Parent Estrogens Research Articles

Estrogen Metabolism in Postmenopausal Women Exposed In Utero to Diethylstilbestrol.

Background: Prenatal diethylstilbestrol (DES) exposure is associated with adverse reproductive outcomes and cancer of the breast and vagina/cervix in adult women. DES effects on estrogen metabolism have been hypothesized, but reproductive hormone concentrations and metabolic pathways have not been comprehensively described.Methods: Blood samples were provided by 60 postmenopausal women (40 exposed and 20 unexposed) who were participants in the NCI Combined DES Cohort Study, had never used hormone supplements or been diagnosed with cancer, had responded to the most recent cohort study questionnaire, and lived within driving distance of Boston University Medical School (Boston, MA). Parent estrogens and their metabolites were measured by high-performance liquid chromatography-tandem mass spectrometry. Age-adjusted percent changes in geometric means and associated 95% confidence intervals (CIs) between the exposed and unexposed were calculated.Results: Concentrations of total estrogens (15.3%; CI, -4.1-38.5) and parent estrogens (27.1%; CI, -8.2-76.1) were slightly higher in the DES-exposed than unexposed. Ratios of path2:parent estrogens (-36.5%; CI, -53.0 to -14.3) and path2:path16 (-28.8%; CI, -47.3-3.7) were lower in the DES exposed. These associations persisted with adjustment for total estrogen, years since menopause, body mass index, parity, and recent alcohol intake.Conclusions: These preliminary data suggest that postmenopausal women who were prenatally DES exposed may have relatively less 2 than 16 pathway estrogen metabolism compared with unexposed women.Impact: Lower 2 pathway metabolism has been associated with increased postmenopausal breast cancer risk and could potentially offer a partial explanation for the modest increased risk observed for prenatally DES-exposed women. Cancer Epidemiol Biomarkers Prev; 27(10); 1208-13. ©2018 AACR.

Estrogen Metabolism in Premenopausal Women Is Related to Early Life Body Fatness.

Background: Estrogen metabolism in premenopausal women may be related to early life body fatness.Methods: Premenopausal women participating in the Nurses' Health Study II recalled their body fatness at ages 5, 10, and 20 years using a validated 9-level pictogram. Fifteen estrogens and estrogen metabolites (EM) were measured using LC/MS-MS in luteal phase urines from 603 women ages 32-54 years. Geometric means of individual EM, metabolic pathway groups, and pathway ratios were examined by body fatness categories using linear mixed models.Results: Body fatness at each age was inversely associated with adult concentrations of all EM combined, parent estrogens (estrone, estradiol), and the 2-hydroxylation pathway. Women in the top (vs. bottom) category of body fatness at age 10 had 21% lower levels of all EM (Ptrend = 0.003), 24% lower parent estrogens (Ptrend = 0.002), and 36% lower 2-pathway (Ptrend = 0.0003). Body fatness at age 10 was inversely associated with 2-catechols (35% lower, Ptrend = 0.0004) and 2-methylated catechols (30% lower, Ptrend = 0.002). After adjusting for premenopausal body mass index (BMI), these associations remained inverse but were attenuated; only parent estrogens remained statistically significant (21% lower, Ptrend = 0.01). Body fatness at ages 5 and 20 were similarly, but more weakly, associated with estrogen pathways.Conclusions: Estimates of body fatness during early life were inversely associated with premenopausal levels of all EM combined, parent estrogens, and 2-pathway estrogen metabolites. These relationships were not fully explained by adult BMI.Impact: These findings inform investigations of diseases linked to early life body fatness and estrogen metabolism. Cancer Epidemiol Biomarkers Prev; 27(5); 585-93. ©2018 AACR.

Estradiol metabolites as biomarkers of endometrial cancer prognosis after surgery

Endometrial cancer (EC) is the most common gynecologic malignancy prevailing after menopause. Defining steroid profiles may help predict the risk of recurrence after hysterectomy, which remains limited due to the lack of reliable markers. Adrenal precursors, androgens, parent estrogens and catechol estrogen metabolites were measured by mass spectrometry (MS) in preoperative serums and those collected one month after hysterectomy from 246 newly diagnosed postmenopausal EC cases. We also examined the associations between steroid hormones and EC status by including 110 healthy postmenopausal women. Steroid concentrations were analyzed in relation to clinicopathological features, recurrence and overall survival (OS). The mean follow-up time was 65.5 months and 26 patients experienced relapse after surgery for a recurrence incidence of 10.6% (6.4% Type I and 29.5% Type II). Recurrence and OS were related to a more aggressive disease but not linked to body mass index. Preoperative levels of estriol (E3) and estrone-sulfate (E1-S) were inversely associated with recurrence in a multivariate logistic regression analysis (Hazard ratios (HRs) of 0.31, P=0.039 and 3.01, P=0.024; respectively). All circulating steroids declined considerably after surgery almost reaching those of healthy women, except 4-methoxy-E2 (4MeO-E2) for which postoperative levels increased by 35% and were associated to a 68% decreased risk of recurrence (HR=0.32, P=0.015). Women diagnosed with both histological types of EC present significantly higher levels of steroids, in support of their mitogenic effects. The estrogen precursor E1-S, the anticancer metabolite 4MeO-E2, and E3 that exert mixed antagonist and agonist estrogenic activities and immunological effects, are potential independent prognostic factors.

Abstract A12: Urinary levels of PGE-M and estrogens are independently associated with postmenopausal breast cancer risk

Abstract Prostaglandin E2 (PGE2) induces aromatase expression in adipose tissue leading to increased estrogen production that may promote the development and progression of breast cancer. However, few studies have simultaneously investigated systemic levels of PGE2 and estrogen in relation to postmenopausal breast cancer risk. In a case-cohort study of postmenopausal women (295 cases and 294 subcohort) we previously reported that high levels of PGE-M, a major metabolite of PGE2, were associated with an increased risk of breast cancer among postmenopausal women who did not regularly use nonsteroidal anti-inflammatory drugs (NSAIDs). Here we determined urinary estrogen metabolites (EMs) using mass spectrometry in the same case-cohort set and using linear regression estimated the effect of PGE-M on EMs. Hazard ratios (HRs) for the risk of developing breast cancer in relation to PGE-M and EMs were evaluated in Cox regression models with and without mutual adjustment. PGE-M was a significant predictor of estrone (E1), but not estradiol (E2) levels in multivariable analysis. Elevated E2 levels were associated with an increased risk of developing breast cancer (HRQ5vs.Q1 =1.54, 95% CI: 1.01-2.35), and this association remained unchanged after adjustment for PGE-M (HRQ5vs.Q1 =1.52, 95% CI: 0.99-2.33). Similarly, elevated levels of PGE-M were associated with increased risk of developing breast cancer (HRQ4vs.Q1 =2.01, 95% CI: 1.01-4.29), and this association was only nominally changed after consideration of E1 or E2 levels. Urinary levels of PGE-M and parent estrogens were independently associated with future risk of developing breast cancer among these postmenopausal women. Increased breast cancer risk associated with PGE-M might be attributable both to PGE2-mediated increases in estrogens, and to additional effects related to inflammation. Note: This abstract was not presented at the conference. Citation Format: Sangmi Kim, Jeff Campbell, Wonsuk Yoo, Jack A. Taylor, Dale P. Sandler. Urinary levels of PGE-M and estrogens are independently associated with postmenopausal breast cancer risk. [abstract]. In: Proceedings of the AACR Special Conference: Improving Cancer Risk Prediction for Prevention and Early Detection; Nov 16-19, 2016; Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(5 Suppl):Abstract nr A12.

Anthropometric measures and serum estrogen metabolism in postmenopausal women: the Women\u2019s Health Initiative Observational Study

BackgroundSeveral anthropometric measures have been associated with hormone-related cancers. However, it is unknown whether estrogen metabolism plays an important role in these relationships. We examined whether measured current body mass index (BMI), waist-to-hip ratio (WHR), height, and self-reported BMI at age 18 years were associated with serum estrogens/estrogen metabolites using baseline, cross-sectional data from 1835 postmenopausal women enrolled in the Women’s Health Initiative Observational Study.MethodsFifteen estrogens/estrogen metabolites were quantified using liquid chromatography-tandem mass spectrometry. Geometric means (GMs) of estrogens/estrogen metabolites (in picomoles per liter) were estimated using inverse probability weighted linear regression, adjusting for potential confounders and stratified on menopausal hormone therapy (MHT) use.ResultsAmong never or former MHT users, current BMI (≥30 vs. <25 kg/m2) was positively associated with parent estrogens (multivariable adjusted GM 432 vs. 239 pmol/L for estrone, 74 vs. 46 pmol/L for estradiol; p-trend < 0.001 for both) and all of the 2-, 4-, and 16-pathway estrogen metabolites evaluated (all p-trend ≤ 0.02). After additional adjustment for estradiol, unconjugated methylated 2-catechols were inversely associated (e.g., 2-methoxyestrone multivariable GM 9.3 vs. 12.0 pmol/L; p-trend < 0.001). Among current MHT users, current BMI was not associated with parent estrogens but was inversely associated with methylated catechols (e.g., 2-methoxyestrone multivariable GM 216 vs. 280 pmol/L; p-trend = 0.008). Similar patterns of association were found with WHR; however, the associations were not independent of BMI. Height and BMI at age 18 years were not associated with postmenopausal estrogens/estrogen metabolite levels.ConclusionsOur data suggest that postmenopausal BMI is associated with increased circulating levels of parent estrogens and reduced methylation of catechol estrogen metabolites, the estrogen metabolism patterns that have previously been associated with higher breast cancer risk.

Association of Estrogen Metabolism with Breast Cancer Risk in Different Cohorts of Postmenopausal Women.

Endogenous estradiol and estrone are linked causally to increased risks of breast cancer. In this study, we evaluated multiple competing hypotheses for how metabolism of these parent estrogens may influence risk. Prediagnostic concentrations of estradiol, estrone, and 13 metabolites were measured in 1,298 postmenopausal cases of breast cancer and 1,524 matched controls in four separate patient cohorts. The median time between sample collection and diagnosis was 4.4 to 12.7 years across the cohorts. Estrogen analytes were measured in serum or urine by liquid chromatography-tandem mass spectrometry. Total estrogen levels (summing all 15 estrogens/estrogen metabolites) were associated strongly and positively with breast cancer risk. Normalizing total estrogen levels, we also found that a relative increase in levels of 2-hydroxylation pathway metabolites, or in the ratio of 2-hydroxylation:16-hydroxylation pathway metabolites, were associated inversely with breast cancer risk. These associations varied by total estrogen levels, with the largest risk reductions occurring in women in the highest tertile. With appropriate validation, these findings suggest opportunities for breast cancer prevention by modifying individual estrogen metabolism profiles through either lifestyle alterations or chemopreventive strategies. Cancer Res; 77(4); 918-25. ©2017 AACR.

Serum Estrogens and Estrogen Metabolites and Endometrial Cancer Risk among Postmenopausal Women.

Although endometrial cancer is clearly influenced by hormonal factors, few epidemiologic studies have investigated the role of endogenous estrogens or especially estrogen metabolites. We conducted a nested case-control study within the Women's Health Initiative Observational Study (WHI-OS), a cohort of 93,676 postmenopausal women recruited between 1993 and 1998. Using baseline serum samples from women who were non-current hormone users with intact uteri, we measured 15 estrogens/estrogen metabolites via HPLC/MS-MS among 313 incident endometrial cancer cases (271 type I, 42 type II) and 354 matched controls, deriving adjusted ORs and 95% confidence intervals (CI) for overall and subtype-specific endometrial cancer risk. Parent estrogens (estrone and estradiol) were positively related to endometrial cancer risk, with the highest risk observed for unconjugated estradiol (OR 5th vs. 1st quintile = 6.19; 95% CI, 2.95-13.03, Ptrend = 0.0001). Nearly all metabolites were significantly associated with elevated risks, with some attenuation after adjustment for unconjugated estradiol (residual risks of 2- to 3-fold). Body mass index (kg/m(2), BMI) relations were somewhat reduced after adjustment for estrogen levels. The association with unconjugated estradiol was stronger for type I than type II tumors (Phet = 0.01). Parent estrogens as well as individual metabolites appeared to exert generalized uterotropic activity, particularly for type I tumors. The effects of obesity on risk were only partially explained by estrogens. These findings enhance our understanding of estrogen mechanisms involved in endometrial carcinogenesis but also highlight the need for studying additional markers that may underlie the effects on risk of certain risk factors, for example, obesity. Cancer Epidemiol Biomarkers Prev; 25(7); 1081-9. ©2016 AACR.

Endogenous Estrogens, Estrogen Metabolites, and Breast Cancer Risk in Postmenopausal Chinese Women

The role of estrogen metabolism in determining breast cancer risk and differences in breast cancer rates between high-incidence and low-incidence nations is poorly understood. We measured urinary concentrations of estradiol and estrone (parent estrogens) and 13 estrogen metabolites formed by irreversible hydroxylation at the C-2, C-4, or C-16 positions of the steroid ring in a nested case-control study of 399 postmenopausal invasive breast cancer case participants and 399 matched control participants from the population-based Shanghai Women's Health Study cohort. Odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer by quartiles of metabolic pathway groups, pathway ratios, and individual estrogens/estrogen metabolites were estimated by multivariable conditional logistic regression. Urinary estrogen/estrogen metabolite measures were compared with those of postmenopausal non-hormone-using Asian Americans, a population with three-fold higher breast cancer incidence rates. All statistical tests were two-sided. Urinary concentrations of parent estrogens were strongly associated with breast cancer risk (ORQ4vsQ1 = 1.94, 95% CI = 1.21 to 3.12, Ptrend = .01). Of the pathway ratios, the 2-pathway:total estrogens/estrogen metabolites and 2-pathway:parent estrogens were inversely associated with risk (ORQ4vsQ1 = 0.57, 95% CI = 0.35 to 0.91, Ptrend = .03, and ORQ4vsQ1 = 0.61, 95% CI = 0.37 to 0.99, Ptrend = .04, respectively). After adjusting for parent estrogens, these associations remained clearly inverse but lost statistical significance (ORQ4vsQ1 = 0.65, 95% CI = 0.39 to 1.06, Ptrend = .12 and ORQ4vsQ1 = 0.76, 95% CI = 0.44 to 1.32, Ptrend = .28). The urinary concentration of all estrogens/estrogen metabolites combined in Asian American women was triple that in Shanghai women. Lower urinary parent estrogen concentrations and more extensive 2-hydroxylation were each associated with reduced postmenopausal breast cancer risk in a low-risk nation. Markedly higher total estrogen/estrogen metabolite concentrations in postmenopausal United States women (Asian Americans) than in Shanghai women may partly explain higher breast cancer rates in the United States.

Circulating Estrogens and Postmenopausal Ovarian Cancer Risk in the Women's Health Initiative Observational Study.

Hormonal and reproductive factors contribute to the development of ovarian cancer, but few studies have examined associations between circulating estrogens and estrogen metabolites and ovarian cancer risk. We evaluated whether serum estrogens and estrogen metabolite levels are associated with ovarian cancer risk among postmenopausal women in a nested case-control study in the Women's Health Initiative (WHI) Observational Study (OS). We selected all 169 eligible epithelial ovarian cancer cases and 412 matched controls from women enrolled in WHI-OS who were not using menopausal hormones at baseline. Baseline levels of 15 estrogens and estrogen metabolites were measured via liquid chromatography/tandem mass spectrometry. Associations with ovarian cancer risk overall and stratified by histologic subtype (serous/nonserous) were analyzed using logistic regression. The mean time from serum collection to cancer diagnosis was 6.9 years. Overall, we observed modest ovarian cancer risk associations among women with higher levels of estrone [OR (95% confidence interval) quintile (Q)5 vs. Q1: 1.54 (0.82-2.90), Ptrend = 0.05], as well as 2- and 4-methoxyestrone metabolites [2.03 (1.06-3.88), Ptrend = 0.02; 1.86 (0.98-3.56), Ptrend = 0.01, respectively]. Associations of estrogens and estrogen metabolites varied substantially by histologic subtype. Associations with serous tumors were universally null, while estrone [2.65 (1.09-6.45), Ptrend = 0.01, Pheterogeneity = 0.04], unconjugated estradiol [2.72 (1.04-7.14), Ptrend = 0.03, Pheterogeneity = 0.02] and many of the 2-, 4-, and 16-pathway metabolites were positively associated with nonserous tumors. Our study provides novel molecular data showing an association of the parent estrogens and several estrogen metabolites with nonserous ovarian cancers. These findings further support the heterogeneous etiology of ovarian cancer. Cancer Epidemiol Biomarkers Prev; 25(4); 648-56. ©2016 AACR.

Association of Active and Sedentary Behaviors with Postmenopausal Estrogen Metabolism.

Physical activity may reduce endogenous estrogens, but few studies have assessed effects on estrogen metabolism and none have evaluated sedentary behavior in relation to estrogen metabolism. We assessed relationships between accelerometer-measured physical activity and sedentary behavior and 15 urinary estrogens and estrogen metabolites (EM) among postmenopausal controls from a population-based breast cancer case-control study conducted in Poland (2000-2003). Postmenopausal women (N = 542) were ages 40 to 72 yr and not currently using hormone therapy. Accelerometers, worn for 7 d, were used to derive measures of average activity (counts per day) and sedentary behavior (<100 counts per minute per day). Estrogen metabolites were measured in 12-h urine samples using liquid chromatography-tandem mass spectrometry. Estrogen metabolites were analyzed individually, in metabolic pathways (C-2, -4, or -16), and as ratios relative to parent estrogens. Geometric means of estrogen metabolites by tertiles of accelerometer-measures, adjusted for age and body mass, were computed using linear models. High activity was associated with lower levels of estrone and estradiol (P trend = 0.01), whereas increased sedentary time was positively associated with these parent estrogens (P trend = 0.04). Inverse associations were observed between high activity and 2-methoxyestradiol, 4-methoxyestradiol, 17-epiestriol, and 16-epiestriol (P trend = 0.03). Sedentary time was positively associated with methylated catechols in the 2- and 4-hydroxylation pathways (P trend ≤ 0.04). Women in the highest tertile of activity had increased hydroxylation at the C-2, -4, and -16 sites relative to parent estrogens (P trend ≤ 0.02), whereas increased sedentary time was associated with a lower 16-pathway/parent estrogen ratio (P trend = 0.01). Higher activity was associated with lower urinary estrogens, possibly through increased estrogen hydroxylation and subsequent metabolism, whereas sedentary behavior may reduce metabolism.

Estrogen Metabolism and Risk of Postmenopausal Endometrial and Ovarian Cancer: the B ∼ FIT Cohort.

Estrogen metabolites may have different genotoxic and mitogenic properties yet their relationship with endometrial and ovarian cancer risk remains unclear. Within the Breast and Bone Follow-up to the Fracture Intervention Trial (B ∼ FIT, n = 15,595), we conducted a case-cohort study to evaluate 15 pre-diagnostic serum estrogens and estrogen metabolites with risk of incident endometrial and ovarian cancer among postmenopausal women not on hormone therapy. Participants included 66 endometrial and 67 ovarian cancer cases diagnosed during follow-up (∼ 10 years) and subcohorts of 346 and 416 women, respectively, after relevant exclusions. Serum concentrations were measured by liquid chromatography-tandem mass spectrometry. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard regression. Exposures were categorized in tertiles (T) and analyzed individually, as metabolic pathways (C-2, -4, or -16) and as ratios to parent estrogens (estradiol, estrone). Estradiol was significantly associated with increased endometrial cancer risk (BMI-adjusted HRT3vsT1 = 4.09, 95% CI 1.70, 9.85; p trend = 0.003). 2-Hydroxyestrone and 16α-hydroxyestrone were not associated with endometrial risk after estradiol adjustment (2-OHE1:HRT3vsT1 = 1.97, 95% CI 0.78, 4.94; 16-OHE1:HRT3vsT1 = 1.50, 95% CI 0.65, 3.46; p trend = 0.16 and 0.36, respectively). Ratios of 2- and 4-pathway catechol-to-methylated estrogens remained positively associated with endometrial cancer after BMI or estradiol adjustment (2-pathway catechols-to-methylated: HRT3vsT1 = 4.02, 95% CI 1.60, 10.1; 4-pathway catechols-to-methylated: HRT3vsT1 = 4.59, 95% CI 1.64, 12.9; p trend = 0.002 for both). Estrogens and estrogen metabolites were not associated with ovarian cancer risk; however, larger studies are needed to better evaluate these relationships. Estrogen metabolism may be important in endometrial carcinogenesis, particularly with less extensive methylation of 2- or 4-pathway catechols associated with elevated endometrial cancer risk.

Estrogen Metabolites Are Not Associated with Colorectal Cancer Risk in Postmenopausal Women

A potential protective role for estrogen in colon carcinogenesis has been suggested based on exogenous hormone use, but it is unclear from previous studies whether endogenous estrogens are related to colorectal cancer risk. These few prior studies focused on parent estrogens; none evaluated effects of estrogen metabolism in postmenopausal women. We followed 15,595 women (ages 55-80 years) enrolled in the Breast and Bone Follow-up to the Fracture Intervention Trial (B∼FIT) who donated blood between 1992 and 1993 for cancer through December 2004. A panel of 15 estrogen metabolites (EM), including estradiol and estrone, were measured in serum from 187 colorectal cancer cases and a subcohort of 501 women not using exogenous hormones at blood draw. We examined EM individually, grouped by pathway (hydroxylation at the C-2, C-4, or C-16 position) and by ratios of the groupings using Cox proportional hazards regression models. No significant associations were seen for estrone (HRQ4 vs. Q1 = 1.15; 95% CI, 0.69-1.93; Ptrend = 0.54), estradiol (HRQ4 vs. Q1 = 0.98; 95% CI, 0.58-1.64; Ptrend > 0.99), or total EM (the sum of all EM; HRQ4 vs. Q1 = 1.35; 95% CI, 0.81-2.24; Ptrend = 0.33). Most metabolites in the 2-, 4-, or 16-pathway were unrelated to risk, although a borderline trend in risk was associated with high levels of 17-epiestriol. Circulating estrogens and their metabolites were generally unrelated to colorectal cancer risk in postmenopausal women. Additional studies are needed to understand how exogenous estrogen may prevent colorectal cancer.

Relationship of serum estrogens and metabolites with area and volume mammographic densities.

Elevated mammographic density is a breast cancer risk factor, which has a suggestive, but unproven, relationship with increased exposure to sex steroid hormones. We examined associations of serum estrogens and estrogen metabolites with area and novel volume mammographic density measures among 187 women, ages 40-65, undergoing diagnostic breast biopsies at an academic facility in Vermont. Serum parent estrogens, estrone and estradiol, and their 2-, 4-, and 16-hydroxylated metabolites were measured using liquid chromatography-tandem mass spectrometry. Area mammographic density was measured in the breast contralateral to the biopsy using thresholding software; volume mammographic density was quantified using a density phantom. Linear regression was used to estimate associations of estrogens with mammographic densities, adjusted for age and body mass index, and stratified by menopausal status and menstrual cycle phase. Weak, positive associations between estrogens, estrogen metabolites, and mammographic density were observed, primarily among postmenopausal women. Among premenopausal luteal phase women, the 16-pathway metabolite estriol was associated with percent area (p = 0.04) and volume (p = 0.05) mammographic densities and absolute area (p = 0.02) and volume (p = 0.05) densities. Among postmenopausal women, levels of total estrogens, the sum of parent estrogens, and 2-, 4- and 16-hydroxylation pathway metabolites were positively associated with area density measures (percent: p = 0.03, p = 0.04, p = 0.01, p = 0.02, p = 0.07; absolute: p = 0.02, p = 0.02, p = 0.01, p = 0.02, p = 0.03, respectively) but not volume density measures. Our data suggest that serum estrogen profiles are weak determinants of mammographic density and that analysis of different density metrics may provide complementary information about relationships of estrogen exposure to breast tissue composition.

Associations of the fecal microbiome with urinary estrogens and estrogen metabolites in postmenopausal women.

The gut microbiota may influence the risk of breast cancer through effects on endogenous estrogens. The objective of the study was to investigate whether urinary estrogens and estrogen metabolites are associated with the diversity and composition of the fecal microbiome. This was a cross-sectional study among women enrolled in Kaiser Permanente of Colorado. A total of 60 women drawn from a random sample of healthy postmenopausal women (aged 55-69 y), without current or recent use of antibiotics or hormone therapy and no history of cancer or gastrointestinal disease participated in the study. OUTCOME MEASURES AND METHODS: Creatinine-standardized urinary estrogens (estrone and estradiol) and 13 hydroxylated estrogen metabolites were measured in spot urines by liquid chromatography-tandem mass spectrometry. The fecal microbiome was assessed using pyrosequencing of 16S rRNA amplicons. General linear models were used to test for associations of diversity and composition of the fecal microbiome with parent estrogen (estrone + estradiol), total estrogens, and estrogen metabolites and the ratio of estrogen metabolites to parent estrogen, which has been predictive of postmenopausal breast cancer risk in previous studies. The ratio of metabolites to parents was directly associated with whole-tree phylogenetic diversity (R = 0.35, P = .01). Relative abundances of the order Clostridiales (R = 0.32, P = .02) and the genus Bacteroides (R = -0.30, P = .03) were also correlated with the ratio of metabolites to parents. Associations were independent of age, body mass index, and study design factors. Our data suggest that women with a more diverse gut microbiome exhibit an elevated urinary ratio of hydroxylated estrogen metabolites to parent estrogen. Further research is warranted to confirm and relate these findings to clinical disease.

Evaluating Removal of Steroid Estrogens by a Model Alga as a Possible Sustainability Benefit of Hypothetical Integrated Algae Cultivation and Wastewater Treatment Systems

The wastewater treatment field is increasing its emphasis on energy and resource recovery, while still prioritizing environmental protection. In this vein, there is growing interest in integration of algae cultivation and wastewater as a means to produce bioenergy while also removing dissolved nutrients. This paper assesses algae-mediated removal of estrogenic steroid hormones, which is an important but previously undocumented water quality benefit for municipal and livestock waste treatment facilities, because these entities discharge significant amounts of estrogens and nutrients. Bench-scale experiments were used to investigate apparent removal of four steroid hormones by a model alga, Scenedesmus dimorphus. Removal efficiencies were roughly 85% for 17α-estradiol and estrone and 95% for 17β-estradiol and estriol over eight days. Sorption, direct-photolysis, and algae-mediated biotransformation were evaluated as possible removal mechanisms. Removal was mainly achieved by algae-mediated biotransformation, and a partial mechanism has been proposed based on observed products. A bioassay indicates that removal of the parent estrogens does not always remove estrogenic activity, although estrogenicity associated with 17β-estradiol did decrease slightly. Overall, this study highlights a novel synergy between water and energy sustainability in integrated algae farming and wastewater treatment systems. These systems should be studied further to see if energy production could motivate voluntary removal of currently unregulated emerging contaminants.

Abstract 1603: Estrogen metabolites and colorectal cancer risk in postmenopausal women in the Breast and Bone Follow-up to the Fracture Intervention Trial (B∼FIT)

Abstract Background: A role for estrogen in colon carcinogenesis is suggested by the lower incidence of colorectal cancer (CRC) in women than men; the protective effect of exogenous hormones on risk; and reduced levels of estrogen receptor beta (ERβ) expression, the predominant ER in the colon, in cancerous compared to healthy colonic tissue. Nonetheless, the few cohort studies of endogenous hormones have not found reduced risks associated with circulating estradiol or estrone levels in postmenopausal women. We hypothesized that specific metabolites in the estrogen metabolic pathway may preferentially bind to and activate colonic ERβ, and analyzed a panel of 15 estrogen metabolites (EM), including estradiol and estrone, in a case-cohort study of CRC. Methods: We prospectively followed 15,595 women enrolled in B∼FIT (Breast and Bone Follow-up to the Fracture Intervention Trial (FIT)) who had completed questionnaires and donated blood between 1992 and 1993 for incident CRC through December 2004. Using liquid chromatography-tandem mass spectrometry, EM were measured in serum from 197 CRC cases and a subcohort of 491 women who were not using exogenous hormones at the time of blood draw. EM were examined individually, grouped by pathway (hydroxylation at the C-2, C-4, or C-16 positions of the steroid ring), and by ratios of the groupings. Cox proportional hazard regression models adjusted for clinical site and age (grouped in ten year intervals) were used to calculate quartile-specific hazard ratios (HRs) and 95% confidence intervals (CIs). Results: Significant risks were not observed for individual EM, and HR for quartiles of total EM (sum of all EM) were elevated but not significant (HRQ4 v Q1=1.23, 95% CI=0.8-2.0, ptrend=0.53). No associations were seen for estrone (HRQ4 v Q1=1.05, 95% CI=0.6-1.7) or estradiol (HRQ4 v Q1=0.90. 95% CI=0.5-1.5). When represented as a ratio to the parent estrogens (estrone and estradiol), risks of CRC for women with higher levels of 2-pathway EM or 4-pathway EM were reduced in each quartile, but neither HR nor trends were significant (ratio 2-pathway: parent, HRQ4 v Q1=0.88, 95 CI=0.6-1.4 ptrend=0.56; ratio 4-pathway: parent, HRQ4 v Q1=0.92, 95% CI=0.6, 1.5 ptrend=0.46). Conclusions: Levels of circulating estrone and estradiol and their metabolites are not associated with CRC risk in the B∼FIT cohort. Citation Format: Roni T. Falk, Cher M. Dallal, James V. Lacey, Douglas C. Bauer, Diana SM Buist, Jane A. Cauley, Trisha F. Hue, Andrea LaCroix, Jeffrey A. Tice, Ruth M. Pfeiffer, Xia Xu, Timothy D. Veenstra, Louise A. Brinton. Estrogen metabolites and colorectal cancer risk in postmenopausal women in the Breast and Bone Follow-up to the Fracture Intervention Trial (B∼FIT). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1603. doi:10.1158/1538-7445.AM2014-1603

Circulating estrogen metabolites and risk of breast cancer in postmenopausal women.

It has been hypothesized that predominance of the 2-hydroxylation estrogen metabolism pathway over the 16α-hydroxylation pathway may be inversely associated with breast cancer risk. We examined the associations of invasive breast cancer risk with circulating 2-hydroxyestrone (2-OHE1), 16α-hydroxyestrone (16α-OHE1), and the 2-OHE1:16α-OHE1 ratio in a case-control study of postmenopausal women nested within two prospective cohorts: the New York University Women's Health Study (NYUWHS) and the Northern Sweden Mammary Screening Cohort (NSMSC), with adjustment for circulating levels of estrone, and additional analyses by tumor estrogen receptor (ER) status. Levels of 2-OHE1 and 16α-OHE1 were measured using ESTRAMET 2/16 assay in stored serum or plasma samples from 499 incident breast cancer cases and 499 controls, who were matched on cohort, age, and date of blood donation. Overall, no significant associations were observed between breast cancer risk and circulating levels of 2-OHE1, 16α-OHE1, or their ratio in either cohort and in combined analyses. For 2-OHE1, there was evidence of heterogeneity by ER status in models adjusting for estrone (P ≤ 0.03). We observed a protective association of 2-OHE1 with ER+ breast cancer [multivariate-adjusted OR for a doubling of 2-OHE1, 0.67 (95% confidence interval [CI], 0.48-0.94; P = 0.02)]. In this study, higher levels of 2-OHE1 were associated with reduced risk of ER+ breast cancer in postmenopausal women after adjustment for circulating estrone. These results suggest that taking into account the levels of parent estrogens and ER status is important in studies of estrogen metabolites and breast cancer.

Circulating estrogens and estrogens within the breast among postmenopausal BRCA1/2 mutation carriers.

Accurately quantifying parent estrogens (PE) estrone (E1) and estradiol (E2) and their metabolites (EM) within breast tissue and serum may permit detailed investigations of their contributions to breast carcinogenesis among BRCA1/2 mutation carriers. We conducted a study of PE/EM in serum, nipple aspirate fluid (NAF), and ductal lavage supernatant (DLS) among postmenopausal BRCA1/2 mutation carriers. PE/EM (conjugated and unconjugated) were measured in paired serum/NAF (n = 22 women) and paired serum/DLS samples (n = 24 women) using quantitative liquid chromatography-tandem mass spectrometry (LC/MS/MS). The relationships between serum and tissue-specific PE/EM were measured using Pearson's correlation coefficients. Conjugated forms of PE/EM constituted the majority of estrogen in serum (88 %), NAF (59 %) and DLS (69 %). PE/EM in NAF and serum were highly correlated [E1 (r = 0.97, p < 0.0001), E2 (r = 0.90, p < 0.0001) and estriol (E3) (r = 0.74, p < 0.0001)] as they were in DLS and serum [E1 (r = 0.92, p < 0.0001; E2 (r = 0.70, p = 0.0001; E3 (r = 0.67, p = 0.0004)]. Analyses of paired total estrogen values for NAF and serum, and DLS and serum yielded ratios of 0.22 (95 % CI 0.19-0.25) and 0.28 (95 % CI 0.24-0.32), respectively. This report is the first to employ LC/MS/MS to quantify PE/EM in novel breast tissue-derived biospecimens (i.e., NAF and DLS). We demonstrate that circulating PE and EM are strongly and positively correlated with tissue-specific PE and EM measured in NAF and DLS among postmenopausal BRCA1/2 mutation carriers. If confirmed, future etiologic studies could utilize the more readily obtainable serum hormone levels as a reliable surrogate measure of exposure at the tissue level.

Estrogen metabolism and breast cancer risk among postmenopausal women: a case–cohort study within B~FIT

Although elevated circulating estrogens are associated with increased postmenopausal breast cancer risk, less is known regarding the role of estrogen metabolism in breast carcinogenesis. We conducted a case-cohort study within the Breast and Bone Follow-up to the Fracture Intervention Trial to assess serum estrogens and estrogen metabolites (EMs) in 407 incident breast cancer cases diagnosed during follow-up and a subcohort of 496 women. In 1992-93, women completed a baseline questionnaire and provided blood samples. Hazard ratios (HRs) and 95% confidence intervals (CIs), adjusted for geography and trial participation status, were estimated using Cox proportional hazard regression. Serum concentrations of EMs were measured by liquid chromatography-tandem mass spectrometry. EMs (quintiles, Q) were analyzed individually, as metabolic pathways (C-2, -4 or -16) and as ratios. Elevated circulating estradiol was associated with increased breast cancer risk (HRQ5vsQ1 = 1.86; 95% CI: 1.19-2.90; P trend = 0.04). An elevated ratio of the 2-hydroxylation pathway (HRQ5vsQ1 = 0.69; 95% CI: 0.46-1.05; P trend = 0.01) and 4-hydroxylation pathway (HRQ5vsQ1 = 0.61; 95% CI: 0.40-0.93; P trend = 0.004) to parent estrogens (estradiol and estrone) was inversely associated with risk. A higher ratio of the 2/16-hydroxylation pathways was associated with reduced risk (HRQ5vsQ1 = 0.60; 95% CI: 0.40-0.90; P trend = 0.002). Increased 2- or 4-hydroxylation of parent estrogens may lower risk of postmenopausal breast cancer. Analyses of metabolic pathways may help elucidate the role of estrogen metabolism in breast carcinogenesis.

Abstract A53: Estrogen metabolism in relation to the risk of aggressive prostate cancer

Abstract Introduction and Objective: Existing epidemiologic data do not support an association between circulating levels of sex steroid hormones and risk of prostate cancer. Although it has been suggested that the combined action of androgens and estrogens'specifically their balance'may play a key role in prostate carcinogenesis, epidemiologic studies to evaluate this hypothesis are sparse, have assessed a limited number of sex steroid hormones, and have provided inconsistent results. We investigated associations between serum sex hormones'with a particular focus on estrogen metabolites'and risk of aggressive prostate cancer. Study Population, Design and Methods: In a case-control study nested within the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, we measured 15 parent serum estrogens (estrone and estradiol) and estrogen metabolites, including those in the C-2, -4, or 16 hydroxylation pathways, using a liquid chromatography-tandem mass spectrometry (LC/MS/MS) assay. Cases (n=195) were defined as non-Hispanic white men diagnosed with aggressive prostate cancer (stage III or IV and/or Gleason ≥7) between and 1994 and 2009 who were 55–70 years at diagnosis. Controls (n=195) were non-Hispanic white men who were free from prostate cancer for the duration of follow-up and frequency-matched to cases by age at study entry (5-yr intervals), time since baseline screen (1-yr time windows) and year of blood draw. Only cases and controls included in a previous study that measured serum androgens and sex-hormone binding globulin (SHBG) were eligible. Logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (95%CI). Results: Individual parent estrogens and individual estrogen metabolites were unrelated to risk of aggressive prostate cancer; with the exception of a non-linear inverse relationship between cancer and levels of methylated catechols, namely 2- and 4-methoxyestrone. However, there was an increased risk of aggressive prostate cancer associated with an increasing ratio of 2:16 hydroxyestrone (fourth vs. first quartile: OR 2.44, 95% CI 1.34–4.45, p trend=0.001) and a strong trend of decreasing prostate cancer risk with an increasing ratio of estradiol to testosterone (fourth vs. first quartile: OR 0.27, 95% CI 0.12–0.59, p trend=0.003). Conclusion: We observed a strong protective effect of higher serum estradiol to testosterone levels in relation to risk of aggressive prostate cancer. Men with higher concentrations of methylated catechols in the 2- and 4-hydroxylation pathway may have a reduced risk of aggressive prostate cancer, while those with higher ratios of 2:16 hydroxyestrone may be at increased risk. These findings suggest a role for sex steroid hormone metabolism in prostate carcinogenesis. Citation Format: Amanda Black, Paul F. Pinsky, Robert L. Grubb, III, Roni T. Falk, Ann W. Hsing, Lisa W. Chu, Tamra E. Meyer, Tim Veenstra, Xia Xu, Kai Yu, Louise A. Brinton, Robert N. Hoover, Michael B. Cook. Estrogen metabolism in relation to the risk of aggressive prostate cancer. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr A53.