Preeclampsia and breast cancer: The influence of birth characteristics

Causal effects of hypertensive disorders of pregnancy on future gynecologic tumors: A two-sample Mendelian randomization study

BACKGROUND

Numerous observational studies have investigated the potential link between hypertensive disorders of pregnancy (HDPs) and the subsequent risks of gynecologic tumors, yet the findings have been inconsistent. In this study, we utilized Mendelian randomization (MR) approach to assess the influence of HDPs on the future risks of ovarian, cervical, endometrial, and breast cancer and uterine fibroids, controlling for confounding factors.

METHODS

The genome-wide association studies (GWAS) summary data relevant to HDPs was obtained from the FinnGen databases (10,736 cases and 136,325 controls). Gynecologic tumor outcomes were extracted from the IEU Open GWAS project and UK Biobank (47,690 cases and 1, 092,073 controls). The inverse variance weighted (IVW) approach was selected as the principal method for MR analysis, supplemented by MR-Egger, weighted median, weighted model, simple model methods, MR pleiotropy residual sum and outlier (MR-PRESSO) test, and leave-one-out method. Multivariate MR (MVMR) analysis was conducted after adjusting systolic blood pressure (SBP), body mass index (BMI) and type 2 diabetes mellitus (T2DM).

RESULTS

Our univariate MR analysis (UVMR) results revealed no significant relationship between HDPs and the risks of ovarian cancer (odds ratio [OR] = 0.924, p = 0.360), cervical cancer (OR = 1.230, p = 0.738), endometrial cancer (OR = 1.006, p = 0.949), uterine fibroids (OR = 1.155, p = 0.158), and breast cancer (OR = 0.792, p = 0.241) by IVW test. Similar results were observed in gestational hypertension and preeclampsia/eclampsia. Additionally, our study detected neither heterogeneity nor pleiotropy. MVMR analysis also provided no evidence of a causal association between HDPs and common gynecologic tumors after adjusting SBP, BMI, and T2DM.

CONCLUSION

We discovered no causal relationship between HDPs and ovarian, cervical, endometrial, breast cancer, and uterine fibroids in European populations. However, present analysis did not explore the effect of HDPs on the subtypes of gynecologic tumors across varied ethnic populations, which may require additional research.

Women with preeclampsia may have reduced risk of breast cancer: a meta-analysis of cohort studies with 7.8 million participants

This review pooled data from the literature to examine the association between preeclampsia (PE) and subsequent risk of breast cancer in women. Cohort studies published in the databases of PubMed, Embase, Scopus, and Web of Science up to 18 July 2023 were searched. Adjusted data were pooled to obtain the risk ratio (RR). Eleven studies with 15 cohorts and a cumulative sample size of 7,838,693 women were included. Meta-analysis of all studies demonstrated a reduced risk of breast cancer in women with PE as compared to those without PE (RR: 0.89 95% CI: 0.83, 0.95 p < 0.001 I2 = 50%). Follow-up ranged from 8 to 29.2 years. Results did not change during sensitivity analysis. Outcomes varied on subgroup analysis based on location, study type, data extraction method, incidence of breast cancer, and follow-up. To conclude, women with PE may have a reduced risk of breast cancer later in life. However, the risk reduction is minimal and may not have much clinical significance. The evidence is also limited by high inter-study heterogeneity and lack of adjustment of all possible confounders.

Hypertensive conditions of pregnancy, preterm birth, and premenopausal breast cancer risk: a premenopausal breast cancer collaborative group analysis

PURPOSE

Women with preeclampsia are more likely to deliver preterm. Reports of inverse associations between preeclampsia and breast cancer risk, and positive associations between preterm birth and breast cancer risk are difficult to reconcile. We investigated the co-occurrence of preeclampsia/gestational hypertension with preterm birth and breast cancer risk using data from the Premenopausal Breast Cancer Collaborative Group.

METHODS

Across 6 cohorts, 3096 premenopausal breast cancers were diagnosed among 184,866 parous women. We estimated multivariable hazard ratios (HR) and 95% confidence intervals (CI) for premenopausal breast cancer risk using Cox proportional hazards regression.

RESULTS

Overall, preterm birth was not associated (HR 1.02, 95% CI 0.92, 1.14), and preeclampsia was inversely associated (HR 0.86, 95% CI 0.76, 0.99), with premenopausal breast cancer risk. In stratified analyses using data from 3 cohorts, preterm birth associations with breast cancer risk were modified by hypertensive conditions in first pregnancies (P-interaction = 0.09). Preterm birth was positively associated with premenopausal breast cancer in strata of women with preeclampsia or gestational hypertension (HR 1.52, 95% CI: 1.06, 2.18), but not among women with normotensive pregnancy (HR = 1.09, 95% CI: 0.93, 1.28). When stratified by preterm birth, the inverse association with preeclampsia was more apparent, but not statistically different (P-interaction = 0.2), among women who did not deliver preterm (HR = 0.82, 95% CI 0.68, 1.00) than those who did (HR = 1.07, 95% CI 0.73, 1.56).

CONCLUSION

Findings support an overall inverse association of preeclampsia history with premenopausal breast cancer risk. Estimates for preterm birth and breast cancer may vary according to other conditions of pregnancy.

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.

Preeclampsia and cancer risk in women in later life: a systematic review and meta-analysis of cohort studies

IMPORTANCE

Results of this work may provide some guidance for subsequent ovarian cancer screening in women with preeclampsia and provide new directions for future studies.

OBJECTIVE

This study investigated the difference in cancer risk between women with preeclampsia and women with a normal pregnancy.

EVIDENCE REVIEW

Electronic databases, namely PubMed, Embase, and the Cochrane Library, were searched for relevant studies from database inception to February 4, 2021. The results are expressed as risk ratios (RRs).

FINDINGS

The study included 13 cohort studies comprising 5,254,150 participants. The difference in the total cancer risk between the control and preeclampsia groups was statistically nonsignificant. However, breast cancer (BC) risk was lower in the preeclampsia group (RR = 0.88, 95% confidence interval (CI) = 0.83-0.93; I2 = 57.2%). A subgroup analysis stratified by reproductive factors demonstrated that BC risk in the preeclampsia population decreased in parous women (RR = 0.79, 95% CI = 0.72-0.87; I2 = 0%), women with full-term pregnancies (RR = 0.79, 95% CI = 0.75-0.84; I2 = 0%), and women with increasing parity. Furthermore, BC risk reduced in women with preeclampsia regardless of their menopausal status and the sex of their offspring.

CONCLUSIONS AND RELEVANCE

Overall, women with preeclampsia have a decreased BC risk and increased ovarian cancer risk compared with the normal population. A subgroup analysis stratified by reproductive factors demonstrated that BC risk decreased in the preeclampsia population in parous women, women with full-term pregnancies, and women with increasing parity regardless of their menopausal status and the sex of their offspring.

Assessment of All-Cause Cancer Incidence Among Individuals With Preeclampsia or Eclampsia During First Pregnancy

IMPORTANCE

Preeclampsia or eclampsia (preeclampsia/eclampsia) during pregnancy induces major physiological changes and may be associated with specific cancer occurrences in later life. The current data regarding the association between preeclampsia/eclampsia and cancer are heterogeneous, and cancer risk after preeclampsia/eclampsia could be different depending on the organ. These uncertainties warrant reexamination of the association between preeclampsia/eclampsia and the risk of cancer overall and by specific cancer type.

OBJECTIVE

To evaluate the risk of cancer, overall and by type, after preeclampsia/eclampsia during a first pregnancy.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study used data from the French hospital discharge database to identify all female individuals who had a pregnancy-associated hospitalization between January 1, 2010, and December 31, 2019. To allow a minimum of 2 years for the detection of medical history, individuals with a first detected pregnancy before January 1, 2012, were excluded, as were those with a cancer-associated hospitalization before or during their first detected pregnancy. Exposures, comorbidities, and occurrences of cancer were evaluated using data from the medico-administrative registers of hospitalizations in private and public French hospitals. Cox proportional hazards models were used to analyze cancer risk according to the occurrence of preeclampsia/eclampsia during first pregnancy.

EXPOSURES

Preeclampsia/eclampsia-associated hospitalization during the first detected pregnancy.

MAIN OUTCOMES AND MEASURES

The primary outcome was the incidence of cancer, including myelodysplastic or myeloproliferative diseases, after a first pregnancy with and without preeclampsia/eclampsia.

RESULTS

After exclusions, a total of 4 322 970 female individuals (mean [SD] age at first detected pregnancy, 29.6 [6.2] years) with and without preeclampsia/eclampsia during their first pregnancy were included. Of those, 45 523 individuals (1.1%) were diagnosed with preeclampsia/eclampsia during their first detected pregnancy. The maximum follow-up was 8 years, during which 29 173 individuals (0.7%) were diagnosed with cancer. No significant difference in overall cancer incidence was found between those with and without preeclampsia/eclampsia during their first pregnancy (adjusted hazard ratio [AHR], 0.94; 95% CI, 0.84-1.05). Preeclampsia/eclampsia was associated with an increase in the risk of myelodysplastic syndromes or myeloproliferative diseases (AHR, 2.43; 95% CI, 1.46-4.06) and kidney cancer (AHR, 2.19; 95% CI, 1.09-4.42) and a decrease in the risk of breast cancer (AHR, 0.79; 95% CI, 0.62-0.99) and cervical cancer (AHR, 0.75; 95% CI, 0.58-0.96).

CONCLUSIONS AND RELEVANCE

In this study, a history of preeclampsia/eclampsia during first pregnancy was associated with an increase in the incidence of myelodysplastic or myeloproliferative diseases and kidney cancer and a decrease in the incidence of cervical and breast cancers. These associations might reflect an underlying common factor among preeclampsia/eclampsia and these pathologies and/or an association between preeclampsia/eclampsia and the development of these cancers.

Cancer and Cardiovascular Risk in Women With Hypertensive Disorders of Pregnancy Carrying a Common IGF1R Variant

OBJECTIVE

To evaluate the impact of insulin-like growth factor 1 receptor variant rs2016347 on the risk for breast and nonbreast cancers and cardiovascular disease in women with a history of hypertensive disorders of pregnancy (HDP).

PATIENTS AND METHODS

This retrospective cohort study included all parous women in the UK Biobank with prior rs2016347 genotyping (N=204,155), with enrollment taking place from March 2006 to July 2010. History of HDP was self-reported, and outcomes included breast and all nonbreast cancers, hospital diagnoses of hypertension and cardiovascular disease, and direct blood pressure measurements.

RESULTS

Women with previous HDP had a higher risk for future hypertension and cardiovascular diagnoses, increased blood pressures, and lower risk for breast cancer compared with women without HDP, consistent with prior studies. Hazard ratios for all nonbreast cancers were unchanged. However, when taking genotype into account, HDP-positive women carrying at least 1 thymine (T) allele of rs2016347 had a lower risk for nonbreast cancer (hazard ratio, 0.59; 95% CI, 0.37 to 0.92; P=.02) and lower systolic blood pressure (-2.08±0.98 mm Hg; P=.03) compared with women with the guanine/guanine (GG) genotype with positive evidence of interaction (HDP:T allele) for both outcomes; P=.04 and P=.03, respectively.

CONCLUSION

Women who experience HDP and carry a T allele of rs2016347 have 41% lower risk for developing nonbreast cancer and a lower systolic blood pressure of 2.08 mm Hg when compared with those with the GG genotype, suggesting a possible role of the insulin-like growth factor 1 axis for both cardiovascular and cancer risk in women with HDP.

Hypertensive Disorders of Pregnancy (HDP) and the Risk of Common Cancers in Women: Evidence from the European Prospective Investigation into Cancer (EPIC)-Norfolk Prospective Population-Based Study

Simple Summary

One in ten pregnancies is complicated with high blood pressure. Whilst the association between high blood pressure during pregnancy and cardiovascular disease in later life is well-established, its association with cancer is less so. We aimed to determine the association between hypertensive disorders of pregnancy (HDP) and common cancers in a UK population-based longitudinal study. No statistically significant association was found between HDP and the odds of future cancer, and independent site-specific cancers of breast, colorectal, lung, ovarian and endometrial cancers in a UK-based general practice-derived population. Current research underlining HDP and cancer risk is limited to specific populations only. Future work in different populations is required, focusing on complex genetic and hormonal factors involved in these conditions.

Abstract

Purpose: The purpose was to determine the association between HDP and cancer in a UK cohort. Methods: Between 1993 and 1997, participants from the EPIC-Norfolk cohort attended baseline health-checks and completed questionnaires, where a history of HDP was collected. Incident cancer cases were identified through NHS record linkage until March 2016. Univariable and multivariable logistic regression analyses were employed to determine the association between HDP and odds of cancer, with adjustment for potential confounders including co-morbidities, sociodemographic, lifestyle and reproductive factors. Results: 13,562 women were included after excluding prevalent cancer cases and women with no pregnancies. 2919 (21.5%) reported HDP and 2615 incident cancers occurred during mean follow up of 19 years. Median age (IQR) at baseline for incident cancer was 60.8 (±14.8) years. Among incident cancer cases, 578 (22.1%) had HDP. In multivariable analyses, HDP had odds ratio (OR) 1.06; 95% CI 0.95–1.18 for incident cancer. The ORs (95% CIs) for common site-specific cancers including breast, colorectal, lung, ovarian and endometrial cancers were 1.06 (0.88–1.28), 1.15 (0.92–1.45), 0.96 (0.68–1.35), 1.30 (0.93–1.83) and 1.16 (0.80–1.67). Conclusion: We found no association between HDP and cancer risk. Further studies are required to confirm and account for any underlying genetic factors involved in pregnancy-related exposures and cancer risk.

Pregnancy Hypertension and a Commonly Inherited IGF1R Variant (rs2016347) Reduce Breast Cancer Risk by Enhancing Mammary Gland Involution

Background

Terminal duct lobular units (TDLUs) are the anatomic sites of breast cancer initiation, and breast tissue involution resulting in lower TDLU counts has been associated with decreased breast cancer risk. The insulin-like growth factor (IGF) pathway plays a role in breast involution, and systemic changes in this developmental pathway occur with hypertensive disorders of pregnancy (HDP), which have also been associated with lower breast cancer risk, especially in women carrying a functional variant of IGF1R SNP rs2016347. We proposed that this breast cancer protective effect might be explained by increased breast tissue involution.

Materials and Methods

We conducted a retrospective cohort study utilizing the Komen Tissue Bank, which collects breast tissue core biopsies from women without a history of breast cancer. Eighty white non-Hispanic women with a history of HDP were selected along with 120 nonexposed participants, and after genotyping for rs2016347, TDLU parameters were histologically measured blinded to participant characteristics from fixed biopsy sections.

Results

Stratified models by HDP status demonstrated that among HDP+ participants, those carrying two T alleles of rs2016347 had a decrease in TDLU counts of 53.2% when compared to those with no T alleles (p=0.049). Trend analysis demonstrated a multiplicative decrease in counts of 31.6% per T allele (p=0.050). Although no statistically significant interaction was seen between HDP status and T alleles, interaction terms showed increasingly negative values reaching a p value of 0.124 for HDP × 2T alleles.

Conclusions

The observed statistically significant decrease in TDLU counts signifies increased breast epithelial involution in women with prior HDP who inherited the TT genotype of IGF1R SNP rs2016347. The increasing degree of breast involution with greater rs2016347 T allele copy number is consistent with the known progressive reduction in IGF1R expression in breast and other normal tissues.

Long-term effect of pregnancy-related factors on the development of endometrial neoplasia: A nationwide retrospective cohort study

Objective

By identifying pregnancy-related risk factors for endometrial neoplasia, women’s risk of developing this disease after childbirth can be predicted and high-risk women can be screened for early detection.

Methods

Study data from women who gave birth in Korea in 2007 were collected from the Korea National Health Insurance (KNHI) claims database between 2007 and 2015. The adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the development of endometrial neoplasia were estimated by multivariate Cox proportional hazards models.

Results

Data from 386,614 women were collected for this study. By 2015, 3,370 women from the initial cohort had been diagnosed with endometrial neoplasia secondary to delivery. Multivariate Cox proportional hazards regression revealed that preeclampsia (HR 1.55, 95% CI 1.29, 1.86), advanced maternal age (≥ 35; HR 1.52, 95% CI 1.39, 1.66), multifetal pregnancy (HR 1.81, 95% CI 1.46, 2.23), multiparity (HR 1.16, 95% CI 1.08, 1.24), cesarean section (HR 1.15, 95% CI 1.07, 1.23) and delivery of a large-for-gestational-age infant (HR 1.19, 95% CI 1.02, 1.39) were independent risk factors for future endometrial neoplasia. The risk for endometrial neoplasia increased as the number of risk factors increased (risk factors ≥3: HR 2.11, 95% CI 1.86–2.40).

Conclusion

This study showed that six pregnancy-related factors—advanced maternal age, multiparity, multifetal pregnancy, cesarean section, delivery of a large-for-gestational-age infant, and preeclampsia—are positively correlated with future development of endometrial neoplasia, including endometrial hyperplasia or cancer. Close observation and surveillance are warranted to enable early diagnosis of endometrial diseases, including endometrial cancer after pregnancy in high-risk women. However, due to unavailability of clinical information, many clinical/epidemiological factors can become confounders. Further research is needed on factors associated with the risk of endometrial neoplasia.

Subsequent risk of cancer among women with a history of placental abruption

BACKGROUND

Placentation is characterized by extensive cell proliferation and neovascularization, which is similar to the processes observed in the development of cancer. Nonetheless, little is known about the relation between abnormal placentation, such as placental abruption, and cancer.

MATERIAL AND METHODS

Data on women with placental abruption in a singleton pregnancy between 1971 and 2005 (n = 7804) were collected from the Finnish Hospital Discharge Registry and the Finnish Medical Birth Registry. The cohort was then linked with the Finnish Cancer Registry records until the end of 2013. Standardized incidence ratios (SIRs) were calculated for different cancers by dividing the observed numbers of cancers by those expected. The expected numbers were based on national cancer incidence rates.

RESULTS

During follow-up, 597 cancers were found among women with a history of placental abruption. The overall risk of cancer was not increased (SIR 0.95, 95% CI 0.88-1.02). However, the history of placental abruption was associated with an increased risk of lung cancer (SIR 1.51, 95% CI 1.05-2.10) and thyroid cancer (SIR 1.47, 95% CI 1.04-2.02). A decreased risk was found for breast cancer (SIR 0.85, 95% CI 0.75-0.96). The risk of rectal cancer was also decreased, although these numbers were small (SIR 0.49, 95% CI 0.20-1.01).

CONCLUSIONS

Overall, the risk of lung cancer was increased, and the risk of breast cancer decreased, in women with a history of placental abruption. These observations can be explained to some extent by risk factors or risk markers for placental abruption. The increased risk of thyroid cancer may be explained by surveillance bias.

De vuelta a la clínica. Métodos I. Diseños de investigación. Mayor calidad de información, mayor certeza a la respuesta

Research designs refer to the way information is obtained and are limited by ethical, economic and temporal viability. Research designs are standardized strategies to reduce biases, which in the architectural model of research are identified in the baseline state, the maneuver and the outcome; hence, there are no specific designs for each question. The design with the lowest probability of bias is the clinical trial, followed by cohort and case-control studies and, finally, by cross-sectional surveys. Among the main characteristics that give merit to research designs are the following: population inquiry, which refers to the situation of the population in relation to the clinical course/natural history of the disease; the maneuver, or action that is expected to modify the baseline state, which can be observational or experimental; follow-up, or documented monitoring that is given to each subject, which can be longitudinal or cross-sectional; and directionality, which can prolective or retrolective and refers to the timing of data collection for research purposes. It will always be better having a valuable question, even when answered with a design with higher risk of bias, than a question that is irrelevant or has no applicability.

Maternal breast cancer risk in relation to birthweight and gestation of her offspring

BACKGROUND

Parity and age at first pregnancy are well-established risk factors for breast cancer, but the effects of other characteristics of pregnancies are uncertain and the literature is inconsistent.

METHODS

In a cohort of 83,451 parous women from the general population of the UK, which collected detailed information on each pregnancy and a wide range of potential confounders, we investigated the associations of length of gestation and birthweight of offspring in a woman's pregnancies with her breast cancer risk, adjusting for a full range of non-reproductive as well as reproductive risk factors unlike in previous large studies.

RESULTS

Gestation of the first-born offspring was significantly inversely related to the risk of pre-menopausal breast cancer (p trend = 0.03; hazard ratio (HR) for 26-31 compared with 40-41 weeks, the baseline group, = 2.38, 95% confidence interval (CI) 1.26-4.49), and was borderline significantly related to risk of breast cancer overall (p trend = 0.05). Risk was significantly raised in mothers of high birthweight first-born (HR for breast cancer overall = 1.53, 95% CI 1.06-2.21 for ≥ 4500 g compared with 3000-3499 g, the baseline group). For gestation and birthweight of most recent birth, there were no clear effects. Analyses without adjustment for confounders (other than age) gave similar results.

CONCLUSIONS

Our data add to evidence that short gestation pregnancies may increase the risk of breast cancer, at least pre-menopausally, perhaps by hormonal stimulation and breast proliferation early in pregnancy without the opportunity for the differentiation that occurs in late pregnancy. High birthweight first pregnancies may increase breast cancer risk, possibly through the association of birthweight with oestrogen and insulin-like growth factor 1 levels.

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.

Preeclampsia and scleroderma: a prospective nationwide analysis

INTRODUCTION

In a preliminary case-control study, women with scleroderma more frequently reported having had hypertensive complications during pregnancy compared with healthy women.

MATERIAL AND METHODS

To prospectively investigate this possible association, we conducted a nation-wide cohort analysis of a major hypertensive complication during pregnancy, namely preeclampsia, and later scleroderma. Analyses were based on Danish register-based birth and hospital contact data on preeclampsia and scleroderma. We followed 778,758 women from time of giving birth between 1978 and 2010 to end of follow-up, emigration, death, or scleroderma diagnosis, whichever occurred first. The association was evaluated by incidence rate ratios, obtained in Poisson regression models.

RESULTS

We report that preeclampsia is associated with a 69% significantly increased risk of later developing scleroderma.

CONCLUSIONS

Though these findings do not impact clinical care directly, the association of preeclampsia with scleroderma underscores the significant relation of preeclampsia and other adverse pregnancy outcomes with later disease in women and should be included in patient counseling and education.

Inherited factors contribute to an inverse association between preeclampsia and breast cancer

Background

Preeclampsia is frequently linked to reduced breast cancer risk. However, little is known regarding the underlying genetic association and the association between preeclampsia and mammographic density.

Methods

This study estimates the incidence rate ratios (IRRs) of breast cancer in patients with preeclampsia, when compared to women without preeclampsia, using Poisson regression models in two cohorts of pregnant women: a Swedish nationwide cohort (n = 1,337,934, 1973–2011) and the Karolinska Mammography Project for Risk Prediction of Breast Cancer (KARMA, n = 55,044, 1958–2015). To identify the genetic association between preeclampsia and breast cancer, we used logistic regression models to calculate the odds ratios (ORs) of preeclampsia in sisters of breast cancer patients, and in women with different percentiles of breast cancer polygenic risk scores (PRS). Linear regression models were used to estimate the mammographic density by preeclampsia status in the KARMA cohort.

Results

A decreased risk of breast cancer was observed among patients with preeclampsia in both the nationwide (IRR = 0.90, 95% CI = 0.85; 0.96) and KARMA cohorts (IRR = 0.75, 95% CI = 0.61; 0.93). Women with high breast cancer PRS and sisters of breast cancer patients had a lower risk of preeclampsia (OR = 0.89, 95% CI = 0.83; 0.96). Mammographic density was lower in women with preeclampsia compared to women without preeclampsia (-2.04%, 95% CI = -2.65; -1.43). Additionally, among sisters in the KARMA cohort (N = 3500), density was lower in sisters of patients with preeclampsia compared to sisters of women without preeclampsia (-2.76%, 95% CI = -4.96; -0.56).

Conclusion

Preeclampsia is associated with reduced risk of breast cancer and mammographic density. Inherited factors contribute to this inverse association.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0930-6) contains supplementary material, which is available to authorized users.

Preeclampsia and maternal risk of breast cancer: a meta-analysis of cohort studies

BACKGROUND

Pregnancy-related hypertensive disorders, including preeclampsia (PE) and pregnancy-induced hypertension (PIH), may influence the maternal risk of breast cancer. However, results of the cohort studies were inconsistent.

METHODS

An updated meta-analysis of cohort studies was performed to evaluate the association between PE, PIH and maternal breast cancer incidence. Relevant studies were identified via searching of PubMed and Embase databases. A random effect model was applied to synthesize the results. Stratified analyses were performed to evaluate the potential influence of parity, gender of offspring, and study design on the association between PE and maternal breast cancer incidence.

RESULTS

Ten cohort studies with 2,417,899 pregnant women were included. Maternal risk of breast cancer was not significantly affected by PE (risk ration [RR] = 0.93, 95% confidence interval [CI]: 0.82-1.06, p = .27), or PIH (RR = 0.95, 95% CI: 0.81-1.12, p = .54). Interestingly, PE was associated with significantly lowered maternal incidence of breast cancer in women who give birth to male offspring (RR = 0.79, p < .01), and in those of prospective cohort studies (RR = 0.87, p < .01). However, no significant association between PE and maternal breast cancer was detected in primiparous women, those who gave birth to female offspring, or those of retrospective cohorts.

CONCLUSIONS

Current evidence did not support a conclusive association between PE, PIH and the maternal risk of breast cancer. Gender of the offspring may influence the association between PE and maternal breast cancer incidence.

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.

History of Gestational Diabetes Mellitus and Risk of Incident Invasive Breast Cancer among Parous Women in the Nurses' Health Study II Prospective Cohort

Background: Type II diabetes is associated with breast cancer in epidemiologic studies. Pregnancy also modifies breast cancer risk. We hypothesized that women with a history of gestational diabetes mellitus (GDM), which shares pathogenesis and risk factors with type II diabetes, would have greater invasive breast cancer risk than parous women without a history of GDM.Methods: We conducted a prospective analysis among parous women in the Nurses' Health Study II, with mean age 35 years in 1989. Multivariate Cox proportional hazards models were used to compare risks of incident invasive breast cancer in women with and without a history of GDM.Results: Among 86,972 women studied, 5,188 women reported a history of GDM and 2,377 developed invasive breast cancer (100 with history of GDM, 2,277 without GDM) over 22 years of prospective follow-up. History of GDM was inversely associated with incident invasive breast cancer [HR, 0.68; 95% confidence interval (CI), 0.55-0.84; P = 0.0004], compared with no history of GDM, after adjustment for body mass index, reproductive history, and other breast cancer risk factors. Findings were similar by menopausal status, although observed person-time was predominantly premenopausal (premenopausal: HR, 0.73; 95% CI, 0.56-0.96; P = 0.03; postmenopausal: HR, 0.63; 95% CI, 0.43-0.92; P = 0.02). Restricting to women undergoing mammography screening modestly attenuated the relationship (HR, 0.74; 95% CI, 0.57-0.96; P = 0.02).Conclusions: Among a large cohort of U.S. women, history of GDM was not associated with an elevated risk of subsequent invasive breast cancer.Impact: Our findings highlight the need to further investigate GDM's role in breast cancer development. Cancer Epidemiol Biomarkers Prev; 26(3); 321-7. ©2016 AACR.

Long-term impact of preeclampsia on maternal endometrial cancer risk

BACKGROUND

Endometrial cancer is mainly dependent on oestrogen exposure. Preeclampsia has shown to reduce oestrogen levels hence preeclampsia may affect later endometrial cancer risk.

METHODS

We conducted a case-control study of 523 Danish women with endometrial cancer and 52 299controls during 1978-2010. The association between preeclampsia and later endometrial cancer was evaluated overall and according to preeclampsia onset and type of endometrial cancer in conditional logistic regression models.

RESULTS

We observed no overall association between preeclampsia and endometrial cancer risk (OR=1.11 (95% CI 0.68-1.81)). This was true for all endometrial cancer subtypes. In an analysis of preeclampsia onset, however, we report a markedly increased risk of endometrial cancer following early-onset preeclampsia (OR=2.64 (95% CI 1.29-5.38)).

CONCLUSIONS

Although we report no obvious association between preeclampsia and endometrial cancer, studying the subset of early-onset preeclampsia may prove fruitful in further understanding the aetiology of endometrial cancer.

Hypertensive disorders of pregnancy and subsequent risk of solid cancer--A nationwide cohort study

Women with hypertensive disorders of pregnancy (HDP) have higher levels of antiangiogenic growth factors during pregnancy than women with normotensive pregnancies. Since angiogenesis is necessary for solid cancer growth and spread, we hypothesized that women with a history of HDP might have a reduced risk of solid cancers (cancers other than lymphomas, hematologic cancers and nonmelanoma skin cancers) later in life. In a register-based cohort study of 1.08 million women giving birth at least once between 1978 and 2011, we used Cox regression to estimate hazard ratios (HRs) comparing solid cancer rates for women with and without a history of HDP. In this cohort, 68,236 women (6.3%) had ≥1 pregnancy complicated by HDP and 42,236 women (3.9%) developed solid tumors during follow-up. A history of HDP was not associated with a clinically meaningful reduction in the overall rate of solid cancer (HR 0.96, 95% confidence interval 0.92-1.00), regardless of HDP severity or time since HDP, nor was there a general tendency toward reduced solid cancer rates across organ sites. A history of HDP was only significantly associated with decreased rates of breast and lung cancers and with increased rates of endometrial and urinary tract cancers. Overall, our results do not support the hypothesis that women with a history of HDP have a reduced overall risk of solid cancer due to a persistent post-HDP antiangiogenic state or an innate tendency toward antiangiogenesis. Observed associations with specific cancers may instead be due to other pregnancy-related mechanisms or to residual/unmeasured confounding.