Endocrine and paracrine hormones in the promotion, progression and recurrence of breast cancer

Androgen excess in breast cancer development: implications for prevention and treatment

The aim of this review is to highlight the pivotal role of androgen excess in the development of breast cancer. Available evidence suggests that testosterone controls breast epithelial growth through a balanced interaction between its two active metabolites: cell proliferation is promoted by estradiol while it is inhibited by dihydrotestosterone. A chronic overproduction of testosterone (e.g. ovarian stromal hyperplasia) results in an increased estrogen production and cell proliferation that are no longer counterbalanced by dihydrotestosterone. This shift in the androgen/estrogen balance partakes in the genesis of ER-positive tumors. The mammary gland is a modified apocrine gland, a fact rarely considered in breast carcinogenesis. When stimulated by androgens, apocrine cells synthesize epidermal growth factor (EGF) that triggers the ErbB family receptors. These include the EGF receptor and the human epithelial growth factor 2, both well known for stimulating cellular proliferation. As a result, an excessive production of androgens is capable of directly stimulating growth in apocrine and apocrine-like tumors, a subset of ER-negative/AR-positive tumors. The key role of androgen excess in the genesis of different subtypes of breast cancer has significant clinical implications for both treatment and prevention. Our belief stems from a thorough analysis of the literature, where an abundance of evidence is present to justify a clinical trial that would investigate the effectiveness of treating the underlying excessive androgen production.

Factors of Risk for Breast Cancer Influencing Post-Menopausal Long-Term Hormone Replacement Therapy

The advantages of hormone replacement therapy (HRT) are well documented in contrasting the symptomatology of climacterium and in reducing morbidity and mortality associated with coronary heart disease and osteoporotic fractures of postmenopausal age. However, growing evidence points to increased breast cancer risk in HRT long-term users, and the adverse effect would, obviously, overwhelm any other benefit. At present, the risk/benefit ratio of HRT is an object of hot debate, and we feel it necessary and urgent to select women who can safely benefit from HRT and women whose risk of breast cancer can be perilously increased by the raised hormonal levels related to HRT. We have reviewed studies on the breast cancer risk in HRT users and data on the interaction between steroid hormones and breast cancer. Reasoning that the outcome of mammary cancer can be increased by hormonal overstimulation of the breast, we have focused on those factors of risk that could be further enhanced by the exogenous hormonal stimulus of HRT, so as to cause a further significant increase in the risk of breast cancer. We conclude that some biologic and clinical markers, namely android obesity, bone density, mammographic density, androgen and estrogen circulating levels, alcohol consumption, benign breast disease, and familiarity, should be carefully considered before prescribing long-term HRT. Our analysis suggests that HRT could increase the risk of breast cancer and useless in preventing coronary heart disease and osteoporotic fractures when administered in women with positivity for one or more of these markers.

Genetic Determinants of Nipple Aspiration Fluid Yield

PURPOSE

Nipple aspiration fluid (NAF) is a non-invasively-acquired biosample that can provide a window into the breast environment, but NAF yield is highly variable. Its determinants must be better understood for studies of breast cancer risk. The wet earwax phenotype was identified as one determinant of NAF yield in the 1970s, and is linked to single nucleotide polymorphisms (SNPs) in the ATP-binding cassette transporter gene ABCC11. We have investigated this, as well as SNPs in the prolactin (PRL) and prolactin receptor (PRLR) genes, in relation to NAF yield.

METHODS

DNA was extracted from white blood cells of 557 NAF yielders and 359 non-yielders, and was used to genotype ABCC11 (rs17822931), PRL (rs849870, rs849872, rs849886, rs2244502, rs1341239), and PRLR (rs37364, rs34024951, rs1610218, rs9292575, rs7718468) using Taqman genotyping assay. The association between NAF yield and each single SNP was analyzed using logistic regression adjusting for age, race, and menopausal status.

RESULTS

ABCC11 rs17822931 showed a negative association with NAF yield [odds ratio (OR) 0.66, 95 % confidence interval (CI) 0.49-0.88; p = 0.004]. The PRL rs849870 and the haplotype combination with other SNPs showed a marginal association with NAF yield. In addition, the years since last birth also showed negative association with NAF yielding (OR 0.98, 95 % CI 0.96-0.99; p = 0.001). The combination of the years since last birth with ABCC11 SNP revealed significant interaction between reproductive factor and genetic factor.

CONCLUSIONS

Our results confirmed the association between NAF yield and earwax phenotype through ABCC11 genotype. Combined with the recency of last birth, ABCC11 genotype should be considered in the design of studies utilizing NAF as a biosample.

Progesterone--promoter or inhibitor of breast cancer

Based on the results of a French cohort of postmenopausal women, it has been claimed that micronized progesterone does not enhance breast cancer risk. The impact of reproductive factors on breast cancer risk and a high prevalence of occult breast carcinomas at the time of menopause suggest an involvement of endogenous progesterone in the development of breast cancer. High mammographic density in the luteal phase and during treatment with estrogen/progestogen combinations reflect a change in the composition of mammary stroma and an increased water accumulation in the extracellular matrix which is caused by hygroscopic hyaluronan-proteoglycan aggregates. Proteoglycans are also involved in the regulation of proliferation, migration, and differentiation of epithelial cells and angiogenesis, and may influence malignant transformation of breast cells and progression of tumors. Reports on a lack of effect of estrogen/progesterone therapy on breast cancer risk may be rooted in a selective prescription to overweight women and/or to the very low progesterone serum levels after oral administration owing to a strong inactivation rate. The contradictory results concerning the proliferative effect of progesterone may be associated with a different local metabolism in normal compared to malignant breast tissue. Similar to other progestogens, hormone replacement therapy with progesterone seems to promote the development of breast cancer, provided that the progesterone serum levels have reached the threshold for endometrial protection.

Dietary chalcones with chemopreventive and chemotherapeutic potential

Chalcones are absorbed in the daily diet and appear to be promising cancer chemopreventive agents. Chalcones represent an important group of the polyphenolic family, which includes a large number of naturally occurring molecules. This family possesses an interesting spectrum of biological activities, including antioxidative, antibacterial, anti-inflammatory, anticancer, cytotoxic, and immunosuppressive potential. Compounds of this family have been shown to interfere with each step of carcinogenesis, including initiation, promotion and progression. Moreover, numerous compounds from the family of dietary chalcones appear to show activity against cancer cells, suggesting that these molecules or their derivatives may be considered as potential anticancer drugs. This review will focus primarily on prominent members of the chalcone family with an 1,3-diphenyl-2-propenon core structure. Specifically, the inhibitory effects of these compounds on the different steps of carcinogenesis that reveal interesting chemopreventive and chemotherapeutic potential will be discussed.

The expression of syndecan-1, syndecan-4 and decorin in healthy human breast tissue during the menstrual cycle

BACKGROUND

In order to unravel the interactions between the epithelium and the extra cellular matrix (ECM) in breast tissue progressing to cancer, it is necessary to understand the relevant interactions in healthy tissue under normal physiologic settings. Proteoglycans in the ECM play an important role in the signaling between the different tissue compartments. The proteoglycan decorin is abundant in the breast stroma. Decreased expression in breast cancer tissue is a sign of a poor tumor prognosis. The heparane sulphate proteoglycans syndecan-1 and syndecan-4 promote the integration of cellular adhesion and proliferation. The aim of this study was to investigate the gene expression and location of decorin, syndecan-1 and syndecan-4 in the healthy breast during the menstrual cycle.

METHODS

Tissue from healthy women undergoing breast reduction plastic surgery was examined using immunohistochemistry (n = 38) and Real-Time RT-PCR (n = 20). Both parous and nulliparous women were eligible and the mean age of the women was 34(+/- 10 years) with regular menstrual cycles (28 +/- 7 days). None of the women had used hormonal treatment the last three months. The women were randomized to needle biopsy two months before the operation in the follicular or luteal menstrual phase and for another biopsy at the operation in the opposite phase. Serum samples were obtained to characterize the menstrual phase. The Wilcoxon signed rank test and Mann Whitney test were used for statistical analyses.

RESULTS

By real time-RT-PCR the gene signal for all three proteoglycans; decorin (p = 0.02) and syndecan-1 (p = 0.03) and syndecan-4 (p = 0.02) was significantly lower among parous women in the luteal phase than in the follicular phase. Immunohistochemistry confirmed the identification of the proteins but no significant difference between menstrual phases was observed. Serum samples verified the menstrual phase.

CONCLUSIONS

Our study shows, for the first time in the healthy breast, a significantly lower expression of the genes for the three proteoglycans, decorin, syndecan-1 and syndecan-4 in the luteal phase during the menstrual cycle. These changes were registered under normal physiologic conditions. Since ECM molecules appear to be involved in tumor progression, these findings in the normal breast could constitute a base for further studies in women receiving hormonal therapy or those with breast cancer.

Prevention of oxidative DNA damage by bioactive berry components

The hormone 17ss-estradiol (E(2)) causes oxidative DNA damage via redox cycling of its metabolites such as 4-hydroxy estradiol (4E(2)). In this study, ACI rats (8 wk old) were fed either AIN-93M diet or diets supplemented with 0.5% each of mixed berries (strawberry, blueberry, blackberry, and red and black raspberry), blueberry alone (BB; 2.5%), or ellagic acid (EA; 400 ppm) from 2 wk prior to and up to 12 wk of E(2) treatment. The liver DNA was analyzed for the presence of 8-oxo-7,8-dihydroguanine (8-oxodG) and other polar adducts by 32P-postlabeling. Compared to sham treatment, E(2) significantly increased the levels of both 8-oxodG and P-1 subgroup (259% and 214%, respectively; P< 0.05). EA diet significantly reduced E(2)-induced levels of 8-oxodG, P-1, P-2, and PL-1 by 79, 63, 44, and 67%, respectively (P< 0.001). BB diet also significantly reduced the levels of P-1, P-2, and PL-1 subgroups by 77, 43, and 68%, respectively (P< 0.001). Mixed berries were, however, ineffective. In addition, aqueous extracts of berries (2%) and EA (100 microM) were tested for their efficacy in diminishing oxidative DNA adducts induced by redox cycling of 4E(2) catalyzed by copper chloride in vitro. EA was the most efficacious (90%), followed by extracts of red raspberry (70%), blueberry, and strawberry (50% each; P< 0.001).

Effects of tibolone and conventional HRT on the expression of estrogen and progesterone receptors in the breast

OBJECTIVE

There is evidence that long-term hormone replacement therapy (HRT) is associated with an increased breast cancer risk. The aim of this study was to assess the effects of tibolone on estrogen and progesterone receptors in comparison to the effects of conventional HRT in the breast of surgically postmenopausal macaques.

METHOD

Sixty macaques were bilaterally ovariectomized 3 months before hormonal treatment was initiated. The animals were randomized into four treatment groups, including tibolone (TIB), conjugated equine estrogens (CEE), conjugated equine estrogens+medroxyprogesterone acetate (CEE+MPA) and control animals (C). After 2 years treatment, breast tissues were collected, fixed and paraffin embedded. Immunohistochemistry assays with monoclonal antibodies for estrogen receptors (ERalpha and ERbeta) and progesterone receptors (PRA and PRB) were performed.

RESULTS

The expression of ERalpha was markedly decreased in the CEE+MPA group as compared to C and TIB groups. The TIB group was not different from the C and CEE groups. No significant differences were found for ERbeta immunostaining. The expression of PRA was strongly increased in the TIB group as compared to the C and CEE+MPA groups. Immunostaining of PRB was increased in the CEE and TIB treated animals as compared to both C and CEE+MPA groups.

CONCLUSIONS

Tibolone increased the expression of both PRA and PRB, without affecting ERalpha and ERbeta expression in the macaque breast. These findings indicate that the effects of tibolone in breast tissue could be mediated via differential regulation of PRA and PRB isoforms and therefore distinct from those observed with conventional HRT.

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.

Hormone therapy and estrogen receptor expression in breast cancer

Postmenopausal hormone therapy (HT) may increase breast cancer risk and influence tumor characteristics. We investigated 321 postmenopausal women aged 50-65 years, with breast cancer, diagnosed and treated at Radiumhemmet, Karolinska Hospital, during 1993-1997. In women using HT (n =90) estrogen receptor concentration (ER) at diagnosis were lower than in non-users (n =135) (1.17 vs 1.70 fmol/microg; p <0.05). HT users also had a tendency to less multifocal (5 vs 12%) (p <0.05) and metastatic disease (5% vs 2%) however this was not statistically significant. The estrogen receptor expression is always considered in the judgement on hormone dependency and the clinical decision on adjuvant endocrine therapy. A suppression of ER during HT could tentatively influence the treatment decisions in breast cancer patients and maybe disregard patients from endocrine treatment.

Breast response to menopausal hormone therapy--aspects on proliferation, apoptosis and mammographic density

Breast cancer is the major malignancy among women in the Western world. The breast is clearly a target organ for sex steroid hormones and hormonal treatments have been associated with an increased risk of breast cancer. The balance between proliferation and apoptosis is important for breast cell homeostasis. Mammographic breast density has been identified as a strong and independent risk factor for breast cancer. It seems clear that there is a difference between various hormonal treatments with regard to their effects on breast density and cell proliferation. Also, not all women respond similarly to the same treatment. Combined estrogen and progestogen therapy generally will enhance density and proliferation more than treatment with estrogen alone. Certain constitutional and hormonal factors appear to be predictive of breast reactivity. Older women with a low body mass index respond more strongly to treatment. Estrogen levels have a positive and androgens a negative association to increase in density and proliferation. A combination of increased proliferation and decreased apoptosis could be one mechanism to explain the excess risk of breast cancer during combined estrogen/progestogen treatment. Tibolone seems to have less impact on breast response than conventional hormone therapy. Efforts should be made to identify those women with an adverse response to treatment as well as therapeutic principles with the least possible influence on the breast.

Beer constituents as potential cancer chemopreventive agents

Beer is a complex alcoholic beverage made from barley (malt), hop, water and yeast. Phenolic constituents of beer are derived from malt (70-80%) and hop (20-30%). Structural classes include simple phenols, benzoic- and cinnamic acid derivatives, coumarins, catechins, di-, tri- and oligomeric proanthocyanidins, (prenylated) chalcones and flavonoids as well as alpha- and iso-alpha-acids derived from hop. Compounds belonging to different structural classes have distinct profiles of biological activity in in vitro test systems, and in combination might lead to enhanced effects. Scientific evidence has accumulated over the past 10 years pointing to the cancer preventive potential of selected hop-derived beer constituents, i.e., prenylflavonoids including xanthohumol and isoxanthohumol, and hop bitter acids. Chemopreventive activities observed with these compounds relevant to inhibition of carcinogenesis at the initiation, promotion and progression phases, as well as results from in vivo studies on metabolism, bioavailability and efficacy are summarised in this review.

Ageing, hormonal behaviour and cyclin D1 in ductal breast carcinomas

Owing to the gradual modification of breast tissue in postmenopausal women, there can be differential effects on local oestrogen receptor (ER) expression, with potential impingement on the biological behaviour of cancer cells in the ageing. A series of 45 ductal carcinoma (DC) cases were selected in postmenopausal women who were not being treated with HRT. Immunohistochemical analyses were performed for hormone receptors and Ki67 expression. Fluorescence in situ hybridisation (FISH) analysis was carried out to study CCND1 amplification. The selected population was subdivided into three groups by age and was subjected to statistical studies: linear model analysis, estimation of relative incidence (RI), multivariate analysis, and nonparametric tests were performed to investigate whether there were any links between age and molecular variables in DCs. The results show a low rate of proliferation and high ER expression in the oldest age group. In the same group a close correlation was found between high ER expression and CCN in the older age group D1 amplification (P=0.000), as was a more advanced phenotype in terms of tumour size and presence of positive lymph nodes than in the other age groups considered. The results suggest that ductal breast cancer has a favourable molecular prognosis, especially in extreme old age. In particular, there is an inverse correlation between ageing and proliferation rate despite the presence of an accentuated proliferation stimulus (high ER with CCD1 amplifications) in the oldest group relative to the other groups considered.

Menopausal Hormone Therapy After Breast Cancer: The Stockholm Randomized Trial

In 1997 two independent randomized clinical trials, Hormonal Replacement Therapy After Breast Cancer--Is It Safe? (HABITS; 434 patients) and the Stockholm trial (378 patients), were initiated in Sweden to compare menopausal hormone therapy with no menopausal hormone therapy after diagnosis of early-stage breast cancer. Much of the design of both studies was similar; however, a goal of the Stockholm protocol, not shared with the HABITS trial, was to minimize the use of progestogen combined with estrogen. The HABITS trial was prematurely stopped in December 2003, because, at a median follow-up of 2.1 years, the risk for recurrence of breast cancer among patients receiving menopausal hormone therapy was statistically significantly higher (relative hazard [RH] = 3.3, 95% confidence interval [CI] = 1.5 to 7.4) than among those receiving no treatment. In the Stockholm trial, however, at a median follow-up of 4.1 years, the risk of breast cancer recurrence was not associated with menopausal hormone therapy (RH = 0.82, 95% CI = 0.35 to 1.9). Statistically significant heterogeneity in the rate of recurrence was observed (P = .02; two-sided likelihood-ratio test) between the two studies, indicating that chance may not be the only explanation. Doses of estrogen and progestogen and treatment regimens for menopausal hormone therapy may be associated with the recurrence of breast cancer.

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.

Hormonal Factors and Breast Tumor Proliferation: Do Factors that Affect Cancer Risk also Affect Tumor Growth?

BACKGROUND

Tumor cell proliferation is one of the most significant predictors of prognosis for women with breast cancer. Personal characteristics that affect hormonal exposure have been implicated in breast tumor etiology, and it is possible that they may also influence tumor cell proliferation. We examined the association between hormone-related breast cancer risk factors and breast tumor proliferation, as reflected in two proliferation measures, Ki-67 and mitotic count.

METHODS

The study population was 484 women 40 years of age and older, who were members of a managed care organization's breast cancer screening program and were diagnosed with invasive breast cancer between 1988 and 1995. The percent of Ki-67 positive tumor cells averaged over four high powered fields (Ki-67) was log transformed and analyzed in a linear regression model. Mitotic count was dichotomized into high versus low (<or=10), and analyzed in an unconditional logistic regression model with the odds ratio (OR) as the measure of association.

RESULTS

Consistent with other studies, there was a significant trend of decreased tumor cell proliferation with increasing age ( p for trend <0.05 for both measures). Higher body weight was associated with higher Ki-67 ( p for trend <0.05), but not with higher mitotic count. We found no significant associations between any reproductive factors (age at menarche, parity, age at first birth, menopausal status and age at menopause) and either measure of tumor cell proliferation. We observed an association between reduced tumor proliferation, as measured by mitotic count and former/current use of hormone replacement therapy (HRT) in comparison to never use (adjusted OR's: former HRT use: 0.40 (95% CI 0.19-0.85); current HRT use: 0.52 (95% CI 0.26-1.04).

CONCLUSION

Certain factors related to hormonal exposure that influence breast tumor etiology, for example, age, also appear to increase tumor growth. Conversely HRT use, which clearly increases breast cancer risk, may not adversely affect, and possibly may diminish cell proliferation once tumors are established.

The process of metastasisation for breast cancer

To investigate the process of metastasis, primary clinical data and disease events such as metastases, local recurrence and survival (median follow-up 9.4 years) from the Munich Cancer Registry from 1978 to 1996 were analysed. Since metastases, even from small tumours, may be initiated before the diagnosis of the primary tumour, the growth of the primary tumour and metastasisation may be two autonomous processes. In our data, survival following metastases was almost unrelated to primary tumour size. However, the number of M1 cases and the time to metastasisation depended on the tumour diameter at diagnosis. The time from initiation of metastases to its diagnosis was estimated as 5.8 years. The growth of metastases was almost homogeneous. However, the growth time following metastasisation-depending on the metastases-free time, receptor status and histological grade-only varied by approximately a factor of 2. Local recurrence, above all, was an indicator of metastases. Furthermore, local recurrence may also have the potential to metastasise. Excess mortality due to local recurrence was estimated up to 9.3 years after diagnosis. Our hypothesised metastases model illustrates the importance of early detection, the concept of breast-conserving therapy and additional metastases from local recurrence. It highlights the benefits of optimal local therapy of the primary tumour and the limitations of systemic therapy. It also questions the use of axilla dissection and lymph node irradiation. Its generalisation to solid tumours may help to clarify many of the current controversial debates.

Breast cell proliferation in postmenopausal women during HRT evaluated through fine needle aspiration cytology

The basis of breast cancer risk associated with hormonal therapies may lie in the regulation of cell proliferation. In a prospective, double-blind, randomized study postmenopausal women were given continuous combined hormone replacement therapy (HRT) either as estradiol valerate 2 mg/dienogest 2 mg, (E2V/DNG) or estradiol 2 mg/noretisterone acetate 1 mg (E2/NETA) for 6 months. Fine needle aspiration (FNA) biopsies were used for immunocytochemical analysis of breast cell proliferation before and during treatment. From 45 women completing the study 135 biopsies were obtained. In the total material there was a more than 4-fold increase in proliferation between baseline and 3 months (p < 0.001). The mean percentage of MIB-1 positive breast cells increased from 2.2 to 9.1%. In some individual women values were as high as 25%. No further increase was recorded at 6 months. While numerical values were somewhat lower in the E2V/DNG group, there were no significant differences between treatments. There was a positive correlation between breast cell proliferation (MIB-1%) and circulating levels of both estradiol (r(s) = 0.54, p < 0.01) and estrone (r(s) = 0.53, p < 0.01) after 3 and 6 months of treatment. No correlations with other endogenous hormones, proteins or with the two exogenous progestogens dienogest and norethisterone were observed. Increased breast cell proliferation should probably be regarded as an unwanted side-effect during HRT. Means to identify those women with the most pronounced proliferative response should be developed. The FNA biopsy technique may be a useful tool to monitor and evaluate the proliferative response to HRT in the normal breasts of postmenopausal women.

Estrogen replacement therapy and cardioprotection: mechanisms and controversies

Epidemiological and case-controlled studies suggest that estrogen replacement therapy might be beneficial in terms of primary prevention of coronary heart disease (CHD). This beneficial effect of estrogens was initially considered to be due to the reduction of low density lipoproteins (LDL) and to increases in high density lipoproteins (HDL). Recent studies have shown that estrogens protect against oxidative stress and decrease LDL oxidation. Estrogens have direct effects on the arterial tissue and modulate vascular reactivity through nitric oxide and prostaglandin synthesis. While many of the effects of estrogen on vascular tissue are believed to be mediated by estrogen receptors alpha and beta, there is evidence for 'immediate non-genomic' effects. The role of HDL in interacting with 17beta-estradiol including its esterification and transfer of esterified estrogens to LDL is beginning to be elucidated. Despite the suggested positive effects of estrogens, two recent placebo-controlled clinical trials in women with CHD did not detect any beneficial effects on overall coronary events with estrogen therapy. In fact, there was an increase in CHD events in some women. Mutations in thrombogenic genes (factor V Leiden, prothrombin mutation, etc.) in a subset of women may play a role in this unexpected finding. Thus, the cardioprotective effect of estrogens appears to be more complicated than originally thought and requires more research.

Mammographic tissue, breast cancer risk, serial image analysis, and digital mammography. Part 2. Serial breast tissue change and related temporal influences

The work presented herein is the second part of a review of breast tissue-related cancer-risk research. Briefly, in part 1, the tissue-risk research is discussed. In this part, factors that influence temporal breast tissue change are reviewed. Since breast composition is correlated with some of the known risk factors, understanding these influences may provide a mechanism for measuring the dynamics of breast cancer risk. The purpose of this work is to provide support for an automated serial mammography study under way at the authors' institution, where the digital mammographic images are acquired with a full-field digital mammography imaging system. At the initiation of the serial study, it was clear that the authors did not fully understand the nature of the problem: automatically comparing similar mammographic scenes acquired at different times. The evidence indicates that there are many factors that influence breast tissue at any given time and thus have the ability to alter the associated radiographic appearance over time. In general, the topics considered herein include aging; involution; breast development; exogenous and endogenous hormonal interactions such as hormone replacement therapy, oral contraceptive use, and menstrual timing; screening sensitivity issues and interval cancers; tumor growth rates; sojourn times; and lifestyle factors such as diet and exercise. Throughout this work, commentaries and suggestive strategies for automated serial image analysis are provided.

Hormone receptors and proliferation in breast carcinomas of equivalent histologic grades in pre- and postmenopausal women

Breast cancers in younger, premenopausal women are more likely to exhibit an adverse prognostic profile (including negative steroid hormone receptors and a high rate of cellular proliferation) and poor outcome than breast cancers in postmenopausal women. It has been hypothesized that this adverse prognostic profile is a result of the higher histologic grade of breast cancers in pre- compared with post-menopausal women. To assess the association of expression of steroid hormone receptors and indicators of proliferation while controlling for histologic grade, we identified 100 infiltrating ductal carcinomas from premenopausal women 45 years of age or younger and 100 from postmenopausal women 65 years of age or older. The carcinomas were selected so that the histologic grades (low versus high) were distributed equally between the 2 groups. Estrogen receptors (ER), progesterone receptors (PR), p27(Kip1) and Ki-67 (to measure rate of proliferation) were assessed by immunohistochemistry and compared between groups. Clinical information and survival data were also analyzed. ER content was lower and proliferation was higher in carcinomas in premenopausal women (p = 0.048 and p = 0.005, respectively). By univariate analysis, p27(Kip1) and PR were not different between the groups; however, in multivariate analysis, p27(Kip1) was higher in postmenopausal women, but only in a subgroup with highly proliferative carcinomas. Overall survival was similar in the pre- and postmenopausal women. Furthermore, low p27(Kip1) and African-American ethnicity predicted a poorer overall survival in the premenopausal, but not in the postmenopausal, women in our study. After controlling for histologic grade, a lower expression of ER and a higher proliferative index were detected in breast carcinomas in premenopausal women. Therefore, some prognostic indicators, such as ER and proliferative rate, may be more closely associated with menopausal status than histologic grade. Our data also suggest that some prognostic factors are not equally effective as predictors of survival in pre- and postmenopausal women.

Mammographic density changes during different postmenopausal hormone replacement therapies

OBJECTIVE

To determine the degree of change in mammographic breast densities during different types of postmenopausal hormone replacement therapies.

DESIGN

A retrospective study.

SETTING

Ege University Hospital.

PATIENT(S)

The mammographies of 216 women on various postmenopausal hormone replacement therapies were evaluated.

INTERVENTION(S)

Estrogen alone (n = 76) or estrogen in cyclic (n = 44) or continuous (n = 61) combination with progestin or tibolone-only (n = 35) replacement therapies were used. Mammographic density was quantified according to the Wolfe classification in patients with different hormone replacement regimens.

MAIN OUTCOME MEASURE(S)

Mammographic density changes were interpreted.

RESULT(S)

An increase in mammographic density was much more common among women receiving continuous combination hormone replacement therapy 31.1% (19 of 61) than among those receiving estrogen-only 3.9% (3 of 76) treatment. There were no significant mammographic breast density changes among women receiving cyclic continuous combination hormone replacement therapy or tibolone-only treatment. The increase in density was apparent already at first visit after the start of hormone replacement therapy. In continuous combined postmenopausal hormone replacement therapy with norethisterone acetate, the increase in mammographic density was 34.1% (15 of 44), followed by medroxyprogesterone acetate 23.5% (4 of 17).

CONCLUSION(S)

Our findings show that mammographic breast density changes related to postmenopausal hormone replacement therapy are dependent on the selected hormone regimen. The continuous administration of the progestin component of the combined-hormone replacement therapy seems to effect the breast density most.

Cloning and characterization of a novel gene that is regulated by estrogen and is associated with mammary gland carcinogenesis

Estrogens play a role in mammary gland function and are implicated in mammary carcinogenesis. We report the cloning of a novel gene [steroid-sensitive gene 1 (SSG1)] that is regulated by E(2) in the rat uterus and mammary gland. The full-length SSG1 complementary DNA has an open reading frame of 1158 nucleotides encoding a putative protein of 385 amino acids. A SSG1-specific antibody recognizes a 40-kDa protein localized to myoepithelial cells of normal mammary tissue and to endothelial cells of 7,12-dimethylbenz(a)antracene-induced mammary tumors. Treatment of rats with E(2) at 1.2 or 2.4 microg/kg.day for 21 days increases SSG1 protein levels in mammary tissue by 16-fold compared with controls. Removal of E(2) after a 14-day treatment decreases SSG1 protein levels 6-fold and 3-fold at 120 and 144 h, respectively. Treatment of rats with the estrogen antagonists tamoxifen or ICI 182,780 did not affect SSG1 protein levels compared with controls. SSG1 protein levels in 7,12-dimethylbenz(a)antracene-induced rat mammary tumors were 23-fold greater than SSG1 levels in resting mammary tissue, and 8-fold higher than protein levels expressed in lactating mammary glands. We propose that SSG1 plays a role in estrogen functions, and its overexpression is correlated with mammary carcinogenesis.

Parity and mammographic breast density in relation to breast cancer risk: indication of interaction

We examined whether the harmful influence of nulliparity on breast cancer risk could be mediated by high mammographic density. Another possibility is that mammographic density and nulliparity act independently or perhaps synergistically on breast cancer risk. Our study population consisted of 129 cases and 517 controls who had been participants in the Nijmegen breast cancer screening programme for 10 years. Breast density was classified with a fully automated technique on digitized mammograms from the screening examination 10 years before diagnosis. Classification was based on the proportion of the breast that was composed of high density: < 5%, 5-25% or > 25%. Data on parity and potential confounders were obtained using a questionnaire, administered at the same examination. We found that nulliparae with low breast density (< 5%) were not at increased risk compared to parous women with low density: OR 1.1 (95% CI 0.2-5.8). Parous women with < 5% density formed the reference category throughout all analyses. The risks for parous women with 5-25% or > 25% density were 2.7 (95% CI 1.3-5.6) and 3.6 (95% CI 1.7-7.7) fold increased, respectively. However, when both factors were present (nulliparity and > or = 5% density), breast cancer risk was 7.1 times higher (95% CI 3.2-15.9). This could indicate that nulliparity and high breast density might work synergistically and that breast density is not just an explanatory factor in the influence of nulliparity on breast cancer risk. It is hypothesized that high breast density (reflecting fibro-glandular tissue with increased epithelial cell proliferation) is more susceptible to carcinogenic effects in the undifferentiated epithelial breast tissue of nulliparae than in the differentiated tissue of parous women. Since there were few data, no firm conclusions can be drawn. If these findings can be confirmed in a larger study population, however, they may have important implications for the prevention and early detection of breast cancer.

Altering the estrogenic milieu of breast cancer with a focus on the new aromatase inhibitors

Aromatase is a dual-enzyme complex that catalyzes the synthesis of estrogen from androgenic precursors. Although evidence implicates estrogens in the pathogenesis of breast cancer, recent findings suggest that deregulation of aromatase may be a crucial link between these hormones and this neoplasm. Whereas tamoxifen is the endocrine therapy of choice, selective inhibition of aromatase may be equally effective, and possibly less toxic, in the management of patients with hormone-responsive breast tumors.

Cellular responses of mammary carcinomas to aromatase inhibitors: effects of vorozole

Vorozole (Vz) is a competitive non-steroidal inhibitor of aromatase, which has been used to treat breast cancer in postmenopausal women and in various chemoprevention pre-clinical studies. Recently, we assessed the inhibitory effect of Vz on MNU-induced mammary carcinogenesis (Lubet et al., 1994), as well as on the progression of mammary tumors (Lubet et al., 1998). In this study we evaluated the effects of Vz on tumor growth, serum estradiol, cell proliferation, apoptotic and non-apoptotic cell death to determine whether any of these 'surrogate' markers might reflect the efficacy of various doses of Vz. Vz at doses of 2.5 (Hi), 0.32 (Md), and 0.08 (Lo) mg/kg body weight induced complete (100%), 60%, and 20% regression of mammary tumors, respectively. Vz at Hi and Md doses caused a decrease in serum estradiol within the first two days of treatment, and the estradiol values remained low with additional treatment for 4 and 10 days. When Vz was administered to animals bearing palpable tumors a time and dose-dependent decrease in the proliferating cells (BrdU-L1) was observed. The percentage of apoptotic cells (A1) sharply increased 2 days after initiation of Vz treatment and then decreased followed by an increase in non-apoptotic dead cells. Interestingly even the Lo dose of Vz, which was only moderately effective in suppressing tumor growth, decreased cell proliferation and increased cell death in the peripheral tumor areas at 4 and 10 days after initiation of treatment. The time- and dose-dependent alterations in various cell parameters suggest two different phases of Vz-induced cellular responses: (1) an early phase (2-4 days of treatment) with a sharp increase in apoptotic cells and decrease in proliferating cells, and (2) a later phase (10 days) with disintegration of tumor parenchyma, increase in non-apoptotic dead cells, and decrease in apoptotic cells. The dose-dependent decrease in proliferating cells and increase in apoptotic and non-apoptotic cell death in Vz-treated animals suggest that these biomarkers might be used as potential surrogate endpoints for efficacy in breast cancer chemoprevention and therapy studies with aromatase inhibitors.

New generation aromatase inhibitors in breast cancer. Weighing out potential costs and benefits

Endocrine therapy is the oldest and still one of the most effective forms of systemic therapy for breast cancer. Unfortunately, only one-third of all breast carcinomas respond to a strategy that modifies the activity of estrogen at the level of the tumour. Therefore, it is important that patients with cancer likely to respond are reliably identified. Substantial evidence indicates that tumour estrogen receptor level is the best predictor of response to hormonal therapy. Although antiestrogen therapy is still considered the endocrine modality of choice for all stages of breast cancer, there is renewed interest in finding new agents with improved therapeutic indices. The development of agents which selectively suppress aromatase, a key enzyme in estrogen biosynthesis, can be attributed not only to the importance of extraglandular aromatase activity, but also to the unparalleled success of tamoxifen. The present status, emerging roles and concerns of the new aromatase inhibitors are discussed in order to assess their potential costs and therapeutic merit.

Expression of sex steroid receptors and IGF-1 mRNA in breast tissue--effects of hormonal treatment

The mechanisms behind increased breast tissue proliferation and a possibly increased breast cancer risk in women using hormonal contraception (HC) and hormonal replacement therapy (HRT) are incompletely understood. We analyzed breast tissue from 20 premenopausal and seven postmenopausal women undergoing reduction mammoplasties for estrogen receptor (ER) and progesterone receptor (PR) content as well as mRNA levels for ER, PR and insulin-like growth factor-1 (IGF-1). The receptor values were correlated to IGF-1 mRNA concentrations and levels of steroid and peptide hormones and SHBG. In women using HC, we found significantly lower ER values (p = 0.02) but non-significantly lower ER mRNA levels compared to those in naturally cycling women. PR and PR mRNA were no different. Women on HC displayed a higher breast tissue proliferation (p = 0.05) expressed as Ki-67, MIB-1 positivity, which was correlated with IGF-1 mRNA (r(s) = 0.82, p = 0.04). Since the concentration of sex steroid receptors in breast tissue is comparatively low and steroid receptors are down-regulated during hormonal treatment, mechanisms other than direct sex steroid receptor action are likely to be present. Our results suggest a role for IGF-1 in the proliferative response of breast tissue during exogenous hormonal treatment.

10-Year results after sector resection with or without postoperative radiotherapy for stage I breast cancer: a randomized trial

PURPOSE

To study the long-term effectiveness of postoperative radiotherapy after sector resection for breast cancer in a randomized trial in which mammography is a major pathway to diagnosis.

PATIENTS AND METHODS

Three hundred eighty-one women with a unifocal breast cancer < or = 20 mm in diameter on the preoperative mammogram and without histopathologic signs of axillary metastases were treated by sector resection plus axillary dissection. Of these patients, 184 women were randomized to receive postoperative radiotherapy to the breast (XRT group), and 197 women received no further treatment (non-XRT group).

RESULTS

The local recurrence rate was 8.5% (95% confidence interval [CI], 3.9% to 13.1%) in the XRT group and 24.0% (95% CI, 17.6% to 30.4%) in the non-XRT group (P =.0001). Survival free from regional and distant recurrence was 83. 3% in the XRT group (95% CI, 77.5% to 89.1%) and 80.0% in the non-XRT group (95% CI, 73.9% to 86.1%) (P =.23). Overall survival was 77.5% in the XRT group (95% CI, 70.9% to 84.1%) and 78% in the non-XRT group (95% CI, 71.7% to 84.3%) (P =.99). A subgroup analysis suggested that women older than 55 years of age without comedo or lobular carcinomas had a low risk of local recurrence of 6.1% (95% CI, 0.1% to 9.1%) in the XRT-group and 11.0% (4.0% to 18.0%) in the non-XRT group (P =.16).

CONCLUSION

Sector resection plus radiotherapy resulted in an absolute reduction in local recurrence of 16% at 10 years compared with surgery alone. Women older than 55 years of age without comedo or lobular carcinomas may have a low risk of local recurrence. Postoperative radiotherapy was not shown to reduce distant recurrences or improve overall survival.

Mammographic breast density during hormone replacement therapy: differences according to treatment

OBJECTIVE

Our purpose was to investigate the effects of various hormone replacement regimens on mammographic breast density.

STUDY DESIGN

Mammographic density was recorded in women participating in a population-based screening program. All women were nonusers of hormone replacement therapy at first mammogram and thereafter reported continuous use of the same treatment: estrogen alone (n = 50) or estrogen in cyclic (n = 75) or continuous (n = 50) combination with progestogen. Mammographic density was quantified according to the Wolfe classification.

RESULTS

An increase in mammographic density was much more common among women receiving continuous combination hormone replacement therapy (52%) than among those receiving cyclic (13%) and estrogen-only (18%) treatment. The increase in density was apparent already at first visit after the start of hormone replacement therapy. There was little change in mammographic status during long-term follow-up.

CONCLUSION

Regimens of hormone replacement therapy were shown to have different effects on the normal breast. There is an urgent need to clarify the biologic nature and significance of a change in mammographic density during treatment and, in particular, its relation to symptoms and breast cancer risk.