Age at menarche, age at menopause, height and obesity as risk factors for breast cancer: associations and interactions in an international case-control study

Estimating Risk of Breast Cancer Occurrences at Different Ages: Application of Survival Techniques

Background: Awareness is the primary means to control breast cancer occurrence. The purpose of the present work is to study the risk of breast cancer occurrence in different age group, for the study area, Assam, India, by means of survival analysis techniques. Methods: Survival and hazard functions are key concepts in survival analysis for describing the distribution of event times. In the present research a new individialized model has been proposed for cumulative hazard function, taking gamma probability distribution as probability distribution of breast cancer occurrences. Kaplan Meier Survival method has been applied to find out the probability of diseases occurrence in the early menarche and late menarche group. The data used for implementation were collected from the Record Department of a prime local cancer institute, for the period 2010-2012. The information for the risk factor age at menarche were collected from the patients registered during August 2011 to February 2012. Results: The study reveals that in the study area, cumulative hazard of the women belonging to 35 to 50 years is higher than the early and late aged women. The cumulative hazard plot with shape parameter 0.5, 1 and 10 shows that cumulative risk for early aged women are greater than the late age women but when this values is increased from 10, the opposite trend is observed. Further, the median age of disease occurrence among early menarche group is 52 years and for late menarche it is 54 years. Conclusion: The model developed could successfully point out the age group for women lying at higher risk of breast cancer occurrence. Additionally the important risk factor, age at menarche, was effectively applied to supplement to this calculation. It is hoped that practical use of this method would enhance not only awareness but also early detection of the said disease.

Ethanol Enhances Estrogen Mediated Angiogenesis in Breast Cancer

Angiogenesis, a highly regulated process, is exploited by tumors like breast cancer to ensure a constant supply of oxygen and nutrients and is key for tumor survival and progression. Estrogen and alcohol independently have been observed to contribute to angiogenesis in breast cancer but their combinatorial effects have never been evaluated. The exact mechanism by which estrogen and alcohol contribute to breast cancer angiogenesis remains to be elucidated. In this study, we defined the in vitro effects of the combination of estrogen and alcohol in breast cancer angiogenesis using the tubulogenesis and scratch wound assays. Conditioned media, generated by culturing the murine mammary cancer cell line, TG1-1, in estrogen and ethanol, enhanced tubule formation and migration as well as modulated the MAP Kinase pathway in the murine endothelial cell line, SVEC4-10. Additionally, estrogen and ethanol in combination enhanced the expression of the pro-angiogenic factors VEGF, MMP-9, and eNOS, and modulated Akt activation. These observations suggest that TG1-1 cells secrete pro-angiogenic molecules in response to the combination of estrogen and ethanol that modulate the morphological and migratory properties of endothelial cells. The data presented in this study, is the first in attempting to link the cooperative activity between estrogen and ethanol in breast cancer progression, underscoring correlations first made by epidemiological observations linking the two.

A case-control study of breast cancer risk factors in 7,663 women in Malaysia

BACKGROUND

Breast cancer risk factors have been examined extensively in Western setting and more developed Asian cities/countries. However, there are limited data on developing Asian countries. The purpose of this study was to examine breast cancer risk factors and the change of selected risk factors across birth cohorts in Malaysian women.

METHODS

An unmatched hospital based case-control study was conducted from October 2002 to December 2016 in Selangor, Malaysia. A total of 3,683 cases and 3,980 controls were included in this study. Unconditional logistic regressions, adjusted for potential confounding factors, were conducted. The breast cancer risk factors were compared across four birth cohorts by ethnicity.

RESULTS

Ever breastfed, longer breastfeeding duration, a higher soymilk and soy product intake, and a higher level of physical activity were associated with lower risk of breast cancer. Chinese had the lowest breastfeeding rate, shortest breastfeeding duration, lowest parity and highest age of first full term pregnancy.

CONCLUSIONS

Our study shows that breastfeeding, soy intake and physical activity are modifiable risk factors for breast cancer. With the increasing incidence of breast cancer there is an urgent need to educate the women about lifestyle intervention they can take to reduce their breast cancer risk.

Impact of age at menarche on obesity and glycemic control in Japanese patients with type 2 diabetes: Fukuoka Diabetes Registry

AIMS/INTRODUCTION

A younger age at menarche is associated with obesity and type 2 diabetes in adult life. The impact of early-onset menarche on obesity and glycemic control in type 2 diabetes has not been investigated. The present study examined the relationship between age at menarche and obesity and glycemic control in type 2 diabetes.

MATERIALS AND METHODS

A total of 2,133 patients with type 2 diabetes aged ≥20 years were divided into groups according to age at menarche (≤11, 12, 13, 14 and ≥15 years). A retrospective cohort study examined the association of menarcheal age with adiposity and hemoglobin A1c .

RESULTS

Age at menarche was inversely associated with body mass index (BMI) and abdominal circumference (P < 0.001). Each 1-year decrease in age at menarche was associated with a 0.25-kg/m2 and 0.6-cm increase in BMI and abdominal circumference, respectively, using a multivariate-adjusted model. Odds ratios for obesity and abdominal obesity significantly increased in participants with age at menarche ≤11 years after multivariable adjustments when age at menarche of 13 years was used as the reference (odds ratio 1.95, 95% CI 1.33-2.88, odds ratio 1.95, 95% CI 1.32-2.87, respectively). Younger age at menarche was significantly associated with higher hemoglobin A1c (P < 0.001); however, the association was not statistically significant after adjusting for BMI.

CONCLUSIONS

Age at menarche of ≤11 years was associated with obesity after adjusting for confounding factors, and poor glycemic control associated with high BMI in type 2 diabetes. Age at menarche should be considered during clinical assessments.

Breast Cancer: Metastasis, Molecular Subtypes, and Overweight and Obesity in Veracruz, Mexico

INTRODUCTION

We assessed the association between overweight, obesity, and morbid obesity with the incidence of the most aggressive breast cancer subtypes in women.

METHODS AND MATERIALS

A cross-sectional study was performed. We conducted a record review to identify the following aspects: body mass index, sociodemographic features, tumor characteristics, and reproductive and molecular aspects. Descriptive statistics and univariate analysis were performed to identify the association between the molecular subtypes and the study variables. In addition, we used multivariate analysis to identify the association between obesity and the presence of metastatic lymph nodes.

RESULTS

We included 1446 women with an average age of 52.5 ± 12.1 years. Of the 1446 patients, 47% were premenopausal and 75% were overweight. Univariate analysis indicated a statistically significant association between obesity and advanced disease stage, as well as nulliparity and multiparity. Similar results were found for women with morbid obesity. Model 1 of the multivariate analysis showed an association between the presence of metastatic lymph nodes and obesity (odds ratio [OR], 1.6; P = .008) and histologic grade 2 or 3 (OR, 2.4; P = .003). Using model 2, an association was identified between an advanced disease stage and 2 factors: morbid obesity (OR, 1.9; P = .02) and positive human epidermal growth factor receptor 2 (OR, 1.8; P = .045).

CONCLUSION

We found that obesity is associated with the more advanced stages of breast cancer. Further studies are needed to evaluate the role of obesity in breast cancer progression in women.

Age at puberty and risk of asthma: A Mendelian randomisation study

BACKGROUND

Observational studies on pubertal timing and asthma, mainly performed in females, have provided conflicting results about a possible association of early puberty with higher risk of adult asthma, possibly due to residual confounding. To overcome issues of confounding, we used Mendelian randomisation (MR), i.e., genetic variants were used as instrumental variables to estimate causal effects of early puberty on post-pubertal asthma in both females and males.

METHODS AND FINDINGS

MR analyses were performed in UK Biobank on 243,316 women using 254 genetic variants for age at menarche, and on 192,067 men using 46 variants for age at voice breaking. Age at menarche, recorded in years, was categorised as early (<12), normal (12-14), or late (>14); age at voice breaking was recorded and analysed as early (younger than average), normal (about average age), or late (older than average). In females, we found evidence for a causal effect of pubertal timing on asthma, with an 8% increase in asthma risk for early menarche (odds ratio [OR] 1.08; 95% CI 1.04 to 1.12; p = 8.7 × 10(-5)) and an 8% decrease for late menarche (OR 0.92; 95% CI 0.89 to 0.97; p = 3.4 × 10(-4)), suggesting a continuous protective effect of increasing age at puberty. In males, we found very similar estimates of causal effects, although with wider confidence intervals (early voice breaking: OR 1.07; 95% CI 1.00 to 1.16; p = 0.06; late voice breaking: OR 0.93; 95% CI 0.87 to 0.99; p = 0.03). We detected only modest pleiotropy, and our findings showed robustness when different methods to account for pleiotropy were applied. BMI may either introduce pleiotropy or lie on the causal pathway; secondary analyses excluding variants associated with BMI yielded similar results to those of the main analyses. Our study relies on self-reported exposures and outcomes, which may have particularly affected the power of the analyses on age at voice breaking.

CONCLUSIONS

This large MR study provides evidence for a causal detrimental effect of early puberty on asthma, and does not support previous observational findings of a U-shaped relationship between pubertal timing and asthma. Common biological or psychological mechanisms associated with early puberty might explain the similarity of our results in females and males, but further research is needed to investigate this. Taken together with evidence for other detrimental effects of early puberty on health, our study emphasises the need to further investigate and address the causes of the secular shift towards earlier puberty observed worldwide.

Childhood and adolescent phenol and phthalate exposure and the age of menarche in Latina girls

BACKGROUND

The age of menarche has been associated with metabolic and cardiovascular disease, as well as cancer risk. The decline in menarcheal age over the past century may be partially attributable to increased exposure to endocrine disrupting chemicals (EDCs).

METHODS

We assessed the influence of 26 phenol and phthalate biomarkers on the timing of menarche in a longitudinal cohort of Chilean girls. These EDCs were quantified in urine collected prior to the onset of breast development (Tanner 1; B1), and during adolescence (Tanner 4; B4). Multivariable accelerated failure time (AFT) models were used to analyze associations between biomarker concentrations and the age of menarche adjusting for body mass index (BMI) Z-score and maternal education, accounting for within-subject correlation.

RESULTS

Several biomarkers were significantly associated with the age at menarche; however, these associations were dependent on the timing of biomarker assessment. A log(ng/ml) increase in B1 concentrations of di(2-ethylhexyl) phthalate biomarkers was associated with later menarche (hazard ratio (HR): 0.77; 95% CI: 0.60, 0.98), whereas higher B1 concentrations of 2,5-dichlorophenol and benzophenone-3 were associated with earlier menarche (HR: 1.13; 95% CI: 1.01, 1.27; HR: 1.17; 95% CI: 1.06, 1.29, respectively). Elevated B4 concentrations of monomethyl phthalate were similarly associated with earlier menarche (HR: 1.30; 95% CI: 1.10, 1.53). The impact of monoethyl phthalate and triclosan concentrations on pubertal timing were significantly modified by BMI Z-score. Higher monoethyl phthalate and triclosan concentrations were associated with earlier menarche among overweight or obese girls, but not among those that were normal weight.

CONCLUSIONS

This study identifies modulation of sexual maturation by specific EDC biomarkers in Latina girls.

Menstrual and reproductive factors and risk of breast cancer: A case-control study in the Fez region, Morocco

BACKGROUND

Breast cancer is the most common cancer in women worldwide. In the Moroccan context, the role of well-known reproductive factors in breast cancer remains poorly documented. The aim of this study was to explore the relationship between menstrual and reproductive factors and breast cancer risk in Moroccan women in the Fez region.

METHODS

A case-control study was conducted at the Hassan II University Hospital of Fez between January 2014 and April 2015. A total of 237 cases of breast cancer and 237 age-matched controls were included. Information on sociodemographic characteristics, menstrual and reproductive history, family history of breast cancer, and lifestyle factors was obtained through a structured questionnaire. Conditional logistic regression models were used to estimate odds ratios and 95% confidence intervals for breast cancer by menstrual and reproductive factors adjusted for potential confounders.

RESULTS

Early menarche (OR = 1.60, 95% CI: 1.08-2.38) and nulliparity (OR = 3.77, 95% CI: 1.98-7.30) were significantly related to an increased risk of breast cancer, whereas an early age at first full-term pregnancy was associated with a decreased risk of breast cancer (OR = 0.41, 95% CI: 0.25-0.65).

CONCLUSION

The results of this study confirm the role of established reproductive factors for breast cancer in Moroccan women. It identified some susceptible groups at high risk of breast cancer. Preventive interventions and screening should focus on these groups as a priority. These results should be confirmed in a larger, multicenter study.

Micronutrient status in middle childhood and age at menarche: results from the Bogotá School Children Cohort

Childhood intake of animal foods is associated with age at first menstrual period (menarche). It is unknown whether the micronutrients present in these foods could explain this association. Our objective was to investigate the associations of micronutrient status biomarkers in middle childhood with age at menarche. We quantified circulating Hb, ferritin, mean corpuscular volume, Zn, vitamin B12, erythrocyte folate and retinol in 1464 pre-menarcheal girls aged 5–12 years in Bogotá, Colombia, and followed them for a median 5·7 years for the occurrence and date of menarche. We estimated median age at menarche and hazard ratios (HR) with 95 % CI by levels of each biomarker with use of Kaplan–Meier survival probabilities and Cox regression, respectively. Median age at menarche was 12·4 years. Middle childhood Hb was inversely related to age at menarche whereas plasma ferritin was positively associated with this outcome in a linear manner. HR of menarche for every 1sdof Hb (11 g/l) and ferritin (23·2 µg/l) were 1·11 (95 % CI 1·04, 1·18;P=0·001) and 0·94 (95 % CI 0·88, 0·99;P=0·02), respectively, after adjustment for baseline age, C-reactive protein concentration, maternal age at menarche and parity and socioeconomic status. The association with ferritin was stronger in girls aged 9–10 years at baseline. Additional adjustment for baseline height- and BMI-for-age did not change the results. We conclude that higher Fe status in middle childhood is related to later age at menarche whereas Hb concentrations are inversely associated with age at onset of menses.

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.

Safety and efficiency of oocyte vitrification

As the oocyte is the starting point for a new life, artificial reproductive technology (ART) techniques should not affect the (ultra) structural and functional integrity, or the developmental competence. Oocyte vitrification -one of the most significant achievements in human ART during the past decade- should therefore be a safe and efficient technique. This review discusses the principles and developments of the existing and future techniques, applications possibilities and safety concerns. The broad range of vitrification media and devices that are currently available, show differences in their effects on the oocyte ultrastructure and preimplantation development. It is not yet fully decided whether this has an influence on the obstetric and neonatal outcome, since only limited information is available with different media and devices. For autologous oocytes, the obstetric and neonatal outcomes appear promising and comparable to pregnancies obtained with fresh oocytes. This however, is not the case for heterologous fresh or vitrified oocytes, where the immunological foreign foetus induces adverse obstetric and neonatal outcomes. Besides the oocyte vitrification process itself, the effect of multiple stimulations (for oocyte banking or for oocyte donors), seems to influence the possibility to develop gynaecological cancers further in life. Automated vitrification/warming should offer a consistent, cross-contamination free process that offers the highest safety level for the users. They should also produce more consistent results in survival, development and clinical pregnancies between different IVF clinics.

Age at menarche and lung function: a Mendelian randomization study

A trend towards earlier menarche in women has been associated with childhood factors (e.g. obesity) and hypothesised environmental exposures (e.g. endocrine disruptors present in household products). Observational evidence has shown detrimental effects of early menarche on various health outcomes including adult lung function, but these might represent spurious associations due to confounding. To address this we used Mendelian randomization where genetic variants are used as proxies for age at menarche, since genetic associations are not affected by classical confounding. We estimated the effects of age at menarche on forced vital capacity (FVC), a proxy for restrictive lung impairment, and ratio of forced expiratory volume in one second to FVC (FEV1/FVC), a measure of airway obstruction, in both adulthood and adolescence. We derived SNP-age at menarche association estimates for 122 variants from a published genome-wide meta-analysis (N = 182,416), with SNP-lung function estimates obtained by meta-analysing three studies of adult women (N = 46,944) and two of adolescent girls (N = 3025). We investigated the impact of departures from the assumption of no pleiotropy through sensitivity analyses. In adult women, in line with previous evidence, we found an effect on restrictive lung impairment with a 24.8 mL increase in FVC per year increase in age at menarche (95% CI 1.8-47.9; p = 0.035); evidence was stronger after excluding potential pleiotropic variants (43.6 mL; 17.2-69.9; p = 0.001). In adolescent girls we found an opposite effect (-56.5 mL; -108.3 to -4.7; p = 0.033), suggesting that the detrimental effect in adulthood may be preceded by a short-term post-pubertal benefit. Our secondary analyses showing results in the same direction in men and boys, in whom age at menarche SNPs have also shown association with sexual development, suggest a role for pubertal timing in general rather than menarche specifically. We found no effect on airway obstruction (FEV1/FVC).

Studying the relationship between a woman's reproductive lifespan and age at menarche using a Bayesian multivariate structured additive distributional regression model

Studies addressing breast cancer risk factors have been looking at trends relative to age at menarche and menopause. These studies point to a downward trend of age at menarche and an upward trend for age at menopause, meaning an increase of a woman's reproductive lifespan cycle. In addition to studying the effect of the year of birth on the expectation of age at menarche and a woman's reproductive lifespan, it is important to understand how a woman's cohort affects the correlation between these two variables. Since the behavior of age at menarche and menopause may vary with the geographic location of a woman's residence, the spatial effect of the municipality where a woman resides needs to be considered. Thus, a Bayesian multivariate structured additive distributional regression model is proposed in order to analyze how a woman's municipality and year of birth affects a woman's age of menarche, her lifespan cycle, and the correlation of the two. The data consists of 212,517 postmenopausal women, born between 1920 and 1965, who attended the breast cancer screening program in the central region of Portugal.

Adult Consequences of Self-Limited Delayed Puberty

Delayed puberty is a common condition defined as the lack of sexual maturation by an age ≥2 SD above the population mean. In the absence of an identified underlying cause, the condition is usually self-limited. Although self-limited delayed puberty is largely believed to be a benign developmental variant with no long-term consequences, several studies have suggested that delayed puberty may in fact have both harmful and protective effects on various adult health outcomes. In particular, height and bone mineral density have been shown to be compromised in some studies of adults with a history of delayed puberty. Delayed puberty may also negatively affect adult psychosocial functioning and educational achievement, and individuals with a history of delayed puberty carry a higher risk for metabolic and cardiovascular disorders. In contrast, a history of delayed puberty appears to be protective for breast and endometrial cancer in women and for testicular cancer in men. Most studies on adult outcomes of self-limited delayed puberty have been in small series with significant variability in outcome measures and study criteria. In this article, we review potential medical and psychosocial issues for adults with a history of self-limited delayed puberty, discuss potential mechanisms underlying these issues, and identify gaps in knowledge and directions for future research.

DNA methylation age is elevated in breast tissue of healthy women

Background

Limited evidence suggests that female breast tissue ages faster than other parts of the body according to an epigenetic biomarker of aging known as the “epigenetic clock.” However, it is unknown whether breast tissue samples from healthy women show a similar accelerated aging effect relative to other tissues, and what could drive this acceleration. The goal of this study is to validate our initial finding of advanced DNA methylation (DNAm) age in breast tissue, by directly comparing it to that of peripheral blood tissue from the same individuals, and to do a preliminary assessment of hormonal factors that could explain the difference.

Methods

We utilized n = 80 breast and 80 matching blood tissue samples collected from 40 healthy female participants of the Susan G. Komen Tissue Bank at the Indiana University Simon Cancer Center who donated these samples at two time points spaced at least a year apart. DNA methylation levels (Illumina 450K platform) were used to estimate the DNAm age.

Results

DNAm age was highly correlated with chronological age in both peripheral blood (r = 0.94, p < 0.0001) and breast tissues (r = 0.86, p < 0.0001). A measure of epigenetic age acceleration (age-adjusted DNAm Age) was substantially increased in breast relative to peripheral blood tissue (p = 1.6 × 10⁻¹¹). The difference between DNAm age of breast and blood decreased with advancing chronologic age (r = −0.53, p = 4.4 × 10⁻⁴).

Conclusions

Our data clearly demonstrate that female breast tissue has a higher epigenetic age than blood collected from the same subject. We also observe that the degree of elevation in breast diminishes with advancing age. Future larger studies will be needed to examine associations between epigenetic age acceleration and cumulative hormone exposure.

Electronic supplementary material

The online version of this article (doi:10.1007/s10549-017-4218-4) contains supplementary material, which is available to authorized users.

Signatures of reproductive events on blood counts and biomarkers of inflammation: Implications for chronic disease risk

Whether inflammation mediates how reproductive events affect chronic-disease risk is unclear. We studied inflammatory biomarkers in the context of reproductive events using National Health and Nutrition Examination Survey (NHANES) data. From 15,986 eligible women from the 1999–2011 data cycles, we accessed information on reproductive events, blood counts, C-reactive protein (CRP), and total homocysteine (tHCY). We calculated blood-count ratios including: platelet-lymphocyte (PLR), lymphocyte-monocyte (LMR), platelet-monocyte (PMR), and neutrophil-monocyte (NMR). Using sampling weights per NHANES guidelines, means for counts, ratios, or biomarkers by reproductive events were compared using linear regression. We performed trend tests and calculated p-values with partial sum of squares F-tests. Higher PLR and lower LMR were associated with nulliparity. In postmenopausal women, lower PMR was associated with early age at first birth and higher NMR with later age at and shorter interval since last birth. Lower PNR and higher neutrophils and tHCY were associated with early natural menopause. In all women, the neutrophil count correlated positively with CRP; but, in premenopausal women, correlated inversely with tHCY. Reproductive events leave residual signatures on blood counts and inflammatory biomarkers that could underlie their links to chronic disease risk.

Childhood body mass index at 5.5 years mediates the effect of prenatal maternal stress on daughters’ age at menarche: Project Ice Storm

Early pubertal timing is known to put women at greater risk for adverse physiological and psychological health outcomes. Of the factors that influence girls’ pubertal timing, stress experienced during childhood has been found to advance age at menarche (AAM). However, it is not known if stress experienced by mothers during or in the months before conception can be similarly associated with earlier pubertal timing. Prenatal maternal stress (PNMS) is associated with metabolic changes, such as increased childhood adiposity and risk of obesity, that have been associated with earlier menarchal age. Using a prospective longitudinal design, the present study tested whether PNMS induced by a natural disaster is either directly associated with earlier AAM, or whether there is an indirect association mediated through increased girls’ body mass index (BMI) during childhood. A total of 31 girls, whose mothers were exposed to the Quebec’s January 1998 ice storm during pregnancy were followed from 6 months to 5 1/2 to 5.5 years of age. Mother’s stress was measured within 6 months of the storm. BMI was measured at 5.5 years, and AAM was assessed through teen’s self-report at 13.5 and 15.5 years of age. Results revealed that greater BMI at 5.5 years mediated the effect of PNMS on decreasing AAM [B=−0.059, 95% confidence intervals (−0.18, −0.0035)]. The present study is the first to demonstrate that maternal experience of stressful conditions during pregnancy reduces AAM in the offspring through its effects on childhood BMI. Future research should consider the impact of AAM on other measures of reproductive ability.

Effects of early menarche on physical and psychosocial health problems in adolescent girls and adult women

The menarcheal age of Korean women has been rapidly decreasing for the last 50 years, and the average menarcheal age of women born in the 1990s is approaching 12.6 years. In addition, interest in early puberty has been increasing recently owing to the rapid increase in precocious puberty. Generally, out of concern for short stature and early menarche, idiopathic central precocious puberty in female adolescents is treated with gonadotropin-releasing hormone analogs. Studies to date have described the association between early menarche and psychosocial problems such as delinquency and risky sexual behavior, as well as physical health problems such as obesity, diabetes, cardiovascular diseases, and breast cancer throughout the lifespan of women. However, the pathophysiological mechanism underlying this association has not been clarified thus far. In this article, we review and discuss the existing literature to describe the current understanding of the effects of early menarche on the physical and psychosocial health of adolescent girls and adult women.

Age-Related Change in Mobility: Perspectives From Life Course Epidemiology and Geroscience

Mobility is the most studied and most relevant physical ability affecting quality of life with strong prognostic value for disability and survival. Natural selection has built the "engine" of mobility with great robustness, redundancy, and functional reserve. Efficient patterns of mobility can be acquired during development even by children affected by severe impairments. Analogously, age-associated impairments in mobility-related physiological systems are compensated and overt limitations of mobility only occur when the severity can no longer be compensated. Mobility loss in older persons usually results from multiple impairments in the central nervous system, muscles, joints, and energetic and sensory physiological systems. Early preclinical changes in these physiological systems that precede mobility loss have been poorly studied. Peak performance, rate of decline, compensatory behaviors, or subclinical deterioration of physiological resources may cumulatively influence both timing of mobility loss and chances of recovery, but their role as risk factors has not been adequately characterized. Understanding the natural history of these early changes and intervening on them would likely be the most effective strategy to reduce the burden of disability in the population. For example, young women with low bone peak mass could be counseled to start strength resistance exercise to reduce their high risk of developing osteoporosis and fracture later in life. Expanding this approach to other physiological domains requires collecting and interpreting data from life course epidemiological studies, establishing normative measures of mobility, physical function, and physical activity, and connecting them with life course trajectories of the mobility-relevant physiological domains.

The readability of online breast cancer risk assessment tools

Numerous breast cancer risk assessment tools that allow users to input personal risk information and obtain a personalized breast cancer risk estimate are available on the Internet. The goal of these tools is to increase screening awareness and identify modifiable health behaviors; however, the utility of this risk information is limited by the readability of the material. We undertook this study to assess the overall readability of breast cancer risk assessment tools and accompanying information, as well as to identify areas of suggested improvement. We searched for breast cancer risk assessment tools, using five search terms, on three search engines. All searches were performed on June 12, 2014. Sites that met inclusion criteria were then assessed for readability using the suitability assessment of materials (SAM) and the SMOG readability formula (July 1, 2014–January 31, 2015). The primary outcomes are the frequency distribution of overall SAM readability category (superior, adequate, or not suitable) and mean SMOG reading grade level. The search returned 42 sites were eligible for assessment, only 9 (21.4 %) of which achieved an overall SAM superior rating, and 27 (64.3 %) were deemed adequate. The average SMOG reading grade level was grade 12.1 (SD 1.6, range 9–15). The readability of breast cancer risk assessment tools and the sites that host them is an important barrier to risk communication. This study demonstrates that most breast cancer risk assessment tools are not accessible to individuals with limited health literacy skills. More importantly, this study identifies potential areas of improvement and has the potential to heighten a physician’s awareness of the Internet resources a patient might navigate in their quest for breast cancer risk information.

A Rat Model to Study the Effects of Diet-Induced Obesity on Radiation-Induced Mammary Carcinogenesis

A detailed understanding of the relationship between radiation-induced breast cancer and obesity is needed for appropriate risk management and to prevent the development of a secondary cancer in patients who have been treated with radiation. Our goal was to develop an animal model to study the relationship by combining two existing Sprague-Dawley rat models of radiation-induced mammary carcinogenesis and diet-induced obesity. Female rats were fed a high-fat diet for 4 weeks and categorized as obesity prone or obesity resistant based on their body weight at 7 weeks of age, at which time the rats were irradiated with 4 Gy. Control rats were fed a standard diet and irradiated at the same time and in the same manner. All rats were maintained on their initial diets and assessed for palpable mammary cancers once a week for the next 30 weeks. The obesity-prone rats were heavier than those in the other groups. The obesity-prone rats were also younger than the other animals at the first detection of mammary carcinomas and their carcinoma weights were greater. A tendency toward higher insulin and leptin blood levels were observed in the obesity-prone rats compared to the other two groups. Blood angiotensin II levels were elevated in the obesity-prone and obesity-resistant rats. Genes related to translation and oxidative phosphorylation were upregulated in the carcinomas of obesity-prone rats. Expression profiles from human breast cancers were used to validate this animal model. As angiotensin is potentially an important factor in obesity-related morbidities and breast cancer, a second set of rats was fed in a similar manner, irradiated and then treated with an angiotensin-receptor blocker, losartan and candesartan. Neither blocker altered mammary carcinogenesis; analyses of losartan-treated animals indicated that expression of renin in the renal cortex and of Agtr1a (angiotensin II receptor, type 1) in cancer tissue was significantly upregulated, suggesting the presence of compensating mechanisms for blocking angiotensin-receptor signaling. Thus, obesity-related elevation of insulin and leptin blood levels and an increase in available energy may facilitate sustained protein synthesis in cancer cells, which is required for rapid cancer development.

Risks of developing breast and colorectal cancer in association with incomes and geographic locations in Texas: a retrospective cohort study

BACKGROUND

No study has been conducted to investigate the spatial pattern and association of socioeconomic status (such as income) with breast and colorectal cancer incidence in Texas, United States. This study aimed to determine whether median household income was associated with the risk of developing breast and colorectal cancer in Texas and to identify higher cancer risks by race/ethnicity and geographic areas.

METHODS

This was a retrospective cohort study with an ecological component in using aggregated measures at the county level. We identified 243,677 women with breast cancer and 155,534 men and women with colorectal cancer residing in 254 counties in Texas in 1995-2011 from the public-use dataset of Texas Cancer Registry. The denominator population and median household income at the county level was obtained from the U.S. Bureau of the Census. Cancer incidence rates were calculated as number of cases per 100,000 persons and age-adjusted using the 2000 US population data. We used the ArcGIS v10.1 (geographic information system software) to identify multiple clustered counties with high and low cancer incidences in Texas.

RESULTS

Age-adjusted breast cancer incidence rate in the highest median income quintile group was 151.51 cases per 100,000 in 2008-2011 as compared to 98.95 cases per 100,000 in the lowest median income quintile group. The risk of colorectal cancer appeared to decrease with increasing median income in racial/ethnic population. Spatial analysis revealed the significant low breast cancer incidence cluster regions located in southwest US-Mexico border counties in Texas.

CONCLUSIONS

This study demonstrated that higher income was associated with an increased risk of breast cancer and a decreased risk of colorectal cancer in Texas. There were geographic variations with cancer incidence clustered in high risk areas in Texas. Future studies may need to explore more factors that might explain income and cancer risk associations and their geographic variations.

Breast cancer risk factors

Breast cancer is the most frequently diagnosed neoplastic disease in women around menopause often leading to a significant reduction of these women's ability to function normally in everyday life. The increased breast cancer incidence observed in epidemiological studies in a group of women actively participating in social and professional life implicates the necessity of conducting multidirectional studies in order to identify risk factors associated with the occurrence of this type of neoplasm. Taking the possibility of influencing the neoplastic transformation process in individuals as a criterion, all the risk factors initiating the process can be divided into two groups. The first group would include inherent factors such as age, sex, race, genetic makeup promoting familial occurrence of the neoplastic disease or the occurrence of benign proliferative lesions of the mammary gland. They all constitute independent parameters and do not undergo simple modification in the course of an individual's life. The second group would include extrinsic factors conditioned by lifestyle, diet or long-term medical intervention such as using oral hormonal contraceptives or hormonal replacement therapy and their influence on the neoplastic process may be modified to a certain degree. Identification of modifiable factors may contribute to development of prevention strategies decreasing breast cancer incidence.

Accelerated reproductive aging in females lacking a novel centromere protein SYCP2L

Menopause results from loss of ovarian function and marks the end of a woman's reproductive life. Alleles of the human SYCP2L locus are associated with age at natural menopause (ANM). SYCP2L is a paralogue of the synaptonemal complex protein SYCP2 and is expressed exclusively in oocytes. Here we report that SYCP2L localizes to centromeres of dictyate stage oocytes, which represent the limited pool of primordial oocytes that are formed perinatally and remain arrested till ovulation. Centromere localization of SYCP2L requires its C-terminal portion, which is missing in truncated variants resulting from low-frequency nonsense mutations identified in humans. Female mice lacking SYCP2L undergo a significantly higher progressive loss of oocytes with age compared with wild-type females and are less fertile. Specifically, the pool of primordial oocytes becomes more rapidly depleted in SYCP2L-deficient than in wild-type females, such that with aging, fewer oocytes undergo maturation in developing follicles. We find that a human SYCP2L intronic single nucleotide polymorphism (SNP) rs2153157, which is associated with ANM, changes the splicing efficiency of U12-type minor introns and may therefore regulate the steady-state amount of SYCP2L transcript. Furthermore, the more efficiently spliced allele of this intronic SNP in SYCP2L is associated with increased ANM. Our results suggest that SYCP2L promotes the survival of primordial oocytes and thus provide functional evidence for its association with ANM in humans.

Milk Consumption after Age 9 Years Does Not Predict Age at Menarche

BACKGROUND

Regular milk consumption during childhood and adolescence is recommended for bone health. However, milk consumption increases circulating insulin-like growth factor I concentrations, and may also accelerate puberty.

OBJECTIVE

We prospectively investigated the association between milk consumption and age at menarche in the Growing Up Today Study.

METHODS

Study participants were 5583 US girls who were premenarcheal and ages 9-14 y in 1996. Girls were followed through 2001, at which time 97% of noncensored participants had reported menarche. Frequency of milk and meat consumption was calculated with the use of annual youth/adolescent food frequency questionnaires from 1996-1998. Intake of related nutrients was also measured. Age at menarche was self-reported annually through 2001.

RESULTS

During follow-up, 5227 girls attained menarche over 10,555 accrued person-years. In models adjusted for dietary and sociodemographic predictors of menarche, frequency of milk consumption did not predict age at onset of menarche (for >3 glasses of milk/d vs. 1.1-4 glasses/wk, HR: 0.93; 95% CI: 0.83, 1.04). After additional adjustment for body size, premenarcheal girls consuming >3 glasses of milk daily were 13% less likely (95% CI: -3%, -23%; P-trend: <0.01) to attain menarche in the next month relative to those consuming 1.1-4 glasses/wk. Neither total meat nor red meat consumption was associated with age at menarche.

CONCLUSIONS

Our findings suggest that regular consumption of milk in girls aged ≥9 y is unlikely to substantially affect age at onset of menarche. Studies assessing associations between diet in early childhood and pubertal timing may be more illuminating.

Secular trends in age at menarche among Chinese girls from 24 ethnic minorities, 1985 to 2010

BACKGROUND

Declining age at menarche has been observed in many countries. In China, a decrease of 4.5 months per decade in the average age at menarche among the majority Han girls has recently been reported. However, the trends in age at menarche among ethnic minority girls over the past 25 years remain unknown.

OBJECTIVES

To compare the differences in median age at menarche among girls aged 9-18 years across 24 ethnic minorities in 2010 and to estimate the trends in age at menarche in different ethnic minorities from 1985 to 2010.

DESIGN

We used data from six cross-sectional Chinese National Surveys on Students' Constitution and Health (1985, 1991, 1995, 2000, 2005, and 2010). The median age at menarche was estimated by using probit analysis.

RESULTS

In 2010, the ethnic minorities with the earliest age at menarche were the Koreans (11.79 years), Mongolians (12.44 years), and Zhuang (12.52 years). The three ethnic minorities with the latest age at menarche were the Sala (14.32 years), Yi (13.74 years), and Uighurs (13.67 years). From 1985 to 2010, the age at menarche declined in all 24 minority groups. The Lisu, Kazakh, and Korean minorities showed the largest reductions in age at menarche by 1.79 (p<0.05), 1.69 (p<0.05), and 1.57 (p<0.05) years, respectively, from 1985 to 2010. The Yi, Sala, and Li minorities showed the smallest reductions, with age at menarche declining by only 0.06 (p>0.05), 0.15 (p>0.05), and 0.15 (p>0.05) years, respectively, in the same period.

CONCLUSION

A large variation in age at menarche was observed among different ethnic minorities, with the earliest age at menarche found among Korean girls. A reduction in the average age at menarche appeared among most of the ethnic minorities over time, and the largest decrease was observed in Lisu, Kazakh, and Korean girls. Thus, health education should focus on targeting the specific needs of each ethnic minority group.

Risk Factors for Premenopausal Breast Cancer in Bangladesh

Background. The incidence of premenopausal breast cancer is rising throughout South Asia. Our objective was to determine the role of risk factors associated with Westernization for premenopausal breast cancer in Bangladesh. Methods. We conducted a matched case-control study between January 1, 2007, and December 31, 2010, at four hospitals in Bangladesh. Cases were premenopausal women diagnosed with invasive breast cancer. Controls were premenopausal women with no personal history of breast cancer. Logistic regression was used to calculate the odds ratios (OR) for breast cancer. Results. We identified 129 age-matched pairs. The mean age of breast cancer diagnosis was 37.5 years. Each year decrease in the age of menarche significantly increased the risk of breast cancer (OR = 1.67, 95% CI 1.09–2.56, P = 0.02). The risk was also increased with a current body mass index of ≥25 kg/m² (OR = 5.24, 95% CI 1.10–24.9, P = 0.04). Age at first childbirth, parity, and breastfeeding were not significantly associated with premenopausal breast cancer risk (P > 0.05). Conclusions. Age at menarche and adult weight gain were associated with premenopausal breast cancer risk. Other factors associated with Westernization may not be relevant to premenopausal breast cancer risk in Bangladesh.

Diets high in corn oil or extra-virgin olive oil differentially modify the gene expression profile of the mammary gland and influence experimental breast cancer susceptibility

PURPOSE

Nutritional factors, especially dietary lipids, may have a role in the etiology of breast cancer. We aimed to analyze the effects of high-fat diets on the susceptibility of the mammary gland to experimental malignant transformation.

METHODS

Female Sprague-Dawley rats were fed a low-fat, high-corn-oil, or high-extra-virgin olive oil (EVOO) diet from weaning or from induction. Animals were induced with 7,12-dimethylbenz[a]anthracene at 53 days and euthanized at 36, 51, 100 and 246 days. Gene expression profiles of mammary glands were determined by microarrays. Further molecular analyses were performed by real-time PCR, TUNEL and immunohistochemistry. Carcinogenesis parameters were determined at 105 and 246 days.

RESULTS

High-corn-oil diet increased body weight and mass when administered from weaning. The EVOO diet did not modify these parameters and increased the hepatic expression of UCP2, suggesting a decrease in intake/expenditure balance. Both diets differentially modified the gene expression profile of the mammary gland, especially after short dietary intervention. Corn oil down-regulated the expression of genes related to immune system and apoptosis, whereas EVOO modified the expression of metabolism genes. Further analysis suggested an increase in proliferation and lower apoptosis in the mammary glands by effect of the high-corn-oil diet, which may be one of the mechanisms of its clear stimulating effect on carcinogenesis.

CONCLUSIONS

The high-corn-oil diet strongly stimulates mammary tumorigenesis in association with modifications in the expression profile and an increased proliferation/apoptosis balance of the mammary gland.

Puberty and perimenopause: reproductive transitions and their implications for women's health

This scoping review synthesizes existing research on two major transitions in females' lives: puberty and perimenopause. These two periods of vast physiological change demarcate the beginning and the end of the reproductive life cycle and are associated with major neuroendocrine reorganization across two key systems, the hypothalamic-pituitary-gonadal (HPG) axis the hypothalamus-pituitary-adrenal (HPA) axis. Despite growing evidence suggesting that the timing and experience of puberty and perimenopause are related to various physical and mental health outcomes (e.g., mood disorders, metabolism, cardiovascular health, autoimmune conditions, and cancer), these two processes are rarely examined together. In this paper, we bridge these disparate literatures to highlight similarities, isolate inconsistencies, and identify important areas for future research in women's health.

Sugar-sweetened beverage consumption and age at menarche in a prospective study of US girls

STUDY QUESTION

Is sugar-sweetened beverage (SSB) consumption associated with age at menarche?

SUMMARY ANSWER

More frequent SSB consumption was associated with earlier menarche in a population of US girls.

WHAT IS KNOWN ALREADY

SSB consumption is associated with metabolic changes that could potentially impact menarcheal timing, but direct associations with age at menarche have yet to be investigated.

STUDY DESIGN, SIZE, DURATION

The Growing up Today Study, a prospective cohort study of 16 875 children of Nurses' Health Study II participants residing in all 50 US states. This analysis followed 5583 girls, aged 9-14 years and premenarcheal at baseline, between 1996 and 2001. During 10 555 person-years of follow-up, 94% (n = 5227) of girls reported their age at menarche, and 3% (n = 159) remained premenarcheal in 2001; 4% (n = 197) of eligible girls were censored, primarily for missing age at menarche.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cumulative updated SSB consumption (composed of non-carbonated fruit drinks, sugar-sweetened soda and iced tea) was calculated using annual Youth/Adolescent Food Frequency Questionnaires from 1996 to 1998. Age at menarche was self-reported annually. The association between SSB consumption and age at menarche was assessed using Cox proportional hazards regression.

MAIN RESULTS AND THE ROLE OF CHANCE

More frequent SSB consumption predicted earlier menarche. At any given age between 9 and 18.5 years, premenarcheal girls who reported consuming >1.5 servings of SSBs per day were, on average, 24% more likely [95% confidence interval (CI): 13, 36%; P-trend: <0.001] to attain menarche in the next month relative to girls consuming ≤2 servings of SSBs weekly, adjusting for potential confounders including height, but not BMI (considered an intermediate). Correspondingly, girls consuming >1.5 SSBs daily had an estimated 2.7-month earlier menarche (95% CI: -4.1, -1.3 months) relative to those consuming ≤2 SSBs weekly. The frequency of non-carbonated fruit drink (P-trend: 0.03) and sugar-sweetened soda (P-trend: 0.001), but not iced tea (P-trend: 0.49), consumption also predicted earlier menarche. The effect of SSB consumption on age at menarche was observed in every tertile of baseline BMI. Diet soda and fruit juice consumption were not associated with age at menarche.

LIMITATIONS, REASONS FOR CAUTION

Although we adjusted for a variety of suspected confounders, residual confounding is possible. We did not measure SSB consumption during early childhood, which may be an important window of exposure.

WIDER IMPLICATIONS OF THE FINDINGS

More frequent SSB consumption may predict earlier menarche through mechanisms other than increased BMI. Our findings provide further support for public health efforts to reduce SSB consumption.

STUDY FUNDING/COMPETING INTERESTS

The Growing up Today Study is supported by grant R03 CA 106238. J.L.C. was supported by the Breast Cancer Research Foundation; Training Grant T32ES007069 in Environmental Epidemiology from the National Institute of Environmental Health Sciences, National Institutes of Health; and Training Grant T32HD060454 in Reproductive, Perinatal and Pediatric Epidemiology from the National Institute of Child Health and Human Development, National Institutes of Health. A.L.F. is supported by the American Cancer Society, Research Scholar Grant in Cancer Control. K.B.M. was supported in part by the National Cancer Institute at the National Institutes of Health (Public Health Service grants R01CA158313 and R03CA170952). There are no conflicts of interest to declare.

An evolutionary medicine approach to understanding factors that contribute to chronic obstructive pulmonary disease

Although many studies have been published on the causes and mechanisms of chronic obstructive pulmonary disease (COPD), the reason for the existence of COPD and the reasons why COPD develops in humans have hardly been studied. Evolutionary medical approaches are required to explain not only the proximate factors, such as the causes and mechanisms of a disease, but the ultimate (evolutionary) factors as well, such as why the disease is present and why the disease develops in humans. According to the concepts of evolutionary medicine, disease susceptibility is acquired as a result of natural selection during the evolutionary process of traits linked to the genes involved in disease susceptibility. In this paper, we discuss the following six reasons why COPD develops in humans based on current evolutionary medical theories: (1) evolutionary constraints; (2) mismatch between environmental changes and evolution; (3) co-evolution with pathogenic microorganisms; (4) life history trade-off; (5) defenses and their costs, and (6) reproductive success at the expense of health. Our perspective pursues evolutionary answers to the fundamental question, 'Why are humans susceptible to this common disease, COPD, despite their long evolutionary history?' We believe that the perspectives offered by evolutionary medicine are essential for researchers to better understand the significance of their work.

Trends of age at menarche and association with body mass index in Chinese school-aged girls, 1985-2010

OBJECTIVES

To estimate the shifts in age at menarche from 1985 to 2010, compare the differences of average age at menarche between urban and rural groups, and determine the association of menarche with body mass index (BMI).

STUDY DESIGN

The data were obtained from 4 cross-sectional Chinese National Surveys on Students' Constitution and Health (1985, 1995, 2005, and 2010). In this representative sample of Chinese school-aged girls, the average age at menarche was determined using probit analysis and compared between urban and rural areas. Logistic regression was used to assess the association of BMI with the likelihood of having reached menarche.

RESULTS

The age at menarche in Chinese girls dropped from 13.41 years to 12.47 years from 1985 to 2010. There was a significant difference in age at menarche between urban and rural girls over time, with urban girls having their menarche earlier than rural girls. Logistic regression showed that a higher BMI was strongly associated with an increased likelihood of having reached menarche, even after controlling for age, urban or rural residence, province, social economic status, and school.

CONCLUSION

The analysis suggests a drop of about 4.5 months per decade in the average age at menarche over the past 25 years, and a significant inverse association between BMI and having reached menarche. Considering that both early menarche and higher BMI are significant risk factors for chronic diseases, and may act together in later years to the detriment of a woman's health, greater attention should be paid to the health of girls with earlier menarche and higher BMI.

Prevalence, trends, and determinants of menopause in India: NFHS 1992-93 to NFHS 2005-06

OBJECTIVES

The purpose of this study was to estimate the prevalence of menopause in three rounds of the National Family Health Survey (NFHS), determine correlates of menopause, and estimate the age of start of menopause in Indian women.

METHODS

Three rounds of NFHS data collected during 1992-93, 1998-99, and 2005-06 were analyzed. The NFHS was carried out using a uniform sample design all over the country. Age adjusted complex sample analyses, multivariate logistic regression, and probit analysis were carried out.

RESULTS

The prevalence of menopause (natural and surgical) remained similar from 1992-93 to 2005-06 among Indian women. A higher prevalence and earlier onset of menopause was associated with farming, no education, belonging to a scheduled caste or scheduled tribe, underweight, higher parity, and motherhood before 16 years of age. The age of the start of menopause did not increase much from the first to third round of NFHS.

CONCLUSIONS

Women of poor socio-economic status have an earlier age at menopause and may be unable to utilize their full reproductive potential.

Pathogenesis, prevention, diagnosis and treatment of breast cancer

Breast cancer is the most common cancer affecting women worldwide. Prediction models stratify a woman's risk for developing cancer and can guide screening recommendations based on the presence of known and quantifiable hormonal, environmental, personal, or genetic risk factors. Mammography remains the mainstay breast cancer screening and detection but magnetic resonance imaging and ultrasound have become useful diagnostic adjuncts in select patient populations. The management of breast cancer has seen much refinement with increased specialization and collaboration with multidisciplinary teams that include surgeons, oncologists, radiation oncologists, nurses, geneticist, reconstructive surgeons and patients. Evidence supports a less invasive surgical approach to the staging and management of the axilla in select patients. In the era of patient/tumor specific management, the advent of molecular and genomic profiling is a paradigm shift in the treatment of a biologically heterogenous disease.

Breast cancer and circadian disruption from electric lighting in the modern world

Breast cancer is the leading cause of cancer death among women worldwide, and there is only a limited explanation of why. Risk is highest in the most industrialized countries but also is rising rapidly in the developing world. Known risk factors account for only a portion of the incidence in the high-risk populations, and there has been considerable speculation and many false leads on other possibly major determinants of risk, such as dietary fat. A hallmark of industrialization is the increasing use of electricity to light the night, both within the home and without. It has only recently become clear that this evolutionarily new and, thereby, unnatural exposure can disrupt human circadian rhythmicity, of which three salient features are melatonin production, sleep, and the circadian clock. A convergence of research in cells, rodents, and humans suggests that the health consequences of circadian disruption may be substantial. An innovative experimental model has shown that light at night markedly increases the growth of human breast cancer xenografts in rats. In humans, the theory that light exposure at night increases breast cancer risk leads to specific predictions that are being tested epidemiologically: evidence has accumulated on risk in shift workers, risk in blind women, and the impact of sleep duration on risk. If electric light at night does explain a portion of the breast cancer burden, then there are practical interventions that can be implemented, including more selective use of light and the adoption of recent advances in lighting technology and application.

Bilateral symmetry of breast tissue composition by magnetic resonance in young women and adults

BACKGROUND

Some reports suggest that there is a slightly higher frequency of breast cancer in the left breast compared with the right in middle-aged women. The reasons for this association are unknown. The water and fat content of both breasts was compared using magnetic resonance (MR). Breast water by MR reflects fibro-glandular tissue and is strongly positively correlated with percent mammographic density, a strong risk factor for breast cancer.

METHODS

Magnetic resonance was used to measure fat and water content of the breast in 400 young women aged 15-30 years and a random sample of 100 of their mothers. All MR examinations were carried out using a 1.5T MR system, and 45 contiguous slices were obtained in the sagittal plane. One reader identified the breast tissue in the image, and subsequently, fat and water content was calculated using a three-point Dixon technique. Left- and right-sided images were read independently in random order.

RESULTS

In young women, mean percent water was on average 0.84 % higher in the right compared with the left breast (p < 0.001) and total breast water was on average 6.42 cm(3) greater on the right side (p < 0.001). In mothers, there were no significant differences in any breast measure between right and left sides.

CONCLUSION

The small differences in breast tissue composition in young women are unlikely to be associated with large differences in breast cancer risk between sides. The reported excess of left-sided breast cancer in older women is unlikely to be explained by differences in breast tissue composition.

Structured additive regression modeling of age of menarche and menopause in a breast cancer screening program

Breast cancer risk is believed to be associated with several reproductive factors, such as early menarche and late menopause. This study is based on the registries of the first time a woman enters the screening program, and presents a spatio-temporal analysis of the variables age of menarche and age of menopause along with other reproductive and socioeconomic factors. The database was provided by the Portuguese Cancer League (LPCC), a private nonprofit organization dealing with multiple issues related to oncology of which the Breast Cancer Screening Program is one of its main activities. The registry consists of 259,652 records of women who entered the screening program for the first time between 1990 and 2007 (45-69-year age group). Structured Additive Regression (STAR) models were used to explore spatial and temporal correlations with a wide range of covariates. These models are flexible enough to deal with a variety of complex datasets, allowing us to reveal possible relationships among the variables considered in this study. The analysis shows that early menarche occurs in younger women and in municipalities located in the interior of central Portugal. Women living in inland municipalities register later ages for menopause, and those born in central Portugal after 1933 show a decreasing trend in the age of menopause. Younger ages of menarche and late menopause are observed in municipalities with a higher purchasing power index. The analysis performed in this study portrays the time evolution of the age of menarche and age of menopause and their spatial characterization, adding to the identification of factors that could be of the utmost importance in future breast cancer incidence research.

Timing of pubertal stages and breast cancer risk: the Breakthrough Generations Study

INTRODUCTION

Breast development and hormonal changes at puberty might affect breast cancer risk, but epidemiological analyses have focussed largely on age at menarche and not at other pubertal stages.

METHODS

We investigated associations between the timing of pubertal stages and breast cancer risk using data from a cohort study of 104,931 women (Breakthrough Generations Study, UK, 2003-2013). Pubertal variables were reported retrospectively at baseline. Breast cancer risk was analysed using Cox regression models with breast cancer diagnosis as the outcome of interest, attained age as the underlying time variable, and adjustment for potentially confounding variables.

RESULTS

During follow-up (mean = 4.1 years), 1094 breast cancers (including ductal carcinoma in situ) occurred. An increased breast cancer risk was associated with earlier thelarche (age when breast growth begins; HR [95% CI] = 1.23 [1.02, 1.48], 1 [referent] and 0.80 [0.69, 0.93] for ≤10, 11-12 and ≥13 years respectively), menarche (initiation of menses; 1.06 [0.93, 1.21], 1 [referent] and 0.78 [0.62, 0.99] for ≤12, 13-14 and ≥15 years), regular periods (0.99 [0.83, 1.18], 1 [referent] and 0.74 [0.59, 0.92] for ≤12, 13-14 and ≥15 years) and age reached adult height (1.25 [1.03, 1.52], 1 [referent] and 1.07 [0.87, 1.32] for ≤14, 15-16 and ≥17 years), and with increased time between thelarche and menarche (0.87 [0.65, 1.15], 1 [referent], 1.14 [0.96, 1.34] and 1.27 [1.04, 1.55] for <0, 0, 1 and ≥2 years), and shorter time between menarche and regular periods (1 [referent], 0.87 [0.73, 1.04] and 0.66 [0.50, 0.88] for 0, 1 and ≥2 years). These associations were generally similar when considered separately for premenopausal and postmenopausal breast cancer.

CONCLUSIONS

Breast duct development may be a time of heightened susceptibility to risk of carcinogenesis, and greater attention needs to be given to the relation of breast cancer risk to the different stages of puberty.

Suitable trial designs and cohorts for preventive breast cancer agents

Effective chemoprevention of oestrogen receptor (ER)-positive breast cancer has been shown convincingly using several selective ER modulators and the aromatase inhibitor exemestane. Although these agents are well tolerated and the numbers needed-to-treat in the prevention setting are similar to other established preventive interventions, uptake has been poor in clinical practice because of difficulties in visualizing risk, predicting individual outcomes and measuring treatment benefit. In addition, new agents targeting ER-negative breast cancer are urgently needed. The development of new agents is hampered by the lack of suitable biomarkers and targets, as well as regulatory and financial considerations. Establishing breast cancer chemoprevention in standard clinical practice will require advances in many different fields, including biomarker research, the development of more powerful tools to predict and communicate the risks and benefits of treatments and establishing innovative trial designs. Furthermore, changes in regulatory procedures could reduce the size and cost of trials needed in the prevention setting. Identification of biomarkers for risk and efficacy that are easily accessible, such as blood-based biomarkers, will be key to future chemoprevention strategies.

Relationships between age of puberty onset and height at age 18 years in girls and boys

BACKGROUND

Changes during puberty may influence final adult height. Height is related to multiple health conditions, including lung function. We investigated the association between the age of onset of five puberty events and height at age 18 years, analyzing boys and girls separately.

METHODS

Of 1456 children recruited into the Isle of Wight birth cohort (1989-1990), 1313 were followed up at age 18 years. Height was measured, and age of pubertal onset was collected at age 18 years. Cluster analysis was performed on the five puberty events in boys and girls and linear regression was applied with the clusters predicting height at age 18 years. Individual linear regression analyses assessed the age of onset of each pubertal event as a potential predictor for height at age 18 years.

RESULTS

Of the 1313 children followed up at age 18 years, 653 were males and 660 were females. All puberty variables had high internal consistency. In girls, earlier age of menarche, breast development, and growth spurt were related to shorter height. In boys, earlier age of growth spurt and slower progression through puberty were related to taller height at age 18 years.

CONCLUSIONS

Given that boys and girls may have opposing associations between pubertal timing and adult height and that height is an important predictor of lung function, the effect of pubertal timing on respiratory health should be explored.

A model for breast cancer risk based on stem-cell theory

Recent studies of cells in culture and of mice models support the notion that the mammary stem cell is a precursor to the breast cancer cell 1–4. [...]

Age-specific effect of gender on upper tract urothelial carcinoma outcomes

The research is to evaluate the age-specific differential effects of gender on outcomes in patients with upper tract urothelial carcinoma (UTUC) treated with radical nephroureterectomy (RNU). Between August 1998 and October 2010, we retrospectively reviewed the data from 285 (67.7%) men and 136 (32.3%) women treated with RNU for UTUC at our two institutions. Kaplan-Meier survival estimates the age-specific effect of gender on cancer-specific survival (CSS). Cox proportional hazards regression analyses were used to address the effect of gender on CSS. No significant sex-related differences were found in age and diagnosis, clinicopathologic features, and treatment (all P values >0.05). Women had a 18.7% increased risk of death from UTUC than men (hazard ratio [HR] 1.187; 95% confidence interval [95% CI] 1.017-1.893; P = 0.021). The survival disadvantage was only present in patients aged 59 years and older (P < 0.001). Conversely, the survival advantage for women was found in women aged 42 to 58 years (P = 0.011) and in the age group <42 years (P = 0.019). On multivariable Cox regression analyses that adjusted for the effects of clinicopathologic features, the female gender was associated with decreased CSS (P = 0.036). In conclusion, the impact of gender on UTUC outcomes after RNU is age-specific. Females who aged 59 years and older experienced worse outcomes than their male counterparts, while women in the age group <42 years and 42-58 years have better outcomes than men. Further research is needed to elucidate the molecular mechanisms underlying the age-specific differential effect of gender on UTUC outcomes.

Influence of ABO blood group and Rhesus factor on breast cancer risk: a meta-analysis of 9665 breast cancer patients and 244,768 controls

AIM

Blood group is an important risk factor for some malignancies, including pancreatic and stomach cancer. However, it is unclear whether the risk of breast cancer is higher in any specific ABO blood type.

METHODS

We searched the electronic database of PubMed, EMBASE, China National Knowledge Infrastructure and the VIP Chinese Journal of Science and Technology for case-control studies about blood type and breast cancer incidence, and a meta-analysis was conducted.

RESULTS

Fourteen studies were eligible for assessment on the association of breast cancer with different blood types, including 9665 breast cancer patients and 244,768 controls. Relative to blood type O, women with blood type A (odds ratio (OR) = 1.115, 95% confidence interval (CI) 0.992-1.254), B (OR = 0.983, 95% CI 0.915-1.056) and AB (OR = 1.042, 95% CI 0.881-1.231) had the same breast cancer risk. The risk for women with Rhesus-positive (Rh+) was the same as those with Rh-negative (Rh-) (OR = 0.948, 95% CI 0.667-1.348). Among Caucasians, the OR of blood type A was 1.066 (95% CI, 1.001-1.134, P = 0.522 for heterogeneity).

CONCLUSION

This meta-analysis suggests Caucasians with blood type A may have a higher risk of breast cancer than other Caucasians. No association was found in any other blood type or any other population. Similarly, the Rh factor had no association with the risk of breast cancer.

Age at natural menopause in relation to all-cause and cause-specific mortality in a follow-up study of US black women

OBJECTIVES

Early age at natural menopause has been associated with increased all-cause mortality in several studies, although the literature is not consistent. This relation has not been examined among African American women.

STUDY DESIGN

Data were from the Black Women's Health Study, a follow-up study of African-American women enrolled in 1995. Among 11,212 women who were naturally menopausal at entry to the study or during follow-up through 2008, we assessed the relation of age at natural menopause to all-cause and cause-specific mortality. At baseline and biennially, participants reported on reproductive and medical history, including gynecologic surgeries and exogenous hormone use. Mortality data were obtained from the National Death Index. Multivariable Cox proportional hazard models were used to estimate mortality rate ratios (MRR) and 95% confidence intervals (CI) for categories of age at menopause.

RESULTS

Of 692 deaths identified during 91,829 person years of follow-up, 261 were due to cancer, 199 to cardiovascular diseases and 232 to other causes. Natural menopause before age 40 was associated with increased all-cause mortality (MRR=1.34, 95% CI 0.96-1.84, relative to menopause at 50-54 years; P-trend=0.04) and with the subcategories of death considered - cancer, cardiovascular disease, and all other causes. The associations were present among never and ever users of postmenopausal female hormones and among never and ever smokers.

CONCLUSIONS

In this large prospective cohort of African-American women, natural menopause before age 40 was associated with a higher rate of all-cause and cause-specific mortality. These findings provide support for the theory that natural menopause before age 40 may be a marker of accelerated somatic aging.

Replication of genetic loci for ages at menarche and menopause in the multi-ethnic Population Architecture using Genomics and Epidemiology (PAGE) study

STUDY QUESTION

Do genetic associations identified in genome-wide association studies (GWAS) of age at menarche (AM) and age at natural menopause (ANM) replicate in women of diverse race/ancestry from the Population Architecture using Genomics and Epidemiology (PAGE) Study?

SUMMARY ANSWER

We replicated GWAS reproductive trait single nucleotide polymorphisms (SNPs) in our European descent population and found that many SNPs were also associated with AM and ANM in populations of diverse ancestry.

WHAT IS KNOWN ALREADY

Menarche and menopause mark the reproductive lifespan in women and are important risk factors for chronic diseases including obesity, cardiovascular disease and cancer. Both events are believed to be influenced by environmental and genetic factors, and vary in populations differing by genetic ancestry and geography. Most genetic variants associated with these traits have been identified in GWAS of European-descent populations.

STUDY DESIGN, SIZE, DURATION

A total of 42 251 women of diverse ancestry from PAGE were included in cross-sectional analyses of AM and ANM.

MATERIALS, SETTING, METHODS

SNPs previously associated with ANM (n = 5 SNPs) and AM (n = 3 SNPs) in GWAS were genotyped in American Indians, African Americans, Asians, European Americans, Hispanics and Native Hawaiians. To test SNP associations with ANM or AM, we used linear regression models stratified by race/ethnicity and PAGE sub-study. Results were then combined in race-specific fixed effect meta-analyses for each outcome. For replication and generalization analyses, significance was defined at P < 0.01 for ANM analyses and P < 0.017 for AM analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

We replicated findings for AM SNPs in the LIN28B locus and an intergenic region on 9q31 in European Americans. The LIN28B SNPs (rs314277 and rs314280) were also significantly associated with AM in Asians, but not in other race/ethnicity groups. Linkage disequilibrium (LD) patterns at this locus varied widely among the ancestral groups. With the exception of an intergenic SNP at 13q34, all ANM SNPs replicated in European Americans. Three were significantly associated with ANM in other race/ethnicity populations: rs2153157 (6p24.2/SYCP2L), rs365132 (5q35/UIMC1) and rs16991615 (20p12.3/MCM8). While rs1172822 (19q13/BRSK1) was not significant in the populations of non-European descent, effect sizes showed similar trends.

LIMITATIONS, REASONS FOR CAUTION

Lack of association for the GWAS SNPs in the non-European American groups may be due to differences in locus LD patterns between these groups and the European-descent populations included in the GWAS discovery studies; and in some cases, lower power may also contribute to non-significant findings.

WIDER IMPLICATIONS OF THE FINDINGS

The discovery of genetic variants associated with the reproductive traits provides an important opportunity to elucidate the biological mechanisms involved with normal variation and disorders of menarche and menopause. In this study we replicated most, but not all reported SNPs in European descent populations and examined the epidemiologic architecture of these early reported variants, describing their generalizability and effect size across differing ancestral populations. Such data will be increasingly important for prioritizing GWAS SNPs for follow-up in fine-mapping and resequencing studies, as well as in translational research.