839) and Q886Q (rs500760), conducted on 1,847 Australian breast cancer cases (including 276 cases from a cohort of multiple-case breast cancer families) and 833 controls. Genotype and haplotype analyses of the five polymorphisms showed no evidence of an association with breast cancer (p>0.3). We also conducted a meta-analysis of the V660 L (rs1042838) polymorphism on our and six other published studies including 10,205 cases and 11,320 controls. Compared to the VV homozygotes, VL heterozygotes and LL homozygotes were associated with a non-significant increased risk for breast cancer [Odds ratio (OR)VL, 1.06; 95% confidence intervals (95% CI), 0.97-1.15, ORLL, 1.05; 95% CI, 0.75-1.49]. Analysis of a per-leucine allele risk under a codominant model, however, suggested a significant leucine-allele dose effect, ORper-L, 1.07; 95% CI, 1.02-1.13, p=0.01. We conclude that the leucine allele of the V660L SNP may be associated with a small increase in breast cancer risk, while the other four PGR SNPs, +44C/T (rs518162), +331G/A (rs10895068), H770H (rs1042839) and Q886Q (rs500760), do not substantially increase breast cancer risk.

Childhood conditions influence adult progesterone levels

BACKGROUND

Average profiles of salivary progesterone in women vary significantly at the inter- and intrapopulation level as a function of age and acute energetic conditions related to energy intake, energy expenditure, or a combination of both. In addition to acute stressors, baseline progesterone levels differ among populations. The causes of such chronic differences are not well understood, but it has been hypothesised that they may result from varying tempos of growth and maturation and, by implication, from diverse environmental conditions encountered during childhood and adolescence.

METHODS AND FINDINGS

To test this hypothesis, we conducted a migrant study among first- and second-generation Bangladeshi women aged 19-39 who migrated to London, UK at different points in the life-course, women still resident in Bangladesh, and women of European descent living in neighbourhoods similar to those of the migrants in London (total n = 227). Data collected included saliva samples for radioimmunoassay of progesterone, anthropometrics, and information from questionnaires on diet, lifestyle, and health. Results from multiple linear regression, controlled for anthropometric and reproductive variables, show that women who spend their childhood in conditions of low energy expenditure, stable energy intake, good sanitation, low immune challenges, and good health care in the UK have up to 103% higher levels of salivary progesterone and an earlier maturation than women who develop in less optimal conditions in Sylhet, Bangladesh (F9,178 = 5.05, p < 0.001, standard error of the mean = 0.32; adjusted R(2) = 0.16). Our results point to the period prior to puberty as a sensitive phase when changes in environmental conditions positively impact developmental tempos such as menarcheal age (F2,81 = 3.21, p = 0.03) and patterns of ovarian function as measured using salivary progesterone (F2,81 = 3.14, p = 0.04).

CONCLUSIONS

This research demonstrates that human females use an extended period of the life cycle prior to reproductive maturation to monitor their environment and to modulate reproductive steroid levels in accordance with projected conditions they might encounter as adults. Given the prolonged investment of human pregnancy and lactation, such plasticity (extending beyond any intrauterine programming) enables a more flexible and finely tuned adjustment to the potential constraints or opportunities of the later adult environment. This research is the first, to our knowledge, to demonstrate a postuterine developmental component to variation in reproductive steroid levels in women.

Habitual physical activity and estradiol levels in women of reproductive age

Variation in the risk of breast cancer observed among women and among populations may be explained by variation in lifetime exposure to estrogens. The suppressive effect of exercise on estradiol levels in women is well documented, but it is unknown whether habitual (i.e. typical daily) physical activity has a similar effect. Epidemiological data suggest that physical activity is one of the few modifiable factors capable of reducing the risk of breast cancer in women. We investigated whether variation in the amount of habitual activity corresponds to variation in estradiol levels in women of reproductive age. One hundred and thirty-nine regularly menstruating women 24-37 years of age collected daily saliva samples for one complete menstrual cycle and kept a daily log of physical activity. Saliva samples were analyzed for concentration of estradiol. We observed a negative relationship between habitual physical activity and salivary levels of estradiol. Mean estradiol was 21.1 pmol/l in the low, 17.9 pmol/l in the moderate and 16.6 pmol/l in the high activity group (all pairwise differences were statistically significant at P<0.009). A strong association exists between physical activity and levels of estradiol among women of reproductive age. A modern lifestyle, characterized by reduced physical activity, may therefore contribute to a rise in the levels of estradiol produced during menstrual cycles and thus to higher cumulative lifetime exposure to estradiol, resulting in a higher risk of breast cancer.

High tea consumption diminishes salivary 17beta-estradiol concentration in Polish women

We hypothesized that among reproductive-age women consuming large quantities of tea, the production of estradiol would be suppressed. It has been shown that catechins and theaflavines, the major constituents of tea, inhibit aromatase, an enzyme which catalyses the conversion of androgens to oestrogens. Our study included Polish women living in urban (n 61) and rural (n 48) areas. Women collected daily saliva samples for one complete menstrual cycle and filled out dietary questionnaires. Saliva samples were analysed by RIA for concentration of 17beta-estradiol (E2). Women with high (above the median) average daily consumption of black tea had reduced levels of salivary E2 in comparison with women who drank less black tea (below the median). This effect was observed within the whole study group, as well as separately within urban (P=0.0006) and rural (P=0.013) groups. High intake of the sum of subclasses of tea catechins and epigallocatechin gallate, assessed using the United States Department of Agriculture database (http://www.nal.usda.gov), was also associated with lower concentrations of E2 within all women (P=0.01 and P=0.0001, respectively) and within the urban group (P=0.0001 and P=0.004, respectively). Similar relationships were observed between the sum of subclasses of theaflavines and thearubigines and E2 levels for the whole group (P=0.002) and for urban women (P=0.02). Women with high consumption of tea had lower levels of E2 concentration throughout the entire menstrual cycle. These results may have implications for reducing hormone-related cancer risk by a relatively easy dietary intervention.

Body mass, depressive symptoms and menopausal status: An examination of the “Jolly Fat” hypothesis

PURPOSE

Estrogens are linked with depression due to their ability to alter the function of the serotonin neural systems. We hypothesize that postmenopausal women should have a higher degree of depressive symptoms than premenopausal women. Further, because estrogen levels in postmenopausal women positively correlate with body fat, we hypothesize that there is an inverse relationship between body fat and depressive symptoms among postmenopausal women.

METHODS

We enrolled 1156 Polish urban women aged 45 to 64 in a cross-sectional study. Depressive symptoms were assessed by the Center for Epidemiologic Studies-Depression Scale (CES-D) scale. Menopausal status and education level was assessed by a standardized questionnaire.

MAIN FINDINGS

Postmenopausal women had higher mean CES-D scores of depressive symptoms than premenopausal women (14.4 versus 13.2 respectively, p = .018). Both among pre- and postmenopausal women, those with higher education had lower scores of depressive symptoms. In addition, in postmenopausal women with lower education an inverse relationship was observed between body mass index (BMI) and depressive symptoms: a higher BMI was associated with a lower score of depressive symptoms (p = .009). Such a relationship was not present among premenopausal women or women who were postmenopausal but better educated.

CONCLUSIONS

This study indicates that menopausal status is related to differences in the degree of occurrence of depressive symptoms. Our results support the "Jolly Fat" hypothesis for postmenopausal women with lower education, namely, a higher BMI is associated with lower score of depressive symptoms.

High ponderal index at birth predicts high estradiol levels in adult women

Inter-individual variation in levels of sex hormones results from differences in genetic, developmental, and environmental factors. We tested a hypothesis that programming of the fetal neuroendocrine axis may predispose some women to produce higher levels of steroid hormones during their menstrual cycles as adults. One hundred forty-five regularly menstruating 24- to 36- year-old women collected daily saliva samples for one menstrual cycle. Data on women's birth weights and birth lengths were obtained from medical records. A positive relationship was observed between ponderal index at birth (an indicator of nutritional status, calculated as birth weight/(birth length)(3)) and levels of estradiol (E2) in menstrual cycles, after controlling for potential confounding factors. Mean E2 was 16.4 pmol/l in the low ponderal index tertile, 17.3 pmol/l in the moderate ponderal index tertile, and 19.6 pmol/l in the high ponderal index tertile (the high ponderal index group had significantly higher E2 than both low and moderate ponderal index groups, P=0.0001). This study shows a positive association between ponderal index recorded for women at birth and levels of E2 measured during their menstrual cycles as adults. This suggests that conditions during fetal life influence adult production of reproductive hormones and may contribute to inter-individual variation in reproductive function. In addition, because large size at birth is one of the factors linked with an increased risk of breast cancer, our findings provide a physiological link for the observed positive relationship between indicators of energetic conditions during fetal growth and breast cancer in women.

Energetic factors and seasonal changes in ovarian function in women from rural Poland

Female mammals can optimize their fitness by temporal suppression of reproductive function in response to unfavorable environmental conditions. Since reproduction is energetically demanding for a human female, ovarian function is expected to be sensitive to factors influencing energy availability and metabolism. Dieting and exercise in women from industrial countries, and low-calorie diet and workload in women from developing countries, are often associated with ovarian suppression. This study shows that in Polish rural women seasonal changes in workload correlate with seasonal changes in indices of ovarian function (progesterone measured in saliva samples collected daily for six menstrual cycles for each subject). Mean levels of energy expenditure of the most work demanding weeks of the summer exceeded mean levels of energy expenditure during winter by 37%. Energy intake in this population was sufficient throughout the year. During the summer, when physical work was most intense, low values of progesterone levels were observed (178.2 pmol/L in July and 182.2 pmol/L in August), indicating ovarian suppression. Mean progesterone levels rose to 234.6 pmol/L in October when levels of energy expenditure were lower due to cessation of harvest-related activities. As indicated by several causal models tested through path analysis, energy expenditure was the only variable responsible for suppressed progesterone levels during the summer. Variables describing the nutritional status and energy balance did not correlate significantly with progesterone levels; neither body weight nor body fat or seasonal changes of these variables seem to influence ovarian function in this population. Thus work-related energy expenditure does not need to lead to negative energy balance in order to cause suppression of reproductive function in women.

Metabolic abnormalities (hypertension, hyperglycemia and overweight), lifestyle (high energy intake and physical inactivity) and endometrial cancer risk in a Norwegian cohort

Since high energy intake, inactivity, hypertension and diabetes are linked to obesity and an unfavorable hormonal profile, we wanted to test whether energy intake, physical activity, blood pressure and serum glucose are related to the risk of endometrial cancer independent of the body mass index (BMI). A cohort of 24,460 women, aged 20-49 years, attended a Norwegian health screening twice during 1974-1981; they answered questions about diet, physical activity and chronic diseases, and their height, weight, blood pressure and non-fasting serum glucose were measured. By the end of 1996, during 15.7 years of follow-up, 130 cases of endometrial carcinomas were identified. The relative risks (RRs) for endometrial cancer were estimated in proportional hazards models including potentially confounding factors. Obese women (BMI > or = 30 kg/m(2)) were at 2.6 times increased risk of endometrial cancer compared to normal weight women (BMI < 25 kg/m(2)) (RR = 2.57, 95%CI = 1.61-4.10). Among overweight women (BMI > or = 25 kg/m(2)), non-fasting serum glucose in the upper quartile vs. in the lower quartile was associated with a 2.4 times increase in risk (RR = 2.41, 95%CI = 1.08-5.37), whereas among obese women, blood pressure above 140/90 mmHg vs. below 140/90 mmHg in both surveys was associated with a 3.5 times increase in risk (RR = 3.47, 95%CI = 1.24-9.70). Especially in women younger than 50 years, high energy intake (5,044-6,401 kJ/day) conferred higher risk compared to low energy intake (< 4266 kJ/day) (RR = 3.40, 95%CI = 1.52-7.60). Increasing recreational activity tended to be protective. Among obese women with non-sedentary jobs at both screenings, RR declined to 0.18 (95%CI = 0.05-0.62) as the level of sustained occupational activity increased (p(trend) = 0.03). Our results suggest that inactivity and high energy intake are major risk factors for endometrial cancer independent of BMI, and that hypertension and relative hyperglycemia are significant markers of risk, especially among the heaviest women.

Transition in cancer patterns among Turks residing in Germany

Cancer mortality among the 2.1 million Turks residing in Germany is assumed to change from a pattern typical for a developing country towards one of an industrialised country. To test this hypothesis, we compared age-standardised cancer mortality rates among Turkish residents and (West) Germans using death registration data. In addition, we assessed proportional cancer incidence ratios among Turkish cases (n=144) in a German population-based cancer registry. All-cancer mortality 1992-1997 (per 100000) was 34.8 (n=4192) among Turkish men (Germans: 72.3) and 21.5 (n=1862) among Turkish women (Germans: 52.4). Over time, gastric and lung cancer mortality increased among Turkish men, as did breast cancer mortality among Turkish women. The proportional cancer incidence (PCIR) for stomach cancer among men was 2.9 (95% Confidence Interval (CI): 1.7-4.8), and that for breast cancer among women was 0.7 (95% CI: 0.4-1.1). Turks had an increased proportional incidence ratio for non-Hodgkin's lymphoma. Our findings partly support a transition of cancer patterns among Turks in Germany.

Diet and environmental carcinogenesis in breast/gynaecological cancers

This paper reports on recent advances on the relation between diet, other environmental factors and breast and gynaecological cancers. Despite considerable research the issue remains still unsettled. The protective effect of a diet rich in vegetables and fruit, and thus selected (antioxidant) micronutrients, is not consistently reported in various studies. The possible relationship between fats and breast and female genital tract neoplasms also remains unconfirmed, while the potential benefits of physical activity remains unquantified. Alcohol appears to be related to the risk of breast cancer and overweight is associated with post-menopausal breast cancer and is strongly related to the risk of endometrial cancer.

Time travel with Oliver Twist--towards an explanation foa a paradoxically low mortality among recent immigrants

First-generation immigrant populations in industrialized countries frequently have a lower mortality than the host population, a finding that is unexpected and often dismissed as the result of bias. We propose an alternative explanation for a real, albeit temporal, mortality advantage. We base our argument on two premises: First, that there are differences in the progression of the health transition between the immigrants' countries of origin and industrialized host countries; and, second, that there are differences in the speed at which changes in mortality from various causes occur after migration. Mortality from treatable communicable and maternal conditions, still high in many countries of origin, quickly declines to levels close to those of the host country. Mortality from ischaemic heart disease, the most common cause of death in the host countries, takes years or decades to rise to comparable heights. This is because of the time lag between increases in risk factor levels and an increased risk of coronary death. Hence, first-generation immigrants may initially experience a lower mortality than the host population, a point that has so far been under-appreciated in discussions of immigrant mortality. After adopting a western lifestyle immigrants face an increasing risk of ischaemic heart disease. The increase occurs on top of a persisting risk from conditions associated with childhood deprivation, e.g. stomach cancer and stroke--the unfinished agenda of the health transition that immigrants experience.

Soy for breast cancer survivors: a critical review of the literature

A variety of health benefits, including protection against breast cancer, have been attributed to soy food consumption, primarily because of the soybean isoflavones (genistein, daidzein, glycitein). Isoflavones are considered to be possible selective estrogen receptor modulators but possess nonhormonal properties that also may contribute to their effects. Concern has arisen over a possible detrimental effect of soy in breast cancer patients because of the estrogen-like effects of isoflavones. Genistein exhibits a biphasic effect on the growth of MCF-7 cells in vitro, stimulating proliferation at low concentrations but inhibiting it at high concentrations. In ovariectomized athymic mice implanted with MCF-7 cells, both genistein and soy protein stimulate tumor growth in a dose-dependent manner. In contrast, in intact mice fed estrogen, genistein inhibits tumor growth. Although two studies in premenopausal women suggested that soy exerts estrogenic-like effects on breast tissue, recently conducted year-long studies indicated that isoflavone supplements do not affect breast tissue density in premenopausal women and may decrease density in postmenopausal women. These latter effects are opposite to those of hormone replacement therapy (HRT). Importantly, substantial data suggest that the progestogen, not the estrogen, component of HRT increases risk of developing breast cancer. Furthermore, recently conducted studies have failed to find that even HRT reduces survival in breast cancer patients. Overall, the data are not impressive that the adult consumption of soy affects the risk of developing breast cancer or that soy consumption affects the survival of breast cancer patients. Consequently, if breast cancer patients enjoy soy products, it seems reasonable for them to continue to use them.