Does menopausal hormone replacement therapy interact with known factors to increase risk of breast cancer?

Cardiovascular Disease in Women and the Role of Hormone Replacement Therapy

Cardiovascular disease (CVD) is the leading cause of death in women and manifests more severely and at a later stage in life compared to men. The low estrogen levels during menopause are linked to an increased CVD risk. This association has promoted research regarding the role of hormone replacement therapy (HRT) in reducing the symptoms and diseases related to menopause, including CVD. This review article aims to discuss the biological changes associated with menopause and their impact on CVD. It also examines the effects of HRT in women with comorbidities related to CVD, its indications, risks, and contraindications.

Use of exogenous hormones in those at increased risk for breast cancer: contraceptive and menopausal hormones in gene carriers and other high-risk patients

IMPORTANCE AND OBJECTIVE

Addressing the hormonal needs of individuals at increased risk of breast cancer (BC) can be a challenge. Observational, prospective, and case-control data support the safety of hormonal contraception in women, often with the added benefits of ovarian and endometrial cancer risk reduction. The majority of data on menopausal hormone therapy (HT) in the highest-risk patients comes from studies of patients with pathogenic variants in BRCA1 and BRCA2 who undergo early surgical menopause. The benefits of risk-reducing salpingo-oophorectomy are not minimized by HT, whereas its use mitigates accelerated osteoporosis and cardiovascular disease. In other patients at increased risk, such as with family history, studies have shown little risk with significant benefit.

METHODS

We review evidence to help women's health practitioners aid patients in making choices. The paper is divided into four parts: 1, contraception in the very high-risk patient (ie, with a highly penetrant BC predisposition gene); 2, contraception in other patients at increased risk; 3, menopausal HT in the gene carrier; and 4, HT in other high-risk patients.

DISCUSSION AND CONCLUSION

Women at increased risk for BC both early and later in life should be offered reassurance around the use of premenopausal and postmenopausal hormone therapies. The absolute risks associated with these therapies are low, even in the very high-risk patient, and the benefits are often substantial. Shared decision making is key in presenting options, and knowledge of the data in this area is fundamental to these discussions.

Estrogen-progestin use and breast cancer characteristics in lean and overweight postmenopausal women

PURPOSE

Breast cancer associated with estrogen-progestin (EP) therapy may have more favorable characteristics than cancer in never users, but results are conflicting. It is not well known either whether Body Mass Index (BMI) modifies this association. We investigated breast cancer characteristics in EP users for lean (BMI < 25 kg/m²) and overweight women (BMI ≥ 25 kg/m²).

METHODS

The Icelandic Cancer Detection Clinic cohort, with information on breast cancer risk factors for 90% of Icelandic women, was linked with the population-based Icelandic Cancer Registry. A total of 781 women with invasive breast cancer diagnosed 51 years or older were matched with 7761 controls from the cohort. Conditional logistic regression was used for estimating adjusted odds ratios (OR) and 95% confidence intervals (CI) according to tumor characteristics, stratified by BMI. Polytomous logistic regression was applied in a case-only analysis for testing whether the risk associated with EP use differed according to tumor characteristics.

RESULTS

Ever EP users had a twofold higher risk of breast cancer compared with never users (OR 2.05, 95% CI 1.71-2.45). In lean women, EP use was significantly less likely to be associated with grade 2 or 3 tumors than grade 1 tumors, contrary to overweight women for whom risk was increased irrespective of grade. EP use in overweight women was associated with a higher risk of lobular than ductal cancer (OR 2.75, 95% CI 1.29-5.87).

CONCLUSION

Among lean EP users, tumor characteristics were more favorable than among never users. This effect was not observed for overweight women.

Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program

Background

Breast cancer comprises several molecular subtypes with different prognoses and possibly different etiology. Reproductive and hormonal factors are associated with breast cancer overall, and with luminal subtypes, but the associations with other subtypes are unclear. We used data from a national screening program to conduct a large nested case-control study.

Methods

We conducted a nested case-control study on participants in the Norwegian Breast Cancer Screening Program in 2006 − 2014. There was information on estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) for 4748 cases of breast cancer. Breast cancer subtypes were defined as luminal A-like (ER+ PR+ HER2-), luminal B-like (ER+ PR- HER2- or ER+ PR+/PR-HER2+), HER2-positive (ER- PR- HER2+) and triple-negative (ER- PR- HER2-). Conditional logistic regression was used to estimate odds ratios (ORs) of breast cancer associated with age at first birth, number of pregnancies, oral contraceptive use, intrauterine devices and menopausal hormone therapy. Analyses were adjusted for age, body mass index, education, age at menarche, number of pregnancies and menopausal status.

Results

Number of pregnancies was inversely associated with relative risk of luminal-like breast cancers (p-trend ≤0.02), and although not statistically significant, with HER2-positive (OR = 0.60, 95% CI 0.31–1.19) and triple-negative cancer (OR = 0.70, 95% CI 0.41–1.21). Women who had ≥4 pregnancies were at >40% lower risk of luminal-like and HER2-positive cancers than women who had never been pregnant. However, there was a larger discrepancy between tumor subtypes with menopausal hormone use. Women who used estrogen and progesterone therapy (EPT) had almost threefold increased risk of luminal A-like cancer (OR = 2.92, 95% CI 2.36–3.62) compared to never-users, but were not at elevated risk of HER2-positive (OR = 0.88, 95% CI 0.33–2.30) or triple-negative (OR = 0.92, 95% CI 0.43 − 1.98) subtypes.

Conclusions

Reproductive factors were to some extent associated with all subtypes; the strongest trends were with luminal-like subtypes. Hormone therapy use was strongly associated with risk of luminal-like breast cancer, and less so with risk of HER2-positive or triple-negative cancer. There are clearly some, but possibly limited, etiologic differences between subtypes, with the greatest contrast between luminal A-like and triple-negative subtypes.

Trial registration

Not applicable.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

IMPACT

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

Hormone Therapy and its Effect on the Prognosis in Breast Cancer Patients

Introduction: Use of hormone therapy (HT) has declined dramatically in recent years. Some studies have reported that HT use before a diagnosis of breast cancer (BC) may be a prognostic factor in postmenopausal patients. This study aimed to examine the prognostic relevance of HT use before BC diagnosis. Methods: Four BC cohort studies in Germany were pooled, and 4492 postmenopausal patients with HT use data were identified. Patient data and tumor characteristics were compared between users and nonusers, along with overall survival (OS), distant metastasis-free survival (DMFS), and local recurrence-free survival (LRFS). Cox proportional hazards models were stratified by study center and adjusted for age at diagnosis, tumor stage, grading, nodal status, and hormone receptors. Results: Women with HT use before the diagnosis of BC were more likely to have a lower tumor stage, to be estrogen receptor-negative, and to have a lower grading. With regard to prognosis there were effects seen for OS, DMFS and LRFS, specifically in the subgroup of women with a positive hormone receptor. In these subgroups, BC patients had a better prognosis with previous HT use. Conclusions: HT use before a diagnosis of BC is associated with a more favorable prognosis in women with a positive hormone receptor status. It may be recommended that the prognostic factor HT should be documented and analyzed as a confounder for prognosis in studies of postmenopausal hormone-responsive breast cancers.

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

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

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

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

Fatal breast cancer risk in relation to use of unopposed estrogen and combined hormone therapy

Use of combined hormone therapy (CHT) is associated with increased breast cancer incidence, but it is unclear whether this translates into increased breast cancer mortality. To address this question, we conducted a population-based nested case-control study in Saskatchewan, Canada, where a population-based prescription drug database has existed since 1975. We evaluated fatal breast cancer risk in relation to recency and duration of use of CHT and unopposed estrogen hormone therapy (EHT). A total of 1,288 cases and 12,535 controls were included in the analyses. Exclusive use of EHT was not associated with fatal breast cancer risk, either overall or within categories of recency or duration [odds ratio (OR) for current vs. never use = 1.1; 95 % confidence interval (CI) 0.8-1.3]. Use of CHT (includes women who had also used EHT) was also not associated with fatal breast cancer risk (OR for current vs. never use = 0.9; 95 % CI 0.7-1.3), except for a suggestion of an increased risk with current long-term use. Consistent with prior studies, we observed no increased risk of fatal breast cancer associated with use of EHT. To date only a few studies have evaluated fatal breast cancer risk in relation to use of CHT, and collectively the results are inconsistent.

Interactions of hormone replacement therapy, body weight, and bilateral oophorectomy in breast cancer risk

PURPOSE

To examine potential modifying effects of body weight and bilateral oophorectomy on the association of hormone replacement therapy (HRT) with risk of breast cancer, overall and by subtypes according to status of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (Her2) among postmenopausal women.

EXPERIMENTAL DESIGN

This analysis included 2,510 postmenopausal white women recruited in the Nashville Breast Health Study, a population-based case-control study of breast cancer. Multivariable logistic regression was used to estimate ORs and 95% confidence intervals (CI) for associations between HRT use and risk of breast cancer overall and by subtypes, adjusted for age and education.

RESULTS

Among women with natural menopause and body mass index (BMI) < 25 kg/m(2), ever-use of HRT was associated with increased breast cancer risk (OR, 1.95; 95% CI, 1.32-2.88). Risk was elevated with duration of HRT use (P for trend = 0.002). Similar association patterns were found for ER(+), ER(+)PR(+), and luminal A cancer subtypes but not ER(-), ER(-)PR(-), and triple-negative cancer. In contrast, ever-HRT use in overweight women (BMI ≥ 25 kg/m(2)) showed no association with risk of breast cancer overall or by subtypes; interaction tests for modifying effect of BMI were statistically significant. Ever-HRT use was associated with decreased breast cancer risk (OR, 0.70; 95% CI, 0.38-1.31) among women with prior bilateral oophorectomy but elevated risk (OR, 1.45; 95% CI, 0.92-2.29) among those with hysterectomy without bilateral oophorectomy (P for interaction = 0.057). Similar associations were seen for virtually all breast cancer subtypes, although interaction tests were statistically significant for ER(+) and luminal A only.

CONCLUSION

Body weight and bilateral oophorectomy modify associations between HRT use and breast cancer risk, especially the risk of hormone receptor-positive tumors.

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

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

Menopausal hormone therapy and subsequent risk of specific invasive breast cancer subtypes in the California Teachers Study

BACKGROUND

Although it is well established that combined estrogen-progestin therapy (EPT) increases breast cancer risk, questions remain regarding the effect of different formulations of hormones, whether certain women are at particularly high risk, and whether risk varies by tumor subtype.

METHODS

We investigated hormone therapy (HT) use in relation to breast cancer risk in the California Teachers Study cohort; after a mean follow-up of 9.8 years, 2,857 invasive breast cancers were diagnosed.

RESULTS

Compared with women who had never used HT, women who reported 15 or more years of estrogen therapy (ET) use had a 19% greater risk of breast cancer (95% confidence interval, 1.03-1.37), whereas women using EPT for 15 or more years had an 83% greater risk (95% confidence interval, 1.48-2.26). Breast cancer risk was highest among women using continuous combined EPT regimens. Risks associated with EPT and ET use were increased with duration of HT use for women with a body mass index (BMI) of <29.9 kg/m(2) but not for women with BMI of >or=30 kg/m(2). Elevated risks associated with EPT and ET use were confined to tumors that were positive for both estrogen and progesterone receptors and those that were HER2+ but were slightly diminished for HER2- tumors.

CONCLUSIONS

Breast cancer risks increased with longer duration of ET and EPT use, and risks were highest for continuous-combined EPT use. Furthermore, risks varied by BMI and tumor subtype.

IMPACT

These findings underscore the need for personalized risk-benefit discussions with women contemplating HT use.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Is there a difference in the association between percent mammographic density and subtypes of breast cancer? Luminal A and triple-negative breast cancer

BACKGROUND

Mammographic density is a potentially modifiable risk factor for breast cancer. To what extent mammographic density is a predictor for both hormone receptor-positive and hormone receptor-negative tumors is unclear. Even less is known about whether mammographic density predicts subtypes of breast cancer defined by expression status of the three receptors: estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER-2).

METHODS

We estimated the association of percent mammographic density with subtypes of invasive breast cancer among 479 population-based female breast cancer patients and 376 control subjects ages 35 to 64 years. The expression status of ER, PR, and HER-2 was assessed using immunohistochemistry methods in a single laboratory. We considered ER+ or PR+ plus HER-2- tumors as luminal A breast cancer and ER-/PR-/HER-2- tumors as triple-negative breast cancer. We used unconditional logistic regression methods to estimate odd ratios (95% confidence intervals) for both case-control and case-case comparisons.

RESULTS

Mammographic density was associated with increased risk of both invasive breast cancer subtypes, luminal A and triple-negative, in the case-control analysis. Results from case-case comparisons yielded no differences between the two subtypes among all women combined or in analyses done separately by race (White versus African American women) or menopausal status (premenopausal versus postmenopausal women; all P values > 0.05).

CONCLUSIONS

Our results suggest that percent mammographic density is positively associated with both luminal A and triple-negative breast cancer.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

PURPOSE

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

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

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

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

OBJECTIVE

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Risk factors and hormone-receptor status: epidemiology, risk-prediction models and treatment implications for breast cancer

It is increasingly being recognized that breast cancer does not represent a single homogeneous disease; instead, the hormone-receptor status defines important clinical and etiologic differences. We review the epidemiologic data on differences in risk-factor associations by hormone-receptor status and highlight major trends in the literature. We discuss the development and evaluation of breast cancer risk models, with a focus on the Rosner and Colditz model, which can separately estimate the risk of hormone-receptor-positive and hormone-receptor-negative breast cancers. We also discuss the clinical implications of accounting for hormone-receptor status in breast cancer risk-prediction models.

Risk factors for hormone receptor-defined breast cancer in postmenopausal women

The effect of classic breast cancer risk factors on hormone receptor-defined breast cancer is not fully clarified. We explored these associations in a Swedish population-based study. Postmenopausal women ages 50 to 74 years, diagnosed with invasive breast cancer during 1993 to 1995, were compared with 3,065 age frequency-matched controls. We identified 332 estrogen receptor (ER-) and progesterone receptor (PR-) negative, 286 ER+PR-, 71 ER-PR+, 1,165 ER+PR+, and 789 tumors with unknown receptor status. Unconditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI). Women ages >or=30 years, compared with those ages 20 to 24 years at first birth, were at an increased risk of ER+PR+ tumors (OR, 1.5; 95% CI, 1.2-1.8) but not ER-PR- tumors (OR, 1.1; 95% CI, 0.8-1.6). Women who gained >or=30 kg in weight during adulthood had an approximately 3-fold increased relative risk of ER+PR+ tumors (OR, 2.7; 95% CI, 1.9-3.8), but no risk increase of ER-PR- tumors (OR, 1.0; 95% CI, 0.5-2.1), compared with women who gained <10 kg. Compared with never users, women who used menopausal estrogen-progestin therapy for at least 5 years were at increased risk of ER+PR+ tumors (OR, 3.0; 95% CI, 2.1-4.1) but not ER-PR- tumors (OR, 1.3; 95% CI, 0.7-2.5). In conclusion, other risk factors were similarly related to breast cancer regardless of receptor status, but high age at first birth, substantial weight gain in adult age, and use of menopausal estrogen-progestin therapy were more strongly related to receptor-positive breast cancer than receptor-negative breast cancer.

Hormone replacement therapy and breast cancer in former users of oral contraceptives—The Norwegian Women and Cancer study

Combined estrogen-progestin menopausal therapy (HRT) and combined estrogen-progestin contraceptives (OC) both increase breast cancer risk during current use and a few years after. We investigated risk of breast cancer in women who were users of HRT dependant on former history of OC use in a large, national population-based cohort study, the Norwegian Women and Cancer study (NOWAC). Exposure information was collected through postal questionnaires. Based on follow-up of 30,118 postmenopausal women by linkage to national registers of cancer, deaths, and emigration we revealed 540 incident breast cancer cases between 1996 and 2004. Compared to never users of either drugs current use of HRT gave a significant (p = 0.002) higher risk of breast cancer in former OC users, RR = 2.45 (95% CI 1.92-3.12), than among never users of OCs, RR = 1.67 (1.32-2.12). Relative risk of current use of HRT was similar for estrogen only and combinations with progestin added in ever users of OCs. The increased risk of breast cancer in current HRT users with a history of former OC use could have potential great impact on postmenopausal breast cancer risk as the proportion of postmenopausal women with former OC use will continue to increase.

Do breast cancer risk factors modify the association between hormone therapy and mammographic breast density? (United States)

OBJECTIVE

To evaluate whether the association between hormone therapy (HT) and breast density differs by levels of breast cancer risk factors.

METHODS

We evaluated 80,867 screening mammograms from 39,296 postmenopausal women from Washington State. We estimated odds ratios and 95% confidence intervals for dense breasts (Breast Imaging Reporting and Data System categories 3 "heterogeneously dense" and 4 "extremely dense") compared to fatty breasts (categories 1 "almost entirely fat" and 2 "scattered fibroglandular") among HT users compared to never users. We separately examined former HT use and current HT use by type (estrogen plus progestin therapy (EPT) and estrogen-only therapy (ET)). We stratified the associations by age, BMI, race, family history, and reproductive and menopausal factors.

RESULTS

Current EPT users had a 98% (1.87-2.09) greater odds of having dense breasts and current ET users had a 71% (1.56-1.87) greater odds compared to never users. Current HT users were more likely to have dense breasts if they were older, had more children, or younger at first birth compared to never users; these associations were stronger among EPT users than ET users.

CONCLUSIONS

HT, particularly EPT, may reduce protective effects of older age, parity, and younger age at first birth on mammographic density.

Relationship between established breast cancer risk factors and risk of seven different histologic types of invasive breast cancer

BACKGROUND

Important differences in the contributions of certain exposures to the risks of ductal versus lobular breast carcinomas have been observed, but few studies have evaluated the relationships between established breast cancer risk factors and other histologic types.

METHODS

Information on family history of cancer and reproductive, hormonal, anthropometric, and lifestyle characteristics were collected in a multicenter population-based case-control study consisting of 3,463 ductal, 274 lobular, 261 ductal-lobular, 91 medullary, 77 tubular, 70 comedo, and 61 mucinous invasive breast carcinoma cases (ages 35-64 years, newly diagnosed 1994-1998) and 4,682 controls. Associations between each of these histologic types and various exposures were evaluated using polytomous regression.

RESULTS

Heterogeneity in the risks of different histologic types of breast cancer was observed for three exposures: menopausal hormone use, body mass index (BMI), and alcohol consumption. Specifically, current use of unopposed estrogen was associated with a reduced risk of ductal carcinoma and increased risk of comedocarcinoma, and current use of estrogen and progestin was associated with elevated risks of ductal-lobular and tubular carcinomas. Among postmenopausal women, BMI was only inversely related to risk of ductal-lobular carcinoma, and alcohol use was only positively related to risk of lobular carcinoma.

CONCLUSIONS

Variations in the associations between known breast cancer risk factors and risk of different breast cancer histologies were observed. Although these findings require confirmation, and the analyses of some histologic groups were limited by small sample sizes, they provide some insight into the different etiologies of various histologic subtypes of breast cancer.

Interactions between body mass index and hormone therapy and postmenopausal breast cancer risk (United States)

OBJECTIVE

To assess interactions between use of estrogen plus progestin hormone therapy (EPHT) and body mass index (BMI) in relation to risks of different types of breast cancer, based on histology and hormone receptor status.

METHODS

We conducted a population-based case-control study that compared 975 postmenopausal breast cancer cases to 1,007 controls. Interactions between menopausal hormone therapy (HT) and BMI in relation to risk of different breast cancer types were evaluated using logistic regression.

RESULTS

Obese (BMI > or = 30.0 kg/m2) never users of HT had 1.7-fold to 2.3-fold elevated risks of ductal and ER+/PR+ tumors, respectively, compared to thinner women. BMI was not related to breast cancer risk among current HT users. Current EPHT users for > or = 5 years had 2.1 to 9.6-fold elevated risks of lobular and ER+/PR+ tumors compared to never users of HT regardless of BMI. Current EPHT users for > or = 5 years with a BMI < or = 24.9 kg/m2 also had a 2.6-fold elevated risk of ductal carcinoma. However, none of the interactions between BMI and HT use evaluated reached statistical significance.

CONCLUSIONS

While interactions between HT and BMI are well established, they appear to only be present among certain breast cancer types. Since obesity is related to breast cancer risk only among never users of HT, as HT use declines the relative impact of obesity on breast cancer incidence may grow.

Endogenous steroid hormone concentrations and risk of breast cancer: does the association vary by a woman's predicted breast cancer risk?

PURPOSE

To examine whether the associations of endogenous estrogens and testosterone with breast cancer risk differ between high- and low-risk women, as determined by the Gail model and the Rosner and Colditz model, and by family history of breast cancer.

METHODS

We conducted a prospective nested case-control study within the Nurses' Health Study. From 1989 or 1990 until June 2000, blood samples were collected, 418 breast cancer patient cases were identified, and two controls (total n = 817) were matched to each case. We classified women as high or low risk based on their family history of breast cancer, their 5-year Gail risk score, and their 5-year Rosner and Colditz risk score. Multivariate relative risks (RR) and 95% CI were calculated by unconditional logistic regression, adjusting for matching and breast cancer risk factors.

RESULTS

Estrone sulfate was statistically significantly associated with breast cancer risk among women with low (< 1.66%) and high (> or = 2.52%; 75th percentile) Gail predicted risk (fourth v first quartile RR = 3.6; 95% CI, 1.9 to 7.0; RR = 2.5; 95% CI, 1.2 to 5.1, respectively). Testosterone results were similar across strata of predicted risk, with two times the risk in the fourth (v first) quartile. Estradiol appeared more strongly associated with breast cancer in women with higher predicted risk (RR = 4.5; 95% CI, 2.1 to 9.5) compared with women with lower risk (RR = 2.1; 95% CI, 1.2 to 3.6), but differences were not statistically significant. Results were similar across predicted Rosner and Colditz risk scores.

CONCLUSION

These data suggest that higher levels of endogenous estrogens and testosterone are associated with increased breast cancer risk, regardless of predicted risk or family history of breast cancer.

Menopausal hormone therapy and other breast cancer risk factors in relation to the risk of different histological subtypes of breast cancer: a case-control study

Introduction

Breast cancers of different histology have different clinical and prognostic features. There are also indications of differences in aetiology. We therefore evaluated the risk of the three most common histological subtypes in relation to menopausal hormone therapy and other breast cancer risk factors.

Methods

We used a population-based case-control study of breast cancer to evaluate menopausal hormone therapy and other breast cancer risk factors for risk by histological subtype. Women aged 50 to 74 years, diagnosed with invasive ductal (n = 1,888), lobular (n = 308) or tubular (n = 93) breast cancer in Sweden in 1993 to 1995 were compared with 3,065 age-frequency matched controls randomly selected from the population. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for ductal, lobular, and tubular cancer.

Results

Women who had used medium potency estrogen alone were at increased risks of both ductal and lobular cancer. Medium potency estrogen-progestin was associated with increased risks for all subtypes, but the estimates for lobular and tubular cancer were higher compared with ductal cancer. We found OR 5.6 (95% CI 3.2–9.7) for lobular cancer, OR 6.5 (95% CI 2.8–14.9) for tubular cancer and OR 2.3 (95% CI 1.6–3.3) for ductal cancer with ≥5 years use of medium potency estrogen-progestin therapy. Low potency oral estrogen (mainly estriol) appeared to be associated with an increased risk for lobular cancer, but the association was strongest for short-term use. Reproductive and anthropometric factors, smoking, and past use of oral contraceptives were mostly similarly related to the risks of the three breast cancer subtypes. Recent alcohol consumption of > 10 g alcohol/day was associated with increased risk only for tubular cancer (OR 3.1, 95% CI 1.4–6.8).

Conclusion

Menopausal hormone therapy was associated with increased risks for breast cancer of both ductal and lobular subtype, and medium potency estrogen-progestin therapy was more strongly associated with lobular compared with ductal cancer. We also found medium potency estrogen-progestin therapy and alcohol to be strongly associated with tubular cancer. With some exceptions, most other risk factors seemed to be similarly associated with the three subtypes of breast cancer.

Gonadotropin-releasing hormone analogues added to adjuvant chemotherapy protect ovarian function and improve clinical outcomes in young women with early breast carcinoma

BACKGROUND

The objective of the current study was a retrospective evaluation of 100 consecutive premenopausal women with high-risk, early breast carcinoma who received a gonadotropin-releasing hormone (Gn-RH) analogue as ovarian protection during adjuvant chemotherapy.

METHODS

After surgery, patients received a Gn-RH analogue and adjuvant chemotherapy, which was tailored to their peculiar biologic features. The median patient age was 43 years (range, 27-50 yrs). Fifty-two women had positive estrogen receptor (ER) status, and 48 women had negative ER status. There were 64 women with Stage II breast carcinoma and 36 women with UICC Stage III breast carcinoma. All patients had their serum estradiol suppressed to values<40 pg/mL. The chemotherapy regimens administered included cyclophosphamide, methotrexate, and 5-fluorouracil (n=26 patients) and anthracycline-based regimens (n=74 patients, including 9 patients who had >10 positive axillary lymph nodes, who also received high-dose chemotherapy with autologous peripheral blood progenitor cell transplantation). Patients with positive c-erb-2 status also received a taxane. Eighty patients received radiation therapy. During therapy with the Gn-RH analogue, patients who had a positive ER status after chemotherapy received an aromatase inhibitor.

RESULTS

After a median follow-up of 75 months, normal menses were resumed by all patients younger than age 40 years and by 56% of patients older than age 40 years. Three pregnancies were observed that resulted in two normal deliveries and one voluntary abortion. The projected recurrence-free survival rates at 5 years and 10 years were 84% and 76%, respectively; and the projected overall survival rates at 5 years and 10 years were 96% and 91%, respectively.

CONCLUSIONS

The current data showed that, in premenopausal women with early breast carcinoma, the addition of a Gn-RH analogue to adjuvant therapy and temporary total estrogen suppression in patients with ER-positive disease was tolerated well, protected long-term ovarian function, and appeared to improve the expected clinical outcome.

Factors modifying the association between hormone-replacement therapy and breast cancer risk

OBJECTIVES

Hormone-replacement therapy (HRT) is an established risk factor for breast cancer. HRT users are different from non-users with respect to socio-economic and other characteristics. There may be women where the HRT-related risk could be modulated by other factors.

METHODS

We conducted a population-based case-control study with 688 breast cancer cases and 724 controls to characterize HRT users and to estimate odds ratios (OR) and 95% confidence intervals (CI) for HRT use and potentially risk modifying factors.

RESULTS

In women aged 50 years and older, 58% of controls and 61% of cases ever used HRT. Among women in natural menopause, HRT use for 10 years and more years was associated with an increased breast cancer risk (OR 1.79, 95% CI, 1.12-2.87), but not among women in surgical menopause (OR 0.61, 95% CI, 0.09-4.17). In the subgroup of women with a positive family history of breast cancer, each year of HRT use increased the risk by 1.22 (95% CI, 1.02-1.47). Another subgroup comprised women with at least 10 diagnostic mammograms (OR 4.04, 95% CI, 1.10-14.81 for using HRT 10 or more years).

CONCLUSIONS

Long-term HRT use was associated with a breast cancer risk in women with natural menopause. Our findings suggest that this risk may be increased in women with a positive family history of breast cancer and in women who received frequent diagnostic mammographic screens.

Previous oral contraceptive use and breast cancer risk according to hormone replacement therapy use among postmenopausal women

OBJECTIVE

To assess postmenopausal breast cancer risk in relation to particular patterns of oral contraceptive (OC) use according to hormone replacement therapy (HRT) exposure.

METHODS

Time-dependent Cox regression models were used to analyse information on postmenopausal women from a large-scale French cohort. Among a total of 68,670 women born between 1925 and 1950, 1405 primary invasive postmenopausal breast cancer cases were identified from 1992 to 2000.

RESULTS

A non-significant decrease in risk of around 10% was associated with ever OC use as compared to never OC use in postmenopausal women. No significant interaction was found between OC and HRT use on postmenopausal breast cancer risk. Breast cancer risk decreased significantly with increasing time since first OC use (test for trend: p=0.01); this was consistent after adjustment for duration of use or for time since last use.

CONCLUSION

No increase in breast cancer risk was associated with previous OC exposure among postmenopausal women, probably because the induction window had closed. Some women may develop breast cancer soon after exposure to OCs, leading to a deficit of cases of older women. Further investigation is therefore required to identify young women at high risk.

Reproductive factors and subtypes of breast cancer defined by hormone receptor and histology

Reproductive factors are associated with reduced risk of breast cancer, but less is known about whether there is differential protection against subtypes of breast cancer. Assuming reproductive factors act through hormonal mechanisms they should protect predominantly against cancers expressing oestrogen (ER) and progesterone (PR) receptors. We examined the effect of reproductive factors on subgroups of tumours defined by hormone receptor status as well as histology using data from the NIHCD Women's Contraceptive and Reproductive Experiences (CARE) Study, a multicenter case–control study of breast cancer. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) as measures of relative risk using multivariate unconditional logistic regression methods. Multiparity and early age at first birth were associated with reduced relative risk of ER + PR + tumours (P for trend=0.0001 and 0.01, respectively), but not of ER − PR − tumours (P for trend=0.27 and 0.85), whereas duration of breastfeeding was associated with lower relative risk of both receptor-positive (P for trend=0.0002) and receptor-negative tumours (P=0.0004). Our results were consistent across subgroups of women based on age and ethnicity. We found few significant differences by histologic subtype, although the strongest protective effect of multiparity was seen for mixed ductolobular tumours. Our results indicate that parity and age at first birth are associated with reduced risk of receptor-positive tumours only, while lactation is associated with reduced risk of both receptor-positive and -negative tumours. This suggests that parity and lactation act through different mechanisms. This study also suggests that reproductive factors have similar protective effects on breast tumours of lobular and ductal origin.

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.

Assessing the effectiveness of a mammography screening service

BACKGROUND

Trials have shown that mammography screening reduces mortality and probably decreases morbidity related to breast cancer.

METHODS

We assessed whether the major mammography service in Western Australia (BreastScreen WA) is likely to reduce mortality by comparing prognostic variables between screen-detected and other cases of breast cancer diagnosed in 1999. We assessed likely reductions in morbidity by comparing treatments received by these two groups. To confirm mortality and morbidity reduction, we also compared prognostic variables and treatments with targets. Information on demographic variables, tumour characteristics at presentation and treatments were collected from medical records for all incident cases of breast cancer in Western Australia in 1999. We matched cases with the Western Australian Cancer Registry records to determine which cases had been detected by BreastScreen WA.

RESULTS

BreastScreen WA achieved the targets for mortality reduction. Tumours detected by BreastScreen WA were smaller in size, less likely to have vascular invasion, of lower histological grade and were more likely to be ductal carcinoma in situ alone without invasive carcinoma. Oestrogen receptor status was more likely to be positive, the difference in progesterone status was not significant, and lymph node involvement tended to be lower. BreastScreen WA patients were treated more often with local therapy and less often with systemic therapy, and the proportion of patients treated with breast-conserving surgery was close to the target for minimizing morbidity in breast cancer.

CONCLUSION

Mammographic detection of breast cancer by BreastScreen WA is associated with reduced breast cancer morbidity and a more favourable prognosis.

An overview of menopausal oestrogen-progestin hormone therapy and breast cancer risk

Results from the Women's Health Initiative (WHI) trial support findings from observational studies that oestrogen–progestin therapy (EPT) use is associated with an increase in breast cancer risk. We conducted a meta-analysis using EPT-specific results from the Collaborative Group on Hormonal Factors in Breast Cancer (CGHFBC) pooled analysis and studies published since that report to obtain an overview of EPT use and breast cancer risk. We also assessed risk by histologic subtype of breast cancer, by schedule of the progestin component of EPT, and by recency of use. We estimate that overall, EPT results in a 7.6% increase in breast cancer risk per year of use. The risk was statistically significantly lower in US studies than in European studies – 5.2 vs 7.9%. There was a significantly higher risk for continuous-combined than for sequential EPT use in Scandinavian studies where much higher total doses of progestin were used in continuous-combined than in sequential EPT. We observed no overall difference in risk for lobular vs ductal carcinoma but did observe a slightly higher risk for current vs past EPT use.

Hormone replacement therapy: pathobiological aspects of hormone-sensitive cancers in women relevant to epidemiological studies on HRT: a mini-review

Hormone replacement therapy (HRT) has gained widespread and in some areas indiscriminate use. In reference to recent epidemiological studies which showed unexpected and controversial associations of HRT use with malignant tumours, here we review the current understanding of the dynamics of tumour growth. The pathomorphological characteristics and sex hormone sensitivity of cancers of the breast, endometrium, ovary and colon are discussed. The development of cancer from the first malignant tumour cell to clinical diagnosis takes many years. Hormones can influence tumour growth, but it is questionable whether hormones induce malignant tumours de novo. It is much more likely that hormones 'merely' promote the growth of already existing tumour cells. The long developmental process of tumours is in apparent contradiction to results of some epidemiological studies that describe an increased cancer risk, implying primary initiation, in HRT users within observation periods of 1-6 years. The mechanisms of initiation versus promotion of hormone-sensitive cancers, particularly breast cancer, are only partly understood. The conventional methods of epidemiological studies cannot detect potential risk factors without bias if they do not include a pathomorphological component on growth characteristics. The results of previous studies should be interpreted with great caution with regard to tumour biology.

Postmenopausal hormone therapy: Critical reappraisal and a unified hypothesis

OBJECTIVE

To reconcile apparently conflicting evidence regarding the use of hormone therapy as a health-preserving strategy in postmenopausal women in light of that fact that findings from animal studies, human observation studies, and human clinical trials are consistent for outcomes such as fracture and breast cancer but differ for coronary heart disease (CHD).

DESIGN

Literature review and generation of a unified hypothesis consistent with all of the data.

SETTING

Animal trials, human observational studies, human studies of biologic intermediates, and human clinical trials.

PATIENT(S)

Premenopausal and postmenopausal women with or without antecedent CHD.

MAIN OUTCOME MEASURE(S)

Coronary heart disease events, proxies, risk factors, and related mechanisms.

RESULT(S)

The complex CHD responses to hormone therapy in recent human trials likely reflect a combination of [1] early erosion/rupture of "vulnerable" coronary plaque, which is made worse by hormone therapy, [2] long-term reduction in plaque formation, which is improved by hormone therapy, and [3] modulation of the vasculoprotective actions of estrogens by systemic progestogens.

CONCLUSION(S)

The unified hypothesis predicts that hormone therapy initiated at the time of menopause should produce a decrease in CHD over time. In contrast, hormone therapy begun years after menopause should produce an increase in CHD events shortly after therapy is begun, followed later by benefit. In women who require progestogens for endometrial protection, there should be greater CHD benefit from use of progestogens with less systemic activity. The unified hypothesis is consistent both with plausible biologic mechanisms and with evidence from animal studies, human observational studies, and human clinical trials such as the Women's Health Initiative. In the absence of evidence from human trials that specifically involve initiation of hormone therapy in perimenopausal women, practitioners and patients can use the unified hypothesis as a rational tool to guide decisions about clinical management.

A Predictive Model for the Development of Hormone-Responsive Breast Cancer

BACKGROUND

Effective therapies to reduce the risk of hormone-sensitive breast cancers (ER or PR positive) exist. Available models predict the risk of breast cancer without addressing hormone receptor status. The purpose of this study was to identify risk factors predictive of the development of hormone-sensitive cancers.

METHODS

A total of 1285 invasive breast cancers in 1263 women were identified from a prospectively maintained database. Risk factors were compared for ER+ and ER- cancers by using Fisher's exact test.

RESULTS

Models were developed for premenopausal and postmenopausal women. In premenopausal women, white race, age at menarche < 12 years, and nulliparity or age at first birth > 20 years were used. The risk of ER+ cancer increased from 67.7% with 0 variables to 83.8% with all three (P = .013). In postmenopausal women, white race and a history of estrogen therapy were used. With none of the variables present, the incidence of ER+ cancer was 70.0%; it was 77.6% with one variable and 85.4% with both variables (P = .002). In postmenopausal women, variables predicted significant differences in hormone sensitivity only for those aged < or = 60 years. In the subset of women with information on alcohol use, adding this variable to the model improved the prediction of hormonal status.

CONCLUSIONS

Our findings, if prospectively validated, may help identify those who would obtain the greatest benefit from hormonal chemoprevention strategies for breast cancer risk reduction.

Alcohol Exposure and Breast Cancer: Results of the Women's Contraceptive and Reproductive Experiences Study

Objectives: To explore associated biological outcomes and clarify the role of timing of exposure in the alcohol-breast cancer relationship.

Methods: In a population-based study of 4,575 women ages 35 to 64 years diagnosed with invasive breast cancer between 1994 and 1998 and 4,682 controls, we collected details of lifetime alcohol use and factors that could confound or modify the alcohol-breast cancer relationship. We used conditional logistic regression to compute the odds of breast cancer among drinkers relative to nondrinkers at all ages and at ages 35 to 49 and 50 to 64 years separately.

Results: Recent consumption (at reference age minus two) of ≥7 drinks per week was associated with increased risk [odds ratio (OR), 1.2; 95% CI, 1.01-1.3] and evidence of dose response was observed. Most of the excess was observed among women ages 50-64 years (OR 1.3; 95% CI, 1.1-1.6), although the test for age interaction was not statistically significant. Exposure later in life seemed more important than early exposure. Excess breast cancer associated with recent consumption was restricted to localized disease. When outcome was examined according to tumor hormone receptor status, highest risks were observed for estrogen receptor–positive/progesterone receptor–negative tumors (OR 1.6; 95% CI, 1.2-2.3).

Conclusions: The effect of timing of alcohol exposure on breast cancer risk is complicated and will require additional study focused on this one issue. Further work is needed to explain how alcohol exposure, sex hormones, and tumor receptor status interact.

Association of hormone replacement therapy to estrogen and progesterone receptor status in invasive breast carcinoma

BACKGROUND

Observational studies and randomized trials have demonstrated that hormone replacement therapy (HRT) increases the recipient's risk of developing breast carcinoma. Because it is known that some breast malignancies are hormonally responsive and that others are not, it has been hypothesized that HRT may be associated with the development of estrogen receptor (ER)-positive/progesterone receptor (PR)-positive breast carcinoma more so than with the development of ER-negative/PR-negative breast carcinoma.

METHODS

The Nurses' Health Study is a prospective cohort study that enrolled 121,700 female registered nurses ages 30-55 years in 1976. In the current study, the authors analyzed 2548 malignancies that developed among eligible postmenopausal women in that cohort between 1980 and 2000 and for which data on ER and PR status were available.

RESULTS

Compared with women who had never used HRT, current long-term users of HRT were more likely to develop ER-positive/PR-positive breast carcinoma (multivariate risk ratio [RR], 1.80; 95% confidence interval [CI], 1.52-2.12) but were not any more likely to develop ER-negative/PR-negative disease (multivariate RR, 1.00; 95% CI, 0.72-1.39). This effect grew stronger with increasing duration of current HRT use and was also more pronounced among women with body mass index < 25 kg/m2. Furthermore, the association between HRT use and ER-positive/PR-positive disease was stronger among patients receiving combined HRT (CHRT) regimens, which included estrogen and progesterone, than among users of estrogen alone (ERT). In addition, tumors tended to develop more quickly in current users of CHRT than in ERT users.

CONCLUSIONS

The finding that current users of HRT were more likely to develop ER-positive/PR-positive tumors than they were to develop ER-negative/PR-negative ones suggests that both endogenous and exogenous hormonal factors may influence breast tumor characteristics. In analyses of the effects of hormonal factors on breast tumor development, ER-positive/PR-positive tumors and ER-negative/PR-negative tumors should be considered separately from each other.

Breast cancer with different prognostic characteristics developing in Danish women using hormone replacement therapy

The aim of this study is to investigate the risk of developing prognostic different types of breast cancer in women using hormone replacement therapy (HRT). A total of 10 874 postmenopausal Danish Nurses were followed since 1993. Incident breast cancer cases and histopathological information were retrieved through the National Danish registries. The follow-up ended on 31 December 1999. Breast cancer developed in 244 women, of whom 172 were invasive ductal carcinomas. Compared to never users, current users of HRT had an increased risk of a hormone receptor-positive breast cancer, but a neutral risk of receptor-negative breast cancer, relative risk (RR) 3.29 (95% confidence interval (CI): 2.27–4.77) and RR 0.99 (95% CI: 0.42–2.36), respectively (P for difference=0.013). The risk of being diagnosed with low histological malignancy grade was higher than high malignancy grade with RR 4.13 (95% CI: 2.43–7.01) and RR 2.17 (95% CI: 1.42–3.30), respectively (P=0.063). For breast cancers with other prognostic characteristics, the risk was increased equally for the favourable and nonfavourable types. Current users of HRT experience a two- to four-fold increased risk of breast cancer with various prognostic characteristics, both the favourable and nonfavourable types. For receptor status, the risk with HRT was statistically significantly higher for hormone receptor-positive breast cancer compared to receptor-negative breast cancer.

The characteristics of malignant breast tumors in hormone replacement therapy users versus nonusers

BACKGROUND

The purpose of this study was to investigate the characteristics of breast cancer in hormone replacement therapy (HRT) users vs. nonusers.

METHODS

We investigated the characteristics of all patients between the ages of 50 and 75 years with breast tumors. Then, an age-adjusted group of 55 nonusers was chosen to match and compare with HRT users.

RESULTS

Of the 243 patients available for evaluation, 55 (22.6%) used HRT. Disease stages in HRT users vs. nonusers were as follows: ductal carcinoma in situ (DCIS), 20% and 17.1%; stage I, 45.5% and 41.7%; stage II, 30.9% and 26.2%; stage III, 3.6% and 13.4%; and stage IV, 0% and 1.6% (P =.27). In the age-adjusted cohort, stages in nonusers were as follows: DCIS, 7.3%; stage I, 47.3%; stage II, 25.5%; stage III, 20%; and stage IV, 0% (P =.03). Tumor grades in HRT users vs. nonusers were as follows: grade I, 30.4% and 15.7%; grade II, 52.2% and 52.2%; and grade III, 17.4% and 32.1% (P =.035). Grades in cohort nonusers were as follows: I, 13.2%; II, 52.8%; and III, 34% (P =.05). In the invasive tumors, the positive estrogen receptor (ER) rates were 81.6% and 85.7% (P =.89); positive progesterone receptor (PR) rates were 53.1% and 54% (P =.95); and Her 2-neu positive rates were 18.4% and 17.6% (P =.95), respectively. No significant difference was found in intratumor DCIS, vascular invasion, and Ki-67 (P =.14,.9, and.79, respectively). The rate of lobular and favorable histological types was higher in the HRT user group: 26.6% vs. 15%.

CONCLUSIONS

Breast tumors in HRT users vs. nonusers were of a significantly lower stage and grade and accounted for a higher number of favorable histological types, but all other parameters were similar in the two groups.

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.

Rating the risk factors for breast cancer

OBJECTIVE

To update and summarize evidence of risk factors for breast cancer.

SUMMARY BACKGROUND DATA

Women who are at high risk for breast cancer have a variety of options available to them, including watchful waiting, prophylactic surgery, and chemoprevention. It is increasingly important to accurately assess a patient's risk profile to ensure that the cost/benefit ratio of the selected treatment is favorable.

METHODS

Estimates of relative risk for documented risk factors were obtained from seminal papers identified in previous reviews. These estimates were updated where appropriate with data from more recent reports using large sample sizes or presenting meta-analyses of previous studies. These reports were identified from a review of the Medline database from 1992 to 2002.

RESULTS

Risk factors that have received a great deal of publicity (hormone use, alcohol consumption, obesity, nulliparity) present a relatively modest relative risk for breast cancer (<2). Factors associated with a prior history of neoplastic disease or atypical hyperplasia and factors associated with a genetic predisposition significantly affect the risk of breast cancer, with relative risks ranging from 3 (for some cases of positive family history) to 200 (for premenopausal women positive for a BRCA mutation).

CONCLUSIONS

More precise tools, based on techniques of molecular biology such as microarray analysis, will be needed to assess individual risk for breast cancer.

The menopause, hormone replacement therapy and breast cancer

Concern exists that the reduction in breast cancer risk associated with the onset of the menopause will be negated with exposure to hormone replacement therapy (HRT). Evidence from large-scale randomised HRT trials support observational data that have shown a modest increase in breast cancer risk with long-term use (i.e. >15 years) of combined therapy, although this falls following HRT cessation suggesting a growth-promoting effect. Randomised evidence demonstrates that the efficacy of anti-estrogens, aromatase inhibitors and raloxifene in the treatment and chemoprevention of breast cancer are restricted to women with oestrogen receptor positive (ER +ve) disease; however, HRT has not been associated conclusively with a predominance of hormone sensitive breast cancer. Despite stimulating the breast cancer cell growth, HRT has not been shown to increase breast cancer recurrence or mortality when prescribed to breast cancer survivors experiencing oestrogen deficiency symptoms and randomised trials have been recommended and commenced. In conjunction with controlled breast cancer trials demonstrating a therapeutic benefit of high dose estrogens and interest in the use of additive oestrogen therapy in patients developing resistance to oestrogen deprivation, the dogma that HRT is an absolute contra-indication following diagnosis is challenged.

Progesterone receptors--animal models and cell signalling in breast cancer. Implications for breast cancer of inclusion of progestins in hormone replacement therapies

Progestins are included in menopausal hormone replacement therapy to counteract the increased risk for endometrial cancer associated with estrogen replacement therapy. Studies of hormone replacement therapy and breast cancer risk and of changes in mammographic density according to different regimens of hormone replacement therapy suggest that, for the most part, estrogen-progestin replacement therapy has a more adverse effect on breast cancer risk than does estrogen replacement therapy. Many questions remain unresolved, however, including risk associated with different regimens of estrogen-progestin replacement therapy, and whether the effects vary according to tumor characteristics, such as histology, extent of disease, and hormone receptor status.