Preeclampsia and maternal breast cancer risk by offspring gender: do elevated androgen concentrations play a role?

Gestational Hypertensive Disorders and Maternal Breast Cancer Risk in a Nationwide Cohort of 40,720 Parous Women

BACKGROUND

Preeclampsia and gestational hypertension are hypothesized to be associated with reduced maternal breast cancer risk, but the epidemiologic evidence is inconclusive. Our objective was to examine associations between gestational hypertensive disorders and breast cancer in a nationwide cohort of women with a family history of breast cancer.

METHODS

Women ages 35-74 years who had a sister previously diagnosed with breast cancer, but had never had breast cancer themselves, were enrolled in the Sister Study from 2003 to 2009 (N = 50,884). At enrollment, participants reported diagnoses of eclampsia, preeclampsia, or gestational hypertension in each pregnancy. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between history of a gestational hypertensive disorder and incident invasive breast cancer or ductal carcinoma in situ among 40,720 parous women. We used age as the time scale and adjusted for birth cohort, race-ethnicity, and reproductive, socioeconomic, and behavioral factors. We examined effect measure modification by risk factors for gestational hypertensive disease and breast cancer and assessed possible etiologic heterogeneity across tumor characteristics.

RESULTS

The prevalence of gestational hypertensive disease was 12%. During follow-up (mean = 10.9 years), 3,198 eligible women self-reported a breast cancer diagnosis. History of a gestational hypertensive disorder was not associated with breast cancer risk (HR = 1.0; 95% CI = 0.90, 1.1). We did not observe clear evidence of effect measure modification or etiologic heterogeneity.

CONCLUSIONS

History of a gestational hypertensive disorder was not associated with breast cancer risk in a cohort of women with a first-degree family history of breast cancer.

Hypertensive diseases of pregnancy and risk of breast cancer in the Black Women's Health Study

PURPOSE

Compared to white women, Black women have increased risk of developing hypertensive diseases of pregnancy (HDOP) and have a higher incidence of aggressive breast cancer subtypes. Few studies of HDOP and breast cancer risk have included large numbers of Black women. This study examined the relation of HDOP to incidence of breast cancer overall and by estrogen receptor (ER) status in Black women.

METHODS

We followed 42,982 parous women in the Black Women's Health Study, a nationwide prospective study of Black women. Multivariable Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) to assess associations of self-reported HDOP, including preeclampsia and gestational hypertension, with breast cancer incidence overall and by ER subtype, adjusted for age and established breast cancer risk factors.

RESULTS

Over 20 years of follow-up, we identified 2376 incident breast cancer cases. History of HDOP (11.7%) was not associated with breast cancer risk overall (HR 0.98; 95% CI 0.87, 1.11). HRs for invasive ER+ and ER- breast cancer were 1.11 (95% CI 0.93, 1.34) and 0.81 (95% CI 0.61, 1.07), respectively.

CONCLUSIONS

HDOP was not associated with risk of overall breast cancer in Black women. A suggestive inverse association with ER- breast cancer may reflect an anti-tumorigenic hormone profile in HDOP, but those results require confirmation in other studies.

Heightened susceptibility: A review of how pregnancy and chemical exposures influence maternal health

Pregnancy is a unique period when biological changes can increase sensitivity to chemical exposures. Pregnant women are exposed to multiple environmental chemicals via air, food, water, and consumer products, including flame retardants, plasticizers, and pesticides. Lead exposure increases risk of pregnancy-induced hypertensive disorders, although women's health risks are poorly characterized for most chemicals. Research on prenatal exposures has focused on fetal outcomes and less on maternal outcomes. We reviewed epidemiologic literature on chemical exposures during pregnancy and three maternal outcomes: preeclampsia, gestational diabetes, and breast cancer. We found that pregnancy can heighten susceptibility to environmental chemicals and women's health risks, although variations in study design and exposure assessment limited study comparability. Future research should include pregnancy as a critical period for women's health. Incorporating biomarkers of exposure and effect, deliberate timing and method of measurement, and consistent adjustment of potential confounders would strengthen research on the exposome and women's health.

Pre-eclampsia: pathophysiology and clinical implications

Pre-eclampsia is a common disorder that particularly affects first pregnancies. The clinical presentation is highly variable but hypertension and proteinuria are usually seen. These systemic signs arise from soluble factors released from the placenta as a result of a response to stress of syncytiotrophoblast. There are two sub-types: early and late onset pre-eclampsia, with others almost certainly yet to be identified. Early onset pre-eclampsia arises owing to defective placentation, whilst late onset pre-eclampsia may center around interactions between normal senescence of the placenta and a maternal genetic predisposition to cardiovascular and metabolic disease. The causes, placental and maternal, vary among individuals. Recent research has focused on placental-uterine interactions in early pregnancy. The aim now is to translate these findings into new ways to predict, prevent, and treat pre-eclampsia.

Pregnancy complications and subsequent breast cancer risk in the mother: a Nordic population-based case-control study

Certain features of pregnancy are important risk factors for breast cancer, such as protection afforded by young age at first birth. Preeclampsia, a pregnancy complication, is associated with reduced maternal breast cancer risk. However, questions remain regarding causality, biological mechanisms and the relation of other hypertensive conditions to risk. We conducted a population-based case-control study of breast cancer cases (n = 116,196) in parous women identified through linkage of birth and cancer registries in Denmark, Finland, Norway and Sweden (1967-2013), including up to 10 matched controls per case (n = 1,147,192) sampled from the birth registries (complete data were not available on all variables). Odds ratios (ORs) with 95% confidence intervals (CIs) were derived from unconditional logistic regression models including matching factors (country, maternal birth year) and parity. Hypertension diagnosed before pregnancy (OR 0.87; 95% CI 0.78-0.97), gestational hypertension (OR 0.90; 95% CI 0.86-0.93) and preeclampsia (OR 0.91; 95% CI 0.88-0.95) were associated with reduced breast cancer risk. Results remained similar after adjustment for smoking and maternal body mass index before first pregnancy, and were generally similar stratified by parity, age at breast cancer diagnosis, time since first and last birth, sex of the offspring and calendar time. Except for retained placenta (OR 1.14; 95% CI 0.98-1.32), no other pregnancy complication appeared associated with breast cancer risk. The mechanisms mediating the modest risk reductions for history of preeclampsia or hypertension preceding or arising during pregnancy, and possible increased risk with history of retained placenta are unknown and warrant further laboratory, clinical and epidemiological investigation.

Breast cancer risk in relation to history of preeclampsia and hyperemesis gravidarum: Prospective analysis in the Generations Study

Preeclampsia and hyperemesis gravidarum are pregnancy complications associated with altered sex hormone levels. Previous studies suggest preeclampsia may be associated with a decreased risk of subsequent breast cancer and hyperemesis with an increased risk, but the evidence remains unclear. We used data from the Generations Study, a large prospective study of women in the United Kingdom, to estimate relative risks of breast cancer in relation to a history of preeclampsia and hyperemesis using Cox regression adjusting for known breast cancer risk factors. During 7.5 years average follow‐up of 82,053 parous women, 1,969 were diagnosed with invasive or in situ breast cancer. Women who had experienced preeclampsia during pregnancy had a significantly decreased risk of premenopausal breast cancer (hazard ratio (HR) =0.67, 95% confidence interval (CI): 0.49–0.90) and of HER2‐enriched tumours (HR = 0.33, 95% CI: 0.12–0.91), but there was no association with overall (HR = 0.90, 95% CI: 0.80–1.02) or postmenopausal (HR = 0.97, 95% CI: 0.85–1.12) breast cancer risk. Risk reductions among premenopausal women were strongest within 20 years since the last pregnancy with preeclampsia. Hyperemesis was associated with a significantly increased risk of HER2‐enriched tumours (HR = 1.76, 95% CI: 1.07–2.87), but not with other intrinsic subtypes or breast cancer risk overall. These results provide evidence that preeclampsia is associated with a decreased risk of premenopausal and HER2‐enriched breast cancer and that hyperemesis, although not associated with breast cancer risk overall, may be associated with raised risk of HER2‐enriched tumours.

What's new?

Although the link of preeclampsia and hyperemesis gravidarum with altered sex hormone levels is well established, relatively little is known about the association of these pregnancy complications with breast cancer risk. Here, the authors found that a history of preeclampsia decreased the risk of premenopausal breast cancer and tumors enriched for the receptor tyrosine‐protein kinase HER2. In contrast, hyperemesis gravidarum increased the risk to develop HER2‐enriched tumors, pointing to nuanced differences of sex hormone alterations during pregnancy with respect to breast cancer subtypes and menopausal status.

Do racial differences exist in the association between pregnancy-induced hypertension and breast cancer risk?

BACKGROUND

Previous studies investigating the relationship between pregnancy-induced hypertension (PIH) and breast cancer risk have yielded inconsistent results. Unlike numerous Western studies, studies have reported that PIH may be a risk factor for breast cancer in Western Asian women. To confirm these results, we designed a retrospective population-based cohort study to assess the relationship between PIH and subsequent risk for breast cancer in Taiwan.

METHODS

Patients with newly diagnosed PIH were selected from the Taiwan National Health Insurance Research Database (NHIRD), and a 1:4 matched cohort of women without PIH based on age and the year of delivery was randomly selected from the same database as the comparison group. The incidence of new-onset breast cancer was assessed in both cohorts.

RESULTS

Among the 23.3 million individuals registered in the NHIRD, 26,638 patients with PIH and 106,552 matched controls were identified. The incidence rate of breast cancer was higher in patients with PIH than in the matched controls (incidence rate ratio = 1.09, 95% confidence interval [CI] = 1.09-1.10, p < 0.0001). However, the Kaplan-Meier analysis revealed a similar cumulative incidence rate of breast cancer between the PIH and comparison cohorts (log-rank p = 0.4303). Moreover, results from a multivariate analysis indicated that PIH was not a statistically significant independent risk factor for breast cancer (adjusted hazard ratio = 1.10, 95% CI = 0.87-1.39, p = 0.4247).

CONCLUSIONS

The present study demonstrated no significant temporal relationship between PIH and risk for subsequent breast cancer in Eastern Asian women.

Perinatal androgen exposure and adipose tissue programming: is there an impact on body weight fate?

Obesity is a major concern in public health because it is one of the main risk factors for the development of non-transmissible chronic diseases. The fact that there is a clear sex dimorphism in normal body fat distribution points out the role of sex steroids as key factors in the regulation and function of the adipose cell. Androgens affect adipogenesis and fat metabolism in the adipose tissue of males and females. Hormonal disorders during pregnancy may affect the fetal tissues, with long-term implications leading to the development of pathologies during adult life. Obesity and metabolic disease are among these. In this regard, animal models have demonstrated an abnormal fat distribution and modifications in the size and function of adipose cells in the female and male offspring of mothers exposed to androgen excess during pregnancy.

Preeclampsia and breast cancer: The influence of birth characteristics

BACKGROUND

In parous women preeclampsia has been associated with reduced risk of developing breast cancer. Characteristics of births following preeclamptic pregnancies may help understand mechanisms involved in the breast cancer risk reduction inferred by preeclampsia.

METHODS

We conducted a register-based cohort study of all Danish women giving birth during 1978-2010 (n = 778,701). The association between preeclampsia and breast cancer was evaluated overall and according to birth characteristics by means of incidence rate ratios (IRR) estimated in Poisson regression models.

RESULTS

Compared with women with non-preeclamptic pregnancies only, women with one or more preeclamptic pregnancies were 19% significantly less likely to develop breast cancer (IRR = 0.81 [95% CI 0.72-0.93]). We found some indication of greater risk reduction in women with term births, one or more previous births, and in women giving birth to boys. These findings, however, did not reach statistical significance. Finally, risk reduction was slightly greater following milder forms of preeclampsia.

CONCLUSION

Our data is compatible with an approximately 20% reduction in risk of developing breast cancer following preeclampsia. Although we find some variability according to birth characteristics, the risk reduction inferred by preeclampsia seems applicable to most preeclamptic pregnancies.

In utero preeclampsia exposure, milk intake and pubertal development

Cord blood insulin-like growth factor-1 (IGF-1) concentrations are lower in preeclamptic (PE) than normotensive (NT) pregnancies. PE offspring have increased risk of cardiovascular disease and decreased risk of some cancers including breast. We examined the effects of PE exposure in utero, infant feeding and childhood diet at 3-5 years on IGF-1 and breast development in 194 female offspring who were followed from birth until follow-ups at 10.8 and 12.9 years. Diet was not associated with serum IGF-1 levels at 10.8 years. PE exposure was associated with reduced odds of thelarche at 10.8 years only among exclusively breastfed girls. Milk, butter and ice cream consumption at 3-5 years was inversely related to the OR of breast development at 10.8 years. Child's weight and maternal overweight were positively associated with breast development at 10.8 years; child's height and weight were positively associated with breast development at 12.9 years.

Malignant cancer and invasive placentation: A case for positive pleiotropy between endometrial and malignancy phenotypes

Cancer metastasis is an invasive process that involves the transplantation of cells into new environments. Since human placentation is also invasive, hypotheses about a relationship between invasive placentation in eutherian mammals and metastasis have been proposed. The relationship between metastatic cancer and invasive placentation is usually presented in terms of antagonistic pleiotropy. According to this hypothesis, evolution of invasive placentation also established the mechanisms for cancer metastasis. Here, in contrast, we argue that the secondary evolution of less invasive placentation in some mammalian lineages may have resulted in positive pleiotropic effects on cancer survival by lowering malignancy rates. These positive pleiotropic effects would manifest themselves as resistance to cancer cell invasion. To provide a preliminary test of this proposal, we re-analyze data from Priester and Mantel (Occurrence of tumors in domestic animals. Data from 12 United States and Canadian colleges of veterinary medicine. J Natl Cancer Inst 1971; 47: :1333-44) about malignancy rates in cows, horses, cats and dogs. From our analysis we found that equines and bovines, animals with less invasive placentation, have lower rates of metastatic cancer than felines and canines in skin and glandular epithelial cancers as well as connective tissue sarcomas. We conclude that a link between type of placentation and species-specific malignancy rates is more likely related to derived mechanisms that suppress invasion rather than different degrees of fetal placental aggressiveness.

The relationship between preeclampsia, pregnancy-induced hypertension and maternal risk of breast cancer: a meta-analysis

BACKGROUND

It has long been recognized that some human breast cancers are hormone dependent. Preeclampsia is a syndrome of pregnancy defined by the onset of hypertension and proteinuria and characterized by dysfunction of the maternal endothelium. Many hormonal changes occur with preeclampsia, and we hypothesize that these changes may influence the risk of maternal breast cancer. We also analyzed the relation between pregnancy-induced hypertension (PIH) and maternal risk of breast cancer.

METHODS

Among 13 relevant publications about preeclampsia and six relevant publications about PIH, some studies find preeclampsia associated with a lower risk of breast cancer, but others did not. Therefore, these results are inconclusive. We conducted meta-analysis to evaluate more precisely the relationship between preeclampsia, PIH and maternal risk of breast cancer.

RESULTS

The pooled estimate of the hazard ratio (HR) associated with preeclampsia was 0.86 (95% CI 0.73-1.01), and that associated with PIH was 0.83 (0.66-1.06), both based on the random effects model.

CONCLUSION

Some suggestive but not entirely consistent nor conclusive evidence was found on the association between the history of preeclampsia or PIH with the subsequent risk of breast cancer.

Hypertensive diseases in pregnancy and breast cancer risk

Background:

Hypertensive diseases in pregnancy may be associated with a reduced risk of breast cancer. Most previous studies are small and have shown conflicting results.

Methods:

In a cohort of 919 712 women who gave their first birth between 1967 and 2008, with linkage of information from two national registries, we assessed whether women with pregnancy hypertensive diseases are at reduced breast cancer risk. We used Cox regression to estimate hazard ratios (HRs) with 95% confidence intervals (CI).

Results:

Compared with women with a normotensive first pregnancy, women with hypertension or preeclampsia in their first pregnancy had a reduced breast cancer risk (HR 0.83, 95% CI 0.77, 0.90). A reduced risk was consistently observed for hypertensive disease in any pregnancy, for recurrent hypertensive disease in pregnancy, and before and after 50 years of age at breast cancer diagnosis. The association was strongest for women with hypertension in pregnancy, who delivered at term/post-term (HR 0.81, 95% CI 0.75, 0.88) or had a child of average birth weight (HR 0.77, 95% CI 0.69, 0.85).

Conclusion:

Women with pregnancy hypertensive diseases are at reduced breast cancer risk. Whether this association can be attributed to pregnancy-specific events or to underlying biological traits remains unclear.

Pregnancy characteristics and maternal breast cancer risk: a review of the epidemiologic literature

The short- and long-term effects of pregnancy on breast cancer risk are well documented. Insight into potential biological mechanisms for these associations may be gained by studying breast cancer risk and pregnancy characteristics (e.g., preeclampsia, twining), which may reflect hormone levels during pregnancy. To date, no review has synthesized the published literature for pregnancy characteristics and maternal breast cancer using systematic search methods. We conducted a systematic search to identify all published studies. Using PUBMED (to 31 July 2009), 42 relevant articles were identified. Several studies suggest that multiple births may be associated with a lowered breast cancer risk of about 10-30%, but results were inconsistent across 18 studies. The majority of 13 studies suggest about a 20-30% reduction in risk with preeclampsia and/or gestational hypertension. Six of seven studies reported no association for infant sex and breast cancer risk. Data are sparse and conflicting for other pregnancy characteristics such as gestational age, fetal growth, pregnancy weight gain, gestational diabetes, and placental abnormalities. The most consistent findings in a generally sparse literature are that multiple births and preeclampsia may modestly reduce breast cancer risk. Additional research is needed to elucidate associations between pregnancy characteristics, related hormonal profiles, and breast cancer risk.

Placental ischemia and breast cancer risk after preeclampsia: tying the knot

Although hypertensive disorders of pregnancy, such as preeclampsia, continue to be a significant source of maternal and fetal morbidity and mortality, there is emerging evidence that effects of the preeclamptic syndrome persist into later life. In contrast to recent studies that have reported that formerly preeclamptic women are at increased risk for cardiovascular disease, it appears that preeclampsia may be associated with a decreased risk of breast cancer. Recent investigations have provided exciting new insights into potential mechanisms underlying the pathogenesis of preeclampsia and some of these findings may bear relevance to the anticancer effects reported in the epidemiological literature. Placental ischemia is regarded to be a primary factor in preeclampsia and the ischemic placenta produces a variety of factors that generate profound effects on endothelial cell function and the cardiovascular system during pregnancy. Moreover, several of these factors are reportedly elevated many years after preeclamptic pregnancies. This group of molecules includes factors such as soluble fms-like tyrosine kinase-1 (sFlt-1), soluble endoglin/CD105 (sEng) and various cytokines. Many of these factors have been strongly associated with cancer incidence and, hence, could contribute to the modification of cancer risk observed in these women. Therefore, identifying potential connections between placental dysfunction and future cancer risk is an important endeavor towards realizing novel therapeutic regimens for cancer patients.

Preeclampsia and subsequent risk of cancer: update from the Jerusalem Perinatal Study

OBJECTIVE

The purpose of this study was to examine the association between preeclampsia and cancer incidence.

STUDY DESIGN

The Jerusalem Perinatal Study is a population-based cohort of all births to 41,206 residents of Western Jerusalem from 1964-76. Cancer incidence to 2004 was assessed by linkage of the cohort with the Israel Cancer Registry. Cox's proportional hazards models were constructed to estimate the hazard ratio for cancer among women who had had preeclampsia.

RESULTS

Preeclampsia was associated with a 1.23-fold increased risk of cancer at all sites, a 37% increased risk of breast cancer, and more than a doubling of ovarian cancer risk. Analysis by morphologic condition yielded significantly increased risks for malignancies that were classed as cystic mucinous and serous (relative risk, 1.96; 95% CI, 1.00-3.83) and for ductal, lobular, and medullary carcinomas (relative risk, 1.40; 95% CI, 1.07-1.83). No differential association was observed by sex of offspring.

CONCLUSION

Our study suggests that the previously described protective effect of preeclampsia on cancer is not universal.

Pregnancy weight gain is not associated with maternal or mixed umbilical cord estrogen and androgen concentrations

The association of maternal weight gain with serum hormone concentrations was explored in 75 women who had healthy, singleton pregnancies. Estradiol, estriol, estrone, androstenedione, testosterone, dehydroepiandrosterone (DHEA), and DHEA sulfate concentrations were measured both in maternal and mixed umbilical cord serum to assess hormone levels in both the maternal and fetal circulation at delivery. Our data show no association of maternal or cord steroid hormone concentrations with pregnancy weight gain. Increased exposure to steroid hormones, especially estrogens, during pregnancy has been hypothesized to play a role in subsequent breast cancer risk for both mother and female offspring. Our results are not consistent with an effect of pregnancy weight gain being mediated by this pathway as reflected by hormone concentrations at the end of pregnancy.