Associations of body size and reproductive factors with circulating levels of sex hormones and prolactin in premenopausal Japanese women

Hormone-associated dietary patterns and premenopausal breast cancer risk

PURPOSE

Circulating levels of sex steroid hormones have previously been associated with premenopausal breast cancer risk. Few studies have considered the association between dietary patterns and premenopausal hormone levels. Our objective was to derive dietary patterns associated with premenopausal hormone levels and investigate the association between pattern scores and premenopausal breast cancer risk.

METHODS

Using reduced rank regression among a subset of participants from the Nurses' Health Study II (NHSII) (n = 8,962), we identified dietary patterns correlated with premenopausal levels of five sex steroid hormones measured in the follicular and luteal phases. Then, in the full NHSII cohort (n = 90,341), we used Cox proportional hazards models to calculate hazard ratios (HRs) for breast cancer risk associated with each dietary pattern score.

RESULTS

Dietary patterns were identified for luteal estradiol, luteal free estradiol, follicular estrone, luteal estrone, and free testosterone. However, these patterns explained a low percent variation in individual hormone levels, ranging from 2.5-4.1%. During 24 years of follow-up, 1,956 premenopausal breast cancer cases were ascertained. Dietary patterns associated with luteal free estradiol (HR for fifth versus first quintile = 1.29; 95% CI = 1.11-1.49; Ptrend < 0.01) and follicular estrone (HR for fifth versus first quintile = 1.28; 95% CI = 1.10-1.49; Ptrend < 0.01) were positively associated with premenopausal breast cancer risk.

CONCLUSION

Our findings indicate that while some dietary factors may marginally influence premenopausal hormone levels, the relation between sex steroid hormones and premenopausal breast cancer risk is likely not driven by diet. Future studies should consider other mechanisms through which diet may impact breast cancer risk, including inflammatory processes.

Testosterone mediates life-history trade-offs in female mammals

Hormones mediate life-history trade-offs. In female mammals, such trade-offs have been studied predominantly in the contexts of oestrogen, progesterone and prolactin. We evaluate the hypothesis that prenatal and postnatal testosterone levels structure and regulate trade-offs in females involving components of reproduction and survival. This hypothesis is predicated on the observation that testosterone confers competition-related and survival-related benefits, but also reproduction-related costs, to female mammals. The hypothesis is supported by field and laboratory data from diverse non-human animals, and data from healthy women. Most broadly, relatively low testosterone level in females has been associated with earlier, faster and higher offspring production, greater attractiveness to males, and reduced dominance or competitiveness, whereas higher testosterone level is associated with delayed and reduced reproduction but increased dominance, status, aggression, and resource accrual. The magnitude of testosterone-mediated trade-offs is expected to depend upon the strength of female-female competition, which represents some function of species-specific ecology, behaviour and mating system. Testosterone-associated trade-offs have, until now, been virtually ignored in studies of female life history, reproductive physiology, evolutionary endocrinology, and female-limited disease, probably due to researcher biases towards conceptualizing androgens as hormones with effects mainly restricted to males.

Menstrual and reproductive factors associated with risk of breast cancer among Indian women: a cross sectional study from National Family Health Survey, 2019-21

BACKGROUND

The breast cancer is common cancer in women globally. The risk of breast cancer is strongly associated with women's menstrual and reproductive factors that have been established in different countries. Therefore present study was aim to explore the association between menstrual and reproductive factors and the risk of breast cancer screening in Indian women.

METHODS

The present study data has been used fifth round of the National Family Health Survey (NFHS-V) with 724,115 women in aged 15-49 in 2019-21. The self-reported ever screened of breast cancer for women aged 30-49 was the main outcome variable of the study. 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

Late menarche (OR = 2.20, 95% CI: 1.48-3.28), irregular menstrual cycle (OR = 1.29, 95% CI: 1.08-3.53)), delay age at first birth (OR = 1.93, 95% CI: 1.11-3.04) and contraceptive pill used (OR = 1.11, 95% CI: 0.74-2.10) were significantly associated to increases the uptake of screening breast cancer. While, a higher number of birth (OR = 0.52, 95% CI: 0.10-1.03), and long duration of breast-feeding practice (OR = 0.75, 95% CI: 0.63-0.91) were reduced to participate for screening breast cancer.

CONCLUSION

The results of the study confirm the role of menstrual and reproductive factors in breast cancer in Indian women. Therefore, our findings are imperative for developing breast cancer prevention strategies and better preparedness. Creating awareness and providing knowledge on cancer could be key strategies for the reduction of breast cancer in Indian reproductive age group women.

Sleep-related factors and circulating levels of sex hormones in premenopausal Japanese women

Sleep disruption and circadian disruption have been proposed to be risk factors of breast cancer. The present study examined the associations of sleep-related factors, referring to night shift work, sleep habits, and sleep disturbances, with the plasma levels of sex hormones in premenopausal Japanese women. Study participants were 432 women who had regular menstrual cycles less than 40 days long. Information on their history of night shift work and sleep disturbances was obtained using a self-administered questionnaire. Information on their sleep habits, such as usual wake-up times, bedtimes, and ambient light level while sleeping, was obtained in an interview. The participants' height and weight were measured. Plasma concentrations of estradiol, testosterone, dehydroepiandrosterone sulfate, sex hormone-binding globulin (SHBG), FSH, and LH were also measured. After controlling for the phase of the menstrual cycle and other covariates, more years of night shift work ≥ once a week during the past 10 years was significantly associated with a lower SHBG and a higher free estradiol level. Shorter sleep duration was significantly associated with the higher total, bioavailable, and free testosterone levels. Sleep disturbance by awaking after sleep onset was significantly associated with a high free estradiol level. The data suggest that long-term night shift work, short sleep duration, and arousal during sleep are associated with higher estradiol or testosterone levels in premenopausal women.

Reproductive Factors, Use of Exogenous Hormones, and Pancreatic Cancer Incidence: The Norwegian Women and Cancer Study

Introduction

The incidence of pancreatic cancer is increasing worldwide and characterized by a particularly low survival rate. Studies have reported weak and inconsistent evidence for associations among reproductive factors, use of exogenous hormones, and pancreatic cancer incidence in women.

Purpose

To investigate relationships between reproductive factors, exogenous hormones, and the rate of pancreatic cancer incidence in a large population-based prospective cohort of women in Norway.

Methods

We used data from the Norwegian Women and Cancer study on 588 incident cases of pancreatic cancer diagnosed among 165,419 women, with mean follow-up of 18.7 years. Cox proportional-hazard models were used to estimate HRs and 95% CIs for associations of interest.

Results

Cumulative breastfeeding duration >24 months was associated with 63% decreased incidence of pancreatic cancer compared to no breastfeeding. We observed an inverse linear dose–response trend between cumulative breastfeeding duration and pancreatic cancer incidence, which was confirmed in parous women and ever-smokers. Higher age at first birth and menopause were inversely associated with pancreatic cancer incidence, though with less precise effect estimates. Current use of oral contraceptives was associated with a doubling of pancreatic cancer incidence, but the analysis was hampered by a small number of cases. There was no evidence of any associations between age at menarche, parity or use of menopausal hormone therapy, and incidence of pancreatic cancer.

Conclusion

Our results suggest a potential protective effect of breastfeeding duration against pancreatic cancer incidence. Inconsistent results for the other reproductive factors suggested no important role of estrogens in pancreatic cancer etiology.

Body size and composition, physical activity and sedentary time in relation to endogenous hormones in premenopausal and postmenopausal women: Findings from the UK Biobank

Anthropometric and lifestyle factors may influence cancer risks through hormonal changes. We investigated cross-sectional associations between body size and composition, physical activity and sedentary time and serum concentrations of oestradiol (premenopausal women only), testosterone, sex hormone binding globulin (SHBG) and insulin-like growth factor-I (IGF-I) in 20 758 premenopausal and 71 101 postmenopausal women in UK Biobank. In premenopausal women, higher BMI (body mass index) was associated with a lower concentration of total oestradiol (15% difference in the highest vs lowest BMI group) and a higher concentration of calculated free oestradiol (22%). In both premenopausal and postmenopausal women, higher BMI was associated with higher concentrations of total and calculated free testosterone (premenopausal 29% and 113%, postmenopausal 39% and 126%, respectively) and lower concentrations of SHBG and IGF-I (premenopausal 51% and 14%, postmenopausal 51% and 12%, respectively). Similar associations were observed with waist to height ratio, waist to hip ratio and body or trunk fat mass. Self-reported physical activity was associated with somewhat lower concentrations of total and calculated free testosterone (premenopausal 10% difference [free testosterone], postmenopausal 5% and 11% difference respectively in the most vs least active group) and a higher concentration of SHBG (premenopausal 11%, postmenopausal 10%), and the opposite was true for self-reported sedentary time. The associations were slightly stronger with accelerometer-measured physical activity, but were attenuated after adjustment for BMI. Overall, our study confirms strong associations of hormones and SHBG with anthropometric factors. The associations with physical activity and sedentary time were at most modest.

Association of abdominal fat with metabolic syndrome components in overweight women: effect of menopausal status

BACKGROUND

The association between abdominal fat distribution and metabolic syndrome (MetSyn) components by menopausal status has yet to be explicated. The purpose of this study was to examine a cross-sectional association between abdominal fat compartments and MetSyn components in pre- and post-menopausal overweight Japanese women.

METHODS

Of 212 overweight Japanese women, 76 pre-menopausal overweight (BMI ≥ 25) women (PreM age, 42.1 ± 5.9 years) and 87 post-menopausal overweight women (PostM: age, 56.2 ± 4.5 years) were analyzed in this study. Measurements were taken for body mass index (BMI), abdominal compartments [visceral fat (VF), subcutaneous fat (SF), superficial subcutaneous fat (SSF), and deep subcutaneous fat (DSF)], serum high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol, triglycerides (TG), and fasting plasma glucose (FPG). Abdominal compartments were assessed using computed tomography.

RESULTS

No significant differences were found for BMI, SF, SSF, or DSF between the PreM and PostM. Despite this, the PreM had a significantly smaller VF area than that of the PostM. However, the difference in VF area disappeared when age was adjusted for. VFA significantly correlated with HDLC, TG, and FPG independently of menopause status.

CONCLUSIONS

These results suggest that the effect of menopause status on the association between VF and MetSyn components is negligible. Abdominal subcutaneous fat compartments were not associated with MetSyn components in overweight women regardless of menopausal status.

Circulating steroid levels as correlates of adipose tissue phenotype in premenopausal women

Background Obesity-related alterations in the circulating steroid hormone profile remain equivocal in women. Our objective was to identify circulating steroid levels that relate to increased adiposity and altered adipose phenotype in premenopausal women. Materials and methods In a sample of 42 premenopausal women [age 46 ± 3 years; body mass index (BMI) 27.1 ± 4.2 kg/m2], 19 plasma steroids were quantified by electrospray ionization-liquid chromatography-tandem mass spectroscopy (ESI-LC-MS/MS). Body composition and fat distribution were assessed by dual-energy X-ray absorptiometry (DXA) and computed tomography (CT), respectively. Markers of adipose tissue function including adipocyte size distributions, radiological attenuation and macrophage infiltration were also analyzed in surgically obtained visceral and subcutaneous fat samples. Results Many negative correlations were observed between adiposity measurements such as BMI, body fat percentage or total abdominal adipose tissue area and plasma levels of androstenedione (Δ4) (r = -0.33 to -0.39, p ≤ 0.04), androsterone (ADT) (r = -0.30 to -0.38, p ≤ 0.05) and steroid precursor pregnenolone (PREG) (r = -0.36 to -0.46, p ≤ 0.02). Visceral adipocyte hypertrophy was observed in patients with low PREG concentrations (p < 0.05). Visceral adipose tissue radiologic attenuation, a potential marker of adipocyte size, was also positively correlated with PREG levels (r = 0.33, p < 0.05). Low levels of PREG were related to increased number of macrophages infiltrating visceral and subcutaneous adipose tissue (p < 0.05). Conclusion Plasma levels of androgens and their precursors are lower in women with increased adiposity and visceral adipocyte hypertrophy. Low circulating PREG concentration may represent a marker of adipose tissue dysfunction.

Determinants of prolactin in postmenopausal Chinese women in Singapore

PURPOSE

Mechanistic and observational data together support a role for prolactin in breast cancer development. Determinants of prolactin in Asian populations have not been meaningfully explored, despite the lower risk of breast cancer in Asian populations.

METHODS

Determinants of plasma prolactin were evaluated in 442 postmenopausal women enrolled in the Singapore Chinese Health Study, a population-based prospective cohort study. At baseline all cohort members completed an in-person interview that elicited information on diet, menstrual and reproductive history, and lifestyle factors. One year after cohort initiation we began collecting blood samples. Quantified were plasma concentrations of prolactin, estrone, estradiol, testosterone, androstenedione, and sex hormone-binding globulin (SHBG). Analysis of covariance method was used for statistical analyses with age at blood draw, time since last meal, and time at blood draw as covariates.

RESULTS

Mean prolactin levels were 25.1% lower with older age at menarche (p value = 0.001), and 27.6% higher with greater years between menarche and menopause (p value = 0.009). Prolactin levels were also positively associated with increased sleep duration (p value = 0.005). The independent determinants of prolactin were years from menarche to menopause, hours of sleep, and the plasma hormones estrone and SHBG (all p values < 0.01).

CONCLUSION

The role of prolactin in breast cancer development may involve reproductive and lifestyle factors, such as a longer duration of menstrual cycling and sleep patterns.

Associations of Breast Cancer Risk Factors with Premenopausal Sex Hormones in Women with Very Low Breast Cancer Risk

Breast cancer incidence rates are low but rising in urban Mongolia. We collected reproductive and lifestyle factor information and measured anthropometrics and serum sex steroid concentrations among 314 premenopausal women living in Ulaanbaatar, Mongolia. Mean differences in hormone concentrations by these factors were calculated using age-adjusted quadratic regression splines. Estrone and estradiol in college-educated women were, respectively, 18.2% (p = 0.03) and 23.6% (p = 0.03) lower than in high-school-educated women. Progesterone concentrations appeared 55.8% lower (p = 0.10) in women residing in modern housing compared with women living in traditional housing (gers), although this finding was not statistically significant. Testosterone concentrations were positively associated with adiposity and central fat distribution; 17.1% difference (p = 0.001) for highest vs. lowest quarter for body mass index and 15.1% difference (p = 0.005) for waist-to-height ratio. Estrogens were higher in the follicular phase of women who breastfed each child for shorter durations. A distinct hormonal profile was associated with an urban lifestyle in premenopausal, Mongol women. In particular, heavier, more-educated women living in urban dwellings had higher testosterone and lower estrogen and progesterone levels. Higher breast cancer incidence in urban compared with rural women suggest that the hormonal profile associated with a more traditional lifestyle may be protective among Mongol women.

Long and irregular menstrual cycles, polycystic ovary syndrome, and ovarian cancer risk in a population-based case-control study

Long and irregular menstrual cycles, a hallmark of polycystic ovary syndrome (PCOS), have been associated with higher androgen and lower sex hormone binding globulin levels and this altered hormonal environment may increase the risk of specific histologic subtypes of ovarian cancer. We investigated whether menstrual cycle characteristics and self-reported PCOS were associated with ovarian cancer risk among 2,041 women with epithelial ovarian cancer and 2,100 controls in the New England Case-Control Study (1992-2008). Menstrual cycle irregularity, menstrual cycle length, and PCOS were collected through in-person interview. Unconditional logistic regression models were used to calculate odds ratios (OR) and 95% confidence intervals (95% CIs) for ovarian cancer risk overall, and polytomous logistic regression to evaluate whether risk differed between histologic subtypes. Overall, we observed no elevation in ovarian cancer risk for women who reported periods that were never regular or for those reporting a menstrual cycle length of >35 days with ORs of 0.87 (95% CI = 0.69-1.10) and 0.83 (95% CI = 0.44-1.54), respectively. We observed no overall association between self-reported PCOS and ovarian cancer (OR = 0.97; 95% CI = 0.61-1.56). However, we observed significant differences in the association with menstrual cycle irregularity and risk of ovarian cancer subtypes (p_{heterogeneity}  = 0.03) as well as by BMI and OC use (p_interaction  < 0.01). Most notable, menstrual cycle irregularity was associated with a decreased risk of high grade serous tumors but an increased risk of serous borderline tumors among women who had never used OCs and those who were overweight. Future research in a large collaborative consortium may help clarify these associations.

Associations of urinary cadmium with circulating sex hormone levels in pre- and postmenopausal Japanese women

BACKGROUND

Exposure to cadmium has been suspected as a risk factor for breast cancer. The present study examined the associations between urinary cadmium levels and circulating sex hormone levels that are linked to breast cancer risk in healthy women.

METHODS

The study subjects were 396 premenopausal Japanese women who had regular menstrual cycles less than 40 days long and 207 postmenopausal Japanese women. Urinary cadmium was measured using spot urine samples. Plasma estradiol, testosterone, and dehydroepiandrosterone sulfate were measured. Additionally, the follicle-stimulating hormone, luteinizing hormone, and sex hormone-binding globulin were measured for premenopausal women.

RESULTS

In premenopausal women, the urinary cadmium level either expressed in μg per liter or per g of urine creatinine was significantly inversely associated with total and free testosterone levels after controlling for age, body mass index, smoking status, alcohol intake, and the phase of the menstrual cycle. Total and free testosterone levels were 14.6% and 15.0% lower, respectively, in women in the highest quartile of urinary cadmium per g creatinine in those in the lowest quartile. In postmenopausal women, the urinary cadmium in μg per liter as well as per g creatinine was significantly inversely associated with the estradiol level after controlling for covariates. The estradiol level was 25.8% lower in women in the highest tertile of urinary cadmium per g creatinine than in those in the lowest tertile.

CONCLUSIONS

The data suggest inverse associations between urinary cadmium and the plasma estradiol or testosterone level in Japanese women.

Cross-Sectional Associations between Body Size, Circulating Sex-Steroid Hormones and IGF Components among Healthy Chinese Women

The incidence of breast cancer has increased in Asian countries and rates of hormone receptor (HR) negative breast cancer exceed those of Western countries. Epidemiologic data suggest that the association between body size and BC risk may vary by HR status, and could differ geographically. While body size may influence BC risk by moderating the synthesis and metabolism of circulating sex-steroid hormones, insulin-like growth factor (IGF)-1 and related binding proteins, there is a dearth of literature among Asian women. We aimed to examine these specific associations in a sample of Chinese women. In Sichuan Province 143 women aged ≥40 years were recruited through outpatient services (2011–2012). Questionnaires, anthropometric measurements, and blood samples were utilized for data collection and linear regression was applied in data analyses. Among women <50 years we observed a non-monotonic positive association between body mass index (BMI) and 17β-estradiol, and a reversed J-shaped association between BMI and IGF-1 (p ≤0.05). We observed similar associations between waist-to-hip ratio and these markers. Our finding of augmented IGF-1 among women with low body mass may have implications for understanding breast tumor heterogeneity in diverse populations and should be evaluated in larger prospective studies with cancer outcomes.

Association of hair dye use with circulating levels of sex hormones in premenopausal Japanese women

BACKGROUND

Substances identified as animal carcinogens are no longer used as ingredients of hair dyes. However, hair dyes are diverse groups of chemicals, and certain compounds may affect endogenous sex hormone levels. We examined the association between hair dye use and sex hormone levels among premenopausal women.

METHODS

Study subjects were 431 premenopausal Japanese women who had regular menstrual cycles less than 40 days long. Information on the use of hair dyes or hair bleach, the type of hair coloring used, the duration of use and the frequency of application was collected using a self-administered questionnaire. Fasting plasma samples were obtained to measure estradiol, testosterone, dehydroepiandrosterone sulfate, sex hormone-binding globulin, follicle-stimulating hormone and luteinizing hormone.

RESULTS

After controlling for covariates, the mean plasma total testosterone level was about 14% higher in women who had used hair dyes for 10 or more years than that among women who had never used them (P for trend = 0.02). A similar association was observed when the type of hair dye was restricted to permanent hair dyes. A higher frequency of applying non-permanent hair dyes was marginally significantly associated with higher total and free estradiol levels.

CONCLUSIONS

Data suggest that long-term use of hair dyes may be associated with an increase in circulating testosterone levels. As this is, to our knowledge, the first study examining the association between hair dye use and sex hormone levels, replication of the results is required.

Women who are married or living as married have higher salivary estradiol and progesterone than unmarried women

OBJECTIVES

Extensive research has demonstrated that marriage and parenting are associated with lower testosterone levels in men, however, very little is known about associations with hormone concentrations in women. Two studies have found lower testosterone in relation to pair-bonding and motherhood in women, with several others suggesting that estradiol levels are lower among parous women than nulliparous women. Here, we examine estradiol and progesterone concentrations in relation to marriage and motherhood in naturally cycling, reproductive age women.

METHODS

In 185 Norwegian women, estradiol and progesterone concentrations were assayed from waking saliva samples collected daily over the course of a menstrual cycle. Cycles were aligned on day 0, the day of ovulation. Mean periovulatory estradiol (days -7 to +6) and luteal progesterone (day +2 to +10) indices were calculated. Marital status and motherhood (including age of youngest child) were reported in baseline questionnaires. Multivariable linear regression models were used to examine associations between ovarian hormones, marital status, and motherhood.

RESULTS

Women who were married or living as married had higher estradiol than unmarried women (β = 0.19; 95% CI: 0.02, 0.36) and higher luteal progesterone as well (β = 0.19; 95% CI: -0.01, 0.39). There were no notable differences in hormone levels in relationship to motherhood status.

CONCLUSIONS

Our results indicate that ovarian steroid hormones may be higher among women who are married or living as married, and suggest several possible explanations, however, additional research is needed to elucidate any causal relationships.

Prolactin determinants in healthy women: A large cross-sectional study within the EPIC cohort

BACKGROUND

Experimental and epidemiologic data suggest that higher circulating prolactin is associated with breast cancer risk; however, how various risk factors for breast cancer influence prolactin levels in healthy women is not clear.

METHODS

We analyzed cross-sectional associations between several suggested reproductive and lifestyle risk factors for breast cancer and circulating prolactin among pre- and postmenopausal women, taking into account the use of current postmenopausal hormone therapy, among 2,560 controls from a breast cancer nested case-control study within the EPIC cohort.

RESULTS

Adjusted geometric mean prolactin levels were significantly higher among premenopausal women, and among postmenopausal women using hormone therapy compared with nonusers (8.2, 7.0, and 6.3 ng/mL, respectively; Pcat = <0.0001). Furthermore, prolactin levels were significantly higher among users of combined estrogen-progestin hormone therapy compared with users of estrogen-alone hormone therapy (6.66 vs. 5.90 ng/mL; Pcat = 0.001). Prolactin levels were lower among parous women compared with nulliparous women (8.61 vs. 10.95 ng/mL; Pcat = 0.0002, premenopausal women); the magnitude of this difference depended on the number of full-term pregnancies (22.1% lower, ≥3 vs. 1 pregnancy, Ptrend = 0.01). Results for parity were similar but lower in magnitude among postmenopausal women. Prolactin did not vary by other studied factors, with the exception of lower levels among postmenopausal smokers compared with never smokers.

CONCLUSIONS

Our study shows that current hormone therapy use, especially the use of combined hormone therapy, is associated with higher circulating prolactin levels in postmenopausal women, and confirms prior findings of lower circulating prolactin in parous women.

IMPACT

Our study extends the knowledge linking various breast cancer risk factors with circulating prolactin.

Differences in ovarian hormones in relation to parity and time since last birth

OBJECTIVE

To examine ovarian function in relation to parity and time since last birth.

DESIGN

Cross-sectional study.

SETTING

Health-care program in California.

PATIENT(S)

346 naturally cycling women, aged 18 to 39 years.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Mean follicular urinary estradiol metabolite concentration (E1C) (cycle days -8 to -1), mean luteal progesterone metabolite concentration (PdG) (days 0 to +10), and cycle phase lengths in ovulatory cycles.

RESULT(S)

After the women had collected daily urine samples for up to eight menstrual cycles, we measured the E1C and PdG using enzyme-linked immunoassay. The cycle phase lengths were calculated from the hormone profiles and daily diaries. Women who had given birth within the previous 3 years had lower E1C than the nulliparous women and women who last given birth >3 years earlier. Among the parous women, E1C was positively associated with the time since last birth. Women who last gave birth >3 years earlier had longer follicular phases than the nulliparous women. There were no associations between parity and PdG or luteal phase length.

CONCLUSION(S)

Our cross-sectional data suggest that ovarian function differs in nulliparous and parous women and is positively associated with the time since last birth. Longitudinal research is needed to explore within-woman changes in ovarian function prepartum and postpartum.

Body mass index and breast cancer risk in Japan: a pooled analysis of eight population-based cohort studies

BACKGROUND

A positive association between body mass index (BMI) and breast cancer risk among postmenopausal women has been reported, and a weak inverse association has been suggested among premenopausal women from studies in the Western population. The effects of BMI on breast cancer have remained unclear among the Asian population, especially in premenopausal women.

METHODS

We assessed the associations between BMI and breast cancer incidence by a pooled analysis from eight representative large-scale cohort studies in Japan. Cancer incidence was mainly confirmed through regional population-based cancer registries and/or through active patient notification from major local hospitals. Breast cancer was defined as code C50 according to ICD10. Pooled estimates of the hazard ratios (HRs) and 95% confidence interval (CIs) for breast cancer were calculated using random-effects models.

RESULTS

Analytic subjects were 183 940 women, 1783 of whom had breast cancer during 2 194 211 person-years of follow-up. A positive association between BMI and the risk of postmenopausal breast cancer was observed (trend P<0.001). The HRs for premenopausal breast cancer were 1.05 (95% CI 0.56-1.99), 1.07 (95% CI 0.76-1.52), 0.91 (95% CI 0.64-1.30), 1.15 (95% CI 0.76-1.73), 1.45 (95% CI 0.71-2.94), and 2.25 (95% CI 1.10-4.60), respectively, in BMIs of <19, 19 to <21, 21 to <23, 25 to <27, 27 to <30, and ≥30 kg/m2. These results were not substantially altered after excluding the patients who were diagnosed with breast cancer in the first 2 years of follow-up.

CONCLUSIONS

The increased risk of postmenopausal breast cancer among women with higher BMIs was confirmed in Japanese. A borderline-significant positive association between BMI and premenopausal breast cancer was observed, suggesting that body mass in Asian women might have opposite effects on breast cancer compared with Western women.

Plasma amino acid profiles are associated with biomarkers of breast cancer risk in premenopausal Japanese women

OBJECTIVE

Recently, profiles of plasma amino acids have been utilized to detect diseases including breast cancer. However, there is a possibility that the amino acid status may be associated with the risk of breast cancer. We investigated the relationship of plasma levels of amino acids with levels of sex hormones and insulin-like growth factor (IGF)-1, which are relevant to the etiology of premenopausal breast cancer, in normal premenopausal women.

METHODS

Participants were 350 Japanese women who had regular menstrual cycles less than 40-day long. Fasting plasma samples were assayed for estradiol, testosterone, dehydroepiandrosterone sulfate, sex-hormone-binding globulin (SHBG), and IGF-1. A total of 20 amino acids in plasma were quantified by liquid chromatography-mass spectrometry. Information on lifestyle and reproductive factors was obtained using a self-administered questionnaire.

RESULTS

The plasma arginine level was significantly inversely correlated with plasma levels of total and free estradiol and IGF-1 after adjusting for age, body mass index, and phase of the menstrual cycle. Plasma leucine and tyrosine levels were significantly positively correlated with the free testosterone level. The ratio of plasma asparagine to the total amino acids was significantly positively correlated with SHBG level.

CONCLUSIONS

Plasma levels of some specific amino acids, such as arginine, leucine, tyrosine, and asparagine, were associated with the levels of sex hormones, SHBG, or IGF-1 in premenopausal women. However, the present cross-sectional study cannot provide a cause-effect relation. The implication of amino acids in the etiology of breast cancer needs to be addressed in future studies.

Hormonal determinants of nipple aspirate fluid yield among breast cancer cases and screening controls

BACKGROUND

Nipple aspiration fluid (NAF) use as a biosample is limited by the variable yield across studies. We investigated the endocrine determinants of yield in an ongoing breast cancer case-control study.

METHODS

One-hundred and eighteen women yielding ≥2 μL NAF and 120 non-yielders were included; serum hormones were measured; differences in median hormones were assessed using the Wilcoxon rank-sum test. ORs and 95% confidence intervals (95% CI) for yielder status relative to hormone levels were estimated using logistic regression, adjusting for parity and lactation, and, in premenopausal women, menstrual cycle phase (MCP).

RESULTS

Prolactin concentrations were higher in yielders than non-yielders (premenopausal: 7.6 and 2.5 ng/mL, P < 0.01; postmenopausal 5.3 and 2.2 ng/mL; P < 0.01). Among premenopausal-yielders, estradiol was lower (64.3 vs. 90.5 pg/mL, MCP-adjusted P = 0.02). In separate menopausal status and parity-adjusted models, significant case-control differences persisted in prolactin: case OR 1.93 (95% CI, 1.35-2.77), control OR 1.64 (95% CI, 1.17-2.29). Premenopausal control yielders had higher progesterone (OR, 1.70; 95% CI, 1.18-2.46) and sex-hormone binding-globulin (OR, 2.09; 95% CI, 1.08-4.05) than non-yielders. Among parous women, further adjustment for lactation suggested a stronger positive association of serum prolactin with yield in cases than controls.

CONCLUSION

NAF-yielders show higher prolactin than non-yielders, regardless of menopause and parity; implications of this and other endocrine differences on NAF biomarkers of breast cancer risk deserve further study.

IMPACT

NAF yield is associated with a distinct endocrine environment that must be considered in studies of NAF-based breast cancer risk markers.

Excessive milk production during breast-feeding prior to breast cancer diagnosis is associated with increased risk for early events

Breast-feeding is a known protective factor against breast cancer. Breast-feeding duration is influenced by hormone levels, milk production, and lifestyle factors. The aims were to investigate how breast-feeding duration and milk production affected tumor characteristics and risk for early breast cancer events in primary breast cancer patients. Between 2002 and 2008, 634 breast cancer patients in Lund, Sweden, took part in an ongoing prospective cohort study. Data were extracted from questionnaires, pathology reports, and patients’ charts from 592 patients without preoperative treatment. Breast-feeding duration ≤12 months of the first child was associated with higher frequency of ER+/PgR+ tumors (P=0.02). Median follow-up time was 4.9 years. Higher risk for early events was observed for breast-feeding duration of first child >12 months (LogRank P=0.001), total breast-feeding duration >12 months (LogRank P=0.008), as well as ‘excessive milk production’ during breast-feeding of the first child (LogRank P=0.001). Patients with ‘almost no milk production’ had no events. In a multivariable model including both ‘excessive milk production’ and breast-feeding duration of the first child >12 months, both were associated with a two-fold risk for early events, adjusted HRs 2.33 (95% CI: 1.25-4.36) and 2.39 (0.97-5.85), respectively, while total breast-feeding duration was not. ‘Excessive milk production’ was associated with a two-fold risk of early distant metastases, adjusted HR 2.59 (1.13-5.94), but not duration. In conclusion, ‘excessive milk production’ during breast-feeding was associated with higher risk for early events independent of tumor characteristics, stressing the need to consider host factors in the evaluation of prognostic markers.

Associations between body size and serum estradiol and sex hormone-binding globulin levels in premenopausal African American women

CONTEXT

African American (AA) women have the highest rates of premenopausal breast cancer; however, it is unclear whether body size contributes to the hormonal patterns potentially associated with increased breast cancer risk in these women.

OBJECTIVE

To characterize the association between body size and serum levels of estradiol and sex hormone-binding globulin (SHBG) levels in a sample of premenopausal AA women.

DESIGN

A total of 164 premenopausal AA women who were not pregnant or breastfeeding were recruited for this study. Serum samples were collected during the early follicular phase, and trained staff collected body size measurements. Multiple linear regression models were performed to assess potential associations.

MAIN OUTCOME MEASURES

Serum estradiol and SHBG levels.

RESULTS

Many (81%) of the women enrolled were overweight or obese. Both waist-to-hip ratio (WHR) (β = 2.68, P = .008) and waist circumference (WC) (β = 2.02, P = .046) were positively associated with higher levels of estradiol. All measures of body was significantly and inversely associated with SHBG levels (all P < .05).

CONCLUSIONS

Premenopausal AA women with higher WHR or larger WC may have higher levels of estradiol and lower levels of SHBG. Thus, WHR or WC may be better indicators for assessing hormonal patterns implicated in breast cancer pathogenesis in these women.

Circulating prolactin levels and risk of epithelial ovarian cancer

PURPOSE

Indirect evidence from experimental and epidemiological studies suggests that prolactin may be involved in ovarian cancer development. However, the relationship between circulating prolactin levels and risk of ovarian cancer is unknown.

METHODS

We conducted a nested case-control study of 230 cases and 432 individually matched controls within three prospective cohorts to evaluate whether pre-diagnostic circulating prolactin is associated with subsequent risk of ovarian cancer. We also assessed whether lifestyle and reproductive factors are associated with circulating prolactin among controls.

RESULTS

Prolactin levels were significantly lower among post- versus pre-menopausal women, parous versus nulliparous women, and past versus never users of oral contraceptives in our cross-sectional analysis of controls. In our nested case-control study, we observed a non-significant positive association between circulating prolactin and ovarian cancer risk (OR(Q4vsQ1) 1.56, 95 % CI 0.94, 2.63, p trend 0.15). Our findings were similar in multivariate-adjusted models and in the subgroup of women who donated blood ≥5 years prior to diagnosis. We observed a significant positive association between prolactin and risk for the subgroup of women with BMI ≥25 kg/m(2) (OR(Q4vsQ1) 3.10, 95 % CI 1.39, 6.90), but not for women with BMI <25 kg/m(2) (OR(Q4vsQ1) 0.81, 95 % CI 0.40, 1.64).

CONCLUSIONS

Our findings suggest that prolactin may be associated with increased risk of ovarian cancer, particularly in overweight/obese women. Factors associated with reduced risk of ovarian cancer, such as parity and use of oral contraceptives, were associated with lower prolactin levels, which suggests that modulation of prolactin may be a mechanism underlying their association with risk.

Postpartum remodeling, lactation, and breast cancer risk: summary of a National Cancer Institute-sponsored workshop

The pregnancy-lactation cycle (PLC) is a period in which the breast is transformed from a less-developed, nonfunctional organ into a mature, milk-producing gland that has evolved to meet the nutritional, developmental, and immune protection needs of the newborn. Cessation of lactation initiates a process whereby the breast reverts to a resting state until the next pregnancy. Changes during this period permanently alter the morphology and molecular characteristics of the breast (molecular histology) and produce important, yet poorly understood, effects on breast cancer risk. To provide a state-of-the-science summary of this topic, the National Cancer Institute invited a multidisciplinary group of experts to participate in a workshop in Rockville, Maryland, on March 2, 2012. Topics discussed included: 1) the epidemiology of the PLC in relation to breast cancer risk, 2) breast milk as a biospecimen for molecular epidemiological and translational research, and 3) use of animal models to gain mechanistic insights into the effects of the PLC on breast carcinogenesis. This report summarizes conclusions of the workshop, proposes avenues for future research on the PLC and its relationship with breast cancer risk, and identifies opportunities to translate this knowledge to improve breast cancer outcomes.

Associations of birth weight and physical activity with sex steroids in preschool Japanese children

PURPOSE

We aimed to assess the association of body size at birth or physical activity with sex steroid levels, independent of body mass among young children.

METHODS

The cross-sectional study was conducted in 2006. Subjects were 230 boys and 198 girls, aged 3-6 years. Birth weight was based on parents' reports. Questions about physical activity focused on outdoor playtime. Urinary estrone, estradiol, testosterone, and 5-androstene-3β,17α diol (3β,17α-AED) levels were measured by liquid chromatography-electrospray ionization tandem mass spectrometry. Urinary dehydroepiandrosterone level was measured with a radioimmunoassay.

RESULTS

After adjustments for age and BMI, girls with lower birth weight had higher testosterone (trend p = 0.038) and 3β,17α-AED (trend p = 0.028). Girls with low birth weight and high birth weight had higher estrone (p = 0.014) and estradiol (p = 0.074) than those who had middle birth weight. Boys who were physically active had lower testosterone (p = 0.028) and 3β,17α-AED (p = 0.003) than those who were not active. Girls who were physically active had lower estrone (p = 0.015).

CONCLUSIONS

Sex steroid levels in childhood might be affected by body size at birth or by physical activity during childhood. These effects might differ by sex.

Stimulatory Adrenocortical Effects of a Selective Estrogen Receptor Modulator in Ovariectomized Female Macaques

Here, we report the effects of estrogen and the selective estrogen receptor modulator (SERM) levormeloxifene on adrenocortical measures in ovariectomized female cynomolgus monkeys ( Macaca fascicularis). Animals were randomized into one of five treatment groups, each containing 23 to 26 animals: (1) placebo, (2) 0.016 mg/kg 17β-estradiol (E2), (3) 0.5 mg/kg levormeloxifene (L1), (4) 1.0 mg/kg levormeloxifene (L2), and (5) 5.0 mg/kg levormeloxifene (L3). Treatments were administered orally each day for 18 mo. All doses of levormeloxifene resulted in adrenal weights at least 50% greater than placebo ( p < .0001 for all). The target dose of levormeloxifene (L2) resulted in higher serum concentrations of cortisol (+63%), dehydroepiandrosterone-sulfate (+73%), and androstenedione (+37%) compared with the placebo group ( p < .05 for all). In contrast, E2 resulted in no significant differences in adrenal weight or adrenocortical steroids. Oral E2 and all SERM doses resulted in similar reductions in serum gonadotropins and at least threefold greater uterine weight versus placebo ( p < .0001 for all). Results indicate that the SERM levormeloxifene, in contrast to E2, may have robust stimulatory effects on adrenocortical hormones in a postmenopausal model. These findings warrant further investigation into long-term SERM effects on adrenocortical function.