Estrogen and combined estrogen–progestogen therapy in the menopause and breast cancer

Formononetin and metformin act synergistically to inhibit growth of MCF-7 breast cancer cells in vitro

Many breast cancer patients suffer from obvious side effects induced by chemotherapy. Formononetin (FM), one kind ingredient of Chinese herbal medicine, has been suggested to inhibit MCF-7 breast cancer cells. And recently metformin (MET) has gained more attention as a potential anti-cancer drug. The aim of this study was to investigate the synergistic effects of FM and MET on the proliferation of MCF-7 cells and to clarify the possible molecular mechanism involved. MCF-7 cells were treated with various concentrations of FM (40 and 80 μM) or FM (40 and 80 μM) combined with MET (150 μM) for 48 h. Cell proliferation was tested by an methyl tetrazolium (MTT) (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) assay. The percentage of apoptotic cells was measured by flow cytometry. The expression level of b-cell lymphoma/leukemia-2 (bcl-2) mRNA was examined by RT-PCR, while the expression levels of phosphorylated extracellular signal-regulated kinases (p-ERK1/2) and bcl-2 protein were detected by Western blotting. Compared with untreated cells, 40 μM and 80 μM FM efficiently inhibited proliferation and increased apoptosis in MCF-7 cells. Additionally, 40 μM and 80 μM FM greatly downregulated bcl-2 mRNA expression when compared with untreated cells. Furthermore, the protein expression of bcl-2 and p-ERK1/2 was significantly reduced by 40 μM and 80 μM FM. The cytotoxic effect of FM was more remarkable when 150 μM MET was added. Taken together, the combinational use of FM and MET enhanced cell growth inhibition, and the induction of apoptosis in MCF-7 cells mediated by the ERK1/2 signaling pathway.

Breast Cancer Risk Associated with Estrogen Exposure and Truncating Mutation Location in BRCA1/2 Carriers

BACKGROUND

Mutations in BRCA1/2 confer a high risk of breast cancer, but literature values of this risk vary. A genotype-phenotype correlation has been found in both genes, and the effect of reproductive factors differs according to mutation location. Therefore, we hypothesize that such a variation may exist for other factors related to estrogen exposure.

METHODS

We used a weighted Cox regression model to assess variation in breast cancer risk with these factors using location of mutation in homogeneous breast cancer risk region of BRCA1/2 in the GENEPSO study.

RESULTS

We found that late age at menarche reduced breast cancer risk by 31% and that among BRCA1 carriers, a long or a short menstrual cycle increased risk (by 65% and 73%, respectively). Among premenopausal women, overweight was associated with a 45% decrease in risk whereas underweight was associated with an increased risk (HR, 2.40). A natural menopause, mainly after age 50, was associated with a high breast cancer risk (HR, 2.46), and a significant interaction between menopause status and the location of mutations was found leading up to 10% variation in absolute risk according to the age at menopause.

CONCLUSIONS

As observed in the general population, a late menarche, a long or a short menstrual cycle, over- or underweight, and being postmenopausal were associated with breast cancer risk in BRCA1/2 carriers. The association with the menopause was observed only when the mutation was located in the "high-risk" zones.

IMPACT

Taking into account modifier factors, location of mutation might be important for the clinical management of BRCA1/2 mutation carriers.

Hormone replacement therapy and some risk factors for breast cancer among Slovenian postmenopausal women

OBJECTIVE

The aim of the study was to examine the influence of the use of hormone replacement therapy (HRT) and of some generally recognized risk factors on breast cancer risk among Slovenian postmenopausal women.

METHODS

Eligible women diagnosed with breast cancer and a control group of women of the same age and ethnicity were invited to participate in the case-control study via a personal letter and asked to complete a written questionnaire. Adjusted odds ratios and 95% confidence intervals were estimated using multivariate logistic regression analysis.

RESULTS

A total of 784 cases and 709 controls aged 50-69 years were enrolled. HRT use was inversely associated with breast cancer risk. The effect was most pronounced with the use of estrogen-only replacement therapy (odds ratio (OR) 0.51, 95% confidence interval (CI) 0.30-0.87). Longer duration of HRT use did not result in a significant change in risk (1 to <5 years of HRT use: OR 0.44, 95% CI 0.26-0.73; ≥ 5 years of HRT use: OR 0.51, 95% CI 0.30-0.87). Obesity (25 ≤ body mass index <30 kg/m(2): OR 1.34, 95% CI 1.04-1.73; body mass index ≥ 30 kg/m(2): OR 1.89, 95% CI 1.36-2.63), smoking ≥ 10 cigarettes per day (OR 1.70, 95% CI 1.20-2.43), and any first-degree relative with breast or ovarian cancer (OR 1.52, 95% CI 1.11-2.08) were positively associated with breast cancer risk.

CONCLUSIONS

Our analysis revealed some differences from the previously published literature, which might reflect underlying demographic changes. Comprehensive medical care in HRT users without pre-existing breast abnormalities probably reduces the incidence of new breast cancer cases in Slovenia.

Women live longer than men: understanding molecular mechanisms offers opportunities to intervene by using estrogenic compounds

Women live longer than men. Moreover, females live longer than males in some, but not all, experimental animals. The differences in longevity between genders are related to free radical production. Indeed, females produce less radicals only in animal species in which they live longer than males. This is because estrogens upregulate antioxidant longevity-related genes. These considerations have led us to postulate an extended concept of antioxidant in biology: an antioxidant is any nutritional, physiological, or pharmacological manipulation that increases the expression and activity of antioxidant genes or proteins. Phytoestrogens or other selective estrogen receptor modulators lower age-related diseases and prolong life span, at least in experimental animals. This provides rational bases to study their action in humans further.

Current breast cancer risks of hormone replacement therapy in postmenopausal women

The controversies surrounding hormone replacement therapy have left many women confused and afraid. Providers have been faced with long-standing assumptions challenged by an abundance of new data in the past few years, with little guidance on how to interpret these findings. The objective of this paper is to provide a framework for understanding breast cancer risk associated with postmenopausal hormone replacement therapy, with a particular focus on how observational studies and randomised trials provide complementary information. This framework considers the data on risks of various hormonal preparations, the profiles of women at risk, and ends with an expert opinion in this context.

Estrogen–progestogen replacement therapy and ovarian cancer: an update

Hormone replacement therapy in menopause has been associated with a moderate increase in ovarian cancer risk. Data on combined estrogen-progestin therapy, based on one randomized trial, two cohort and four case-control studies, do not provide definite evidence of an association between combined hormone replacement therapy and ovarian cancer. These data do not suggest, however, substantial differences between the effect of estrogen only or unspecified hormone replacement therapy and combined hormone replacement therapy on ovarian cancer risk.

The effect of lifestyle factors on gynaecological cancer

Several lifestyle factors affect a woman's risk of gynaecological cancer and-potentially-can be modified to reduce risk. This chapter summarises the evidence for the effect of lifestyle factors on the incidence of gynaecological malignancy. The incidence of obesity is increasing in the developed world such that it now contributes as much as smoking to overall cancer deaths. Women with a body mass index (BMI)>40 have a 60% higher risk of dying from all cancers than women of normal weight. They are also at increased risk from gynaecological cancer. Dietary factors significantly influence the risk of gynaecological cancer: fruit, vegetables and antioxidants reduce risk whereas high animal fat and energy intakes increase risk. Alcohol intake adversely affects breast cancer risk, possibly accounting for 4% of all breast cancers. Physical activity protects against ovarian, endometrial and postmenopausal breast cancer, independently of BMI. The oral contraceptive pill has a substantial and long-lasting effect on the prevention of ovarian and endometrial cancer and is one of the best examples of large-scale chemoprevention in the developed world. Childbearing is protective against ovarian, endometrial and breast cancer but increases the risk of cervical cancer. Smoking acts as a cofactor in cervical carcinogenesis and increases the risk of ovarian cancer, particularly mucinous tumours.

Where are we with postmenopausal hormone therapy in 2005?

Recently, two large randomized placebo-controlled studies on long-term postmenopausal hormone replacement therapy, the Heart and Estrogen/progestin Replacement Study (HERS) and the Women's Health Initiative (WHI), have raise a lot of controversies, especially on the cardiovascular aspects. We briefly review these two trials and discuss what we know and do not know about postmenopausal hormone therapy, including the evidence on novel choices such as raloxifene and tibolone.

Breast cancer risk with postmenopausal hormonal treatment

This review was designed to determine from the best evidence whether there is an association between postmenopausal hormonal treatment and breast cancer risk. Also, if there is an association, does it vary according to duration and cessation of use, type of regimen, type of hormonal product or route of administration; whether there is a differential effect on risk of lobular and ductal cancer; and whether hormone treatment is associated with breast cancers that have better prognostic factors? Data sources for the review included Medline, the Cochrane Database of Systematic Reviews (Cochrane Library, 2005) and reference lists in the identified citations. Eligible citations addressed invasive breast cancer risk among postmenopausal women and involved use of the estrogen products with or without progestin that are used as treatment for menopausal symptoms. Abstracted data were demographic groupings, categories of hormone use, categories of breast cancer, two-by-two tables of exposure and outcome and adjusted odds ratios, relative risks (RRs) or hazard rates. Average estimates of risk were weighted by the inverse variance method, or if heterogeneous, using a random effects model. The average risk of invasive breast cancer with estrogen use was 0.79 [95% confidence interval (95% CI) = 0.61-1.02] in four randomized trials involving 12 643 women. The average breast cancer risk with estrogen-progestin use was 1.24 (95% CI = 1.03-1.50) in four randomized trials involving 19 756 women. The average risks reported in recent epidemiological studies were higher: 1.18 (95% CI = 1.01-1.38) with current use of estrogen alone and 1.70 (95% CI = 1.36-2.17) with current use of estrogen-progestin. The association of breast cancer with current use was stronger than the association with ever use, which includes past use. For past use, the increased breast cancer risk diminished soon after discontinuing hormones and normalized within 5 years. Reasonably adequate data do not show that breast cancer risk varies significantly with different types of estrogen or progestin preparations, lower dosages or different routes of administration, although there is a small difference between sequential and continuous progestin regimens. Epidemiological studies indicate that estrogen-progestin use increases risk of lobular more than ductal breast cancer, but the number of studies and cases of lobular cancer remains limited. Among important prognostic factors, the stage and grade in breast cancers associated with hormone use [corrected] do not differ significantly from those in non-users, but breast cancers in estrogen-progestin users are significantly more likely to be estrogen receptor (ER) positive. In conclusion, valid evidence from randomized controlled trials (RCTs) indicates that breast cancer risk is increased with estrogen-progestin use more than with estrogen alone. Epidemiological evidence involving more than 1.5 million women agrees broadly with the trial findings. Although new studies are unlikely to alter the key findings about overall breast cancer risk, research is needed, however, to determine the role of progestin, evaluate the risk of lobular cancer and delineate effects of hormone use on receptor presence, prognosis and mortality in breast cancer.