Variants in hormone biosynthesis genes and risk of endometrial cancer. Cancer Causes Control. 2008;19:955-963. [PMID: 18437511 DOI: 10.1007/s10552-008-9160-7]

<sc>d</sc>-Chiro-Inositol in Clinical Practice: A Perspective from the Experts Group on Inositol in Basic and Clinical Research (EGOI)

BACKGROUND

d-Chiro-inositol is a natural molecule that, in association with its well-studied isomer myo-inositol, may play a role in treating various metabolic and gynecological disorders.

OBJECTIVES

This perspective seeks to explore the mechanisms and functions of d-chiro-inositol, laying the foundations to discuss its use in clinical practice, across dysmetabolism, obesity, and hormonal dysregulation.

METHODS

A narrative review of all the relevant papers known to the authors was conducted.

OUTCOME

d-Chiro-inositol acts through a variety of mechanisms, acting as an insulin sensitizer, inhibiting the transcription of aromatase, in addition to modulating white adipose tissue/brown adipose tissue transdifferentiation. These different modes of action have potential applications in a variety of therapeutic fields, including PCOS, dysmetabolism, obesity, hypoestrogenic/hyperandrogenic disorders, and bone health.

CONCLUSIONS

d-Chiro-inositol mode of action has been studied in detail in recent years, resulting in a clear differentiation between d-chiro-inositol and its isomer myo-inositol. The insulin-sensitizing activities of d-chiro-inositol are well understood; however, its potential applications in other fields, in particular obesity and hyperestrogenic/hypoandrogenic disorders in men and women, represent promising avenues of research that require further clinical study.

Risk factors for endometrial cancer in Black women

PURPOSE

The incidence of endometrial cancer (EC) has been increasing faster among Black women than among other racial/ethnic groups in the United States. Although the mortality rate is nearly twice as high among Black than White women, there is a paucity of literature on risk factors for EC among Black women, particularly regarding menopausal hormone use and severe obesity.

METHODS

We pooled questionnaire data on 811 EC cases and 3,124 controls from eight studies with data on self-identified Black women (4 case-control and 4 cohort studies). We analyzed cohort studies as nested case-control studies with up to 4 controls selected per case. We used logistic regression to estimate multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

We observed a positive association between BMI and EC incidence (P_trend < 0.0001) The OR comparing BMI ≥ 40 vs. < 25 kg/m² was 3.92 (95% CI 2.91, 5.27). Abdominal obesity among those with BMI < 30 kg/m² was not appreciably associated with EC risk (OR 1.21, 95% CI 0.74, 1.99). Associations of reproductive history with EC were similar to those observed in studies of White women. Long-term use of estrogen-only menopausal hormones was associated with an increased risk of EC (≥ 5 years vs. never use: OR 2.08, 95% CI: 1.06, 4.06).

CONCLUSIONS

Our results suggest that the associations of established risk factors with EC are similar between Black and White women. Other explanations, such as differences in the prevalence of known risk factors or previously unidentified risk factors likely underlie the recent increases in EC incidence among Black women.

Pharmacogenomics variants are associated with BMI differences between individuals with bipolar and other psychiatric disorders

Aim: Regardless of the plethora of next-generation sequencing studies in the field of pharmacogenomics (PGx), the potential effect of covariate variables on PGx response within deeply phenotyped cohorts remains unexplored. Materials & methods: We explored with advanced statistical methods the potential influence of BMI, as a covariate variable, on PGx response in a Greek cohort with psychiatric disorders. Results: Nine PGx variants within UGT1A6, SLC22A4, GSTP1, CYP4B1, CES1, SLC29A3 and DPYD were associated with altered BMI in different psychiatric disorder groups. Carriers of rs2070959 (UGT1A6), rs199861210 (SLC29A3) and rs2297595 (DPYD) were also characterized by significant changes in the mean BMI, depending on the presence of psychiatric disorders. Conclusion: Specific PGx variants are significantly associated with BMI in a Greek cohort with psychiatric disorders.

Analysis of 12 variants in the development of gastric and colorectal cancers

AIM

To evaluate the relation between 12 polymorphisms and the development of gastric cancer (GC) and colorectal cancer (CRC).

METHODS

In this study, we included 125 individuals with GC diagnosis, 66 individuals with CRC diagnosis and 475 cancer-free individuals. All participants resided in the North region of Brazil and authorized the use of their samples. The 12 polymorphisms (in CASP8, CYP2E1, CYP19A1, IL1A, IL4, MDM2, NFKB1, PAR1, TP53, TYMS, UGT1A1 and XRCC1 genes) were genotyped in a single PCR for each individual, followed by fragment analysis. To avoid misinterpretation due to population substructure, we applied a previously developed set of 61 ancestry-informative markers that can also be genotyped by multiplex PCR. The statistical analyses were performed in Structure v.2.3.4, R environment and SPSS v.20.

RESULTS

After statistical analyses with the control of confounding factors, such as genetic ancestry, three markers (rs79071878 in IL4, rs3730485 in MDM2 and rs28362491 in NFKB1) were positively associated with the development of GC. One of these markers (rs28362491) and the marker in the UGT1A1 gene (rs8175347) were positively associated with the development of CRC. Therefore, we investigated whether the joint presence of the deleterious alleles of each marker could affect the development of cancer and we obtained positive results in all analyses. Carriers of the combination of alleles RP1 + DEL (rs79071878 and rs28361491, respectively) are at 10-times greater risk of developing GC than carriers of other combinations. Similarly, carriers of the combination of DEL + RARE (rs283628 and rs8175347) are at about 12-times greater risk of developing CRC than carriers of other combinations.

CONCLUSION

These findings are important for the comprehension of gastric and CRC development, particularly in highly admixed populations, such as the Brazilian population.

Epidemiology of Endometrial Carcinoma: Etiologic Importance of Hormonal and Metabolic Influences

Endometrial carcinoma is the most common gynecologic cancer in developed nations, and the annual incidence is projected to increase, secondary to the high prevalence of obesity, a strong endometrial carcinoma risk factor. Although endometrial carcinomas are etiologically, biologically, and clinically diverse, hormonal and metabolic mechanisms are particularly strongly implicated in the pathogenesis of endometrioid carcinoma, the numerically predominant subtype. The centrality of hormonal and metabolic disturbances in the pathogenesis of endometrial carcinoma, combined with its slow development from well-characterized precursors in most cases, offers a substantial opportunity to reduce endometrial carcinoma mortality through early detection, lifestyle modification, and chemoprevention. In this chapter, we review the epidemiology of endometrial carcinoma, emphasizing theories that link risk factors for these tumors to hormonal and metabolic mechanisms. Future translational research opportunities related to prevention are discussed.

Body Mass Index Genetic Risk Score and Endometrial Cancer Risk

Genome-wide association studies (GWAS) have identified common variants that predispose individuals to a higher body mass index (BMI), an independent risk factor for endometrial cancer. Composite genotype risk scores (GRS) based on the joint effect of published BMI risk loci were used to explore whether endometrial cancer shares a genetic background with obesity. Genotype and risk factor data were available on 3,376 endometrial cancer case and 3,867 control participants of European ancestry from the Epidemiology of Endometrial Cancer Consortium GWAS. A BMI GRS was calculated by summing the number of BMI risk alleles at 97 independent loci. For exploratory analyses, additional GRSs were based on subsets of risk loci within putative etiologic BMI pathways. The BMI GRS was statistically significantly associated with endometrial cancer risk (P = 0.002). For every 10 BMI risk alleles a woman had a 13% increased endometrial cancer risk (95% CI: 4%, 22%). However, after adjusting for BMI, the BMI GRS was no longer associated with risk (per 10 BMI risk alleles OR = 0.99, 95% CI: 0.91, 1.07; P = 0.78). Heterogeneity by BMI did not reach statistical significance (P = 0.06), and no effect modification was noted by age, GWAS Stage, study design or between studies (P≥0.58). In exploratory analyses, the GRS defined by variants at loci containing monogenic obesity syndrome genes was associated with reduced endometrial cancer risk independent of BMI (per BMI risk allele OR = 0.92, 95% CI: 0.88, 0.96; P = 2.1 x 10⁻⁵). Possessing a large number of BMI risk alleles does not increase endometrial cancer risk above that conferred by excess body weight among women of European descent. Thus, the GRS based on all current established BMI loci does not provide added value independent of BMI. Future studies are required to validate the unexpected observed relation between monogenic obesity syndrome genetic variants and endometrial cancer risk.

A Single Nucleotide Polymorphism near the CYP17A1 Gene Is Associated with Left Ventricular Mass in Hypertensive Patients under Pharmacotherapy

Cytochrome P450 17A1 (CYP17A1) catalyses the formation and metabolism of steroid hormones. They are involved in blood pressure (BP) regulation and in the pathogenesis of left ventricular hypertrophy. Therefore, altered function of CYP17A1 due to genetic variants may influence BP and left ventricular mass. Notably, genome wide association studies supported the role of this enzyme in BP control. Against this background, we investigated associations between single nucleotide polymorphisms (SNPs) in or nearby the CYP17A1 gene with BP and left ventricular mass in patients with arterial hypertension and associated cardiovascular organ damage treated according to guidelines. Patients (n = 1007, mean age 58.0 ± 9.8 years, 83% men) with arterial hypertension and cardiac left ventricular ejection fraction (LVEF) ≥ 40% were enrolled in the study. Cardiac parameters of left ventricular mass, geometry and function were determined by echocardiography. The cohort comprised patients with coronary heart disease (n = 823; 81.7%) and myocardial infarction (n = 545; 54.1%) with a mean LVEF of 59.9% ± 9.3%. The mean left ventricular mass index (LVMI) was 52.1 ± 21.2 g/m2.7 and 485 (48.2%) patients had left ventricular hypertrophy. There was no significant association of any investigated SNP (rs619824, rs743572, rs1004467, rs11191548, rs17115100) with mean 24 h systolic or diastolic BP. However, carriers of the rs11191548 C allele demonstrated a 7% increase in LVMI (95% CI: 1%-12%, p = 0.017) compared to non-carriers. The CYP17A1 polymorphism rs11191548 demonstrated a significant association with LVMI in patients with arterial hypertension and preserved LVEF. Thus, CYP17A1 may contribute to cardiac hypertrophy in this clinical condition.

Intrauterine devices and endometrial cancer risk: a pooled analysis of the Epidemiology of Endometrial Cancer Consortium

Intrauterine devices (IUDs), long-acting and reversible contraceptives, induce a number of immunological and biochemical changes in the uterine environment that could affect endometrial cancer (EC) risk. We addressed this relationship through a pooled analysis of data collected in the Epidemiology of Endometrial Cancer Consortium. We combined individual-level data from 4 cohort and 14 case-control studies, in total 8,801 EC cases and 15,357 controls. Using multivariable logistic regression, we estimated pooled odds ratios (pooled-ORs) and 95% confidence intervals (CIs) for EC risk associated with ever use, type of device, ages at first and last use, duration of use and time since last use, stratified by study and adjusted for confounders. Ever use of IUDs was inversely related to EC risk (pooled-OR = 0.81, 95% CI = 0.74-0.90). Compared with never use, reduced risk of EC was observed for inert IUDs (pooled-OR = 0.69, 95% CI = 0.58-0.82), older age at first use (≥ 35 years pooled-OR = 0.53, 95% CI = 0.43-0.67), older age at last use (≥ 45 years pooled-OR = 0.60, 95% CI = 0.50-0.72), longer duration of use (≥ 10 years pooled-OR = 0.61, 95% CI = 0.52-0.71) and recent use (within 1 year of study entry pooled-OR = 0.39, 95% CI = 0.30-0.49). Future studies are needed to assess the respective roles of detection biases and biologic effects related to foreign body responses in the endometrium, heavier bleeding (and increased clearance of carcinogenic cells) and localized hormonal changes.

Consumption of sugary foods and drinks and risk of endometrial cancer

Consumption of foods high in sugar promotes insulin production, which has been linked to endometrial carcinogenesis. We evaluated the impact of dietary intake of sugary foods and beverages, as well as added sugar and total sugar on endometrial cancer risk in a population-based case-control study, including 424 cases and 398 controls. Participants completed an interview and food frequency questionnaire, and provided self-recorded waist and hip measurements. Women in the highest quartile of added sugar intake had significantly increased endometrial cancer risk (OR = 1.84, 95% CI 1.16-2.92). Among women with waist-to-hip ratio ≥0.85, risk was significantly higher for the highest versus lowest tertile of added sugar intakes (OR = 2.50, 95% CI 1.38-4.52). The association with added sugar also became stronger when analyses were restricted to never users of hormone replacement therapy (OR = 2.03; 95% CI 1.27-3.26, for highest versus lowest tertile). There was little evidence of effect modification by body mass index or physical activity. Given the high prevalence of intake of sugary foods and drinks in Western populations, additional research is warranted to confirm our findings on endometrial cancer.

Genetic variation of the CYP17 and susceptibility to endometrial cancer: a meta-analysis

Excessive estrogenic influence is known to be associated with initiation/promotion of endometrial cancer (EC). Common variants among genes coding for enzymes in sex steroid biosynthetic pathways may influence the risk of EC. Cytochrome P450c17α (CYP17), a gene that codes for a key enzyme (cytochrome P450c17α) in a rate-limiting step of estrogen biosynthesis has attracted considerable attention as a candidate gene for EC. The relationship between CYP17 and EC has been reported in various ethnic groups; however, these studies have yielded contradictory results. To investigate this inconsistency, we performed a meta-analysis of 13 studies involving a total of 3,258 cases and 4,614 controls for -34T>C (rs743572) polymorphism of the CYP17 gene to evaluate the effect of CYP17 on genetic susceptibility for EC. An overall random effects odds ratio of 0.71 (95% confidence interval 0.58-0.88, P=0.001) was found under recessive genetic model. Stratified analysis based on ethnicity, sample size and Hardy-Weinberg equilibrium status was conducted to explore potential heterogeneity. This meta-analysis demonstrated that the C allele of -34T>C in CYP17 is a protective factor associated with decreased EC susceptibility, but these associations vary in different ethnic populations.

CYP17A1 T-34C polymorphism is not associated with endometrial cancer risk

The association between CYP17A1 T-34C polymorphism and endometrial cancer risk has been inconsistent and underpowered. To clarify the effect of CYP17A1 T-34C polymorphism on the risk of endometrial cancer, a meta-analysis of all available studies relating CYP17A1 T-34C polymorphism to the risk of endometrial cancer was conducted. The authors searched PubMed, EMBASE, Scopus, and VisionCite databases updated on March 2013. Data were extracted by two independent authors and pooled odds ratio (OR) with 95 % confidence interval (CI) was calculated. Finally, seven studies with 1,570 endometrial cancer cases and 2,474 controls were included in the meta-analysis. There was no statistically significant association between CYP17A1 T-34C polymorphism and endometrial cancer under heterogeneous codominant model (OR = 0.91, 95 %CI = 0.68-1.21). Although CYP17A1 T-34C polymorphism was marginally associated with endometrial cancer risk under homogeneous codominant model (OR = 0.69, 95 %CI = 0.49-0.99), the significant association was not stable after sensitivity analysis. We concluded that CYP17A1 T-34C polymorphism might not be one risk factor in the carcinogenesis of endometrial cancer. Further large and well-designed studies are needed to confirm this association.

Age at last birth in relation to risk of endometrial cancer: pooled analysis in the epidemiology of endometrial cancer consortium

Childbearing at an older age has been associated with a lower risk of endometrial cancer, but whether the association is independent of the number of births or other factors remains unclear. Individual-level data from 4 cohort and 13 case-control studies in the Epidemiology of Endometrial Cancer Consortium were pooled. A total of 8,671 cases of endometrial cancer and 16,562 controls were included in the analysis. After adjustment for known risk factors, endometrial cancer risk declined with increasing age at last birth (P(trend) < 0.0001). The pooled odds ratio per 5-year increase in age at last birth was 0.87 (95% confidence interval: 0.85, 0.90). Women who last gave birth at 40 years of age or older had a 44% decreased risk compared with women who had their last birth under the age of 25 years (95% confidence interval: 47, 66). The protective association was similar across the different age-at-diagnosis groups and for the 2 major tumor histologic subtypes (type I and type II). No effect modification was observed by body mass index, parity, or exogenous hormone use. In this large pooled analysis, late age at last birth was independently associated with a reduced risk of endometrial cancer, and the reduced risk persisted for many years.

Phytoestrogen consumption from foods and supplements and epithelial ovarian cancer risk: a population-based case control study

Background

While there is extensive literature evaluating the impact of phytoestrogen consumption on breast cancer risk, its role on ovarian cancer has received little attention.

Methods

We conducted a population-based case-control study to evaluate phytoestrogen intake from foods and supplements and epithelial ovarian cancer risk. Cases were identified in six counties in New Jersey through the New Jersey State Cancer Registry. Controls were identified by random digit dialing, CMS (Centers for Medicare and Medicaid Service) lists, and area sampling. A total of 205 cases and 390 controls were included in analyses. Unconditional logistic regression analyses were conducted to examine associations with total phytoestrogens, as well as isoflavones (daidzein, genistein, formononetin, and glycitein), lignans (matairesinol, lariciresinol, pinoresinol, secoisolariciresinol), and coumestrol.

Results

No statistically significant associations were found with any of the phytoestrogens under evaluation. However, there was a suggestion of an inverse association with total phytoestrogen consumption (from foods and supplements), with an odds ratio (OR) of 0.62 (95% CI: 0.38-1.00; p for trend: 0.04) for the highest vs. lowest tertile of consumption, after adjusting for reproductive covariates, age, race, education, BMI, and total energy. Further adjustment for smoking and physical activity attenuated risk estimates (OR: 0.66; 95% CI: 0.41-1.08). There was little evidence of an inverse association for isoflavones, lignans, or coumestrol.

Conclusions

This study provided some suggestion that phytoestrogen consumption may decrease ovarian cancer risk, although results did not reach statistical significance.

Variations in sex hormone metabolism genes, postmenopausal hormone therapy and risk of endometrial cancer

We investigated whether variants in sex steroid hormone metabolism genes modify the effect of hormone therapy (HT) on endometrial cancer risk in postmenopausal non-Hispanic white women. A nested case-control study was conducted within the California Teachers Study (CTS). We genotyped htSNPs in six genes involved in the hormone metabolism in 286 endometrial cancer cases and 488 controls. Odds ratio (OR) and 95% confidence interval (CI) were estimated for each haplotype using unconditional logistic regression, adjusting for age. The strongest interaction was observed between duration of estrogen therapy (ET) use and haplotype 1A in CYP11A1 (p(interaction) = 0.0027; p(interaction) = 0.010 after correcting for multiple testing within each gene). The OR for endometrial cancer per copy of haplotype 1A was 2.00 (95% CI: 1.05-3.96) for long-term ET users and 0.90 (95% CI: 0.69-1.18) for never users. The most significant interaction with estrogen-progestin therapy (EPT) was found for two haplotypes on CYP19A1 and EPT use (haplotype 4A, p(interaction) = 0.024 and haplotype 3B, p(interaction) = 0.043). However, neither this interaction, nor the ET or EPT interactions for any other genes, was statistically significant after correction for multiple testing. Variations in CYP11A1 may modify the effect of ET use on risk of postmenopausal endometrial cancer; however, larger studies are needed to explore these findings further.

Healthy eating index and ovarian cancer risk

The evidence for a role of diet on ovarian cancer prevention remains inconclusive. While many studies have evaluated individual foods and food groups, the evaluation of a comprehensive dietary quality index for predicting cancer risk has received little attention. This study investigates the association between the Healthy Eating Index (HEI), which reflects adherence to the current USDA Dietary Guidelines for Americans and ovarian cancer risk in a population-based case-control study in New Jersey. A total of 205 cases and 390 controls completed the Block 98.2 food frequency questionnaire (FFQ) in addition to reporting on potential risk factors for ovarian cancer. FFQ data were then utilized to calculate the HEI score, and cup, ounce, gram, or caloric equivalents for the 12 different food groups comprising the index. In multivariate models, the OR for the highest tertile of the HEI score compared with the lowest (reflecting a better diet compared with a worse diet) was 0.90 (95% CI: 0.55-1.47). There was limited evidence for a statistically significant association between any of the 12 individual food components and ovarian cancer risk. Based on this study's results, neither individual food groups nor dietary quality showed potential for preventing ovarian cancer.

Cytochrome P450 17 (CYP17) is involved in endometrial cancinogenesis through apoptosis and invasion pathways

Cytochrome P450 17 (CYP17) encodes cytochrome P450c17α, an enzyme with 17α-hydroxylase and 17, 20-lyase activities involved in estradiol biosynthesis. Here we examine the role of CYP17 gene in endometrial carcinogenesis. Immunohistochemistry staining of endometrial carcinoma and corresponding uninvolved tissues showed that CYP17 is upregulated in endometrial cancers (15 of 24, 62.5%). To understand the functional significance of this upregulation, we silenced CYP17 gene by introduction of siRNA into endometrial cancer cell line KLE followed by functional studies. Further, to understand the molecular basis of the role of CYP17, we profiled the expression of key pathway-specific genes and identified several components of the apoptosis and invasion pathways that are potentially regulated by CYP17. Silencing of CYP17 caused decreased cell proliferation and induced apoptosis. Significantly, CYP17 depletion leads to downregulation of anti-apoptotic genes B cell lymphoma 2 (Bcl-2) and telomerase reverse transcriptase (TERT), indicating induced apoptosis. Also, attenuation of CYP17 decreased the cellular invasion ability and regulated expression of several invasion pathway components such as melanoma cell adhesion molecule (MCAM), matrix metallopeptidase 2 and 9 (MMP-2 and MMP-9), and tissue inhibitor of metalloproteinase 3 (TIMP3). In conclusion, this is the first report documenting that upregulation of CYP17 in endometrial cancers play a crucial role in endometrial carcinogenesis by targeting multiple components of apoptosis and invasion pathways. Further studies are required to understand the detailed mechanisms underlying CYP17-mediated regulation of these components.

Adherence to the dietary guidelines for Americans and endometrial cancer risk

The Healthy Eating Index (HEI) was developed by the US Department of Agriculture with the goal of quantifying adherence to the Dietary Guidelines for Americans. The purpose of this study was to evaluate the impact of the HEI-2005 score and each of its components on endometrial cancer risk in a population-based case-control study in New Jersey. A total of 424 cases and 398 controls completed a Food Frequency Questionnaire, which was used to derive the HEI-2005 score. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression while adjusting for potential covariates, which included all major endometrial cancer risk factors. The adjusted OR for women in the highest quartile when compared to the lowest quartile was 0.83 (95% CI: 0.52-1.34). For the meat and beans component comprising meat, eggs, poultry, fish, and beans, the OR was 0.70 (95% CI: 0.45-1.11; p for trend: 0.07), with little evidence of an association with any of the individual foods. There was no indication of an association for any of the other components of the HEI or of effect modification by body mass index. This study suggested limited value for the HEI-2005 in predicting endometrial cancer risk.

Coffee and tea consumption and endometrial cancer risk in a population-based study in New Jersey

We evaluated the role of tea and coffee and substances added (sugar/honey, creamers, and milk) on endometrial cancer risk in a population-based case-control study in six counties in New Jersey, including 417 cases and 395 controls. Multivariate odds ratios (OR) and 95% confidence intervals (CI) were computed using unconditional logistic regression. There was a moderate inverse association with coffee consumption, with an adjusted OR of 0.65 (95% CI: 0.36-1.17) for women who reported more than two cups/day of coffee compared to none. Tea consumption appeared to increase risk (OR: 1.93; 95% CI: 1.08-3.45), but after including the variables sugar/honey and cream/milk added to tea in the model, the risk estimate was attenuated and no longer statistically significant (OR: 1.77; 95% CI: 0.96-3.28 for those consuming more than one cup/day of tea compared to nonusers). There was a suggestion of a decreased risk associated with green tea, but the confidence interval included one (adjusted OR for one or more cups/week vs. none: 0.75; 95% CI: 0.48-1.18). We found an association with adding sugar/honey to tea, with those adding two or more teaspoons/cup having an OR of 2.66 (95% CI: 1.42-4.98; p for trend <0.01) after adjusting for relevant confounders. For sugar/honey added to coffee the corresponding OR was 1.43 (95% CI: 0.81-2.55). Our results indicate that sugars and milk/cream added to coffee and tea should be considered in future studies evaluating coffee and tea and endometrial cancer risk.

Genetic variation in CYP11A1 and StAR in relation to endometrial cancer risk

OBJECTIVE

Together, steroidogenic acute regulator (StAR) and the cholesterol side chain cleavage enzyme (P450scc), which is encoded by CYP11A1, mediate the initial and rate-limiting step in steroidogenesis. Given the role of estrogens in endometrial carcinogenesis, we hypothesized that genetic variation in StAR and CYP11A1 genes may influence endometrial cancer risk.

METHODS

We genotyped four CYP11A1 tagging single nucleotide polymorphisms (SNPs) and two StAR SNPs in endometrial cancer case-control studies nested within the Nurses' Health Study (553 cases and 1339 controls) and the Women's Health Study (137 cases and 411 controls). We calculated odds ratios and 95% confidence intervals using conditional and unconditional logistic regression adjusted for endometrial cancer risk factors to examine the association between SNPs/haplotypes and endometrial cancer.

RESULTS

We observed an increased risk for women carrying the variant allele for rs4555110 (odds ratio (OR)=1.3, 95% confidence interval (CI)=1.1-1.7), rs3825944 (OR=1.4, 95% CI=1.1-1.8), and rs7173655 (OR=1.3, 95% CI=1.0-1.7) CYP11A1 SNPs but no significant associations with CYP11A1 haplotypes. CYP11A1 SNPs were not predictive of plasma estradiol levels. We observed no associations between StAR SNPs and endometrial cancer risk.

CONCLUSIONS

Genetic variants in CYP11A1 may influence endometrial cancer risk or may be markers for causal variants elsewhere. Polymorphisms in StAR are not associated with endometrial cancer risk, but further research is needed.

Common genetic variation in the sex hormone metabolic pathway and endometrial cancer risk: pathway-based evaluation of candidate genes

BACKGROUND

Estrogen plays a major role in endometrial carcinogenesis, suggesting that common variants of genes in the sex hormone metabolic pathway may be related to endometrial cancer risk. In support of this view, variants in CYP19A1 [cytochrome P450 (CYP), family 19, subfamily A, polypeptide 1] have been associated with both circulating estrogen levels and endometrial cancer risk. Associations with variants in other genes have been suggested, but findings have been inconsistent.

METHODS

We examined 36 sex hormone-related genes using a tagging approach in a population-based case-control study of 417 endometrial cancer cases and 407 controls conducted in Poland. We evaluated common variation in these genes in relation to endometrial cancer risk using sequential haplotype scan, variable-sized sliding window and adaptive rank-truncated product (ARTP) methods.

RESULTS

In our case-control study, the strongest association with endometrial cancer risk was for AR (androgen receptor; ARTP P = 0.006). Multilocus analyses also identified boundaries for a region of interest in AR and in CYP19A1 around a previously identified susceptibility loci. We did not find evidence for consistent associations between previously reported candidate single-nucleotide polymorphisms in this pathway and endometrial cancer risk.

DISCUSSION

In summary, we identified regions in AR and CYP19A1 that are of interest for further evaluation in relation to endometrial cancer risk in future haplotype and subsequent fine mapping studies in larger study populations.

Phytoestrogen consumption and endometrial cancer risk: a population-based case-control study in New Jersey

Phytoestrogens have been shown to exert anti-estrogenic and estrogenic effects in some tissues, including the breast. However, only a few studies have evaluated their role in endometrial cancer risk. We evaluated this association in a population-based case-control study in New Jersey. A total of 424 cases and 398 controls completed an interview, including a food frequency questionnaire with supplemental questions for phytoestrogen foods. Risk estimates were derived using an unconditional logistic regression, adjusting for major risk factors for endometrial cancer. There was some suggestion of a decreased risk with quercetin intake (OR: 0.65; 95% CI: 0.41-1.01 for the highest compared to the lowest quartile; p for trend: 0.02). We found a limited evidence of an association with any of the lignans evaluated, total lignans, coumestrol, individual isoflavones, total isoflavones, or total phytoestrogens. However, there was some suggestion of an inverse association with total isoflavone intake limited to lean women (BMI <25; OR for the highest tertile: 0.50; 95% CI: 0.25-0.98) and those with a waist-to-hip ratio <or=0.85 (OR: 0.59; 95% CI: 0.33-1.05). There was no evidence of effect modification by HRT use. This study suggests a reduction in endometrial cancer risk with quercetin intake and with isoflavone intake in lean women.

Two estrogen-related variants in CYP19A1 and endometrial cancer risk: a pooled analysis in the Epidemiology of Endometrial Cancer Consortium

Common variants in CYP19A1 (the A alleles of rs749292 and rs727479) have been associated with a 10% to 20% increase in circulating estrogen levels in postmenopausal women. We hypothesized that the presence of one or both A alleles in these single nucleotide polymorphisms (SNP) is associated with increased endometrial cancer risk. We tested this hypothesis in a large pooled analysis of 4,998 endometrial cancer cases and 8,285 controls from 10 studies in the Epidemiology of Endometrial Cancer Consortium. The majority of women (>66%) were whites, with smaller proportions of other races and ethnic groups (blacks, Asians, and Latinas) also included in this pooled analysis. Unconditional logistic regression was used to model the association between SNPs/haplotypes and endometrial cancer risk. Carrying the A allele of either of these SNPs was associated with an increased risk of endometrial cancer, with pooled odds ratios per allele of 1.14, 95% confidence interval of 1.09-1.21, and P = 7.1 x 10(-7) for rs749292, and odds ratio per allele of 1.08, 95% confidence interval of 1.02-1.14, and P = 0.009 for rs727479. For rs749292, these associations were generally stronger among women age >or=55 years. For both SNPs, risk increased with increasing body mass index, and for rs727479, this pattern seemed stronger among women age >or=55 years (P interaction = 0.007). The combination of A alleles in the two SNPs, either by direct count or by haplotype analysis, did not increase risk above that observed for the individual SNPs. Our study provides evidence that CYP19A1 genetic variation influences susceptibility to endometrial cancer, particularly among older and obese women.

Maximizing resources to study an uncommon cancer: E2C2--Epidemiology of Endometrial Cancer Consortium

Endometrial cancer affects more than 40,000 women a year in the U.S. While the association of this disease with high body mass index and sex steroid hormones is well known, there are many questions about etiology that have not been resolved. Little is known about the genetic basis for risk associated with hormones or obesity, other common genetic factors associated with risk, or gene-environment interactions. E2C2, the Epidemiology of Endometrial Cancer Consortium, was formed in 2006 to provide a collaborative environment for addressing these questions by pooling data from existing studies. This allows for investigations of uncommon risk factors, risk for rare histologic subtypes, and associations within strata that cannot be achieved in individual studies. This report describes the establishment of the consortium, ongoing projects that demonstrate the advantages of collaborative efforts, and challenges faced. Overall, the consortium promises to provide an important means of furthering our knowledge about this cancer.