BACKGROUND: Little is known about relationships among reproductive factors, estrogens and estrogen metabolites (jointly referred to as EM), and estrogen metabolism patterns.METHODS: In a cross-sectional analysis, we examined the associations of age at menarche, menstrual cycle length and regularity, parity, age at first and last birth, breastfeeding, and duration of and time since use of oral contraceptives (OC) with mid-luteal phase urinary EM in a sample of 603 premenopausal women, ages 33-51, within the Nurses' Health Study II (NHSII). Fifteen individual urinary EM were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and analyzed both individually and in metabolic pathways.RESULTS: Compared to women with extremely regular cycles, those with irregular cycles had lower levels of total EM (percent difference=24%; ptrend=0.01), estradiol (23%; ptrend=0.02), and 16-hydroxylation pathway EM (32%; ptrend<0.01). Longer menstrual cycles were associated with higher levels of estrone (percent difference ≥32 vs.<26 days: 25%; ptrend=0.03), estradiol (24%; ptrend=0.01), and 16-hydroxylation pathway EM (22%; ptrend=0.02). Among parous women, older age at first birth was associated with lower 16-hydroxylation pathway EM (percent difference age at first birth ≥35 vs. ≤25 years: 20%; ptrend=0.02). The other reproductive factors were not statistically significantly associated with individual urinary EM or EM pathways. Conclusions and Impact: These data, based on a LC-MS/MS assay with high specificity and precision, provide an initial, comprehensive evaluation of the associations between reproductive factors and estrogen metabolism patterns.

Epidemiological and other evidence suggests that vitamin D may be protective against several chronic diseases. Assessing vitamin D status in epidemiological studies, however, is challenging given finite resources and limitations of commonly used approaches. Using multivariable linear regression, we derived predicted 25-hydroxyvitamin D (25(OH)D) scores based on known determinants of circulating 25(OH)D, including age, race, UV-B radiation flux at residence, dietary and supplementary vitamin D intakes, BMI, physical activity, alcohol intake, post-menopausal hormone use (women only) and season of blood draw, in three nationwide cohorts: the Nurses' Health Study, Nurses' Health Study II and the Health Professionals Follow-up Study. The model r2 for each cohort ranged from 0·25 to 0·33. We validated the prediction models in independent samples of participants from these studies. Mean measured 25(OH)D levels rose with increasing decile of predicted 25(OH)D score, such that the differences in mean measured 25(OH)D between the extreme deciles of predicted 25(OH)D were in the range 8·7-12·3 ng/ml. Substituting predicted 25(OH)D scores for measured 25(OH)D in a previously published case-control analysis of colorectal cancer yielded similar effect estimates with OR of approximately 0·8 for a 10 ng/ml difference in either plasma or predicted 25(OH)D. We conclude that these data provide reasonable evidence that a predicted 25(OH)D score is an acceptable marker for ranking individuals by long-term vitamin D status and may be particularly useful in research settings where biomarkers are not available for the majority of a study population.

Endogenous estrogens and estrogen metabolism are hypothesized to be associated with premenopausal breast cancer risk but evidence is limited. We examined 15 urinary estrogens/estrogen metabolites (EM) and breast cancer risk among premenopausal women in a case-control study nested within the Nurses' Health Study II (NHSII). In 1996-1999, urine was collected from 18,521 women during the mid-luteal menstrual phase. Breast cancer cases (N=247) diagnosed between collection and June 2005 were matched to 2 controls each (N=485). Urinary EM were measured by liquid chromatography-tandem mass spectrometry and adjusted for creatinine level. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated by multivariate conditional logistic regression. Higher urinary estrone and estradiol levels were strongly significantly associated with lower risk (top vs. bottom quartile RR estrone=0.52, 95% CI=(0.30-0.88); estradiol=0.51, 95% CI=(0.30-0.86)). Generally inverse, though non-significant, patterns also were observed with 2- and 4-hydroxylation pathway EM. Inverse associations generally were not observed with 16-pathway EM and a significant positive association was observed with 17-epiestriol (top vs. bottom quartile RR=1.74, 95% CI=(1.08-2.81), p-trend=0.01). In addition, there was a significant increased risk with higher 16-pathway/parent EM ratio (comparable RR=1.61, 95% CI=(0.99-2.62), p-trend=0.04). Other pathway ratios were not significantly associated with risk except parent EM/non-parent EM (comparable RR=0.58, 95% CI=(0.35-0.96), p-trend=0.03). These data suggest that most mid-luteal urinary EM concentrations are not positively associated with breast cancer risk among premenopausal women. The inverse associations with parent EM and the parent EM/non-parent EM ratio suggest that women with higher urinary excretion of parent estrogens are at lower risk.

ABSTRACT: INTRODUCTION: Experimental evidence indicates vitamin D may play an important role in breast cancer etiology but epidemiologic evidence to date is inconsistent. Vitamin D comes from dietary intake and sun exposure and plasma levels of 25-hydroxyvitamin D (25(OH)D) are considered the best measure of vitamin D status. METHODS: We conducted a prospective nested case-control study within the Nurses' Health Study II (NHSII). Plasma samples collected in 1996 to 1999 were assayed for 25(OH)D in 613 cases, diagnosed after blood collection and before 1 June 2007, and in 1,218 matched controls. Multivariate relative risks (RR) and 95% confidence intervals (CI) were calculated by conditional logistic regression, adjusting for several breast cancer risk factors. RESULTS: No significant association was observed between plasma 25(OH)D levels and breast cancer risk (top vs. bottom quartile multivariate RR = 1.20, 95% CI (0.88 to 1.63), P-value, test for trend = 0.32). Results were similar when season-specific quartile cut points were used. Results did not change when restricted to women who were premenopausal at blood collection or premenopausal at diagnosis. Results were similar between estrogen receptor (ER)+/progesterone receptor (PR)+ and ER-/PR- tumors (P-value, test for heterogeneity = 0.51). The association did not vary by age at blood collection or season of blood collection, but did vary when stratified by body mass index (P-value, test for heterogeneity = 0.01). CONCLUSIONS: Circulating 25(OH)D levels were not significantly associated with breast cancer risk in this predominantly premenopausal population.

Overweight and obesity are inversely related to the risk of breast cancer among premenopausal women. We assessed the association between adult weight change since age 18 years with the risk of breast cancer among premenopausal women to explore whether weight gain was associated with a decrease in risk and weight loss was associated with an increase in risk. A total of 56,223 premenopausal participants in the Nurses' Health Study and 109,385 premenopausal participants in the Nurses' Health Study II were prospectively followed for up to 32 years and 18 years, respectively, and weight change since age 18 years was assessed biennially. The incidence of invasive breast cancer was assessed throughout follow-up. Weight loss of 5 kg or more since age 18, maintained for at least 4 years, was related to lower incidence of premenopausal breast cancer, compared to maintaining a stable weight, but this relation was of borderline statistical significance (covariate-adjusted HR = 0.75; 95% CI 0.52-1.09). Weight gain since age 18 years was also inversely related to breast cancer incidence among premenopausal women (covariate-adjusted p for trend = 0.01), but the association weakened after controlling for weight at age 18 and did not reach statistical significance (p for trend = 0.08). Although obesity and breast cancer among premenopausal women are inversely related, weight loss since age 18 years did not increase and weight gain did not significantly decrease the risk of premenopausal breast cancer among participants in the large prospective cohorts of NHS and NHS II.

BACKGROUND: Temporal variability of biomarkers should be evaluated before their use in epidemiologic studies. METHODS: We evaluated the reproducibility, using intraclass correlation coefficients (ICC), of 77 plasma and 9 urinary biomarkers over 1 to 3 years among premenopausal (n = 40) and postmenopausal (n = 35-70) participants from the Nurses' Health Study and Nurses' Health Study II. RESULTS: Plasma and urinary stress hormones and melatonin were measured among premenopausal women, whereas melatonin and the remaining biomarkers were measured in postmenopausal women. ICCs were good to excellent for plasma carotenoids (0.73-0.88), vitamin D analytes (0.56-0.72), bioactive somatolactogens (0.62), soluble leptin receptor (0.82), resistin (0.74), and postmenopausal melatonin (0.63). Reproducibility was lower for some of the plasma fatty acids (0.38-0.72), matrix metalloproteinases (0.07-0.91), and premenopausal melatonin (0.44). The ICCs for plasma and urinary phytoestrogens were poor (</=0.09) except for enterolactone (plasma, 0.44; urinary, 0.52). ICCs for the stress hormones among premenopausal women ranged from 0 (plasma cortisol) to 0.45 (urinary dopamine). CONCLUSIONS: Our results indicate that for the majority of these markers, a single measurement can reliably estimate average levels over a 1- to 3-year period in epidemiologic studies. For analytes with fair to good ICCs, reproducibility data can be used for measurement error correction. Analytes with poor ICCs should only be used in settings with multiple samples per subject or in populations in which ICCs are higher. Impact: This article summarizes the feasibility of the use of >80 biomarkers in epidemiologic studies in which only one biospecimen is available to represent longer term exposure. Cancer Epidemiol Biomarkers Prev; 19(4); OF1-9.

Prior epidemiologic studies suggest that regular use of analgesics may decrease risk of breast and ovarian cancer. We explored possible hormone-mediated mechanisms for these associations by examining the relationship between use of aspirin, nonaspirin nonsteroidal anti-inflammatory drugs (NSAID), and acetaminophen and sex steroid hormone concentrations among 740 postmenopausal women in the Nurses' Health Study. All women reported their analgesic use in 1988 or 1990 and provided a blood sample in 1989 to 1990. We calculated adjusted geometric mean estrogen and androgen levels for each category of analgesic use and calculated the P value for trend with increasing frequency of use. There was no association between days of use per month of aspirin, nonaspirin NSAIDs, or acetaminophen in 1990 and hormone levels (all P(trend)>/= 0.09). However, we observed significant inverse trends between the estimated number of aspirin tablets per month in 1988 and concentrations of estrone (P(trend)= 0.04) and estrone sulfate (P(trend)= 0.03). In analyses of total (aspirin and nonaspirin) NSAID use in 1990, women who used NSAIDs at least 15 days per month had significantly lower levels of estradiol compared with women with no NSAID use (P(trend)= 0.03). Frequency of use of all analgesics (aspirin, nonaspirin NSAIDs, and acetaminophen) in 1990 was inversely associated with concentrations of estradiol (P(trend)= 0.001), free estradiol (P(trend)= 0.01), estrone sulfate (P(trend)= 0.03), and the ratio of estradiol to testosterone (P(trend)= 0.04). Among postmenopausal women, regular users of aspirin and other analgesics may have lower estrogen levels than nonusers, which could contribute to a decreased risk of breast or ovarian cancer among analgesic users. Cancer Epidemiol Biomarkers Prev; 19(4); OF1-9.

Endogenous estrogens play an integral role in the etiology of breast, endometrial, and, possibly, ovarian cancers. Estrogen metabolism yields products that are potentially both estrogenic and genotoxic, yet individual metabolic patterns are just beginning to be explored in epidemiologic studies. Within the Nurses' Health Study II, we examined reproducibility of 15 urinary estrogens and estrogen metabolites (EM) among 110 premenopausal women with three luteal-phase urine samples collected over 3 years. EM were measured by a recently developed high-performance liquid chromatography-tandem mass spectrometry (LC-MS(2)) method with high sensitivity, specificity, and precision. We assessed Spearman correlations and intraclass correlation coefficients (ICC) across the three samples. Correlations between urinary estrone or estradiol and EM were only modest (r = 0.1-0.5). The 2- and 4-hydroxylation pathways were highly correlated (r = 0.9) but weakly inversely correlated with the 16-hydroxylation pathway (r =-0.2). Within-woman reproducibility over time was fairly high for the three pathways, with ICCs ranging from 0.52 (16-hydroxylation pathway) to 0.72 (2-hydroxylation pathway). ICCs were similarly high for 2-catechols and the individual catechols (ICCs = 0.58-0.72). Individual and grouped methylated 2-catechols had fairly high ICCs (0.51-0.62), but methylated 4-catechols had low ICCs (0.14-0.27). These data indicate that, in general, urinary EM levels vary substantially among individuals compared with intraindiviual variability. Within-person reproducibility over time for most EM measures is comparable to or better than that for well-vetted biomarkers such as plasma cholesterol and, in postmenopausal women, estradiol.(Cancer Epidemiol Biomarkers Prev 2009;18(11):OF1-9).

Although androgens may play an etiologic role in breast, ovarian, and endometrial cancers, little is known about factors that influence circulating androgen levels. We conducted a cross-sectional analysis among 646 postmenopausal women in the Nurses' Health Study to examine associations between adult risk factors for cancer, including the Rosner/Colditz breast cancer risk score, and plasma levels of testosterone, free testosterone, androstenedione, dehydroepiandrosterone (DHEA), and DHEA sulfate (DHEAS). All analyses were adjusted for age, laboratory batch, and other cancer risk factors. Free testosterone levels were 79% higher among women with a BMI of >/=30 vs.<22 kg/m(2)(p-trend<0.01) and 25% higher among women with a waist circumference of >89 vs.</=74 cm (p-trend=0.02). Consuming >30 grams of alcohol a day vs. none was associated with a 31% increase in DHEA and 59% increase in DHEAS levels (p-trend=0.01 and <0.01, respectively). Smokers of >/=25 cigarettes per day had 35% higher androstenedione and 44% higher testosterone levels than never smokers (p-value, F-test=0.03 and 0.01, respectively). No significant associations were observed for height or time since menopause with any androgen. Testosterone and free testosterone levels were approximately 30% lower among women with a hysterectomy vs. without (both p-values<0.01). Overall breast cancer risk was not associated with any of the androgens. Thus, several risk factors, including body size, alcohol intake, smoking, and hysterectomy, were related to androgen levels among postmenopausal women, while others, including height and time since menopause, were not. Future studies are needed to clarify further which lifestyle factors modulate androgen levels.(c) 2009 UICC.

BACKGROUND: Circulating estrogens and androgens are important factors in the development of various female cancers. Caffeine intake may decrease risk of breast and ovarian cancer, although the data are not entirely consistent. Whether or not caffeine affects cancer risk by altering sex hormone levels is currently unknown. METHODS: We examined the relationship of caffeine, coffee, decaffeinated coffee, and tea with plasma concentrations of estrogens, androgens, progesterone, prolactin, and sex hormone-binding globulin (SHBG) in 524 premenopausal and 713 postmenopausal women from the Nurses' Health Study (NHS) and NHSII. RESULTS: In premenopausal women, caffeine intake was inversely associated with luteal total and free estradiol, and positively associated with luteal progesterone levels (P-trend =.02,.01,.03, respectively). Coffee intake was significantly associated with lower luteal total and free estradiol levels, but not luteal progesterone levels (P-trend =.007,.004,.20, respectively). Among the postmenopausal women, there was a positive association between caffeine and coffee intake and SHBG levels (P-trend =.03 and .06, respectively). No significant associations were detected with the other hormones. CONCLUSIONS: Data from this cross-sectional study suggest that caffeine may alter circulating levels of luteal estrogens and SHBG, representing possible mechanisms by which coffee or caffeine may be associated with pre- and postmenopausal malignancies, respectively. Future studies evaluating how caffeine-mediated alterations in sex hormones and binding protein levels affect the risk of female cancers are warranted.