Hormone replacement therapy in relation to risk of lobular and ductal breast carcinoma in middle-aged women

Is There a Special Role for Ovarian Hormones in the Pathogenesis of Lobular Carcinoma?

Lobular carcinoma represent the most common special histological subtype of breast cancer, with the majority classed as hormone receptor positive. Rates of invasive lobular carcinoma in postmenopausal women have been seen to increase globally, while other hormone receptor-positive breast cancers proportionally have not followed the same trend. This has been linked to exposure to exogenous ovarian hormones such as hormone replacement therapy. Reproductive factors resulting in increased lifetime exposure to endogenous ovarian hormones have also been linked to an increased risk of lobular breast cancer, and taken together, these data make a case for the role of ovarian hormones in the genesis and progression of the disease. In this review, we summarize current understanding of the epidemiological associations between ovarian hormones and lobular breast cancer and highlight mechanistic links that may underpin the etiology and biology.

DCIS and LCIS: Are the Risk Factors for Developing In Situ Breast Cancer Different?

Ductal carcinoma in situ (DCIS) is widely accepted as a precursor of invasive ductal carcinoma (IDC). Lobular carcinoma in situ (LCIS) is considered a risk factor for invasive lobular carcinoma (ILC), and it is unclear whether LCIS is also a precursor. Therefore, it would be expected that similar risk factors predispose to both DCIS and IDC, but not necessarily LCIS and ILC. This study examined associations with risk factors using data from 3075 DCIS cases, 338 LCIS cases, and 1584 controls aged 35-60, recruited from the UK-based GLACIER and ICICLE case-control studies between 2007 and 2012. Analysis showed that breastfeeding in parous women was protective against DCIS and LCIS, which is consistent with research on invasive breast cancer (IBC). Additionally, long-term use of HRT in post-menopausal women increased the risk of DCIS and LCIS, with a stronger association in LCIS, similar to the association with ILC. Contrary to findings with IBC, parity and the number of births were not protective against DCIS or LCIS, while oral contraceptives showed an unexpected protective effect. These findings suggest both similarities and differences in risk factors for DCIS and LCIS compared to IBC and that there may be justification for increased breast surveillance in post-menopausal women taking long-term HRT.

Current and future diagnostic and treatment strategies for patients with invasive lobular breast cancer

BACKGROUND

Invasive lobular breast cancer (ILC) is the second most common type of breast cancer after invasive breast cancer of no special type (NST), representing up to 15% of all breast cancers.

DESIGN

Latest data on ILC are presented, focusing on diagnosis, molecular make-up according to the European Society for Medical Oncology Scale for Clinical Actionability of molecular Targets (ESCAT) guidelines, treatment in the early and metastatic setting and ILC-focused clinical trials.

RESULTS

At the imaging level, magnetic resonance imaging-based and novel positron emission tomography/computed tomography-based techniques can overcome the limitations of currently used imaging techniques for diagnosing ILC. At the pathology level, E-cadherin immunohistochemistry could help improving inter-pathologist agreement. The majority of patients with ILC do not seem to benefit as much from (neo-)adjuvant chemotherapy as patients with NST, although chemotherapy might be required in a subset of high-risk patients. No differences in treatment efficacy are seen for anti-human epidermal growth factor receptor 2 (HER2) therapies in the adjuvant setting and cyclin-dependent kinases 4 and 6 inhibitors in the metastatic setting. The clinical utility of the commercially available prognostic gene expression-based tests is unclear for patients with ILC. Several ESCAT alterations differ in frequency between ILC and NST. Germline BRCA1 and PALB2 alterations are less frequent in patients with ILC, while germline CDH1 (gene coding for E-cadherin) alterations are more frequent in patients with ILC. Somatic HER2 mutations are more frequent in ILC, especially in metastases (15% ILC versus 5% NST). A high tumour mutational burden, relevant for immune checkpoint inhibition, is more frequent in ILC metastases (16%) than in NST metastases (5%). Tumours with somatic inactivating CDH1 mutations may be vulnerable for treatment with ROS1 inhibitors, a concept currently investigated in early and metastatic ILC.

CONCLUSION

ILC is a unique malignancy based on its pathological and biological features leading to differences in diagnosis as well as in treatment response, resistance and targets as compared to NST.

The Proliferative Response to p27 Down-Regulation in Estrogen Plus Progestin Hormonal Therapy is Lost in Breast Tumors

Increased proliferation and breast cancer risk has been observed in postmenopausal women receiving estrogen (E) + progestin hormone replacement therapy (HRT). Progestin action is mediated through two progesterone receptor (PR) isoforms, PRA and PRB, with unique transcriptional activity and function. The current study examines hormonal regulation of PR isoforms in the normal postmenopausal human breast and the mechanism by which progestins increase proliferation and breast cancer risk. Archival benign breast biopsies from postmenopausal and premenopausal women, and luminal breast tumor biopsies from postmenopausal women, were analyzed for regulation of PRA and PRB expression by E and E+medroxyprogesterone acetate (MPA). In the postmenopausal breast without HRT, PRA and PRB expression was decreased compared to the premenopausal breast. Both E (n = 12) and E+MPA (n = 13) HRT in the postmenopausal breast were associated with increased PRA and PRB expression, increased nuclear cyclin E expression, and decreased nuclear p27 expression compared to no HRT (n = 16). With E+MPA HRT, there was a further decrease in nuclear p27 and increased Receptor Activator of NF-kappa B Ligand (RANKL) expression compared to E-alone HRT. In luminal breast cancers, E+MPA HRT (n = 6) was also associated with decreased nuclear expression of the cell cycle inhibitor p27 compared to E HRT (n = 6), but was not associated with increased proliferation. These results suggest that p27 mediates progestin-induced proliferation in the normal human breast and that regulation of this proliferative response by E+MPA is lost in breast tumors.

Prognostic Value of MammaPrint® in Invasive Lobular Breast Cancer

BACKGROUND

MammaPrint® is a microarray-based gene expression test cleared by the US Food and Drug Administration to assess recurrence risk in early-stage breast cancer, aimed to guide physicians in making neoadjuvant and adjuvant treatment decisions. The increase in the incidence of invasive lobular carcinomas (ILCs) over the past decades and the modest representation of ILC in the MammaPrint development data set calls for a stratified survival analysis dedicated to this specific subgroup.

STUDY AIM

The current study aimed to validate the prognostic value of the MammaPrint test for breast cancer patients with early-stage ILCs.

MATERIALS AND METHODS

Univariate and multivariate survival associations for overall survival (OS), distant metastasis-free interval (DMFI), and distant metastasis-free survival (DMFS) were studied in a study population of 217 early-stage ILC breast cancer patients from five different clinical studies.

RESULTS AND DISCUSSION

A significant association between MammaPrint High Risk and poor clinical outcome was shown for OS, DMFI, and DMFS. A subanalysis was performed on the lymph node-negative study population. In the lymph node-negative study population, we report an up to 11 times higher change in the diagnosis of an event in the MammaPrint High Risk group. For DMFI, the reported hazard ratio is 11.1 (95% confidence interval = 2.3-53.0).

CONCLUSION

Study results validate MammaPrint as an independent factor for breast cancer patients with early-stage invasive lobular breast cancer. Hazard ratios up to 11 in multivariate analyses emphasize the independent value of MammaPrint, specifically in lymph node-negative ILC breast cancers.

Menopausal hormone therapy and breast cancer: what is the true size of the increased risk?

BACKGROUND

Menopausal hormone therapy (MHT) increases breast cancer risk; however, most cohort studies omit MHT use after enrolment and many infer menopausal age.

METHODS

We used information from serial questionnaires from the UK Generations Study cohort to estimate hazard ratios (HRs) for breast cancer among post-menopausal women with known menopausal age, and examined biases induced when not updating data on MHT use and including women with inferred menopausal age.

RESULTS

Among women recruited in 2003-2009, at 6 years of follow-up, 58 148 had reached menopause and 96% had completed a follow-up questionnaire. Among 39 183 women with known menopausal age, 775 developed breast cancer, and the HR in relation to current oestrogen plus progestogen MHT use (based on 52 current oestrogen plus progestogen MHT users in breast cancer cases) relative to those with no previous MHT use was 2.74 (95% confidence interval (CI): 2.05-3.65) for a median duration of 5.4 years of current use, reaching 3.27 (95% CI: 1.53-6.99) at 15+ years of use. The excess HR was underestimated by 53% if oestrogen plus progestogen MHT use was not updated after recruitment, 13% if women with uncertain menopausal age were included, and 59% if both applied. The HR for oestrogen-only MHT was not increased (HR=1.00; 95% CI: 0.66-1.54).

CONCLUSIONS

Lack of updating MHT status through follow-up and inclusion of women with inferred menopausal age is likely to result in substantial underestimation of the excess relative risks for oestrogen plus progestogen MHT use in studies with long follow-up, limited updating of exposures, and changing or short durations of use.

Postmenopausal Hormone Therapy and Breast Cancer Prognostic Characteristics: A Linkage between Nationwide Registries

BACKGROUND

The effects of use of different types of hormone therapy on breast cancer risk according to prognostic factors are largely unknown.

METHODS

We linked data from the Norwegian Prescription Database and the Cancer Registry of Norway during 2004 to 2009 on all women ages 45 to 79 years (N = 686,614). We estimated rate ratios and 95% confidence intervals for breast cancer in relation to hormone therapy using Poisson regression.

RESULTS

During an average 4.8 years of follow-up, 7,910 invasive breast cancers were diagnosed. Compared with nonusers of hormone therapy, users of estradiol and tibolone were more likely to be diagnosed with grade I, lymph node-negative, and estrogen receptor-positive (ER⁺)/progesterone receptor-positive (PR⁺) tumors. However, compared with nonusers, users of the most common estrogen and progestin combinations [estradiol-norethisterone acetate (NETA) preparations (Kliogest, Activelle or Trisekvens)] were at a 4- to 5-fold elevated risk of grade I tumors, 3-fold elevated risk of lymph node-negative tumors, and 3- to 4-fold elevated risk of ER⁺/PR⁺ tumors. Importantly, estradiol-NETA users were also at a 2- to 3-fold increased risk of medium differentiated (grade II) tumors and tumors with lymph node involvement.

CONCLUSIONS

Use of oral estradiol, tibolone, and estradiol-NETA predominantly increases the risk of breast cancer with favorable prognosis characteristics. However, use of estradiol-NETA preparations also increases the risk of breast cancers with less favorable characteristics.

IMPACT

The hormone therapy preparations most commonly used in the Nordic countries are associated with both breast cancers with good and less favorable prognosis characteristics. Cancer Epidemiol Biomarkers Prev; 25(11); 1464-73. ©2016 AACR.

Progestin-mediated activation of MAPK and AKT in nuclear progesterone receptor negative breast epithelial cells: The role of membrane progesterone receptors

Progesterone (P4), a steroid produced during estrous cycles and gestation for maintenance of pregnancy, also plays key roles in breast development to allow lactation post-parturition. Progestins (P4 and related steroids) are also implicated in breast cancer etiology. Hormone replacement therapy containing both estrogen and progestins increases breast cancer incidence while estrogen hormone therapy lowers breast cancer risk. P4 signaling via nuclear P4 receptors (PRs) has been extensively studied in breast cancer, however, progestin signaling via non-classical membrane bound progestin receptors (MPRs and PGRMC1) remains unclear. Moreover, P4 metabolites and synthetic progestins may bind membrane progestin receptors. We hypothesized that PR-negative breast epithelial cells express non-classical progestin receptors, which activate intracellular signaling pathways differently depending on nature of progestin. Therefore, our objectives for the current study were to determine expression of MPRs and PGRMC1 in two PR-negative non-tumorigenic breast epithelial cell lines, assess progestin-mediated signaling and biological functions. We determined five MPR isoforms and PGRMC1 were present in MCF10A cells and all progestin receptors but MPRβ in MCF12A cells. MCF10A and MCF12A cells were treated with P4, select P4 metabolites (5αP and 3αHP), medroxyprogesterone acetate (MPA), or a specific MPR-Agonist (MPR-Ag) and phosphorylation of ERK, p38, JNK, and AKT was characterized following treatment. To our knowledge this is the first report of ERK and JNK activation in MCF10A and MCF12A cells with P4, P4 metabolites, MPA, and MPR-Ag. Activation of ERK and JNK in cells treated with MPR-Ag implicates MPRs may serve as the receptors responsible for their activation. In contrast, p38 activation varied with cell type and with progestin treatment. P4 and MPA promoted AKT phosphorylation in the MCF12A cell line only whereas no activation was observed in MCF10A cells. Interestingly, cellular proliferation increased in MCF10A cells treated with MPA or 5αP, while MPR-Ag tended to slightly decrease proliferation. Collectively, our data highlights the importance of investigating the effects of synthetic progestins in breast cancer biology. Our results add to the understanding that various progestins have on breast epithelial cells and underscores the importance of considering both membrane bound receptors and progestin type in breast cancer development.

Progesterone receptor membrane component 1 promotes survival of human breast cancer cells and the growth of xenograft tumors

Triple negative breast cancers (TNBCs) are highly aggressive and grow in response to sex steroid hormones despite lacking expression of the classical estrogen (E2) and progesterone (P4) receptors. Since P4 receptor membrane component 1 (PGRMC1) is expressed in breast cancer tumors and is known to mediate P4-induced cell survival, this study was designed to determine the expression of PGRMC1 in TNBC tumors and the involvement of PGRMC1 in regulating proliferation and survival of TNBC cells in vitro and the growth of TNBC tumors in vivo. For the latter studies, the MDA-MB-231 (MDA) cell line derived from TNBC was used. These cells express PGRMC1 but lack expression of the classical P4 receptor. A lentiviral-based shRNA approach was used to generate a stably transfected PGRMC1-deplete MDA line for comparison to the PGRMC1-intact MDA line. The present studies demonstrate that PGRMC1: 1) is expressed in TNBC cells; 2) mediates the ability of P4 to suppress TNBC cell mitosis in vitro; 3) is required for P4 to reduce the apoptotic effects of doxorubicin in vitro; and 4) facilitates TNBC tumor formation and growth in vivo. Taken together, these findings indicate that PGRMC1 plays an important role in regulating the growth and survival of TNBC cells in vitro and ultimately in the formation and development of these tumors in vivo. Thus, PGRMC1 may be a therapeutic target for TNBCs.

Alcohol and breast cancer tumor subtypes in a Spanish Cohort

Although alcohol intake is an established risk factor for overall breast cancer, few studies have looked at the relationship between alcohol use and breast cancer risk by the four major subtypes of breast cancer and very few data exist in the alcohol-breast cancer relationship in Spanish women. A population-based case-control study was conducted in Galicia, Spain. A total of 1766 women diagnosed with invasive breast cancer between 1997 and 2014 and 833 controls participated in the study. Data on demographics, breast cancer risk factors, and clinico-pathological characteristics were collected. We examined the alcohol-breast cancer association according to the major breast cancer subtypes [hormone-receptor-positive, HER2-negative (luminal A); hormone-receptor-positive, HER2-positive (luminal B); hormone-receptor-negative, HER2-negative (TNBC); and hormone-receptor-negative, HER2-positive (HER2 overexpressing)] as well as grade and morphology in Spanish women. With the exception of HER2 overexpressing, the risk of all subtypes of breast cancer significantly increased with increasing alcohol intake. The association was similar for hormonal receptor positive breast cancer, i.e., luminal A and luminal B breast cancer (odds ratio, OR 2.16, 95 % confidence interval, CI 1.55–3.02; and OR 1.98, 95 % CI 1.11–3.53, respectively), and for TNBC (TNBC: OR 1.93, 95 % CI 1.07–3.47). The alcohol-breast cancer association was slightly more pronounced among lobular breast cancer (OR 2.76, 95 % CI 1.62–4.69) than among ductal type breast cancers (OR 2.21, 95 % CI 1.61–3.03). In addition, significant associations were shown for all grades, I, II and III breast cancer (OR 1.98, 95 % CI 1.26–3.10; OR 2.34, 95 % CI 1.66–3.31; and OR 2.16, 95 % CI 1.44–3.25 for Grades I, II and III, respectively). To our knowledge, this is the first study to examine the association of breast cancer subtypes and alcohol intake in Spanish women. Our findings indicate that breast cancer risk increased with increasing alcohol intakes for three out of the four major subtypes of breast cancer. The association was similar for hormonal receptor positive breast cancer, i.e., luminal A and luminal B breast cancer, and for TNBC. The association seemed to be slightly more pronounced for lobular than ductal breast cancers. No differences were detected by grade.

Progesterone-induced stimulation of mammary tumorigenesis is due to the progesterone metabolite, 5α-dihydroprogesterone (5αP) and can be suppressed by the 5α-reductase inhibitor, finasteride

Progesterone has long been linked to breast cancer but its actual role as a cancer promoter has remained in dispute. Previous in vitro studies have shown that progesterone is converted to 5α-dihydroprogesterone (5αP) in breast tissue and human breast cell lines by the action of 5α-reductase, and that 5αP acts as a cancer-promoter hormone. Also studies with human breast cell lines in which the conversion of progesterone to 5αP is blocked by a 5α-reductase inhibitor, have shown that the in vitro stimulation in cell proliferation with progesterone treatments are not due to progesterone itself but to the metabolite 5αP. No similar in vivo study has been previously reported. The objective of the current studies was to determine in an in vivo mouse model if the presumptive progesterone-induced mammary tumorigenesis is due to the progesterone metabolite, 5αP. BALB/c mice were challenged with C4HD murine mammary cells, which have been shown to form tumors when treated with progesterone or the progestin, medroxyprogesterone acetate. Cells and mice were treated with various doses and combinations of progesterone, 5αP and/or the 5α-reductase inhibitor, finasteride, and the effects on cell proliferation and induction and growth of tumors were monitored. Hormone levels in serum and tumors were measured by specific RIA and ELISA tests. Proliferation of C4HD cells and induction and growth of tumors was stimulated by treatment with either progesterone or 5αP. The progesterone-induced stimulation was blocked by finasteride and reinstated by concomitant treatment with 5αP. The 5αP-induced tumors expressed high levels of ER, PR and ErbB-2. Hormone measurements showed significantly higher levels of 5αP in serum from mice with tumors than from mice without tumors, regardless of treatments, and 5αP levels were significantly higher (about 4-fold) in tumors than in respective sera, while progesterone levels did not differ between the compartments. The results indicate that the stimulation of C4HD tumor growth in BALB/c mice treated with progesterone is due to the progesterone metabolite 5αP formed at elevated levels in mammary cells as a result of the 5α-reductase action on progesterone. The results provide the first in vivo demonstration that stimulation of breast cell tumorigenesis and tumor growth accompanying progesterone treatment is due to the progesterone metabolite 5αP, and that breast tumorigenesis can be blocked with the 5α-reductase inhibitor, finasteride.

Lobular breast cancer: incidence and genetic and non-genetic risk factors

While most invasive breast cancers consist of carcinomas of the ductal type, about 10% are invasive lobular carcinomas. Invasive lobular and ductal carcinomas differ with respect to risk factors. Invasive lobular carcinoma is more strongly associated with exposure to female hormones, and therefore its incidence is more subject to variation. This is illustrated by US figures during the 1987 to 2004 period: after 12 years of increases, breast cancer incidence declined steadily from 1999 to 2004, reflecting among other causes the decreasing use of menopausal hormone therapy, and these variations were stronger for invasive lobular than for invasive ductal carcinoma. Similarly, invasive lobular carcinoma is more strongly associated with early menarche, late menopause and late age at first birth. As for genetic risk factors, four high-penetrance genes are tested in clinical practice when genetic susceptibility to breast cancer is suspected, BRCA1, BRCA2, TP53 and CDH1. Germline mutations in BRCA1 and TP53 are predominantly associated with invasive ductal carcinoma, while BRCA2 mutations are associated with both ductal and lobular cancers. CDH1, the gene coding for the E-cadherin adhesion protein, is of special interest as mutations are associated with invasive lobular carcinoma, but never with ductal carcinoma. It was initially known as the main susceptibility gene for gastric cancer of the diffuse type, but the excess of breast cancers of the lobular type in CDH1 families led researchers to identify it also as a susceptibility gene for invasive lobular carcinoma. The risk of invasive lobular carcinoma is high in female mutation carriers, as about 50% are expected to develop the disease. Carriers must therefore undergo intensive breast cancer screening, with, for example, yearly magnetic resonance imaging and mammogram starting at age 30 years.

Invasive lobular breast cancer and its variants: how special are they for systemic therapy decisions?

The WHO classification of breast tumors distinguishes, besides invasive breast cancer 'of no special type' (former invasive ductal carcinoma, representing 60-70% of all breast cancers), 30 special types, of which invasive lobular carcinoma (ILC) is the most common (5-15%). We review the literature on (i) the specificity and heterogeneity of ILC biology as documented by various analytical techniques, including the results of molecular testing for risk of recurrence; (ii) the impact of lobular histology on prediction of prognosis and effect of systemic therapies in patients. Though it is generally admitted that ILC has a better prognosis than IDC, is endocrine responsive, and responds poorly to chemotherapy, currently available data do not unanimously support these assumptions. This review demonstrates some lack of specific data and a need for improving clinical research design to allow oncologists to make informed systemic therapy decisions in patients with ILC. Importantly, future studies should compare various endpoints in ILC breast cancer patients among the group of hormonosensitive breast cancer.

Use of menopausal hormone therapy and risk of ductal and lobular breast cancer among women 55-74 years of age

The Women's Health Initiative (WHI) randomized trials found that use of combined estrogen and progestin menopausal hormone therapy (CHT) increases breast cancer risk, but use of unopposed estrogen hormone therapy (EHT) does not. However, several questions regarding the impact of hormone use on risk of different types of breast cancer and what thresholds of use confer elevations in risk remain. We conducted a population-based case-control study among women 55-74 years of age to assess the association between menopausal hormone use and risk of invasive ductal and invasive lobular breast carcinomas. Associations were evaluated using polytomous logistic regression and analyses included 880 ductal cases, 1,027 lobular cases, and 856 controls. Current EHT and CHT use were associated with 1.6-fold [95 % confidence interval (CI): 1.1-2.2] and 2.3-fold (95 % CI: 1.7-3.2) increased risks of lobular breast cancer, respectively, but neither was associated with risk of ductal cancer. Lobular cancer risk was increased after 9 years of EHT use, but after only 3 years of CHT use. Evidence across more than a dozen studies indicates that lobular carcinoma is the type of breast cancer most strongly influenced by menopausal hormones. Here, we characterize what thresholds of duration of use of both EHT and CHT that confer elevations in risk. Despite the rapid decline in hormone therapy use the WHI results were published, study of the hazards associated with these medications remains relevant given the estimated 38 million hormone therapy prescriptions that are still filled in the United States annually.

Body mass index and breast cancer risk according to postmenopausal estrogen-progestin use and hormone receptor status

To assess the joint relationships among body mass index, menopausal status, and breast cancer according to breast cancer subtype and estrogen-progestin medication use, we conducted a meta-analysis of 89 epidemiologic reports published in English during 1980-2012 identified through a systematic search of bibliographic databases. Pooled analysis yielded a summary risk ratio of 0.78 (95% confidence interval (CI): 0.67, 0.92) for hormone receptor-positive premenopausal breast cancer associated with obesity (body mass index (weight (kg)/height (m)(2)) ≥30 compared with <25). Obesity was associated with a summary risk ratio of 1.39 (95% CI: 1.14, 1.70) for receptor-positive postmenopausal breast cancer. For receptor-negative breast cancer, the summary risk ratios of 1.06 (95% CI: 0.70, 1.60) and 0.98 (95% CI: 0.78, 1.22) associated with obesity were null for both premenopausal and postmenopausal women, respectively. Elevated postmenopausal breast cancer risk ratios associated with obesity were limited to women who never took estrogen-progestin therapy, with risk ratios of 1.42 (95% CI: 1.30, 1.55) among never users and 1.18 (95% CI: 0.98, 1.42) among users; too few studies were available to examine this relationship according to receptor subtype. Future research is needed to confirm whether obesity is unrelated to receptor-negative breast cancer in populations of postmenopausal women with low prevalence of hormone medication use.

Invasive lobular carcinoma of the breast: patient response to systemic endocrine therapy and hormone response in model systems

Invasive lobular carcinoma of the breast (ILC) represents 10-15% of all newly diagnosed breast cancers, affecting ∼30,000 women annually in the United States. However, ILC is critically understudied as a breast cancer subtype. Though the vast majority of ILC are estrogen receptor-positive and present with overall favorable biomarkers, ILC patients do not benefit from improved outcomes versus other breast cancer patients. Patient outcomes, in particular in response to endocrine therapies, are not well understood in ILC, due in large part to the lack of prospective identification in large clinical trials. Further, there is a lack of laboratory models to study cell signaling, hormone response, and endocrine resistance in ILC. In this review, we provide an overview of clinicopathological features of ILC tumors, discuss issues with clinical management, and highlight the disconnect between ILC biomarkers and patient outcomes. We review currently available data on ILC patient outcomes, with a focus on response to endocrine therapy. Additionally, we describe currently available laboratory models for understanding hormone response in ILC cells, and review current data on these model systems. The promise for new insight into ILC, based on extensive representation of the disease in recent large scale genomic studies, is also discussed. Increasing understanding of endocrine response in ILC represents a critical area for future research to improve patient outcomes for this understudied breast cancer subtype.

Estrogen switches pure mucinous breast cancer to invasive lobular carcinoma with mucinous features

Mucinous breast cancer (MBC) is mainly a disease of postmenopausal women. Pure MBC is rare and augurs a good prognosis. In contrast, MBC mixed with other histological subtypes of invasive disease loses the more favorable prognosis. Because of the relative rarity of pure MBC, little is known about its cell and tumor biology and relationship to invasive disease of other subtypes. We have now developed a human breast cancer cell line called BCK4, in which we can control the behavior of MBC. BCK4 cells were derived from a patient whose poorly differentiated primary tumor was treated with chemotherapy, radiation and tamoxifen. Malignant cells from a recurrent pleural effusion were xenografted in mammary glands of a nude mouse. Cells from the solid tumor xenograft were propagated in culture to generate the BCK4 cell line. Multiple marker and chromosome analyses demonstrate that BCK4 cells are human, near diploid and luminal, expressing functional estrogen, androgen, and progesterone receptors. When xenografted back into immunocompromised cycling mice, BCK4 cells grow into small pure MBC. However, if mice are supplemented with continuous estradiol, tumors switch to invasive lobular carcinoma (ILC) with mucinous features (mixed MBC), and growth is markedly accelerated. Tamoxifen prevents the expansion of this more invasive component. The unexpected ability of estrogens to convert pure MBC into mixed MBC with ILC may explain the rarity of the pure disease in premenopausal women. These studies show that MBC can be derived from lobular precursors and that BCK4 cells are new, unique models to study the phenotypic plasticity, hormonal regulation, optimal therapeutic interventions, and metastatic patterns of MBC.

Membrane progesterone receptors (mPRs) mediate progestin induced antimorbidity in breast cancer cells and are expressed in human breast tumors

Membrane progesterone receptors (mPRs) have been detected in breast cancer cells and tissues, but their roles in cancer progression remain unclear. Here, we demonstrate the localization, signaling, and antiapoptotic actions of mPRs in two nuclear progesterone receptor (PR)-negative breast cancer cell lines, SKBR3 and MDA-MB-468 (MB468), and mPR expression in human breast tumor biopsies. mPRα, mPRβ, and mPRγ subtypes were detected in both cell lines as well as in breast tumor tissues from 13 individuals irrespective of nuclear steroid receptor expression. Competitive receptor binding studies with a selective PR ligand, R5020, and an mPR agonist, Org OD 02-0 confirmed the presence of functional mPRs on both cancer cell lines. Progesterone treatment of either cell line caused rapid activation of an inhibitory G protein, as well as activation of p42/44 MAP kinase. Treatment with progesterone or Org OD 02-0 significantly decreased cell death and apoptosis in response to serum starvation, whereas testosterone, 17β-estradiol, dexamethasone, and R5020 and RU486 were ineffective. Progesterone treatment of MB468 cells also increased mitochondrial membrane potential and Akt activity, but no decrease in caspase 3 activity was observed. Knockdown of mPRα expression in MB468 cells by siRNA transfection blocked the inhibitory effects of progesterone on cell death. The results indicate that progesterone can act through mPRs to inhibit apoptosis in breast cancer cells. The involvement of mPRs in the development or progression of breast tumor growth through inhibition of cell death is an intriguing possibility and requires further investigation.

Effects of omega-3 fatty acids on progestin stimulation of invasive properties in breast cancer

Clinical studies have shown that progestins increase breast cancer risk in hormone replacement therapy, while we and others have previously reported that progestins stimulate invasive properties in progesterone receptor (PR)-rich human breast cancer cell lines. Based on others' reports that omega-3 fatty acids inhibit metastatic properties of breast cancer, we have reviewed the literature for possible connections between omega-3 fatty-acid-driven pathways and progestin-stimulated pathways in an attempt to suggest theoretical mechanisms for possible omega-3 fatty acid inhibition of progestin stimulation of breast cancer invasion. We also present some data suggesting that fatty acids regulate progestin stimulation of invasive properties in PR-rich T47D human breast cancer cells, and that an appropriate concentration of the omega-3 fatty acid eicosapentaenoic acid inhibits progestin stimulation of invasive properties. It is hoped that focus on the inter-relationship between pathways by which omega-3 fatty acids inhibit and progestins stimulate breast cancer invasive properties will lead to further in vitro, in vivo, and clinical studies testing the hypothesis that omega-3 fatty acids can inhibit progestin stimulation of invasive properties in breast cancer, and ameliorate harmful effects of progestins which occur in combined progestin-estrogen hormone replacement therapy.

Perspectives of breast cancer etiology: synergistic interaction between smoking and exogenous hormone use

To explore breast cancer etiology, literature was searched using Medline. We explored the 1) plausibility of smoking in breast carcinogenesis; 2) physiological properties, susceptibility windows, and exposure timing of breast cells; 3) role of exogenous hormones in breast carcinogenesis; 4) biological mechanism of synergistic interactions between smoking and exogenous hormones in breast carcinogenesis; and 5) evidence from epidemiologic studies and the fitted secular trend between smoking rate, exogenous hormone use, and breast cancer incidence in past decades. We deduced that exogenous hormone use per se is not a significant cause and its association with breast cancer is distorted by chronic exposure to environmental carcinogens, especially smoking. We hypothesize that smoking is one of the causes of breast cancer and that this causality is strengthened by synergistic interaction between smoking and exogenous hormone use. Physicians should be cautious of prescribing exogenous hormones for those with chronic exposure to environmental carcinogens to prevent breast cancer.

The contribution of postmenopausal hormone use cessation to the declining incidence of breast cancer

The striking decline in United States breast cancer incidence since 2002 has been widely attributed to a reduction in postmenopausal hormone use, yet very little analysis has been conducted to quantify the contribution of changes in hormone use to the declining trend. We used literature-based estimates of the relative risk and the changing prevalence of hormone use to estimate the impact of hormone use on the decline in breast cancer incidence between 2002 and 2003 among women aged 40-79. For the base case of a 44% decline in hormone use and a relative risk for current use of 1.5, we estimated that 43% of the decline in incidence was attributable to hormone use. By exploring a range of parameter values, we found that high, unlikely values of the relative risk (i.e., ≥ 2.25) and/or the percent decline in hormone use (i.e., ≥ 75%) would be required to account for 100% of the observed decline in breast cancer incidence. We conclude that hormone use is unlikely to account for more than half of the observed decline in breast cancer incidence between 2002 and 2003. Further efforts are needed to quantify the potential contributions of other factors, such as the plateau in screening mammography utilization.

Late age at first full term birth is strongly associated with lobular breast cancer

BACKGROUND

Late age at first full-term birth and nulliparity are known to increase breast cancer risk. The frequency of these risk factors has increased in recent decades.

METHODS

The purpose of this population-based case-control study was to examine associations between parity, age at first birth (AFB), and specific histological subtypes of breast cancer. Women with breast cancer were identified from cancer registries in Wisconsin, Massachusetts, and New Hampshire. Control subjects were randomly selected from population lists. Interviews collected information on reproductive histories and other risk factors. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of ductal, lobular, and mixed ductal-lobular breast cancer diagnosis in association with AFB and nulliparity.

RESULTS

AFB ≥30 years was associated with a 2.4-fold increase in risk of lobular breast cancer compared with AFB <20 years (OR, 2.4; 95% CI, 1.9-2.9). The association was less pronounced for ductal breast cancer (OR, 1.3; 95% CI, 1.2-1.4). Nulliparity was associated with increased risk for all breast cancer subtypes, compared with women with AFB <20 years, but the association was stronger for lobular (OR, 1.7; 95% CI, 1.3-2.2) than for ductal (OR, 1.2; 95% CI, 1.1-1.3) subtypes (P = .004). The adverse effects of later AFB was stronger with obesity (P = .03) in lobular, but not ductal, breast cancer.

CONCLUSIONS

Stronger associations observed for late AFB and nulliparity suggest that these factors preferentially stimulate growth of lobular breast carcinomas. Recent temporal changes in reproductive patterns and rates of obesity may impact the histological presentation of breast cancer.

Alcohol consumption and risk of postmenopausal breast cancer by subtype: the women's health initiative observational study

BACKGROUND

Alcohol consumption is a well-established risk factor for breast cancer. This association is thought to be largely hormonally driven, so alcohol use may be more strongly associated with hormonally sensitive breast cancers. Few studies have evaluated how alcohol-related risk varies by breast cancer subtype.

METHODS

We assessed the relationship between self-reported alcohol consumption and postmenopausal breast cancer risk among 87 724 women in the Women's Health Initiative Observational Study prospective cohort from 1993 through 1998. Multivariable adjusted Cox regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). All statistical tests were two-sided.

RESULTS

A total of 2944 invasive breast cancer patients were diagnosed during follow-up through September 15, 2005. In multivariable adjusted analyses, alcohol consumption was positively related to risk of invasive breast cancer overall, invasive lobular carcinoma, and hormone receptor-positive tumors (all P(trend) ≤ .022). However, alcohol consumption was more strongly related to risk of certain types of invasive breast cancer compared with others. Compared with never drinkers, women who consumed seven or more alcoholic beverages per week had an almost twofold increased risk of hormone receptor-positive invasive lobular carcinoma (HR = 1.82; 95% CI = 1.18 to 2.81) but not a statistically significant increased risk of hormone receptor-positive invasive ductal carcinoma (HR = 1.14; 95% CI = 0.87 to 1.50; difference in HRs per drink per day among current drinkers = 1.15; 95% CI = 1.01 to 1.32, P = .042). The absolute rates of hormone receptor-positive lobular cancer among never drinkers and current drinkers were, 5.2 and 8.5 per 10 000 person-years, respectively, whereas for hormne receptor-positive ductal cancer they were 15.2 and 17.9 per 10 000 person-years, respectively.

CONCLUSIONS

Alcohol use may be more strongly associated with risk of hormone-sensitive breast cancers than hormone-insensitive subtypes, suggesting distinct etiologic pathways for these two breast cancer subtypes.

Factors that influence the incidence of breast cancer in Arica, Chile (Review)

Breast cancer is a common disease estimated to occur in 1 in 9 women over their lifetime. Epidemiological research has identified a number of risk factors for breast cancer. Racial and ethnic differences in breast cancer mortality rates have been difficult to ascertain. The present review reports that there was an increase in the incidence of breast cancer in Arica, Chile, from 1997 to 2007, particularly in 2005, reaching 55.1% per 100,000 women, while the percentage decreased in 2006 and 2007. A greater percentage of breast cancer was found in individuals between 46 and 65 years of age when the population was distributed by age. The Indian population, Aymara, had only a 13.9% incidence of the disease. The incidence for breast cancer for patients with no family background reached approximately 88%, with or without Indian ethnicity, and 98.4% of these women did not have prior hormonal therapy. When the stage of the disease and the number of pregnancies were considered, results showed that there was an increase in the progression of the disease from stage I to stage III in women that had 1-3 pregnancies. Results also showed that 20.9 and 33.2% who received prior tamoxifen treatment were in stages I and IIA, respectively. The breast cancer incidence reached 42.4% when patients had a sister with the disease. It can be concluded that important differences in the risk factors of breast cancer should be identified in the future for a comparison with other biological factors, such as genetic and molecular factors. This may provide greater insight into breast cancer aetiology in different populations.

Risk factors for ductal, lobular, and mixed ductal-lobular breast cancer in a screening population

BACKGROUND

Biological distinctions between histologic subtypes of breast cancer suggest etiologic differences, although few studies have been powered to examine such differences. We compared associations between several factors and risk of ductal, lobular, and mixed ductal-lobular breast cancers.

METHODS

We used risk factor data from the Breast Cancer Surveillance Consortium for 3,331,744 mammograms on 1,211,238 women, including 19,119 women diagnosed with invasive breast cancer following mammography (n = 14,818 ductal, 1,602 lobular, and 1,601 mixed ductal-lobular). Histologic subtype-specific risk factor associations were evaluated using Cox regression.

RESULTS

Significant positive associations with family history and breast density were similar across subtypes. Hormone therapy use was associated with increased risk of all subtypes, but was most strongly associated with lobular cancer [hazard ratio (HR) = 1.46; 95% confidence interval (CI), 1.25-1.70]. Relative to nulliparous women, parous women had lower risk of ductal and mixed but not lobular cancers (HR = 0.80; 95% CI, 0.76-0.84; HR = 0.79; 95% CI, 0.68-0.93; HR = 0.96; 95% CI, 0.81-1.15, respectively). Late age at first birth was associated with increased risk of all subtypes.

CONCLUSIONS

Similarities in risk factor associations with ductal, lobular, and mixed breast cancer subtypes were more pronounced than differences. Distinctions between subtype-specific associations were limited to analyses of hormone therapy use and reproductive history.

IMPACT

The results of this study indicate that the strongest risk factors for breast cancer overall (that is, family history and breast density) are not histologic subtype specific. Additional studies are needed to better characterize subtype-specific associations with genetic, hormonal, and nonhormonal factors.

[Lobular intra-epithelial neoplasia: atypical lobular hyperplasia and lobular carcinoma in situ]

OBJECTIVE

To review main knowledge about lobular intra-epithelial neoplasia with special interest for daily practice management.

MAIN RESULTS

Intra-epithelial lobular neoplasias (ILN) are non invasive proliferations within the terminal ducto-lobular unit of monomorphic loosely cohesive small cells. A lack of expression of the E-cadherin adhesion molecule is often observed as in invasive lobular breast cancer. ILN are infrequent, however, a rise in incidence partly, due to the generalization of mammographic screening, is observed. Actually ILN are usually asymptomatic and diagnosed after breast biopsy for unspecified microcalcifications. ILN are associated with an increased risk of breast cancer that persists over 20 years after the initial diagnosis. The average risk is 4.2 % for the ipsilateral breast and 3,5 % for the controlateral breast. However, a great variability in the risk estimation is observed between the studies. There is no consensus on how to treat ILN. Surgical options have varied from biopsy to bilateral mastectomy. Current tendency is favouring lumpectomy.

Hormone replacement therapy (HRT), breast cancer and tumor pathology

Within an average observation period of 5-6 years, several clinical trials reported an increased risk of breast cancer due to hormone replacement therapy (HRT). However, it remains disputable, whether the increased rate of breast cancers detected within the given time frame is indeed due to newly induced tumors and thus constitutes HRT-initiated primary breast cancers. Onco-pathologically speaking it appears more likely that HRT stimulates the growth of already existing small tumor nests which - due to their small size - would otherwise go undiagnosed. The major arguments are: In summary, HRT is hence more likely to be a tumor promoter than a de novo-inducer of breast cancers.

[Carcinogenesis theory based on estrogen deficiency]

Earlier, estrogens were considered simply the most important hormones involved in female physiology and reproduction. Nowadays it has become familiar that they have pivotal roles in gene regulation of cell differentiation and proliferation. There are many contradictions concerning the associations of female sexual steroids and cancer. Cancers of the highly estrogen dependent organs are in the forefront of tumors as they are regarded as hormone associated ones. However, re-evaluation of earlier results supporting the carcinogenic capacity of estrogen exhibited many shortcomings and controversies. Recently, the clinical studies on hormone replacement therapy in postmenopausal women justified beneficial anticancer effects in several organs even in the female breast. The newly revealed association between estrogen deficiency and oral cancer risk also means a contradiction of the traditional concept of estrogen-induced cancer. Distinction between cancers of moderately and highly estrogen dependent tumors can be based on their different epidemiological features. The vast majority of the so-called smoking associated malignancies of the moderately estrogen dependent organs occur typically in the late postmenopausal life of women when the ovarian estrogen production is fairly decreased. However cancers of the highly estrogen dependent organs such as breast, endometrium and ovary exhibit both premenopausal and postmenopausal occurrence. In spite of the different epidemiological data of these two groups of cancers the mechanism of gene regulation disorder in the background of tumor initiation cannot act through quite opposite pathways. This suggests that in moderately estrogen sensitive organs a serious, in the highly estrogen dependent sites even a mild estrogen deficiency is enough to provoke gene regulation disorders. The new findings both on smoking associated and hormone related cancers might lead to the same conversion; not estrogen but rather its deficiency may provoke cancer initiation.

Menopausal hormone therapy and breast cancer risk in the NIH-AARP Diet and Health Study Cohort

BACKGROUND

Results from the Women's Health Initiative trial raise new questions regarding the effects of estrogen therapy (ET) and estrogen plus progestin therapy (EPT) on breast cancer risk.

METHODS

We analyzed data from 126,638 females, ages 50 to 71 years at baseline, who completed two questionnaires (1995--1996 and 1996--1997) as part of the NIH-AARP Diet and Health Cohort Study and in whom 3,657 incident breast cancers were identified through June 30, 2002. Hormone-associated relative risks (RR) and 95% confidence intervals (CI) of breast cancer were estimated via multivariable regression models.

RESULTS

Among thin women (body mass index < 25 kg/m2), ET use was associated with a significant 60% excess risk after 10 years of use. EPT was associated with a significantly increased risk among women with intact uteri, with the highest risk among current, long-term (> or = 10 years) users (RR, 2.44; 95% CI, 2.13-2.79). These risks were slightly higher when progestins were prescribed continuously than sequentially (< 15 days/mo; respective RRs of 2.76 versus 2.01). EPT associations were strongest in thin women, but elevated risks persisted among heavy women. EPT use was strongly related to estrogen receptor (ER)-positive tumors, requiring consideration of this variable when assessing relationships according to other clinical features. For instance, ER- ductal tumors were unaffected by EPT use, but all histologic subgroups of ER+ tumors were increased, especially low-grade and mixed ductal-lobular tumors.

CONCLUSIONS

Both ET and EPT were associated with breast cancer risks with the magnitude of increase varying according to body mass and clinical characteristics of the tumors.

Use of different postmenopausal hormone therapies and risk of histology- and hormone receptor-defined invasive breast cancer

PURPOSE

We previously found that the risk of invasive breast cancer varied according to the progestagen component of combined postmenopausal hormone therapy (CHT): progesterone, dydrogesterone, or other progestagens. We conducted the present study to assess how these CHTs were associated with histology- and hormone receptor-defined breast cancer.

PATIENTS AND METHODS

We used data from the French E3N cohort study, with 80,391 postmenopausal women followed for a mean duration of 8.1 years; 2,265 histologically confirmed invasive breast cancers were identified through biennial self-administered questionnaires completed from 1990 to 2002. The relative risks (RRs) were estimated using Cox proportional hazards models.

RESULTS

Compared with postmenopausal hormone therapy (HT) never-use, ever-use of estrogen+progesterone was not significantly associated with the risk of any breast cancer subtype, but increasing duration of estrogen+progesterone was associated with increasing risks of lobular (P = .06) and estrogen receptor-positive/progesterone receptor-negative (ER+/PR-; P = .02). Estrogen+dydrogesterone was associated with a significant increase in risk of lobular carcinoma (RR, 1.7; 95% CI, 1.1 to 2.6). Estrogen+other progestagens was associated with significant increases in risk of ductal and lobular carcinomas (RR, 1.6; 95% CI, 1.3 to 1.8; and 2.0; 95% CI, 1.5 to 2.7, respectively), of ER+/PR+ and ER+/PR- carcinomas (RR, 1.8; 95% CI, 1.5 to 2.1; and 2.6; 95% CI, 1.9 to 3.5, respectively), but not of ER-/PR+ or ER-/PR- carcinomas (RR, 1.0; 95% CI, 0.5 to 2.1; and 1.4; 95% CI, 0.9 to 2.0, respectively).

CONCLUSION

The increase in risk of breast cancer observed with the use of CHTs other than estrogen+progesterone and estrogen+dydrogesterone seems to apply preferentially to ER+ carcinomas, especially those ER+/PR-, and to affect both ductal and lobular carcinomas.

Relationship between menopausal hormone therapy and risk of ductal, lobular, and ductal-lobular breast carcinomas

Combined estrogen and progestin hormone therapy (CHT) increases breast cancer risk, but this risk varies by breast cancer type. Several studies indicate that CHT is more strongly related to lobular carcinoma risk than to ductal carcinoma risk, but these studies have been limited in their assessments of recency and duration of use, and none included a centralized pathology review. We conducted a population-based case-control study consisting of 324 lobular, 196 ductal-lobular, and 524 ductal cases diagnosed from 2000 to 2004 and 469 controls ages 55 to 74 years old. Tissue specimens were centrally reviewed for 83% of cases. Associations between hormone use and breast cancer risk were evaluated using polytomous logistic regression. Current CHT users had 2.7-fold [95% confidence interval (95% CI), 1.7-4.2] and 3.3-fold (95% CI, 2.0-5.7) elevated risks of lobular and ductal-lobular carcinomas, respectively, regardless of tumor stage, size, or nodal status. Elevations in risk were observed only among users of CHT for > or =3 years. Among ductal-lobular cases, CHT increased risk of tumors that were > or =50% lobular (odds ratio, 4.8; 95% CI, 2.1-11.1) but not tumors that were <50% lobular (odds ratio, 1.9; 95% CI, 0.9-4.1). Current CHT users for > or =3 years have a substantially increased risk of lobular carcinomas. Although lobular carcinomas are less common than ductal carcinomas ( approximately 16% versus 70% of all invasive breast cancers in the United States), this duration is shorter than the 5 years of use widely cited to be needed to confer an increased risk of breast cancer overall. Further studies focusing on the etiology of lobular carcinomas are needed.

Impact of hormone replacement therapy on the histologic subtype of breast cancer

OBJECTIVE

Postmenopausal hormone replacement therapy (HRT) is associated with an increase in breast cancer risk, which correlates to the duration of HRT use. We wanted to investigate a possible association between HRT use and the risk of a histologic subtype of breast cancer.

PATIENTS AND METHODS

From 1995 until 2004, 497 cases of primary ductal, lobular or ductulolobular breast cancer in postmenopausal women were diagnosed at the Department of Gynecology and Obstetrics, University Hospital Basel, Switzerland. The data was derived from patient's records. HRT ever use was defined as HRT use for > or =6 months.

RESULTS

Of the 99 cases of lobular cancer 72.7% were invasive lobular cancers, 21.2% were invasive ductulolobular cancers and 6.1% were lobular cancers in situ. Of the 398 cases of ductal cancer, 90.5% were invasive ductal cancers and 9.5% were ductal cancers in situ. Totally 144 women were HRT ever users, and 341 women were HRT never users. HRT status could not be defined in 12 women. HRT ever use was associated with an increased risk for lobular cancer (OR 1.67; 95% CI 1.02-2.73). Also, menopause due to bilateral oophorectomy was associated with an increased risk for lobular cancer (OR 2.42; 95% CI 1.06-5.54).

CONCLUSIONS

There is evidence that HRT as well as menopause due to bilateral oophorectomy may be associated with an increased risk for lobular cancer. This association is of major clinical relevance, since lobular breast cancer is more difficult to diagnose clinically and radiologically than ductal breast cancer.

Decline in breast cancer incidence due to removal of promoter: combination estrogen plus progestin

Combination estrogen plus progestin causes breast cancer. In light of this causal relation, the rapid decline in breast cancer incidence noted in 2003, following an earlier and slower reduction in incidence from 1999, raises important issues regarding the proportion of this decline that may be due to a reduction in the use of combination therapy by postmenopausal women. The context of these national trends is reviewed and the strong link to the use of hormone therapy is discussed, after noting that screening cannot explain any substantial component of these trends. The rapid decrease in incidence, most evident among women aged 50 to 69 years and in estrogen receptor positive tumors, that parallels the decline in combination hormone use is consistent with a promoter effect for estrogen plus progestins.

Changes in breast cancer incidence rates in the United States by histologic subtype and race/ethnicity, 1995 to 2004

Breast cancer incidence rates rose throughout the 1980s and 1990s in the United States but have recently declined through 2004. Studies reporting this decline primarily attribute it to the sharp decline in menopausal hormone use following publication of the Women's Health Initiative trial results. However, they have not stratified rates by either histologic type or race/ethnicity, which could further inform contributors to these trends. Using data from 13 cancer registries that participate in the Surveillance, Epidemiology, and End Results program, we evaluated annual percent changes (APC) in breast cancer incidence rates from 1995 to 2004 by histologic type and race/ethnicity for intervals identified using joinpoint regression. Invasive ductal carcinoma and invasive lobular carcinoma incidence rates fell steadily from 1998 to 2004 [APC, -3.07% (95% confidence interval, -4.10 to -2.02) and APC, -3.18% (95% confidence interval, -5.18 to -1.03), respectively]. Declines in rates of breast cancer overall and invasive ductal carcinoma were primarily limited to women > or = 50 years of age and to non-Hispanic whites and Asian/Pacific Islanders, and declines in rates of invasive lobular carcinoma were primarily limited to non-Hispanic whites. The majority of these declines began around 1998 and all began before 2002 when the Women's Health Initiative trial results were published; thus, the abrupt decline in hormone therapy use starting in 2002 is unlikely to be primarily responsible for the recent decline in breast cancer rates. The declines observed thus far are likely attributable to saturation of screening, although further declines related to the widespread cessation of hormone use may follow.

The association between oral contraceptive use and lobular and ductal breast cancer in young women

Recent reports indicate that the incidence of lobular breast cancer is increasing at a faster rate than ductal breast cancer, which may be due to the differential effects of exogenous hormones by histology. To address this issue, we examined whether the relationship between oral contraceptive use and incident breast cancer differs between lobular and ductal subtypes in young women. A population-based sample of in situ and invasive breast cancer cases between ages 20 and 44 were recruited from Atlanta, GA; Seattle-Puget Sound, WA and central New Jersey. Controls were sampled from the same areas by random-digit dialing, and were frequency matched to the expected case age distribution. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using polytomous logistic regression. Among the 100 lobular cancers, 1,164 ductal cancers, and 1,501 controls, the odds ratios for oral contraceptive ever use were 1.10 (95% CI = 0.68-1.78) for lobular cancers and 1.21 (95% CI = 1.01-1.45) for ductal cancers, adjusted for study site, age at diagnosis, and pap screening history. Our results suggest that the magnitude of the association between ever use of oral contraceptives and breast cancer in young women does not vary strongly by histologic subtype. These results are similar to previous studies that report little difference in the effect of oral contraceptive use on breast cancer by histology.

Menopause: developing a rational treatment plan

In recent years, growing importance has been afforded to assisting women in coping with the menopausal transition. Menopause is a normal stage of development and a woman's attitude toward this transition embodies biological, psychological and social influences. An enlarging body of conflicting data concerning menopausal hormone therapy (MHT) demands reassessment of established paradigms of disease prevention and menopausal health. Currently, a woman's decision to participate in or abstain from menopausal HT is personal. It involves not only consideration of risk stratification of potential harm and benefit, but also involves her expectations and attitudes toward perceived physical and emotional changes associated with this change. Through the use of extensive patient history, quality-of-life questionnaires and powerful biological profiling, we may be able to develop a rational approach to menopausal HT that safely guides our patients through this transition.

Progestins and breast cancer

Progestins exert their progestational activity by binding to the progesterone receptor (form A, the most active and form B, the less active) and may also interact with other steroid receptors (androgen, glucocorticoid, mineralocorticoid, estrogen). They can have important effects in other tissues besides the endometrium, including the breast, liver, bone and brain. The biological responses of progestins cover a very large domain: lipids, carbohydrates, proteins, water and electrolyte regulation, hemostasis, fibrinolysis, and cardiovascular and immunological systems. At present, more than 200 progestin compounds have been synthesized, but the biological response could be different from one to another depending on their structure, metabolism, receptor affinity, experimental conditions, target tissue or cell line, as well as the biological response considered. There is substantial evidence that mammary cancer tissue contains all the enzymes responsible for the local biosynthesis of estradiol (E(2)) from circulating precursors. Two principal pathways are implicated in the final steps of E(2) formation in breast cancer tissue: the 'aromatase pathway', which transforms androgens into estrogens, and the 'sulfatase pathway', which converts estrone sulfate (E(1)S) into estrone (E(1)) via estrone sulfatase. The final step is the conversion of weak E(1) to the potent biologically active E(2) via reductive 17beta-hydroxysteroid dehydrogenase type 1 activity. It is also well established that steroid sulfotransferases, which convert estrogens into their sulfates, are present in breast cancer tissues. It has been demonstrated that various progestins (e.g. nomegestrol acetate, medrogestone, promegestone) as well as tibolone and their metabolites can block the enzymes involved in E(2) bioformation (sulfatase, 17beta-hydroxysteroid dehydrogenase) in breast cancer cells. These substances can also stimulate the sulfotransferase activity which converts estrogens into the biologically inactive sulfates. The action of progestins in breast cancer is very controversial; some studies indicate an increase in breast cancer incidence, others show no difference and still others a significant decrease. Progestin action can also be a function of combination with other molecules (e.g. estrogens). In order to clarify and better understand the response of progestins in breast cancer (incidence, mortality), as well as in hormone replacement therapy or endocrine dysfunction, new clinical trials are needed studying other progestins as a function of the dose and period of treatment.

Recent trends in breast cancer incidence among 6 Asian groups in the Greater Bay Area of Northern California

Asians and Pacific Islanders are typically aggregated in United States (US) cancer statistics even though the few studies that have considered subgroups separately have found marked differences in cancer incidence. The objective of this study was to evaluate trends in breast cancer incidence rates separately for US Chinese, Japanese, Filipino, Korean, South Asian and Vietnamese women overall and by age at diagnosis, histologic subtype and stage at diagnosis. Age-adjusted incidence rates and annual percent changes (APC) of new, primary breast cancer diagnosed in the Greater Bay Area Cancer Registry of Northern California (1990-2002) were calculated using SEER*Stat. In women under 50 years of age, annual incidence rates decreased for Japanese (APC = -4.1, p = 0.02) and Filipinas (APC = -1.9, p = 0.11), and increased or fluctuated in other subgroups over the study period. In women 50 years or older, rates of invasive breast cancer increased for most subgroups, except Filipinas (APC = -1.3, p = 0.32), and in Japanese until 1998-2000. Rates of breast cancer in situ increased in most subgroups from 1990 to 2002, as did rates of lobular breast cancer for Chinese (APC = +7.46, p < 0.01) women. In Japanese women, rates of lobular breast cancer were highest in 1995-1997 and decreased thereafter. Our data support the notion that the prevalence of established risk factors influence breast cancer incidence, as breast cancer rates increased for more recently immigrated groups and decreased among more established groups, and may suggest leads into other avenues of research, such as genetic differences, that may explain differences in incidence rates among Asian subgroups.

Primary systemic chemotherapy of invasive lobular carcinoma of the breast

Invasive lobular carcinoma is the second most frequent histological type of breast cancer and its incidence is increasing. It has unique clinical, biological, and molecular features. Invasive lobular carcinoma is almost invariably positive for the oestrogen receptor and, when compared with invasive ductal carcinoma, it is typically of a lower grade. Even though invasive lobular carcinoma represents a distinct clinical entity, the same criteria used for invasive ductal carcinoma are currently applied to establish the need for primary or adjuvant systemic chemotherapy. We reviewed randomised trials of neoadjuvant and adjuvant chemotherapy and noted that insufficient evidence is available to support or withhold use of chemotherapy in patients with invasive lobular carcinoma. Thus, the benefit from systemic chemotherapy for individuals with this form of breast disease is unclear. Invasive lobular carcinoma deserves to be investigated separately in prospective clinical trials to define the best treatment and prevention strategies.

Hormone replacement therapy, mammography screening and changing age-specific incidence rates of breast cancer: an ecological study comparing two European populations

BACKGROUND

In 2003, for the first time, US breast cancer incidence rates have fallen. Experts argue whether this is due to the reduced uptake of screening mammography or to lower use of Hormone Replacement Therapy (HRT). This study aims to disentangle the respective impact of screening and HRT on age-incidence rates and histology of breast cancer, by comparing two populations with comparably high levels of screening mammography, but with different prevalence of HRT.

METHODS

We included all invasive breast cancers recorded at the Geneva cancer registry (n = 4,909) and the Netherlands Cancer Registry (n = 152,428) between 1989-2003. We compared age-specific incidence rates and trends in histological subtyping between the two populations.

RESULTS

Between 1989-1991, incidence rates increased with age in both populations. In 2001-2003, women aged 60-64 years showed highest incidence rates in Geneva, while in the Netherlands incidence rates continued to increase with age. The annual increase in ductal cancer incidence was similar in the Netherlands (2.3%) and Geneva (2.5%), but the annual increase in lobular cancer was sharper in Geneva (10%) than in the Netherlands (5%).

CONCLUSION

The sharp differences in age distribution and histological subtyping of breast cancer between two European populations are not attributable to screening, since both populations have a high uptake of mammography screening. Since the prevalence of HRT use is very high in Geneva and rather low in the Netherlands, HRT may explain these discrepancies. However, other etiological factors and differences in histological assessment may also have played a role.

Identification of membrane progestin receptors in human breast cancer cell lines and biopsies and their potential involvement in breast cancer

Novel membrane progestin receptors (mPRs) coupled to G proteins recently identified in several species, including humans, are potential intermediaries in rapid, nongenomic progestin actions observed in a wide variety of tissues. Here we demonstrate mPR mRNA and protein expression and specific membrane-associated progestin binding in MCF-7 and SK-BR-3 human breast cancer cells. Interestingly, human mPRalpha mRNA expression was higher in breast tumor biopsies than in normal tissue from the same breast. Recent studies indicate intracellular signaling pathways initiated by the mPRs are broadly similar to those induced during breast cancer growth and development. Taken together these results suggest a potential involvement of mPRs during the development or progression of breast cancer.