Mammographic densities and the prevalence and incidence of histological types of benign breast disease. Reference Pathologists of the Canadian National Breast Screening Study

Benign breast disease and changes in mammographic breast density

Background

Mammographic breast density (MBD) and benign breast disease (BBD) are two of the strongest risk factors for breast cancer. Understanding trends in MBD by age and parity in women with BBD is essential to the clinical management and prevention of breast cancer.

Methods

Using data from the Early Determinants of Mammographic Density (EDMD) study, a prospective follow-up study of women born in 1959–1967, we evaluated MBD in 676 women. We used linear regression with generalized estimating equations to examine associations between self-reported BBD and MBD (percent density, dense area, and non-dense area), assessed through a computer-assisted method.

Results

A prior BBD diagnosis (median age at diagnosis 32 years) was reported by 18% of our cohort. The median time from BBD diagnosis to first available study mammogram was 9.4 years (range 1.1–27.6 years). Women with BBD had a 3.44% higher percent MBD (standard error (SE) = 1.56, p-value = 0.03) on their first available mammogram than women without BBD. Compared with parous women without BBD, nulliparous women with BBD and women with a BBD diagnosis prior to first birth had 7–8% higher percent MBD (β = 7.25, SE = 2.43, p-value< 0.01 and β = 7.84, SE = 2.98, p-value = 0.01, respectively), while there was no difference in MBD in women with a BBD diagnosis after the first birth (β = −0.22, SE = 2.40, p-value = 0.93).

Conclusion

Women with self-reported BBD had higher mammographic breast density than women without BBD; the association was limited to women with BBD diagnosed before their first birth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01426-7.

Stiff stroma increases breast cancer risk by inducing the oncogene ZNF217

Women with dense breasts have an increased lifetime risk of malignancy that has been attributed to a higher epithelial density. Quantitative proteomics, collagen analysis, and mechanical measurements in normal tissue revealed that stroma in the high-density breast contains more oriented, fibrillar collagen that is stiffer and correlates with higher epithelial cell density. microRNA (miR) profiling of breast tissue identified miR-203 as a matrix stiffness-repressed transcript that is downregulated by collagen density and reduced in the breast epithelium of women with high mammographic density. Culture studies demonstrated that ZNF217 mediates a matrix stiffness- and collagen density-induced increase in Akt activity and mammary epithelial cell proliferation. Manipulation of the epithelium in a mouse model of mammographic density supported a causal relationship between stromal stiffness, reduced miR-203, higher levels of the murine homolog Zfp217, and increased Akt activity and mammary epithelial proliferation. ZNF217 was also increased in the normal breast epithelium of women with high mammographic density, correlated positively with epithelial proliferation and density, and inversely with miR-203. The findings identify ZNF217 as a potential target toward which preexisting therapies, such as the Akt inhibitor triciribine, could be used as a chemopreventive agent to reduce cancer risk in women with high mammographic density.

A review of the influence of mammographic density on breast cancer clinical and pathological phenotype

PURPOSE

It is well established that high mammographic density (MD), when adjusted for age and body mass index, is one of the strongest known risk factors for breast cancer (BC), and also associates with higher incidence of interval cancers in screening due to the masking of early mammographic abnormalities. Increasing research is being undertaken to determine the underlying histological and biochemical determinants of MD and their consequences for BC pathogenesis, anticipating that improved mechanistic insights may lead to novel preventative or treatment interventions. At the same time, technological advances in digital and contrast mammography are such that the validity of well-established relationships needs to be re-examined in this context.

METHODS

With attention to old versus new technologies, we conducted a literature review to summarise the relationships between clinicopathologic features of BC and the density of the surrounding breast tissue on mammography, including the associations with BC biological features inclusive of subtype, and implications for the clinical disease course encompassing relapse, progression, treatment response and survival.

RESULTS AND CONCLUSIONS

There is reasonable evidence to support positive relationships between high MD (HMD) and tumour size, lymph node positivity and local relapse in the absence of radiotherapy, but not between HMD and LVI, regional relapse or distant metastasis. Conflicting data exist for associations of HMD with tumour location, grade, intrinsic subtype, receptor status, second primary incidence and survival, which need further confirmatory studies. We did not identify any relationships that did not hold up when data involving newer imaging techniques were employed in analysis.

The hypoxic tumour microenvironment

Cancer progression often benefits from the selective conditions present in the tumour microenvironment, such as the presence of cancer-associated fibroblasts (CAFs), deregulated ECM deposition, expanded vascularisation and repression of the immune response. Generation of a hypoxic environment and activation of its main effector, hypoxia-inducible factor-1 (HIF-1), are common features of advanced cancers. In addition to the impact on tumour cell biology, the influence that hypoxia exerts on the surrounding cells represents a critical step in the tumorigenic process. Hypoxia indeed enables a number of events in the tumour microenvironment that lead to the expansion of aggressive clones from heterogeneous tumour cells and promote a lethal phenotype. In this article, we review the most relevant findings describing the influence of hypoxia and the contribution of HIF activation on the major components of the tumour microenvironment, and we summarise their role in cancer development and progression.

Breast density: why all the fuss?

The term "breast density" or mammographic density (MD) denotes those components of breast parenchyma visualised at mammography that are denser than adipose tissue. MD is composed of a mixture of epithelial and stromal components, notably collagen, in variable proportions. MD is most commonly assessed in clinical practice with the time-honoured method of visual estimation of area-based percent density (PMD) on a mammogram, with categorisation into quartiles. The computerised semi-automated thresholding method, Cumulus, also yielding area-based percent density, is widely used for research purposes; however, the advent of fully automated volumetric methods developed as a consequence of the widespread use of digital mammography (DM) and yielding both absolute and percent dense volumes, has resulted in an explosion of interest in MD recently. Broadly, the importance of MD is twofold: firstly, the presence of marked MD significantly reduces mammographic sensitivity for breast cancer, even with state-of-the-art DM. Recognition of this led to the formation of a powerful lobby group ('Are You Dense') in the US, as a consequence of which 32 states have legislated for mandatory disclosure of MD to women undergoing mammography. Secondly, it is now widely accepted that MD is in itself a risk factor for breast cancer, with a four-to sixfold increased relative risk in women with PMD in the highest quintile compared to those with PMD in the lowest quintile. Consequently, major research efforts are underway to assess whether use of MD could provide a major step forward towards risk-adapted, personalised breast cancer prevention, imaging, and treatment.

Association between mammographic breast density and histologic features of benign breast disease

BACKGROUND

Over 40% of women undergoing breast screening have mammographically dense breasts. Elevated mammographic breast density (MBD) is an established breast cancer risk factor and is known to mask tumors within the dense tissue. However, the association of MBD with high risk benign breast disease (BBD) is unknown.

METHOD

We analyzed data for 3400 women diagnosed with pathologically confirmed BBD in the Mayo Clinic BBD cohort from 1985-2001, with a clinical MBD measure (either parenchymal pattern (PP) or Breast Imaging Reporting and Data Systems (BI-RADS) density) and expert pathology review. Risk factor information was collected from medical records and questionnaires. MBD was dichotomized as dense (PP classification P2 or DY, or BI-RADS classification c or d) or non-dense (PP classification N1 or P1, or BI-RADS classification a or b). Associations of clinical and histologic characteristics with MBD were examined using logistic regression analysis to estimate odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

Of 3400 women in the study, 2163 (64%) had dense breasts. Adjusting for age and body mass index (BMI), there were positive associations of dense breasts with use of hormone therapy (HT), lack of lobular involution, presence of atypical lobular hyperplasia (ALH), histologic fibrosis, columnar cell hyperplasia/flat epithelia atypia (CCH/FEA), sclerosing adenosis (SA), cyst, usual ductal hyperplasia, and calcifications. In fully adjusted multivariate models, HT (1.3, 95% CI 1.1-1.5), ALH (1.5, 95% CI 1.0-2.2), lack of lobular involution (OR 1.6, 95% CI 1.2-2.1, compared to complete involution), fibrosis (OR 2.2, 95% CI 1.9-2.6) and CCH/FEA (OR 1.3, 95% CI 1.0-1.6) remained significantly associated with high MBD.

CONCLUSION

Our findings support an association between high risk BBD and high MBD, suggesting that risks associated with the latter may act early in breast carcinogenesis.

Aromatase expression in atypical ductal hyperplasia in women

PURPOSE

To determine the levels of aromatase in atypical ductal hyperplasia (ADH) lesions, tissue surrounding the ADH, and in dense and non-dense normal breast tissue. We postulated that excess aromatase in breast tissue might, through production of increased estrogen, drive the carcinogenic process. Estrogens and their metabolites are thought to contribute to the development of breast cancer through estrogen receptor-mediated mechanisms and genotoxic effects of estrogen metabolites. ADH is a benign lesion of the breast which is associated with substantially increased risk for subsequent development of breast cancer. After 25 years, approximately 30% of women with ADH develop breast cancer. In women with three or more separate ADH lesions at the same time, 47% will develop breast cancer over that time period. Another important risk factor for breast cancer is the presence of mammographically dense breast tissue.

METHODS

We utilized quantitative immunochemical analysis of aromatase in biopsy tissue to test this possibility. Previously published results comparing dense with non-dense breast tissue in normal women (Vachon et al. Breast Cancer Res Treat 125:243-252, 2011) were used for comparisons with ADH. A well-characterized histochemical H-score was employed for quantitative assessment of aromatase in the various tissue studied.

RESULTS

The H-score of aromatase staining was statistically significantly higher (p = 0.003) in the ADH epithelium than surrounding epithelial tissue. In order of H-score from highest to lowest were ADH, issue surrounding ADH, dense normal and non-dense normal breast tissues. The levels of aromatase in a subset of women with ADH who went on to develop breast cancer were not higher than in women who did not.

CONCLUSIONS

We suggest from these studies that overexpression of aromatase in breast tissue and its resultant increase in estradiol levels may contribute to the later development of breast cancer in women with ADH.

Polymorphisms in the estrogen receptor alpha gene (ESR1), daily cycling estrogen and mammographic density phenotypes

Background

Single nucleotide polymorphisms (SNPs) involved in the estrogen pathway and SNPs in the estrogen receptor alpha gene (ESR1 6q25) have been linked to breast cancer development, and mammographic density is an established breast cancer risk factor. Whether there is an association between daily estradiol levels, SNPs in ESR1 and premenopausal mammographic density phenotypes is unknown.

Methods

We assessed estradiol in daily saliva samples throughout an entire menstrual cycle in 202 healthy premenopausal women in the Norwegian Energy Balance and Breast Cancer Aspects I study. DNA was genotyped using the Illumina Golden Gate platform. Mammograms were taken between days 7 and 12 of the menstrual cycle, and digitized mammographic density was assessed using a computer-assisted method (Madena). Multivariable regression models were used to study the association between SNPs in ESR1, premenopausal mammographic density phenotypes and daily cycling estradiol.

Results

We observed inverse linear associations between the minor alleles of eight measured SNPs (rs3020364, rs2474148, rs12154178, rs2347867, rs6927072, rs2982712, rs3020407, rs9322335) and percent mammographic density (p-values: 0.002–0.026), these associations were strongest in lean women (BMI, ≤23.6 kg/m^2.). The odds of above-median percent mammographic density (>28.5 %) among women with major homozygous genotypes were 3–6 times higher than those of women with minor homozygous genotypes in seven SNPs. Women with rs3020364 major homozygous genotype had an OR of 6.46 for above-median percent mammographic density (OR: 6.46; 95 % Confidence Interval 1.61, 25.94) when compared to women with the minor homozygous genotype. These associations were not observed in relation to absolute mammographic density. No associations between SNPs and daily cycling estradiol were observed. However, we suggest, based on results of borderline significance (p values: 0.025–0.079) that the level of 17β-estradiol for women with the minor genotype for rs3020364, rs24744148 and rs2982712 were lower throughout the cycle in women with low (<28.5 %) percent mammographic density and higher in women with high (>28.5 %) percent mammographic density, when compared to women with the major genotype.

Conclusion

Our results support an association between eight selected SNPs in the ESR1 gene and percent mammographic density. The results need to be confirmed in larger studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2804-1) contains supplementary material, which is available to authorized users.

Mammographic density and breast cancer risk: a mediation analysis

BACKGROUND

High mammographic density (MD) is a strong risk factor for breast cancer. However, it is unclear whether high MD is an intermediate phenotype or whether breast cancer risk factors influence breast cancer risk and MD independently.

METHODS

Our study population included 1290 invasive breast cancer cases and 3422 controls from the Nurses' Health Studies. We estimated the percent of the total association between the risk factor and breast cancer that was mediated by MD.

RESULTS

In both pre- and postmenopausal women, the association between history of biopsy-confirmed benign breast disease and risk was partially mediated by percent MD (percent mediated (PM) = 17 %, p < 0.01 and PM = 33 %, p = 0.04, respectively). In premenopausal women, the associations between early life body size (adolescent somatotype and BMI at age 18) and breast cancer risk were substantially mediated by percent MD (PM = 73 %, p = 0.05 and PM = 82 %, p = 0.04, respectively). In postmenopausal women, the proportion of the associations of childhood somatotype and adolescent somatotype that were mediated by percent MD were lower (PM = 26 %, p = 0.01 for both measures). Hormone therapy use at mammogram was significantly mediated by percent MD in postmenopausal women (PM = 22 %, p < 0.01). Associations with other risk factors, such as age at menarche or family history of breast cancer, were not mediated by percent MD.

CONCLUSIONS

Percent MD partially mediated some of the associations between risk factors and breast cancer, though the magnitude varied by risk factor and menopausal status. These findings suggest that high MD may be an intermediate in some biological pathways for breast cancer development.

Reproductive and lifestyle risk factors and mammographic density in Mexican women

PURPOSE

Several breast cancer risk factors have been consistently associated with mammographic density (MD); however, data are limited for Hispanic women.

METHODS

We examined data from 1007 premenopausal and 600 postmenopausal women in the Mexican Teachers' Cohort. Multivariable linear regression was used to estimate associations between risk factors and MD.

RESULTS

Among premenopausal women, age, current body mass index (BMI), BMI at age 18 years, and weight change since age 18 years were inversely associated with percent MD, whereas benign breast disease, alcohol intake, and breastfeeding 12 months or more were associated with higher percent MD. Among postmenopausal women, age, current BMI, BMI at age 18 years, weight change since age 18 years, and speaking or having parents who speak an indigenous language were inversely associated with percent MD, whereas benign breast disease and greater age at natural menopause were positively associated with percent MD. Other breast cancer risk factors, such as age at menarche, parity, and age at first pregnancy, were not significantly associated with density in either premenopausal or postmenopausal women.

CONCLUSIONS

Results from the Mexican Teachers' Cohort are generally consistent with predictors of mammographic density observed in primarily non-Hispanic white populations; however, certain risk factors (e.g., parity) were not significantly associated with MD.

Aromatase overexpression in dysfunctional adipose tissue links obesity to postmenopausal breast cancer

The number of breast cancer cases has increased in the last a few decades and this is believed to be associated with the increased prevalence of obesity worldwide. The risk of breast cancer increases with age beyond menopause and the relationship between obesity and the risk of breast cancer in postmenopausal women is well established. The majority of postmenopausal breast cancers are estrogen receptor (ER) positive and estrogens produced in the adipose tissue promotes tumor formation. Obesity results in the secretion of inflammatory factors that stimulate the expression of the aromatase enzyme, which converts androgens into estrogens in the adipose tissue. Evidence demonstrating a link between obesity and breast cancer has led to the investigation of metabolic pathways as novel regulators of estrogen production, including pathways that can be targeted to inhibit aromatase specifically within the breast. This review aims to present some of the key findings in this regard.

Hypoxia and the extracellular matrix: drivers of tumour metastasis

Of the deaths attributed to cancer, 90% are due to metastasis, and treatments that prevent or cure metastasis remain elusive. Emerging data indicate that hypoxia and the extracellular matrix (ECM) might have crucial roles in metastasis. During tumour evolution, changes in the composition and the overall content of the ECM reflect both its biophysical and biological properties and these strongly influence tumour and stromal cell properties, such as proliferation and motility. Originally thought of as independent contributors to metastatic spread, recent studies have established a direct link between hypoxia and the composition and the organization of the ECM, which suggests a new model in which multiple microenvironmental signals might converge to synergistically influence metastatic outcome.

Mammographic density-a review on the current understanding of its association with breast cancer

There has been considerable recent interest in the genetic, biological and epidemiological basis of mammographic density (MD), and the search for causative links between MD and breast cancer (BC) risk. This report will critically review the current literature on MD and summarize the current evidence for its association with BC. Keywords 'mammographic dens*', 'dense mammary tissue' or 'percent dens*' were used to search the existing literature in English on PubMed and Medline. All reports were critically analyzed. The data were assigned to one of the following aspects of MD: general association with BC, its relationship with the breast hormonal milieu, the cellular basis of MD, the generic variations of MD, and its significance in the clinical setting. MD adjusted for age, and BMI is associated with increased risk of BC diagnosis, advanced tumour stage at diagnosis and increased risk of both local recurrence and second primary cancers. The MD measures that predict BC risk have high heritability, and to date several genetic markers associated with BC risk have been found to also be associated with these MD risk predictors. Change in MD could be a predictor of the extent of chemoprevention with tamoxifen. Although the biological and genetic pathways that determine and perhaps modulate MD remain largely unresolved, significant inroads are being made into the understanding of MD, which may lead to benefits in clinical screening, assessment and treatment strategies. This review provides a timely update on the current understanding of MD's association with BC risk.

Relations of omega-3 and omega-6 intake with mammographic breast density

PURPOSE

Omega-3 (n-3) and n-6 fatty acids (FA) intake could influence the occurrence of certain diseases such as breast cancer but little is known about their relation to mammographic density (MD). The purpose of this study is to examine the association of the intake of n-3 FA and n-6 FA with MD among 777 premenopausal and 783 postmenopausal women.

METHODS

In this cross-sectional study, FA intake was assessed with a self-administered food-frequency questionnaire and MD was measured using a computer-assisted method. Multivariate analyses were performed by using generalized linear models to evaluate the associations of quartiles of FA intake with MD.

RESULTS

For increasing quartiles of total long-chain n-3 FA intake (< 0.11, 0.11-0.20, 0.21-0.32, and ≥ 0.33 g/day), adjusted mean MD was 29, 29, 27, and 25 %, respectively (P trend = 0.005). This association remained significant among postmenopausal (P trend = 0.006) but not among premenopausal (P trend = 0.21) women. No significant association was found between n-6 FA intake and MD. However, for increasing quartiles of the n-6 FA/long-chain n-3 FA ratio intake (< 31.75, 31.75-52.28, 52.29-94.28, and ≥ 94.29), adjusted mean MD was 26, 27, 29, and 29 %, respectively (P trend = 0.008).

CONCLUSIONS

Higher intake of long-chain n-3 FA was associated with lower MD, suggesting that increased long-chain n-3 FA intake could be a strategy for breast cancer prevention.

Epithelial-mesenchymal transition: general principles and pathological relevance with special emphasis on the role of matrix metalloproteinases

Epithelial-mesenchymal transition (EMT) is a physiological process in which epithelial cells acquire the motile and invasive characteristics of mesenchymal cells. Although EMT in embryonic development is a coordinated, organized process involving interaction between many different cells and tissue types, aspects of the EMT program can be inappropriately activated in response to microenvironmental alterations and aberrant stimuli, and this can contribute to disease conditions including tissue fibrosis and cancer progression. Here we will outline how EMT functions in normal development, how it could be activated in pathologic conditions-especially by matrix metalloproteinases-and how it may be targeted for therapeutic benefit.

Body size across the life course, mammographic density, and risk of breast cancer

Adult body mass index (BMI) is inversely associated with premenopausal breast cancer risk, and childhood and adolescent body size is inversely associated with breast cancer risk in pre- and postmenopausal women. Breast density is inversely related to body size and may play a role in the association of body size with breast cancer risk. The authors conducted a nested case-control study including 1,528 cases and 2,844 controls from the Nurses' Health Study (1989-2004) and Nurses' Health Study II (1996-2003). Prior to breast cancer diagnosis, participants reported their body fatness during childhood and adolescence, BMI at age 18 years, and current BMI. Mammographic density was measured by using a computer-assisted thresholding method. The inverse association between adult BMI and premenopausal breast cancer (for BMI ≥30 vs. BMI 20-22.4, odds ratio = 0.64, 95% confidence interval: 0.38, 1.06) (P(trend) = 0.36) became positive after adjustment for mammographic density (odds ratio = 1.28, 95% confidence interval: 0.72, 2.30) (P(trend) = 0.07). Conversely, the inverse association between childhood and adolescent body size and breast cancer risk remained after adjustment for mammographic density. The inverse association between adult BMI and premenopausal breast cancer risk may be partially due to negative confounding by mammographic density. Conversely, mammographic density does not appear to explain the inverse association between childhood and adolescent body fatness and breast cancer risk.

Tissue composition of mammographically dense and non-dense breast tissue

Mammographic density is a strong risk factor for breast cancer but its underlying biology in healthy women is not well-defined. Using a novel collection of core biopsies from mammographically dense versus non-dense regions of the breasts of healthy women, we examined histologic and molecular differences between these two tissue types. Eligible participants were 40 + years, had a screening mammogram and no prior breast cancer or current endocrine therapy. Mammograms were used to identify dense and non-dense regions and ultrasound-guided core biopsies were performed to obtain tissue from these regions. Quantitative assessment of epithelium, stroma, and fat was performed on dense and non-dense cores. Molecular markers including Ki-67, estrogen receptor (ER) and progesterone receptor (PR) were also assessed for participants who had >0% epithelial area in both dense and non-dense tissue. Signed rank test was used to assess within woman differences in epithelium, stroma and fat between dense and non-dense tissue. Differences in molecular markers (Ki-67, ER, and PR) were analyzed using generalized linear models, adjusting for total epithelial area. Fifty-nine women, mean age 51 years (range: 40-82), were eligible for analyses. Dense tissue was comprised of greater mean areas of epithelium and stroma (1.1 and 9.2 mm(2) more, respectively) but less fat (6.0 mm(2) less) than non-dense tissue. There were no statistically significant differences in relative expression of Ki-67 (P = 0.82), ER (P = 0.09), or PR (P = 0.96) between dense and non-dense tissue. Consistent with prior reports, we found that mammographically dense areas of the breast differ histologically from non-dense areas, reflected in greater proportions of epithelium and stroma and lesser proportions of fat in the dense compared to non-dense breast tissue. Studies of both epithelial and stromal components are important in understanding the association between mammographic density and breast cancer risk.

Assessment of mammographic density before and after first full-term pregnancy

Mammographic density (MD) has consistently been found as one of the strongest breast cancer risk factors. In our study, both qualitative and quantitative density measurements were performed in a hospital-based group of premenopausal women before and after first full-term pregnancy providing an opportunity for direct evaluation of the effects of one pregnancy on MD. Mammograms were obtained from 23 women before and after first full-term pregnancy and from 28 nulliparous controls. MD was determined by a standard qualitative assessment method using the Breast Imaging Reporting and Data System, and a quantitative computer-based threshold method (0-100%). The mean age at mammography before and after pregnancy was 31 and 34 years, respectively, with a mean difference of 40 months between mammographies. The quantitative density assessment showed a significant reduction in relative MD after pregnancy of 12 percentage points (8.6-15.4), compared with 3.1 (0.0-6.2) in the nulliparous control group (P<0.001). A reduction in MD of more than 10% was seen in 52% of the patients, compared with 18% of the controls. The qualitative density assessment confirmed a reduction in MD after pregnancy by one Breast Imaging Reporting and Data System category (P=0.02). This longitudinal study showed that MD can be influenced by one full-term pregnancy. This effect was seen with both quantitative and qualitative assessment methods. It may be hypothesized that breast cancer risk reduction associated with pregnancy is mediated through a direct reduction of MD, and MD assessment might be incorporated in individualizing risk assessment and prevention.

Polymorphisms in genes involved in the estrogen pathway and mammographic density

Background

Single nucleotide polymorphisms (SNPs) in genes involved in the estrogen pathway appear to be associated with breast cancer risk and possibly with mammographic density (MD), but little is known of these associations among premenopausal women. This study examines the association of 11 polymorphisms in five estrogen-related genes (estrogen receptors alpha and beta (ERα, ERβ), 17β-hydroxysteroid dehydrogenase 1 (HSD17B1), catechol-O-methyltransferase (COMT), cytochrome P450 1B1 (CYP1B1)) with premenopausal MD. Effect modification of four estrogen-related factors (parity, age at menarche, hormonal derivatives use and body mass index (BMI)) on this relation is also assessed.

Methods

Polymorphisms were genotyped in 741 premenopausal Caucasian women whose MD was measured in absolute density (AD, cm²) and percent density using a computer-assisted method. Multivariate linear models were used to examine the associations (P_trend) and interactions (P_i).

Results

None of the SNPs showed a statistically significant association with AD. However, each additional rare allele of rs1056836 CYP1B1 was associated with a reduction in AD among nulliparous women (P_trend = 0.004), while no association was observed among parous women (P_trend = 0.62; P_i = 0.02). An increase in the number of rare alleles of the HSD17B1 SNP (rs598126 and rs2010750) was associated with an increase in AD among women who never used hormonal derivatives (P_trend = 0.06 and P_trend = 0.04, respectively), but with a decrease in AD among past hormonal derivatives users (P_trend = 0.04; P_i = 0.02 and P_trend = 0.08; P_i = 0.01, respectively). Moreover, a negative association of rs598126 HSD17B1 SNP with AD was observed among women with higher BMI (>median) (P_trend = 0.01; P_i = 0.02). A negative association between an increased number of rare alleles of COMT rs4680 SNP and AD was limited to women who never used hormonal derivatives (P_trend = 0.02; P_i = 0.03) or with late age at menarche (>median) (P_trend = 0.03; P_i = 0.02). No significant association was observed between polymorphisms in the ERα or ERβ genes and AD. Similar results, although less significant, were observed when MD was assessed in percent density.

Conclusion

SNPs located in CYP1B1, COMT or HSD17B1 genes seem to be associated with MD in some strata of estrogen-related factors. Our findings suggest that modifying effects of estrogen-related factors should be considered when evaluating associations of polymorphisms in estrogen-related genes with premenopausal mammographic density.

Mammographic density, plasma vitamin D levels and risk of breast cancer in postmenopausal women

Mammographic density is a strong risk factor for breast cancer, but the underlying biology for this association is unknown. Studies suggest that vitamin D may reduce breast cancer risk and dietary vitamin D intake has been associated with reduced breast density. We conducted a case-control study nested within the Nurses' Health Study cohort consisting of 463 and 497 postmenopausal cases and controls, respectively. We examined the association between mammographic density and plasma levels of 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)(2)D]. We assessed whether plasma vitamin D metabolites modify the association between breast density and breast cancer. Percent mammographic density was measured from digitized film mammograms. Generalized linear models were used to determine mean percent breast density per quartile of vitamin D metabolite. Logistic regression models were used to calculate relative risks and confidence intervals. All models were adjusted for matching variables and potential confounders. We found no cross-sectional association between circulating levels of 25(OH)D or 1,25(OH)(2)D with mammographic density. Women in the highest tertile of mammographic density and lowest tertile of plasma 25(OH)D had 4 times greater risk of breast cancer than women with the lowest mammographic density and highest plasma 25(OH)D levels (RR = 3.8; 95% CI: 2.0-7.3). The overall interaction between mammographic density and plasma 25(OH)D was nonsignificant (p-het = 0.20). These results indicate that the association between mammographic density and breast cancer is independent of plasma vitamin D metabolites in postmenopausal women. Further research examining vitamin D, mammographic density and breast cancer risk is warranted.

Matrix metalloproteinase-induced epithelial-mesenchymal transition in breast cancer

Matrix metalloproteinases (MMPs) degrade and modify the extracellular matrix (ECM) as well as cell-ECM and cell-cell contacts, facilitating detachment of epithelial cells from the surrounding tissue. MMPs play key functions in embryonic development and mammary gland branching morphogenesis, but they are also upregulated in breast cancer, where they stimulate tumorigenesis, cancer cell invasion and metastasis. MMPs have been investigated as potential targets for cancer therapy, but clinical trials using broad-spectrum MMP inhibitors yielded disappointing results, due in part to lack of specificity toward individual MMPs and specific stages of tumor development. Epithelial-mesenchymal transition (EMT) is a developmental process in which epithelial cells take on the characteristics of invasive mesenchymal cells, and activation of EMT has been implicated in tumor progression. Recent findings have implicated MMPs as promoters and mediators of developmental and pathogenic EMT processes in the breast. In this review, we will summarize recent studies showing how MMPs activate EMT in mammary gland development and in breast cancer, and how MMPs mediate breast cancer cell motility, invasion, and EMT-driven breast cancer progression. We also suggest approaches to inhibit these MMP-mediated malignant processes for therapeutic benefit.

Can mammographic assessments lead to consider density as a risk factor for breast cancer?

Admitting that mammographic breast density is an important independent risk factor for breast cancer in the general population, has a crucial economical health care impact, since it might lead to increasing screening frequency or reinforcing additional modalities. Thus, the impact of density as a risk factor has to be carefully investigated and might be debated. Some authors suggested that high density would be either a weak factor or confused with a masking effect. Others concluded that most of the studies have methodological biases in basic physics to quantify percentage of breast density, as well as in mammographic acquisition parameters. The purpose of this review is to evaluate mammographic procedures and density assessments in published studies regarding density as a breast cancer risk. No standardization was found in breast density assessments and compared density categories. High density definitions varied widely from 25 to 75% of dense tissues on mammograms. Some studies showed an insufficient follow-up to reveal masking effect related to mammographic false negatives. Evaluating breast density impact needs thorough studies with consensual mammographic procedures, methods of density measurement, breast density classification as well as a standardized definition of high breast density. Digital mammography, more effective in dense breasts, should help to re-evaluate the issue of density as a risk factor for breast cancer.

A prospective study of variability in mammographic density during the menstrual cycle

Mammographic breast density has been proposed as a surrogate endpoint in breast cancer prevention studies, but little is known about its variability over time, particularly in relation to menstrual cycle phase. The purpose of this study was to assess variation in breast density on digital mammograms using quantitative and qualitative density measures. Menstrual cycle phase was determined by salivary estradiol and progesterone assays. 73 healthy subjects with regular menses had 1-3 mammograms with paired saliva collection during a 12-month period. The mean difference in density as a percentage of the mean density was calculated for follicular-luteal (n = 50), luteal-luteal (n = 26) and follicular-follicular (n = 23) pairs in the same woman using the same breast. Two density measures (measurement of dense area and BIRADS) were used. The mean luteal density exceeded the mean follicular density by 7.1-9.2%, but density differences between luteal pairs and follicular pairs did not exceed 5%. The intraclass correlation for measurement of dense area was greater than 85% in all phases of the menstrual cycle, but was below 50% for BIRADS for luteal-follicular and follicular-follicular pairs. Our study provides estimates of the amount of variation in mammographic density during the menstrual cycle, and that inherent in repeated density measurement in premenopausal women, and suggests that menstrual phase of mammographic evaluation should be controlled for in intervention studies where density is being used as a surrogate measure.

Expression of syndecan-1 in histologically normal breast tissue from postmenopausal women with breast cancer according to mammographic density

OBJECTIVE

To analyze the expression of Syndecan-1 in dense and non-dense human breast tissue.

METHODS

Specimens of histologically normal tissue were obtained from postmenopausal women undergoing surgery for breast cancer. Each tissue block was subject to radiological examination and pair-wise samples of dense and non-dense tissue were collected. Semi-quantitative assessment of immunohistochemical staining intensity for Syndecan-1 and estrogen receptor subtypes was performed.

RESULTS

The expression of Syndecan-1 in all tissue compartments was significantly higher in dense than in non-dense specimens. The strongest staining was recorded in stromal tissue. There was a strong correlation between epithelial estrogen receptor alpha and stromal cell Syndecan-1 expression in dense tissue (rs = 0.7; p = 0.02). This association was absent in non-dense tissue.

CONCLUSION

An increase of Syndecan-1 in all tissue compartments and a redistribution from epithelium to stroma may be a characteristic feature for dense breast tissue.

Mammographic density and epithelial histopathologic markers

BACKGROUND

We explored the association of mammographic density, a breast cancer risk factor, with hormonal and proliferation markers in benign tissue from tumor blocks of pre-and postmenopausal breast cancer cases.

METHODS

Breast cancer cases were recruited from a case-control study on breast density. Mammographic density was assessed on digitized prediagnostic mammograms using a computer-assisted method. For 279 participants of the original study, we obtained tumor blocks and prepared tissue microarrays (TMA), but benign tissue cores were only available for 159 women. The TMAs were immunostained for estrogen receptor alpha (ERalpha) and beta (ERbeta), progesterone receptor (PR), HER2/neu, Ki-67, and Proliferating Cell Nuclear Antigen (PCNA). We applied general linear models to compute breast density according to marker expression.

RESULTS

A substantial proportion of the samples were in the low or no staining categories. None of the results was statistically significant, but women with PR and ERbeta staining had 3.4% and 2.4% higher percent density. The respective values for Caucasians were 5.7% and 11.6% but less in Japanese women (3.5% and -1.1%). Percent density was 3.4% higher in women with any Ki-67 staining and 2.2% in those with positive PCNA staining.

CONCLUSION

This study detected little evidence for an association between mammographic density and expression of steroid receptors and proliferation markers in breast tissue, but it illustrated the problems of locating tumor blocks and benign breast tissue samples for epidemiologic research. Given the suggestive findings, future studies examining estrogen effects in tissue, cell proliferation, and density in the breast may be informative.

Lifestyle, genes, and cancer

It is estimated that almost 1.5 million people in the USA are diagnosed with cancer every year. However, due to the substantial effect of modifiable lifestyle factors on the most prevalent cancers, it has been estimated that 50% of cancer is preventable. Physical activity, weight loss, and a reduction in alcohol use can strongly be recommended for the reduction of breast cancer risk. Similarly, weight loss, physical activity, and cessation of tobacco use are important behavior changes to reduce colorectal cancer risk, along with the potential benefit for the reduction of red meat consumption and the increase in folic acid intake. Smoking cessation is still the most important prevention intervention for reducing lung cancer risk, but recent evidence indicates that increasing physical activity may also be an important prevention intervention for this disease. The potential benefit of lifestyle change to reduce prostate cancer risk is growing, with recent evidence indicating the importance of a diet rich in tomato-based foods and weight loss. Also, in the cancers for which there are established lifestyle risk factors, such as physical inactivity for breast cancer and obesity for colorectal cancer, there is emerging information on the role that genetics plays in interacting with these factors, as well as the interaction of combinations of lifestyle factors. Integration of genetic information into lifestyle factors can help to clarify the causal relationships between lifestyle and genetic factors and assist in better identifying cancer risk, ultimately leading to better-informed choices about effective methods to enhance health and prevent cancer.

Breast density assessment in adolescent girls using dual-energy X-ray absorptiometry: a feasibility study

Breast density, the radiographically opaque fraction of the breast in a mammogram, is one of the strongest biomarkers of breast cancer risk. However, younger populations do not typically have mammograms due to radiation concerns. This study explored a commercially available dual-energy X-ray absorptiometer (DXA) system as a low-dose method to measure breast fibroglandular density in adolescent girls. Eighteen girls (13-14 years old) indicated their breast development according to Tanner and underwent three dedicated DXA scans, two of their left and one of their right breasts. Total projected breast area was manually delineated on each image and percent fibroglandular volume density (%FGV), absolute fibroglandular volume (FGV), total breast area, and volume were computed. It was possible to image breasts representing all five Tanner stages; %FGV ranged from 31.9% to 92.2% with a mean of 71.1 +/- 14.8%, whereas FGV ranged from 80 to 270 cm(3) with a mean of 168 +/- 54 cm(3). Left and right breast %FGV were highly correlated (r(p) = 0.97, P < 0.0001) and of the same magnitude (P = 0.18). However, left total volume and FGV were larger than the right by 38 cm(3) (P = 0.04) and 19 cm(3) (P = 0.02), respectively. Total volume and FGV increased by Tanner stage, whereas %FGV did not. Our method had excellent precision for %FGV and moderate precision for FGV (root mean square SDs of 2.4% and 16.6 cm(3)). These pilot data indicate that dedicated DXA breast scans may be useful in studies exploring breast density in girls.

Columnar cell lesions, mammographic density and breast cancer risk

BACKGROUND

Mammographic density is the third largest risk factor for ductal carcinoma in-situ (DCIS) and invasive breast cancer. However, the question of whether risk-mediating precursor histological changes, such as columnar cell lesions (CCLs), can be found in dense but non-malignant breast tissues has not been systematically addressed. We hypothesized that CCLs may be related to breast composition, in particular breast density, in non-tumour containing breast tissue.

PATIENTS AND METHODS

We examined randomly selected tissue samples obtained by bilateral subcutaneous mastectomy from a forensic autopsy series, where tissue composition was assessed, and in which there had been no selection of subjects or histological specimens for breast disease. We reviewed H&E slides for the presence of atypical and non-atypical CCLs and correlated with histological features measured using quantitative microscopy.

RESULTS

CCLs were seen in 40 out of 236 cases (17%). The presence of CCLs was found to be associated with several measures of breast tissue composition, including radiographic density: high Faxitron Wolfe Density (P = 0.037), high density estimated by percentage non-adipose tissue area (P = 0.037), high percentage collagen (P = 9.2E-05) and high percentage glandular area (P = 2E-05). DCIS was identified in two atypical CCL cases. The extent of CCL was not associated with any of the examined variables.

CONCLUSION

Our study is the first to report a possible association between CCLs and breast tissue composition, including mammographic density. Our data suggest that prospective elucidation of the strength and nature of the clinicopathological correlation may lead to an enhanced understanding of mammographic density and evidence based management strategies.

Mammographic density, breast cancer risk and risk prediction

In this review, we examine the evidence for mammographic density as an independent risk factor for breast cancer, describe the risk prediction models that have incorporated density, and discuss the current and future implications of using mammographic density in clinical practice. Mammographic density is a consistent and strong risk factor for breast cancer in several populations and across age at mammogram. Recently, this risk factor has been added to existing breast cancer risk prediction models, increasing the discriminatory accuracy with its inclusion, albeit slightly. With validation, these models may replace the existing Gail model for clinical risk assessment. However, absolute risk estimates resulting from these improved models are still limited in their ability to characterize an individual's probability of developing cancer. Promising new measures of mammographic density, including volumetric density, which can be standardized using full-field digital mammography, will likely result in a stronger risk factor and improve accuracy of risk prediction models.

The role of various modalities in breast imaging

BACKGROUND

Breast cancer is the most common type of cancer in women worldwide. Mammography is considered the "gold standard" in the evaluation of the breast from an imaging perspective. Apart from mammography, ultrasound examination and magnetic resonance imaging are being offered as adjuncts to the preoperative workup. Recently, other new modalities like positron emission tomography, 99mTc-sestamibi scintimammography, and electrical impedance tomography (EIT) are also being offered. However, there is still controversy over the most appropriate use of these new modalities. Based on the literature, this review evaluates the role of various modalities used in the screening and diagnosis of breast cancer.

METHODS AND RESULTS

Based on relevant literatures this article gives an overview of the old and new modalities used in the field of breast imaging. A narrative literature review of all the relevant papers known to the authors was conducted. The search of literatures was done using pubmed and ovid search engines. Additional references were found through bibliography reviews of relevant articles. It was clear that though various new technics and methods have emerged, none have substituted mammography and it is still the only proven screening method for the breast as of date.

CONCLUSION

From the literature it is clear that apropos modern radiology's impact on diagnosis, staging and patient follow-up, only one imaging technique has had a significant impact on screening asymptomatic individuals for cancer i.e.; low-dose mammography. Mammography is the only screening test proven in breast imaging. Positron emission tomography (PET) also plays an important role in staging breast cancer and monitoring treatment response. As imaging techniques improve, the role of imaging will continue to evolve with the goal remaining a decrease in breast cancer morbidity and mortality. Progress in the development and commercialisation of EIT breast imaging system will definitely help to promote other systems and applications based on the EIT and similar visualization methods. Breast ultrasound and breast magnetic resonance imaging (MRI) are frequently used adjuncts to mammography in today's clinical practice and these techniques enhance the radiologist's ability to detect cancer and assess disease extent, which is crucial in treatment planning and staging.

Mammographic density does not correlate with Ki-67 expression or cytomorphology in benign breast cells obtained by random periareolar fine needle aspiration from women at high risk for breast cancer

Background

Ki-67 expression is a possible risk biomarker and is currently being used as a response biomarker in chemoprevention trials. Mammographic breast density is a risk biomarker and is also being used as a response biomarker. We previously showed that Ki-67 expression is higher in specimens of benign breast cells exhibiting cytologic atypia that are obtained by random periareolar fine needle aspiration (RPFNA). It is not known whether there is a correlation between mammographic density and Ki-67 expression in benign breast ductal cells obtained by RPFNA.

Methods

Included in the study were 344 women at high risk for developing breast cancer (based on personal or family history), seen at The University of Kansas Medical Center high-risk breast clinic, who underwent RPFNA with cytomorphology and Ki-67 assessment plus a mammogram. Mammographic breast density was assessed using the Cumulus program. Categorical variables were analyzed by χ² test, and continuous variables were analyzed by nonparametric test and linear regression.

Results

Forty-seven per cent of women were premenopausal and 53% were postmenopausal. The median age was 48 years, median 5-year Gail Risk was 2.2%, and median Ki-67 was 1.9%. The median mammographic breast density was 37%. Ki-67 expression increased with cytologic abnormality (atypia versus no atypia; P ≤ 0.001) and younger age (≤50 years versus >50 years; P ≤ 0.001). Mammographic density was higher in premenopausal women (P ≤ 0.001), those with lower body mass index (P < 0.001), and those with lower 5-year Gail risk (P = 0.001). Mammographic density exhibited no correlation with Ki-67 expression or cytomorphology.

Conclusion

Given the lack of correlation of mammographic breast density with either cytomorphology or Ki-67 expression in RPFNA specimens, mammographic density and Ki-67 expression should be considered as potentially complementary response biomarkers in breast cancer chemoprevention trials.

Fibrosis and cancer: do myofibroblasts come also from epithelial cells via EMT?

Myofibroblasts produce and modify the extracellular matrix (ECM), secrete angiogenic and pro-inflammatory factors, and stimulate epithelial cell proliferation and invasion. Myofibroblasts are normally induced transiently during wound healing, but inappropriate induction of myofibroblasts causes organ fibrosis, which greatly enhances the risk of subsequent cancer development. As myofibroblasts are also found in the reactive tumor stroma, the processes involved in their development and activation are an area of active investigation. Emerging evidence suggests that a major source of fibrosis- and tumor-associated myofibroblasts is through transdifferentiation from non-malignant epithelial or epithelial-derived carcinoma cells through epithelial-mesenchymal transition (EMT). This review will focus on the role of EMT in fibrosis, considered in the context of recent studies showing that exposure of epithelial cells to matrix metalloproteinases (MMPs) can lead to increased levels of cellular reactive oxygen species (ROS) that stimulate transdifferentiation to myofibroblast-like cells. As deregulated MMP expression and increased cellular ROS are characteristic of both fibrosis and malignancy, these studies suggest that increased MMP expression may stimulate fibrosis, tumorigenesis, and tumor progression by inducing a specialized EMT in which epithelial cells transdifferentiate into activated myofibroblasts. This connection provides a new perspective on the development of the fibrosis and tumor microenvironments.

Endogenous hormone levels, mammographic density, and subsequent risk of breast cancer in postmenopausal women

BACKGROUND

Mammographic density and circulating sex hormones are two well-confirmed predictors of breast cancer risk. Whether mammographic density reflects levels of endogenous sex hormones is unclear. We examined whether these predictors are independently associated with breast cancer risk in a prospective study.

METHODS

We conducted a nested case-control study within the Nurses' Health Study cohort of 253 case subjects with breast cancer and 520 control subjects. All participants were postmenopausal women who were not using postmenopausal hormones at the time of both blood collection and mammography. Plasma levels of estradiol, free estradiol, testosterone, and free testosterone were evaluated. Mammographic density was assessed by use of computer-assisted analysis of mammograms. Logistic regression models that were adjusted for matching variables and potential confounders were used to calculate relative risks (RRs) and 95% confidence intervals (CIs). All statistical tests were two-sided.

RESULTS

Levels of circulating sex steroids and mammographic density were both statistically significantly and independently associated with breast cancer risk. The relative risk of breast cancer associated with mammographic density (RR for highest quartile compared with lowest quartile = 3.8, 95% CI = 2.2 to 6.6; P(trend)<.001) changed little when the analysis was adjusted for circulating estradiol (RR = 3.9, 95% CI = 2.2 to 6.9; P(trend)<.001) or circulating testosterone (RR = 4.1, 95% CI = 2.3 to 7.2; P(trend)<.001). Circulating levels of estradiol (RR = 2.4, 95% CI = 1.4 to 4.0) and of testosterone (RR = 2.0, 95% CI = 1.2 to 3.1) were both associated with breast cancer risk, before and after adjustment for mammographic density. In a joint analysis of mammographic density and plasma testosterone, the risk of breast cancer was highest in the highest tertiles of both relative to the lowest tertiles of both (RR = 6.0, 95% CI = 2.6 to 14.0). A similar pattern was observed in the joint analysis of estradiol and mammographic density (RR = 4.1, 95% CI = 1.7 to 9.8).

CONCLUSIONS

Circulating sex steroid levels and mammographic density appear strongly and independently associated with the risk of breast cancer in postmenopausal women.

Mammographic breast density as a general marker of breast cancer risk

Mammographic breast density is a strong risk factor for breast cancer but whether breast density is a general marker of susceptibility or is specific to the location of the eventual cancer is unknown. A study of 372 incident breast cancer cases and 713 matched controls was conducted within the Mayo Clinic mammography screening practice. Mammograms on average 7 years before breast cancer were digitized, and quantitative measures of percentage density and dense area from each side and view were estimated. A regional density estimate accounting for overall percentage density was calculated from both mammogram views. Location of breast cancer and potential confounders were abstracted from medical records. Conditional logistic regression was used to estimate associations, and C-statistics were used to evaluate the strength of risk prediction. There were increasing trends in breast cancer risk with increasing quartiles of percentage density and dense area, irrespective of the side of the breast with cancer (P(trends) < 0.001). Percentage density from the ipsilateral side [craniocaudal (CC): odds ratios (ORs), 1.0 (ref), 1.7, 3.1, and 3.1; mediolateral oblique (MLO): ORs, 1.0 (ref), 1.5, 2.2, and 2.8] and the contralateral side [CC: ORs, 1.0 (ref), 1.8, 2.2, and 3.7; MLO: ORs, 1.0 (ref), 1.6, 1.9, and 2.5] similarly predicted case-control status (C-statistics, 0.64-65). Accounting for overall percentage density, density in the region where the cancer subsequently developed was not a significant risk factor [CC: 1.0 (ref), 1.3, 1.0, and 1.2; MLO: 1.0 (ref), 1.1, 1.0, and 1.1 for increasing quartiles]. Results did not change when examining mammograms 3 years on average before the cancer. Overall mammographic density seems to represent a general marker of breast cancer risk that is not specific to breast side or location of the eventual cancer.

Body size, mammographic density, and breast cancer risk

BACKGROUND

Greater weight and body mass index (BMI) are negatively correlated with mammographic density, a strong risk factor for breast cancer, and are associated with an increased risk of breast cancer in postmenopausal women, but with a reduced risk in premenopausal women. We have examined the associations of body size and mammographic density on breast cancer risk.

METHOD

We examined the associations of body size and the percentage of mammographic density at baseline with subsequent risk of breast cancer among 1,114 matched case-control pairs identified from three screening programs. The effect of each factor on risk of breast cancer was examined before and after adjustment for the other, using logistic regression.

RESULTS

In all subjects, before adjustment for mammographic density, breast cancer risk in the highest quintile of BMI, compared with the lowest, was 1.04 [95% confidence interval (CI), 0.8-1.4]. BMI was associated positively with breast cancer risk in postmenopausal women, and negatively in premenopausal women. After adjustment for density, the risk associated with BMI in all subjects increased to 1.60 (95% CI, 1.2-2.2), and was positive in both menopausal groups. Adjustment for BMI increased breast cancer risk in women with 75% or greater density, compared with 0%, increased from 4.25 (95% CI, 1.6-11.1) to 5.86 (95% CI, 2.2-15.6).

CONCLUSION

BMI and mammographic density are independent risk factors for breast cancer, and likely to operate through different pathways. The strong negative correlated between them will lead to underestimation of the effects on risk of either pathway if confounding is not controlled.

Longitudinal measurement of clinical mammographic breast density to improve estimation of breast cancer risk

BACKGROUND

Whether a change over time in clinically measured mammographic breast density influences breast cancer risk is unknown.

METHODS

From January 1993 to December 2003, data that included American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) breast density categories (1-4 in order of increasing density) were collected prospectively on 301,955 women aged 30 and older who were not using postmenopausal hormone replacement therapy and underwent at least two screening mammography examinations; 2639 of the women were diagnosed with breast cancer within 1 year of the last examination. Women's first and last BI-RADS breast density (average 3.2 years apart) and logistic regression were used to model the odds of having invasive breast cancer or ductal carcinoma in situ diagnosed within 12 months of the last examination by change in BI-RADS category. Rates of breast cancer adjusted for age, mammography registry, and time between screening examinations were estimated from this model. All statistical tests were two-sided.

RESULTS

The rate (breast cancers per 1000 women) of breast cancer was higher if BI-RADS breast density category increased from 1 to 2 (5.6, 95% confidence interval [CI] = 4.7 to 6.9) or 1 to 3 (9.9, 95% CI = 6.4 to 15.5) compared to when it remained at BI-RADS density of 1 (3.0, 95% CI = 2.3 to 3.9; P<.001 for trend). Similar and statistically significant trends between increased or decreased density and increased or decreased risk of breast cancer, respectively, were observed for women whose breast density category was initially 2 or 3 and changed categories. BI-RADS density of 4 on the first examination was associated with a high rate of breast cancer (range 9.1-13.4) that remained high even if breast density decreased.

CONCLUSION

An increase in BI-RADS breast density category within 3 years may be associated with an increase in breast cancer risk and a decrease in density category with a decrease in risk compared to breast cancer risk in women in whom breast density category remains unchanged. Two longitudinal measures of BI-RADS breast density may better predict a woman's risk of breast cancer than a single measure.

Benign breast biopsy diagnosis and subsequent risk of breast cancer

BACKGROUND

We examine benign breast biopsy diagnoses as reported by community pathologists in New Mexico and investigate associations with future breast cancer development.

METHODS

Using data collected between 1992 and 2000 by the New Mexico Mammography Project and cancer data through 2003 from the New Mexico Tumor Registry, we calculated breast cancer rates following 14,602 benign breast biopsies for women ages 30 to 89 years. For comparison, we also calculated the breast cancer rate following 215,283 normal screening mammograms. Hazard ratios (HR) are presented.

RESULTS

We identified 480 subsequent breast cancer diagnoses among 14,602 women with benign breast biopsies and 4,402 breast cancer diagnoses among 215,283 women with mammograms assigned a "negative" or "benign finding" assessment. Histologic diagnoses in absence of atypia had an age-adjusted HR of 1.95 [95% confidence interval (95% CI), 1.77-2.15]. Among low-risk histologic diagnoses, the strongest associations with subsequent breast cancer development included adenosis, apocrine metaplasia, calcifications, and ductal hyperplasia. Fibroadenoma, inflammation, and cysts did not exhibit an association with breast cancer development. Women with low-risk diagnoses and breast tissue characterized as fatty or with scattered densities had a HR of 2.09 (95% CI, 1.68-2.60), whereas women with low-risk histologic diagnoses and dense breasts had a HR of 3.36 (95% CI, 2.83-3.99).

CONCLUSIONS

The observed breast cancer occurrence contributes to evidence of increased risk following benign biopsy. The risk associated with histologic diagnoses in absence of atypia was twice the risk experienced by women with normal mammogram evaluations and may be modified by breast density.

Tibolone and breast cancer

Tibolone is a relatively new drug for postmenopausal women, which is structurally related to 19-nortestosterone derivatives and exhibits weak oestrogenic, progestogenic and androgenic activities. The effect of tibolone on breast tissue is still obscure. In vitro studies have shown conflicting results regarding the effects of tibolone on breast cells. On the other hand, although epidemiological studies show an increase in the risk of breast cancer among women treated with tibolone, accumulation of data obtained from radiological studies presents promising results. However, the safety of tibolone with regard to breast tissue needs to be investigated further, especially through well-designed, large-scale, randomised-controlled trials.

Varying levels of family history of breast cancer in relation to mammographic breast density (United States)

OBJECTIVE

We examined the relationship between breast cancer family history and mammographic breast density.

METHODS

Participants included 35,019 postmenopausal women aged >or=40 years enrolled in a population-based mammography screening program. We collected data on the number and type of 1st and 2nd degree female relatives with a history of breast cancer and their ages at diagnosis. We used the Breast Imaging Reporting and Data System breast density categories to identify women with fatty (1 = almost entirely fatty or 2 = scattered fibroglandular tissue) and dense (3 = heterogeneously dense or 4 = extremely dense) breasts. We used logistic regression to calculate odds ratios (OR) and 95% confidence intervals for dense (N = 18,111) compared to fatty breasts (N = 16,908).

RESULTS

The odds of having dense breasts were 17% greater for women with affected 1st degree relatives than women with no family history. The odds increased with more affected 1st degree relatives [>or=3 vs. none (OR = 1.46; 1.05-2.01)] and among women with >or=1 affected 1st degree relative diagnosed <50 years (OR = 1.22; 1.10-1.34).

CONCLUSIONS

Having a family history of breast cancer was more strongly associated with mammographic breast density when the affected relatives were more genetically similar. There may be common, yet undiscovered, genetic elements that affect breast cancer and mammographic breast density.

Clinical comparison of a novel breast DXA technique to mammographic density

We compare mammography breast density (BD(MD)) to the measure of breast composition using a clinical dual energy absorptiometry (DXA) system (BD(DXA)) calibrated to measure breast density. A DXA scanning protocol was developed to scan breasts isolated in the DXA scan field in either a prone pendulous or decubitus mediolateral position. A total of 17 participants were recruited among women undergoing clinical mammography examinations. Each participant had duplicate DXA scans and duplicate craniocaudal-view mammograms of their right breast with repositioning between each scan and one DXA and one craniocaudal-view mammogram of their left breast. The in vivo repeatability (RMS SD) of BD(DXA) and BD(MD) on duplicate scans was found to be 1.2% for BD(DXA) and 1.4% for BD(MD) when repeat BD(MD) measures were made on the same day. When repeat BD(MD) measures of the same breast were made more than 50 days apart, the repeatability decreased to 5.5%. Left and right breast measurements were highly correlated with both techniques at r2 = 0.98 for BD(DXA) and r2 = 0.86 for BD(MD). Moderate correlation (r2 = 0.52) was found between BD(DXA) and BD(MD) measurements. However, after recalibrating the DXA system to mammography reference materials, negative percent fibroglandular values were measured for the most fatty breasts. Thus, our results are reproducible and accurate to common mammography tissue standards, but did not accurately reflect true percent fibroglandular levels and further development of phantom standards are necessary. We conclude that breast composition can be precisely evaluated and assessed with clinical DXA densitometers at a lower dose than with mammographic breast density methods.

Dietary and lifestyle determinants of mammographic breast density. A longitudinal study in a Mediterranean population

High mammographic breast density (H-MBD) has been associated with increased breast cancer (BC) risk, even after adjustment for established BC risk factors. Only a few studies have examined the influence of diet on MBD. In a longitudinal study in Florence, Italy, we identified about 2,000 women with a mammogram taken 5 years after enrollment, when detailed information on dietary and lifestyle habits and anthropometric measurements had been collected. Original mammograms have been identified and retrieved (1,668; 83%), and MBD was assessed by 2 experienced readers, according to Wolfe's classification and a semiquantitative scale. By logistic analysis, we compared women with H-MBD (P2 + DY according to Wolfe's classification) with those with low-MBD (N1 + P1). H-MBD was confirmed to be inversely associated with BMI, number of children and breast feeding, while it was directly associated with higher educational level, premenopausal status and a previous breast biopsy. In multivariate analyses adjusted for non-dietary variables, H-MBD was inversely associated with increasing consumption of vegetables (p for trend = 0.005) and olive oil (p for trend = 0.04). An inverse association was also evident between H-MBD and frequent consumption of cheese and high intakes of beta-carotene, vitamin C, calcium and potassium (p for trend < or = 0.05). On the other hand, we found a positive association with increasing consumption of wine (p for trend = 0.01). This large longitudinal study, the first carried out in Mediterranean women, suggests that specific dietary components may play a key role in determining MBD in this population, thus possibly modulating BC risk.

Evaluation of mammographic density and 99mTc-sestamibi scintimammographic uptake in postmenopausal women on hormone replacement therapy

OBJECTIVE

To evaluate changes in mammographic density and (99m)Tc-sestamibi scintimammographic uptake in postmenopausal women on hormone replacement therapy (HRT).

METHODS

Seventy-five postmenopausal women were prospectively studied and allocated into three groups: 50 women were randomized to either Group 1 (G1, n=25), which received 2mg of 17beta-oestradiol continuously combined with 1mg of norethisterone acetate (E2/NETA, Kliogest, Medley) or Group 2 (G2), which received 2.5mg/day of tibolone (Livial, Organon). The remaining 25 women, who were asymptomatic and had no desire to undergo HRT, constituted the control group (G3). Each patient was submitted to both mammography and scintimammography at baseline and after six months. Mammographic density was evaluated by using the BI-RADS classification system. The classification system of Barros et al. was used in the interpretation of scintimammography. For statistical analysis, the Chi-square test, ANOVA and Pearson's correlation were used.

RESULTS

At six months, increased mammographic density was observed in 48% of G1, 12% of G2 and 16% of G3 patients (p<0.001). The increase in sestamibi uptake was 56% in G1, 28% in G2 and 24% in G3 (p<0.001). Increases in both density and uptake were significantly higher in the group on E2/NETA than among tibolone users and the controls.

CONCLUSION

In postmenopausal women, HRT with E2/NETA was associated with increased mammographic density and increased (99m)Tc-sestamibi scintimammographic uptakes, suggesting greater mithochondrial activity in the cells of the mammary duct. This was not observed in users of 2.5 mg of tibolone, demonstrating that the effects on the breast were reduced. The same was observed in the control group.

Nutritional predictors for cellular nipple aspirate fluid: Nutrition and Breast Health Study

The presence of epithelial cells in breast nipple aspirate fluid (NAF), irrespective of abnormality, has been associated with increased risk of breast cancer in previous studies. We sought to investigate whether the presence of epithelial cells in NAF is associated with nutritional parameters among 71 healthy premenopausal women who participated in the Nutrition and Breast Health Study and provided any samples of NAF during the study. Total of 142 samples which were obtained over a 1-year period of intervention with low-fat and/or high vegetable-fruit diets were available for cytological evaluation. The odds ratios (ORs) and 95% confidence intervals (CIs) for the detection of epithelial cells in NAF were estimated by fitting generalized estimating equations models by quartile level of nutritional parameters. The probability of yielding epithelial cell-positive NAF progressively increased with increasing total fat intake (p=0.001). The OR for the highest quartile level of fat intake, compared with lowest, was 7.22 (95% CI 1.14-45.82). On the other hand, there were a marginally significant inverse association with total fiber intake as well as an weak inverse association with the number of servings of fruit and vegetables. Furthermore, the probability of detecting epithelial cells in NAF decreased with increasing plasma levels of lutein and alpha-carotene (p-values for linear trend; 0.001 and 0.049, respectively). The ORs for the highest versus lowest quartile levels are 0.17 (95% CI 0.04-0.65) and 0.19 (95% CI 0.04-0.91), respectively. These results are generally in support of roles of nutritional factors in breast cancer and thus further studies are warranted.