Breast carcinoma developing in patients on hormone replacement therapy: a histological and immunohistological study

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.

Obesity and menopausal status impact the features and molecular phenotype of invasive lobular breast cancer

Purpose

We investigated the relationship between obesity, menopausal status, and invasive lobular carcinoma (ILC), the second most common histological subtype of breast cancer. Specifically, we evaluated the association between body mass index (BMI), metabolic syndrome, the 21-gene Oncotype Recurrence Score (Oncotype RS), and pathological features in patients with hormone receptor (HR)-positive, human epidermal growth factor receptor-2-negative ILC.

Methods

The study cohort included 491 patients from a prospectively maintained institutional database consisting of patients with stage I-III, HR-positive ILC who underwent surgical treatment between 1996 and 2019.

Results

Contrary to our expectations, we found that lower BMI was significantly associated with having higher Oncotype RS (18.9% versus 4.8%, p = 0.028) in post-menopausal patients, but was not related to tumor characteristics in pre-menopausal patients. Multivariate network analyses suggested a strong relationship between post-menopausal status itself and tumor characteristics, with lesser influence of BMI.

Conclusion

These findings provide further insight into the recently appreciated heterogeneity within ILC and support the need for further investigation into the drivers of this disease and tailored treatment strategies.

Family history influences the tumor characteristics and prognosis of breast cancers developing during postmenopausal hormone therapy

Long term use of postmenopausal hormone therapy (HT) has been reported to increase breast cancer risk. On the other hand, observational studies suggest that breast cancers diagnosed during HT may have a more favorable prognosis. While family history is a risk factor for breast cancer, and genetic factors also influence prognosis, the role of family history in combination with HT use has been little studied. We investigated the relationship between HT, family history, and prognosis in 584 (267 exposed) familial and 952 (460 exposed) non-familial breast cancer cases, using three survival end points: death from breast cancer (BCS), distant disease free survival (DDFS), and local recurrence free survival (LRFS). Among non-familial cases, HT was associated with better BCS (HR 0.63, 95% CI 0.41-0.94; p = 0.025), and DDFS (HR 0.58, 95% CI 0.40-0.85; p = 0.005), with a consistent but not statistically significant effect in LRFS. This effect was not seen in familial cases (HR > 1.0), and family history was found to interact with HT in BCS (p_{(interaction)} = 0.0067) (BC-death) and DDFS (p_{(interaction)} = 0.0070). There was phenotypic heterogeneity between HT-associated tumors in familial and non-familial cases, particularly on estrogen receptor (ER) status, although the interaction between HT and family history appears to be at least partially independent of these markers (p = 0.0370 after adjustment for standard prognostic factors). If confirmed by further studies, our results suggest that family history should be taken into consideration in clinical counseling before beginning a HT regimen.

Breast cancer susceptibility risk associations and heterogeneity by E-cadherin tumor tissue expression

E-cadherin is involved in cell-cell adhesion and epithelial-to-mesenchymal transitions. In cancers, loss or inactivation of E-cadherin is associated with epithelial cell proliferation and invasion. Here, we sought to determine, if risk associations for 18 breast cancer susceptibility single nucleotide polymorphisms (SNPs) differed by E-cadherin tumor tissue expression in the Polish Breast Cancer Study (PBCS), using data on 1,347 invasive breast cancer cases and 2,366 controls. E-cadherin expression (low/high) was assessed using immunohistochemical staining of tumor tissue microarrays. Replication data on 2,006 cases and 6,714 controls from the Study of Epidemiology and Risk Factors in Cancer Heredity was used to follow-up promising findings from PBCS. In PBCS, we found the rs11249433 SNP at the 1p11.2 locus to be more strongly associated with risk of E-cadherin low tumors (OR = 1.30, 95 % CI = 1.08-1.56) than with E-cadherin high tumors [OR = 1.06, 95 % CI = 0.95-1.18; case-only p-heterogeneity (p-het) = 0.05]. Findings in PBCS for rs11249433 were replicated in SEARCH. Combined analyses of the two datasets for SNP rs11249433 revealed significant heterogeneity by E-cadherin expression (combined case-only p-het = 0.004). Further, among carriers of rs11249433, the highest risk was seen for E-cadherin low tumors that were ER-positive and of lobular histology. Our results in two independent data sets suggest that rs11249433, which is located between the NOTCH2 and FCGR1B genes within the 1p11.2 locus, is more strongly associated with risk of breast tumors with low or absent E-cadherin expression, and suggest that evaluation of E-cadherin tumor tissue expression may be useful in clarifying breast cancer risk factor associations.

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.

Expression of estrogen receptor alpha and beta in breast cancers of pre- and post-menopausal women

Expression of estrogen receptors (ER) is clinically relevant in designing therapeutic strategies. The relative importance of the two types of estrogen receptors (ER-alpha and ER-beta) in human breast cancers in pre- and post-menopausal women has not been properly defined. To determine the possible association between the expression of estrogen receptor and serum estradiol levels in pre- and post-menopausal women with breast cancer. 44 patients with invasive ductal carcinoma of the breast were studied and a breast tissue biopsy was taken. ER-alpha and ER-beta were detected by immunocytochemistry. Serum levels of estradiol and estrone were measured by radioimmunoassay and FSH was measured using IRMA. We studied 21 pre- and 23 post-menopausal women with breast carcinoma. Examining the number of cases with tumors positive for ER, we found no differences in the frequency of ER-alpha between pre- and post-menopausal women, but ER-beta decreased marginally after menopause (p < 0.051). In cases with tumors positive for ER, the proportion of cells positive for ER-alpha was similar post-menopausally (53.95%) and pre-menopausally (57.21%), but for ER-beta the number of positive cells decreased significantly after menopause (p < 0.051). In pre-menopausal women there was a correlation between serum estradiol levels and ER-beta; in post-menopausal women there was a correlation between serum FSH levels and ER-alpha. These results indicate that estradiol levels in women with mammary carcinoma are related to ER-beta expression in the breast tumor tissue.

Hormone therapy and breast cancer: what factors modify the association?

OBJECTIVE

To determine factors that may modify the association between hormone therapy (HT) and breast cancer risk.

DESIGN

Prospective cohort study (the Melbourne Collaborative Cohort Study) of 24,479 women aged 40 to 69 years. History of HT use was collected at baseline and 4 years later by questionnaire. By June 2002, 336 cases of breast cancer were diagnosed among 13,444 women postmenopausal at baseline. Association of breast cancer risk with history of HT use was analyzed using proportional hazards models.

RESULTS

The hazard ratio (HR) for recent HT use (current or stopped within the last year) was elevated (HR 1.51; 95% CI, 1.16-1.98) but was not significantly increased for past HT users (HR 1.19; 95% CI, 0.86-1.64). Recent HT use was associated with better differentiated tumors but was not more likely to be associated with estrogen receptor-positive / progesterone receptor-positive tumors. There was little evidence of interactions between recent HT use and body mass index, alcohol intake, parity, and smoking, although the HR for recent HT use in categories of alcohol consumption was greatest in women consuming the most alcohol (HR 2.37; 95% CI, 1.45-3.88 for those consuming > or = 10 g/d versus HR 1.33; 95% CI, 0.85-2.08 for nondrinkers, P interaction = 0.32).

CONCLUSIONS

The risk of breast cancer for recent users of HT in this Australian population is increased by approximately 50%. Our results suggest that any potential modifying effect of the association between HT and breast cancer risk by factors such as alcohol intake and body mass index is likely to be modest.

Breast tumours following combined hormone replacement therapy express favourable prognostic factors

The aim of the present study was to evaluate the association between different types of hormone replacement therapy (HRT) and risk of specific breast cancer subgroups. A population-based prospective cohort study including 12,583 peri- or postmenopausal women were followed using record-linkage with national cancer registries. During an average follow-up of 4.5 years, 332 cases of invasive breast cancer were diagnosed. Tumour samples were available from 283 cases. These tumours were re-evaluated according to histological type, grade, and mitotic index. Evaluation of tumours included estrogen and progesterone receptor status (ERalpha, ERbeta and PgR), as well as expression of Ki67, HER2, cyclin D1 and p27. The incidence of breast cancer in current users of combined HRT (CHRT) was significantly higher than in non-users. The difference corresponded to an adjusted relative risk (95% confidence interval) of 3.01 (2.35-3.84) as obtained using a Cox's proportional hazards analysis. CHRT was associated with lobular tumours (3.48:1.99-6.10), grade 1 tumours (4.46:2.79-7.13) and tumours with a low mitotic index (4.35:2.99-6.34). CHRT was not related to any specific subgroup in terms of ERalpha-, ERbeta- or PgR-expression. CHRT was associated with low proliferating tumours, defined by the Ki67 index (3.58:2.60-4.93), HER2 amplified tumours (4.40:1.93-10.06), low expression of the oncogene cyclin D1 (3.14:2.32-4.23) and high expression of the tumour suppressor gene p27 (3.47:2.40-5.01). Use of estrogen-alone HRT (ERT) was not associated with any statistically significant risk of breast cancer. We conclude that the use of CHRT is associated with an increased incidence of breast tumours with comparatively favourable prognostic factors.

Hormone-replacement therapy influences gene expression profiles and is associated with breast-cancer prognosis: a cohort study

BACKGROUND

Postmenopausal hormone-replacement therapy (HRT) increases breast-cancer risk. The influence of HRT on the biology of the primary tumor, however, is not well understood.

METHODS

We obtained breast-cancer gene expression profiles using Affymetrix human genome U133A arrays. We examined the relationship between HRT-regulated gene profiles, tumor characteristics, and recurrence-free survival in 72 postmenopausal women.

RESULTS

HRT use in patients with estrogen receptor (ER) protein positive tumors (n = 72) was associated with an altered regulation of 276 genes. Expression profiles based on these genes clustered ER-positive tumors into two molecular subclasses, one of which was associated with HRT use and had significantly better recurrence free survival despite lower ER levels. A comparison with external data suggested that gene regulation in tumors associated with HRT was negatively correlated with gene regulation induced by short-term estrogen exposure, but positively correlated with the effect of tamoxifen.

CONCLUSION

Our findings suggest that post-menopausal HRT use is associated with a distinct gene expression profile related to better recurrence-free survival and lower ER protein levels. Tentatively, HRT-associated gene expression in tumors resembles the effect of tamoxifen exposure on MCF-7 cells.

The influence of hormone replacement therapy on the pathology of breast cancer

AIM OF THE STUDY

To assess whether the pathological characteristics of breast carcinomas arising in post-menopausal women who ever used hormonal replacement therapy (HRT) differ from those of post-menopausal patients who never used HRT.

MATERIALS AND METHODS

Six hundred and forty three consecutive breast cancer patients were entered in a case control-study. Cases were represented by 111 breast cancer patients who had used or were using HRT at the time of diagnosis, while the remaining 532 patients who never used HRT were chosen as controls.

RESULTS

Tumour diameter was smaller in HRT users (17.6 vs 22.1 mm; p=0.002) and tumours of lobular histology were almost twice more frequent among HRT users as in 'never users' (21 vs 12%; p=0.01). No differences were found in grading, hormonal receptor status and axillary nodal status. The expression of c-erb B-2, p53, Ki67 and PS2 measured by immunohistochemistry was similar in the two groups.

CONCLUSIONS

Our findings suggest that HRT use may modify the pathological presentation of breast cancer. Further studies are indicated, while other clinical-pathological characteristics did not differ according to HRT use.

Use of hormone replacement therapy (HRT) and survival following breast cancer diagnosis

Although hormone replacement therapy (HRT) use has been associated with breast cancers that have better prognostic features, it is not clear whether this leads to improved survival. We studied a cohort of 4022 postmenopausal women diagnosed with breast cancer between 1993 and 2000, who attended a mammographic screening program, among whom 312 deaths subsequently occurred. Proportional hazards models were used to examine survival from breast cancer and all-causes among HRT users and non-users. The multivariate hazard ratio for HRT use was 0.64 (95% CI: 0.41-1.00) for breast cancer deaths and 0.69 (95% CI: 0.49-0.96) for all-cause mortality. This was attenuated by grade (HR 0.71; 95% CI: 0.45-1.10). HRT use at diagnosis was associated with modestly improved survival from breast cancer that appeared in part to be explained by the influence of HRT on tumour grade, although we cannot exclude the possibility of confounding by factors associated with the choice to use HRT.

Postmenopausal hormone therapy and the risk of breast cancer

Reports from the Women's Health Initiative (WHI) and the Million Women Study have indicated that postmenopausal hormone therapy increases the risk of breast cancer. At this point in time, it is not certain whether these data reflect a small increase in risk or an impact of hormone therapy on pre-existing tumors. The purpose of this review is to provide an analysis of the epidemiologic data that can help the clinician inform patients and assist patients in their decision-making.

Postmenopausal hormone therapy and breast cancer: a clinician's message for patients

The Women's Health Initiative agrees with some but not all case-control and cohort studies that current use of postmenopausal estrogen-progestin therapy is associated with a small increase in the risk of breast cancer. It is not known whether this is because of new tumor growth or an effect of hormonal therapy on preexisting tumors. Many studies indicate that women who develop breast cancer while using postmenopausal hormone therapy have a reduced risk of dying from breast cancer; this is consistent with an effect on preexisting tumors so that tumors appear at a less virulent and aggressive stage.

Comparison of Age-Specific Incidence Rate Patterns for Different Histopathologic Types of Breast Carcinoma

Objective: The age-specific incidence rate curve for breast carcinoma overall increases rapidly until age 50 years, and then continues to increase at a slower rate for older women. In this analysis, our objective was to compare age-specific incidence rate patterns for different morphologic types of breast carcinoma. Materials and methods: We analyzed age-specific incidence rate curves by histopathologic subclassification using records from 11 standard National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registries, diagnosed during the years 1992 to 1999. Data were examined by age &lt;50 and ≥50 years to simulate menopause. Results: Age-specific incidence rate curves showed three dominant patterns: (1) Rates for infiltrating duct carcinoma of no special type (duct NST), tubular, and lobular carcinomas increased rapidly until age 50 years then rose more slowly. (2) Rates for medullary and inflammatory breast carcinomas increased rapidly until age 50 years then failed to increase. (3) Rates for papillary and mucinous carcinomas increased steadily at all ages. Rate patterns varied by estrogen receptor expression but were unaffected by SEER registry, race, nodal status, or grade. Conclusion: Age-specific incidence rates for breast carcinomas differed by histopathologic type. Rates that failed to increase after 50 years suggested that menopause had greater impact on medullary and inflammatory carcinomas than on duct NST, tubular, and lobular carcinomas. Menopause did not seem to have any effect on papillary or mucinous carcinomas as evidenced by steadily rising rates at all ages. Future etiologic and/or prevention studies should consider the impact of age-specific risk factors and/or exposures on different histopathologic types of breast carcinomas.

Duration of hormone replacement therapy, breast tumour size and grade in a screening programme

One of the primary adverse effects of long-term use of hormone replacement therapy (HRT) is a modest increase in the risk of breast cancer. Breast tumours that develop in women using HRT have been shown to have prognostically favourable histological features but it is unclear if this is the case for both short- and long-term use.

METHODS

We evaluated the association between HRT use with tumour size and histologic grade in a cohort of women aged over 55 years (n = 2200) diagnosed with invasive breast cancer at subsequent screen in BreastScreen Victoria (BSV), Australia between 1993 and 2000. BSV biennially screens women aged over 40 years with the target age group 50-69 years. Multiple linear regression was used to examine predictors of log-transformed tumour size and multinomial logistic regression was used to evaluate associations of HRT with tumour grade.

RESULTS

Short-term users of HRT (< or = 5 years), were approximately 50% less likely to develop poorly-differentiated breast tumours OR 0.48 95% CI (0.28-0.82) or node-positive tumours OR 0.57 95% CI (0.35-0.94) than non-users. Long-term users of HRT (> 5 years) were also less likely to develop poorly-differentiated tumours OR 0.36 95% CI (0.24-0.56) but were not more likely to be node-positive than women not on HRT. Duration of HRT use was not significantly associated with tumour size.

CONCLUSION

HRT use, regardless of duration, was associated with breast tumours that were better differentiated and not significantly larger than women not on HRT, although only short-term use was associated with fewer node-positive tumours.

Prognostic Characteristics of Breast Cancer Among Postmenopausal Hormone Users in a Screened Population

Purpose: We determined the risk of breast cancer and tumor characteristics among current postmenopausal hormone therapy users compared with nonusers, by duration of use.

Methods: From January 1996 to December 2000, data were collected prospectively on 374,465 postmenopausal women aged 50 to 79 years who underwent screening mammography. We calculated the relative risk (RR) of breast cancer (invasive or ductal carcinoma-in-situ) and type of breast cancer within 12 months of postmenopausal therapy use among current hormone users with a uterus (proxy for estrogen and progestin use) and without a uterus (proxy for estrogen use), compared with nonusers.

Results: Compared with nonusers, women using estrogen and progestin for ≥ 5 years were at increased risk of breast tumors of stage 0 or I (RR, 1.51; 95% CI, 1.37 to 1.66), stage II or higher (RR, 1.46; 95% CI, 1.30 to 1.63), size ≤ 20 mm (RR, 1.59; 95% CI, 1.43 to 1.76), size greater than 20 mm (RR, 1.24; 95% CI, 1.09 to 1.42), grade 1 or 2 (RR, 1.60; 95% CI, 1.44 to 1.77), grade 3 or 4 (RR, 1.54; 95% CI, 1.37 to 1.73), and estrogen receptor-positive (RR, 1.72; 95% CI, 1.55 to 1.90). Estrogen-only users were slightly more likely to have estrogen receptor-positive breast cancer compared with nonusers (RR, 1.14; 95% CI, 1.06 to 1.23).

Conclusion: Use of estrogen and progestin postmenopausal hormone therapy for five years or more increased the likelihood of developing breast cancer, including both tumors with favorable prognostic features and tumors with unfavorable prognostic features.

Important increase of invasive lobular breast cancer incidence in Geneva, Switzerland

A recent paper from the United States reported a sharp and unexplained increase in invasive lobular breast cancer incidence since 1977 (Li et al., Cancer 2000;88:2561-9). We investigated if this trend was also present in Geneva, Switzerland, where breast cancer incidence is one of the highest in Europe. We analyzed trends in breast cancer incidence according to histologic subtype, age and stage, to clarify the pattern. Our population-based study includes all histologically confirmed invasive breast carcinomas (n = 6,247) recorded between 1976 and 1999 at the Geneva Cancer Registry. Breast histology was classified as ductal carcinoma, lobular carcinoma and other. Incidence trends were studied by log-linear regression analyses. Models including effects of age, period and birth cohorts were used to describe rising incidence trends. The incidence of ductal carcinoma increased 1.2% per year (p(trend) < 0.001) from 85.2 to 110.1/100,000. This increase concerned women aged 50-69 years and early-stage tumors. Lobular cancer incidence increased disproportionately (14.4% per year, p(trend) < 0.01) and rose from 2.9 to 20.5/100,000. This increase affected all age categories and both localized and advanced stages. In addition, a strong age-cohort effect was present (p < 0.05), and women aged 50-59 years born after 1944 experienced the most marked increase. Our study shows a disproportionate increase of lobular breast cancer incidence compared to ductal cancer incidence. Contrary to ductal cancer, trends for lobular cancer are unlikely to be explained by increased use of screening mammography. Other explanations must be researched, in particular the role played by hormone replacement therapy.

Progestins and breast cancer

The relationship between the use of menopausal hormone therapy (ERT, unopposed estrogen therapy; HRT, combined estrogen and progestin therapy) and the development of breast cancer remains controversial. Mechanistic studies examining progestins in human breast cancer cell lines have demonstrated a biphasic cellular response to progesterone; initial exposure to hormone results in a proliferative burst with sustained exposure resulting in growth inhibition. To date, there is no definitive evidence that progestins act in the pathogenesis of breast cancer. Epidemiologic studies have produced inconsistent results, and data from randomized, placebo-controlled trials are limited. Although recent results from the continuous combined therapy arm of the Women's Health Initiative trial showed a small increase in the risk of invasive breast cancer in women on therapy for 5 years or more, a clear consensus regarding the relationship between HRT and breast cancer risk cannot yet be drawn from existing data. Studies have consistently documented that HRT use is associated with improved mortality and survival rates for women with breast cancer. Large-scale, randomized studies on different progestin regimens are needed to critically assess the effect of progestin on breast cancer.

Hormone replacement therapy containing progestins and given continuously increases breast carcinoma risk in Sweden

BACKGROUND

The authors previously reported an increased risk of breast carcinoma with longer duration of hormone replacement therapy (HRT) use. It is unclear if different types of HRT confer different risks.

METHODS

In this study, a population-based cohort of 29,508 women were interviewed during 1990-1992 to determine whether there are any differences in breast carcinoma risk according to different types and duration of HRT use.

RESULTS

At the end of the follow-up period in December 2001, the cohort constituted 298,649 person-years. Slightly more breast carcinoma cases were seen (n = 556) than expected (n = 508.37; standardized morbidity ratio =1.09, 95% confidence interval [CI] = 1.00-1.19). Approximately 3663 women had ever used HRT. In Cox regression models, time to breast carcinoma in relation to duration and type of HRT use was analyzed, adjusting for age at menarche, age at first full-term pregnancy, parity, age at menopause, family history of breast carcinoma, and age at interview. In women with a natural menopause, a significantly higher risk was observed for longer duration of combined continuous HRT use compared with never users (hazard ratio [HR] = 4.60, 95% CI = 2.39-8.84). Nonsignificant elevated risks also were observed for longer combined sequential (HR = 2.23, 95% CI = 0.90-5.56), gestagen only (HR = 3.74,9 5% CI = 0.94-14.97), and estriol use (HR = 1.89, 95% CI = 0.81-4.39). No increased risk was seen in women after 5 years of nonuse. When studying women who ever used only one type of HRT, even more elevated HRs for gestagen-containing preparations were seen. The highest risks were associated with the combined continuous and gestagen-only therapy in women with >/= 48 months of use. Use of estradiol without progestins did not increase breast carcinoma risk significantly. The authors estimated the cumulative risk of breast carcinoma in a 50-year-old woman with gestagen-containing therapies for >/= 48 months, with a follow-up of 10 years, to be 7% (95% CI = 5.4-11.4%) compared with 2% (95% CI = 1.6%-2.9%) for never-users of HRT.

CONCLUSIONS

Longer use of HRT containing progestins significantly elevates breast carcinoma risk whereas estradiol use does not. Continued use of progestins rendered the highest risks. The yearly risk of breast carcinoma for long-term users of progestins is of the magnitude of 50% the risk of a BRCA1 mutation carrier.

Breast cancer and post-menopausal hormone therapy

From the introduction of post-menopausal hormone replacement therapy (HRT) there has been great concern that HRT could possibly increase the risk of breast cancer. Prolonged exposure to endogenous oestrogens undeniably increases the risk of breast cancer. Questions that are important and until now only partly answered, are the following. Are oestrogens tumour promoters, as they induce mitosis, lead to proliferation and, therefore, accelerated growth of clinically occult pre-existing tumours? In addition to this, are they genotoxic mutagenic carcinogens, or could they initiate tumours by way of accumulation of incessant DNA-replication damage mechanism? Opinions vary as to the effect of the addition of a progestogen. There is a multitude of different progestogens which could bind with differing affinity to progesterone receptor PR-A or PR-B, and which have different physiological functions via differential gene regulation. The action of a progestogen on the oestrogen-induced cellular mitotic activity could be synergistic or antagonistic (by different pathways: oestrogen receptor downregulation, activating of metabolic pathways within the breast or stimulation of apoptosis)? Over 60 observational studies and two randomized trials provide evidence that the small but significant increase in risk appears with long-term current post-menopausal hormone use. The addition of a progestogen does not decrease the risk as seen with oestrogens alone and might increase the risk further. It is not clear whether there is a difference in risk with sequentially combined versus continuously combined HRT. Many questions nevertheless still remain. Is the risk increase limited to lean women only? What about risk-modifying factors such as alcohol use and a positive family history for breast cancer? Are tumours detected under HRT less aggressive, is there a better prognosis and is the mortality not increased while morbidity is? And is HRT contraindicated for women with a positive family history for breast cancer or in those women who have been treated for breast cancer? And finally, are there alternative options for these women?

Relation of regimens of combined hormone replacement therapy to lobular, ductal, and other histologic types of breast carcinoma

BACKGROUND

The incidence of invasive lobular carcinoma has been increasing among postmenopausal women in some parts of the United States. Part of this may be due to changes in classification over time. However, the use of combined (estrogen and progestin) hormone replacement therapy (CHRT) also has increased during the last decade and may account in part for the increase in invasive lobular breast carcinoma.

METHODS

A large, multicenter case-control study of Caucasian and African-American women who were diagnosed at age < 65 years with their first invasive breast tumor from July 1, 1994 through April 30, 1998 was conducted. In-person interviews were conducted with 1749 postmenopausal patients, and their responses were compared with the responses of 1953 postmenopausal control women identified through random-digit dialing who met the study criteria of being postmenopausal at the time of diagnosis. Polytomous logistic regression was used to calculate the odds ratio (OR) as an estimate of the relative risk and to compute the 95% confidence interval (95%CI) associated with the use of various regimens of hormone replacement therapy (HRT) among women diagnosed with ductal breast carcinoma, lobular (or mixed lobular and ductal) breast carcinoma, and a grouping of other histologic types of breast carcinoma.

RESULTS

Ever use of unopposed estrogen therapy (ERT) was not associated with an increase in the risk of any histologic type of breast carcinoma. The risk of invasive lobular breast carcinoma and the risk of breast carcinoma of the grouping of other histologies increased among women currently using CHRT (OR, 2.2; 95%CI, 1.4-3.3; and OR, 1.9; 95%CI, 1.0-3.4, respectively). The risk increase was greater for the mixed lobular-ductal type than for the pure lobular type of breast carcinoma, although the difference was not statistically significant. There was some indication that >or= 5 years of continuous CHRT (>or= 25 days per month of progestin) was associated with a higher risk of lobular breast carcinoma (OR, 2.5; 95%CI, 1.4-4.3) compared with sequential CHRT (< 25 days per month of progestin; OR, 1.5; 95%CI, 0.8-2.6). Current use of continuous CHRT was only moderately associated with risk of ductal breast carcinoma.

CONCLUSIONS

Postmenopausal women who take CHRT appear to be at an increased risk of lobular breast carcinoma. Data from this study suggest that neither ERT use nor CHRT substantially increase the risk of ductal breast carcinoma among women age < 65 years.

A population-based cohort study of HRT use and breast cancer in southern Sweden

The overall tumour incidence and breast cancer incidence related to hormone replacement therapy (HRT) were followed in a population-based cohort of 29 508 women, aged 25-65 when interviewed in 1990-92. By the end of the follow up in December 1999, there were 226 611 person-years of observation. A total of 1145 malignant tumours were recorded (expected 1166.6; SIR = 0.98, 95% CI 0.93-1.04). There was a small excess of breast cancer with 434 observed and 387.69 expected (SIR = 1.12, 95% CI 1.02-1.23). Among about 3 663 ever users of HRT, there was no increase in overall tumour incidence (SIR = 0.98, 95% CI 0.86-1.12) but a significant excess of breast cancer (SIR = 1.35, 95% CI 1.09-1.64) compared with never users (SIR = 1.07, 95% CI 0.96-1.19). Breast cancer increased with increasing duration of use and for 48-120 months use the SIR was 1.92 (95% CI 1.32-2.70). There was no significant interaction with family history of breast cancer although an independent additive effect was suggested between HRT use and family history. In a Cox regression model time to breast cancer in relation to duration of HRT use was analysed adjusting for age at menarche, age at menopause, age at first full term pregnancy, parity and age at diagnosis. A significantly higher risk was seen for longer duration of HRT use compared with never users. No increased risk is seen in women beyond 5 years after stopping HRT. There was no interaction between previous use of oral contraceptives and later HRT use.

Hormone Replacement Therapy After a Diagnosis of Breast Cancer in Relation to Recurrence and Mortality

BACKGROUND

Hormone replacement therapy (HRT) is typically avoided for women with a history of breast cancer because of concerns that estrogen will stimulate recurrence. In this study, we sought to evaluate the impact of HRT on recurrence and mortality after a diagnosis of breast cancer.

METHODS

Data were assembled from 2755 women aged 35-74 years who were diagnosed with incident invasive breast cancer while they were enrolled in a large health maintenance organization from 1977 through 1994. Pharmacy data identified 174 users of HRT after diagnosis. Each HRT user was matched to four randomly selected nonusers of HRT with similar age, disease stage, and year of diagnosis. Women in the analysis were recurrence free at HRT initiation or the equivalent time since diagnosis. Rates of recurrence and death through 1996 were calculated. Adjusted relative risks were estimated by use of the Cox regression model. All statistical tests were two-sided.

RESULTS

The rate of breast cancer recurrence was 17 per 1000 person-years in women who used HRT after diagnosis and 30 per 1000 person-years in nonusers (adjusted relative risk for users compared with nonusers = 0.50; 95% confidence interval [CI] = 0.30 to 0.85). Breast cancer mortality rates were five per 1000 person-years in HRT users and 15 per 1000 person-years in nonusers (adjusted relative risk = 0.34; 95% CI = 0.13 to 0.91). Total mortality rates were 16 per 1000 person-years in HRT users and 30 per 1000 person-years in nonusers (adjusted relative risk = 0.48; 95% CI = 0.29 to 0.78). The relatively low rates of recurrence and death were observed in women who used any type of HRT (oral only = 41% of HRT users; vaginal only = 43%; both oral and vaginal = 16%). No trend toward lower relative risks was observed with increased dose.

CONCLUSION

We observed lower risks of recurrence and mortality in women who used HRT after breast cancer diagnosis than in women who did not. Although residual confounding may exist, the results suggest that HRT after breast cancer has no adverse impact on recurrence and mortality.

Prognosis of breast cancers detected in women receiving hormone replacement therapy

OBJECTIVE

To determine the influence of hormone replacement therapy (HRT) on various prognostic factors of breast cancer (BC).

METHODS

A multi-centre case-control study was conducted, in which a comparison was made of the differences between various histological and biological clinical variables of BC detected in 121 women undergoing HRT at the time of diagnosis, and those cancers detected in 121 women of similar age not undergoing HRT. The variables were also analysed in function of the type of HRT and the length of time treated.

RESULTS

The tumours detected in patients receiving HRT presented significantly lower tumoural stages, a lower degree of affected axillary lymph node dissemination, and a greater percentage of well-differentiated tumours and positive estrogen receptors than those detected in women not under HRT. Most of these results due principally to those patients who were undergoing

CONCLUSIONS

Although the better prognosis of tumours detected in women receiving HRT may be due largely to their diagnosis at earlier stages, there is an increasing body of data leading one to think that these tumours present certain histological and biological characteristics that make such cancers less aggressive.

Solid low-grade in situ carcinoma of the breast: role of associated lesions and E-cadherin in differential diagnosis

Low-grade solid in situ carcinomas of the breast are difficult to classify. The authors investigated 12 cases of in situ carcinomas with equivocal features and correlated their histologic attributes with those of the associated invasive carcinomas as well as with E-cadherin expression in both in situ and invasive disease. E-cadherin-positive in situ lesions were invariably associated with invasive carcinomas of the ductal type. In situ carcinomas that were E-cadherin negative were associated with invasive carcinomas of the lobular type in five of six cases. In all cases, the invasive carcinomas showed the same pattern of E-cadherin reactivity as the in situ lesions. Sharply defined cellular membranes, necrosis, and occasional microacini were seen in both E-cadherin-positive and negative in situ carcinomas, whereas intracytoplasmic lumina and a noncohesive appearance were seen only in E-cadherin-negative lesions.

Effects of estrogens and hormone replacement therapy on breast cancer risk and on efficacy of breast cancer therapies

This review summarises preclinical and clinical data on effects of endogenous and exogenous estrogens on probability of breast cancer diagnosis, and on the course and efficacy of breast cancer therapies. The data indicate that higher endogenous estrogen exposure (e.g. pregnancy, early menarche and late menopause, estrogen levels in future breast cancer patients, obesity) or exogenous estrogens (oral contraceptives; hormone replacement therapies) may be associated with an increased probability of breast cancer diagnosis. However, there is little evidence that estrogens have deleterious effects on the course of breast cancer. Moreover, increased incidence of breast cancer diagnosis after prolonged hormone replacement therapy (HRT) use seems to be associated with clinically less advanced disease. In studies assessing both diagnosis and mortality, HRT is frequently associated with reduced mortality compared to never users. The interaction of progestagens and estrogens on the probability of breast cancer diagnosis is complex and dependent on type of progestagens and regimens employed. Efficacy of current treatment modalities for breast cancer (surgery, irradiation, adjuvant therapy or chemotherapy) is not negatively influenced by estrogens at concentrations considerably higher than those attained with current HRT preparations. Although it cannot be excluded that estrogens increase the probability of breast cancer diagnosis, available data fail to demonstrate that, once breast cancer has been diagnosed, estrogens worsen prognosis, accelerate the course of the disease, reduce survival or interfere with the management of breast cancer. It may therefore be concluded that the prevalent opinion that estrogens and estrogen treatment are deleterious for breast cancer, needs to be revisited. However, results of ongoing prospective, randomised clinical trials with different HRT regimens in healthy women or breast cancer survivors are needed to provide more definite conclusions about risks and benefits of HRT.

Breast cancer risk associated with polymorphism in CYP19 in Japanese women

Screening of the entire coding and major promoter regions of the CYP19 gene identified two novel polymorphisms at codon 39 (Trp to Arg) and codon 408 (silent) in addition to those reported previously at codon 264 (Arg to Cys) and intron 4 [tetranucleotide (TTTA) simple tandem repeat]. A case-control study was conducted in order to see whether or not these polymorphisms were associated with breast cancer risk in Japanese women. Homozygous and heterozygous carriers of the variant allele Arg at codon 39 showed a significantly decreased risk of breast cancer (OR=0.39, 95%C.I.=0. 17-0.89). On the other hand, homozygous carriers of the allele with 10 or more TTTA repeats at intron 4 showed a trend toward an increase (OR=1.80, 95%C.I.=0.97-3.36) in breast cancer risk. Other polymorphisms were found not to be associated with breast cancer risk. These results suggest that the CYP19 polymorphisms at exon 39 and intron 4 would be useful for selecting Japanese women at a high risk of breast cancer.

Estrogen receptor alpha in human breast cancer: occurrence and significance

Estrogens have long been recognized as being important for stimulating the growth of a large proportion of breast cancers. Now it is recognized that estrogen action is mediated by two receptors, and the presence of estrogen receptor alpha (ER alpha) correlates with better prognosis and the likelihood of response to hormonal therapy. Over half of all breast cancers overexpress ER alpha and around 70% of these respond to anti-estrogen (for example tamoxifen) therapy. In addition, the presence of elevated levels of ER alpha in benign breast epithelium appears to indicate an increased risk of breast cancer, suggesting a role for ER alpha in breast cancer initiation, as well as progression. However, a proportion of ER alpha-positive tumors does not respond to endocrine therapy and the majority of those that do respond eventually become resistant. Most resistant tumors remain ER alpha-positive and frequently respond to alternative endocrine treatment, indicative of a continued role for ER alpha in breast cancer cell proliferation. The problem of resistance has resulted in the search for and the development of diverse hormonal therapies designed to inhibit ER alpha action, while research on the mechanisms which underlie resistance has shed light on the cellular mechanisms, other than ligand binding, which control ER alpha function.

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

BACKGROUND

In the majority of studies, long term, recent use of hormone replacement therapy has been associated with an increased risk of breast carcinoma. However, little attention has been paid to the possibility that the magnitude of this association may vary according to the histologic type of breast carcinoma.

METHODS

In this population-based case-control study, interviews were conducted with 537 female residents of King County, Washington who were ages 50-64 years and who had been diagnosed with primary breast carcinoma between January 1, 1988 and June 30, 1990. Interviews with 492 randomly selected King County women without a history of breast carcinoma served as a basis for comparison. Analyses were performed separately for women with lobular and for those with ductal tumors.

RESULTS

Compared with nonusers of menopausal hormones, those who currently were using combined estrogen and progestin hormone replacement therapy (CHRT) and had done so for at least 6 months had an elevated risk of lobular breast carcinoma (odds ratio [OR] = 2.6; 95% confidence interval [95% CI], 1.1-5.8), but no change in their risk of ductal breast carcinoma was noted (OR = 0.7; 95% CI, 0.5-1. 1). The OR associated with current use of unopposed estrogen for at least 6 months was 1.5 (95% CI, 0.5-3.9) for lobular tumors and 0.7 (95% CI, 0.4-1.1) for ductal tumors. Similar results were found when cases of invasive tumor were analyzed separately.

CONCLUSIONS

The results of this study suggest that CHRT use increases the risk of lobular, but not ductal, breast carcinoma in middle-aged women.

Epidemiology, prevention, and early detection of breast cancer

Globally, breast cancer is the third most common form of cancer and the most common among women. The age-adjusted incidence rates of breast cancer are 176% higher in developed than in developing nations. Male breast cancer is rare, but important studies provided risk factor information for comparison with studies of female breast cancer. There has been considerable interest in a possible role of organochlorines and polychlorinated biphenyls in the etiology of breast cancer, but the results of several null studies indicate the likelihood of such associations is extremely remote, providing reassuring news for the public. Prophylactic mastectomy was observed to significantly reduce a woman's chances of developing breast cancer, but it does not lower the risk to zero. Tamoxifen was found to be an effective chemopreventive agent in the Breast Cancer Prevention Trial, but this result was not replicated in two randomized trials in Europe. Striking reductions in the risk for breast cancer were observed for raloxifene in a randomized, placebo-controlled trial that had been designed for the prevention of osteoporosis. A large-scale, randomized trial of tamoxifen-verus-raloxifene among women at increased risk for developing breast cancer is now underway.