Effects of oral contraceptives on breast epithelial proliferation

Estetrol: From Preclinical to Clinical Pharmacology and Advances in the Understanding of the Molecular Mechanism of Action

Estetrol (E4) is the most recently described natural estrogen. It is produced by the human fetal liver during pregnancy and its physiological function remains unclear. E4 is the estrogenic component of a recently approved combined oral contraceptive. It is also in development for use as menopausal hormone therapy. In the context of these developments, the pharmacological activity of E4, alone or in combination with a progestin, has been extensively characterized in preclinical models as well as in clinical studies in women of reproductive age and postmenopausal women. Despite the clinical benefits, the use of oral estrogens for contraception or menopause is also associated with unwanted effects, such as an increased risk of breast cancer and thromboembolic events, due to their impact on non-target tissues. Preclinical and clinical data for E4 point to a tissue-specific activity and a more selective pharmacological profile compared with other estrogens, including a low impact on the liver and hemostasis balance. This review summarizes the characterization of the pharmacological properties of E4 as well as recent advances made in the understanding of the molecular mechanisms of action driving its activity. How the unique mode of action and the different metabolism of E4 might support its favorable benefit-risk ratio is also discussed.

Effects of Estradiol/Micronized Progesterone vs. Conjugated Equine Estrogens/Medroxyprogesterone Acetate on Breast Cancer Gene Expression in Healthy Postmenopausal Women

Recent studies suggest estradiol (E₂)/natural progesterone (P) confers less breast cancer risk compared with conjugated equine estrogens (CEE)/synthetic progestogens. We investigate if differences in the regulation of breast cancer-related gene expression could provide some explanation. This study is a subset of a monocentric, 2-way, open observer-blinded, phase 4 randomized controlled trial on healthy postmenopausal women with climacteric symptoms (ClinicalTrials.gov; EUCTR-2005/001016-51). Study medication was two 28-day cycles of sequential hormone treatment with oral 0.625 mg CEE and 5 mg of oral medroxyprogesterone acetate (MPA) or 1.5 mg E₂ as percutaneous gel/day with the addition of 200 mg oral micronized P. MPA and P were added days 15-28/cycle. Material from two core-needle breast biopsies in 15 women in each group was subject to quantitative PCR (Q-PCR). The primary endpoint was a change in breast carcinoma development gene expression. In the first eight consecutive women, RNA was extracted at baseline and after two months of treatment and subjected to microarray for 28856 genes and Ingenuity Pathways Analysis (IPA) to identify risk factor genes. Microarray analysis showed 3272 genes regulated with a fold-change of >±1.4. IPA showed 225 genes belonging to mammary-tumor development function: 198 for CEE/MPA vs. 34 for E₂/P. Sixteen genes involved in mammary tumor inclination were subject to Q-PCR, inclining the CEE/MPA group towards an increased risk for breast carcinoma compared to the E₂/P group at a very high significance level (p = 3.1 × 10^-8, z-score 1.94). The combination of E₂/P affected breast cancer-related genes much less than CEE/MPA.

The progesterone-receptor modulator, ulipristal acetate, drastically lowers breast cell proliferation

PURPOSE

The proliferation of breast epithelial cells increases during the luteal phase of the menstrual cycle, when they are exposed to progesterone, suggesting that ulipristal acetate, a selective progestin-receptor modulator (SPRM), may reduce breast cell proliferation with potential use in breast cancer chemoprevention.

METHODS

Women aged 18-39 were randomized 1:1 to ulipristal 10-mg daily or to a combination oral contraceptive (COC) for 84 days. Participants underwent a breast biopsy and breast MRI at baseline and at end of study treatment. Proliferation of breast TDLU cells was evaluated by Ki67 immunohistochemical stain. We evaluated the breast MRIs for background parenchymal enhancement (BPE). All slides and images were masked for outcome evaluation.

RESULTS

Twenty-eight treatment-compliant participants completed the study; 25 of whom had evaluable Ki67 results at baseline and on-treatment. From baseline to end of treatment, Ki67 % positivity (Ki67%+) decreased a median of 84% in the ulipristal group (N = 13; 2-sided p (2p) = 0.040) versus a median increase of 8% in the COC group (N = 12; 2p = 0.85). Median BPE scores decreased from 3 to 1 in the ulipristal group (p = 0.008) and did not decrease in the COC group.

CONCLUSION

Ulipristal was associated with a major decrease in Ki67%+ and BPE. Ulipristal would warrant further investigation for breast cancer chemoprevention were it not for concerns about its liver toxicity. Novel SPRMs without liver toxicity could provide a new approach to breast cancer chemoprevention.

TRIAL REGISTRATION

NCT02922127, 4 October 2016.

Associations of Oral Contraceptives with Mammographic Breast Density in Premenopausal Women

BACKGROUND

We investigated the associations of oral contraceptives (OC) with percent breast density (PD), absolute dense area (DA), nondense area (NDA), and a novel image intensity variation (V) measure in premenopausal women.

METHODS

This study included 1,233 controls from a nested case-control study within Nurses' Health Study II cohort. Information on OCs was collected in 1989 and updated biennially. OC use was defined from the questionnaire closest to the mammogram date. PD, DA, and NDA were measured from digitized film mammograms using a computer-assisted thresholding technique; the V measure was obtained with a previously developed algorithm measuring the SD of pixel values in the eroded breast region. Generalized linear regression was used to assess associations between OCs and density measures (square root-transformed PD, DA, and NDA, and -untransformed V).

RESULTS

OC use was not associated with PD [current vs. never: β = -0.06; 95% confidence interval (CI), -0.37-0.24; past vs. never: β = 0.10; 95% CI, -0.09-0.29], DA (current vs. never: β = -0.20; 95% CI -0.59-0.18; past vs. never: β = 0.13; 95% CI, -0.12-0.39), and NDA (current vs. never: β = -0.19; 95% CI, -0.56-0.18; past vs. never: β = -0.01; 95% CI, -0.28-0.25). Women with younger age at initiation had significantly greater V-measure (<20 years vs. never: β = 26.88; 95% CI, 3.18-50.58; 20-24 years vs. never: β = 20.23; 95% CI, -4.24-44.71; 25-29 years vs. never: β = 2.61; 95% CI -29.00-34.23; ≥30 years vs. never: β = 0.28; 95% CI, -34.16-34.72, P _trend = 0.03).

CONCLUSIONS

Our findings suggest that an earlier age at first OC use was associated with significantly greater V.

IMPACT

These findings could guide decisions about the age for OC initiation.

The Impact of Progestin-only Contraception on Adolescents with Macromastia

Progestin-only contraception has become increasingly popular among adolescents. However, patients, parents, and providers share concerns regarding the potential impact that progestin-only contraception may have on breast growth. We sought to explore the impact of progestin-only contraception on breast hypertrophy and symptomatology in adolescents with macromastia.

METHODS

Patients between the ages of 12 and 21 years undergoing reduction mammaplasty were prospectively assessed for baseline and postoperative breast symptomatology and medication use. The medical records of female controls within the same age range were retrospectively reviewed.

RESULTS

A total of 378 participants with macromastia and 378 controls were included in analyses. A higher proportion of controls used progestin-only methods compared with participants with macromastia (28.0% versus 5.3%, P < 0.001). The most commonly prescribed methods were the depot medroxyprogesterone acetate injection (31.0%), levonorgestrel-containing intrauterine device (31.0%), and subdermal implant (26.2%). Patients with macromastia who used progestin-only contraception had a greater amount of breast tissue resected during reduction mammaplasty (P = 0.04), reported greater musculoskeletal pain (P = 0.008), and were roughly 500% more likely to experience breast pain (odds ratio, 4.94; 95% confidence interval, 1.58-15.47; P = 0.005) than those with macromastia who never used hormonal contraception.

CONCLUSIONS

Adolescents with macromastia who use progestin-only contraception may have greater breast hypertrophy and worse breast and musculoskeletal pain. When appropriate, providers may wish to consider other contraception methods for patients who are at-risk for breast hypertrophy or those who suffer from macromastia-related symptoms.

Progestogen addition with low-dose levonorgestrel intrauterine system in menopausal hormone treatment gives less normal breast tissue proliferation than oral norethisterone acetate or medroxyprogesterone acetate

Background The impact of hormones on the development of breast cancer is despite extensive studies, incompletely understood. Combined estrogen-progestogen treatment augments the risk for breast cancer beyond that of estrogen alone, according to numerous studies. The role of breast cell proliferation as a promoter in the development and growth of breast cancer is well recognized. Materials and methods Seventy-nine patients from three randomised trials were subject to a re-analysis of breast cell proliferation: (1) 22 women received continuous combined treatment with oral estradiol (E2) 2 mg/norethisterone acetate (NETA) 1 mg once daily for 3 months. (2) Thirty-seven women received 2 months of sequential treatment with oral conjugated equine estrogens (CEE) 0.625 mg daily combined with medroxyprogesterone acetate (MPA) 5 mg for 14/28 days of each cycle. (3) Twenty women received oral estradiol-valerate (E2V) 2 mg daily combined with levonorgestrel (LNG) intrauterine system (IUS), 20 μg/24 h for 2 months. Fine needle aspiration (FNA) (studies 1 and 3) and core needle biopsy (CNB) (study 2) were used for the assessment of breast cell proliferation. Results There were no baseline proliferation differences, but at the end of treatment there was a highly significant between-group difference for E2V/LNG IUS versus the other two groups (p = 0.0025). E2/NETA and CEE treatments gave a 4-7-old increase in proliferation during treatment (p = 0.04) and (p = 0.007), respectively, which was absent in the E2V/LNG group, showing a significant correlation with insulin-like growth factor binding protein-3 (IGFBP-3) serum levels. Conclusion E2V in combination with very low serum concentrations of LNG in the IUS gives no increase in proliferation in the normal breast.

Dehydroepiandrosterone and/or its metabolites: possible androgen receptor antagonistic effects on digitized mammographic breast density in normal breast tissue of postmenopausal women

Background Androgens, notably testosterone inhibit breast cell proliferation and negative correlations between free testosterone (fT) and breast cell proliferation as well as mammographic density have been described. Dehydroepiandrosterone (DHEA) is reported to be a partial androgen antagonist in breast tumor cells in vitro. Our aim was to investigate if circulating DHEA had any effects on the association between circulating fT and mammographic density in vivo in the normal postmenopausal breast. Methods We measured visual and digitized mammographic density and serum DHEA, testosterone, sex-hormone-binding globulin and calculated fT in 84 healthy untreated postmenopausal women. Results Significant negative correlations between fT and both visual and digitized mammographic density were strengthened when the median DHEA level decreased from 10.2 to 8.6 nmol/L. Thereafter, correlations became weaker again probably due to decreasing fT levels and/or sample size. There were no correlations between mammographic density and DHEA, at any of the DHEA concentration ranges studied. Serum levels of fT and DHEA were positively correlated. Conclusion Our findings demonstrate that circulating DHEA and/or its metabolites counteract the inhibitory action of fT on mammographic breast density.

Exploration of Racial Differences in Reproductive Factors for Breast Cancer among Women aged 55-74

Background Reproductive factors have been well-documented risk factors for breast cancer. Few studies have examined whether the associations between reproductive factors and breast cancer differed across races/ethnicities. Methods We analyzed a sub-sample (70, 734) of the Prostate, Lung, Colorectal, and Ovarian (PLCO) dataset. Participants with valid baseline questionnaire and without breast cancer at enrollment were included into analysis. We stratified the participants into subgroups based on their races/ethnicities then estimated the effects of the reproductive factors on breast cancer within each group using Cox-proportion regression models. Results Oral contraceptive use (HR=1.09, 95% confidence interval or CI=1.01, 1.18), advanced age at natural menopause (HR=1.25, 95% CI=1.06, 1.49) were associated with increased risk of breast cancer in non-Hispanic Caucasians group only. Long term use of menopausal hormone therapy (more than five years) was associated with increased risk of breast cancer in both of the non-Hispanic Caucasian (HR=1.44, 95% CI=1.31, 1.59) group and the non-Hispanic Asian/Pacific Islander (HR=1.98, 95% CI=1.23, 3.20) group, but not in other race/ethnic groups. Hispanics who tried to become pregnant for a year or more had increased risk of breast cancer (HR=2.60, 95% CI=1.05, 6.46) than their counterparts without difficulty in getting pregnancy. In addition, surgery induced menopause was found to be a protective factor for breast cancer in non-Hispanic Caucasian (HR=0.88, 95% CI=0.79, 0.98) group only.

Conclusions We concluded that different races/ethnicities had different breast cancer related reproductive risk factors. Non-Hispanic Caucasians had the most breast cancer related reproductive risk factors, while the minorities had none or few breast cancer related reproductive risk factors and among these few factors only 1 was also risk factor for non-Hispanic Caucasians.

Oral Contraceptive Use May Modulate Global Genomic DNA Methylation and Promoter Methylation of APC1 and ESR1

Background:

There are challenging reports in the public health sphere regarding associations between oral contraceptive (OC) use and cancer risk.

Methods:

To evaluate possible effects of OCs on cancer susceptibility, we quantified of global 5-methyl cytosine (5-mC) levels and assessed methylation patterns of CpG islands of two key tumor suppressor genes, APC1 and ESR1, in serum of users by enzyme-linked immunosorbent assay and methylation specific PCR methods, respectively.

Results:

Our results indicated that OCs significantly decrease the level of global DNA methylation in users relative to control non-users. However, our data revealed no significant differences between CpG island methylation patterns for ESR1 and APC1 in healthy control and OC-treated women. However, we did find a trend for hypermethylation of both tumor suppressor genes in OC users.

Conclusion:

Our data suggest that the level of 5-mC but not individual CpG island patterns is significantly influenced by OCs in our cross-section of adult users.

Effects of chlorinated biphenyls and metabolites on human uterine myocyte proliferation

Uterine myometrial cells are responsive to sex steroids, which could make them susceptible to actions of endocrine disrupting environmental contaminants such as some PCBs. The aim of this investigation was to identify possible effects of some chlorinated biphenyls (CBs) and their metabolites on myometrial cell proliferation. Myometrial cells obtained from women in both phases of the menstrual cycle and from pregnant women were grown in vitro and exposed to CB 101, CB 118, 3' -MeSO2CB 101, 4'-MeSO2-CB 101, 4-OH-CB 107, 17 β-estradiol, progesterone, ethinylestradiol or levonorgestrel.

The proliferative activity was studied by a BrdU assay. Myometrial cell cultures originating from pregnant women exhibited decreased proliferation in response to 3'-MeSO 2-CB 101, 4'-MeSO2-CB 101 and 4-OH-CB 107. Estradiol, a combination of 1 nM 17β-estradiol and 10 nM progesterone, ethinylestradiol and levonorgestrel also reduced the proliferation of the myometrial cells, regardless of whether the cells were collected from either of the menstrual cycle phases or from pregnant women. To our knowledge this study is the first to demonstrate that some CBs affect the proliferative activity of human uterine myocytes. Human & Experimental Toxicology (2007) 26, 801— 809

Breast tissue composition and its dependence on demographic risk factors for breast cancer: non-invasive assessment by time domain diffuse optical spectroscopy

BACKGROUND

Breast tissue composition is recognized as a strong and independent risk factor for breast cancer. It is a heritable feature, but is also significantly affected by several other elements (e.g., age, menopause). Nowadays it is quantified by mammographic density, thus requiring the use of ionizing radiation. Optical techniques are absolutely non-invasive and have already proved effective in the investigation of biological tissues, as they are sensitive to tissue composition and structure.

METHODS

Time domain diffuse optical spectroscopy was performed at 7 wavelengths (635-1060 nm) on 200 subjects to derive their breast tissue composition (in terms of water, lipid and collagen content), blood parameters (total hemoglobin content and oxygen saturation level), and information on the microscopic structure (scattering amplitude and power). The dependence of all optically-derived parameters on age, menopausal status, body mass index, and use of oral contraceptives, and the correlation with mammographic density were investigated.

RESULTS

Younger age, premenopausal status, lower body mass index values, and use of oral contraceptives all correspond to significantly higher water, collagen and total hemoglobin content, and lower lipid content (always p < 0.05 and often p < 10-4), while oxygen saturation level and scattering parameters show significant dependence only on some conditions. Even when age-adjusted groups of subjects are compared, several optically derived parameters (and in particular always collagen and total hemoglobin content) remain significantly different.

CONCLUSIONS

Time domain diffuse optical spectroscopy can probe non-invasively breast tissue composition and physiologic blood parameters, and provide information on tissue structure. The measurement is suitable for in vivo studies and monitoring of changes in breast tissue (e.g., with age, lifestyle, chemotherapy, etc.) and to gain insight into related processes, like the origin of cancer risk associated with breast density.

A case-control analysis of oral contraceptive use and breast cancer subtypes in the African American Breast Cancer Epidemiology and Risk Consortium

Introduction

Recent oral contraceptive (OC) use has been consistently associated with increased risk of breast cancer, but evidence on specific breast cancer subtypes is sparse.

Methods

We investigated recency and duration of OC use in relation to molecular subtypes of breast cancer in a pooled analysis of data from the African American Breast Cancer Epidemiology and Risk Consortium. The study included 1,848 women with estrogen receptor-positive (ER+) breast cancer, 1,043 with ER-negative (ER-) breast cancer (including 494 triple negative (TN) tumors, which do not have receptors for estrogen, progesterone, and human epidermal growth factor 2), and 10,044 controls. Multivariable polytomous logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for exposure categories relative to never use, controlling for potential confounding variables.

Results

OC use within the previous 5 years was associated with increased risk of ER+ (OR 1.46, 95% CI 1.18 to 1.81), ER- (OR 1.57, 95% CI 1.22 to 1.43), and TN (OR 1.78, 95% CI 1.25 to 2.53) breast cancer. The risk declined after cessation of use but was apparent for ER+ cancer for 15 to 19 years after cessation and for ER- breast cancer for an even longer interval after cessation. Long duration of use was also associated with increased risk of each subtype, particularly ER-.

Conclusions

Our results suggest that OC use, particularly recent use of long duration, is associated with an increased risk of ER+, ER-, and TN breast cancer in African American women. Research into mechanisms that explain these findings, especially the association with ER- breast cancer, is needed.

Recent oral contraceptive use by formulation and breast cancer risk among women 20 to 49 years of age

Previous studies of oral contraceptives and breast cancer indicate that recent use slightly increases risk, but most studies relied on self-reported use and did not examine contemporary oral contraceptive formulations. This nested case-control study was among female enrollees in a large U.S. integrated health care delivery system. Cases were 1,102 women ages 20 to 49 years diagnosed with invasive breast cancer from 1990 to 2009. Controls were randomly sampled from enrollment records (n = 21,952) and matched to cases on age, year, enrollment length, and medical chart availability. Detailed oral contraceptive use information was ascertained from electronic pharmacy records and analyzed using conditional logistic regression, ORs, and 95% confidence intervals (CI). Recent oral contraceptive use (within the prior year) was associated with an increased breast cancer risk (OR, 1.5; 95% CI, 1.3-1.9) relative to never or former OC use. The association was stronger for estrogen receptor-positive (ER(+); OR, 1.7; 95% CI, 1.3-2.1) than estrogen receptor-negative (ER(-)) disease (OR, 1.2, 95% CI, 0.8-1.8), although not statistically significantly different (P = 0.15). Recent use of oral contraceptives involving high-dose estrogen (OR, 2.7; 95% CI, 1.1-6.2), ethynodiol diacetate (OR, 2.6; 95% CI, 1.4-4.7), or triphasic dosing with an average of 0.75 mg of norethindrone (OR, 3.1; 95% CI, 1.9-5.1; Pheterogeneity compared with using other oral contraceptives = 0.004) was associated with particularly elevated risks, whereas other types, including low-dose estrogen oral contraceptives, were not (OR, 1.0; 95% CI, 0.6-1.7). Our results suggest that recent use of contemporary oral contraceptives is associated with an increased breast cancer risk, which may vary by formulation. If confirmed, consideration of the breast cancer risk associated with different oral contraceptive types could impact discussions weighing recognized health benefits and potential risks.

Risk-benefit assessment of the combined oral contraceptive pill in women with a family history of female cancer

INTRODUCTION

Oral contraceptive pills (OCPs) are the most frequently used form of effective, reversible contraception among women of childbearing potential. In the average risk population, OCPs may offer a protective benefit against ovarian, endometrial and colorectal malignancies. In women at high risk for breast, ovarian, endometrial or colorectal malignancies, the risk-benefit profile is less well studied.

AREAS COVERED

In this article, we review pertinent literature on the use of OCPs in patients with genetic susceptibilities due to mutations in BRCA1, BRCA2 or mismatch repair genes implicated in hereditary nonpolyposis colorectal cancer as well as those with a strong family history of malignancies associated with these syndromes.

EXPERT OPINION

For women at high risk for ovarian, endometrial and/or colorectal malignancies due to genetic susceptibilities or a strong family history, the possibility of chemoprevention with OCPs may be an attractive option; however, the potential increase in breast cancer, although small, must be considered in clinical decision-making. The ultimate decision to use OCPs in a high-risk woman should be based on a consideration of her specific genetic risk, her age, her reproductive plans and her willingness to consider surgical prophylaxis options.

Oral contraceptives and breast cancer risk overall and by molecular subtype among young women

BACKGROUND

Evidence suggests that recent oral contraceptive (OC) use is associated with a small increased breast cancer risk; yet risks associated with contemporary OC preparations and by molecular subtype are not well characterized.

METHODS

We conducted a population-based case-control study of invasive breast cancer among women ages 20 to 44 residing in the Seattle-Puget Sound area from 2004 to 2010 (985 cases and 882 controls). We collected information on contraceptive use and participant characteristics via an in-person interview. Multivariable-adjusted logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Lifetime duration of OC use for ≥ 15 years was associated with an increased breast cancer risk (OR, 1.5; 95% CI, 1.1-2.2). Current OC use (within 1 year of reference date) for ≥ 5 years was associated with an increased risk (OR, 1.6; 95% CI, 1.1-2.5) and there were no statistically significant differences in risk by OC preparation. Risk magnitudes were generally greater among women ages 20 to 39, and for estrogen receptor-negative (ER(-)) and triple-negative breast cancer (current use for ≥ 5 years among ages 20-39: ER(-) OR, 3.5; 95% CI, 1.3-9.0; triple-negative OR, 3.7; 95% CI, 1.2-11.8), although differences between groups were not statistically significant.

CONCLUSIONS

Long-term use of contemporary OCs and current use for ≥ 5 years was associated with an increased breast cancer risk among women ages 20 to 44. Risk may be greater among younger women and for ER(-) and triple-negative breast cancer, but these findings require confirmation.

IMPACT

Continued surveillance and pooled analyses of OC use and breast cancer risk by molecular subtype are needed as OC preparations evolve.

Timing of oral contraceptive use and the risk of breast cancer in BRCA1 mutation carriers

It is not clear if early oral contraceptive use increases the risk of breast cancer among young women with a breast cancer susceptibility gene 1 (BRCA1) mutation. Given the benefit of oral contraceptives for the prevention of ovarian cancer, estimating age-specific risk ratios for oral contraceptive use and breast cancer is important. We conducted a case-control study of 2,492 matched pairs of women with a deleterious BRCA1 mutation. Breast cancer cases and unaffected controls were matched on year of birth and country of residence. Detailed information about oral contraceptive use was collected from a routinely administered questionnaire. Conditional logistic regression was used to estimate the odds ratios (OR) and 95 % confidence intervals (CI) for the association between oral contraceptive and breast cancer, by age at first use and by age at diagnosis. Among BRCA1 mutation carriers, oral contraceptive use was significantly associated with an increased risk of breast cancer for women who started the pill prior to age 20 (OR 1.45; 95 % CI 1.20-1.75; P = 0.0001) and possibly between ages 20 and 25 as well (OR 1.19; 95 % CI 0.99-1.42; P = 0.06). The effect was limited to breast cancers diagnosed before age 40 (OR 1.40; 95 % CI 1.14-1.70; P = 0.001); the risk of early-onset breast cancer increased by 11 % with each additional year of pill use when initiated prior to age 20 (OR 1.11; 95 % CI 1.03-1.20; P = 0.008). There was no observed increase for women diagnosed at or after the age of 40 (OR 0.97; 95 % CI 0.79-1.20; P = 0.81). Oral contraceptive use before age 25 increases the risk of early-onset breast cancer among women with a BRCA1 mutation and the risk increases with duration of use. Caution should be taken when advising women with a BRCA1 mutation to take an oral contraceptive prior to age 25.

Percutaneous estradiol/oral micronized progesterone has less-adverse effects and different gene regulations than oral conjugated equine estrogens/medroxyprogesterone acetate in the breasts of healthy women in vivo

Gene expression analysis of healthy postmenopausal women in a prospective clinical study indicated that genes encoding for epithelial proliferation markers Ki-67 and progesterone receptor B mRNA are differentially expressed in women using hormone therapy (HT) with natural versus synthetic estrogens. Two 28-day cycles of daily estradiol (E2) gel 1.5 mg and oral micronized progesterone (P) 200 mg/day for the last 14 days of each cycle did not significantly increase breast epithelial proliferation (Ki-67 MIB-1 positive cells) at the cell level nor at the mRNA level (MKI-67 gene). A borderline significant beneficial reduction in anti-apoptotic protein bcl-2, favouring apoptosis, was also seen followed by a slight numeric decrease of its mRNA. By contrast, two 28-day cycles of daily oral conjugated equine estrogens (CEE) 0.625 mg and oral medroxyprogesterone acetate (MPA) 5 mg for the last 14 days of each cycle significantly increased proliferation at both the cell level and at the mRNA level, and significantly enhanced mammographic breast density, an important risk factor for breast cancer. In addition, CEE/MPA affected around 2,500 genes compared with just 600 affected by E2/P. These results suggest that HT with natural estrogens affects a much smaller number of genes and has less-adverse effects on the normal breast in vivo than conventional, synthetic therapy.

Lowering oral contraceptive norethindrone dose increases estrogen and progesterone receptor levels with no reduction in proliferation of breast epithelium: a randomized trial

BACKGROUND

This study was conducted to compare breast epithelial-cell proliferation and estrogen and progesterone receptor levels in women taking one of two oral contraceptives (OCs) containing the same dose of estrogen but different doses of the progestin norethindrone (NET).

STUDY DESIGN

Thirty-three women were randomly assigned 1:1 to one of two OCs with 35-mcg ethinylestradiol (EE2) but different doses of NET - 1 or 0.4 mg. At the end of the active pill phase of the third OC cycle, a breast biopsy was performed and the percentages of epithelial cells of the terminal duct lobular units were measured for Ki67 (MIB1), progesterone receptors A and B (PRA and PRB, respectively), and estrogen receptor α (ERα).

RESULTS

The biopsies from 27 women had sufficient epithelium for analysis. The percentages of cells positive for PRA, PRB and ERα were approximately double with the lower progestin dose (PRA: p=.041; PRB: p=.030; ERα: p=.056). The Ki67 percentage was not reduced with the lower progestin dose (12.5% for 0.4-mg NET vs. 7.8% for 1.0-mg NET).

CONCLUSIONS

The increase in PRA-, PRB- and ERα-positive cells with the 60% lower progestin dose OC appears likely to account for its failure to decrease breast-cell proliferation. This breast-cell proliferation result is contrary to that predicted from the results of lowering the medroxyprogesterone acetate dose in menopausal hormone therapy.

Oral contraceptive use and breast cancer: a prospective study of young women

BACKGROUND

Previous studies convincingly showed an increase in risk of breast cancer associated with current or recent use of oral contraceptives from the 1960s to 1980s. The relation of contemporary oral contraceptive formulations to breast cancer risk is less clear.

METHODS

We assessed lifetime oral contraceptive use and the specific formulations used among 116,608 female nurses ages 25 to 42 years at enrollment in 1989, and subsequently updated this information every 2 years. We related this information to risk of breast cancer up to June 1, 2001.

RESULTS

During 1,246,967 person-years of follow-up, 1,344 cases of invasive breast cancer were diagnosed. Past use of any oral contraceptive was not related to breast cancer risk [multivariate relative risk (RR), 1.12; 95% confidence interval 0.95-1.33]. Current use of any oral contraceptive was related to a marginally significant higher risk (multivariate RR, 1.33; 95% CI, 1.03-1.73). One specific formulation substantially accounted for the excess risk: the RR for current use of triphasic preparations with levonorgestrel as the progestin was 3.05 (95% CI, 2.00-4.66; P < 0.0001).

CONCLUSIONS

Current use of oral contraceptives carries an excess risk of breast cancer. Levonorgestrel used in triphasic preparations may account for much of this elevation in risk.

IMPACT

Different oral contraceptive formulations might convey different risks of breast cancer; ongoing monitoring of these associations is necessary as oral contraceptive formulations change.

Mechanisms for differential effects between natural progesterone and synthetic progestogens on normal breast tissue

Both epidemiological studies and experimental data on normal breast tissue suggest increased cancer risk, proliferation and mammographic breast density (MD) during hormone therapy (HT) containing synthetic progestogens in traditional doses, and the relative risk or RR is approximately 1.5–3 (for women treated vs. untreated with the above therapies), proliferation levels of normal breast epithelial cells of around 10% and increase in MD in up to around 50% of women during treatment. Dose-response relationships have been inferred by correlations between progestogens as levonorgestrel, norethisterone acetate and medroxyprogesterone acetate on the one hand and proliferation and/or MD on the other hand, and of indications of lower relative risk of breast cancer with modern low or ultra-low dose HT. In contrast, natural progesterone endogenously during the menstrual cycle has a weak effect and exogenous estrogen in combination with oral micronized progesterone in HT has shown to yield an indifferent effect on proliferation. Furthermore, in epidemiological studies such as the French E3N cohort, these combinations have not shown any risk increase for breast cancer for at least 5 years of treatment. Experimental data supporting or not supporting the view that the main proliferative mechanism for natural progesterone is through binding to its nascent progesterone receptors is discussed as well as the pros and cons that the non-physiological higher proliferation levels induced by synthetic progestogens is mainly mediated through interaction with potent growth factors and their paracrine and/or cell signaling pathways.

Regulation of Msx2 Gene Expression by Steroid Hormones in Human Nonmalignant and Malignant Breast Cancer Explants Cultured in Vitro

Muscle segment homeobox genes, which regulate developmental programs and are expressed in embryonic and adult tissue, play a role in development of some malignancies. There are no reports on the expression of these families of genes in breast cancer tissue. The aim of this study was to compare expression of Msx2 gene in breast cancer of different genotypes as well as in surrounding nonmalignant tissues. Explants obtained during surgery were divided according to their sex steroid receptor status determined by immunocytochemistry. Four explants obtained from malignant and nonmalignant tissue of each individual patient were incubated in a control medium or with the addition of progesterone (10(-7) M) alone, estradiol 17 beta (10(-5) M) or both. The relative level of Msx2 transcripts was evaluated by a semiquantitative RT-PCR and cell proliferation by Alamar Blue test. Results of RT-PCR analysis showed that the relative expression of Msx2 gene depended on the presence of ER/PR receptors both in nonmalignant and malignant tissues Relative amount of Msx2 mRNA was the highest in surrounding nonmalignant ER+/PR- and ER-/PR+ tissue, whereas in ER-/PR- and ER+/PR+ tissue it was 1.4-1.6-fold lower. Tumorigenesis led to about a twofold decrease in the relative amount of Msx2 mRNA except for ER+/PR+ immunophenotype, where no changes were observed. Addition of estradiol or progesterone to the culture of ER-/PR- type tissue explants did not change significantly the relative amount of Msx2 gene mRNA. An opposite effect was observed in ER+/PR- type of tissue. Addition of estradiol alone, or estradiol and progesterone together to tissue culture explants decreased two to three fold the relative amount of Msx2 gene mRNA in both, malignant and surrounding tissues. Progesterone alone had no effect on Msx2 gene expression in this type of tissue. The most complicated regulation was observed in ER+/PR+ type of tissue. Culture of tissue explants supplemented with estradiol significantly increased the relative amount of Msx2 gene mRNA in the surrounding tissue. Progesterone enhanced the stimulatory effect of estradiol in surrounding tissues but not in the malignant tissue. Increased expression of Msx2 correlated with an increased proliferation in ER-/PR- and ER+/PR+ types, but not in ER+/PR- type of tissues. In conclusion, obtained results provide evidence that estrogen affects Msx2 gene expression. Significant changes in the relative amount of Msx2 gene mRNA and lack of canonical ERE element in 5'-upstream sequence of this gene suggest that regulation takes place indirectly probably by protein-protein interaction. The decrease in the relative amount of Msx2 gene mRNA in ER+/PR- type tumor suggests that progesterone also affects Msx2 gene expression by an indirect mechanism(s).

Breast cancer and hormonal therapy

Valid evidence from randomized-controlled trials indicates that breast cancer risk is increased with combined estrogen/progestogen use and that such treatment implies a risk greater than that of estrogen alone. Overall, risk estimates from observational studies are somewhat higher than in randomized-controlled trials but remain modest as compared with other risk factors even after long-term treatment. For combined estrogen/progestogen therapy, risk increases gradually to reach statistical significance after 4 to 5 years. Apart from its many beneficial health effects, the safety data for use of estrogen alone are quite reassuring. The only justifications for progestogen addition are for bleeding control and endometrial protection. At present, there are several new therapeutic compounds and concepts in development, which hold promise to provide both endometrial protection and breast safety.

Effects of pre- and postmenopausal use of exogenous hormones on receptor content in normal human breast tissue: a randomized study

OBJECTIVE

To examine the effects of exposure to endogenous and exogenous hormones on estrogen receptor-alpha (ERalpha) and progesterone receptor (PR) levels in normal human breast tissue.

METHODS

In a randomized study of women scheduled for mammary reduction plasty (n = 81), ERalpha and PR content in breast parenchyma was analyzed in premenopausal (n = 49) and postmenopausal (n = 16) women. Premenopausal women were randomized to surgery in the follicular or luteal phase of the menstrual cycle or after oral contraceptive treatment for 2 months. Postmenopausal women were randomized to sequential or estrogen-only therapy for 2 months prior to surgery.

RESULTS

ERalpha content was higher in parous than in nulliparous (p = 0.009) premenopausal women and displayed a positive association with age (r(s) = 0.51, p = 0.0002). Compared with premenopausal women in the follicular phase, postmenopausal women had higher ERalpha content (p = 0.040) whereas premenopausal women on oral contraception had lower ERalpha (p = 0.048) and PR (p = 0.007) content. Smokers had lower PR content than non-smokers (p = 0.02).

CONCLUSION

In the present study ERalpha content was higher in parous than in non-parous women and associated with premenopausal age. Short-term oral contraceptives yielded lower ERalpha and PR contents. Postmenopausal estrogen/progestogen combined therapy yielded lower PR content than estrogen-only therapy.

Associations between serum testosterone levels, cell proliferation and progesterone receptor content in normal and malignant breast tissue in postmenopausal women

Progestogens and progesterone receptors (PR) may play an important role in increased breast proliferation following combined estrogen/progestogen hormone therapy, while androgens may counteract this effect. In 50 untreated healthy postmenopausal women and 48 untreated postmenopausal breast cancer patients, we measured serum levels of testosterone (T), sex hormone-binding globulin (SHBG), estrone (E(1)) and adrenal androgens; and additionally, in the breast cancer patients, cortisol and corticosteroid-binding globulin and endocrine data related to breast proliferation (assessed using the Ki-67/MIB-1 monoclonal antibody) and PR levels (determined by enzyme immunoassay) in the breast cancer tissue. In the healthy women the percentage of MIB-1(+) cells showed significant negative correlations with serum levels of total T, calculated free T (fT) and the fT/E(1) ratio; while in the breast cancer patients PR content showed significant negative correlations with fT level, the fT/E(1) ratio and the T/SHBG ratio. No other correlations were found in any of the groups. Our findings in healthy women confirm previous reports of an antiproliferative effect of androgens in breast tissue and our finding in breast cancer patients suggests that this antiproliferative effect may be mediated via downregulation of PR.

Oral Contraceptives and the Risk of Death From Breast Cancer

OBJECTIVE

To examine the relationship between the use of oral contraceptives and the risk of death from breast cancer.

METHODS

We used interview data from the Cancer and Steroid Hormone Study, linked to cancer registry data from the Surveillance, Epidemiology, and End Results Program, to examine the 15-year survival and prior use of oral contraceptives among 4,292 women aged 20 to 54 years when diagnosed with breast cancer from December 1, 1980, to December 31, 1982. Cox proportional hazard models were used to estimate the relative rate of death from breast cancer by oral contraceptive use.

RESULTS

Duration of oral contraceptive use, time since first use, age at first use, and use of specific pill formulations were not associated with survival. For time since last use, the risk of death from breast cancer decreased significantly with increasing time since last use of oral contraceptives, but a consistent gradient effect was not observed. Adjusted hazard ratios ranged from 0.86 to 1.41 and were 1.00 or less for all recency categories except during 13 to 24 months before diagnosis; none was statistically significant. Women who were currently using oral contraceptives had an adjusted hazard ratio of 0.90 (0.68, 1.19).

CONCLUSION

Overall, oral contraceptive use had neither a harmful nor a beneficial effect on breast cancer mortality. The differences between pill users and nonusers were slight, and the risk estimates were usually reduced with confidence limits that nearly always included 1.0.

Androgens and the breast

There is increasing interest in the role of androgens in the treatment of women but little is known about their long-term safety. There are also very few studies on testosterone therapy and breast cancer risk. However, some observations support the concept that androgens may counteract the stimulatory effects of estrogen and progestogen in the mammary gland. Mammographic breast density and breast cell proliferation could be regarded as surrogate markers for the risk of breast cancer. Recently the addition of testosterone to a common estrogen/progestogen regimen was found to inhibit the stimulatory effects of hormones on breast cell proliferation. The effects of testosterone alone on the postmenopausal breast remain to be investigated.

Testosterone inhibits estrogen/progestogen-induced breast cell proliferation in postmenopausal women

OBJECTIVE

During the past few years serious concern has been raised about the safety of combined estrogen/progestogen hormone therapy, in particular about its effects on the breast. Several observations suggest that androgens may counteract the proliferative effects of estrogen and progestogen in the mammary gland. Thus, we aimed to study the effects of testosterone addition on breast cell proliferation during postmenopausal estrogen/progestogen therapy.

DESIGN

We conducted a 6-month prospective, randomized, double-blind, placebo-controlled study. A total of 99 postmenopausal women were given continuous combined estradiol 2 mg/norethisterone acetate 1 mg and were equally randomly assigned to receive additional treatment with either a testosterone patch releasing 300 microg/24 hours or a placebo patch. Breast cells were collected by fine needle aspiration biopsy at baseline and after 6 months, and the main outcome measure was the percentage of proliferating breast cells positively stained by the Ki-67/MIB-1 antibody.

RESULTS

A total of 88 women, 47 receiving active treatment and 41 in the placebo group, completed the study. In the placebo group there was a more than fivefold increase (P<0.001) in total breast cell proliferation from baseline (median 1.1%) to 6 months (median 6.2%). During testosterone addition, no significant increase was recorded (1.6% vs 2.0%). The different effects of the two treatments were apparent in both epithelial and stromal cells.

CONCLUSIONS

Addition of testosterone may counteract breast cell proliferation as induced by estrogen/progestogen therapy in postmenopausal women.

Risk factors for breast cancer characterized by the estrogen receptor alpha A908G (K303R) mutation

INTRODUCTION

Estrogen is important in the development of breast cancer, and its biological effects are mediated primarily through the two estrogen receptors alpha and beta. A point mutation in the estrogen receptor alpha gene, ESR1, referred to as A908G or K303R, was originally identified in breast hyperplasias and was reported to be hypersensitive to estrogen. We recently detected this mutation at a low frequency of 6% in invasive breast tumors of the Carolina Breast Cancer Study (CBCS).

METHODS

In this report, we evaluated risk factors for invasive breast cancer classified according to the presence or absence of the ESR1 A908G mutation in the CBCS, a population-based case-control study of breast cancer among younger and older white and African-American women in North Carolina. Of the 653 breast tumors evaluated, 37 were ESR1 A908G mutation-positive and 616 were mutation-negative.

RESULTS

ESR1 A908G mutation-positive breast cancer was significantly associated with a first-degree family history of breast cancer (odds ratio [OR] = 2.69, 95% confidence interval [CI] = 1.15 to 6.28), whereas mutation-negative breast cancer was not. Comparison of the two case subgroups supported this finding (OR = 2.65, 95% CI = 1.15 to 6.09). There was also the suggestion that longer duration of oral contraceptive (OC) use (OR = 3.73, 95% CI = 1.16 to 12.03; Ptrend = 0.02 for use of more than 10 years) and recent use of OCs (OR = 3.63, 95% CI = 0.80 to 16.45; Ptrend = 0.10 for use within 10 years) were associated with ESR1 A908G mutation-positive breast cancer; however, ORs for comparison of the two case subgroups were not statistically significant. Hormone replacement therapy use was inversely correlated with mutation-negative breast cancer, but the effect on mutation-positive cancer was unclear due to the small number of postmenopausal cases whose tumors carried the mutation. Mutation-negative breast cancer was associated with several reproductive factors, including younger age at menarche (OR = 1.46, 95% CI = 1.09 to 1.94) and greater total estimated years of ovarian function (OR = 1.82, 95% CI = 1.21 to 2.74).

CONCLUSION

These preliminary results suggest that OCs may interact with the ESR1 A908G mutant receptor to drive the development of some breast tumors.

Mammary carcinogenesis is preceded by altered epithelial cell turnover in transforming growth factor-alpha and c-myc transgenic mice

Identification of biomarkers that indicate an increased risk of breast cancer or that can be used as surrogates for evaluating treatment efficacy is paramount to successful disease prevention and intervention. An ideal biomarker would be identifiable before lesion development. To test the hypothesis that changes in cell turnover precede mammary carcinogenesis, we evaluated epithelial cell proliferation and apoptosis in mammary glands from transgenic mice engineered to develop mammary cancer due to expression in mammary epithelia of transforming growth factor alpha (TGF-alpha) or c-myc. In transgenic glands, before lesion development, epithelial cell turnover was enhanced overall compared with nontransgenic glands, indicating that aberrant cell turnover in normal epithelia may contribute to tumorigenesis. In addition, in tumor-containing glands, proliferation in normal epithelia was higher than in tumor-free transgenic glands, suggesting these cell populations influence one another. Finally, although c-myc glands displayed a uniformly high epithelial cell turnover regardless of age, cell turnover was reduced with aging in nontransgenic and TGF-alpha mice, indicating that some growth and death regulatory mechanisms remain intact in TGF-alpha epithelia. These observations support the evaluation of cell turnover as a biomarker of cancer risk and indicator of prevention/treatment efficacy in preclinical models and warrant validation in human breast cancer.

Are estrogen receptor content in breast cancer and effects of tamoxifen on sex hormone-binding globulin markers for individual estrogen sensitivity?

Individual women differ with respect to their sensitivity to estrogen and serum levels of sex hormone-binding globulin (SHBG) may reflect the individual response. We found a significant correlation between estrogen receptor (ER) concentrations in breast cancer tissue and SHBG levels during tamoxifen treatment. Estrogen sensitivity may be a general characteristic common to various organs and different between individual women.

Digitized assessment of mammographic breast density in patients who received low-dose intrauterine levonorgestrel in continuous combination with oral estradiol valerate: a pilot study

OBJECTIVE

To perform a pilot study of the effects on the breast by low-dose intrauterine progestogen combined with estrogen.

DESIGN

A prospective pilot study.

SETTING

University hospital.

PATIENT(S)

Twenty postmenopausal women without any previous breast disorder.

INTERVENTION(S)

Women were treated with a low-dose intrauterine system releasing 20 microg/24 hours of levonorgestrel in continuous combination with 2 mg of oral E2 valerate. The effects on mammographic breast density, breast cell proliferation, and hormonal levels were followed for 18 months.

MAIN OUTCOME MEASURE(S)

Change in mammographic breast density and breast cell proliferation. Correlations with levels of hormones, growth factors, and binding proteins.

RESULT(S)

Three women showed an apparent increase in density. For the remaining 17 women the changes were only a few percent. Digitized assessment of density showed strong correlations with visual classification scales (rs = 0.96-0.97). There was no increase in proliferation as expressed by the percentage of MIB-1-positive breast cells in fine-needle aspiration biopsies. Increase in breast density displayed a positive correlation with patients age (rs = 0.52) and an inverse relationship with levels of E2 (rs = -0.50) and free T (rs = -0.50).

CONCLUSION(S)

Low-dose intrauterine administration progestogen may develop into an attractive alternative for hormonal therapy in postmenopausal women as endometrial protection may be achieved at very low systemic levels.

Endocrine biomarkers in ductal lavage samples from women at high risk for breast cancer

BACKGROUND

Ductal lavage is a method of minimal epithelial sampling of the breast, with potential utility for repeat sampling and biomarker analysis in chemoprevention studies. We report here the baseline findings from a study designed to assess the utility of ductal lavage in this setting.

METHODS

Tamoxifen-eligible, high-risk women underwent ductal lavage; epithelial cell number (ECN) and morphology were assessed on Papanicolaou-stained slides. Additional slides were immunostained for estrogen receptor (ER) alpha, Ki-67, and cyclooxygenase-2, and the labeling index (LI) was established by counting negative and positive cells. The ductal lavage supernatant (DLS) was assayed for estradiol, several of its precursors, progesterone, cathepsin D, interleukin-6, and epidermal growth factor (EGF).

RESULTS

One hundred sixty-eight women have entered the study (mean age, 51 years; mean 5-year Gail score, 2.8). Ductal lavage was accomplished in 145 (86.3%) women. Data were analyzed by duct and by woman (averaging data across all ducts). Mild atypia was seen in 43 of 145 (29.6%), whereas severe atypia was seen in 2 (1.4%) of women. We observed significant positive correlations between ECN and cytologic atypia, ER LI, cyclooxygenase-2 LI, and Ki-67 LI. EGF levels in supernatant were significantly associated with estrogenic precursors, ER LI and ECN. A factor representing the DLS hormone and protein variables explained 36% of the variance; total ECN was highest when factor score and ER LI were high and was lowest when both were low (P for interaction = 0.001).

CONCLUSIONS

Biomarker analyses in epithelial cells and DLS are feasible. The significant associations of EGF with other markers suggest a possible role in increasing epithelial cell mass.

Steroid receptor expression in vaginal epithelium of healthy fertile women and influences of hormonal contraceptive usage

BACKGROUND

The objective of this study was to evaluate whether long-term usage of hormonal contraceptives modifies the steroid receptor expression in the human vaginal epithelium of healthy young women.

METHODS

In a cross-sectional study, three groups of hormonal contraceptive users [combined oral contraceptives (COCs), levonorgestrel implants (LNG) and depot medroxyprogesterone acetate injections (DMPAs)] were compared to controls. Fifteen subjects (20-34 years) were enrolled to each group. Vaginal biopsies were collected at two occasions from each subject, and serum concentrations of E(2) and progesterone were measured. Monoclonal antibodies directed against progesterone receptors (PRs) and estrogen receptors (ERs) were used in immunohistochemistry on formalin-fixed tissue sections of vaginal mucosa. A program for immunohistomorphometric quantification was devised to estimate frequency of epithelial steroid receptor-expressing cells.

RESULTS

Progesterone receptor expression was markedly down-regulated and significantly reduced in DMPA users compared to controls, COC and LNG users. In DMPA users, the ER expression was significantly elevated in the first compared to the second sample, and significantly elevated compared to LNG users. Estradiol concentration in serum was significantly reduced in hormonal contraceptive users compared to controls.

CONCLUSIONS

Steroid receptor expression in human vaginal epithelium is altered by long-term use of DMPA compared to controls.

Breast cancer: new technologies for risk assessment and diagnosis

In the US, one in every eight women will develop breast cancer in her lifetime. Despite the advances made in treating breast cancer, the causal mechanisms underlying this disease have yet to be fully elucidated; 85% of breast cancer cases occur sporadically without any known genetic mutation. Too little is known about the pathogenesis of breast cancer for primary prevention to be feasible in the near- to mid-term. Secondary prevention through screening offers an alternative that has been widely adopted. For decades, breast self-examination has been touted as a technique for the early identification of breast cancer. However, it has been recently suggested that this technique is a waste of time and resources for both doctors and patients. Mammography finds breast cancer earlier than breast self-examination, and will reduce the risk of death from breast cancer by approximately 30% in women over 50 years old. Mammography is limited in that cancer, like breast tissue, appears white on the x-ray; therefore lesions may be difficult to detect in women with very dense breasts, and a tumor may not cast a significant shadow until it is quite large. Some cancers are so aggressive that they can spread quickly, before routine screening can detect them. Despite these limitations, mammography is still viewed as the best tool currently available for screening and early diagnosis. Improved methods to detect and diagnose breast cancer early, when it is most curable, are required if a significant impact on morbidity and mortality from breast cancer is to be made. Various new and innovative technologies are being investigated for improving the early detection and diagnosis of breast cancer. About 85% of breast cancers begin in the milk ductal system of the breast. As cancer develops in the breast, abnormalities occur, including atypical hyperplasia, ductal carcinoma in situ, and invasive breast carcinoma. Thus, the early screening of ductal cells can provide a parallel benefit to the 'Pap' smear, which is used virtually universally to identify the abnormal cells that can lead to cervical cancer. Two technologies to monitor for atypical ductal epithelial cells are Cytyc Corporation's FirstCyte Ductal Lavage system and Nastech Pharmaceutical Company's Mammary Aspiration Cytology Test. Matritech, Inc. is searching for biomarkers linked to breast cancer. Researchers at Matritech have detected the presence of nuclear matrix protein (NMP) in the blood of women at the early stage of breast cancer, which is absent in the blood of healthy women, as well as those with fibroadenoma, a benign breast disease. NMP66 has been selected as a marker for further development and clinical trials of a test for use in the detection and monitoring of women with, or at risk for, breast cancer have been initiated. Technologies developed by the US Department of Defense are under investigation as breast cancer screening. Advanced Image Enhancement, Inc. has licensed naval sonar technology for digital image enhancement of mammograms. New thermography applications are also being investigated in two separate projects sponsored by the US Department of Defense using military thermal surveillance tools adapted for cancer detection. Both are enhancements of older thermal imaging technology based on the principle that heat equates to unwanted activity, in the case of breast cancer, abnormal cell proliferation.

Oral contraceptive use and risk of early-onset breast cancer in carriers and noncarriers of BRCA1 and BRCA2 mutations

BACKGROUND

Recent oral contraceptive use has been associated with a small increase in breast cancer risk and a substantial decrease in ovarian cancer risk. The effects on risks for women with germ line mutations in BRCA1 or BRCA2 are unclear.

METHODS

Subjects were population-based samples of Caucasian women that comprised 1,156 incident cases of invasive breast cancer diagnosed before age 40 (including 47 BRCA1 and 36 BRCA2 mutation carriers) and 815 controls from the San Francisco Bay area, California, Ontario, Canada, and Melbourne and Sydney, Australia. Relative risks by carrier status were estimated using unconditional logistic regression, comparing oral contraceptive use in case groups defined by mutation status with that in controls.

RESULTS

After adjustment for potential confounders, oral contraceptive use for at least 12 months was associated with decreased breast cancer risk for BRCA1 mutation carriers [odds ratio (OR), 0.22; 95% confidence interval (CI), 0.10-0.49; P < 0.001], but not for BRCA2 mutation carriers (OR, 1.02; 95% CI, 0.34-3.09) or noncarriers (OR, 0.93; 95% CI, 0.69-1.24). First use during or before 1975 was associated with increased risk for noncarriers (OR, 1.52 per year of use before 1976; 95% CI, 1.22-1.91; P < 0.001).

CONCLUSIONS

There was no evidence that use of current low-dose oral contraceptive formulations increases risk of early-onset breast cancer for mutation carriers, and there may be a reduced risk for BRCA1 mutation carriers. Because current formulations of oral contraceptives may reduce, or at least not exacerbate, ovarian cancer risk for mutation carriers, they should not be contraindicated for a woman with a germ line mutation in BRCA1 or BRCA2.

Estradiol and medroxyprogesterone acetate regulated genes in T47D breast cancer cells

Many mammary tumors express estrogen receptors (ER) and progesterone receptors (PR), and there is increasing evidence that progestins influence gene expression of breast tumor cells. To analyse the impact of progestins on breast cancer cells, we compared (a) the expression of two cytokines, involved in tumor progression, and searched (b) for differentially regulated genes by a microarray, containing 2400 genes, on T47D breast cancer cells cultured for 6 days with 17beta-estradiol (E2) or E2+medroxyprogesterone acetate (E2+MPA). Lower amounts of PDGF and TNFalpha were found in culture supernatants of E2+MPA treated T47D cells. MPA addition induced a 2.8-3.5-fold increase of the mRNA expression of (a) tristetraprolin, which is involved in the posttranscriptional regulation of cytokine biosynthesis, and (b) zinc-alpha2-glycoprotein and Na, K-ATPase alpha1-subunit, which both resemble differentiation markers of breast epithelium. In contrast, the mRNA expression of lipocalin 2, which promotes matrixmetalloproteinase-9 activity, was decreased five-fold in E2+MPA treated cells. Our data show that the expression of genes from various functional gene families is regulated differentially by E2 and E2+MPA treatment in T47D cells. This suggests that exogenous progestins applied for therapy and endogenous changes of the progesterone levels during the menstrual cycle both influence breast cancer pathophysiology.

Lack of synergy between estrogen and progesterone on local IGF-I, IGFBP-3 and IGFBP-2 secretion by both hormone-dependent and hormone-independent breast cancer explants in vitro. Effect of tamoxifen and mifepristone (RU 486)

The aim of the present study was to investigate direct effects of estrogen (E2) or progesterone (P4) given separately vs. estrogen+progesterone on local IGF-I, IGFBP-3 and IGFBP-2 secretion. Explants obtained from estrogen receptor positive plus progesterone receptor positive (ER+/PR+) and hormone receptors negative (ER-/PR-) tumors were incubated with E2, P4 or both. Tamoxifen was added to E2-exposed cultures; mifepristone (RU 486) was added to P4, and both were given to E2+P4-supplemented cultures. In hormone-dependent and hormone-independent tissues, treatment with estrogen+progesterone increased IGF-I and IGFBP-2 secretion with concomitant decrease in IGFBP-3, in the same manner as E2 or P4 given alone. Tamoxifen decreased the E2- and E2+P4-stimulated IGF-I secretion by hormone-dependent breast cancer explants. RU 486 decreased the P4- and E2+P4-stimulated IGF-I secretion with parallel stimulation of IGFBP-3 secretion by ER+/PR+ explants. Estradiol and progesterone had a synergistic action on IGFBP-2 secretion by hormone-dependent breast cancer explants. In conclusion, the presented data suggest that there is no synergistic action of E2 and P4 in influencing IGF/IGFBPs ratio and, additionally, suggest a protective action of antiestrogen and antiprogestagen against excessive IGF-I secretion.

Different effects of tibolone and continuous combined estrogen plus progestogen hormone therapy on sex hormone binding globulin and free testosterone levels--an association with mammographic density

OBJECTIVE

To compare the effects of tibolone and continuous combined hormone therapy on circulating sex steroids and their binding proteins and their relationship to mammographic density.

STUDY DESIGN

A prospective, double-blind placebo-controlled study. A total of 166 postmenopausal women were equally randomized to receive tibolone 2.5 mg, estradiol 2 mg/norethisterone acetate 1 mg (E2/NETA) or placebo. Serum analyses of sex steroids, insulin-like growth factor (IGF-I) and binding proteins and assessment of mammographic breast density were performed at baseline and after 6 months of treatment.

RESULTS

Estrogens were markedly increased and androgens decreased by E2/NETA. In contrast, tibolone had only a minor influence on circulating estrogens. Sex hormone binding globulin (SHBG) levels were reduced by 50%, while levels of androgens increased. Baseline values of estrone sulfate (E1S), around 1.0-1.1 nmol/l, were increased to 44.7 nmol/l by E2/NETA and to only 1.7 nmol/l by tibolone (p < 0.001). Mammographic breast density displayed a negative correlation with age and body mass index and a positive association with SHBG. After 6 months there was also a negative correlation with levels of free testosterone. Conclusion We found that tibolone and E2/NETA caused distinct differences in estrogen/androgen status and blood levels of possible breast mitogens. The negative association between free testosterone and mammographic density could be a possible explanation for tibolone having less influence on the breast.

Cyclic changes in the mammary gland of cynomolgus macaques

OBJECTIVE

To evaluate the influence of hormonal changes during the menstrual cycle on the mammary gland of female cynomolgus monkeys.

DESIGN

Paired breast biopsy samples were obtained during the follicular and luteal phases of the cycle. Cycle characteristics were assessed by vaginal bleeding, serum hormones, vaginal cytology, and uterine ultrasound. The mammary gland was assessed by histology and immunohistochemistry for Ki67, estrogen receptors (ER) alpha and beta, progesterone receptors (PR), and cleaved caspase 3 (CPP32).

SETTING

Nonhuman primate study in an academic research environment.

ANIMAL(S)

Fifty-two adult, female, feral cynomolgus macaques (Macaca fascicularis), aged 8 to 20 years, obtained from the breeding colony of the Institut Pertanian Bogor (Bogor, Indonesia).

INTERVENTION(S)

None

MAIN OUTCOME MEASURE(S)

Breast histomorphometry, immunohistochemical detection of Ki67, ERs, PR, and CPP32 in breast epithelial cells, and correlation with serum estradiol and progesterone.

RESULT(S)

Serum hormones, vaginal cytology and bleeding patterns were indicative of cycle stage. For lobules, Ki67 expression was higher in the follicular than in the luteal phase. In ducts, Ki67 expression was higher in the luteal than in the follicular phase. Estrogen receptors did not change across the cycle, but ER beta was more abundant. Ductal PR decreased in the luteal phase. Lobular CPP32 was higher during the luteal phase. Correlations of serum estradiol to outcomes varied by cycle stage.

CONCLUSION(S)

These data indicate important regulatory differences in the balance of proliferation and apoptosis in epithelial subpopulations within the breast across the menstrual cycle, indicating different regulatory roles for ER alpha and beta.

A comparative study of breast cell proliferation during hormone replacement therapy: effects of tibolon and continuous combined estrogen-progestogen treatment

OBJECTIVE

To use the fine-needle aspiration (FNA) biopsy technique to compare the effects of tibolone, conventional hormone replacement therapy (HRT) and placebo on breast cell proliferation in postmenopausal women.

METHODS

A total of 91 women were randomized to receive either estradiol 2 mg plus norethisterone acetate 1 mg (E2/NETA), tibolone 2.5 mg or placebo for 6 months in a prospective double-blind trial. Breast cell proliferation was assessed using the Ki-67/MIB-1 monoclonal antibody.

RESULTS

From the 83 women who completed the study, a total of 166 FNA biopsies were obtained, and 118 of these aspirates (71%) were evaluable for MIB-1 content. Women with assessable biopsies were younger, had a lower body mass index, and had higher levels of sex hormone binding globulin and insulin-like growth factor-I than women in whom the cell yield was insufficient. During treatment with E2/NETA, there was an increase in proliferation (percentage of MIB-1) from a mean value of 2.2 to 6.4% after 6 months (p < 0.01). No significant changes were recorded during treatment with tibolone or placebo. There was a negative association between proliferation and serum levels of total (r(s) = -0.29, p < 0.05) and free (rs = -0.31, p < 0.03) testosterone.

CONCLUSIONS

Tibolone seems to have little influence on breast cell proliferation.

Lessons to be learned from clinical studies on hormones and the breast

Estrogen is a well-known mitogen in human breast epithelium but the action of progestogen is complex and incompletely understood. During the last years, accumulating data from animal, clinical and observational studies suggest a proliferative effect in breast tissue when progestogen is added to estrogen. Findings in surrogate markers like breast density add to clinical and epidemiological reports indicating that continuous combined HRT may carry a higher risk of breast cancer than treatment with estrogen alone. Whether the results are valid for all progestogens remains to elucidated. It is also clear that not all women respond in the same way to the same treatment and the biological basis for the marked individual variation in breast response has to be clarified. Further knowledge about the role of androgens and of the impact of different treatment regimens is important and prospective randomized clinical studies are needed.