Human chorionic gonadotropin and alpha-fetoprotein concentrations in pregnancy and maternal risk of breast cancer: a nested case-control study

Prenatal Biochemical Screening and a Woman’s Long-Term Risk of Cancer: A Population-Based Cohort Study

Background

Some hormones measured in pregnancy are linked to certain hormone-sensitive cancers. We investigated whether routine serum screening in pregnancy is associated with a woman’s subsequent risk of hormone-sensitive cancer.

Methods

This population-based cohort study included women aged 12–55 years who underwent prenatal screening between 11 weeks + 0 days of gestation to 20 weeks + 6 days of gestation in Ontario, Canada, 1993–2011, where universal health care is available. The hazard ratio of newly diagnosed breast, ovarian, endometrial, and thyroid cancer—arising at 21 weeks + 0 days of gestation or thereafter—was estimated in association with an abnormally low (≤5th) or high (>95th) percentile multiple of the median (MoM) for alpha-fetoprotein (AFP), total human chorionic gonadotropin (hCG), unconjugated estriol, pregnancy-associated plasma protein A, and dimeric inhibin A.

Results

Among 677 247 pregnant women followed for a median of 11.0 years (interquartile range = 7.5–16.1), 7231 (1.07%) developed breast cancer, 515 (0.08%) ovarian cancer, 508 (0.08%) endometrial cancer, and 4105 (0.61%) thyroid cancer. In multivariable adjusted models, abnormally high hCG greater than the 95th percentile MoM was associated with a doubling in the risk of endometrial cancer (adjusted hazard ratio [aHR] = 1.98, 95% confidence interval [CI] = 1.33 to 2.95), and abnormally low AFP at the fifth percentile or less MoM conferred a moderately greater risk of thyroid cancer (aHR = 1.21, 95% CI = 1.07 to 1.38). Abnormally low pregnancy-associated plasma protein A at the fifth percentile or less MoM was not statistically significantly associated with breast cancer after multivariable adjustment (aHR = 1.19, 95% CI = 0.98 to 1.36).

Conclusions

Women with abnormally high levels of serum hCG or low AFP in early pregnancy may be at a greater future risk of certain types of hormone-sensitive cancers.

Maternal reproductive hormones and angiogenic factors in pregnancy and subsequent breast cancer risk

PURPOSE

Breast cancer risk associated with pregnancy characteristics may be mediated by maternal hormones or angiogenic factors.

METHODS

We conducted a prospective breast cancer case-control study among women in the Avon Longitudinal Study of Parents and Children (ALSPAC) and Norwegian Mother and Child Cohort Study (MoBa) related to maternal pregnancy prolactin (n = 254 cases and 374 controls), placental growth factor (PlGF, n = 252 and 371), soluble fms-like tyrosine kinase-1 (sFlt-1, n = 118 and 240) and steroid hormone concentrations (ALSPAC only, n = 173 and 171). Odds ratios (OR) and 95% confidence intervals (CI) for a 1 SD change in analytes were estimated using unconditional logistic regression with matching factors (cohort, mother's birth year, serum/plasma, blood collection timing) and gestational age.

RESULTS

Breast cancer ORs (95% CI) were 0.85 (0.51-1.43) for estradiol, 0.86 (0.67-1.09) for testosterone, 0.89 (0.71-1.13) for androstenedione, 0.97 (0.71-1.34) for hCG, 0.93 (0.75, 1.15) for prolactin, 1.00 (0.78-1.27) for PlGF and 1.91 (1.00-3.65 ALSPAC) and 0.94 (0.73-1.21 MoBa) for sFlt-1, and were similar adjusting for potential confounders. Results were similar by blood collection timing, parity, age at first birth or diagnosis, and time between pregnancy and diagnosis.

CONCLUSION

These data do not provide strong evidence of associations between maternal hormones or angiogenic factors with subsequent maternal breast cancer risk.

Hormone Levels in Pregnancy and Subsequent Risk of Maternal Breast and Ovarian Cancer: A Systematic Review

OBJECTIVE

Some maternal hormone levels in pregnancy are associated with a higher risk of breast and ovarian cancer. This study systematically assessed the association between blood hormone levels measured in pregnancy and future risk of these cancers.

METHODS

Two reviewers independently conducted a literature search of MEDLINE and EMBASE databases from January 1970 to August 2017. Studies were included that measured one or more serum hormone levels in pregnancy and later assessed for cancer. Cancer outcomes were considered by cancer type, each in relation to a specific maternal hormone.

RESULTS

Eleven studies were included, comprising a total of 57 967 women. The interval between pregnancy and cancer onset varied from 4.1 to 20.5 years. Elevated serum chorionic gonadotropin (two of four studies) and alpha fetoprotein (two of three studies) were each associated with a lower risk of maternal breast cancer, whereas elevated estrone levels suggested a higher risk (one of three studies). Elevated testosterone (one of one study) and androstenedione (one of one study) were each associated with a significantly greater risk of sex-cord stromal ovarian tumours. Higher serum 17-hydroxyprogesterone was associated with an increased risk of sex-cord stromal (one of one study) and epithelial (one of one study) ovarian cancer.

CONCLUSION

Observational studies suggest some degree of association between serum hormones measured in pregnancy and a woman's future risk of breast and ovarian cancer. More data are needed to determine sufficiently whether certain blood hormone levels measured in pregnancy are predictive of future cancer risk.

The importance of hCG in human endometrial adenocarcinoma and breast cancer

Human chorionic gonadotropin (hCG) is a peptide hormone which plays an important role during pregnancy. But its impact is not limited to pregnancy; it also influences tumor formation and metastatic outgrowth, especially in endometrial adenocarcinoma and breast cancer. This review summarizes what has been written in the literature about the role of hCG as a tumor marker in these 2 gynecological malignancies and also about the signal transduction pathways in which hCG is involved. HCG can, on the one hand, be a marker for the progression of a malignant disease, and on the other hand, it may be a point for therapeutical intervention, so further research into this molecule would be very much worthwhile.

Human Chorionic Gonadotropin and Breast Cancer

Breast cancer is well known as a malignancy being strongly influenced by female steroids. Pregnancy is a protective factor against breast cancer. Human chorionic gonadotropin (HCG) is a candidate hormone which could mediate this antitumoral effect of pregnancy. For this review article, all original research articles on the role of HCG in breast cancer were considered, which are listed in PubMed database and were written in English. The role of HCG in breast cancer seems to be a paradox. Placental heterodimeric HCG acts as a protective agent by imprinting a permanent genomic signature of the mammary gland determining a refractory condition to malignant transformation which is characterized by cellular differentiation, apoptosis and growth inhibition. On the other hand, ectopic expression of β-HCG in various cancer entities is associated with poor prognosis due to its tumor-promoting function. Placental HCG and ectopically expressed β-HCG exert opposite effects on breast tumorigenesis. Therefore, mimicking pregnancy by treatment with HCG is suggested as a strategy for breast cancer prevention, whereas targeting β-HCG expressing tumor cells seems to be an option for breast cancer therapy.

Early pregnancy sex steroids during primiparous pregnancies and maternal breast cancer: a nested case-control study in the Northern Sweden Maternity Cohort

BACKGROUND

Pregnancy and parity are associated with subsequent breast cancer risk. Experimental and epidemiologic data suggest a role for pregnancy sex steroid hormones.

METHODS

We conducted a nested case-control study in the Northern Sweden Maternity Cohort (1975-2007). Eligible women had provided a blood sample in the first 20 weeks of gestation during a primiparous pregnancy leading to a term delivery. The current study includes 223 cases and 417 matched controls (matching factors: age at and date of blood collection). Estrogen receptor (ER) and progesterone receptor (PR) status was available for all cases; androgen receptor (AR) data were available for 41% of cases (n = 92). Sex steroids were quantified by high-performance liquid chromatography tandem mass spectrometry. Odds ratios (ORs) and 95% confidence intervals were estimated using conditional logistic regression.

RESULTS

Higher concentrations of circulating progesterone in early pregnancy were inversely associated with ER+/PR+ breast cancer risk (OR_log2: 0.64 (0.41-1.00)). Higher testosterone was positively associated with ER+/PR+ disease risk (OR_log2: 1.57 (1.13-2.18)). Early pregnancy estrogens were not associated with risk, except for relatively high estradiol in the context of low progesterone (split at median, relative to low concentrations of both; OR: 1.87 (1.11-3.16)). None of the investigated hormones were associated with ER-/PR- disease, or with AR+ or AR+/ER+/PR+ disease.

CONCLUSIONS

Consistent with experimental models, high progesterone in early pregnancy was associated with lower risk of ER+/PR+ breast cancer in the mother. High circulating testosterone in early pregnancy, which likely reflects nonpregnant premenopausal exposure, was associated with higher risk of ER+/PR+ disease.

Human Chorionic Gonadotropin Does Not Correlate with Risk for Maternal Breast Cancer: Results from the Finnish Maternity Cohort

Human chorionic gonadotropin (hCG) is necessary for the maintenance of early pregnancy and promotes normal breast cell differentiation. Administered hCG reduces risk of carcinogen-induced breast cancer in animal models, and higher circulating hCG concentrations were associated with significantly lower long-term risk of breast cancer in a prior nested case-control study. In this study, we investigated early-pregnancy hCG concentrations and subsequent breast cancer risk. We conducted a nested case-control study with 1,191 cases and 2,257 controls (matched on age and date at blood collection) in the Finnish Maternity Cohort, a cohort with serum samples from 98% of pregnancies registered in Finland since 1983. This study included women with a serum sample collected early (<140 days gestation) in their first pregnancy resulting in a live, term birth. Breast cancer cases were identified via the Finnish Cancer Registry. Age at breast cancer diagnosis ranged from 22 to 58 years (mean: 41 years). hCG was measured using a solid-phase competitive chemiluminescence assay. Odds ratios (OR) were calculated using conditional logistic regression. We observed no association between hCG and breast cancer risk, overall [Quartile 4 vs. 1, OR, 1.14; 95% confidence interval (CI), 0.94-1.39], by estrogen and progesterone receptor status, or by ages at first-term birth or diagnosis. Associations did not differ by time between pregnancy and diagnosis (e.g., <5 years, OR_{Q4 vs. Q1}, 1.10; 95% CI, 0.64-1.89; ≥15 years, OR_{Q4 vs. Q1}, 1.36; 95% CI, 0.86-2.13; p_{heterogeneity} = 0.62). This large prospective study does not support an inverse relationship between early pregnancy serum hCG concentrations and breast cancer risk. Cancer Res; 77(1); 134-41. ©2016 AACR.

Relation between parity and pregnancy-related hormones and breast cancer control

SUMMARY 

Epidemiological research has indicated the beneficial effects of full-term pregnancy at an early age for a reduction in breast cancer risk. Experimental data have shown that pregnancy and pregnancy-related hormones, such as estrogen plus progesterone, estrogen alone and human chorionic gonadotropin, are involved in parity-induced protection. Pregnancy and short-duration treatment of a young host with pregnancy-related hormones to mimic the pregnancy environment provide mammary cancer protection by making cells refractory to carcinogenic stimuli and causing growth arrest and programmed cell death. Experimental data concerning pregnancy and pregnancy-related hormones are reviewed in relation to intrinsic subtypes of mammary cancer.

Free β-human chorionic gonadotropin, total human chorionic gonadotropin and maternal risk of breast cancer

BACKGROUND

We investigated whether the free β-human chorionic gonadotropin (free β-hCG) would provide additional information to that provided by total hCG alone and thus be useful in future epidemiological studies relating hCG to maternal breast cancer risk.

MATERIALS & METHODS

Cases (n = 159) and controls (n = 286) were a subset of our previous study within the Northern Sweden Maternity Cohort on total hCG during primiparous pregnancy and breast cancer risk.

RESULTS

The associations between total hCG (hazard ratio: 0.79; 95% CI: 0.49-1.27), free β-hCG (hazard ratio: 0.85; 95% CI: 0.33-2.18) and maternal risk of breast cancer were very similar in all analyses and mutual adjustment for either one had minor effects on the risk estimates.

CONCLUSION

In the absence of a reliable assay on intact hCG, total hCG alone can be used in epidemiological studies investigating hCG and breast cancer risk, as free β-hCG does not appear to provide any additional information.

Alpha fetoprotein can induce malignant transformation of liver cells and be used as a therapeutic target for hepatocellular carcinoma

Alpha-fetoprotein (AFP) is associated with the development of hepatocellular carcinoma (HCC) and widely used as a golden tumor marker for diagnosing HCC since the AFP gene is activated in the early stage of malignant transformation of liver cells. However, the molecular mechanisms responsible for the role of AFP in hepatocarcinogenesis remain poorly understood. Recently, we found that hepatitis B virus (HBV) preferentially induces the expression of AFP when triggering malignant transformation of hepatocytes, and AFP activates phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT) signaling by inhibiting the activity of phosphatase and tensin homolog deleted on chromosome ten (PTEN). Our results also indicated that AFP not only impedes all-trans retinoid acid receptor-β (RAR-β) regulated expression of target genes, but also blocks the transduction of apoptotic signaling by suppressing the activity of Caspase3. Inhibited expression of AFP is able to augment HCC sensitivity to tumor necrosis factor-related apoptosis-induced ligand (TRAIL) and all-trans retinoid acid. These data indicate that AFP can drive the malignant transformation of liver cells and antagonize apoptosis induced by agents for HCC. Taken together, these findings suggest that AFP may drive the malignant transformation of liver cells and can be used as a target for therapy of HCC.

Circulating levels of 25-hydroxyvitamin D and risk of breast cancer: a nested case-control study

Introduction

Experimental evidence suggests a protective role for circulating 25-hydroxyvitamin D (25(OH)D) in breast cancer development, but the results of epidemiological studies have been inconsistent.

Methods

We conducted a case-control study nested within two prospective cohorts, the New York University Women's Health Study and the Northern Sweden Mammary Screening Cohort. Blood samples were collected at enrollment, and women were followed up for breast cancer ascertainment. In total, 1,585 incident breast cancer cases were individually-matched to 2,940 controls. Of these subjects, 678 cases and 1,208 controls contributed two repeat blood samples, at least one year apart. Circulating levels of 25(OH)D were measured, and multivariate odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression.

Results

No association was observed between circulating levels of 25(OH)D and overall breast cancer risk (multivariate-adjusted model OR = 0.94, 95% CI = 0.76-1.16 for the highest vs. lowest quintile, p_trend = 0.30). The temporal reliability of 25(OH)D measured in repeat blood samples was high (intraclass correlation coefficients for season-adjusted 25(OH)D > 0.70). An inverse association between 25(OH)D levels and breast cancer risk was observed among women who were ≤ 45 years of age (OR_Q5-Q1 = 0.48, 95% CI = 0.30-0.79, p_trend = 0.01) or premenopausal at enrollment (OR_Q5-Q1 = 0.67, 95% CI = 0.48-0.92, p_trend = 0.03).

Conclusions

Circulating 25(OH)D levels were not associated with breast cancer risk overall, although we could not exclude the possibility of a protective effect in younger women. Recommendations regarding vitamin D supplementation should be based on considerations other than breast cancer prevention.

Dual effect of short interval between first and second birth on ductal breast cancer risk in Finland

OBJECTIVE

A short interval between the first and second birth was associated with an increased risk of advanced ductal breast cancer among women with 5+ childbirths in our previous study. We now evaluated the significance of this risk factor and its relation to the age at first birth among mothers with 2-4 children.

METHODS

The cohort of 190,949 Finnish women with 2-4 children comprised 3,834 women with ductal breast cancer diagnosed before 2009. Conditional logistic regression for case-control design nested within the cohort was used to estimate proportional hazard ratios (HR) associated with the birth interval. Controls were matched for age and number of children. Age at the first birth and the interval from the last birth to cancer were co-variables.

RESULTS

Among women with the first birth <30 years, the HR of advanced ductal breast cancer at 50+ years for a short (<1.5 years) versus long (>3 years) interval between the first and second birth was 0.48 (95% Confidence Interval 0.33-0.70). Among women with the first birth at 30+ years, the HR of this cancer type diagnosed before the age of 50 years for a short versus long interval between the first and second birth was 5.83 (95% CI 2.30-14.8).

CONCLUSION

The interval between first and second birth strongly influences the risk of ductal breast cancer. Because second pregnancy soon after the first one decreased the risk of ductal breast cancer in young primiparas but increased the risk in older primiparas, it is likely that in such circumstances second pregnancy continues the actions initiated by the first pregnancy/breast-feeding.

A population-based case-control study of fetal growth, gestational age, and maternal breast cancer

Fetal growth or gestational age in a woman's pregnancies may modify pregnancy-related breast cancer risk, yet studies of these exposures are few. The authors conducted a population-based case-control study among parous Michigan women aged ≤50 years using linked Michigan Cancer Registry (1985-2004) and Michigan livebirth records (1978-2004). Breast cancer cases (n = 7,591) were matched 1:4 to controls (n = 28,382) on maternal birth year and race. Using conditional logistic regression, the authors examined the associations of gestational age (in weeks) and fetal growth (defined using birth weight percentiles for gestational age) in first and last births with breast cancer risk. Having a small-for-gestational-age or large-for-gestational-age infant at a maternal first or last birth was not associated with breast cancer risk, but having a small-for-gestational-age infant at a last birth at ≥30 years modestly reduced risk: odds ratio = 0.82 (95% confidence interval: 0.68, 0.98). First delivery at <32 or >41 weeks also modestly reduced risk: odds ratio = 0.80 (95% confidence interval: 0.62, 1.04) or 0.92 (95% confidence interval: 0.85, 0.99), respectively. In the largest case-control study to date, fetal growth was not associated with overall breast cancer risk in women aged ≤50, and there was some evidence for reduced breast cancer risk for early or late gestational age in first births only.

Human chorionic gonadotropin in pregnancy and maternal risk of breast cancer

Full-term pregnancies are associated with long-term reductions in maternal risk of breast cancer, but the biological determinants of the protection are unknown. Experimental observations suggest that human chorionic gonadotropin (hCG), a major hormone of pregnancy, could play a role in this association. A case-control study (242 cases and 450 controls) nested within the Northern Sweden Maternity Cohort included women who had donated a blood sample during the first trimester of a first full-term pregnancy. Total hCG was determined on Immulite 2000 analyzer. Odds ratios (OR) and 95% confidence intervals (CI) were estimated through conditional logistic regression. Maternal breast cancer risk decreased with increasing hCG (upper tertile OR, 0.67; CI, 0.46-0.99), especially for pregnancies before age 25 (upper tertile OR, 0.41; CI, 0.21-0.80). The association diverged according to age at diagnosis: risk was reduced after age 40 (upper tertile OR, 0.60; CI, 0.39-0.91) and seemed to increase before age 40 (upper tertile OR, 1.78; CI, 0.72-4.38). Risk was reduced among those diagnosed 10 years or longer after blood draw (upper tertile OR, 0.60; CI, 0.40-0.90), but not so among those diagnosed within 10 years (upper tertile OR, 4.33; CI, 0.86-21.7). These observations suggest that the association between pregnancy hCG and subsequent maternal risk of breast cancer is modified by age at diagnosis. Although the hormone seems to be a determinant of the reduced risk around or after age 50, it might not confer protection against, or it could even increase the risk of, cancers diagnosed in the years immediately following pregnancy.

Maternal hormones during early pregnancy: a cross-sectional study

BACKGROUND

Little is known about correlates of first-trimester pregnancy hormones as in most studies maternal hormones have been measured later in gestation. We examined the associations of maternal characteristics and child sex with first-trimester maternal concentrations of four hormones implicated in breast cancer: human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP), insulin-like growth factor (IGF)-I, and IGF-II.

METHODS

About 338 serum samples donated to the Northern Sweden Maternity Cohort (NSMC), 1975-2001, during the first trimester of uncomplicated pregnancies, were analyzed for the hormones of interest as a part of a case-control study. The associations of maternal characteristics and child sex with hormone concentrations were investigated by correlation, general linear regression, and multivariate regression models.

RESULTS

In the first trimester, greater maternal age was inversely correlated with IGF-I and IGF-II. In comparison with women carrying their first child, already parous women had higher IGF-I but lower hCG. Greater maternal weight and smoking were inversely correlated with hCG. No differences in hormone levels by child sex were observed.

CONCLUSIONS

Our analyses indicated that potentially modifiable maternal characteristics (maternal weight and smoking) influence first-trimester pregnancy maternal hormone concentrations.

Endometrial responses to embryonic signals in the primate

The delicate interaction between an embryo and the uterus to initiate implantation and maintain pregnancy is one of the most elegant and fascinating interactions in human biology. Understanding the molecular events of embryo-maternal interaction is of interest to reproductive biologists, clinicians and couples affected by infertility. We have established the baboon as the non-human primate model for studying embryo implantation. Infusion of chorionic gonadotropin (CG), the major embryonic signal of primates, into the uterine cavity of normal cycling baboons during the window of receptivity induces a myriad of morphological, biochemical and molecular changes in the estrogen and progesterone primed endometrium. The luminal epithelium responds by forming plaques, the overall secretory function of the glandular epithelium increases and the stromal response is characterized by induction of alpha-smooth muscle actin (alphaSMA). Cross talk between ovarian and embryonic hormones is evidenced by the fact that these responses are inhibited upon treatment with a progesterone receptor antagonist. CG signals principally through the seven transmembrane LH/CG G-protein coupled receptor, and activates a mitogen activated protein kinase pathway in the endometrial epithelium that is unique and independent of all the classical signaling pathways. In the stromal compartment, CG both rescues stromal fibroblasts from their apoptotic demise and also differentiates them into the decidualized phenotype. We propose that stromal cell survival and differentiation is mediated by a critical modulator of cell fate, Notch-1. Thus, CG is an important embryonic signal which modulates communication between the embryo and the endometrium and induces changes that are critical to successful implantation.

Human chorionic gonadotropin (hCG) prevents the transformed phenotypes induced by 17 beta-estradiol in human breast epithelial cells

Human chorionic gonadotropin (hCG), a hormone produced during pregnancy, can elicit life-long refractoriness to carcinogenesis by differentiation of the breast epithelium. Human breast epithelial cells MCF-10F form tubules in collagen, mimicking the normal ductules. We have shown that 17 beta-estradiol (E2) alter the ductulogenic pattern of these cells. The effect of the recombinant hCG (rhCG) in vitro was evaluated on the transformation of MCF-10F induced by E2. MCF-10F cells were treated with 70 nM E2 alone or in combination with 50 IU/ml rhCG during 2 weeks, while the controls were treated with DMSO (the solvent in which E2 was dissolved) or rhCG alone. At the end of treatment, the cells were plated in type I collagen matrix (3D-cultures) for detecting 2 main phenotypes of cell transformation, namely the loss of ductulogenic capacity and the formation of solid masses. Although E2 significantly increased solid mass formation, this effect was prevented when MCF-10F cells were treated with E2 in combination with rhCG. Furthermore, E2 increased the main duct width (p < 0.001), and caused a disruption of the luminal architecture, whereas rhCG increased the length of the tubules (p < 0.001) and produced tertiary branching. In conclusion, rhCG was able to abrogate the transforming abilities of estradiol, and had the differentiating property by increasing the branching of the tubules formed by breast epithelial cells in collagen. These results further support our hypothesis, known as the terminal differentiation hypothesis of breast cancer prevention, that predicts that hCG treatment results in protection from tumorigenic changes by the loss of susceptible stem cells 1 through a differentiation to refractory stem cells 2 and increase differentiation of the mammary gland.

IGF-I during primiparous pregnancy and maternal risk of breast cancer

Previously, we reported that insulin-like growth factor (IGF)-I during early pregnancy is positively associated with maternal risk of breast cancer. To further explore this association, we designed a new study limited to women who donated a blood sample during their first pregnancy ending with childbirth. A case-control study was nested within the Northern Sweden Maternity Cohort in which repository since 1975, serum specimens remaining after early pregnancy screening for infectious diseases had been preserved. Study subjects were selected among women who donated a blood sample during the full-term pregnancy that led to the birth of their first child. Two hundred and forty-four women with invasive breast cancer were eligible. Two controls, matching the index case for age and date at blood donation were selected (n = 453). IGF-I was measured in serum samples on an Immulite 2000 analyzer. Conditional logistic regression was used to estimate odds ratios and 95% confidence intervals. A significant positive association of breast cancer with IGF-I was observed, with OR of 1.73 (95% CI: 1.14-2.63) for the top tertile, P < 0.009. Subgroup analyses did not indicate statistical heterogeneity of the association by ages at sampling and diagnosis or by lag time to cancer diagnosis, although somewhat stronger associations with risk were observed in women < or = age 25 at index pregnancy and for cases diagnosed within 15 years of blood donation. The results of the study add further evidence for an adverse effect of elevated IGF-I concentrations during early reproductive life on risk of breast cancer.

Angiogenic balance in pregnancy and subsequent breast cancer risk and survival: a population study

BACKGROUND

Women with a history of preeclampsia have reduced breast cancer risk. Because preeclampsia is characterized by an imbalance in angiogenic factors, we assessed pregnancy levels of placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and soluble endoglin (s-endoglin) and subsequent breast cancer risk.

METHODS

In a case-control study among 26,744 pregnant women, we compared angiogenic factors between 145 women who later developed invasive breast cancer and 400 controls. The angiogenic factors were determined with ELISA in blood samples collected in weeks (median) 10, 23, and 35 of the baseline pregnancy.

RESULTS

Concentrations of PlGF, sFlt-1, and s-endoglin did not differ between women who later developed breast cancer and control women, and odds ratios across quartiles of each factor did not indicate any association in blood samples from gestational week 10, 23, or 35. During pregnancy, there was a general increase in each angiogenic factor, but degree of increase from one sampling period to the next was not associated with later breast cancer risk. Among cases, 22 of 145 died from breast cancer during 10 years of follow-up, but there was no consistent indication that angiogenic factors measured in pregnancy up to several years before diagnosis were associated with case fatality.

CONCLUSIONS

The results of this nested case-control study, based on blood samples collected up to three time points during pregnancy, and subsequent cancer follow-up, do not provide any evidence that pregnancy levels of PlGF, sFlt-1, and s-endoglin are associated with breast cancer risk later in life.