Menopausal hormone therapy and lung cancer-specific mortality following diagnosis: the California Teachers Study.

Previous results from research on menopausal hormone therapy (MHT) and lung cancer survival have been mixed and most have not studied women who used estrogen therapy (ET) exclusively. We examined the associations between MHT use reported at baseline and lung cancer-specific mortality in the prospective California Teachers Study cohort. Among 727 postmenopausal women diagnosed with lung cancer from 1995 through 2007, 441 women died before January 1, 2008. Hazard Ratios (HR) and 95% Confidence Intervals (CI) for lung-cancer-specific mortality were obtained by fitting multivariable Cox proportional hazards regression models using age in days as the timescale. Among women who used ET exclusively, decreases in lung cancer mortality were observed (HR, 0.69; 95% CI, 0.52-0.93). No association was observed for estrogen plus progestin therapy use. Among former users, shorter duration (<5 years) of exclusive ET use was associated with a decreased risk of lung cancer mortality (HR, 0.56; 95% CI, 0.35-0.89), whereas among recent users, longer duration (>15 years) was associated with a decreased risk (HR, 0.60; 95% CI, 0.38-0.95). Smoking status modified the associations with deceases in lung cancer mortality observed only among current smokers. Exclusive ET use was associated with decreased lung cancer mortality.

Reproductive factors, exogenous hormones, and pancreatic cancer risk in the CTS.

Female steroid hormones are hypothesized to play a protective role in pancreatic cancer risk. However, results from epidemiologic studies that examined hormone-related exposures have been inconsistent. The California Teachers Study is a cohort study of female public school professionals that was established in 1995-1996. Of the 118,164 eligible study participants, 323 women were diagnosed with incident invasive pancreatic cancer through December 31, 2009. Multivariable Cox proportional hazards regression methods were used to estimate hazard ratios and 95% confidence intervals for the association of pancreatic cancer risk with reproductive factors and exogenous hormone use. Current users of estrogen-only therapy at baseline (1995-1996) had a lower risk of pancreatic cancer than did participants who had never used hormone therapy (hazard ratio = 0.59, 95% confidence interval: 0.42, 0.84). Use of estrogen-plus-progestin therapy was not associated with the risk of pancreatic cancer. A longer duration of oral contraceptive use (≥10 years of use compared with never use) was associated with an increased risk of cancer (hazard ratio = 1.72, 95% confidence interval: 1.19, 2.49). Reproductive factors, including age at menarche, parity, breastfeeding, and age at menopause, were not associated with pancreatic cancer risk. Our results suggest that increased estrogen exposure through estrogen-only therapy may reduce pancreatic cancer risk in women.

Increased long-term recreational physical activity is associated with older age at natural menopause among heavy smokers: the California Teachers Study.

OBJECTIVE: Although physical activity modulates the hypothalamic-pituitary-ovarian axis, the few studies that have investigated whether physical activity is associated with age at natural menopause have yielded mixed results. We set out to determine whether physical activity is associated with the timing of natural menopause in a large cohort of California women overall and by smoking history. METHODS: We investigated the association between long-term physical activity (h/wk/y) and age at natural menopause among 97,945 women in the California Teachers Study. Multivariable Cox proportional hazards regression methods were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). The impact of cigarette smoking (never smoker, former light smoker, former heavy smoker, current light smoker, and current heavy smoker) as an effect modifier was evaluated. RESULTS: In a multivariable model adjusted for body mass index at age 18 years, age at menarche, race/ethnicity, and age at first full-term pregnancy, increased physical activity was statistically significantly associated with older age at natural menopause (P(trend) = 0.005). Higher body mass index at age 18 years (P(trend) = 0.0003) and older age at menarche (P(trend) = 0.0003) were also associated with older age at natural menopause. Hispanic ethnicity (vs non-Hispanic whites; HR, 1.17; 95% CI, 1.09-1.26), current smokers (vs never smokers; HR, 1.68; 95% CI, 1.60-1.75 for current light smokers; HR, 1.38; 95% CI, 1.33-1.44 for current heavy smokers), and older age at first full-term pregnancy (HR(≥29, 2+ full-term pregnancies) vs HR(<29, 2+ full-term pregnancies), 1.10; 95% CI, 1.06-1.14) were associated with earlier age at natural menopause. Upon stratification by smoking history, increased physical activity was statistically significantly associated with older age at natural menopause among heavy smokers only (HR(highest quartile) vs HR(lowest quartile), 0.88; 95% CI, 0.81-0.97; P(trend) = 0.02 for former heavy smokers; HR(highest quartile) vs HR(lowest quartile), 0.89; 95% CI, 0.80-0.99; P(trend) = 0.04 for current heavy smokers). CONCLUSIONS: Age at natural menopause is a complex trait; the determinants of age at natural menopause, including physical activity, may differ by smoking status.

Absence of functional LIN28B mutations in a large cohort of patients with idiopathic central precocious puberty.

AIM: To investigate LIN28B gene variants in children with idiopathic central precocious puberty (CPP). PATIENTS AND METHODS: We studied 178 Brazilian children with CPP (171 girls, 16.8% familial cases). A large multiethnic group (1,599 subjects; Multiethnic Cohort, MEC) was used as control. DNA analysis and biochemical in vitro studies were performed. RESULTS: A heterozygous LIN28B variant, p.H199R, was identified in a girl who developed CPP at 5.2 years. This variant was absent in 310 Brazilian control individuals, but it was found in the same allele frequency in women from the MEC cohort, independent of the age of menarche. Functional studies revealed that when ectopically expressed in cells, the mutant protein was capable of binding pre-let-7 microRNA and inhibiting let-7 expression to the same extent as wild-type Lin28B protein. Other rare LIN28B variants (p.P173P, c.198+ 32_33delCT, g.9575731A>C and c.-11C>T) were identified in CPP patients and controls. Therefore, no functional mutation was identified. CONCLUSION: In vitro studies revealed that the rare LIN28B p.H199R variant identified in a girl with CPP does not affect the Lin28B function in the regulation of let-7 expression. Although LIN28B SNPs were associated with normal pubertal timing, rare variations in this gene do not seem to be commonly involved in the molecular pathogenesis of CPP.

Bilateral oophorectomy is not associated with increased mortality: the California Teachers Study.

OBJECTIVE: To investigate the effect of surgical menopause due to bilateral oophorectomy on mortality, in light of evidence that bilateral oophorectomy among premenopausal women rapidly reduces endogenous hormone levels, thereby modifying risks of cardiovascular disease and breast cancer. DESIGN: The California Teachers Study (CTS) is a prospective cohort study of 133,479 women initiated in 1995-1996 through a mailed, self-administered questionnaire. Relative risks and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression. SETTING: None. PATIENT(S): California Teachers Study participants who, at baseline, reported having surgical menopause due to bilateral oophorectomy (n = 9,785), were compared with participants with natural menopause (n = 32,219). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): We investigated whether bilateral oophorectomy was associated with all-cause, cardiovascular, or cancer mortality, overall and by menopausal hormone therapy use status. RESULT(S): Among participants aged <45 years at menopause, multivariable relative risks were 0.86 (95% CI, 0.74-1.00), 0.85 (95% CI, 0.66-1.11), and 0.91 (95% CI, 0.67-1.23) for all-cause mortality, cardiovascular mortality, and cancer mortality, respectively. Among participants with an age at menopause of ≥45 years, multivariable relative risks were 0.87 (95% CI, 0.80-0.94), 0.83 (95% CI, 0.71-0.96), and 0.84 (95% CI, 0.72-0.98) for all-cause, cardiovascular, and cancer mortality, respectively. The association between bilateral oophorectomy and mortality did not differ by baseline status of hormone therapy use. CONCLUSION(S): Surgical menopause due to bilateral oophorectomy vs. natural menopause does not increase all-cause, cardiovascular, or cancer mortality.

Oral contraceptive use and survival in women with invasive breast cancer.

BACKGROUND: Oral contraceptives (OC) are widely used in the United States. Although the relation between OC use and breast cancer incidence has been widely studied, the few studies examining associations between OC use prior to breast cancer diagnosis and survival are inconsistent. METHODS: Women with invasive breast cancer participating in the Women's Contraceptive and Reproductive Experiences (CARE) Study, a population-based case-control study (4565 women ages 35-64 years), and the California Teachers Study (CTS) cohort (3929 women ages 28-91 years) were followed for vital status. A total of 1,064 women died in the CARE Study (median follow-up, 8.6 years) and 523 died in the CTS (median follow-up, 6.1 years). Cox proportional hazards regression provided hazard rate ratio estimates [(relative risk, RR)] with 95% confidence intervals (CIs) for risk of death from any cause and from breast cancer. RESULTS: No association was observed for any OC use prior to diagnosis and all-cause mortality [CARE Study: RR = 1.01 (95% CI = 0.86-1.19); CTS: RR = 0.84 (95% CI = 0.67-1.05)]. A decreased risk of all-cause mortality was observed in the CTS among women with more than 10 years of OC use (RR = 0.67, 95% CI = 0.47-0.96); however, no trend of decreasing risk with increasing OC duration was observed (P(trend) = 0.22), and no association was observed in the CARE study. No associations were observed for breast cancer-specific mortality. CONCLUSIONS: OC use is not associated with all-cause or breast cancer-specific mortality among women with invasive breast cancer. IMPACT: These 2 independent studies demonstrated no overall association between OC use and survival among women with breast cancer.

Lower risk in parous women suggests that hormonal factors are important in bladder cancer etiology.

BACKGROUND: Urinary bladder cancer is two to four times more common among men than among women, a difference in risk not fully explained by established risk factors. Our objective was to determine whether hormonal and reproductive factors are involved in female bladder cancer. METHODS: We analyzed data from two population-based studies: the Los Angeles-Shanghai Bladder Cancer Study, with 349 female case-control pairs enrolled in Los Angeles and 131 female cases and 138 frequency-matched controls enrolled in Shanghai, and the California Teachers Study (CTS), a cohort of 120,857 women with 196 incident cases of bladder urothelial carcinoma diagnosed between 1995 and 2005. We also conducted a meta-analysis summarizing associations from our primary analyses together with published results. RESULTS: In primary data analyses, parous women experienced at least 30% reduced risk of developing bladder cancer compared with nulliparous women (Shanghai: OR = 0.38, 95% CI: 0.13-1.10; CTS: RR = 0.69, 95% CI: 0.50-0.95) consistent with results of a meta-analysis of nine studies (summary RR = 0.73, 95% CI: 0.63-0.85). The CTS, which queried formulation of menopausal hormone therapy (HT), revealed a protective effect for use of combined estrogen and progestin compared with no HT (RR = 0.60, 95% CI: 0.37-0.98). Meta-analysis of three studies provided a similar effect estimate (summary RR = 0.65, 95% CI: 0.48-0.88). CONCLUSIONS: A consistent pattern of reduced bladder cancer risk was found among parous women and those who used estrogen and progestin for HT. IMPACT: These results suggest that more research is warranted to investigate hormonal and reproductive factors as possible contributors to bladder cancer risk.

The association of polymorphisms in hormone metabolism pathway genes, menopausal hormone therapy, and breast cancer risk: a nested case-control study in the California Teachers Study cohort.

INTRODUCTION: The female sex steroids estrogen and progesterone are important in breast cancer etiology. It therefore seems plausible that variation in genes involved in metabolism of these hormones may affect breast cancer risk, and that these associations may vary depending on menopausal status and use of hormone therapy. METHODS: We conducted a nested case-control study of breast cancer in the California Teachers Study cohort. We analyzed 317 tagging single nucleotide polymorphisms (SNPs) in 24 hormone pathway genes in 2746 non-Hispanic white women: 1351 cases and 1395 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by fitting conditional logistic regression models using all women or subgroups of women defined by menopausal status and hormone therapy use. P values were adjusted for multiple correlated tests (PACT). RESULTS: The strongest associations were observed for SNPs in SLCO1B1, a solute carrier organic anion transporter gene, which transports estradiol-17ß-glucuronide and estrone-3-sulfate from the blood into hepatocytes. Ten of 38 tagging SNPs of SLCO1B1 showed significant associations with postmenopausal breast cancer risk; 5 SNPs (rs11045777, rs11045773, rs16923519, rs4149057, rs11045884) remained statistically significant after adjusting for multiple testing within this gene (PACT = 0.019-0.046). In postmenopausal women who were using combined estrogen-progestin therapy (EPT) at cohort enrollment, the OR of breast cancer was 2.31 (95% CI = 1.47-3.62) per minor allele of rs4149013 in SLCO1B1 (P = 0.0003; within-gene PACT = 0.002; overall PACT = 0.023). SNPs in other hormone pathway genes evaluated in this study were not associated with breast cancer risk in premenopausal or postmenopausal women. CONCLUSIONS: We found evidence that genetic variation in SLCO1B1 is associated with breast cancer risk in postmenopausal women, particularly among those using EPT.

The efficacy of detecting variants with small effects on the Affymetrix 6.0 platform using pooled DNA.

Genome-wide genotyping of a cohort using pools rather than individual samples has long been proposed as a cost-saving alternative for performing genome-wide association (GWA) studies. However, successful disease gene mapping using pooled genotyping has thus far been limited to detecting common variants with large effect sizes, which tend not to exist for many complex common diseases or traits. Therefore, for DNA pooling to be a viable strategy for conducting GWA studies, it is important to determine whether commonly used genome-wide SNP array platforms such as the Affymetrix 6.0 array can reliably detect common variants of small effect sizes using pooled DNA. Taking obesity and age at menarche as examples of human complex traits, we assessed the feasibility of genome-wide genotyping of pooled DNA as a single-stage design for phenotype association. By individually genotyping the top associations identified by pooling, we obtained a 14- to 16-fold enrichment of SNPs nominally associated with the phenotype, but we likely missed the top true associations. In addition, we assessed whether genotyping pooled DNA can serve as an inexpensive screen as the second stage of a multi-stage design with a large number of samples by comparing the most cost-effective 3-stage designs with 80% power to detect common variants with genotypic relative risk of 1.1, with and without pooling. Given the current state of the specific technology we employed and the associated genotyping costs, we showed through simulation that a design involving pooling would be 1.07 times more expensive than a design without pooling. Thus, while a significant amount of information exists within the data from pooled DNA, our analysis does not support genotyping pooled DNA as a means to efficiently identify common variants contributing small effects to phenotypes of interest. While our conclusions were based on the specific technology and study design we employed, the approach presented here will be useful for evaluating the utility of other or future genome-wide genotyping platforms in pooled DNA studies.

The association of body mass index with mortality in the California Teachers Study.

Although underweight and obesity have been associated with increased risk of mortality, it remains unclear whether the associations differ by hormone therapy (HT) use and smoking. The authors examined the relationship between body mass index (BMI) and mortality within the California Teachers Study (CTS), specifically considering the impact of HT and smoking. The authors examined the associations of underweight and obesity with risks of all-cause and cause-specific mortality, among 115,433 women participating in the CTS, and specifically examined whether HT use or smoking modifies the effects of obesity. Multivariable Cox proportional hazards regression provided estimates of relative risks (RRs) and 95% confidence intervals (CIs). During follow up, 10,574 deaths occurred. All-cause mortality was increased for underweight (BMI <18.5; adjusted RR = 1.33, 95% CI = 1.20-1.47) and obese participants (BMI ≥ 30: RR = 1.27, 95% CI = 1.19-1.37) relative to BMI of 18.5-24.9). Respiratory disease mortality was increased for underweight and obese participants. Death from any cancer, and breast cancer specifically, and cardiovascular disease was observed only for obese participants. The obesity and mortality association remained after stratification on HT and smoking. Obese participants remained at greater risk for mortality after stratification on menopausal HT and smoking. Obesity was associated with increased all-cause mortality, as well as death from any cancer (including breast), and cardiovascular and respiratory diseases. These findings help to identify groups at risk for BMI-related poor health outcomes.

Menopausal hormone therapy does not influence lung cancer risk: results from the California Teachers Study.

BACKGROUND: Results from studies examining the association between hormone therapy (HT) and lung cancer risk disagree. METHODS: We examined the associations between HT use and lung cancer risk among 60,592 postmenopausal women enrolled in the prospective California Teachers Study cohort. Between 1995 and 2007, a total of 727 women had a diagnosis of lung cancer. Multivariable Cox proportional hazards regression models were fit using age as the time metric. RESULTS: No measure of HT use was associated with lung cancer risk (all P(trend) values ≥0.4). In addition, no variations in risk by smoking status (never, ever, former, current), type of HT [estrogen (E)-alone, E + progestin (P) use], type of menopause, or lung cancer histology were observed. CONCLUSIONS: Our findings do not support an association between HT and lung cancer. IMPACT: This large-scale, prospective study, which capitalizes on the detailed hormone use, smoking history, and type of menopause information available within this unique cohort, was unable to find any association between intake of HT and lung cancer risk.

Oral contraceptives, menopausal hormone therapy use and risk of B-cell non-Hodgkin lymphoma in the California Teachers Study.

We examined oral contraceptive (OC) and menopausal hormonal therapy (MHT) use in relation to risk of B-cell non-Hodgkin lymphoma (NHL). Women under age 85 years participating in the California Teachers Study with no history of hematopoietic cancer were followed from 1995 through 2007. A total of 516 of 114,131 women eligible for OC use analysis and 402 of 54,758 postmenopausal women eligible for MHT use analysis developed B-cell NHL. Multivariable adjusted and age stratified Cox proportional hazards models were fit to estimate relative risks (RRs) and 95% confidence intervals (95% CI). Ever versus never OC use was marginally associated with lower B-cell NHL risk, particularly among women first using OCs before age 25 years (RR=0.72, 95% CI=0.51-0.99); yet, no duration-response effect was observed. No association was observed for ever versus never MHT use among postmenopausal women (RR=1.05, 95% CI=0.83-1.33) overall or by formulation (estrogen alone, ET, or estrogen plus progestin, EPT). Among women with no MHT use, having bilateral oophorectomy plus hysterectomy was associated with greater B-cell NHL risk than having natural menopause (RR=3.15, 95% CI=1.62-6.13). Bilateral oophorectomy plus hysterectomy was not associated with risk among women who used ET or EPT. These results indicate that exogenous hormone use does not strongly influence B-cell NHL risk.

Age-specific effects of hormone therapy use on overall mortality and ischemic heart disease mortality among women in the California Teachers Study.

OBJECTIVE: Although the Women's Health Initiative trial suggested that menopausal hormone therapy (HT) does not reduce coronary heart disease mortality overall, subsequent results have suggested that there may be a benefit in younger women. The California Teachers Study questionnaire and mortality data were used to examine whether age modified the association between HT and the relative risk of overall mortality and ischemic heart disease deaths. METHODS: Participants from the California Teachers Study were 71,237 postmenopausal women (mean age, 63 y; range, 36-94 y) followed prospectively for mortality and other outcomes from 1995-1996 through 2004. RESULTS: Age at baseline was a much more important modifier of HT effects than was age at start of therapy. Risks for all-cause mortality (n = 8,399) were lower for younger current HT users at baseline than for never users (for women ≤ 0 y: hazard ratio, 0.54; 95% CI, 0.46-0.62). These risk reductions greatly diminished, in a roughly linear fashion, with increasing baseline age (for women 85-94 y: hazard ratio, 0.94; 95% CI, 0.81-1.10 for all-cause mortality). Similar results were seen for ischemic heart disease deaths (n = 1,464). No additional significant modifying effects of age at first use, duration of use, or formulation were apparent. CONCLUSIONS: These results provide evidence that reduced risks of mortality associated with HT use are observed among younger users but not for older postmenopausal women, even those starting therapy close to their time of menopause.

Associations of insulin resistance and adiponectin with mortality in women with breast cancer.

PURPOSE: Overweight or obese breast cancer patients have a worse prognosis compared with normal-weight patients. This may be attributed to hyperinsulinemia and dysregulation of adipokine levels associated with overweight and obesity. Here, we evaluate whether low levels of adiponectin and a greater level of insulin resistance are associated with breast cancer mortality and all-cause mortality. PATIENTS AND METHODS: We measured glucose, insulin, and adiponectin levels in fasting serum samples from 527 women enrolled in the Health, Eating, Activity, and Lifestyle (HEAL) Study, a multiethnic, prospective cohort study of women diagnosed with stage I-IIIA breast cancer. We evaluated the association between adiponectin and insulin and glucose levels (expressed as the Homeostatic Model Assessment [HOMA] score) represented as continuous measures and median split categories, along with breast cancer mortality and all-cause mortality, using Cox proportional hazards models. RESULTS: Increasing HOMA scores were associated with reduced breast cancer survival (hazard ratio [HR], 1.12; 95% CI, 1.05 to 1.20) and reduced all-cause survival (HR, 1.09; 95% CI, 1.02 to 1.15) after adjustment for possible confounders. Higher levels of adiponectin (above the median: 15.5 µg/mL) were associated with longer breast cancer survival (HR, 0.39; 95% CI, 0.15 to 0.95) after adjustment for covariates. A continuous measure of adiponectin was not associated with either breast cancer-specific or all-cause mortality. CONCLUSION: Elevated HOMA scores and low levels of adiponectin, both associated with obesity, were associated with increased breast cancer mortality. To the best of our knowledge, this is the first demonstration of the association between low levels of adiponectin and increased breast cancer mortality in breast cancer survivors.

Body-mass index and mortality among 1.46 million white adults.

BACKGROUND: A high body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) is associated with increased mortality from cardiovascular disease and certain cancers, but the precise relationship between BMI and all-cause mortality remains uncertain. METHODS: We used Cox regression to estimate hazard ratios and 95% confidence intervals for an association between BMI and all-cause mortality, adjusting for age, study, physical activity, alcohol consumption, education, and marital status in pooled data from 19 prospective studies encompassing 1.46 million white adults, 19 to 84 years of age (median, 58). RESULTS: The median baseline BMI was 26.2. During a median follow-up period of 10 years (range, 5 to 28), 160,087 deaths were identified. Among healthy participants who never smoked, there was a J-shaped relationship between BMI and all-cause mortality. With a BMI of 22.5 to 24.9 as the reference category, hazard ratios among women were 1.47 (95 percent confidence interval [CI], 1.33 to 1.62) for a BMI of 15.0 to 18.4; 1.14 (95% CI, 1.07 to 1.22) for a BMI of 18.5 to 19.9; 1.00 (95% CI, 0.96 to 1.04) for a BMI of 20.0 to 22.4; 1.13 (95% CI, 1.09 to 1.17) for a BMI of 25.0 to 29.9; 1.44 (95% CI, 1.38 to 1.50) for a BMI of 30.0 to 34.9; 1.88 (95% CI, 1.77 to 2.00) for a BMI of 35.0 to 39.9; and 2.51 (95% CI, 2.30 to 2.73) for a BMI of 40.0 to 49.9. In general, the hazard ratios for the men were similar. Hazard ratios for a BMI below 20.0 were attenuated with longer-term follow-up. CONCLUSIONS: In white adults, overweight and obesity (and possibly underweight) are associated with increased all-cause mortality. All-cause mortality is generally lowest with a BMI of 20.0 to 24.9.

Body size and the risk of ovarian cancer by hormone therapy use in the California Teachers Study cohort.

OBJECTIVE: To investigate whether obesity and hormone therapy (HT) are associated with ovarian cancer risk among women in the California Teachers Study cohort. METHODS: Of 56,091 women age ≥ 45 years, 277 developed epithelial ovarian cancer between 1995 and 2007. Multivariate Cox regression was performed. RESULTS: Among women who never used HT, greater adult weight gain, waist circumference and waist-to-height ratio, but not adult BMI, increased risk of ovarian cancer. Compared to women who never used HT and had a stable adult weight, risk of ovarian cancer was increased in women who gained ≥ 40 lb (relative risk (RR) 1.8, 95% confidence interval (CI): 1.0-3.0) or used HT for >5 years (RR 2.3 95% CI: 1.3-4.1). Having both exposures (RR 1.9, 95% CI: 0.99-3.5), however, did not increase risk more than having either alone. Results were similar for waist circumference and weight-to-height ratio; however, differences across HT groups were not statistically significant. CONCLUSIONS: This study suggests that abdominal adiposity and weight gain, but not overall obesity, increase ovarian cancer risk and that there may be a threshold level beyond which additional hormones, whether exogenous or endogenous, do not result in additional elevation in risk. However, large pooled analyses are needed to confirm these findings.

Menopausal hormone therapy and subsequent risk of specific invasive breast cancer subtypes in the California Teachers Study.

BACKGROUND: Although it is well established that combined estrogen-progestin therapy (EPT) increases breast cancer risk, questions remain regarding the effect of different formulations of hormones, whether certain women are at particularly high risk, and whether risk varies by tumor subtype. METHODS: We investigated hormone therapy (HT) use in relation to breast cancer risk in the California Teachers Study cohort; after a mean follow-up of 9.8 years, 2,857 invasive breast cancers were diagnosed. RESULTS: Compared with women who had never used HT, women who reported 15 or more years of estrogen therapy (ET) use had a 19% greater risk of breast cancer (95% confidence interval, 1.03-1.37), whereas women using EPT for 15 or more years had an 83% greater risk (95% confidence interval, 1.48-2.26). Breast cancer risk was highest among women using continuous combined EPT regimens. Risks associated with EPT and ET use were increased with duration of HT use for women with a body mass index (BMI) of <29.9 kg/m(2) but not for women with BMI of >or=30 kg/m(2). Elevated risks associated with EPT and ET use were confined to tumors that were positive for both estrogen and progesterone receptors and those that were HER2+ but were slightly diminished for HER2- tumors. CONCLUSIONS: Breast cancer risks increased with longer duration of ET and EPT use, and risks were highest for continuous-combined EPT use. Furthermore, risks varied by BMI and tumor subtype. IMPACT: These findings underscore the need for personalized risk-benefit discussions with women contemplating HT use.

Pregnancy-related factors and the risk of breast carcinoma in situ and invasive breast cancer among postmenopausal women in the California Teachers Study cohort.

INTRODUCTION: Although pregnancy-related factors such as nulliparity and late age at first full-term pregnancy are well-established risk factors for invasive breast cancer, the roles of these factors in the natural history of breast cancer development remain unclear. METHODS: Among 52,464 postmenopausal women participating in the California Teachers Study (CTS), 624 were diagnosed with breast carcinoma in situ (CIS) and 2,828 with invasive breast cancer between 1995 and 2007. Multivariable Cox proportional hazards regression methods were used to estimate relative risks associated with parity, age at first full-term pregnancy, breastfeeding, nausea or vomiting during pregnancy, and preeclampsia. RESULTS: Compared with never-pregnant women, an increasing number of full-term pregnancies was associated with greater risk reduction for both breast CIS and invasive breast cancer (both P trend < 0.01). Women having four or more full-term pregnancies had a 31% lower breast CIS risk (RR = 0.69, 95% CI = 0.51 to 0.93) and 18% lower invasive breast cancer risk (RR = 0.82, 95% CI = 0.72 to 0.94). Parous women whose first full-term pregnancy occurred at age 35 years or later had a 118% greater risk for breast CIS (RR = 2.18, 95% CI = 1.36 to 3.49) and 27% greater risk for invasive breast cancer (RR = 1.27, 95% CI = 0.99 to 1.65) than those whose first full-term pregnancy occurred before age 21 years. Furthermore, parity was negatively associated with the risk of estrogen receptor-positive (ER+) or ER+/progesterone receptor-positive (PR+) while age at first full-term pregnancy was positively associated with the risk of ER+ or ER+/PR+ invasive breast cancer. Neither of these factors was statistically significantly associated with the risk of ER-negative (ER-) or ER-/PR- invasive breast cancer, tests for heterogeneity between subtypes did not reach statistical significance. No clear associations were detected for other pregnancy-related factors. CONCLUSIONS: These results provide some epidemiologic evidence that parity and age at first full-term pregnancy are involved in the development of breast cancer among postmenopausal women. The role of these factors in risk of in situ versus invasive, and hormone receptor-positive versus -negative breast cancer merits further exploration.

Parents' ages at birth and risk of adult-onset hematologic malignancies among female teachers in California.

Although advanced parental age at one's birth has been associated with increased risk of breast and prostate cancers, few studies have examined its effect on adult-onset sporadic hematologic malignancies. The authors examined the association of parents' ages at women's births with risk of hematologic malignancies among 110,999 eligible women aged 22-84 years recruited into the prospective California Teachers Study. Between 1995 and 2007, 819 women without a family history of hematologic malignancies were diagnosed with incident lymphoma, leukemia (primarily acute myeloid leukemia), or multiple myeloma. Multivariable-adjusted Cox proportional hazards models provided estimates of relative risks and 95% confidence intervals. Paternal age was positively associated with non-Hodgkin lymphoma after adjustment for race and birth order (relative risk for age > or =40 vs. <25 years = 1.51, 95% confidence interval: 1.08, 2.13; P-trend = 0.01). Further adjustment for maternal age did not materially alter the association. By contrast, the elevated non-Hodgkin lymphoma risk associated with advanced maternal age (> or =40 years) became null when paternal age was included in the statistical model. No association was observed for acute myeloid leukemia or multiple myeloma. Advanced paternal age may play a role in non-Hodgkin lymphoma etiology. Potential etiologic mechanisms include de novo gene mutations, aberrant paternal gene imprinting, or telomere/telomerase biology.

Rapid assessment of genetic ancestry in populations of unknown origin by genome-wide genotyping of pooled samples.

As we move forward from the current generation of genome-wide association (GWA) studies, additional cohorts of different ancestries will be studied to increase power, fine map association signals, and generalize association results to additional populations. Knowledge of genetic ancestry as well as population substructure will become increasingly important for GWA studies in populations of unknown ancestry. Here we propose genotyping pooled DNA samples using genome-wide SNP arrays as a viable option to efficiently and inexpensively estimate admixture proportion and identify ancestry informative markers (AIMs) in populations of unknown origin. We constructed DNA pools from African American, Native Hawaiian, Latina, and Jamaican samples and genotyped them using the Affymetrix 6.0 array. Aided by individual genotype data from the African American cohort, we established quality control filters to remove poorly performing SNPs and estimated allele frequencies for the remaining SNPs in each panel. We then applied a regression-based method to estimate the proportion of admixture in each cohort using the allele frequencies estimated from pooling and populations from the International HapMap Consortium as reference panels, and identified AIMs unique to each population. In this study, we demonstrated that genotyping pooled DNA samples yields estimates of admixture proportion that are both consistent with our knowledge of population history and similar to those obtained by genotyping known AIMs. Furthermore, through validation by individual genotyping, we demonstrated that pooling is quite effective for identifying SNPs with large allele frequency differences (i.e., AIMs) and that these AIMs are able to differentiate two closely related populations (HapMap JPT and CHB).