Early life environment, life history and risk of endometrial cancer

Parenting style in childhood and mortality risk at older ages: a longitudinal cohort study

BACKGROUND

Parenting style is associated with offspring health, but whether it is associated with offspring mortality at older ages remains unknown.

AIMS

We examined whether childhood experiences of suboptimal parenting style are associated with increased risk of death at older ages.

METHOD

Longitudinal cohort study of 1964 community-dwelling adults aged 65-79 years.

RESULTS

The association between parenting style and mortality was inverse and graded. Participants in the poorest parenting style score quartile had increased risk of death (hazard ratio (HR) = 1.72, 95% CI 1.20-2.48) compared with those in the optimal parenting style score quartile after adjustment for age and gender. Full adjustment for covariates partially explained this association (HR = 1.49, 95% CI 1.02-2.18). Parenting style was inversely associated with cancer and other mortality, but not cardiovascular mortality. Maternal and paternal parenting styles were individually associated with mortality.

CONCLUSIONS

Experiences of suboptimal parenting in childhood are associated with increased risk of death at older ages.

Prenatal smoking and age at menarche: influence of the prenatal environment on the timing of puberty

STUDY QUESTION

Do prenatal exposure to cigarette smoking and birthweight influence age at menarche (AAM) in a cohort of Australian girls?

SUMMARY ANSWER

We find that prenatal smoke exposure and lower birthweight increase the chance of earlier menarche in accordance with theoretical predictions as do confounding factors of maternal AAM and higher BMI of the girls.

WHAT IS KNOWN ALREADY

Much prior research focuses on the role of the early childhood environment in determining AAM but fewer studies consider the role of the prenatal environment. Those studies that examine the prenatal period find an acceleration of maturation associated with maternal smoking and low birthweight. Life history theory predicts that early life exposure to stressful environments should promote more rapid maturation and that this timing can be established before birth, making the prenatal environment particularly important.

STUDY DESIGN, SIZE, DURATION

Statistical analysis of longitudinal survey data collected from a large cohort (n = 2446) of Australian children using data from birth to 12-13 years of age.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Owing to missing data, 1493 girls were included in the final analysis. Using cox regression, we examine how (i) maternal cigarette smoking during gestation and (ii) birthweight influence girls' AAM. Cox regression was used because not all girls had reached menarche.

MAIN RESULTS AND THE ROLE OF CHANCE

We find that older maternal AAM (hazards ratio (HR): 0.75, confidence interval (CI) (95%): 0.71-0.79) and higher birthweight (HR: 0.86, CI (95%): 0.75-0.97) lower the chance of earlier menarche; while higher girls' BMI at 8-9 years (HR: 1.12, CI (95%): 1.10-1.15), and maternal cigarette smoking on 'most days' during gestation (HR: 1.40, CI (95%): 1.10-1.79 with 'no smoking' as the reference level) increased the chance of earlier menarche. All factors were statistically significant at P = 0.05.

LIMITATIONS, REASONS FOR CAUTION

Not all girls had reached menarche, necessitating the use of cox regression. As with other longitudinal studies, there was study sample attrition and some missing data, particularly in reports of maternal smoking. In addition, as the degree of bias in the missing data is unknown, possible inaccurate reporting of maternal smoking may influence the results of birthweight on AAM.

WIDER IMPLICATIONS OF THE FINDINGS

Because of the association between younger AAM and higher risk of uterine, endometrial and breast cancer development, our finding adds to the need to consider the stress caused by prenatal smoke exposure as an important health risk. In addition, this study needs to be extended, when the same girls are 14-15 years of age, and on a larger dataset from a younger cohort within the same Australian Government project.

STUDY FUNDING/COMPETING INTERESTS

No funding was received for this study and there are no competing interests to declare.

The occurrence of fetal microchimeric cells in endometrial tissues is a very common phenomenon in benign uterine disorders, and the lower prevalence of fetal microchimerism is associated with better uterine cancer prognoses

This is the first study carried out to describe the role of fetal microchimerism (FM) in the pathogenesis of uterine cancer. The prevalence and concentration of male fetal microchimeric cells (FMCs) were examined in endometrial tissues in relation to subtypes of uterine cancer, and the histological grade and stage of the tumor. FM occurrence was analyzed in relation to risk factors, including hypertension, obesity, type 2 diabetes, dyslipidemia, age at cancer diagnosis, and patient pregnancy history. The prevalence and concentration of FMCs were examined in endometrial tissues using real-time polymerase chain reaction, SRY and β-globin sequences as markers for male fetal FMCs and total DNA. The studied group involved 47 type 1 endometrial cancers, 28 type 2 endometrial cancers, and 41 benign uterine diseases. While the prevalence of FM was decreased only in type 1 endometrial cancer, compared with benign uterine disorders (38.3% vs.70.7%; odds ratio [OR]=0.257, 95% confidence interval [CI]: 0.105 to 0.628, p=0.003), FMC concentrations did not differ within examined groups. The lower FM prevalence was detected in low-grade (grade 1 and grade 2) endometrioid cancer (38.3% vs. 70.7%, OR=0.256, 95% CI: 0.105 to 0.627, p=0.003) and in FIGO 1 tumors (40.7% vs. 70.7%, OR=0.285, 95% CI: 0.120 to 0.675, p=0.004). No correlation between FM prevalence or FMC concentrations and risk factors was demonstrated. A lower prevalence of male FM seemed to be associated with better prognoses in uterine cancer based on tumor subtype, histological grade, and stage of the tumor.

Expression of estrogen receptors (α, β), cyclooxygenase-2 and aromatase in normal endometrium and endometrioid cancer of uterus

PURPOSE

Endometrial cancer (EC) is one of the most common malignancies of the female genital tract, but the etiology, especially its metabolism is still investigated. The aim of this study was to evaluate the presence and relative expression of Estrogen Receptors (α, β), Cyclooxygenase-2 and Aromatase in both endometrial cancer and normal mucosa.

MATERIAL/METHODS

Two groups of women were selected for the study: 1) patients with endometrioid endometrial cancer (FIGO I; G1 - G3) (n=35) and 2) subjects with normal endometrial tissue (control group, n=29). The expression of Estrogen Receptors (ERα, β), Cyclooxygenase-2 (COX-2), Aromatase were estimated by Western blot analysis. Furthermore, the associations between FIGO classification (stage: Ia, Ib), tumor grade (G) and expression of ERα, β, COX-2, aromatase proteins were evaluated. Overall and disease-free survival curves were generated according to the Kaplan-Meier method. Median follow-up time of the patients examined in this study was 39 months.

RESULTS

The relative expression of each examined protein was markedly higher in the endometrial cancer tissue as compared to the healthy endometrium. The trends towards greater expression along with a tumor progression was noticed (FIGO stage: Ia vs. Ib). Analysis of endometrial cancer risk factors and their influence on survival curves showed only an inverse significant correlations between obesity (BMI: 36.2; n=21) and disease-free survival in EC group (p=0.00872), but there was no significant association between obesity and overall survival (p=0.358).

CONCLUSIONS

Endometrioid endometrial cancer shows relatively higher expression of either ER, COX-2 and aromatase comparing to healthy mucosa, suggesting their involvement in tumor development and progression.

Genetic variation and reproductive timing: African American women from the Population Architecture using Genomics and Epidemiology (PAGE) Study

Age at menarche (AM) and age at natural menopause (ANM) define the boundaries of the reproductive lifespan in women. Their timing is associated with various diseases, including cancer and cardiovascular disease. Genome-wide association studies have identified several genetic variants associated with either AM or ANM in populations of largely European or Asian descent women. The extent to which these associations generalize to diverse populations remains unknown. Therefore, we sought to replicate previously reported AM and ANM findings and to identify novel AM and ANM variants using the Metabochip (n = 161,098 SNPs) in 4,159 and 1,860 African American women, respectively, in the Women's Health Initiative (WHI) and Atherosclerosis Risk in Communities (ARIC) studies, as part of the Population Architecture using Genomics and Epidemiology (PAGE) Study. We replicated or generalized one previously identified variant for AM, rs1361108/CENPW, and two variants for ANM, rs897798/BRSK1 and rs769450/APOE, to our African American cohort. Overall, generalization of the majority of previously-identified variants for AM and ANM, including LIN28B and MCM8, was not observed in this African American sample. We identified three novel loci associated with ANM that reached significance after multiple testing correction (LDLR rs189596789, p = 5×10⁻⁰⁸; KCNQ1 rs79972789, p = 1.9×10⁻⁰⁷; COL4A3BP rs181686584, p = 2.9×10⁻⁰⁷). Our most significant AM association was upstream of RSF1, a gene implicated in ovarian and breast cancers (rs11604207, p = 1.6×10⁻⁰⁶). While most associations were identified in either AM or ANM, we did identify genes suggestively associated with both: PHACTR1 and ARHGAP42. The lack of generalization coupled with the potentially novel associations identified here emphasize the need for additional genetic discovery efforts for AM and ANM in diverse populations.

A novel quantitative approach to women's reproductive strategies

The patterned way in which individuals allocate finite resources to various components of reproduction (e.g. mating effort, reproductive timing and parental investment) is described as a reproductive strategy. As energy is limited, trade-offs between and within aspects of reproductive strategies are expected. The first aim of this study was to derive aspects of reproductive strategies using complete reproductive histories from 718 parous Western Australian women. Factor analysis using a subset of these participants resulted in six factors that represented 'short-term mating strategy', 'early onset of sexual activity', 'reproductive output', 'timing of childbearing', 'breastfeeding', and 'child spacing'. This factor structure was internally validated by replication using a second independent subset of the data. The second aim of this study examined trade-offs between aspects of reproductive strategies derived from aim one. Factor scores calculated for each woman were incorporated in generalised linear models and interaction terms were employed to examine the effect of mating behaviour on the relationships between reproductive timing, parental investment and overall reproductive success. Early sexual activity correlates with early reproductive onset for women displaying more long-term mating strategies. Women with more short-term mating strategies exhibit a trade-off between child quantity and child quality not observed in women with a long-term mating strategy. However, women with a short-term mating strategy who delay reproductive timing exhibit levels of parental investment (measured as breastfeeding duration per child) similar to that of women with long-term mating strategies. Reproductive delay has fitness costs (fewer births) for women displaying more short-term mating strategies. We provide empirical evidence that reproductive histories of contemporary women reflect aspects of reproductive strategies, and associations between these strategic elements, as predicted from life history theory.