Mammographic breast density, dense area, and breast area differences by phase in the menstrual cycle

Breast percent density changes in digital mammography pre- and post-radiotherapy

INTRODUCTION

Breast cancer (BC), the most frequently diagnosed malignancy among women worldwide, presents a public health challenge and affects mortality rates. Breast-conserving therapy (BCT) is a common treatment, but the risk from residual disease necessitates radiotherapy. Digital mammography monitors treatment response by identifying post-operative and radiotherapy tissue alterations, but accurate assessment of mammographic density remains a challenge. This study used OpenBreast to measure percent density (PD), offering insights into changes in mammographic density before and after BCT with radiation therapy.

METHODS

This retrospective analysis included 92 female patients with BC who underwent BCT, chemotherapy, and radiotherapy, excluding those who received hormonal therapy or bilateral BCT. Percent/percentage density measurements were extracted using OpenBreast, an automated software that applies computational techniques to density analyses. Data were analysed at baseline, 3 months, and 15 months post-treatment using standardised mean difference (SMD) with Cohen's d, chi-square, and paired sample t-tests. The predictive power of PD changes for BC was measured based on the receiver operating characteristic (ROC) curve analysis.

RESULTS

The mean age was 53.2 years. There were no significant differences in PD between the periods. Standardised mean difference analysis revealed no significant changes in the SMD for PD before treatment compared with 3- and 15-months post-treatment. Although PD increased numerically after radiotherapy, ROC analysis revealed optimal sensitivity at 15 months post-treatment for detecting changes in breast density.

CONCLUSIONS

This study utilised an automated breast density segmentation tool to assess the changes in mammographic density before and after BC treatment. No significant differences in the density were observed during the short-term follow-up period. However, the results suggest that quantitative density assessment could be valuable for long-term monitoring of treatment effects. The study underscores the necessity for larger and longitudinal studies to accurately measure and validate the effectiveness of quantitative methods in clinical BC management.

Diagnostic performance of screening mammography according to menstrual cycle among Asian women

PURPOSE

To investigate the performance metrics of screening mammography according to menstrual cycle week in premenopausal Asian women.

METHODS

This retrospective study included 69,556 premenopausal Asian women who underwent their first screening mammography between 2011 and 2019. The presence or absence of a breast cancer diagnosis within 12 months after the index screening mammography served as the reference standard, determined by linking the study data to the national cancer registry data. Menstrual cycles were calculated, and participants were assigned to groups according to weeks 1-4. The performance metrics included cancer detection rate (CDR), sensitivity, specificity, and positive predictive value (PPV), with comparisons across menstrual cycles.

RESULTS

Among menstrual cycles, the lowest CDR at 4.7 per 1000 women (95% confidence interval [CI], 3.8-5.8 per 1000 women) was observed in week 4 (all P < 0.05). The highest sensitivity of 72.7% (95% CI, 61.4-82.3) was observed in week 1, although the results failed to reach statistical significance. The highest specificity of 80.4% (95% CI, 79.5-81.3%) was observed in week 1 (P = 0.01). The lowest PPV of 2.2% (95% CI, 1.8-2.7) was observed in week 4 (all P < 0.05).

CONCLUSION

Screening mammography tended to show a higher performance during week 1 and a lower performance during week 4 of the menstrual cycle among Asian women. These results emphasize the importance of timing recommendations that consider menstrual cycles to optimize the effectiveness of screening mammography for breast cancer detection.

"Are changes in breast density during the menstrual cycle relevant? To what?"

PURPOSE

Cancers can be hidden by high breast density (BDen)- the masking effect (ME). BDen is also a modifiable and highly prevalent breast cancer risk (BCR) factor. The purposes of this study were to determine how much glandular volume (GVol), breast volume (BVol) and their ratio: BDen change during the menstrual cycle, and if these changes could affect ME or be relevant to results of interventional studies aiming to diminish BCR using these parameters as surrogates.

METHODS

We retrieved GVol, BVol and BDen data values obtained from 39,997 right mammograms performed with photon counting technique of 19,904 premenopausal women who reported their first day of last menses (FDLM). Many women had more than one study included over the years (with a different FDLM) but were not studied longitudinally. We segregated women by age (yearly), divided the menstrual cycle in 4 weeks, and assigned results with respect to the FDLM.

RESULTS

All parameters vary cyclically, with higher values in week 4 (GVol and BDen) or week 1 (BVol). Mean inter-week differences were very small for the three parameters, and diminished with age. However, especially in the youngest women, inter-week differences could be more than 10% for BDen, 15% for GVol, and 50% for BVol.

CONCLUSION

Small inter-week mean differences almost certainly rule out relevant changes to ME directly attributable to BDen. However, the possibility of large differences during the menstrual cycle in younger women, who are the ideal targets of interventional studies to diminish BCR, might distort results and should be accounted for.

Exploring Association of Breast Pain, Pregnancy, and Body Mass Index with Breast Tissue Elasticity in Healthy Women: Glandular and Fat Differences

Breast sonoelastography is a relatively novel ultrasound (US) method that enables estimation of tissue stiffness to estimate the elasticity of normal breast tissue and seek to correlate it with well-known breast cancer risk factors. Two hundred women of different age were included in the study and completed a questionnaire about personal, familiar, and reproductive history. Glandular and fatty tissue elasticity in all breast quadrants was measured by shear wave elastography (SWE). Mean elastographic values of breast tissue were calculated and compared to personal history risk factors. Elasticity of normal glandular tissue (66.4 kilopascals (kPa)) was higher than fatty tissue (26.1 kPa) in all breast quadrants and in both breasts. Lower outer quadrant (LOQ) had the lowest elasticity values of both parenchyma and fat. Higher elasticity values of breast tissue were confirmed in the left breast than in the right breast. Glandular and fat tissue elasticity negatively correlated with body mass index (BMI). Women with mastodynia had higher glandular elastographic values compared to subjects without breast pain. Nuliparity was also associated with higher elasticity of glandular breast tissue. The results of this study are promising and could, over time, contribute to a better understanding of glandular breast tissue elasticity as a potential risk factor for breast cancer.

Relationship Between Breast Ultrasound Background Echotexture and Magnetic Resonance Imaging Background Parenchymal Enhancement and the Effect of Hormonal Status Thereon

We studied the relationship between breast ultrasound background echotexture (BET) and magnetic resonance imaging (MRI) background parenchymal enhancement (BPE) and whether this relationship varied with hormonal status and amount of fibroglandular tissue (FGT) on MRI. Two hundred eighty-three Korean women (52.1 years; range = 27-79 years) with newly diagnosed primary breast cancer who underwent preoperative breast ultrasound and MRI were retrospectively studied. Background echotexture, BPE, and FGT were classified into 4 categories, and age, menopausal status, menstrual cycle regularity, and menstrual cycle stage at MRI were recorded. Background echotexture and BPE relationship was assessed overall, and in menopausal, FGT, menstrual cycle regularity, and menstrual cycle stage subgroups. Background echotexture and BPE correlated in women overall, and menopausal, FGT, and menstrual cycle subgroups and those in the first half of the cycle (all P < 0.001). Background echotexture reflects BPE, regardless of menopausal status, menstrual cycle regularity, and FGT and may be a biomarker of breast cancer risk.

Breast Density Assessment in Young Women with Ultrasound based on Speed of Sound: Influence of the Menstrual Cycle

To investigate changes in breast density (BD) during the menstrual cycle in young women in comparison to inter-breast and -segment changes as well as reproducibility of a novel Speed-of-Sound (SoS) Ultrasound (US) method.SoS-US uses a conventional US system with a reflector and a software add-on to quantify SoS in the retro-mammillary, inner and outer segments of both breasts. Twenty healthy women (18-40 years) with regular menstrual cycles were scanned twice with two weeks in-between. Three of these were additionally measured twice per week for 25 days. Average SoS (m/s) and ΔSoS (segment-variation SoS; m/s) were measured. Variations between follicular and luteal phases and changes over the four-week period were assessed. Inter-examiner and inter-reader agreements were also evaluated. Variances between cycle phases, examiners and readers were compared.No significant SoS difference was observed between follicular and luteal phases for the twenty women (P = .126), and between all different days for the three more frequently measured women (P = .892). Inter-reader (ICC = 0.999) and inter-examiner (ICC = 0.990) agreements were high. The SoS variance due to menstrual variations was not significantly larger than the inter-examiner uncertainty (P = .461). Inter-reader variations were significantly smaller than menstrual and examiner variations (P < .001).SoS-US showed high inter-examiner and inter-reader reproducibility. The alterations during the menstrual cycles were not significantly larger than the confidence interval of measurements.

Serum osteoprotegerin levels and mammographic density among high-risk women

PURPOSE

Mammographic density is a risk factor for breast cancer but the mechanism behind this association is unclear. The receptor activator of nuclear factor κB (RANK)/RANK ligand (RANKL) pathway has been implicated in the development of breast cancer. Given the role of RANK signaling in mammary epithelial cell proliferation, we hypothesized this pathway may also be associated with mammographic density. Osteoprotegerin (OPG), a decoy receptor for RANKL, is known to inhibit RANK signaling. Thus, it is of interest to evaluate whether OPG levels modify breast cancer risk through mammographic density.

METHODS

We quantified serum OPG levels in 57 premenopausal and 43 postmenopausal women using an enzyme-linked immunosorbent assay (ELISA). Cumulus was used to measure percent density, dense area, and non-dense area for each mammographic image. Subjects were classified into high versus low OPG levels based on the median serum OPG level in the entire cohort (115.1 pg/mL). Multivariate models were used to assess the relationship between serum OPG levels and the measures of mammographic density.

RESULTS

Serum OPG levels were not associated with mammographic density among premenopausal women (P ≥ 0.42). Among postmenopausal women, those with low serum OPG levels had higher mean percent mammographic density (20.9% vs. 13.7%; P = 0.04) and mean dense area (23.4 cm² vs. 15.2 cm²; P = 0.02) compared to those with high serum OPG levels after covariate adjustment.

CONCLUSIONS

These findings suggest that low OPG levels may be associated with high mammographic density, particularly in postmenopausal women. Targeting RANK signaling may represent a plausible, non-surgical prevention option for high-risk women with high mammographic density, especially those with low circulating OPG levels.

Association between expression of inflammatory markers in normal breast tissue and mammographic density among premenopausal and postmenopausal women

OBJECTIVE

Inflammatory markers may be associated with breast cancer risk. We assessed the association between expression levels of proinflammatory (interleukin 6, tumor necrosis factor-α, C-reactive protein, cyclooxygenase 2, leptin, serum amyloid A1, interleukin 8, and signal transducer and activator of transcription 3) and anti-inflammatory markers (transforming growth factor-β, interleukin 10, and lactoferrin) in normal breast tissue with mammographic density, a strong breast cancer risk indicator, among 163 breast cancer patients.

METHODS

The expression of inflammatory markers was visually evaluated on immunohistochemistry stained slides. The percent mammographic density (PMD) was estimated by a computer-assisted method in the contralateral cancer-free breast. We used generalized linear models to estimate means of PMD by median expression levels of the inflammatory markers while adjusting for age and waist circumference.

RESULTS

Higher expression levels (above median) of the proinflammatory marker interleukin 6 were associated with higher PMD among all women (24.1% vs 18.5%, P = 0.007). Similarly, higher expression levels (above median) of the proinflammatory markers (interleukin 6, tumor necrosis factor-α, C-reactive protein, and interleukin 8) were associated with higher PMD among premenopausal women (absolute difference in the PMD of 8.8% [P = 0.006], 7.7% [P = 0.022], 6.7% [P = 0.037], and 16.5% [P = 0.032], respectively). Higher expression levels (above median) of the anti-inflammatory marker transforming growth factor-β were associated with lower PMD among all (18.8% vs 24.3%, P = 0.005) and postmenopausal women (14.5% vs 20.7%, P = 0.013).

CONCLUSIONS

Our results provide support for the hypothesized role of inflammatory markers in breast carcinogenesis through their effects on mammographic density. Inflammatory markers could be targeted in future breast cancer prevention interventions.

Physical activity, mammographic density, and age-related lobular involution among premenopausal and postmenopausal women

OBJECTIVE

Physical activity may protect against breast cancer by modulating breast tissue composition. We evaluated the association of physical activity with two visual assessments of breast tissue composition-percentage of mammographic density (a radiologic observation) and age-related lobular involution (a histologic assessment).

METHODS

Among 164 premenopausal and postmenopausal women with breast cancer, physical activity (household, occupational, and recreational) performed during the year preceding the diagnosis was evaluated using a validated questionnaire. Percentage of mammographic density was assessed in the contralateral breast by a computer-assisted method. Age-related lobular involution was assessed in normal breast tissue on H&E-stained slides. Multivariate generalized linear models were used to assess associations by quartiles of physical activity.

RESULTS

Overall, we observed no significant association between total physical activity and percentage of mammographic density or degree of lobular involution. However, occupational physical activity was significantly positively associated with the predominant type I/no type III lobules among premenopausal women (last quartile: prevalence ratio [PR], 5.92; P(trend )= 0.04). Although total physical activity was positively associated with the predominant type I/no type III lobules among premenopausal women (last quartile: PR, 2.61; P(trend) = 0.08), an inverse association was observed among postmenopausal women (last quartile: PR, 0.44; P(trend) = 0.01). Higher levels of household physical activity were significantly associated with higher prevalence of lower mammographic density and complete involution among postmenopausal women (last quartile: PR, 1.21; P(trend) = 0.01).

CONCLUSIONS

Physical activity may be associated with less dense and more involuted breasts. Physical activity's effect on mammographic density or age-related lobular involution may mediate, in part, its protective effect against breast cancer.

Proteoglycans: Potential Agents in Mammographic Density and the Associated Breast Cancer Risk

Although increased mammographic density (MD) has been well established as a marker for increased breast cancer (BC) risk, its pathobiology is far from understood. Altered proteoglycan (PG) composition may underpin the physical properties of MD, and may contribute to the associated increase in BC risk. Numerous studies have investigated PGs, which are a major stromal matrix component, in relation to MD and BC and reported results that are sometimes discordant. Our review summarises these results and highlights discrepancies between PG associations with BC and MD, thus serving as a guide for identifying PGs that warrant further research towards developing chemo-preventive or therapeutic agents targeting preinvasive or invasive breast lesions, respectively.

Effect of menstrual cycle phase on background parenchymal uptake at molecular breast imaging

RATIONALE AND OBJECTIVES

The level of Tc-99m sestamibi uptake within normal fibroglandular tissue on molecular breast imaging (MBI), termed background parenchymal uptake (BPU), has been anecdotally observed to fluctuate with menstrual cycle. Our objective was to assess the impact of menstrual cycle phase on BPU appearance.

MATERIALS AND METHODS

Premenopausal volunteers who reported regular menstrual cycles and no exogenous hormone use were recruited to undergo serial MBI examinations during the follicular and luteal phase. A study radiologist, blinded to cycle phase, categorized BPU as photopenic, minimal mild, moderate, or marked. Change in BPU with cycle phase was determined, as well as correlations of BPU with mammographic density and hormone levels.

RESULTS

In 42 analyzable participants, high BPU (moderate or marked) was observed more often in luteal phase compared to follicular (P = .016). BPU did not change with phase in 30 of 42 participants (71%) and increased in the luteal phase compared to follicular in 12 (29%). High BPU was more frequent in dense breasts compared to nondense breasts at both the luteal (58% [15 of 26] vs. 13% [2 of 16], P = .004) and follicular phases (35% [9 of 26] vs. 6% [1 of 16], P = .061). Spearman correlation coefficients did not show any correlation of BPU with hormone levels measured at either cycle phase and suggested a weak correlation between change in BPU and changes in estrone and estradiol between phases.

CONCLUSIONS

We observed variable effects of menstrual cycle on BPU among our cohort of premenopausal women; however, when high BPU was observed, it was most frequently seen during the luteal phase compared to follicular phase and in women with dense breasts compared to nondense breasts.

Endogenous sex hormones and breast density in young women

BACKGROUND

Breast density is a strong risk factor for breast cancer and reflects epithelial and stromal content. Breast tissue is particularly sensitive to hormonal stimuli before it fully differentiates following the first full-term pregnancy. Few studies have examined associations between sex hormones and breast density among young women.

METHODS

We conducted a cross-sectional study among 180 women ages 25 to 29 years old who participated in the Dietary Intervention Study in Children 2006 Follow-up Study. Eighty-five percent of participants attended a clinic visit during their luteal phase of menstrual cycle. Magnetic resonance imaging measured the percentage of dense breast volume (%DBV), absolute dense breast volume (ADBV), and absolute nondense breast volume (ANDBV). Multiple-linear mixed-effect regression models were used to evaluate the association of sex hormones and sex hormone-binding globulin (SHBG) with %DBV, ADBV, and ANDBV.

RESULTS

Testosterone was significantly positively associated with %DBV and ADBV. The multivariable geometric mean of %DBV and ADBV across testosterone quartiles increased from 16.5% to 20.3% and from 68.6 to 82.3 cm(3), respectively (Ptrend ≤ 0.03). There was no association of %DBV or ADBV with estrogens, progesterone, non-SHBG-bound testosterone, or SHBG (Ptrend ≥ 0.27). Neither sex hormones nor SHBG was associated with ANDBV except progesterone; however, the progesterone result was nonsignificant in analysis restricted to women in the luteal phase.

CONCLUSIONS

These findings suggest a modest positive association between testosterone and breast density in young women.

IMPACT

Hormonal influences at critical periods may contribute to morphologic differences in the breast associated with breast cancer risk later in life.

Correlation of endogenous hormonal levels, fibroglandular tissue volume and percent density measured using 3D MRI during one menstrual cycle

BACKGROUND

We measured breast density (BD) on MRI and correlated with endogenous hormonal levels.

PATIENTS AND METHODS

Twenty-four premenopausal women received four weekly breast MRI. A blood sample was collected on the same day of MRI. BD was measured using a computer-based algorithm. The generalized estimation equation method was applied to model mean fibroglandular tissue volume (FV) and mean percent density (PD) from predictor variables including estradiol, progesterone, and week during a cycle.

RESULTS

In week 3, a borderline significant correlation between estradiol and PD (r = 0.43, P = 0.04), estradiol and FV (r = 0.40, P = 0.05) and between progesterone and FV (r = 0.42, P = 0.04) was noted. The FV and PD measured in weeks 4 and 1 were higher than in weeks 2 and 3, adjusted for variation in endogenous estradiol and progesterone, indicating that the hormone change could not account for the changes in density. No lag effect of endogenous hormone on the change of FV or PD was noted (all P-values > 0.05).

CONCLUSIONS

Our results showed that BD is not strongly associated with the endogenous hormone. Their association with breast cancer risk was likely coming from different mechanisms, and they should be considered as independent risk factors.

Diet across the Lifespan and the Association with Breast Density in Adulthood

Studies have shown inconsistent results regarding the association between dietary factors across the lifespan and breast density and breast cancer in women. Breast density is a strong risk factor for breast cancer, and the mechanism through which it influences cancer risk remains unclear. Breast density has been shown to be modifiable, potentially through dietary modifications. The goal of this paper is to summarize the current studies on diet and diet-related factors across all ages, determine which dietary factors show the strongest association with breast density, the most critical age of exposure, and identify future directions. We identified 28 studies, many of which are cross-sectional, and found that the strongest associations are among vitamin D, calcium, dietary fat, and alcohol in premenopausal women. Longitudinal studies with repeated dietary measures as well as the examination of overall diet over time are needed to confirm these findings.

Comparison of 3-point Dixon imaging and fuzzy C-means clustering methods for breast density measurement

PURPOSE

To assess two methods of fat and fibroglandular tissue (FGT) segmentation for measuring breast MRI FGT volume and FGT%, the volume percentage of FGT in the breast, in longitudinal studies.

MATERIALS AND METHODS

Nine premenopausal women provided one MRI per week for 4 weeks during a natural menstrual cycle for a total of 36 datasets. We compared a fuzzy c-means (FC) and a 3-point Dixon segmentation method for estimation of changes in FGT volume and FGT% across the menstrual cycle. We also assessed whether differences due to changes in positioning each week could be minimized by coregistration, i.e., the application of the breast boundary selected at one visit to images obtained at other visits.

RESULTS

FC and Dixon FGT volume were highly correlated (r = 0.93, P < 0.001), as was FC and Dixon FGT% (r = 0.86, P = 0.01), although Dixon measurements were on average 10-20% higher. Although FGT measured by both methods showed the expected pattern of increase during the menstrual cycle, the magnitude, and for one woman the direction, of change varied according to the method used. Measurements of FGT for coregistered images were in close agreement with those for which the boundaries were determined independently.

CONCLUSION

The method of segmentation of fat and FGT tissue may have an impact on the results of longitudinal studies of changes in breast MRI FGT.

Menstrual cycle-related fluctuations in breast density measured by using three-dimensional MR imaging

PURPOSE

To investigate the fluctuation of fibroglandular tissue volume (FV) and percentage of breast density (PD) during the menstrual cycle and compare with postmenopausal women by using three-dimensional magnetic resonance (MR)-based segmentation methods.

MATERIALS AND METHODS

This study was approved by the Institutional Review Board and was HIPAA compliant. Written informed consent was obtained. Thirty healthy female subjects, 24 premenopausal and six postmenopausal, were recruited. All subjects underwent MR imaging examination each week for 4 consecutive weeks. The breast volume (BV), FV, and PD were measured by two operators to evaluate interoperator variation. The fluctuation of each parameter measured over the course of the four examinations was evaluated on the basis of the coefficient of variation (CV).

RESULTS

The results from two operators showed a high Pearson correlation for BV (R(2) = 0.99), FV (R(2) = 0.98), and PD (R(2) = 0.96). The interoperator variation was 3% for BV and around 5%-6% for FV and PD. In the respective premenopausal and postmenopausal groups, the mean CV was 5.0% and 5.6% for BV, 7.6% and 4.2% for FV, and 7.1% and 6.0% for PD. The difference between premenopausal and postmenopausal groups was not significant (all P values > .05).

CONCLUSION

The fluctuation of breast density measured at MR imaging during a menstrual cycle was around 7%. The results may help the design and interpretation of future studies by using the change of breast density as a surrogate marker to evaluate the efficacy of hormone-modifying drugs for cancer treatment or cancer prevention.

Physical cues of ovulatory status: a failure to replicate enhanced facial attractiveness and reduced waist-to-hip ratio at high fertility

We investigated women's facial attractiveness and body shape as a function of menstrual cycle phase, with the expectation from previous research that both would be enhanced during the high fertile phase. To control for the effects of women's daily behaviors on their appearance and waistline, we visited 37 normally cycling women twice in their dorm, where we photographed and measured them at low and high fertile days of their cycle immediately upon their waking. Seventy-four judges from a separate institution chose, for each woman, the picture they thought was more attractive. We analyzed a subset of 20 women who, by forward counting, had a High Fertility visit between Days 10-13 and a Low Fertility visit between Days 20-23; and we also analyzed a subsample of 17 women who, by reverse counting, had a High Fertility visit on the days leading to ovulation and a Low Fertility visit one week after ovulation. In neither set of analyses were women's waist- to-hip ratios lower nearer ovulation, and in neither set were women's high fertile pictures chosen at an above-chance rate by either male or female judges. We did not find evidence that facial attractiveness and waist-to-hip ratio are reliable physical cues of ovulatory status.

Accuracy of screening mammography varies by week of menstrual cycle

PURPOSE

To investigate sensitivity, specificity, and cancer detection rate of screening mammography according to week of menstrual cycle among premenopausal women.

MATERIALS AND METHODS

In this institutional review board-approved HIPAA-compliant study, sensitivity, specificity, and cancer detection rate of 387,218 screening mammograms linked to 1283 breast cancers in premenopausal women according to week of menstrual cycle were studied by using prospectively collected information from the Breast Cancer Surveillance Consortium. Logistic regression analysis was used to test for differences in mammography performance according to week of menstrual cycle, adjusting for age and registry.

RESULTS

Overall, screening mammography performance did not differ according to week of menstrual cycle. However, when analyses were subdivided according to prior mammography, different patterns emerged. For the 66.6% of women who had undergone regular screening (mammography had been performed within the past 2 years), sensitivity was higher in week 1 (79.5%) than in subsequent weeks (week 2, 70.3%; week 3, 67.4%; week 4, 73.0%; P = .041). In the 17.8% of women who underwent mammography for the first time in this study, sensitivity tended to be lower during the follicular phase (week 1, 72.1%; week 2, 80.4%; week 3, 84.6%; week 4, 93.8%; P = .051). Sensitivity did not vary significantly by week in menstrual cycle in women who had undergone mammography more than 3 years earlier. There were no clinically meaningful differences in specificity or cancer detection rate.

CONCLUSION

Premenopausal women who undergo regular screening may benefit from higher sensitivity of mammography if they schedule screening mammography during the 1st week of their menstrual cycle.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100974/-/DC1.

Effects of isoflavones on breast density in pre- and post-menopausal women: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Isoflavones from soy and red clover exert modest hormonal effects in women, but the relevance to risk of breast cancer is unclear. The aim of this meta-analysis was to assess the effects of isoflavone-rich foods or supplements on a biomarker of breast cancer risk, women's mammographic density.

METHODS

Electronic searches were performed on The Cochrane Library, Medline and EMBASE (to June 2009), and reference lists and trial investigators were consulted to identify further studies. Randomized controlled trials (RCTs) of isoflavone-rich foods or supplements versus placebo with a duration of at least 6 months were included in our analysis. Inclusion/exclusion, data extraction and validity assessment were carried out independently in duplicate, and meta-analysis used to pool study results. Subgrouping, sensitivity analysis, assessment of heterogeneity and funnel plots were used to interpret the results.

RESULTS

Eight RCTs (1287 women) compared isoflavones with placebo for between 6 months and 3 years. Meta-analysis suggested no overall effect of dietary isoflavones on breast density in all women combined [mean difference (MD) 0.69%, 95% confidence interval (CI) -0.78 to 2.17] or post-menopausal women (MD -1.10%, 95% CI -3.22 to 1.03). However, there was a modest increase in mammographic density in premenopausal women (MD 1.83%, 95% CI 0.25-3.40) without heterogeneity but this effect was lost in one of three sensitivity analyses.

CONCLUSIONS

Isoflavone intake does not alter breast density in post-menopausal women, but may cause a small increase in breast density in premenopausal women. Larger, long-term trials are required to determine if these small effects are clinically relevant.

Cyclic Morphological Changes in the Beagle Mammary Gland

Interpretation of chemical-induced effects on the female beagle mammary gland can be difficult owing to the wide variation of normal glandular morphology. In this retrospective study, morphological features of the gland in four (proestrus, estrus, diestrus, and anestrus) phases of the cycle are described. The gland was quiescent (inactive) in proestrus and estrus. In diestrus, with the rise of progesterone, four (I–IV) distinct morphological changes were evident. In phase I, there was exuberant stromal and ductal proliferation. In phase II, there was early lobular development with branching ducts and alveolar proliferation. In phase III, there was an abundance of glandular tissue with large lobules containing secretory material, whereas phase IV had features of early regression, increased interlobular connective tissue, and eosinophilic secretions in distended ducts and acini. In early anestrus, ducts were distended, with eosinophilic secretions with alveolar regression, whereas regression was complete in late anestrus. Glandular morphology was slightly variable in the mammary chain within the same dog. Progesterone receptor expression was prominent in estrus and early diestrus, and peak estrogen receptor expression was noted in diestrus II. Expression of proliferation marker ki-67 was highest in diestrus I, followed by diestrus II. There was excellent concordance between the estrous stage and the glandular morphology.

Decrease in breast density in the contralateral normal breast of patients receiving neoadjuvant chemotherapy: MR imaging evaluation

PURPOSE

To investigate the change of breast density with quantitative magnetic resonance (MR) imaging in the contralateral normal breast of patients receiving neoadjuvant chemotherapy.

MATERIALS AND METHODS

This study was approved by the institutional review board and was HIPAA compliant. Informed consent was obtained. Fifty-four patients with breast cancer (mean age, 47 years; age range, 30-74 years) treated with NAC protocol and enrolled in a breast MR imaging research study were studied. The density in the contralateral normal breast was analyzed by using an MR imaging-based segmentation method. The effect of chemotherapy on the change of density following the doxorubicin and cyclophosphamide (AC) and the AC and taxane regimen was evaluated. The dependence on age was investigated by using a multivariate regression model.

RESULTS

In patients who underwent both AC and taxane follow-up, the mean percentage of change from the individual's baseline density was -10% (95% confidence interval: -12.8%, -7.2%) after AC and -12.7% (95% confidence interval: -16%, -9.4%) after AC and taxane. In patients who underwent both follow-up studies after one to two and four cycles of AC, the mean percentage of change was -9.4% (95% confidence interval: -13.5%, -5.3%) after one to two cycles of AC and -14.7% (95% confidence interval: -20.6%, -8.7%) after four cycles of AC. The percentage reduction of density was significantly dependent on age. Patients younger than 40 years had a greater reduction after chemotherapy than patients older than 55 years (P = .01).

CONCLUSION

By using three-dimensional MR imaging, patients receiving chemotherapy showed reduction of breast density, and the effects were significant after initial treatment with one to two cycles of the AC regimen.

Sex steroid metabolism polymorphisms and mammographic density in pre- and early perimenopausal women

Introduction

We examined the association between mammographic density and single-nucleotide polymorphisms (SNPs) in genes encoding CYP1A1, CYP1B1, aromatase, 17β-HSD, ESR1, and ESR2 in pre- and early perimenopausal white, African-American, Chinese, and Japanese women.

Methods

The Study of Women's Health Across the Nation is a longitudinal community-based cohort study. We analyzed data from 451 pre- and early perimenopausal participants of the ancillary SWAN Mammographic Density study for whom we had complete information regarding mammographic density, genotypes, and covariates. With multivariate linear regression, we examined the relation between percentage mammographic breast density (outcome) and each SNP (primary predictor), adjusting for age, race/ethnicity, parity, cigarette smoking, and body mass index (BMI).

Results

After multivariate adjustment, the CYP1B1 rs162555 CC genotype was associated with a 9.4% higher mammographic density than the TC/TT genotype (P = 0.04). The CYP19A1 rs936306 TT genotype was associated with 6.2% lower mammographic density than the TC/CC genotype (P = 0.02). The positive association between CYP1A1 rs2606345 and mammographic density was significantly stronger among participants with BMI greater than 30 kg/m² than among those with BMI less than 25 kg/m² (P_interaction = 0.05). Among white participants, the ESR1 rs2234693 CC genotype was associated with a 7.0% higher mammographic density than the CT/TT genotype (P = 0.01).

Conclusions

SNPs in certain genes encoding sex steroid metabolism enzymes and ESRs were associated with mammographic density. Because the encoded enzymes and ESR1 are expressed in breast tissue, these SNPs may influence breast cancer risk by altering mammographic density.

Differences in measured mammographic density in the menstrual cycle

BACKGROUND

In premenopausal women, the sensitivity of screening mammography for detecting breast cancer has been reported to be greater in the follicular phase than in the luteal phase of the menstrual cycle, which may be due to differences in mammographic density. To examine this possible effect, we compared mammographic density in premenopausal women who had mammograms at different phases of the menstrual cycle.

METHODS

We recruited premenopausal women ages 40 to 49 years from two mammography units in Toronto, recorded the first day of the last menstrual period (LMP) and measured mammographic density using Cumulus software. We classified the time of the mammography examination as having occurred in one of four intervals, 1 (first week after LMP), 2 (second week after LMP), 3 (third week after LMP) and 4 (>3 weeks after LMP), and compared mammographic density across intervals.

RESULTS

Of the 936 women included in the analysis, 620 were examined by film and 316 by digital mammography. There were small and statistically nonsignificant variations in breast dense, nondense area, and percent density over the menstrual cycle in women examined by film mammography. Marginally significant variation in percent density was observed in the digital subset due to significant differences in the amount of nondense tissue over the menstrual cycle.

CONCLUSION

Variations in mammographic density over the menstrual cycle were small and nonsignificant for women examined by either film or digital mammography. Thus, timing of mammography in menstrual cycle is unlikely to have a significant influence in breast cancer detection by screening mammography.

Fertility drug use and mammographic breast density in a mammography screening cohort of premenopausal women

The widespread use of ovulation-inducing drugs to enhance fertility has raised concerns about its potential effects on breast cancer risk, as ovarian stimulation is associated with increases in estrogen and progesterone levels. We investigated the short-term relation between fertility drug use and mammographic breast density, a strong marker of breast cancer risk, among participants in the Group Health Breast Cancer Screening Program. Data linkage with Group Health automated pharmacy records identified 104 premenopausal women < 50 years old who obtained a mammogram during 1996--2006, within 2 years after a fertility drug dispensing. Premenopausal nonusers of fertility drugs were matched to users by age, body mass index, age at first birth, family history of breast cancer, past use of birth control hormones, race, and education (n = 1005). All mammograms were categorized for density according to the Breast Imaging Reporting Data System as entirely fat, scattered fibroglandular, heterogeneously dense, or extremely dense. Density in fertility drug users was equally likely as in nonusers to be rated entirely fat [odds ratio (OR), 0.83; 95% confidence interval (95% CI), 0.18-3.71], heterogeneously dense (OR, 1.09; 95% CI, 0.64-1.85), or extremely dense (OR, 0.93; 95% CI, 0.48-1.78) compared with scattered fibroglandular. In analyses restricted to fertility drug users, each additional month after the date of dispensing was associated with a 13% (95% CI for the OR, 1.01-1.27) increased odds of being categorized as heterogeneously/extremely dense compared with entirely fat/scattered fibroglandular (P = 0.04). Our results indicate no overall association between fertility drug use and mammographic density, but provide evidence that density may be lower in women more recently dispensed a fertility drug.

Soy protein containing isoflavones and mammographic density in a randomized controlled trial in postmenopausal women

BACKGROUND

The relatively high dietary intake of soy in Asian countries has been hypothesized to, at least partly, explain the lower breast cancer incidence patterns in these countries compared with the Western world. The aim of the present study was to determine the effect of daily soy supplementation on mammographic density, one of the strongest known risk factors for breast cancer.

METHODS

A double-blind, randomized, controlled trial was conducted to compare the effects of soy protein intake containing 99 mg isoflavones daily with intake of milk protein (placebo) for the duration of 1 year. Two hundred and two Dutch postmenopausal women ages 60 to 75 years were randomized. Mammographic density was assessed using a quantitative computer-assisted method on digitized mammograms. Equol producer status was assessed in plasma provided at the final visit (soy group) or after a 3-day challenge with soy after the trial was finished (placebo group).

RESULTS

A total of 175 women completed the baseline visits and at least one follow-up visit and were included in the intention-to-treat analyses. For 126 women, both pre- and post-trial mammograms were available. Mammographic density decreased in both study arms, but the decrease did not differ significantly between intervention and placebo groups. Equol producer status did not modify the results.

CONCLUSION

The results of this trial do not support the hypothesis that a diet high in soy protein among postmenopausal women decreases mammographic density.

Exogenous and endogenous hormones, mammographic density and breast cancer risk: can mammographic density be considered an intermediate marker of risk?

Elevated mammographic density measures are a well-established, relatively strong risk factor for breast cancer development. A systematic review of prospective cohort studies and cross-sectional studies strikingly establishes parallels between the associations of combined postmenopausal estrogen and progestin replacement therapy with, on the one hand, mammographic densities and, on the other hand, breast cancer risk. Other parallel observations were the inverse associations of both mammographic density and breast cancer risk with the selective estrogen receptor modulator tamoxifen, and direct associations with prolactin. Paradoxically, however, high mammographic density has been found associated with higher risks of both estrogen- and progesterone-receptor positive (ER+/ PR+) and negative (ER-/PR-) breast cancers, while hormone replacement therapy (HRT) use, but also circulating (blood) levels of androgens, estrogens, and prolactin appear to be associated more specifically to the risk of ER+ tumors. The effects of aromatase inhibitors and gonadotropin-releasing hormone agonists on breast density, as well as on breast cancer risk, still require further investigation. Regarding circulating levels of insulin-like growth factor (IGF)-I or IGFBP-3, studies did not show fully consistent relationships with mammographic density measures and breast cancer risk. In view of these various findings, it is impossible, at present, to propose mammographic density measures as an intermediate risk-related phenotype, integrating the effects of exogenous and/or endogenous hormones on the risk of developing breast cancer.

Association between transillumination breast spectroscopy and quantitative mammographic features of the breast

Transillumination breast spectroscopy (TiBS) uses nonionizing optical radiation to gain information about tissue properties directly from the breast. TiBS measurements were obtained from 225 women with normal mammograms. Principal component analysis was used to reduce the spectral data set into four principal components and to generate four TiBS scores (t1-t4) for each woman. These components and scores represent light scattering, water, lipid, and hemoglobin content. Percent density, dense area, and nondense area were measured using Cumulus. The association between TiBS scores and quantitative mammographic features was analyzed using linear regression stratified by menopausal status and adjusted for body mass index. Among premenopausal women, t1 and t3 were significantly associated with percent density (beta t1 = -0.14, P = 0.04; beta t3 = -2.43, P < 0.0001), whereas t2 and t3 were significantly associated with dense area (beta t2 = -1.57, P < 0.0001; beta t3 = -2.54, P < 0.0001). Among postmenopausal women, t1, t3, and t4 were significantly associated with percent density (beta t1 = -0.30, P < 0.0001; beta t3 = -2.51, P < 0.0001; beta t4 = 4.75, P < 0.0001) and dense area (beta t1 = -0.19, P = 0.004; beta t3 = -2.13, P = 0.002; beta t4 = 5.02, P < 0.0001). Scores t2 and t4 were also significantly correlated with age among postmenopausal women (rt2 = 0.41 and rt4 = -0.36). Given the association with quantitative mammographic features and tissue changes related to age and menopause, TiBS scores may prove useful as intermediate markers in studies of breast cancer etiology and prevention.

Effect of raloxifene on mammographic density and breast magnetic resonance imaging in premenopausal women at increased risk for breast cancer

BACKGROUND

Mammographic density is a risk factor for breast cancer. Mammographic density and breast magnetic resonance imaging (MRI) volume (MRIV) assess the amount of fibroglandular tissue in the breast. Mammographic density and MRIV can be modulated with hormonal interventions, suggesting that these imaging modalities may be useful as surrogate endpoint biomarkers for breast cancer chemoprevention trials. We evaluated the effect of raloxifene on mammographic density and MRIV in premenopausal women at increased risk for breast cancer.

METHODS

Mammograms and MRI were obtained at baseline and after 1 and 2 years of 60 mg raloxifene by mouth daily for 27 premenopausal women. Mammographic percent dense area was calculated using a semiquantitative thresholding technique. T(1)-weighted spoiled gradient-echo MRI with fat suppression was used to determine breast MRIV using a semiautomatic method. Mean change in mammographic density and median change in MRIV were assessed by the Wilcoxon signed-rank test.

RESULTS

No significant change in mammographic density was seen after treatment with raloxifene. Mean change after 1 year was 1% [95% confidence interval (95% CI), -3 to +5] and after 2 years was 1% (95% CI, -2 to +5). MRIV decreased on raloxifene. Median relative change in MRIV after 1 year was -17% (95% CI, -28 to -9; P = 0.0017) and after 2 years was -16% (95% CI, -31 to -4; P = 0.0004).

CONCLUSIONS

In high-risk premenopausal women, mammographic density did not change on raloxifene, whereas MRIV significantly declined. Our findings suggest that MRIV is a promising surrogate biomarker in premenopausal women at increased risk for breast cancer and should be investigated further in breast cancer prevention trials.

Mammographic density. Measurement of mammographic density

Mammographic density has been strongly associated with increased risk of breast cancer. Furthermore, density is inversely correlated with the accuracy of mammography and, therefore, a measurement of density conveys information about the difficulty of detecting cancer in a mammogram. Initial methods for assessing mammographic density were entirely subjective and qualitative; however, in the past few years methods have been developed to provide more objective and quantitative density measurements. Research is now underway to create and validate techniques for volumetric measurement of density. It is also possible to measure breast density with other imaging modalities, such as ultrasound and MRI, which do not require the use of ionizing radiation and may, therefore, be more suitable for use in young women or where it is desirable to perform measurements more frequently. In this article, the techniques for measurement of density are reviewed and some consideration is given to their strengths and limitations.