Hormone replacement therapy and the sensitivity and specificity of breast cancer screening: a review

Type and timing of menopausal hormone therapy and breast cancer risk: individual participant meta-analysis of the worldwide epidemiological evidence

BACKGROUND

Published findings on breast cancer risk associated with different types of menopausal hormone therapy (MHT) are inconsistent, with limited information on long-term effects. We bring together the epidemiological evidence, published and unpublished, on these associations, and review the relevant randomised evidence.

METHODS

Principal analyses used individual participant data from all eligible prospective studies that had sought information on the type and timing of MHT use; the main analyses are of individuals with complete information on this. Studies were identified by searching many formal and informal sources regularly from Jan 1, 1992, to Jan 1, 2018. Current users were included up to 5 years (mean 1·4 years) after last-reported MHT use. Logistic regression yielded adjusted risk ratios (RRs) comparing particular groups of MHT users versus never users.

FINDINGS

During prospective follow-up, 108 647 postmenopausal women developed breast cancer at mean age 65 years (SD 7); 55 575 (51%) had used MHT. Among women with complete information, mean MHT duration was 10 years (SD 6) in current users and 7 years (SD 6) in past users, and mean age was 50 years (SD 5) at menopause and 50 years (SD 6) at starting MHT. Every MHT type, except vaginal oestrogens, was associated with excess breast cancer risks, which increased steadily with duration of use and were greater for oestrogen-progestagen than oestrogen-only preparations. Among current users, these excess risks were definite even during years 1-4 (oestrogen-progestagen RR 1·60, 95% CI 1·52-1·69; oestrogen-only RR 1·17, 1·10-1·26), and were twice as great during years 5-14 (oestrogen-progestagen RR 2·08, 2·02-2·15; oestrogen-only RR 1·33, 1·28-1·37). The oestrogen-progestagen risks during years 5-14 were greater with daily than with less frequent progestagen use (RR 2·30, 2·21-2·40 vs 1·93, 1·84-2·01; heterogeneity p<0·0001). For a given preparation, the RRs during years 5-14 of current use were much greater for oestrogen-receptor-positive tumours than for oestrogen-receptor-negative tumours, were similar for women starting MHT at ages 40-44, 45-49, 50-54, and 55-59 years, and were attenuated by starting after age 60 years or by adiposity (with little risk from oestrogen-only MHT in women who were obese). After ceasing MHT, some excess risk persisted for more than 10 years; its magnitude depended on the duration of previous use, with little excess following less than 1 year of MHT use.

INTERPRETATION

If these associations are largely causal, then for women of average weight in developed countries, 5 years of MHT, starting at age 50 years, would increase breast cancer incidence at ages 50-69 years by about one in every 50 users of oestrogen plus daily progestagen preparations; one in every 70 users of oestrogen plus intermittent progestagen preparations; and one in every 200 users of oestrogen-only preparations. The corresponding excesses from 10 years of MHT would be about twice as great.

FUNDING

Cancer Research UK and the Medical Research Council.

Estimation of the benefit and harms of including clinical breast examination in an organized breast screening program

BACKGROUND

There is controversy about the value of clinical breast examination (CBE) in addition to mammography for breast screening. The study investigates the associations between risk factors such as mammographic density, hormone therapy use and family history and the effectiveness of screening mammography with or without CBE.

METHODS

The cohort consists of women 50-69 years old screened at the Ontario Breast Screening Program. The associations of the risk factors were investigated using a joint logistic regression model that accommodates the partially unobserved disease status, clustered data structures, individual risk factors, and the dependence between true and false detection.

RESULTS

Having high mammographic density, a first degree relative with breast cancer and using hormone therapy generally increased a woman's probability of being referred correctly. For low risk group (defined as without dense breasts, family history, and not currently using hormone therapy), the average loss of specificity ranged from 3.6% to 5.7% and the gain of sensitivity was between 10.6% and 21.2% with the addition of CBE.

CONCLUSIONS

The addition of CBE to mammography would increase the overall sensitivity and decrease the specificity. CBE can be targeted to those women in which it has the highest net benefit.

Digital versus screen-film mammography: impact of mammographic density and hormone therapy on breast cancer detection

Most studies that have examined the effects of mammographic density and hormone therapy use on breast cancer detection have included screen-film mammography. This study further examines this association in post-menopausal women screened by digital mammography. Approved by the University of Toronto Research Ethics Board, this study identified 688,418 women of age 50-74 years screened with digital or screen-film mammography from 2008 to 2009 within the Ontario Breast Screening Program. Of 2993 eligible women with invasive breast cancer, 2450 were contacted and 1421 participated (847 screen-film mammography, 574 digital direct radiography). Mammographic density was measured by study radiologists using the standard BI-RADS classification system and by a computer-assisted method. Information on hormone therapy use was collected by a telephone-administered questionnaire. Logistic regression and two-tailed tests for significance evaluated associations between factors and detection method by mammography type. Women with >75 % radiologist-measured mammographic density compared to those with <25 % were more likely to be diagnosed with an interval than screen-detected cancer, with the difference being greater for those screened with screen-film (OR = 6.40, 95 % CI 2.30-17.85) than digital mammography (OR = 2.41, 95 % CI 0.67-8.58) and aged 50-64 years screened with screen-film mammography (OR = 10.86, 95 % CI 2.96-39.57). Recent former hormone therapy users were also at an increased risk of having an interval cancer with the association being significant for women screened with digital mammography (OR = 2.08, 95 % CI 1.17-3.71). Breast screening using digital mammography lowers the risk of having an interval cancer for post-menopausal women aged 50-64 with greater mammographic density.

Assessment of mammographic density in postmenopausal women during long term hormone replacement therapy

OBJECTIVE

To assess long-term effects of different hormone replacement therapy (HRT) regimens on mammographic density.

METHODS

One hundred sixty-five postmenopausal women were treated with the same HRT during 5 years: 38 received transdermal estradiol, 78 cyclic combined therapy and 49 continuous combined therapy. Mammograms were obtained at baseline, at 1-year and 5-year treatment. Breast density changes were categorized as slight focal increased density, considerable focal increased density, slight diffuse increased density and considerable diffuse increased density.

RESULTS

Mammographic density increased in 7.9% of women receiving estrogen alone versus 25.2% of women receiving combined therapy (p < 0.022) during 1 year, and in 7.9% of women versus 28.3% of women (p < 0.009) after 5 years of therapy, respectively. There were significant statistical differences in women treated with estrogen alone versus those treated with combined HRT after 1 and 5 years. After 5 years of HRT, breast density increased 21.8% in women receiving cyclic combined therapy versus 38.8% in those under continuous combined therapy (p < 0.039).

CONCLUSION

An increase in breast density is significantly more frequent in women receiving combined estrogen-progestin therapy than in women receiving estrogen alone. There are differences between cyclic and continuous combined therapy at 5 years of treatment.

Systematic review of methods used in meta-analyses where a primary outcome is an adverse or unintended event

BACKGROUND

Adverse consequences of medical interventions are a source of concern, but clinical trials may lack power to detect elevated rates of such events, while observational studies have inherent limitations. Meta-analysis allows the combination of individual studies, which can increase power and provide stronger evidence relating to adverse events. However, meta-analysis of adverse events has associated methodological challenges. The aim of this study was to systematically identify and review the methodology used in meta-analyses where a primary outcome is an adverse or unintended event, following a therapeutic intervention.

METHODS

Using a collection of reviews identified previously, 166 references including a meta-analysis were selected for review. At least one of the primary outcomes in each review was an adverse or unintended event. The nature of the intervention, source of funding, number of individual meta-analyses performed, number of primary studies included in the review, and use of meta-analytic methods were all recorded. Specific areas of interest relating to the methods used included the choice of outcome metric, methods of dealing with sparse events, heterogeneity, publication bias and use of individual patient data.

RESULTS

The 166 included reviews were published between 1994 and 2006. Interventions included drugs and surgery among other interventions. Many of the references being reviewed included multiple meta-analyses with 44.6% (74/166) including more than ten. Randomised trials only were included in 42.2% of meta-analyses (70/166), observational studies only in 33.7% (56/166) and a mix of observational studies and trials in 15.7% (26/166). Sparse data, in the form of zero events in one or both arms where the outcome was a count of events, was found in 64 reviews of two-arm studies, of which 41 (64.1%) had zero events in both arms.

CONCLUSIONS

Meta-analyses of adverse events data are common and useful in terms of increasing the power to detect an association with an intervention, especially when the events are infrequent. However, with regard to existing meta-analyses, a wide variety of different methods have been employed, often with no evident rationale for using a particular approach. More specifically, the approach to dealing with zero events varies, and guidelines on this issue would be desirable.

Estradiol plus drospirenone therapy increases mammographic breast density in perimenopausal women

OBJECTIVE

To investigate the effects of 17β-estradiol 1mg plus drospirenone 2mg (E2/DRSP) treatment on mammographic breast density in perimenopausal women.

STUDY DESIGN

In this prospective study, 80 healthy perimenopausal women aged 41-49 years were enrolled and assigned to either E2/DRSP (n=40) or a control group (n=40). Mammograms were performed at baseline and after 12 months of treatment. Mammographic breast density was quantified according to the Wolfe classification.

RESULTS

We demonstrated an increase in mammographic breast density in 37% (95% CI (confidence interval): 18.8-55.3%) of women treated with E2/DRSP after 12 months. The percentage of women with increased density was 0% (95% CI: 0.0-0.0%) in the control group. The difference in breast density between the E2/DRSP group and the control group was statistically very significant (p<0.001).

CONCLUSIONS

E2/DRSP therapy for 12 months in perimenopausal women significantly increased mammographic breast density in comparison to a control group. Further long-term and large scale prospective studies are needed to evaluate this issue.

Breast tumor characteristics in hormone replacement therapy users

The aim of this study was to further elucidate the influence of HRT use, regarding duration, regimen and route of administration, on breast tumor characteristics. We evaluated the associations between HRT use and breast tumor characteristics in 530 postmenopausal women diagnosed with invasive breast cancer. Detailed information on HRT use and mammographic attendance were collected through a postal questionnaire. Adjusted odds ratios and 95% confidence intervals were calculated using logistic regression. Tumors in HRT users were significantly smaller, more often of ductal histologic type and with lower grade and lower mitotic index compared to tumors in nonusers. Tumor characteristics did not vary significantly by HRT duration, regimen and route of administration, except for mitotic index, which was more often of score 2 in long-term users, and of score 3 in short-term users. Higher mammographic surveillance among HRT users did not explain our results. We conclude that tumors in HRT users have a more favorable prognostic profile regardless of duration, regimen and route of administration. These effects seem to be due to the influence of HRT on preexisting tumors causing their greater differentiation rather than earlier detection due to mammographic surveillance.

An epidemiological overview of the relationship between hormone replacement therapy and breast cancer

Large-scale randomized clinical trials and observational studies have consistently found that use of hormone replacement therapy (HRT) increases the risk of breast cancer. More recently, ecological studies have shown correlations between dramatic reductions in use of HRT in many countries, and declines in the rates of breast cancer in older women. Meta-analyses of data from the trials and observational studies show that the increase in breast cancer risk is greater for combined estrogen-progestin therapies compared with estrogen alone; that for both types of preparation, breast cancer risk increases with duration of use; and that the risks decrease relatively quickly after cessation of use. For both estrogen-only and combined therapies, the risk of breast cancer is higher if therapy is initiated close to the time of the menopause, relative to the risks in women starting HRT later. Most drug regulatory authorities currently recommend that HRT be prescribed only to fully informed women who have moderate-to-severe menopausal symptoms, for the shortest duration possible; and it is recommended that the need for therapy be reviewed at least every 6-12 months.

Breast cancer risk in relation to the interval between menopause and starting hormone therapy

BACKGROUND

Although breast cancer risk is greater in users of estrogen-progestin than estrogen-only formulations of menopausal hormonal therapy, reports on their effects have been somewhat inconsistent. We investigated whether the timing of these therapies affected breast cancer incidence.

METHODS

A total of 1,129,025 postmenopausal UK women provided prospective information on hormonal therapy use and other factors relevant for breast cancer risk. We used Cox regression to estimate adjusted relative risks (RRs) of breast cancer in hormonal therapy users vs never users and calculated standardized incidence rates. All statistical tests were two-sided.

RESULTS

During 4.05 million woman-years of follow-up, 15,759 incident breast cancers occurred, with 7107 in current users of hormonal therapy. Breast cancer incidence was increased in current users of hormonal therapy, returning to that of never users a few years after use had ceased. The relative risks for breast cancer in current users were greater if hormonal therapy was begun before or soon after menopause than after a longer gap (P(heterogeneity) < .001, for both estrogen-only and estrogen-progestin formulations). Among current users of estrogen-only formulations, there was little or no increase in risk if use began 5 years or more after menopause (RR = 1.05, 95% confidence interval [CI] = 0.89 to 1.24), but risk was statistically significantly increased if use began before or less than 5 years after menopause (RR = 1.43, 95% CI = 1.35 to 1.51). A similar pattern was observed among current users of estrogen-progestin formulations (RR = 1.53, 95% CI = 1.38 to 1.70, and RR = 2.04, 95% CI = 1.95 to 2.14, respectively). At 50-59 years of age, annual standardized incidence rates for breast cancer were 0.30% (95% CI = 0.29% to 0.31%) among never users of hormone therapy and 0.43% (95% CI = 0.42% to 0.45%) and 0.61% (95% CI = 0.59% to 0.64%), respectively, among current users of estrogen-only and estrogen-progestin formulations who began use less than 5 years after menopause.

CONCLUSIONS

There was substantial heterogeneity in breast cancer risk among current users of hormonal therapy. Risks were greater among users of estrogen-progestin than estrogen-only formulations and if hormonal therapy started at around the time of menopause than later.

Breast density in women with premature ovarian failure or postmenopausal women using hormone therapy: analytical cross-sectional study

CONTEXT AND OBJECTIVE

Studies on postmenopausal women have reported increased risk of breast cancer relating to the type and duration of hormone therapy (HT) used. Women with premature ovarian failure (POF) represent a challenge, since they require prolonged HT. Little is known about the impact of prolonged HT use on these women's breasts. This study aimed to evaluate the effects of one type of HT on the breast density of women with POF, compared with postmenopausal women.

DESIGN AND SETTING

Cross-sectional study at the Department of Obstetrics and Gynecology, Universidade Estadual de Campinas (Unicamp).

METHODS

31 women with POF and 31 postmenopausal women, all using HT consisting of conjugated equine estrogen combined with medroxyprogesterone acetate, and matched according to HT duration, were studied. Mammography was performed on all subjects and was analyzed by means of digitization or Wolfe's classification, stratified into two categories: non-dense (N1 and P1 patterns) and dense (P2 and Dy).

RESULTS

No significant difference in breast density was found between the two groups through digitization or Wolfe's classification. From digitization, the mean breast density was 24.1% ± 14.6 and 18.1% ± 17.2 in the POF and postmenopausal groups, respectively (P = 0.15). Wolfe's classification identified dense breasts in 51.6% and 29.0%, respectively (P = 0.171).

CONCLUSION

There was no difference in breast density between the women with POF and postmenopausal women, who had used HT for the same length of time. These results may help towards compliance with HT use among women with POF.

Estrogen alone in postmenopausal women and breast cancer detection by means of mammography and breast biopsy

PURPOSE

As the influence of estrogen alone on breast cancer detection is not established, we examined this issue in the Women's Health Initiative trial, which randomly assigned 10,739 postmenopausal women with prior hysterectomy to conjugated equine estrogen (CEE; 0.625 mg/d) or placebo.

METHODS

Screening mammography and breast exams were performed at baseline and annually. Breast biopsies were based on clinical findings. Effects of CEE alone on breast cancer detection were determined by using receiver operating characteristic (ROC) analyses of mammogram performance.

RESULTS

After a 7.1-year mean follow-up, fewer invasive breast cancers were diagnosed in the CEE than in the placebo group, but the difference was not statistically significant. Use of CEE alone increased mammograms with short-interval follow-up recommendations (cumulative, 39.2% v 29.6.3%; P < .001) but not abnormal mammograms (ie, those suggestive of or highly suggestive of malignancy; cumulative, 7.3% v 7.0%; P = .41). Breast biopsies were more frequent in the CEE group (cumulative, 12.5% v 10.7%; P = .004) and less commonly diagnosed as cancer (8.9% v 15.8%, respectively, with positive biopsies; P = .04). Mammographic breast cancer detection in the CEE group was significantly compromised only in the early years of use.

CONCLUSION

CEE alone use for 5 years results in approximately one in 11 and one in 50 women having otherwise avoidable mammograms with short-interval follow-up recommendations or breast biopsies, respectively. Although the breast biopsies on CEE were less commonly diagnosed as cancer, breast cancer detection was not substantially compromised. These findings differ from estrogen-plus-progestin use, for which significantly increased abnormal mammograms and a compromise in breast cancer detection are seen.

Decreased accuracy in interpretation of community-based screening mammography for women with multiple clinical risk factors

OBJECTIVE

To assess the impact of women's breast cancer risk factors (use of hormone therapy, family history of breast cancer, previous breast biopsy) on radiologists' mammographic interpretive performance and whether the influence of risk factors varies according to radiologist characteristics.

STUDY DESIGN AND SETTING

Screening mammograms (n=638,947) performed from 1996 to 2005 by 134 radiologists from three Breast Cancer Surveillance Consortium registries was linked to cancer outcomes, radiologist surveys, and patient questionnaires. Interpretive performance measures were modeled using marginal and conditional logistic regression.

RESULTS

Having one or more clinical risk factors was associated with higher recall rates (1 vs. 0 risk factors: odds ratio [OR]=1.17, 95% confidence interval [CI]=1.15-1.19; > or = 2 vs. 0: OR=1.43, 95% CI=1.40-1.47) and lower specificity (1 vs. 0: OR=0.86 [95% CI=0.84-0.88]; > or = 2 vs. 0: OR=0.70 [95% CI=0.68-0.72]) without a corresponding improvement in sensitivity and only a small increase in positive predictive value (1 vs. 0: OR=1.08 [95% CI=0.99-1.19]; > or = 2 vs. 0: OR=1.12 [95% CI=0.99-1.26]). There was no indication that influence of risk factors varied by radiologist characteristics.

CONCLUSION

Women with clinical risk factors who undergo screening mammography are more likely recalled for false-positive evaluation without an associated increase in cancer detection. Radiologists and patients with risk factors should be aware of this increased risk of adverse screening events.

Cancer issues

The potential for hormone therapy to cause cancer is the greatest fear for postmenopausal women considering hormone replacement therapy (HRT). Breast cancer is the most common female malignancy, for which HRT is one of many modifiable risk factors, often attracting disproportionate attention. Randomized controlled trials have confirmed that in postmenopausal women aged 50-59 years taking combined oestrogen and progestogen HRT over 5 years, there will be three extra cases of breast cancer per 1000 women. With the use of unopposed conjugated equine oestrogens, there would be four fewer cases over the same time. Women can be advised that the risk of breast cancer is not significantly increased with up to 3 years of combined HRT and up to 5 years of unopposed oestrogen. Unopposed oestrogen increases the risk of endometrial hyperplasia and carcinoma significantly, and this is dose and duration dependent. The addition of progestogen prevents the proliferative effect of oestrogen on the endometrium, and may even reduce the risk of endometrial cancer compared with non-users if given continuously. The use of combined oral contraception in premenopausal women also reduces the risk of endometrial cancer but increases the risk of cervical carcinoma significantly. HRT does not influence the risk of cervical cancer. Epithelial ovarian cancer risk may be slightly increased with long-term use of unopposed oestrogen, is not altered by the addition of progestogen, and is reduced significantly in users of combined oral contraception. The mechanism for these effects is not understood. Colorectal cancer and possibly lung and gastric cancers are reduced by the use of HRT. Apart from a slight increased risk of gallbladder disease and carcinoma with HRT, there are no data linking oestrogen or progestogen with any other malignancies.

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.

Is Hormone Replacement Therapy-Related Breast Cancer More Favorable? A Case-Control Study

Hormone replacement therapy (HRT)-related breast cancer may carry a better prognosis since there is no increase in breast cancer deaths. We looked at the prognostic risk factors and outcome inpatients who had ever taken HRT compared to those who had not, in a case control study. Subgroups of recent-users and those using HRT for >5 years were also compared to controls. Tumor size, grade, vascular invasion, lymph node, and estrogen receptor status as well as median Nottingham Prognostic Indicator (NPI) were compared between cases and controls. Absolute survival between ever-users and never-users was compared by life table analysis. There was no difference between all the cases and their controls for the five prognostic factors. NPI in each group was also similar. Absolute survival between ever-users and never-users was not significantly different either (p = 0.678). There was no evidence that HRT-related breast cancer has a more favorable outcome.

The influence of HRT on technical recall in the UK Breast Screening Programme: are pain, compression force, and compressed breast thickness contributing factors?

AIM

To investigate recall for technical reasons within the UK Breast Screening Programme, and to determine whether differences exist in those women using hormone replacement therapy (HRT), considering potential associations with reported pain, compression force used and compressed breast thickness (CBT) obtained.

MATERIALS AND METHOD

A prospective cohort study of 2765 women attending for incident round breast screening appointments who were either HRT users, with a minimum of 1 year duration (n=1077), or had never used HRT (n=1688). Data were collected using technical recall records, a radiographer data-collection sheet, and a self-administered participant questionnaire.

RESULTS

Sixty-eight (2.5%) participants were recalled for technical reasons of whom 28 (2.6%) were HRT and 40 (2.4%) non-HRT users. This difference was not statistically significant (p=0.80). Significant differences were found for CBT between those HRT users who were and were not recalled for technical reasons (p<0.01) and for the similar categories of non-HRT users (p=0.03). No significant differences were found for force between those HRT users who were recalled or not (p=0.73) and for the similar categories of non-HRT users (p=0.07). Similarly no significant differences were found for pain between those HRT users who were recalled or not (p=0.75) and for the similar categories of non-HRT users (p=0.73).

CONCLUSION

CBT was the only variable to have both a statistically and a clinically significant relationship with technical recall.

Influence of Patterns of Hormone Replacement Therapy Use and Mammographic Density on Breast Cancer Detection

BACKGROUND

There is evidence that factors such as current hormone replacement therapy (HRT) use and mammographic density may each lower the sensitivity of mammography and are associated with a greater risk of developing an interval cancer. This study explores this relationship further by examining the influence of patterns of HRT use and the percentage of mammographic density on the detection of breast cancer by classification of interval cancer.

METHODS

This study uses a case-case design nested within a cohort of women screened by the Ontario Breast Screening Program between 1994 and 2002. Interval cancers, both those missed at screening but seen on retrospective review (n = 87) or true intervals without visible tumor signs at screening (n = 288) were matched to 450 screen-detected cancers. The association between the percentage of mammographic density, measured by radiologists and a computer-assisted method, and HRT use, ascertained from a mailed questionnaire, and the risk of being diagnosed with an interval cancer was estimated using conditional logistic regression.

RESULTS

A monotonic gradient of increasing risk for interval cancers was found for each 25% increase in mammographic density [odds ratio (OR), 1.77; 95% confidence intervals (95% CI), 1.07-2.95 for missed intervals and OR, 2.16; 95% CI, 1.59-2.94 for true intervals]. After adjusting for mammographic density, a significantly increased risk for true-interval cancers remained for women taking estrogen alone (OR, 1.75; 95% CI, 1.11-2.83) as well as for missed- (OR, 2.84; 95% CI, 1.32-6.13) and true-interval cancers (OR, 1.79; 95% CI, 1.10-2.90) for women taking combined HRT.

CONCLUSIONS

Information on mammographic density and HRT use should routinely be collected at the time of screening. Women at risk should be made aware of the lower sensitivity of mammography and offered alternative procedures for screening.

The effect of low dose hormone therapy on mammographic breast density

OBJECTIVES

To evaluate the effect of two standard and one low dose continuous hormone therapy regimens on mammography.

METHODS

One hundred and thirty-two non-hysterectomized postmenopausal women were randomly allocated either to conjugated equine estrogens 0.625 mg plus medroxyprogesterone acetate 5 mg (CEE/MPA, n=38), 17beta-estradiol 2 mg plus norethisterone acetate 1 mg (E2/NETA, n=44) or 17beta-estradiol 1 mg plus norethisterone acetate 0.5 mg (low E2/NETA, n=50). Treatment was continuous and the study period lasted 12 months. Main outcome measures were the changes according to Wolfe classification between baseline and 12-month mammograms.

RESULTS

Five (13.2%) women in the CEE/MPA group showed an increase in breast density. Fourteen (31.8%) women on E2/NETA and 6 (12.2%) on low E2/NETA treatment revealed an increase in breast density. No woman exhibited an involution of fibroglandular tissue.

CONCLUSIONS

Different hormone therapy regimens have a variable impact on breast density probably depending on the steroid used. Low dose hormone therapy associates with significantly lesser increase in breast density.

Influence of Hormone Replacement Therapy on the Accuracy of Screening Mammography

The use of hormone replacement therapy (HRT) is currently a subject of debate because of the possibility of an increase in the incidence of breast cancer and difficulties associated with breast cancer detection. The objective of this study was to determine the influence of HRT on specificity and sensitivity in a breast cancer screening program. We found that although specificity was significantly lower in menopausal women who had ever used or were currently using HRT (93.3%) compared to HRT nonusers (94.8%) at the expense of a greater number of recalls (6.9% versus 5.6%), this difference seems to be clinically irrelevant. There were no significant differences with regard to the number of invasive procedures (2.5% in the HRT versus 2.1% in the control group). We conclude that the slight decrease in sensitivity of screening mammography in HRT users is not clinically significant in our setting, and in any case, false positives (recalled women) are diagnosed correctly with additional imaging studies without the need for invasive procedures. Most women given HRT are candidates to participate in population breast cancer screening campaigns.

Postmenopausal hormone therapy and mammographic breast density

OBJECTIVE

The aim of this study was to evaluate the effects of different types of hormone replacement therapy (HRT) on mammographic density.

MATERIALS AND METHODS

In a prospective 1-year study, 103 postmenopausal women were randomized to receive tibolone 2.5 mg/die, continuous conjugated equine estrogens 0.625 mg/die plus medroxyprogesterone acetate (MPA) 5mg/die or placebo. Mammograms were performed at baseline and after 12 months of treatment. Mammographic density was quantified according to the Wolfe classification.

RESULTS

After 12 months of HRT 16 of the 35 patients (45.1%) receiving continuous combined hormonal therapy showed an increase of breast density change in the Wolfe classification. After treatment with tibolone, an up grading in breast density, according to Wolfe's classification, was found in 2 of the 43 patients (2.3%). No changes were recorded in the 25 patients of the control group. The difference between the group treated with continuous combined hormonal therapy and the control group was highly significant (p<0.001). The difference in breast density between patients in treatment with tibolone and the control group was not statistically significant (p=0.34).

DISCUSSION

Continuous combination HRT may be more commonly associated with an increase of mammography density than tibolone treatment.

Use of hormone therapy and risk of breast cancer detected at screening and between mammographic screens

Postmenopausal hormone therapy (HT) is associated with increased risk of breast cancer, but in women undergoing breast cancer screening it is not clear whether use of HT is associated with increased risk of breast cancer detected at screening or between screens (interval cancer). Further, it is unclear whether the use of the HTs that have been common in Scandinavia is associated with higher risk of breast cancer than the HTs used in other countries. Our study was based on data from 296,651 women aged 50-69 years, who participated in the Norwegian Breast Cancer Screening Program during 1995-2004. After a mean enrollment time of 3.8 years, 1,512 women were diagnosed with invasive screen detected breast cancer, and 814 with invasive interval breast cancer. Cox regression models were used to estimate hazard ratios (HRs) of breast cancer associated with HT use, after adjusting for confounders. Ever users of HT had a 58% increased risk of breast cancer, compared to never users. The HRs associated with HT use were 1.45 (95% confidence interval (CI) = 1.29-1.63) for screen detected and 1.89 (95% CI = 1.61-2.23) for interval cancer. The difference between screen detected and interval cancer was statistically significant (p = 0.011). The HR of breast cancer increased with duration of HT use, but significantly more so for interval than for screen detected cancer (use of HT for 5 or more years compared to never use; HR = 2.91, 95% CI = 2.10-4.04 and HR = 1.94, 95% CI = 1.51-2.50, respectively; p = 0.002). The population attributable fraction of breast cancer due to HT use was 19.8% overall. Ever users of HT tended to develop a cancer of lower grade. No other differences in histological tumor characteristics were observed between ever and never users of HT among screen detected or interval cancers. The estimated risks of either breast cancer overall with HT use are higher in Norway than reported in similar studies from the U.S. HT-use is a stronger risk factor for interval cancer than for screen detected cancer. The increased risk of interval cancer, which may partly be due to decreased sensitivity of mammograms in HT users, remains a challenge in breast cancer screening programs.

Hormone replacement therapy and false positive recall in the Million Women Study: patterns of use, hormonal constituents and consistency of effect

INTRODUCTION

Current and recent users of hormone replacement therapy (HRT) have an increased risk of being recalled to assessment at mammography without breast cancer being diagnosed ('false positive recall'), but there is limited information on the effects of different patterns of HRT use on this. The aim of this study is to investigate in detail the relationship between patterns of use of HRT and false positive recall.

METHODS

A total of 87,967 postmenopausal women aged 50 to 64 years attending routine breast cancer screening at 10 UK National Health Service Breast Screening Units from 1996 to 1998 joined the Million Women Study by completing a questionnaire before screening and were followed for their screening outcome.

RESULTS

Overall, 399 (0.5%) participants were diagnosed with breast cancer and 2,629 (3.0%) had false positive recall. Compared to never users of HRT, the adjusted relative risk (95% CI) of false positive recall was: 1.62 (1.43-1.83), 1.80 (1.62-2.01) and 0.76 (0.52-1.10) in current users of oestrogen-only HRT, oestrogen-progestagen HRT and tibolone, respectively (p (heterogeneity) < 0.0001); 1.65 (1.43-1.91), 1.49 (1.22-1.81) and 2.11 (1.45-3.07) for current HRT used orally, transdermally or via an implant, respectively (p (heterogeneity) = 0.2); and 1.84 (1.67-2.04) and 1.75 (1.49-2.06) for sequential and continuous oestrogen-progestagen HRT, respectively (p (heterogeneity) = 0.6). The relative risk of false positive recall among current users appeared to increase with increasing time since menopause, but did not vary significantly according to any other factors examined, including duration of use, hormonal constituents, dose, whether single- or two-view screening was used, or the woman's personal characteristics.

CONCLUSION

Current use of oestrogen-only and oestrogen-progestagen HRT, but not tibolone, increases the risk of false positive recall at screening.

Breast cancer risk in relation to different types of hormone replacement therapy in the E3N-EPIC cohort

Most epidemiological studies have shown an increase in breast cancer risk related to hormone replacement therapy (HRT) use. A recent large cohort study showed effects of similar magnitude for different types of progestogens and for different routes of administration of estrogens evaluated. Further investigation of these issues is of importance. We assessed the risk of breast cancer associated with HRT use in 54,548 postmenopausal women who had never taken any HRT 1 year before entering the E3N-EPIC cohort study (mean age at inclusion: 52.8 years); 948 primary invasive breast cancers were diagnosed during follow-up (mean duration: 5.8 years). Data were analyzed using multivariate Cox proportional hazards models. In this cohort where the mean duration of HRT use was 2.8 years, an increased risk in HRT users compared to nonusers was found (relative risk (RR) 1.2 [95% confidence interval 1.1-1.4]). The RR was 1.1 [0.8-1.6] for estrogens used alone and 1.3 [1.1-1.5] when used in combination with oral progestogens. The risk was significantly greater (p <0.001) with HRT containing synthetic progestins than with HRT containing micronized progesterone, the RRs being 1.4 [1.2-1.7] and 0.9 [0.7-1.2], respectively. When combined with synthetic progestins, both oral and transdermal/percutaneous estrogens use were associated with a significantly increased risk; for transdermal/percutaneous estrogens, this was the case even when exposure was less than 2 years. Our results suggest that, when combined with synthetic progestins, even short-term use of estrogens may increase breast cancer risk. Micronized progesterone may be preferred to synthetic progestins in short-term HRT. This finding needs further investigation.

Strategies for managing breast cancer risk after the menopause

Postmenopausal women in Western societies are conscious of breast cancer as a potential cause of death and ill health, which they wish to avoid with the advice of their doctors. Yet many factors that predispose women to the development of cancer will have been laid down before the menopause, in their genetic makeup or during their adolescent years. Even in middle age it is important to take account of the intrinsic level of risk, and to give women advice tailored to their own individual risk level. This results from their family history, previous diseases such as benign breast disease, and previous treatment for breast cancer or Hodgkin's disease. For those at the highest level of risk, strategies will include regular screening, prophylactic mastectomy, and the use of chemoprevention agents, such as tamoxifen. These women should avoid hormone replacement therapy (HRT) and control their menopausal symptoms and osteoporosis through the use of other agents now available - venlafaxine for menopausal symptoms and bisphosphonates for osteoporosis. Raloxifene is an agent under trial that may be valuable for breast cancer control as well as for osteoporosis. Women at standard population risk will require less robust preventive strategies, which will include screening and lifestyle modification. Their decisions regarding HRT should now be modified by recent evidence of associated risks. Recent studies show that tibolone causes less mammographic density and has a lower relative risk of breast cancer than combined estrogen/progestogen preparations. There is limited evidence that controlling obesity, participating in exercise and adopting a diet low in fats and high in fruit and vegetables will alter risk at this age. These precautions will, however, reduce the risk of other diseases common in this age group, such as hypertension, heart disease, stroke, and type 2 diabetes mellitus. Alcohol, even in small amounts, is a risk factor for breast cancer. Given the cardioprotective effect of moderate alcohol intake, advice on alcohol must reflect the individual relative risk of cardiovascular disease and breast cancer. Personal risk assessment is relevant for all women. Screening and a healthy lifestyle are worthwhile approaches for all, with the more aggressive approaches such as chemoprevention and prophylactic surgery reserved for those who have substantially elevated levels of risk. Once the menopause has passed, screening is probably the most effective evidence-based tool for breast cancer control by early diagnosis.

Influence of different HRT regimens on mammographic density

OBJECTIVES

A prospective, randomized, open-label study was conducted to evaluate effects on mammographic density in postmenopausal and late perimenopausal women receiving continuous combined or sequential combined hormone replacement therapy (HRT).

METHODS

The subjects were randomized to treatment with low-dose continuous combined HRT containing 1 mg 17beta-estradiol plus 0.5 mg norethisterone acetate (Activelle) or a sequential combined HRT regimen consisting of 0.625 mg conjugated equine estrogens for 28 days plus 5 mg medrogestone for 14 days (Presomen). Mammograms were obtained at baseline and after 9 cycles (each 28 days) of treatment.

RESULTS

The majority of women (approximately two-thirds in each treatment group) had no changes in mammographic breast density between baseline and the final study visit. There were no marked differences between treatment groups. Approximately 20% of women in both groups had a slight increase in mammographic density. Only 10-14% of women in both groups had a pronounced increase in mammographic density. The analyses of the degree of change showed no remarkable differences between treatments.

CONCLUSION

These results indicate that the increase in mammographic density with a low-dose continuous combined HRT regimen is no greater than that with a sequential combined HRT regimen. The type of progestogen does not have an impact on the extent of mammographic density changes.

Long-term effects of tibolone on mammographic density

OBJECTIVE

To investigate the long-term effect of tibolone on mammographic density.

DESIGN

Open-label, nonrandomized study.

SETTING

Academic research environment.

PATIENT(S)

Postmenopausal women.

INTERVENTION(S)

Tibolone was administered orally, mammograms were performed annually.

MAIN OUTCOME MEASURE(S)

Mammographic density according to the Wolfe classification, performed by two independent radiologists, both of whom were blinded to treatment group.

RESULT(S)

No statistically significant differences were found between the two groups in baseline demographic data. There were no statistically significant differences in mammographic density between the control and active groups at baseline or at 10 years.

CONCLUSION(S)

This pilot study shows that tibolone does not adversely alter the mammographic density of the breasts over 10 years of treatment.

Breast screening outcomes in women with and without a family history of breast and/or ovarian cancer

OBJECTIVES

To compare breast screening outcomes between women with a moderate or strong family history of breast and/or ovarian cancer with those without such a history.

SETTING

The Ontario Breast Screening Programme (OBSP) is a population-based programme offering mammography and clinical breast examination to Ontario women of 50 and older.

METHODS

Data from a cohort of 143,574 women screened by the OBSP from 1996 to 1997 were included. Referral rates, cancer detection rates, positive predictive values and the histological features of screen-detected cancers were examined within family history groups, age groups and screening modalities. Logistic regression analysis of cancer detection was conducted to adjust for potential confounding variables; subgroup analysis by hormone replacement therapy (HRT) use was also undertaken.

RESULTS

Compared with women with no family history, women with a moderate or strong family history of breast and/or ovarian cancer were more likely to have their cancer detected (odds ratio [OR]=1.44, 95% confidence interval [CI] 1.20-1.74 and OR=1.42, 95% CI 1.10-1.83, respectively). Among women using HRT, however, there was no association observed between family history and cancer detection (moderate: OR=0.98, 95% CI 0.65-1.48; strong: OR=1.17, 95% CI 0.68-2.02) with history. The histological features of invasive tumours were similar among family history groups.

CONCLUSIONS

Greater cancer detection rates and high proportions of invasive tumours with good prognosis indicate that women aged 50 and over with a family history may have the potential to benefit from regular breast cancer screening. Further studies are required to identify optimal screening guidelines and to examine whether HRT reduces the ability to detect cancer in these women.

Postmenopausal hormone therapy and the risk of breast cancer

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

Hormones and mammographic breast density

Mammographic density reveals information about the hormonal environment along with the heritability in which breast cancer develops. This is made possible by the widespread use of population screening by mammography. Increasingly this is an important observation not just for population studies, which reveal disease determinants, but also for the individual. Density reveals the effect of the intrinsic hormonal environment and its background genetics, and also the effect of pharmaceuticals--agents used for disease control and prevention and hormone replacement therapy (HRT) used for well-being around the menopause. Increasingly this focus on the individual will need methods of measurement of density that can be monitored with greater accuracy than the widely used BI-RADS 4 categories. For this purpose studies are under way to measure volume of dense tissue as a continuous variable. In due course, measurement of density will be used as a biomarker of risk, employed in risk models and to monitor interventions. Before this can happen more knowledge will be needed of the change occurring naturally through the menopause and the differences between individuals. This will need specific study backed up with detailed information about the patient on large numbers of women and their mammograms. Currently the widespread use of HRT has increased the prevalence of the dense patterns and potentially may adversely affect the effectiveness of mammographic screening programmes. There is a large literature recording this from which we see that combined continuous preparations of oestrogen progestin are more likely to cause increased density than oestrogen alone or tibolone. Breast density, measured more accurately, has the potential to be an important adjunct to risk estimation and to monitor interventions for breast cancer prevention with pharmaceuticals (such as SERMS) and by change in lifestyle behaviours.

Influence of personal characteristics of individual women on sensitivity and specificity of mammography in the Million Women Study: cohort study

OBJECTIVES

To examine how lifestyle, hormonal, and other factors influence the sensitivity and specificity of mammography.

METHODS

Women recruited into the Million Women Study completed a questionnaire about various personal factors before routine mammographic screening. A sample of 122,355 women aged 50-64 years were followed for outcome of screening and incident breast cancer in the next 12 months. Sensitivity and specificity were calculated by using standard definitions, with adjustment for potential confounding factors.

RESULTS

Breast cancer was diagnosed in 726 (0.6%) women, 629 in screen positive and 97 in screen negative women; 3885 (3.2%) were screen positive but had no subsequent diagnosis of breast cancer. Overall sensitivity was 86.6% and specificity was 96.8%. Three factors had an adverse effect on both measures: use of hormone replacement therapy (sensitivity: 83.0% (95% confidence interval 77.4% to 87.6%), 84.7% (73.9% to 91.6%), and 92.1% (87.6% to 95.0%); specificity: 96.8% (96.6% to 97.0%), 97.8% (97.5% to 98.0%), and 98.1% (98.0% to 98.2%), respectively, for current, past, and never use); previous breast surgery v no previous breast surgery (sensitivity: 83.5% (75.7% to 89.1%) v 89.4% (86.5% to 91.8%); specificity: 96.2% (95.8% to 96.5%) v 97.4% (97.3% to 97.5%), respectively); and body mass index < 25 v > or = 25 (sensitivity: 85.7% (81.2% to 89.3%) v 91.0% (87.5% to 93.6%); specificity: 97.2% (97.0% to 97.3%) v 97.4% (97.3% to 97.6%), respectively). Neither sensitivity nor specificity varied significantly according to age, family history of breast cancer, parity, past oral contraceptive use, tubal ligation, physical activity, smoking, or alcohol consumption.

CONCLUSIONS

The efficiency, and possibly the effectiveness, of mammographic screening is lower in users of hormone replacement therapy, in women with previous breast surgery, and in thin women compared with other women.

Estrogen receptor beta inhibits human breast cancer cell proliferation and tumor formation by causing a G2 cell cycle arrest

Studies indicate that estrogen receptor (ER) alpha mediates breast cancer-promoting effects of estrogens. The role of ERbeta in breast cancer is unknown. Elucidating the role of ERbeta in the pathogenesis of breast cancer is important because many human breast tumors express both ERalpha and ERbeta. We show that adenovirus-mediated expression of ERbeta changes the phenotype of ERalpha-positive MCF-7 cells. Estradiol increases cell proliferation and causes tumor formation of MCF-7 cells expressing only ERalpha. In contrast, introducing ERbeta into MCF-7 cells causes an inhibition of proliferation in vitro and prevents tumor formation in a mouse xenograft model in response to estradiol. ERbeta inhibits proliferation by repressing c-myc, cyclin D1, and cyclin A gene transcription, and increasing the expression of p21(Cip1) and p27(Kip1), which leads to a G(2) cell cycle arrest. These results demonstrate that ERalpha and ERbeta produce opposite effects in MCF-7 cells on cell proliferation and tumor formation. Natural or synthetic ERbeta-selective estrogens may lack breast cancer promoting properties exhibited by estrogens in hormone replacement regimens and may be useful for chemoprevention of breast cancer.

Changes in magnetic resonance mammography due to hormone replacement therapy

Background

The aim of the present article is to investigate effects of hormone replacement therapy (HRT) on contrast medium enhancement patterns in postmenopausal patients during magnetic resonance mammography (MRM).

Materials and methods

Two hundred and fifteen patients receiving hormonal medication were divided into four groups: 150 patients with 1 MRM during HRT (group A), 13 patients with 2 MRMs under HRT (group B), 30 patients with 1 MRM during HRT and 1 MRM after HRT withdrawal (group C), and 22 women with 1 MRM after HRT withdrawal (group D). Dynamic MRM was performed at 1.5 Tesla. Signal intensity changes were characterized by five time curves: minimal enhancement (type I), weak continuous enhancement (type II), strong continuous enhancement (type III), and a steep initial slope followed by a plateau phenomenon (type IV) or a washout effect (type V).

Results

Of all 193 patients under HRT (group A + group B + group C), 60 patients (31.1%) showed curve type I, 88 patients (45.6%) showed type II and 45 patients (23.3%) showed type III. There were significant differences to 52 patients after HRT withdrawal (group C + group D) (P < 0.0001), with 42 patients (80.8%) for curve type I, 8 patients (15.4%) for type II, and 2 patients (3.8%) for type III. In both MRM sessions in group B, 69% of the patients showed identical curve types without significant differences (P = 0.375). In group C, 28 of 30 patients (93%) dropped to lower curve types with significant differences in curve types during and after HRT (P < 0.0001).

Conclusion

The majority of patients receiving postmenopausal HRT showed bilateral symmetrical, continuous enhancement without evidence of a plateau phenomenon or a washout effect due to HRT in MRM. Hormonal effects could be proven and were reproducible and reversible.

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

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

METHODS

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

RESULTS

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

CONCLUSION

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

Political interpretation of scientific evidence--case study of breast cancer screening policies around the world

Early detection of breast cancer has been studied for effectiveness in reducing mortality for more than four decades. During this period numerous studies took place, with more than half a million participating women. In spite of large amounts of nonconflicting data, different countries took varying lengths of time to establish a policy, and came up with a variety of policies, quite different from one another. Inherent differences between the countries in structure of the health system, in the commitment to public health activities, and in opinions and health habits of the relevant populations may explain these different outcomes.

Breast cancer and hormone-replacement therapy in the Million Women Study

BACKGROUND

Current use of hormone-replacement therapy (HRT) increases the incidence of breast cancer. The Million Women Study was set up to investigate the effects of specific types of HRT on incident and fatal breast cancer.

METHODS

1084110 UK women aged 50-64 years were recruited into the Million Women Study between 1996 and 2001, provided information about their use of HRT and other personal details, and were followed up for cancer incidence and death.

FINDINGS

Half the women had used HRT; 9364 incident invasive breast cancers and 637 breast cancer deaths were registered after an average of 2.6 and 4.1 years of follow-up, respectively. Current users of HRT at recruitment were more likely than never users to develop breast cancer (adjusted relative risk 1.66 [95% CI 1.58-1.75], p<0.0001) and die from it (1.22 [1.00-1.48], p=0.05). Past users of HRT were, however, not at an increased risk of incident or fatal disease (1.01 [0.94-1.09] and 1.05 [0.82-1.34], respectively). Incidence was significantly increased for current users of preparations containing oestrogen only (1.30 [1.21-1.40], p<0.0001), oestrogen-progestagen (2.00 [1.88-2.12], p<0.0001), and tibolone (1.45 [1.25-1.68], p<0.0001), but the magnitude of the associated risk was substantially greater for oestrogen-progestagen than for other types of HRT (p<0.0001). Results varied little between specific oestrogens and progestagens or their doses; or between continuous and sequential regimens. The relative risks were significantly increased separately for oral, transdermal, and implanted oestrogen-only formulations (1.32 [1.21-1.45]; 1.24 [1.11-1.39]; and 1.65 [1.26-2.16], respectively; all p<0.0001). In current users of each type of HRT the risk of breast cancer increased with increasing total duration of use. 10 years' use of HRT is estimated to result in five (95% CI 3-7) additional breast cancers per 1000 users of oestrogen-only preparations and 19 (15-23) additional cancers per 1000 users of oestrogen-progestagen combinations. Use of HRT by women aged 50-64 years in the UK over the past decade has resulted in an estimated 20000 extra breast cancers, 15000 associated with oestrogen-progestagen; the extra deaths cannot yet be reliably estimated.

INTERPRETATION

Current use of HRT is associated with an increased risk of incident and fatal breast cancer; the effect is substantially greater for oestrogen-progestagen combinations than for other types of HRT.

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.

Impact of false-positive mammography on subsequent screening attendance and risk of cancer

BACKGROUND

One area of concern within the largely successful UK National Health Service breast screening programme is the relatively high proportion of women showing mammographic abnormalities who undergo further diagnostic tests that prove negative. Previous studies suggest that, in addition to increasing anxiety, such false-positive mammography is associated with increased risk of subsequent interval cancer. In the present article, we quantify this increased risk, investigate whether it extends to cancers detected at rescreening, and determine whether cancers differ between women who have, and have not, experienced false-positive mammography.

METHODS

This was a retrospective cohort study of 140,387 women aged 49-63 years routinely invited for first screening by the East Anglian National Health Service breast screening programme. Proportions reattending, and subsequent risk and pathological attributes of cancer were compared between women who underwent further (negative) assessment following false-positive mammography and women mammographically normal at first screen.

RESULTS

At first screen, 108,617 (91.9%) of the screened women were mammographically normal, 4278 (3.6%) were assessed and then judged normal, and 514 (0.4%) underwent benign biopsy. Compared with nonassessed normal women, reattendance was lower among assessed women: 83.1% (95% confidence interval [CI], 82.0-84.1) versus 85.7% (95% CI, 85.5-85.9) (odds ratio [OR], 0.82; 95% CI, 0.76-0.89). Assessed women were at greater risk of interval cancer (rate per 1000 women screened, 9.6 [95% CI, 6.8-12.4] versus 3.0 [95% CI, 2.7-3.4]; OR, 3.19 [95% CI, 2.34-4.35]), and also of cancer detected at second screen (rate per 1000, 8.4 [95% CI, 5.8-10.9] versus 3.9 [95% CI, 3.5-4.3]; OR, 2.15 [95% CI, 1.55-2.98]). More cancers in assessed women measured >or = 20 mm (OR, 1.59; 95% CI, 0.99-2.55).

CONCLUSIONS

Women undergoing false-positive mammography at first screen were less likely to reattend for subsequent screens than were nonassessed women, yet they were more likely to develop interval cancers or cancers at second screen, and their cancers were larger. Factors predisposing for false-positive mammography require investigation. Women should be encouraged to continue with screening.

Mammographic changes associated with raloxifene and tibolone therapy in postmenopausal women: a prospective study

OBJECTIVE

The prolonged use of estrogen therapy is associated with a slightly increased risk of breast cancer. Alternative therapies that are effective in the prevention of menopause, having associated morbidities but no unwanted effects, are of primary interest in the pharmacologic research. The aim of this study was to evaluate the effect of two alternative to estrogens drugs, the selective estrogen receptor modulator raloxifene and the tissue-specific tibolone, on the mammographic appearance of the breast.

DESIGN

The study group comprised 131 postmenopausal women aged 41 to 67 years. The women were at least 2 years postmenopausal, free of climacteric symptoms, and at the time of entry to the study had not had therapy for at least 9 months. Women with risk factors for osteoporosis or cardiovascular disease were allocated either to tibolone (n = 56) or raloxifene (n = 48) therapy. Women with no risk factors and women who either did not qualify for or denied treatment (n = 27) served as controls. The study duration was 12 months. Women received a baseline mammogram before commencing therapy and a repeat mammogram at the end of the study period. Mammogram findings were classified according to the modified Wolfe criteria by two expert radiologists.

RESULTS

No difference was identified between groups with respect to baseline characteristics associated with breast cancer risk. Similarly, no difference was detected between groups concerning the modified Wolfe classification of baseline mammographic findings. In the tibolone group, 10.7% of the women showed an increase in breast density in the 12-month reevaluation. The respective figure in the raloxifene group was 6.3%, whereas no woman in the control group showed an increase in breast density. Differences in the increase in breast density between groups did not, however, reach statistical significance. Accordingly, 10.7% of women in the tibolone group and 18.8% of women in the raloxifene group exhibited involutionary changes in the repeat mammogram, whereas 25.9% of women in the control group revealed a decrease in breast density in the 12-month examination. The percentages were not significantly different between groups.

CONCLUSIONS

Breast density as shown by mammography was stable in a majority of patients and changed in a minority of cases for both tibolone and raloxifene. In most patients, these drugs are not likely to interfere with mammogram interpretation. Larger long-term studies are needed to confirm the impact of prolonged tibolone or raloxifene administration on mammography.