Menopausal oestrogens and breast cancer risk: an expanded case-control study

Long-term postmenopausal estrogen therapy may be associated with increased risk of breast cancer: a cohort study

Reports of a role of postmenopausal estrogen replacement therapy in the development of breast cancer have been inconsistent. Although many epidemiologic studies have failed to show an association between short-term use of estrogen and breast cancer, there are indications that long-term use may present an increased risk. We undertook a long-term, retrospective cohort study of the incidence of breast cancer in women who had taken long-term estrogen (average 17.2 years), compared to women who had not taken estrogen. Subjects were 454 women born between 1900 and 1915, who were members of a large health maintenance organization in northern California. By the end of 1995, 26 (11.2%) of estrogen users developed breast cancer, as did 9 (4.1%) of the nonusers; the relative risk (RR) for estrogen use was 2.8 [95% confidence interval (95% CI) 1.3-5.9]. Adjustment for age and multiple breast cancer risk factors, including breast cancer surveillance, reduced the RR for estrogen to 2.0 (95% CI 0.9-4.5). We conclude that long-term estrogen use is associated with a substantially increased risk of breast cancer.

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

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

Hormone Replacement Therapy Acceptability to Nottingham Post-Menopausal Women with a Risk Factor for Osteoporosis

In Nottingham we have assessed the acceptability of oral hormone replacement therapy (HRT) for an at-risk group of post-menopausal women for osteoporosis. One hundred post-menopausal women between the ages of 50 and 70 years who had sustained a distal radial fracture were offered oral HRT. There was a 36% overall uptake of HRT with 9% of patients unable to take HRT because they had medical contraindications. The uptake in the 50–55 year age group was 54%. We conclude that in prospective studies of HRT for osteoporosis up to 50% of patients may not wish to take HRT and therefore study design should allow for this level of uptake.

Atypical epithelial hyperplasia of the breast: state of the art

INTRODUCTION

Atypical epithelial hyperplasia (AEH) of the breast is considered benign histological lesions with breast cancer risk. This review focuses on clinical signification and management of AEH that remains controversial.

AREAS COVERED

A review of published studies was performed using medline database. In this review, we fully describe the current evidence available. In particular, we describe 1) data from immunohistochemistry and molecular studies that suggest AEH is a precursor of breast cancer; 2) epidemiological studies demonstrate low rate of breast cancer in women with AEH; 3) surgical excision is necessary after diagnosis of AEH, such as lobular carcinoma in situ or atypical ductal hyperplasia, on core needle biopsy; 4) although current recommendations are evolving to fewer (if not no) excisions for flat epithelial with atypia and classic lobular neoplasia found on percutaneous biopsy (without radiologic indications for excision). Expert commentary: HEA management steel need prospective evidences, but recent retrospective data give some clue for less invasive management for some of HEA.

The challenges for cancer chemoprevention

The incidence of cancer is rising in parallel with an ageing populous thus increasing the strain on both treatment options and budgets for healthcare providers worldwide. New cancer therapies are being developed but at what cost? The new treatments are expensive and poor survival rates still exist for some cancers. What is needed now is to prevent or at least limit the disease occurring in the first place. This review evaluates the current situation and the progress in upcoming strategies as well as suggesting some areas for further research within the increasingly important field of cancer chemoprevention. The key principles of cancer chemoprevention are discussed and areas for improvement highlighted. Despite significant progress, chemoprevention has not been widely adopted. Cancer chemoprevention has many challenges to face but this only emphasises the size of the task. These hurdles include a lack of awareness of the benefits, a lack of interest and a lack of investment in taking prevention forward. Despite the huge potential importance of cancer prevention and clinical success stories such as the well-publicised HPV vaccine, the challenges remain significant. With cancer and its treatment being a global issue, the opportunities offered by chemoprevention must be re-evaluated and uptake of chemoprevention actively encouraged. If chemoprevention is to be adopted successfully, a holistic approach is required. This approach will involve multidisciplinary teams of healthcare providers and scientists with the big challenge particularly for medicinal chemists being to design and synthesise the ideal chemopreventative agent.

The safety of postmenopausal testosterone therapy

Testosterone is increasingly used as part of postmenopausal HRT regimens. Unfortunately, few androgenic preparations designed specifically for use in women have been approved by regulatory authorities. Ongoing concerns exist surrounding the potential long-term effects of testosterone therapy. Here, we review the most recent data on postmenopausal testosterone therapy, focusing particularly on the effects of testosterone on breast, endometrium and cardiovascular health.

Postmenopausal hormone therapy and ductal carcinoma in situ: a population-based case-control study

BACKGROUND AND AIM

The relationship between hormone therapy (HT) and invasive breast cancer has been extensively investigated, but the relationship between HT and in situ breast cancer has received relatively little attention. We examined the relationship between HT and ductal carcinoma in situ (DCIS) among postmenopausal women who participated in a population-based case-control study in Connecticut, USA.

METHODS

This analysis included 1179 post-menopausal women (603 controls and 576 cases), who comprised a subset of a population-based case-control study that included all incident cases of breast carcinoma in situ (BCIS) in Connecticut and frequency-matched controls by 5-year age intervals.

RESULTS

We found no association between DCIS and ever use of any HT (adjusted odds ratio (OR)=0.85, 95% confidence interval (CI): 0.65-1.11); of estrogen alone (adjusted OR=0.93; 95% CI: 0.68-1.29) or of estrogen and progesterone (adjusted OR=0.75; 95% CI: 0.52-1.08). There was also no association between DCIS and current use of these hormones. In addition, estimated risk of DCIS did not increase with duration of use of these preparations.

CONCLUSIONS

These results add to a small literature that remains inconclusive. To determine whether HT poses risk of in situ breast cancer, larger studies with greater power and precise control of important covariates (e.g., mammography screening) are needed, as are meta-analyses of available data.

Safety and tolerability of testosterone patch therapy for up to 4 years in surgically menopausal women receiving oral or transdermal oestrogen

Two clinical trials previously demonstrated the safety of 300 μg/day transdermal testosterone patch (TTP) treatment for up to 6 months in 1094 surgically menopausal women with hypoactive sexual desire disorder (HSDD). Adverse events (AE), clinical laboratory tests, vital signs, physical examinations and mammograms were evaluated in open-label extensions of these two trials for up to 4 years and are presented in this article. Nine hundred and sixty-seven patients received at least one application of the TTP resulting in 1092 patient-years of exposure. There was no increase over time in the rate of new occurrences or severity of AEs, serious AEs, or withdrawals due to AEs. The most common AEs associated with treatment were application site reactions and unwanted hair growth; however, most were mild and rarely resulted in study withdrawal. No clinically meaningful changes in serum chemistry, haematology, lipid profile, carbohydrate metabolism, renal and liver function or coagulation parameters were noted with up to 4 years of therapy. Consistent with age-appropriate expected rates, three cases of invasive breast cancer were observed. No important changes in the safety or tolerability profile of TTP were revealed with long-term use for up to 4 years in otherwise healthy oophorectomised women with HSDD on concomitant oestrogen.

Androgen deficiency and therapy in women

PURPOSE OF REVIEW

This review will provide a brief overview of androgen physiology, outline the conditions associated with androgen deficiency in women, and provide data on the potential benefits and risks of testosterone therapy.

RECENT FINDINGS

This review summarizes relevant data on treatment and reviews the findings regarding safety of therapy.

SUMMARY

Testosterone is a necessary component of female physiology acting both directly and indirectly through aromatization to estrogens. Reduction in testosterone levels in women can result in deleterious effects emotionally, sexually and/or physically. Testosterone therapy resulting in serum levels in the high-normal range can provide significant improvement in these areas. The use of exogenous androgens in women with symptoms suggestive of androgen deficiency but with low-normal serum levels remains controversial.

Postmenopausal hormone therapy: an Endocrine Society scientific statement

OBJECTIVE

Our objective was to provide a scholarly review of the published literature on menopausal hormonal therapy (MHT), make scientifically valid assessments of the available data, and grade the level of evidence available for each clinically important endpoint. PARTICIPANTS IN DEVELOPMENT OF SCIENTIFIC STATEMENT: The 12-member Scientific Statement Task Force of The Endocrine Society selected the leader of the statement development group (R.J.S.) and suggested experts with expertise in specific areas. In conjunction with the Task Force, lead authors (n = 25) and peer reviewers (n = 14) for each specific topic were selected. All discussions regarding content and grading of evidence occurred via teleconference or electronic and written correspondence. No funding was provided to any expert or peer reviewer, and all participants volunteered their time to prepare this Scientific Statement.

EVIDENCE

Each expert conducted extensive literature searches of case control, cohort, and randomized controlled trials as well as meta-analyses, Cochrane reviews, and Position Statements from other professional societies in order to compile and evaluate available evidence. No unpublished data were used to draw conclusions from the evidence.

CONSENSUS PROCESS

A consensus was reached after several iterations. Each topic was considered separately, and a consensus was achieved as to content to be included and conclusions reached between the primary author and the peer reviewer specific to that topic. In a separate iteration, the quality of evidence was judged using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) system in common use by The Endocrine Society for preparing clinical guidelines. The final iteration involved responses to four levels of additional review: 1) general comments offered by each of the 25 authors; 2) comments of the individual Task Force members; 3) critiques by the reviewers of the Journal of Clinical Endocrinology & Metabolism; and 4) suggestions offered by the Council and members of The Endocrine Society. The lead author compiled each individual topic into a coherent document and finalized the content for the final Statement. The writing process was analogous to preparation of a multiauthored textbook with input from individual authors and the textbook editors.

CONCLUSIONS

The major conclusions related to the overall benefits and risks of MHT expressed as the number of women per 1000 taking MHT for 5 yr who would experience benefit or harm. Primary areas of benefit included relief of hot flashes and symptoms of urogenital atrophy and prevention of fractures and diabetes. Risks included venothrombotic episodes, stroke, and cholecystitis. In the subgroup of women starting MHT between ages 50 and 59 or less than 10 yr after onset of menopause, congruent trends suggested additional benefit including reduction of overall mortality and coronary artery disease. In this subgroup, estrogen plus some progestogens increased the risk of breast cancer, whereas estrogen alone did not. Beneficial effects on colorectal and endometrial cancer and harmful effects on ovarian cancer occurred but affected only a small number of women. Data from the various Women's Health Initiative studies, which involved women of average age 63, cannot be appropriately applied to calculate risks and benefits of MHT in women starting shortly after menopause. At the present time, assessments of benefit and risk in these younger women are based on lower levels of evidence.

Testosterone and the breast

Although women have been treated with testosterone (T) for female sexual dysfunction since the 1950s, the role of T in normal female physiology is not yet fully defined. One of the major safety concerns of androgen therapy is whether androgens have a stimulatory effect on the breast that could lead to breast carcinomas. The proposed mechanisms for such stimulation include local estrogen production from the aromatase enzyme complex present in the breast tissue or by the direct stimulation of the androgen receptor. Predominant data from in vitro studies have shown that androgens actually have apoptotic and antiproliferative effects and not stimulatory effects. Animal models have shown similar results to in vitro studies, finding that androgens inhibit breast cancer growth. Prospective and retrospective epidemiological analyses have shown mixed outcomes, with no clear consensus regarding androgen use and breast cancer risk. Hyperandrogenism in patients with polycystic ovarian syndrome with elevated levels of endogenous T is not associated with an increased risk of breast cancer and may, in fact, be protective. Another human model with excess of T is female-to-male transgenderism, in which genotypic women are treated with large doses of exogenous T with no increased risk. High-dose androgen therapy also has been effective in treating patients with advanced breast cancer. Thus, the preponderance of data suggests that T use in females is not associated with an increased risk of breast carcinoma.

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.

Management of female sexual dysfunction in postmenopausal women by testosterone administration: safety issues and controversies

INTRODUCTION

A Food and Drug Administration advisory group has questioned the long-term safety of testosterone administration to postmenopausal women. Although only short-term data exist on safety from the double-blind, placebo-controlled trials, testosterone has been used for more than 50 years. Therefore, some data concerning the long-term safety issues must exist in the literature.

AIM

To review the published data concerning the safety of administration of testosterone to women.

METHODS

Review of published articles identified by a search of the Ovid databases and bibliographies from articles identified as dealing with the topics of testosterone or androgen treatment of women.

RESULTS

The major adverse reactions to exogenous androgens are the expected androgenic side effects of hirsutism and acne. High-density lipoprotein levels may be decreased with oral androgens. There are insufficient long-term safety data regarding breast, endometrium, or heart safety to draw strong conclusions, although the data available to date are reassuring.

CONCLUSIONS

Testosterone administration to postmenopausal women that result in physiological to slightly supraphysiological serum-free testosterone levels is safe for at least 2 years.

Safety of testosterone treatment in postmenopausal women

OBJECTIVE

To critically examine the safety of T therapy given to postmenopausal women.

DESIGN

MEDLINE literature review, cross-reference of published data, and review of Food and Drug Administration transcripts.

RESULT(S)

Although some retrospective and observational studies provide some long-term safety data, most prospective studies have had a duration of 2 years or less. In addition, with the exception of the female-to-male transsexuals, T was administered in conjunction with estrogens or estrogens and progestins, which confound the interpretation of some of the studies. The major adverse reactions are the androgenic side effects of hirsutism and acne. There does not appear to be an increase in cardiovascular risk factors, with the exception of a lowering of high-density lipoprotein with oral T. There are little data on endometrial safety, and most of the experimental data support a neutral or beneficial effect in regards to breast cancer. There does not appear to be an increased risk of hepatotoxicity, neurobehavioral abnormalities, sleep apnea, or fetal virilization (in premenopausal women) with the physiologic treatment doses of T.

CONCLUSION(S)

Except for hirsutism and acne, the therapeutic administration of T in physiologic doses is safe for up to several years. However, prospectively collected long-term safety studies are needed to provide a greater degree of assurance.

Breast cancer risk factors in relation to breast density (United States)

Objectives

Evaluate known breast cancer risk factors in relation to breast density.

Methods

We examined factors in relation to breast density in 144,018 New Hampshire (NH) women with at least one mammogram recorded in a statewide mammography registry. Mammographic breast density was measured by radiologists using the BI-RADS classification; risk factors of interest were obtained from patient intake forms and questionnaires.

Results

Initial analyses showed a strong inverse influence of age and body mass index (BMI) on breast density. In addition, women with late age at menarche, late age at first birth, premenopausal women, and those currently using hormone therapy (HT) tended to have higher breast density, while those with greater parity tended to have less dense breasts. Analyses stratified on age and BMI suggested interactions, which were formally assessed in a multivariable model. The impact of current HT use, relative to nonuse, differed across age groups, with an inverse association in younger women, and a positive association in older women (p < 0.0001 for the interaction). The positive effects of age at menarche and age at first birth, and the inverse influence of parity were less apparent in women with low BMI than in those with high BMI (p = 0.04, p < 0.0001 and p = 0.01, respectively, for the interactions). We also noted stronger positive effects for age at first birth in postmenopausal women (p = 0.004 for the interaction). The multivariable model indicated a slight positive influence of family history of breast cancer.

Conclusions

The influence of age at menarche and reproductive factors on breast density is less evident in women with high BMI. Density is reduced in young women using HT, but increased in HT users of age 50 or more.

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.

Postmenopausal testosterone therapy and breast cancer risk

BACKGROUND

Testosterone therapy is being increasingly used in the management of postmenopausal women. However, as clinical trials have demonstrated a significantly increased risk of breast cancer with oral combined estrogen-progestin therapy, there is a need to ascertain the risk of including testosterone in such regimens.

OBJECTIVE

Evaluation of experimental and epidemiological studies pertaining to the role of testosterone in breast cancer.

DESIGN

Literature review.

SETTING

The Jean Hailes Foundation, Research Unit.

MAIN OUTCOME MEASURES

Mammary epithelial proliferation, apoptosis and breast cancer.

RESULTS

In experimental studies, testosterone action is anti-proliferative and pro-apoptotic, and mediated via the AR, despite the potential for testosterone to be aromatized to estrogen. Animal studies suggest that testosterone may serve as a natural, endogenous protector of the breast and limit mitogenic and cancer promoting effects of estrogen on mammary epithelium. In premenopausal women, elevated testosterone is not associated with greater breast cancer risk. The risk of breast cancer is also not increased in women with polycystic ovary syndrome who have chronic estrogen exposure and androgen excess. However, in postmenopausal women, who are oestrogen deplete and have increased adipose aromatase activity, higher testosterone has been associated with greater breast cancer risk.

CONCLUSION

Available data indicate the inclusion of testosterone in estrogen-progestin regimens has the potential to ameliorate the stimulating effects of hormones on the breast. However, testosterone therapy alone cannot be recommended for estrogen deplete women because of the potential risk of enhanced aromatisation to estrogen in this setting.

Testosterone effects on the breast: implications for testosterone therapy for women

Androgens have important physiological effects in women. Postmenopausal androgen replacement, most commonly as testosterone therapy, is becoming increasingly widespread. This is despite the lack of clear guidelines regarding the diagnosis of androgen insufficiency, optimal therapeutic doses, and long-term safety data. With respect to the breast specifically, there is the potential for exogenous testosterone to exert either androgenic or indirect estrogenic actions, with the latter potentially increasing breast cancer risk. In experimental studies, androgens exhibit growth-inhibitory and apoptotic effects in some, but not all, breast cancer cell lines. Differing effects between cell lines appear to be due primarily to variations in concentrations of specific coregulatory proteins at the receptor level. In rodent breast cancer models, androgen action is antiproliferative and proapoptotic, and is mediated via the androgen receptor, despite the potential for testosterone and dehydroepiandrosterone to be aromatized to estrogen. The results from studies in rhesus monkeys suggest that testosterone may serve as a natural endogenous protector of the breast and limit mitogenic and cancer-promoting effects of estrogen on mammary epithelium. Epidemiological studies have significant methodological limitations and provide inconclusive results. The strongest data for exogenous testosterone therapy comes from primate studies. Based on such simulations, inclusion of testosterone in postmenopausal estrogen-progestin regimens has the potential to ameliorate the stimulating effects of combined estrogen-progestin on the breast. Research addressing this is warranted; however, the number of women that would be required for an adequately powered randomized controlled trial renders such a study unlikely.

[Ductal in situ carcinoma: is it ethical to consider the breast conserving therapy as a standard?]

The increasing incidence of DCIS during the past 20 years needs a continuous evaluation of the treatment strategies and a multidisciplinary decision process. The management of the DCIS remains a challenging issue in 2003. Mastectomy should still be considered as the reference treatment which is able to guarantee cure in almost all cases, whereas breast conserving surgery followed by radiation therapy is associated with 7-10% of local recurrence. However, the increasing knowledge of the predictive factors of the local recurrence allows to propose a conservative treatment strategy to a large amount of patients, without negative impact on their prognosis. This review presents the arguments that permit to justify the reasoned choice of the different therapeutic options according to the clinico-pathological situations.

Secular stability and reliability of measurements of the percentage of dense tissue on mammograms

Elevated mammographic density is associated with increased risk of breast cancer. We conducted a reliability study on mammographic density assessments to determine their potential usefulness for projecting individual breast cancer risk. We used baseline screening mammograms from 7251 women in the Breast Cancer Detection Demonstration Project (BCDDP). Repeated measurements from the same images were used to assess measurement variability by an experienced evaluator. Intraclass correlations of assessments over time usually exceeded 0.9, indicating usefulness for prospective applications. Data also indicated it may be reasonable to include cases identified in the first year of screening together with other cases in developing a risk model. Older ages and increased weight were associated with decreased mammographic density. The density of the right breast slightly exceeded that of the left. Among women who developed breast cancer, the baseline mammographic density of the ipsilateral (diseased) breast was 0.53 (95% confidence interval (CI) 0.20-0.86) percentage units higher than in the contralateral breast.

Breast cancer and hormonal replacement therapy

Understanding the association between hormone replacement therapy (HRT), the diagnosis of breast cancer, and the clinical outcome of women who develop breast cancer in the setting of HRT continue to present important challenges for health professionals and the public. The general impression in the medical community is that breast cancer is diagnosed more frequently after prolonged HRT; however, whether a causative relationship exists between HRT and breast cancer remains uncertain. Despite the increase in breast cancer diagnosis, clinical outcome of the disease appears favorable for women who develop breast cancer after HRT; HRT users tend to present with more localized tumors that exhibit favorable histology, and overall death from breast cancer appears reduced. The history of breast cancer constitutes a contraindication for HRT as a general rule, based on the concern that HRT may activate dormant cancer cells. Direct evidence for this practice is very limited; available studies are small and mostly retrospective, but do not indicate an adverse effect of HRT on breast cancer recurrence. In reaching a clinical decision regarding HRT, the expected benefits (largely improvement of menopausal symptoms) must be weighed against the potential risks of HRT (especially breast cancer) for each individual woman.

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.

Detection of estrogen DNA-adducts in human breast tumor tissue and healthy tissue by combined nano LC-nano ES tandem mass spectrometry

For the first time estrogen DNA-adducts were identified in DNA human breast tumor tissue using nano-LC coupled to nano-Electrospray Tandem Mass Spectrometry. Normal breast tissue was analyzed analogously. The data obtained in the five breast tumor and five adjacent normal tissue samples were compared qualitatively, but no straightforward difference was observed. Prior to LC-MS analysis the DNA was enzymatically hydrolyzed to a nucleoside pool. The DNA-hydrolysates were directly injected onto a column switching system developed for on-line sample clean-up and subsequent analysis of the DNA-adducts. In four patients using Premarin, DNA-adducts of 4-hydroxy-equilenin (4OHEN) were detected. All except three samples contained DNA-adducts from 4-hydroxy-estradiol or 4-hydroxy-estrone. Also DNA isolated from eight alcohol fixed and paraffin embedded breast tumor tissue showed the presence of different estrogen DNA-adducts. Worthwhile mentioning is the presence of adducts responding to m/z 570 > m/z 454 transition. This is a well-known SRM-transition indicative for the presence of the 2'-deoxyguanosine (dGuo) adduct of Benzo[a]pyrene.

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 risk assessment models: applicability to African-American women

BACKGROUND

Mortality rates are higher among African-American women with breast cancer than they are among white women. This population subset can benefit from available risk reduction strategies. Optimal public health gains from chemoprevention strategies depend on the ability to assess accurately the risk for the individual. However, it is not known if existing breast cancer prediction models are accurate predictors of the disease among African-American women.

METHODS

Literature was reviewed for breast cancer risk prediction models and their validation studies. Reported data were also reviewed regarding the strength of established breast cancer risk factors for African-American women.

RESULTS

The two currently accepted breast cancer risk assessment models, the Gail Model and the Claus Model, were designed primarily to provide risk assessments for white women. Neither model has been validated in African-American women. Reported data are inconsistent regarding the prevalence and strength of risk factors included in these models.

CONCLUSIONS

Efforts should be made to validate existing risk assessment models in African-American women and future research should be directed at the identification of more reliable risk assessment features.

Hereditary Breast Cancer: Risk Assessment Is the Easy Part

Individuals who seek genetic testing to determine hereditary risk of breast cancer may not be aware that genetic testing is uninformative in many high-risk families or that they may be at increased risk of other cancers as well. Many mistakenly believe that current genetic testing provides definitive information about the magnitude of cancer risk to carriers. This article describes the assessment of hereditary risk by pedigree analysis, epidemiology, and genetic testing within the cancer risk assessment and counseling setting, and discusses other information that helps patients to make informed health care decisions. Because the risk of ovarian cancer is increased in many families at high risk of breast cancer, information about prophylactic oophorectomy and hormone replacement therapy is essential. A case history is presented to show the efficacy of cancer risk assessment and counseling when genetic testing is uninformative.

Breast carcinoma in situ: risk factors and screening patterns

BACKGROUND

Risk factors associated with invasive breast cancer are well documented, but those associated with breast carcinoma in situ are not well defined.

METHODS

We conducted a population-based, case-control study among female residents of Connecticut to identify risk factors for breast carcinoma in situ. Case patients, diagnosed with ductal carcinoma in situ (DCIS) (n = 875) or lobular carcinoma in situ (LCIS) (n = 123), were matched by 5-year age groups with control subjects (n = 999). Case patients were diagnosed between September 15, 1994, through March 14, 1998, and all subjects were between the ages of 20 and 79 years. Information on risk factors and cancer-screening history was collected by telephone interviews. Conditional logistic regression was used to determine odds ratios (ORs) for the association of these factors with the risk of DCIS and LCIS.

RESULTS

Case patients with DCIS were more likely than control subjects to report a family history of breast cancer (OR = 1.48; 95% confidence interval [CI] = 1.19 to 1.85) or previous breast biopsy (OR = 3.56; 95% CI = 2.86 to 4.43). They also had fewer full-term pregnancies (OR = 0.86; 95% CI = 0.80 to 0.93) and were older at first full-term pregnancy (OR for being 20-29 years old relative to being <20 years old = 1.68; 95% CI = 1.17 to 2.43) and at menopause (OR for being > or =55 years old relative to being <45 years old = 1.71; 95% CI = 1.05 to 2.77). DCIS case patients were more likely than control subjects to have had a mammographic examination (OR = 2.46; 95% CI = 1.78 to 3.40) or an annual clinical breast examination (OR = 1.83; 95% CI = 1.48 to 2.26). DCIS patients and control subjects did not differ with respect to oral contraceptive use, hormone replacement therapy, alcohol consumption or smoking history, or breast self-examination. Associations for LCIS were similar.

CONCLUSIONS

The risk factors associated with DCIS and LCIS are similar to those associated with invasive breast cancer. Diagnosis of DCIS is associated with increased mammography screening.

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.

Equilenin-2'-deoxynucleoside adducts: analysis with nano-liquid chromatography coupled to nano-electrospray tandem mass spectrometry

The interaction of 4-hydroxy metabolites of estrogens with DNA leads to the formation of DNA adducts. These adducts are believed to play an important role in the incidence of breast and endometrial cancer. In order to be able to analyze these adducts in in vivo samples a method based upon the coupling of miniaturized liquid chromatography (LC) to electrospray tandem mass spectrometry (ES-MS/MS) was developed for the analysis of the adducts formed with 4-hydroxyequilenin. In vitro synthesized adducts obtained by the reaction of 4-hydroxyequilenin with the main 2'-deoxynucleosides were separated on a Hypersyl C(18) BDS nano-HPLC column (15 cm x 75 microm i.d.) at a flow-rate of 300 nl min(-1) using gradient elution with CH(3)OH--0.2% CH(3)COOH in H(2)O. The column was coupled, in combination with a column switching system, to a nano-electrospray interface. Analysis of the low- and high-resolution low-energy collision-activated dissociation product ion spectra of normal and deuterated adducts supported earlier data demonstrating equilenin to form different isomeric adducts, except with thymidine, for which no adducts were found. The nano-HPLC column-switching ES-MS system was tested for its sensitivity on a triple-quadrupole instrument, and detection limits down to 197 fg in the single reaction monitoring mode were obtained for semi-preparatively isolated equilenin--2'-deoxyguanosine adduct.

Biopsy confirmed benign breast disease, postmenopausal use of exogenous female hormones, and breast carcinoma risk

BACKGROUND

A history of proliferative benign breast disease has been shown to increase the risk of developing breast carcinoma, but, to the authors' knowledge, how postmenopausal exogenous female hormone use, in general, has affected breast carcinoma risk among women with a history of proliferative breast disease with or without atypia has not been well established.

METHODS

In the current case-control study, nested within the Nurses' Health Study, benign breast biopsy slides of 133 postmenopausal breast carcinoma cases and 610 controls with a history of benign breast disease, were reviewed. Reviewers had no knowledge of case status.

RESULTS

Women with proliferative disease without atypia had a relative risk for postmenopausal breast carcinoma of 1.8 (95%, confidence interval [CI]: 1.1 to 2.8), and women with atypical hyperplasia had a relative risk of 3.6 (95%, CI: 2.0 to 6.4) compared with women who had nonproliferative benign histology. Neither current postmenopausal use of exogenous female hormones nor long term use for 5 or more years further increased the risk of breast carcinoma in the study population beyond that already associated with their benign histology.

CONCLUSIONS

Women who had proliferative benign breast disease, with or without atypia, were at moderately to substantially increased risk of developing postmenopausal breast carcinoma compared with women who had nonproliferative benign conditions. In the current study, postmenopausal exogenous female hormone use in general did not further increase the breast carcinoma risk for women with proliferative benign breast disease. However, the analysis did not exclude the possibility of increased risk with a particular hormone combination or dosage.

[Effects of hormone replacement therapy for menopause on prognostic factors of breast cancer]

AIM

Hormone replacement therapy (HRT) is widely used by post-menopausal women. Although this treatment may slightly increase the incidence of breast cancer, more and more cases are diagnosed while women are taking HRT. The purpose of this study was to ascertain the influence of HRT on prognostic factors and outcome of breast cancer. Data on all breast cancer patients, including precise information on HRT, was prospectively and systematically recorded in a data base.

PATIENTS AND METHODS

From 1990 to 1998, 1223 post-menopausal women fulfilled the eligibility criteria for this study. The clinical features, laboratory findings and survival rates in 245 HRT users who developed breast cancer while being treated were compared with those of 245 matched breast cancer patients who had never received HRT.

RESULTS

Patients who developed breast cancer during HRT had fewer locally advanced cancers and smaller and better-differentiated cancers. Estradiol receptivity was quantitatively lower in users. Metastasis-free survival were better for the users.

CONCLUSION

We conclude that HRT does not affect the prognosis of breast cancer. Regular surveillance during HRT allows early detection of smaller lesions. The higher number of well-differentiated cancers and the distribution of hormone receptivity may reflect interaction between neoplastic tissue and exogenous hormones.

Hormone replacement therapy and breast cancer risk

The female breast is subject to a lifetime of hormonal control. After menopause, breast tissue becomes quiescent when estrogens drop to low levels. Menopause-associated hormonal decreases produce short- and long-term consequences that can be treated successfully by hormone replacement therapy (HRT). Despite the beneficial effects of HRT, the potential risk of breast cancer is a concern of both women and physicians. The available data indicate that HRT administered for longer than 5 years moderately increases the risk of breast cancer, but overall the benefits outweight the potential risk.

Overview of women's decision making regarding elective hysterectomy, oophorectomy, and hormone replacement therapy

Over 600,000 hysterectomies are performed each year in the United States, the majority of which are to improve quality of life for perimenopausal women. Hysterectomy rates for common conditions differ between African American and white women, and African American women undergo surgery at a younger age for most diagnoses. Many hysterectomies are accompanied by elective oophorectomy, and hormone replacement therapy (HRT) is commonly used, especially among women experiencing surgical menopause, despite questions about its long-term benefits and risks. Despite the high rates of hysterectomy in the United States, little is known about how women make decisions regarding this surgery and, in particular, how ethnic and cultural factors may influence these decisions. This article provides a review of what is currently known about the epidemiology of hysterectomy, oophorectomy, and HRT use and identifies gaps in knowledge about women's decision making, with a special focus on ethnic variations and cultural influences, issues addressed by the Ethnicity, Needs, and Decisions of Women (ENDOW) project.

Who Should Receive Hormone Replacement Therapy?

Coronary heart disease is the leading cause of death in women in the United States and increases dramatically in postmenopausal women. The following review summarizes the known benefits and risks of hormone replacement therapy and gives recommendations for use of hormone replacement in women. Estrogen may play a role in preventing the development of atherosclerosis in women by raising levels of HDL cholesterol, lowering levels of LDL cholesterol and lipoprotein (a), lowering levels of fibrinogen and plasminogen activator inhibitor-1, dilating coronary arteries, preventing the oxidation of LDL cholesterol, decreasing the proliferation and migration of smooth muscle cells, and decreasing the production of inflammatory cell activators. These antiatherogenic effects of estrogen may translate into clinical benefits. A meta-analysis of 31 studies yielded a 44% reduction in the risk of coronary heart disease in women taking estrogen alone. Unopposed estrogen is associated with an increased risk of endometrial cancer; therefore, progestin is added to estrogen in women with an intact uterus. Less is known about the effect of the combination of estrogen and a progestin on the risk of coronary heart disease. Estrogen is also beneficial in the prevention of osteoporosis; however, long-term use of estrogen alone and estrogen in combination with progestin may increase the risk for breast cancer. Mathematical modeling predicted that women with no risk for cardiovascular disease, cancer, or osteoporosis may gain 0.9 years of life with the use of estrogen alone; women with risk factors for cardiovascular disease can expect to gain 1.5 years of life; and women with coronary heart disease at the age of 50 can expect to gain 2.1 years of life. The current American College of Physicians recommendations for hormone replacement are as follows: (1) All women should be considered; (2) women with a hysterectomy should receive estrogen alone; (3) women at risk for, or with, coronary heart disease are most likely to benefit from estrogen; with an intact uterus, progestin must be added; (4) risks of estrogen may outweigh benefits in women at increased risk for breast cancer. Definitive guidelines for the treatment of women must await the results of randomized clinical trials in the ongoing Women's Health Initiative. These will not be available for several years, and until then any recommendations for women will have to be judged from estimates of risk rather than of benefit from reduction of risk. The decision whether to initiate estrogen replacement in postmenopausal women is one that still needs to be made on an individual patient basis.

Postmenopausal hormone replacement in the woman with a reproductive risk factor for breast cancer

OBJECTIVE

to assess the interaction between postmenopausal hormone replacement therapy (HRT) and various reproductive risk factors for breast cancer such as early menarche, late menopause, late first delivery and nulliparity.

DESIGN

three cohort studies and fourteen case control studies, published between 1975 and 1997, provided relative risks (RRs) of HRT use in women with, as well as in those without, a reproductive risk factor for breast cancer.

METHODS

using an additive RR model reported before, we investigated whether the RR for breast cancer in women with a combination of HRT and a given reproductive risk factor result from a simple addition of RRs of HRT on the one hand, and of the pre-existing reproductive risk factor on the other hand, or that synergism between both risk factors occurs.

RESULTS

simple addition of RRs was shown in the case of early menarche and late menopause. Less increase of risk, suggesting antagonism, was found for both late first delivery and nulliparity in combination with HRT use.

CONCLUSION

we could not observe any synergistic effect of the combined risks of any of the following reproductive risk factors for breast cancer: early menarche, late menopause, late first delivery or nulliparity on the one hand, with the risk resulting from HRT use on the other hand. Therefore, as far as the risk of breast cancer is concerned, the use of HRT appears not to be highly detrimental in women with a reproductive breast cancer risk factor, as it results in not more than a simple addition of risks at the most.

The effect of estrogen usage on the subsequent hormone receptor status of primary breast cancer

In order to determine if prior use of exogenous estrogens was related to the estrogen receptor (ER) content of primary breast cancers, a retrospective analysis was performed from 536 patients with invasive breast cancer. The patient's age, menopausal status, oral contraceptive or estrogen replacement therapy usage, and the ER and progesterone receptor (PR) content of the breast cancer were recorded for all patients. Hormone usage in premenopausal and postmenopausal patients was compared to ER and PR levels in primary breast cancers using non-parametric testing. Complete information was available from 508 (193 premenopausal and 315 postmenopausal) patients. Breast cancers were ER positive in 72% of postmenopausal patients and 57% of premenopausal patients. The majority of patients received 'Some' form of hormone therapy (111 of 193 premenopausal patients and 233 of 315 postmenopausal patients). Significantly more estrogen receptors were detected in tumors from patients receiving 'some' estrogen therapy compared to 'never' users. Postmenopausal patients 'never receiving estrogen therapy had a lower rate of ER positive tumors (62%) compared to 'some' users (75%, chi2 = 4.99, p < 0.05). The same relationship was seen for PR ('never' users 44% positive, 'some' users 58% positive, chi2 = 5.19, p < 0.05). We conclude that postmenopausal patients who received 'some' estrogen therapy are more likely to have breast cancers that are estrogen receptor and progesterone receptor positive.

Perception of future health risks in mid-aged women: estimates with and without behavioural changes and hormone replacement therapy

Cardiovascular disease (CVD) and cancer are major causes of death for women, and osteoporosis negatively impacts upon the health and quality of life of many older women. There is evidence that risk of developing these diseases is partially determined by lifestyle factors, such as physical activity, diet and smoking, as well as being influenced by hormonal changes during the menopause. Participation in preventive strategies will be influenced by women's perceptions of the relative risks of developing these diseases, and beliefs about the effectiveness of the particular strategy. In this study, 103 mid-aged women were asked about their health and health behaviours and to estimate: (1) their future likelihood of developing CVD, osteoporosis and breast cancer; and (2) their future likelihood of developing diseases (a) if they improved their health behaviours, and (b) if they used hormone replacement therapy (HRT) for 5 years. Women believed that improving their health behaviours (diet, physical activity, smoking) would reduce their risks of CVD and osteoporosis, although modest reductions were expected. Breast cancer was not seen as significantly modifiable by lifestyle changes. They believed that taking HRT would significantly reduce their risk of osteoporosis, increase their risk of breast cancer, but not alter their risk of developing CVD. The findings are considered in the context of health psychology models of behaviour change and have implications for health promotion for mid-aged women.

Postmenopausal estrogen replacement therapy is associated with adverse breast cancer prognostic indices

Previous studies have reported that breast cancer patients who used estrogen replacement therapy (ERT) have more favorable tumor characteristics and decreased mortality compared with nonusers. However, these findings may be due partly to increased medical surveillance in ERT users and detection of early stage tumors. Postmenopausal women with biopsy-proven breast cancer (n = 108) were identified based on their participation in screening mammography. Based on self-administered questionnaires completed at the time of mammography, 29 of these were users of ERT. Tumor characteristics (histology size, nodal status, and estrogen receptor content) of ERT users were compared with those of nonusers. After adjusting for potentially confounding variables, the odds ratios (OR) describing the relationship between ERT use and the risk of invasive histopathology (OR = 1.35, 95% CI = 0.48, 3.75), positive nodes (OR = 2.43, 95% CI = 0.59, 10.10), size > or = 2.0 cm (OR = 2.34, CI = 0.66, 8.27), or negative estrogen receptor status (OR = 1.08, 95% CI = 0.18, 9.38) were > 1, although none reached statistical significance. When the subjects were separated into two prognostic groups based on the presence or absence of adverse prognostic indices, ERT users had a statistically significantly increased risk of being in the poor prognostic group (tumor size > or = 2.0 cm or positive nodes or negative estrogen receptor content) (OR = 4.48, 95% CI = 1.10, 18.30). The risk was highest in current users (OR = 6.28, 95% CI = 1.16, 34.00), users for 5 or more years (OR = 7.77, 95% CI = 1.09, 55.60), and users of nonconjugated estrogen (OR = 9.63, 95% CI = 1.18, 78.60). Although our sample size is small and we do not currently have information on long-term outcomes, the findings from this screening population suggest that ERT may have an adverse effect on important breast cancer prognostic indices.

Hormone replacement therapy before breast cancer diagnosis significantly reduces the overall death rate compared with never-use among 984 breast cancer patients

Nine hundred and eighty-four breast cancer patients were interviewed regarding exogenous hormonal use. This represents a random sample of breast cancer patients in Southern Sweden referred to the Department of Oncology at Lund for treatment between 1978 and 1997 (excluding 1980 and 1981) with a 100% follow-up. Ever-use of hormone replacement therapy (HRT) prior to diagnosis was significantly associated with a longer overall survival in women with their breast cancer diagnosed at ages 45 and above, relative risk (RR) of dying 0.73 (95% confidence interval (CI) 0.62-0.87; P = 0.0005). Ever use of HRT prior to breast cancer diagnosis was significantly positively associated with overall longer survival after adjustment for T-stage, N-stage, M-stage, year of diagnosis and age at diagnosis, RR of dying 0.78 (95% CI 0.65-0.93; P = 0.006). Hormone replacement therapy use and oestrogen receptor positivity were independently significantly associated with overall longer survival, P = 0.005 and P < 0.0001, respectively, in one model. HRT use and progesterone receptor positivity were also independently significantly associated with longer overall survival, P = 0.003 and P = 0.0003, respectively, in another model. The mode of diagnosis was known in 705 women. Mammography screening was not more common among HRT users compared with never-users, where this information was available. Both mammography screening and HRT use were independently associated with longer survival, P = 0.002 and P = 0.038 respectively.

Breast-cancer risk following long-term oestrogen- and oestrogen-progestin-replacement therapy

While use of hormone-replacement therapy (HRT) effectively alleviates menopausal symptoms and prevents osteoporosis and possibly cardiovascular disease, there is concern of a detrimental impact on breast-cancer risk. There is a particular lack of data regarding the effect of long-term use of oestrogen-progestin combinations on breast-cancer risk. We conducted a large epidemiological study in Sweden, where combined oestrogen-progestin treatment has been predominant, to examine the influence of different regimens of menopausal hormone therapy on breast-cancer risk. In this population-based case-control study, 3,345 women aged 50 to 74 years with invasive breast cancer (84% of all eligible) and 3,454 controls of similar age (82% of all selected) were included. Mailed questionnaires and telephone interviews were used to collect detailed information on use of hormone replacement and on potential confounding factors. Odds ratios (OR) and 95% confidence intervals (CI) were estimated through multiple logistic regression. There was a trend of increasing breast-cancer risk with duration of oestrogen/oestrogen-progestin use (OR for women treated at least 10 years, 2.43; 95% CI, 1.79-3.30, as compared to never-users), with statistically significant estimates only for women with BMI<27 kg/m2. Excess risks were observed to current use and use that ceased more than 10 years ago (OR for women treated at least 5 years, OR was 2.68, 95% CI, 2.09-3.42, and OR 2.57, 95% CI, 1.28-5.15, as compared with never-users, respectively). A positive association which was noted for use of oestrogen combined with testosterone-derived progestins appeared especially pronounced with continuously combined regimens. Long-term use of replacement oestrogens with or without progestins may substantially increase the incidence of post-menopausal breast cancer, particularly among non-obese women.