Estrogen replacement therapy and the risk of breast cancer: results from the case-control surveillance study

Effect of contraceptive hormonal therapy on mammographic breast density: A longitudinal cohort study

PURPOSE

Evaluate the longitudinal relationship between mammographic density and hormonal contraceptive use in late reproductive-aged women.

METHODS

Patients aged 35-50 years old who underwent 5 or more screening mammograms within a 7.5-year period between 2004 and 2019 in a single urban tertiary care center were randomly selected. Patients were categorized into four cohorts based on hormonal contraceptive exposure during a 2-year lead-in period and a 7.5-year study period: 1) never exposed, 2) always exposed, 3) interval hormonal contraceptive start, and 4) interval hormonal contraceptive stop. The primary outcome was difference in BI-RADS breast density category between initial and final mammograms.

RESULTS

Of the 708 patients included, long-term use of combined oral contraceptives or a levonorgestrel intrauterine device were not associated with an increase in breast density category over the 7.5-year study period, compared to those with no hormonal contraceptive exposure. Initiation of combined oral contraceptives was associated with an increase in breast density category (β = 0.31, P = 0.045); however, no difference in initial density category was noted between those exposed and those never exposed to combined oral contraceptives during the 2-year lead-in period, and discontinuation was not associated with a decrease in breast density category when compared to those with continuous exposure.

CONCLUSION(S)

Long-term use of combined oral contraceptives or a levonorgestrel intrauterine device was not associated with an increase in BI-RADS breast density category. Initiation of a combined oral contraceptive was associated with an increase in breast density category, although this may be a transient effect.

Risk factors for endometrial cancer in Black women

PURPOSE

The incidence of endometrial cancer (EC) has been increasing faster among Black women than among other racial/ethnic groups in the United States. Although the mortality rate is nearly twice as high among Black than White women, there is a paucity of literature on risk factors for EC among Black women, particularly regarding menopausal hormone use and severe obesity.

METHODS

We pooled questionnaire data on 811 EC cases and 3,124 controls from eight studies with data on self-identified Black women (4 case-control and 4 cohort studies). We analyzed cohort studies as nested case-control studies with up to 4 controls selected per case. We used logistic regression to estimate multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

We observed a positive association between BMI and EC incidence (P_trend < 0.0001) The OR comparing BMI ≥ 40 vs. < 25 kg/m² was 3.92 (95% CI 2.91, 5.27). Abdominal obesity among those with BMI < 30 kg/m² was not appreciably associated with EC risk (OR 1.21, 95% CI 0.74, 1.99). Associations of reproductive history with EC were similar to those observed in studies of White women. Long-term use of estrogen-only menopausal hormones was associated with an increased risk of EC (≥ 5 years vs. never use: OR 2.08, 95% CI: 1.06, 4.06).

CONCLUSIONS

Our results suggest that the associations of established risk factors with EC are similar between Black and White women. Other explanations, such as differences in the prevalence of known risk factors or previously unidentified risk factors likely underlie the recent increases in EC incidence among Black women.

Progestogens are the problem in hormone replacement therapy: Time to reappraise their use

Combined (estrogen and a progestogen) hormone replacement therapy (cHRT) is associated with an increased risk of breast cancer, while estrogen replacement therapy is not. Whatever the underlying mechanism, it is the progestogen in cHRT that seems to increase the risk. Fear of breast cancer is a major limiting factor in the use of hormone replacement therapy, and when women discontinue cHRT because of side effects, the latter are often attributable to the progestogen component. cHRT is given to women with an intact uterus to protect against the effects of un-opposed estrogen such as an increased risk of endometrial cancer. Estrogen replacement therapy suffices for women with a prior hysterectomy. There is a clear distinction in risk and side effect profile between cHRT and estrogen replacement therapy. Apart from being the most effective treatment for menopausal symptoms, estrogen prevents osteoporosis, and may also have a potential role in prevention of Alzheimer’s Dementia, now the biggest killer of women in the United Kingdom. Evidence also suggests that progestogens could compromise the dementia-preventative effect of estrogen. Given the immense therapeutic and preventative potential of estrogen, the use of progestogens in cHRT needs re-appraisal. The levonorgestrel intrauterine system (LNg-IUS) could reduce breast cancer risk while protecting the endometrium. Other approaches to the safe use of progestogens await research.

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.

Risk factors of breast cancer: a systematic review and meta-analysis

The etiology of breast cancer might be explained by 2 mechanisms, namely, differentiation and proliferation of breast epithelial cells mediated by hormonal factors. We performed a systematic review and meta-analysis to update effects of risk factors for both mechanisms. MEDLINE and EMBASE were searched up to January 2011. Studies that assessed association between oral contraceptives (OC), hormonal replacement therapy (HRT), diabetes mellitus (DM), or breastfeeding and breast cancer were eligible. Relative risks with their confidence intervals (CIs) were extracted. A random-effects method was applied for pooling the effect size. The pooled odds ratios of OC, HRT, and DM were 1.10 (95% CI = 1.03-1.18), 1.23 (95% CI = 1.21-1.25), and 1.14 (95% CI = 1.09-1.19), respectively, whereas the pooled odds ratio of ever-breastfeeding was 0.72 (95% CI = 0.58-0.89). Our study suggests that OC, HRT, and DM might increase risks, whereas breastfeeding might lower risks of breast cancer.

Hormone replacement therapy, family history, and breast cancer risk among postmenopausal women

BACKGROUND

Evidence is mixed regarding how familial predisposition to breast cancer affects the relation between hormone replacement therapy and risk of postmenopausal breast cancer. We investigated whether the risk difference for invasive breast cancer attributable to estrogen plus progesterone replacement therapy is greater among women with a first-degree family history of the disease.

METHODS

This study is a longitudinal follow-up of 16,608 postmenopausal women aged 50-79 years who were enrolled between 1993 and 2002 in the Women's Health Initiative randomized trial of estrogen plus progesterone replacement therapy versus placebo.

RESULTS

Three hundred forty-nine cases of invasive breast cancer occurred during a mean follow-up period of 5.6 years. The invasive breast cancer risk difference attributable to the hormone therapy was 0.007 among women with first-degree family history and 0.005 among the others, resulting in a negligible interaction contrast (IC = 0.002; 95% confidence interval = -0.014 to 0.018). The interaction contrast restricted to estrogen-receptor-positive invasive breast cancers was also negligible (IC = -0.006; 95% CI = -0.021 to 0.008).

CONCLUSION

Family history and estrogen plus progesterone replacement therapy have independent and noninteracting effects on the risk of invasive breast cancer among participants in the Women's Health Initiative randomized trial.

Menopausal hormone therapy and risk of breast cancer: a meta-analysis of epidemiological studies and randomized controlled trials

We conducted meta-analyses to assess the impact of menopausal hormone therapy (MHT) on the risk of incident invasive breast cancer (BC) in cohort studies (CS), case-control studies (CCS) and randomized controlled trials (RCTs) published 1989-2004. We used published data providing information upon unopposed estrogen therapy (ET), estrogen-progestin therapy (EPT) or all MHT combined. Major outcomes were MHT-associated overall risk of BC and change of risk per year used. There is a linear increase of overall risk by midterm year of case ascertainment based upon data of all study types for MHT and to a larger extent for EPT, not for ET. Effects are larger in CS than in CCS. Meta-analyses stratified by <1992 versus > or =1992 as midterm year of case ascertainment indicate larger summary risks for the latter period for all MHT analysed, in particular for EPT. Annual increases in BC risk for EPT across study types are 0-9%, for ET 0-3%. In conclusion, there is evidence that relative risks for BC risks by MHT, in particular EPT, have been increasing in recent years. Given the widespread use of MHT, and often long duration, more detailed knowledge about differential BC risks of both estrogens and progestins are necessary to minimize BC risk in symptomatic women who consider MHT.

Breast cancer risk with postmenopausal hormonal treatment

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

Hormone replacement therapy in postmenopausal women

BACKGROUND

For many years, hormone replacement therapy (HRT) was considered an effective method of restoring the relative protection from coronary artery disease enjoyed by premenopausal women compared with men of similar age. This view has been supported by a substantial number of basic science and observational studies.

DATA SOURCES

Results of recent randomized controlled trials have seriously challenged the concept of the protective value of HRT by showing that rather than decreasing the risk of coronary artery disease, HRT actually appears to increase it. In addition, it increases the risk for breast cancer, stroke, venous thromboembolism, and cholecystitis.

RESULTS

Despite some benefits such as increased bone mineral density and decreased risk of fracture and colorectal cancer, these data suggest that the risks of HRT outweigh the benefits.

CONCLUSIONS

HRT is no longer routinely recommended for prevention of chronic disease. We present the current scientific data, benefits, risks, and consequent clinical recommendations regarding HRT use in postmenopausal women.

Variability of breast cancer risk in observational studies of hormone replacement therapy: a meta-regression analysis

OBJECTIVES

A re-analysis of data from 51 epidemiological studies reported a significant 14% increase in the risk of breast cancer associated with the use of hormone replacement therapy (HRT). Unlike randomized trials, these observational studies varied in design and methods. This study was conducted to explore the impact of study design factors on the rate ratio.

METHODS

We performed a meta-regression analysis of 39 epidemiological studies of HRT and breast cancer. The rate ratio of breast cancer associated with ever use of HRT was evaluated in relation to study design, study period, country, primary study objective, method of exposure measurement, age control, adjustment factors related to reproduction and menopause, and the presence of breast cancer surveillance. We used stepwise multiple regression analysis, weighted by the inverse of the variance of the logarithm of the rate ratio, to estimate ratios of rate ratios for these factors.

RESULTS

Exposure measured by personal interview and/or medical record review was associated with a 14% lower rate ratio estimate as compared with telephone interview or self-administered questionnaire (P = 0.018). Among studies that did not adjust for age at menopause, the rate ratio was 12% lower if the primary objective was HRT effect than not (P = 0.016), while it was 43% higher among studies that adjusted for age at menopause (P = 0.042). An index that included as six desirable design features, breast cancer surveillance, matching of controls, more reliable exposure information, adjustment for age at menopause and reproductive risk factors, and as primary objective the effect of HRT suggests that studies with none of these properties would lead to a rate ratio estimate of 1.14 (95% CI: 1.00-1.29) while studies with all six properties would produce a rate ratio of 0.98 (95% CI: 0.83-1.15).

CONCLUSIONS

Design factors of epidemiological studies could be an alternative explanation for the reported 14% increase in the risk of breast cancer associated with the use of HRT.

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.

Risk of breast cancer with progestins: critical assessment of current data

Whether progestins protect against the risk of breast cancer or enhance that risk has been a major area of controversy over the past several years. Observational studies have reported conflicting results and experimental studies examining whether progestins exert mitogenic or anti-mitogenic actions on breast tissue report divergent results. Based upon a wide range of animal, epidemiologic and clinical data, most investigators agree that estrogens contribute to the development of breast neoplasms. However, the additional effect of progestins on this risk has been the subject of substantial discussion and controversy. A variety of experiments have been carried out using human breast cancer cells grown in vitro and as xenografts in nude mice. These studies demonstrated both mitogenic and anti-mitogenic effects depending upon the precise experimental conditions. Two potential reasons for these differences include differential metabolism of progestins into inhibitory pregnenes or stimulatory 5-alpha-reduced pregnanes or the presence of a protein (GPR 30) which allows the anti-mitogenic effects of progestins to be manifest. Based upon the conflicting nature of the results in experimental studies, we believe that only data in patients provide substantial insight into the actions of progestins on the intact human breast. Studies have now demonstrated that cell proliferation and breast density is higher during the luteal than during the follicular phase of the menstrual cycle. In postmenopausal women, long-term exposure to estrogen plus a progestin results in a marked enhancement of proliferation of the terminal duct lobular units as well as in breast density. These data, taken together, provide substantial evidence that progestins are mitogenic on the human breast when given long term to postmenopausal women. To critically evaluate the observational studies regarding breast cancer risk from progestins, we developed a set of stringent criteria for acceptance of individual studies. Four of the five studies meeting these criteria reported a greater risk of breast cancer with combination estrogen/progestin regimens than with estrogen alone. More importantly, the first randomized, prospective, controlled trial of the risk of breast cancer with an estrogen/progestin combination (the Women's Health Initiative Study) has now been published. This study reported a 26% increased relative risk of breast cancer with the estrogen/progestin combination. Based upon these data, we believe that progestins do add to the risk of breast cancer over and above that imparted by estrogen alone. The attributable risk during use for 5 years or less is small but increases logarithmically during long-term use. The majority of data regarding progestins are derived from regimens using MPA. However, we conclude from our analysis that the burden of proof regarding progestins has now shifted. One must now prove that an estrogen/progestin combination is safe with respect to breast cancer rather than having to prove it harmful.

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.

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.

Hormone replacement therapy for bone protection in multiparous women: when to initiate it

OBJECTIVE

Hormone replacement therapy is used in postmenopausal women to improve symptoms of menopause and to protect bone and the cardiovascular system. We have evaluated the effects of parity in terms of number of deliveries on bone density and fracture risk at different ages.

STUDY DESIGN

We evaluated 1875 Hispanic women > or =50 years old (61.3 +/- 8.3 years), 425 with a history of nonselective fractures and 1450 without previous fractures. Body mass index was 27.3 +/- 4.3 kg/m(2). Bone mineral densities were determined for the total body in 1468 cases, the femur in 221 cases, and the lumbar spine in 189 cases. Women were classified according to lifetime number of deliveries (from 0 to > or =5), and bone mineral densities and odds ratios for fracture risk were calculated relative to the number of deliveries.

RESULTS

Bone mineral densities in total body, pelvis, and legs and total calcium and total mineral contents increased (P <.001) with > or =2 deliveries among women 50 to 59 years old but not among those > or =70 years old. The prevalence of fractures was higher in nulliparous than in multiparous women at all ages. Fracture risk was lower in multiparous women at all age groups, including those > or =70 years old (odds ratio, 0.47; 95% confidence interval, 0.26-0.84; P <.006).

CONCLUSION

Bone mineral density increases with the number of deliveries until the age of 69 years. Fracture prevalence and fracture risk are lower among multiparous women even at older ages. These findings suggest that hormone replacement therapy can be delayed until 65 years of age for multiparous women but should be initiated at the beginning of menopause for nulliparous women.

Association between breast cancer and bone mineral density: the Dubbo Osteoporosis Epidemiology Study

BACKGROUND

The association between bone mineral density and breast cancer was investigated in a nested case-control study, involving 30 breast cancer cases and 120 controls, aged 68+/-6 (mean +/-S.D.) years, as part of the Dubbo Osteoporosis Epidemiology Study (Australia).

METHODS

Bone mineral density (BMD, g/cm(2)) at the femoral neck and lumbar spine was measured by dual energy X-ray absorptiometry. Anthropometric data and reproductive history were collected by direct interview using a structured questionnaire.

RESULTS

In univariate conditional logistic regression analysis, lower age at menarche, longer overall duration of lifetime ovulation and higher bone density were associated with higher risk of breast cancer. Among the breast cancer cases, 20% of subjects had lumbar spine BMD greater than 1.20 g/cm(2) (or 2.5 S.D. above the mean) compared with less than 1% of the controls. After adjusting for the effects of duration of lifetime ovulation and body mass index, each 0.1 g/cm(2) increase in lumbar spine and femoral neck BMD was associated with a 2.1-fold (95% CI: 1.3-3.4) and 1.5-fold (1.0-2.4) respectively, higher risk of breast cancer. Further adjustment for age at menarche, hormone replacement therapy, and parity did not alter the result. Thus, postmenopausal BMD, which is affected by lifetime exposure to estrogen, is also related to risk of breast cancer. Importantly, it is estimated that estrogen therapy in osteoporotic women, even if raising the risk of breast cancer by 70% as suggested by some studies, would not elevate their risk to the level experienced by their non-osteoporotic counterparts.

CONCLUSION

While the mechanism of this relationship remains to be explored, these data support the concept that lifetime exposure to estrogen is an indicator of risk of both breast cancer and osteoporosis. However, the use of estrogen in osteoporosis treatment would not elevate the risk of breast cancer in osteoporotic women up to the level experienced by their non-osteoporotic counterparts.

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.

HRT and cancer risk: separating fact from fiction

INTRODUCTION AND METHODS

The benefits of hormone replacement therapy (HRT) in postmenopausal women are well known including control of vasomotor symptoms and long-term benefits on the cardiovascular, skeletal and central nervous systems. However, some studies have reported a link between long-term HRT use and cancer. This paper reviews some of the data related to HRT and major gynaecological cancers.

RESULTS

Appropriate HRT regimens can reduce the risk of endometrial hyperplasia in non-hysterectomised women and can reduce the incidence of colorectal cancer. There is no consensus on a link between HRT and ovarian cancer, and the data relating to HRT and breast cancer presents differing risk analyses. However, it is generally accepted that HRT taken for 5 years or less does not increase the risk of breast cancer. When HRT is taken for 10 years or more, the relative risk of being diagnosed with breast cancer is 1.46. Individual risk must be weighed against the benefits offered by HRT, especially in terms of the long-term beneficial effects on the cardiovascular, skeletal and central nervous systems. Whilst one in 8-12 women may contract breast cancer in the western world, one in 3 women over 65 will have cardiovascular disease and 30-50% of postmenopausal women will have osteoporosis.

CONCLUSION

Fear of cancer is one of the main reasons why women object to HRT. Physicians must be able to counteract this fear with fact, and counsel patients on their individual risk, as well as putting any cancer risk into perspective with other long-term benefits.

Screening for cardiovascular disease. Concepts, conflicts, and consensus

CVD in the United States is prevalent, costly, and disabling. Wherever in the arterial tree atherosclerosis occurs, the process appears to begin in youth, to develop under the influence of the same risk factors, and to be amenable to the same interventions. The relationship between CVD and its associated risk factors is continuous, is graded, and extends below thresholds previously defined as normal. This observation, in turn, is based on an appreciation that in our society, the gap between normal and optimal can be considerable. CVD is a multifactorial process, often related to modifiable lifestyle choices; we focus on any single risk factor to the exclusion of others puts patients in danger. Because risk factors rarely occur in isolation, risk assessment must be as multifactorial as the underlying disease process. By understanding differences between risk factors in terms of the impact of their modification on the underlying disease, targeted interventions become possible that are tailored to the likelihood of an individual patient acquiring CVD. To change the overall prevalence of an epidemic disease such as CVD, however, such a high-risk approach must be applied in concert with a population strategy that seeks to effect smaller degrees of change in the large segment of society that may be at only moderate risk but--because of their great numbers--bears most of the morbidity and mortality of CVD. Finally, despite the remarkable progress that has been made in our understanding of the pathophysiology of CVD and the effectiveness of risk factor modification, significant gaps remain between knowledge and behavior. Fewer than 50% of diabetics are even aware that they have the disease. Only a third of those whose lipid levels qualify them for treatment receive intervention of any kind, including dietary advice. Only 27% of hypertensives have their blood pressure adequately controlled. The potential impact of more vigorous screening practices in the primary care setting on the health of individuals and communities cannot be overstated.

Estrogen replacement therapy in women with a history of proliferative breast disease

BACKGROUND

Little information is available regarding the invasive breast carcinoma risk associated with estrogen replacement therapy (ERT) in women with histories of histologically defined breast lesions.

METHODS

A retrospective cohort study of a consecutive series of women who underwent breast biopsies that proved to be benign between 1952-1978 was conducted. Follow-up data were obtained for 9494 women (87.6% of women eligible for follow-up). To investigate the effect of ERT on invasive breast carcinoma risk, the analysis was restricted to women with premenopausal breast disease whose follow-up extended through menopause and who did not develop premenopausal breast carcinoma. Relative risks were calculated with respect to women who took ERT but whose benign breast biopsies had neither atypical hyperplasia (AH), complex fibroadenoma (CFA), nor proliferative disease without atypia (PDWA).

RESULTS

During 190,845 woman-years of follow-up there were 444 confirmed cases of invasive breast carcinoma in the entire cohort. Women with a history of AH had relative risks of invasive breast carcinoma of 2.87 (95% confidence interval [95% CI], 1.3-6.3) and 2.53 (95% CI, 1.0-6.3) if they did or did not take ERT, respectively. For women with a history of CFA these risks were 1.57 (95% CI, 0.72-3.4) and 1.46 (95% CI, 0.53-4.0), respectively, whereas for women with a history of PDWA they were 1.37 (95% CI, 0.88-2.1) and 1.13 (95% CI, 0.69-1.9), respectively.

CONCLUSIONS

ERT does not significantly elevate the risk of invasive breast carcinoma in women with previous histologically defined benign breast disease. Therefore, ERT is not contraindicated in these women.

Postmenopausal estrogen use and invasive versus in situ breast cancer risk

To examine the effect of cancer histopathology on the relationship between estrogen-replacement therapy (ERT) use and breast cancer risk, we performed a case-control study of 109 postmenopausal women 45 years or older with in situ or invasive breast cancer matched to 545 controls. When in situ and invasive tumors were combined, the overall odds ratio (OR) describing the association between ERT use and breast cancer risk was not statistically significantly elevated (adjusted OR = 1.48, 95% confidence interval [CI] = 0.89-2.47). When the analyses were confined to women with invasive disease, risk estimates were uniformly higher (adjusted OR = 1.85, 95% CI = 1.00-3.45). In contrast, the overall estimate for the relationship between ERT use and in situ breast cancer was close to 1 (adjusted OR = 1.08, 95% CI = 0.42-2.77). The positive association between ERT use and invasive breast cancer we observed, and the lack of association in women with in situ disease, may represent a distinct biological difference or may be related to the small sample size of our study.

Hormone replacement therapy, heart disease, and other considerations

Multiple observational studies suggest a marked reduction in risk of coronary heart disease (CHD) associated with postmenopausal estrogen use. A new meta-analysis presented here extends these results to estrogen plus progestin regimens. Although the findings from observational studies are strong and consistent, and there are several plausible mechanisms by which estrogen might reduce risk for CHD, most of the known biases would tend to exaggerate estrogen's benefit. Further, estrogen therapy clearly increases risk for endometrial hyperplasia and cancer, venous thromboembolic events and gallbladder disease, and long-term use probably also increases the risk of breast cancer. Therefore, until findings from randomized trials confirm and quantitate the benefit of estrogen therapy for prevention of CHD, we believe it should not be recommended to all postmenopausal women.

Breast cancer and hormone replacement therapy: collaborative reanalysis of data from 51 epidemiological studies of 52,705 women with breast cancer and 108,411 women without breast cancer. Collaborative Group on Hormonal Factors in Breast Cancer

BACKGROUND

The Collaborative Group on Hormonal Factors in Breast Cancer has brought together and reanalysed about 90% of the worldwide epidemiological evidence on the relation between risk of breast cancer and use of hormone replacement therapy (HRT).

METHODS

Individual data on 52,705 women with breast cancer and 108,411 women without breast cancer from 51 studies in 21 countries were collected, checked, and analysed centrally. The main analyses are based on 53,865 postmenopausal women with a known age at menopause, of whom 17,830 (33%) had used HRT at some time. The median age at first use was 48 years, and 34% of ever-users had used HRT for 5 years or longer. Estimates of the relative risk of breast cancer associated with the use of HRT were obtained after stratification of all analyses by study, age at diagnosis, time since menopause, body-mass index, parity, and the age a woman was when her first child was born.

FINDINGS

Among current users of HRT or those who ceased use 1-4 years previously, the relative risk of having breast cancer diagnosed increased by a factor of 1.023 (95% CI 1.011-1.036; 2p=0.0002) for each year of use; the relative risk was 1.35 (1.21-1.49; 2p=0.00001) for women who had used HRT for 5 years or longer (average duration of use in this group 11 years). This increase is comparable with the effect on breast cancer of delaying menopause, since among never-users of HRT the relative risk of breast cancer increases by a factor of 1.028 (95% CI 1.021-1.034) for each year older at menopause. 5 or more years after cessation of HRT use, there was no significant excess of breast cancer overall or in relation to duration of use. These main findings did not vary between individual studies. Of the many factors examined that might affect the relation between breast cancer risk and use of HRT, only a woman's weight and body-mass index had a material effect: the increase in the relative risk of breast cancer associated with long durations of use in current and recent users was greater for women of lower than of higher weight or body-mass index. There was no marked variation in the results according to hormonal type or dose but little information was available about long durations of use of any specific preparation. Cancers diagnosed in women who had ever used HRT tended to be less advanced clinically than those diagnosed in never-users. In North America and Europe the cumulative incidence of breast cancer between the ages of 50 and 70 in never-users of HRT is about 45 per 1000 women. The cumulative excess numbers of breast cancers diagnosed between these ages per 1000 women who began use of HRT at age 50 and used it for 5, 10, and 15 years, respectively, are estimated to be 2 (95% CI 1-3), 6 (3-9), and 12 (5-20). Whether HRT affects mortality from breast cancer is not known.

INTERPRETATION

The risk of having breast cancer diagnosed is increased in women using HRT and increases with increasing duration of use. This effect is reduced after cessation of use of HRT and has largely, if not wholly, disappeared after about 5 years. These findings should be considered in the context of the benefits and other risks associated with the use of HRT.

Mammographic density in women on postmenopausal hormone replacement therapy

BACKGROUND

Studies have suggested that mammographic density and pattern are affected by hormone replacement therapy (HRT) and may influence breast diagnosis. Because 40% of breast cancers diagnosed at our center are mammographically detected while still clinically occult, mammographic sensitivity is crucial. For this reason we studied the effect of HRT on mammographic density.

METHODS

During a period of 18 months we studied consecutive women older than 54 years attending for breast screening. We recorded HRT use and dosing regimes. A breast density score (BDS) was developed and applied to all mammograms.

RESULTS

Mammograms of 148 HRT users were compared with those of 158 nonusers. HRT users had a significantly higher mean density score (4.7 versus 3.4; p < 0.001). Only 11% of non-HRT users had high scores compared with 37% among HRT users (p < 0.001). The significant difference remained when women were stratified by age. Duration of HRT (longer or shorter than 5 years) did not affect density scores.

CONCLUSIONS

HRT is associated with a significant increase in breast density. In turn, density and mammographic sensitivity are related. The possibility that increased breast density will hamper mammographic diagnosis of clinically occult cancers is worrisome.

Hormone replacement therapy and risk for breast cancer

Because breast cancer will develop in one of every nine American women, even a small increase in risk associated with a widespread exposure is of substantial public health concern. Although most studies have not found ever use of estrogens to be a risk factor for breast cancer, it is not yet resolved whether current or long-term users experience some increase in risk. Given the fact that the indications for menopausal estrogen use have changed substantially over time, from short-term use for the relief of menopausal symptoms to long-term use for lifetime reduction of conditions such as cardiovascular disease and osteoporosis, it is imperative that the effects of long-term estrogen replacement on the risk for breast cancer be resolved. These studies are not without associated methodologic difficulties, with the ultimate interpretation of the association possibly dependent on the results of controlled clinical trials. Although such investigations are currently underway, the results will not be available for many years. To address more immediate concerns, continued emphasis should be placed on well-designed case-control and cohort studies. For the results to be reliable, attention must be directed to the effects of selection, recall and surveillance biases, confounding factors, detailed exposure relationships, subgroup variations, and disease associations. In addition, given the increasing trend for estrogens to be prescribed in combination with progestogens, the effects on breast tissue of this combined therapy merit immediate attention.

Estrogen replacement therapy in women with prior diagnosis and treatment for breast cancer

We followed 49 women who underwent a minimum of 2 years estrogen replacement therapy (ERT) after diagnosis and treatment for localized breast cancer. Forty-three women were treated with oral ERT. In this group, the median age at the time of cancer diagnosis was 46 years (range 26 to 66 years), and ERT was begun a median of 84 months after diagnosis (range 0 to 286 months). The patients were followed for a median of 144 months after cancer diagnosis (range 46 to 324 months), and the median duration of ERT was 31 months (range 24 to 142 months). For six women, ERT was administered as a vaginal cream application. In this group, the median age at time of cancer diagnosis was 46 years (range 38 to 57 years), and ERT was begun a median of 49 months after diagnosis (range 24 to 61 months). The patients were followed for a median of 95 months after cancer diagnosis (range 72 to 154 months), and the median duration of ERT was 47 months (range 27 to 80 months). One patient experienced disease recurrence; she had received surgery for a stage I, estrogen receptor (ER)-positive lesion. The patient began ERT 30 months after cancer diagnosis and developed a recurrent ER-negative tumor 56 months after initiation of ERT. She remained alive without evidence of disease for 10 years since initial diagnosis of breast cancer. Despite the inherent limitations of retrospective experiential data and the need for prospective, randomized trials to assess the safety of ERT, the present observations suggest that ERT does not appear to have a pronounced adverse effect on cancer outcome. Nevertheless, until appropriate clinical trials determine that ERT is safe, caution is needed.

HRT and breast cancer risk, what to advise?

Breast cancer is the major malignancy among women in Western countries and constitutes approximately 25% of all female cancers. There is epidemiological evidence that reproductive factors and reproductive hormones are important for incidence as well as individual risk. Unfortunately the potential public health benefits of HRT have not been realised largely because of the fear of breast cancer. Epidemiological studies are conflicting but several reviews do suggest a moderately increased risk of breast cancer in long term current users of HRT. In clinical practice beneficial effects of long term HRT on women's health must be weighed against this background. The risk for adverse effects during a treatment during a period say 6-8 years is known to be very low. There is no indication for progestogen addition in women without a uterus. In most women with risk factors of osteoporosis, benefits from long term HRT apparently outweighs other possible risks. Individual asymptomatic women without any specific risk factors may well receive HRT after individual information but general recommendations for treatment of all asymptomatic women are currently not justified.

Estrogen replacement therapy and risk of fatal breast cancer in a prospective cohort of postmenopausal women in the United States

This study examines the relationship between fatal breast cancer and use of estrogen replacement therapy (ERT) among women in a large prospective study in the United States. After nine years of follow-up, 1,469 breast cancer deaths were observed in a cohort of 422,373 postmenopausal women who were cancer free at study entry and who supplied information on estrogen use. Results from Cox proportional hazards modeling, adjusted for 11 other potential risk factors, showed that ever-use of ERT was associated with a significantly decreased risk of fatal breast cancer (rate ratio [RR] = 0.84, 95 percent confidence interval [CI] = 0.75-0.94). There was a moderate trend (P = 0.07) of decreasing risk with younger age at first use of ERT. This decreased risk was most pronounced in women who experienced natural menopause before the age of 40 years (RR = 0.59, CI = 0.40-0.87). There was no discernible trend of increasing risk with duration of use in estrogen users at baseline or former users, nor was there any trend in years since last use in former users. The relationship between ERT and breast cancer mortality differed by age at menarche and by a self-reported history of breast cysts. No increased risk of fatal breast cancer with ERT was observed with estrogen use status (baseline/former), age at first use, duration of use, or years since last use. These findings suggest that ever-use of ERT is associated with a 16 percent decreased risk of fatal breast cancer.

Cancer risk in women receiving estrogen-progestin replacement therapy

OBJECTIVES AND METHODS

The epidemiological literature was reviewed in order to evaluate the relationship between hormone replacement therapy and risk of cancer in the breast and reproductive organs.

RESULTS

For breast cancer, there is no evidence of an overall increase in the risk. According to several studies, but not all, the duration of intake seems to affect the risk. Many years of intake of both estradiol compounds and conjugated estrogens can be assumed to increase the risk of breast cancer 1.5-2-fold. The addition of progestins does not seem to alter (reduce) the duration-risk relationship. The magnitude of risk increase is likely to be small and may be explained partly by methodological problems, or by differences in study populations. The prognosis in patients with HRT-related breast cancer seems to be more favourable than for non-exposed breast cancer patients. Because of the importance of the issue, and inconsistencies in results, further research is urgent. Especially, there is an urgent need to define sub-groups of women who would be susceptible to an adverse influence of HRT. Regarding endometrial cancer, a duration-dependent strong risk relationship with long-term intake of estrogens only is established. The level of risk increase is about 10-fold after 10 or more years of intake, a risk relationship that seems to decrease after discontinuation of treatment. Added progestins for at least 10 days per cycle can reduce or eliminate the risk increase. Tumors occurring after estrogen replacement have favourable biological characteristics. Future research will be needed to define the long-term safety of various progestin regimens. Ovarian cancer risk does not seem to be affected by HRT. Available data are inconsistent and contradictory. Due to the pronounced protective effect of oral contraceptives, further research is needed to measure effects of estrogen-progestin combined regimens. Cervical cancer risk has not been shown to be affected by HRT.

CONCLUSIONS

It is concluded that hormone replacement therapy, with estrogens alone or estrogens combined with progestins, may have important effects on the risk of cancer, particularly in the breast and endometrium. Therefore, when making a risk-benefit assessment of long-term HRT, possible risk relationships should be considered.

Hormone therapy in the menopause and breast cancer risk--a review

OBJECTIVES

To evaluate the association between use of hormones in the menopause and breast cancer risk.

METHODS

A qualitative review of reports published between 1970 and 1995.

RESULTS

The risk of breast cancer starts to increase after 5 or more years of hormone use and remains elevated while taking hormones. Use for 10 or more years may be associated with a 30-80% increase in risk. From 2 to 5 years after stopping taking hormones, the risk seems to return to unity. There is no difference in risk between different types of oestrogens and the addition of progestins does not lower the risk.

CONCLUSIONS

Short term use (less than 5 years) seems safe with respect to breast cancer risk, while longer durations of use may be associated with a small, but significant increase in risk.

Does hormone replacement therapy increase the risk of breast cancer?

The data contained in the literature about breast cancer risk and hormone replacement therapy is reviewed. Many studies with different methodologies have been published. Analysis of classical papers or of meta-analysis do not support the view that short-term use of hormone replacement therapy significantly increases the risk of breast cancer. In some clinical situations such as family history of breast cancer, high dose estrogens and especially in the case of long term treatment over 10 years, risk of cancer could be increased and requires a specific clinical management. Despite of the absence of double blind placebo-controlled trial, there is no strong data available to oppose the use of estrogen replacement therapy because of an hypothetic increased risk of breast cancer. Using a low posology for less than 5 years in correctly managed women is a safe attitude.

Hormone replacement treatment and breast cancer risk: a cooperative Italian study

The relationship between hormone replacement treatment (HRT) and breast cancer risk was analysed using data from a case-control study conducted between June 1991 and February 1994 in six Italian centres on 2569 patients aged below 75 with histologically confirmed breast cancer and 2588 controls admitted to hospital for a wide spectrum of acute, non-neoplastic, non hormone-related diseases. Ever HRT use was reported by 7.5% of cases and 7.5% of controls, corresponding to a multivariate odds ratio (OR) of 1.2 [95% confidence interval (CI), 0.9-1.5]. The risk increased with increasing duration of use: the ORs were 1.0 for use lasting less than 1 year, 1.3 for 1-4 years and 1.5 for 5 years or more. There was no clear pattern of risk with reference to time since starting use, but the OR was significantly elevated (OR = 2.0, 95% CI 1.3-2.9) for women who had stopped HRT within the last 10 years. No association was observed in those who had stopped HRT more than 10 years ago (OR = 1.0). The increased OR for women who had stopped HRT within the last 10 years was consistent across strata of identified covariates, and was significantly related to duration of use. This study confirms the absence of a strong association between HRT and breast cancer risk, although the risk estimate was above unity for women who had used HRT for 5 years or longer. However, the risk was significantly elevated in the short to medium term after use, particularly for long-term use. This short-term increased risk is consistent with an effect of HRT on one of the later stages of the process of breast carcinogenesis. The flattening of risk with increasing time since stopping, and hence the absence of a long-term cumulative excess in breast cancer risk after stopping HRT exposure, has relevant implications on individual risk assessment and public health.

The use of estrogens and progestins and the risk of breast cancer in postmenopausal women

BACKGROUND

The effect of adding progestins to estrogen therapy on the risk of breast cancer in postmenopausal women is controversial.

METHODS

To quantify the relation between the use of hormones and the risk of breast cancer in postmenopausal women, we extended our follow-up of the participants in the Nurses' Health Study to 1992. The women were asked to complete questionnaires every two years to update information on their menopausal status, use of estrogen and progestin preparations, and any diagnosis of breast cancer. During 725,550 person-years of follow-up, we documented 1935 cases of newly diagnosed invasive breast cancer.

RESULTS

The risk of breast cancer was significantly increased among women who were currently using estrogen alone (relative risk, 1.32; 95 percent confidence interval, 1.14 to 1.54) or estrogen plus progestin (relative risk, 1.41; 95 percent confidence interval, 1.15 to 1.74), as compared with postmenopausal women who had never used hormones. Women currently taking hormones who had used such therapy for 5 to 9 years had an adjusted relative risk of breast cancer of 1.46 (95 percent confidence interval, 1.22 to 1.74), as did those currently using hormones who had done so for a total of 10 or more years (relative risk, 1.46; 95 percent confidence interval, 1.20 to 1.76). The increased risk of breast cancer associated with five or more years of postmenopausal hormone therapy was greater among older women (relative risk for women 60 to 64 years old, 1.71; 95 percent confidence interval, 1.34 to 2.18). The relative risk of death due to breast cancer was 1.45 (95 percent confidence interval, 1.01 to 2.09) among women who had taken estrogen for five or more years.

CONCLUSIONS

The addition of progestins to estrogen therapy does not reduce the risk of breast cancer among postmenopausal women. The substantial increase in the risk of breast cancer among older women who take hormones suggests that the trade-offs between risks and benefits should be carefully assessed.

Clinical pharmacology of estrogens: cardiovascular actions and cardioprotective benefits of replacement therapy in postmenopausal women

The use of estrogens in postmenopausal women has been the subject of much controversy regarding hormone formulation, dosage, use in combination with progestins, duration of treatment, and contraindications. Estrogens have been prescribed to relieve menopausal symptoms for more than three decades. The hormones reduce the gynecologic and psychologic changes associated with menopause while inhibiting bone resorption and possibly reducing the risk of cardiovascular disease. Their use however has been complicated by an increased risk of endometrial cancer and possibly breast cancer. The use of estrogens as cardioprotective agents is discussed and the clinical experiences and the possible mechanisms of action are reviewed. The clinical pharmacology of estrogens and the various formulations that are available as monotherapy or in combination with progestins will also be reviewed.

Clinical pharmacology of estrogens: cardiovascular actions and cardioprotective benefits of replacement therapy in postmenopausal women

The use of estrogens in postmenopausal women has been the subject of much controversy regarding hormone formulation, dosage, use in combination with progestins, duration of treatment, and contraindications. Estrogens have been prescribed to relieve menopausal symptoms for more than three decades. The hormones reduce the gynecologic and psychologic changes associated with menopause while inhibiting bone resorption and possibly reducing the risk of cardiovascular disease. Their use however has been complicated by an increased risk of endometrial cancer and possibly breast cancer. The use of estrogens as cardioprotective agents is discussed and the clinical experiences and the possible mechanisms of action are reviewed. The clinical pharmacology of estrogens and the various formulations that are available as monotherapy or in combination with progestins will also be reviewed.

Menopausal estrogen and estrogen-progestin replacement therapy and risk of breast cancer (United States)

This study examines the relationship between menopausal estrogen and estrogen-progestin replacement therapy and risk of breast cancer, focusing on whether associations differ according to whether the tumors are in situ or invasive. Data are from a prospective study conducted 1980-89 on 49,017 selected participants in the Breast Cancer Detection Demonstration Project, a five-year screening program conducted between 1973 and 1980 in the United States. Overall, the rate ratio for estrogen-only use compared with no-hormone use was 1.0, and that for the estrogen-progestin combination was 1.2 (95 percent confidence interval [CI] = 1.0-1.6). However, the associations differed according to whether the tumors were in situ or invasive. The rate ratios of in situ breast cancer associated with use of estrogens alone and the combination regimen were 1.4 (CI = 1.0-2.0) and 2.3 (CI = 1.3-3.9), respectively. Duration of estrogen-only use also was associated with risk of in situ tumors, with users for 10 or more years at twice the risk of nonusers (P-value for trend test = 0.02). Duration of use was not associated with risk of invasive cancer. Our results are consistent with the hypothesis that hormone replacement therapy is related to earlier-stage breast cancer; however, the possibility that the results reflect increased breast cancer surveillance among those taking hormones cannot be ruled out.