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

Modifiable risk factors in women at high risk of breast cancer: a systematic review

BACKGROUND

Modifiable risk factors (alcohol, smoking, obesity, hormone use, and physical activity) affect a woman's breast cancer (BC) risk. Whether these factors affect BC risk in women with inherited risk (family history, BRCA1/2 mutations, or familial cancer syndrome) remains unclear.

METHODS

This review included studies on modifiable risk factors for BC in women with inherited risk. Pre-determined eligibility criteria were used and relevant data were extracted.

RESULTS

The literature search resulted in 93 eligible studies. For women with family history, most studies indicated that modifiable risk factors had no association with BC and some indicated decreased (physical activity) or increased risk (hormonal contraception (HC)/menopausal hormone therapy (MHT), smoking, alcohol). For women with BRCA mutations, most studies reported no association between modifiable risk factors and BC; however, some observed increased (smoking, MHT/HC, body mass index (BMI)/weight) and decreased risk (alcohol, smoking, MHT/HC, BMI/weight, physical activity). However, measurements varied widely among studies, sample sizes were often small, and a limited number of studies existed.

CONCLUSIONS

An increasing number of women will recognize their underlying inherited BC risk and seek to modify that risk. Due to heterogeneity and limited power of existing studies, further studies are needed to better understand how modifiable risk factors influence BC risk in women with inherited risk.

Prognostic Impact of Menopausal Hormone Therapy in Breast Cancer Differs According to Tumor Characteristics and Treatment

This study investigated how a history of menopausal hormone therapy (MHT) impacts clinical outcomes overall and in different subgroups of breast cancer patients. The study included 814 primary breast cancer patients aged ≥50 years in Sweden (2002–2012) with follow-up until 2016. Associations between patient- and tumor characteristics, recurrences, and overall survival were analyzed in relation to MHT. After a median follow-up of 7 years, 119 recurrences, and 111 deaths occurred. Ever MHT (n = 433, 53.2%) was associated with a lower BMI, frequency of alcohol abstinence, and histological grade, higher frequency of oral contraceptive use, and lobular cancer. Overall, MHT was not associated with prognosis, but there were significant effect modifications by estrogen receptor (ER) status, node status, main histological type, and aromatase inhibitor (AI) treatment on recurrence-risk (all P_interactions≤ 0.017). MHT conferred an increased recurrence-risk in patients with ER- tumors, adjusted Hazard Ratio (HR_adj) 3.99 (95% Confidence Interval (CI) 1.40–11.33), in node-negative patients HR_adj 1.88 (95% CI 1.11–3.17), and in non-AI-treated patients HR_adj 1.81 (95% CI 1.01–3.24), but decreased recurrence-risk in AI-treated patients HR_adj 0.46 (95% CI 0.25–0.84) and in patients with lobular cancer HR_adj 0.15 (95% CI 0.04–0.64). MHT was associated with lower risk of death in node-positive patients HR_adj of 0.48 (95% CI 0.27–0.86) and in AI-treated patients HR_adj of 0.41 (95% CI 0.22–0.77), but not in other patients (both P_interactions≤ 0.027). A history of MHT may have prognostic value for certain subgroups of breast cancer patients such as AI-treated or node-negative patients.

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

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

Hormone-related pathways and risk of breast cancer subtypes in African American women

We sought to investigate genetic variation in hormone pathways in relation to risk of overall and subtype-specific breast cancer in women of African ancestry (AA). Genotyping and imputation yielded data on 143,934 SNPs in 308 hormone-related genes for 3663 breast cancer cases (1098 ER-, 1983 ER+, 582 ER unknown) and 4687 controls from the African American Breast Cancer Epidemiology and Risk (AMBER) Consortium. AMBER includes data from four large studies of AA women: the Carolina Breast Cancer Study, the Women's Circle of Health Study, the Black Women's Health Study, and the Multiethnic Cohort Study. Pathway- and gene-based analyses were conducted, and single-SNP tests were run for the top genes. There were no strong associations at the pathway level. The most significantly associated genes were GHRH, CALM2, CETP, and AKR1C1 for overall breast cancer (gene-based nominal p ≤ 0.01); NR0B1, IGF2R, CALM2, CYP1B1, and GRB2 for ER+ breast cancer (p ≤ 0.02); and PGR, MAPK3, MAP3K1, and LHCGR for ER- disease (p ≤ 0.02). Single-SNP tests for SNPs with pairwise linkage disequilibrium r (2) < 0.8 in the top genes identified 12 common SNPs (in CALM2, CETP, NR0B1, IGF2R, CYP1B1, PGR, MAPK3, and MAP3K1) associated with overall or subtype-specific breast cancer after gene-level correction for multiple testing. Rs11571215 in PGR (progesterone receptor) was the SNP most strongly associated with ER- disease. We identified eight genes in hormone pathways that contain common variants associated with breast cancer in AA women after gene-level correction for multiple testing.

Breast cancer in Wales: time trends and geographical distribution

BACKGROUND

Breast cancer is the second commonest malignancy in the world. In 2012, approximately 522,000 women died of breast cancer across the world. The aim of this study is to provide an up-to-date analysis of time trends in incidence, geographical distribution, survival and mortality from breast cancer in Wales.

METHODS

Breast cancer cases registered between 1985 and 2012 were identified from the Welsh Cancer Intelligence and Surveillance Unit (WCISU). A Poisson regression model was fitted to assess temporal trends and rate ratios (RR) and 95% confidence intervals (CI) were determined and compared in relation to age, geographical distribution and mortality across time periods.

RESULTS

A total of 60,227 women diagnosed with breast cancer were registered with the Welsh cancer registry between 1985 and 2012. The age-standardised incidence rate of breast cancer was 113.4 per 100,000 populations over the entire study period. There has been a significant increase in the incidence of breast cancer over the study period, although a slight decline was recorded towards the end of the study. There is a considerable regional variation in incidence, with a higher incidence rate in the rural areas compared to urban areas (P<0.001). One- and five-year relative survival improved from 83.3 and 64.2 respectively in 1985-1989 to 91.1 and 78.8 respectively in 2000-2004. There has also been a considerable improvement in relative survival across all age groups. Mortality has improved over the study period with the most dramatic decline in the age groups 45-54 and 55-64 years (P<0.001).

CONCLUSIONS

There has been a significant increase in the incidence of breast cancer in Wales over the last three decades, which is likely to be partly due to the introduction of the National Health Service Breast Screening Programme. Breast cancer incidence is higher in rural areas than urban areas and lower incidence was seen in more deprived areas. There was a considerable decline in mortality rate across almost all age groups, especially in recent years. However, women over the age of 65 years had poorer outcome throughout the study period.

Oral contraceptives, hormone replacement therapy and breast cancer risk: a cohort study of 16 928 women 48 years and older

BACKGROUND

Findings on potential interactive effects of oral contraceptives (OCs) and hormone replacement therapy (HRT) on breast cancer risk have been inconsistent. We aimed to use population-based cohort data to determine whether former use of OCs affects breast cancer risk among HRT users, taking into account regimens of HRT, duration and currency of use.

METHODS

The cohort consisted of 16 928 Icelandic women who visited the Icelandic Cancer Detection Clinic in 1979-2006 and provided information on use of OCs and HRT when they were 48 years or older. By record linkage to the Icelandic Cancer Registry, all breast cancer diagnosed during follow-up was identified. Using Cox regression, hazard ratios (HRs) for breast cancer according to hormone use were estimated, adjusting for menstrual and reproductive risk factors. Also, interaction analyses were carried out.

RESULTS

Breast cancer risk was significantly increased among ever users of combined estrogen and progestin (EP-HRT) preparations (HR=2.61; 95% CI 2.00-3.41) and not among users of estrogen-only regimens (E-only HRT) (HR=1.13; 95% CI 0.85-1.49). Ever users of both OCs and HRT had higher breast cancer risk than users of only one of the two (HR=2.19; 95% CI 1.67-2.87). After restricting the analysis to EP-HRT and focusing on long-term and current use, there was an indication of a negative interaction with ever OC use (p=0.06); HR=2.87; 95% CI 1.79-4.60 for never OC users and HR=2.24; 95% CI 1.51-3.34 for former OC users.

CONCLUSION

After taking HRT regimen, duration and currency of use into account, the results of our population-based cohort study do not support the notion that former OC use increases breast cancer risk among HRT users, on the contrary there was an indication of a slightly lower risk in former OC users, restricted to current, long-term EP-HRT users.

Postmenopausal hormone therapy and breast cancer risk: current status and unanswered questions

Many women take hormone therapy (HT) for menopausal symptom relief. Studies have tried to clarify whether various factors can modify the risk of HT, such as the age at initiation, dose, duration, or type of HT, or characteristics of the individual, such as family history or body mass index. The relative risks of breast cancer associated with HT across various subgroups of women should be considered similar, but absolute risks can vary significantly among women and this may inform individual decision making. For breast cancer survivors, systemic HT should be discouraged.

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.

Genetic variation in the progesterone receptor and metabolism pathways and hormone therapy in relation to breast cancer risk

The relevance of progesterone to breast carcinogenesis is highlighted by evidence indicating that use of combined estrogen-progesterone therapy (EPT) is more strongly related to breast cancer risk than is use of unopposed estrogen therapy. However, few investigators have assessed how genetic variation in progesterone-related genes modifies the effect of EPT on risk. In an analysis combining data from 2 population-based case-control studies of postmenopausal breast cancer (1,296 cases and 1,055 controls) conducted in Washington State in 1997-1999 and 2000-2004, the authors evaluated how 51 single nucleotide polymorphisms in 7 progesterone-related genes (AKR1C1, AKR1C2, AKR1C3, CYP3A4, SRD5A1, SRD5A2, and PGR) influenced breast cancer risk. There was no appreciable association with breast cancer risk overall for any single nucleotide polymorphism. For rs2854482 in AKR1C2, carrying 1 or 2 A alleles was associated with a 2.0-fold increased breast cancer risk in EPT users (95% confidence interval: 1.0, 4.0) but not in never users (P(heterogeneity) = 0.03). For rs12387 in AKR1C3, the presence of 1 or 2 G alleles was associated with a 1.5-fold increased risk among EPT users (95% confidence interval: 1.1, 2.2) but not in never users (P(heterogeneity) = 0.02). Interpretation of these subgroup associations must await the results of similar studies conducted in other populations.

Hormone replacement therapy is more prevalent among Jewish BRCA1/2 mutation carriers

The aim of this study was to compare reproductive factors, use of oral contraceptives (OC) and hormone replacement therapy (HRT) in consecutive Jewish Ashkenazi breast cancer patients, with and without BRCA1/BRCA2 mutations. Jewish Israeli women with breast cancer (n=385) were genotyped for the three predominant Jewish mutations in BRCA1 and BRCA2, and data on reproductive factors, OC and HRT use, were analyzed using logistic regression analyses. Overall, 28/385 (7.3%) of participants were mutation carriers, the majority of whom were Ashkenazi (n=22; 78.6%) and were diagnosed with breast cancer at or under age 49 years (n=18; 64.3%). Mutation carriers were more likely than non-carriers to ever use OC (39.3% vs. 20.2%; P=0.053), HRT (35.7% vs. 13.7%; P=0.007), and have first menarche at or below 12 years of age (71.4% vs. 40.6%; P=0.03). Multivariate analysis showed that Ashkenazi women diagnosed with breast cancer under 40 years of age, with a family history of breast/ovarian cancer, who ever used HRT were more likely to be mutation carriers. This study has shown that HRT use is more prevalent among Jewish Ashkenazi mutation carriers, but its role in modifying breast cancer risk in mutation carriers remains unknown.

Current Status of Combined Hormone Replacement Therapy in Clinical Practice

Approximately 20 million women worldwide use hormone replacement therapy (HRT). Formerly, it was thought to confer beneficial cardiac protection and reduce osteoporosis in addition to relieving the symptoms of menopause. However, many recent trials have contradicted these beliefs. The risk of breast cancer associated with HRT use has been well documented but underestimated. Many recent trials have reported higher than expected breast cancer incidence rates, particularly associated with combined HRT. Although it was believed estrogen conferred cardiac protection and reduced the incidence of myocardial ischemic events and cerebrovascular accidents, the more recent literature indicates that this is not true and that HRT users have a higher risk of cardiac and cerebral events. The role of HRT in clinical practice has been redefined. It is no longer an acceptable form of treatment for most women. The evidence indicates that the use of long-term HRT is no longer clinically justifiable.

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.

A candidate gene approach to searching for low-penetrance breast and prostate cancer genes

Most cases of breast and prostate cancer are not associated with mutations in known high-penetrance genes, indicating the involvement of multiple low-penetrance risk alleles. Studies that have attempted to identify these genes have met with limited success. The National Cancer Institute Breast and Prostate Cancer Cohort Consortium--a pooled analysis of multiple large cohort studies with a total of more than 5,000 cases of breast cancer and 8,000 cases of prostate cancer--was therefore initiated. The goal of this consortium is to characterize variations in approximately 50 genes that mediate two pathways that are associated with these cancers--the steroid-hormone metabolism pathway and the insulin-like growth factor signalling pathway--and to associate these variations with cancer risk.

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.

Associations among circulating sex hormones, insulin-like growth factor, lipids, and mammographic density in postmenopausal women

OBJECTIVE

Hormone therapy use has been positively associated with mammographic density in several studies. However, few studies have examined the association between endogenous hormone levels and mammographic density. Therefore, we evaluated the relationship of endogenous sex hormones, insulin-like growth factor (IGF), and lipids with mammographic density in 88 overweight, postmenopausal women not taking hormone therapy.

METHODS

Percent density and dense area were evaluated as continuous measures using a computer-assisted program. We used multiple linear regression to evaluate the associations of sex hormones, IGF, and cholesterol with mammographic density, adjusting for confounders, including adiposity. We evaluated stratification by history of hormone therapy use (former versus never) and hormone therapy latency (<5 versus > or = 5 years).

RESULTS

Among former hormone therapy users, mammographic density was inversely associated with circulating levels of estrone (P = 0.01), estradiol (P = 0.003), free estradiol (P = 0.004), testosterone (P = 0.04), free testosterone (P = 0.02), androstenedione (P < 0.001), dehydroepiandrosterone (P = 0.01), and the ratio of IGF-I to its binding protein (IGF-I/IGFBP-3; P = 0.04). We found similar associations when we limited the analyses to women who had used hormone therapy within the past 5 years. We also noted positive associations of mammographic density with total cholesterol (P = 0.03) and low-density lipoprotein (P = 0.03) among former hormone therapy users. No associations were noted among women who had never used hormone therapy.

CONCLUSIONS

These results suggest that there is an inverse relationship between endogenous sex hormones and mammographic density in postmenopausal women among former users of hormone therapy. This is not consistent with the hormone therapy literature and should be confirmed in larger studies.

The effect of continuous oestradiol with intermittent norgestimate on bone mineral density and bone turnover in post-menopausal women

OBJECTIVE

To assess in post-menopausal women the efficacy and tolerability of a continuous oestradiol/intermittent norgestimate HRT regimen to prevent and to reverse post-menopausal loss of bone mineral density (BMD) and to determine the effects on serum bone turnover markers markers.

METHODS

A 1-year, multicentre, international, placebo-controlled, randomised, double-blind clinical trial was conducted in 146 post-menopausal women with an intact uterus in order to assess the effect on bone loss of continuous oral 17beta-oestradiol (1 mg per day) combined with norgestimate (90 microg per day), for 3 consecutive days out of every 6-day treatment period (E2/iNGM). During a second year extension, all women agreeing to continue were on the E2/iNGM regimen. BMD was assessed prior to treatment and after 1 and 2 years or at the end of treatment in women stopping participation prematurely after at least 6 months of treatment. Serum bone turnover markers were determined prior to and at 1 year of treatment Adverse events were collected at three-monthly intervals during clinic visits over the treatment period.

RESULTS

BMD in the lumbar spine, the primary endpoint, was evaluable in 117 subjects completing >6 months of treatment. BMD increased on average by 2.4% in women on the intermittent progestin regimen. It decreased by 1.4% in placebo treated women. The change from baseline and the difference between active and placebo treatment (Delta placebo) were highly significant (P < 0.0001). On E2/iNGM, also the BMD in the total hip increased (+1.49%, Delta placebo 3.73%, P < 0.0001). The serum markers for bone formation osteocalcin and type I collagen N-propeptide were significantly reduced compared to baseline by 31 and 44%, respectively and the bone resorption marker C-terminal crosslinked telopeptide of type I collagen by 59%. Minor increases (<10%) of markers in the placebo group were not significant. During a second year extension of the trial, all subjects were on active treatment. Subjects on placebo who lost (median+/-CI 95%) 0.66% (-2.3 to +0.5) of spine BMD during the first year now gained 4.41% (2.7-7.6). They also gained 1.6% (0.1-0.3.6) in the total hip. Subjects continuously on oestradiol/intermittent norgestimate (E2/iNGM) gained an additional 5.7% (2.3-13.5) in the lumbar spine and +0.1% (-0.6 to +2.2) at the total hip. Side effects reported by women on the intermittent progestin regimen significantly in excess over reports from the placebo group were uterine bleeding, abdominal and breast pain, but not headache. Back pain and weight gain was reported by significantly fewer women on active treatment compared to placebo.

CONCLUSION

The continuous oestradiol/intermittent norgestimate HRT regimen is well tolerated, reduces bone turnover and prevents post-menopausal bone loss in healthy post-menopausal women.

Effect of a yearlong, moderate-intensity exercise intervention on the occurrence and severity of menopause symptoms in postmenopausal women

OBJECTIVE

To evaluate the effect of moderate-intensity exercise on the occurrence and severity of menopause symptoms.

DESIGN

A yearlong, randomized, clinical trial, conducted in Seattle, WA, with 173 overweight, postmenopausal women not taking hormone therapy in the previous 6 months. The intervention was a moderate-intensity exercise intervention (n = 87) versus stretching control group (n = 86). Using logistic regression, odds ratios comparing exercise with controls were calculated at 3, 6, 9, and 12 months for menopause symptoms and their severity.

RESULTS

There was a significant increase in hot flash severity and decreased risk of memory problems in exercisers versus controls over 12 months, although the numbers affected were small. No other significant changes in symptoms were observed.

CONCLUSIONS

Exercise does not seem to decrease the risk of having menopause symptoms in overweight, postmenopausal women not taking hormone therapy and may increase the severity of some symptoms in a small number of women.

A comparative review of the risks and benefits of hormone replacement therapy regimens

The Women's Health Initiative (a large, randomized, placebo-controlled trial) investigated the effect of conjugated equine estrogens combined with medroxyprogesterone acetate on specific potential long-term benefits and risks. A review of the clinical studies that have investigated different types and regimens of estrogens combined with progestins was conducted to assess how applicable the results of the Women's Health Initiative are to hormone replacement therapy regimens in general. The studies that were reviewed were limited to randomized clinical trials and observational studies that have been published over the last 15 years (1987-2002) and to meta-analyses and reviews that may have included the literature before 1987. The increased risks for venous thromboembolism, stroke, coronary heart disease, and breast cancer that were identified in the Women's Health Initiative trial have also been reported with postmenopausal hormone therapies that contain a variety of estrogen and progestin products. The beneficial effects that were noted in the Women's Health Initiative, with respect to reductions in fractures and colorectal cancer, have not been evaluated in large, randomized controlled trials that use different estrogen/progestin combinations; however, observational trials that used a variety of estrogen or hormone replacement therapy products and randomized clinical studies that evaluated bone mineral density (an excellent predictor of fracture risk) with different estrogen/hormone replacement therapy regimens would suggest that results would be similar to those found in the Women's Health Initiative. Although the relief of menopausal symptoms, the primary reason women seek treatment, was not included in the overall benefit/risk analysis of the Women's Health Initiative, numerous trials suggest that all therapies are effective. Overall, these data indicate that the benefit/risk analysis that was reported in the Women's Health Initiative can be generalized to all postmenopausal hormone replacement therapy products.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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