Aromatase inhibitors and mammographic breast density in postmenopausal women receiving hormone therapy

Mammographic Density Reduction is Associated to the Prognosis in Asian Breast Cancer Patients Receiving Hormone Therapy

INTRODUCTION

Using mammographic density as a significant biomarker for predicting prognosis in adjuvant hormone therapy patients is controversial due to the conflicting results of recent studies. This study aimed to evaluate hormone therapy-induced mammographic density reduction and its association with prognosis in Taiwanese patients.

METHODS

In this retrospective study, 1941 patients with breast cancer were screened, and 399 patients with estrogen receptor-positive breast cancer who received adjuvant hormone therapy were enrolled. The mammographic density was measured using a fully automatic estimation procedure based on full-field digital mammography. The prognosis included relapse and metastasis during treatment follow-up. The Kaplan-Meier method and Cox proportional hazards model were used for disease-free survival analysis.

RESULTS

A mammographic density reduction rate >20.8%, measured preoperatively and after receiving hormone therapy from 12-18 months, was a significant threshold for predicting prognosis in patients with breast cancer. The disease-free survival rate was significantly higher in patients whose mammographic density reduction rate was >20.8% (P = .048).

CONCLUSION

This study's findings could help estimate the prognosis for patients with breast cancer and may improve the quality of adjuvant hormone therapy after enlarging the study cohort in the future.

Breast Cancer Risk with Progestin Subdermal Implants: A Challenge in Patients Counseling

There is a steady global rise in the use of progestin subdermal implants, where use has increased by more than 20 times in the past two decades. BC risk has been reported with the older progestin only methods such as oral pills, injectables, and intrauterine devices, however, little is known about the risk with subdermal implants. In this review, we aim to update clinicians and researchers on the current evidence to support patient counseling and to inform future research directions. The available evidence of the association between the use of progestin subdermal implants and BC risk is discussed. We provide an overview of the potential role of endogenous progesterone in BC development. The chemical structure and molecular targets of synthetic progestins of relevance are summarized together with the preclinical and clinical evidence on their association with BC risk. We review all studies that investigated the action of the specific progestins included in subdermal implants. As well, we discuss the potential effect of the use of subdermal implants in women at increased BC risk, including carriers of BC susceptibility genetic mutations.

Mammographic Density Distribution of Healthy Taiwanese Women and its Naturally Decreasing Trend with Age

We analysed typical mammographic density (MD) distributions of healthy Taiwanese women to augment existing knowledge, clarify cancer risks, and focus public health efforts. From January 2011 to December 2015, 88,193 digital mammograms were obtained from 69,330 healthy Taiwanese women (average, 1.27 mammograms each). MD measurements included dense volume (DV) and volumetric density percentage (VPD) and were quantified by fully automated volumetric density estimation and Box-Cox normalization. Prediction of the declining MD trend was estimated using curve fitting and a rational model. Normalized DV and VPD Lowess curves demonstrated similar but non-identical distributions. In high-density grade participants, the VPD increased from 12.45% in the 35-39-year group to 13.29% in the 65-69-year group but only from 5.21% to 8.47% in low-density participants. Regarding the decreased cumulative VPD percentage, the mean MD declined from 12.79% to 19.31% in the 45-50-year group versus the 50-55-year group. The large MD decrease in the fifth decade in this present study was similar to previous observations of Western women. Obtaining an MD distribution model with age improves the understanding of breast density trends and age variations and provides a reference for future studies on associations between MD and cancer risk.

Reproducible automated breast density measure with no ionizing radiation using fat-water decomposition MRI

BACKGROUND

Increased breast density is a significant independent risk factor for breast cancer, and recent studies show that this risk is modifiable. Hence, breast density measures sensitive to small changes are desired.

PURPOSE

Utilizing fat-water decomposition MRI, we propose an automated, reproducible breast density measurement, which is nonionizing and directly comparable to mammographic density (MD).

STUDY TYPE

Retrospective study.

POPULATION

The study included two sample sets of breast cancer patients enrolled in a clinical trial, for concordance analysis with MD (40 patients) and reproducibility analysis (10 patients).

FIELD STRENGTH/SEQUENCE

The majority of MRI scans (59 scans) were performed with a 1.5T GE Signa scanner using radial IDEAL-GRASE sequence, while the remaining (seven scans) were performed with a 3T Siemens Skyra using 3D Cartesian 6-echo GRE sequence with a similar fat-water separation technique.

ASSESSMENT

After automated breast segmentation, breast density was calculated using FraGW, a new measure developed to reliably reflect the amount of fibroglandular tissue and total water content in the entire breast. Based on its concordance with MD, FraGW was calibrated to MR-based breast density (MRD) to be comparable to MD. A previous breast density measurement, Fra80-the ratio of breast voxels with <80% fat fraction-was also calculated for comparison with FraGW.

STATISTICAL TESTS

Pearson correlation was performed between MD (reference standard) and FraGW (and Fra80). Test-retest reproducibility of MRD was evaluated using the difference between test-retest measures (Δ_1-2 ) and intraclass correlation coefficient (ICC).

RESULTS

Both FraGW and Fra80 were strongly correlated with MD (Pearson ρ: 0.96 vs. 0.90, both P < 0.0001). MRD converted from FraGW showed higher test-retest reproducibility (Δ_1-2 variation: 1.1% ± 1.2%; ICC: 0.99) compared to MD itself (literature intrareader ICC ≤0.96) and Fra80.

DATA CONCLUSION

The proposed MRD is directly comparable with MD and highly reproducible, which enables the early detection of small breast density changes and treatment response.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;48:971-981.

Longitudinal Changes in Volumetric Breast Density with Tamoxifen and Aromatase Inhibitors

Background: Reductions in breast density with tamoxifen and aromatase inhibitors may be an intermediate marker of treatment response. We compare changes in volumetric breast density among breast cancer cases using tamoxifen or aromatase inhibitors (AI) to untreated women without breast cancer.Methods: Breast cancer cases with a digital mammogram prior to diagnosis and after initiation of tamoxifen (n = 366) or AI (n = 403) and a sample of controls (n = 2170) were identified from the Mayo Clinic Mammography Practice and San Francisco Mammography Registry. Volumetric percent density (VPD) and dense breast volume (DV) were measured using Volpara (Matakina Technology) and Quantra (Hologic) software. Linear regression estimated the effect of treatment on annualized changes in density.Results: Premenopausal women using tamoxifen experienced annualized declines in VPD of 1.17% to 1.70% compared with 0.30% to 0.56% for controls and declines in DV of 7.43 to 15.13 cm³ compared with 0.28 to 0.63 cm³ in controls, for Volpara and Quantra, respectively. The greatest reductions were observed among women with ≥10% baseline density. Postmenopausal AI users had greater declines in VPD than controls (Volpara P = 0.02; Quantra P = 0.03), and reductions were greatest among women with ≥10% baseline density. Declines in VPD among postmenopausal women using tamoxifen were only statistically greater than controls when measured with Quantra.Conclusions: Automated software can detect volumetric breast density changes among women on tamoxifen and AI.Impact: If declines in volumetric density predict breast cancer outcomes, these measures may be used as interim prognostic indicators. Cancer Epidemiol Biomarkers Prev; 26(6); 930-7. ©2017 AACR.

Relationship Between Breast Density and Selective Estrogen-Receptor Modulators, Aromatase Inhibitors, Physical Activity, and Diet: A Systematic Review

Background Lower breast density (BD) is associated with lower risk of breast cancer and may serve as a biomarker for the efficacy of chemopreventive strategies. This review explores parameters that are thought to be associated with lower BD. We conducted a systematic review of articles published to date using the PRISMA strategy. Articles that assessed change in BD with estrogen-receptor modulators (tamoxifene [TAM], raloxifene [RLX], and tibolone) and aromatase inhibitors (AIs), as well as cross-sectional and longitudinal studies (LSs) that assessed association between BD and physical activity (PA) or diet were reviewed. Results Ten studies assessed change in BD with TAM; all reported TAM-mediated BD decreases. Change in BD with RLX was assessed by 11 studies; 3 reported a reduction in BD. Effect of tibolone was assessed by 5 RCTs; only 1 reported change in BD. AI-mediated BD reduction was reported by 3 out of 10 studies. The association between PA and BD was assessed by 21 studies; 4 reported an inverse association. The relationship between diet and BD was assessed in 34 studies. All studies on calcium and vitamin D as well as vegetable intake reported an inverse association with BD in premenopausal women. Two RCTs demonstrated BD reduction with a low-fat, high-carbohydrate intervention. Conclusion TAM induces BD reduction; however, the effect of RLX, tibolone, and AIs on BD is unclear. Although data on association between diet and BD in adulthood are contradictory, intake of vegetables, vitamin D, and calcium appear to be associated with lower BD in premenopausal women.

Aromatase inhibitors for prevention of breast cancer in postmenopausal women: a narrative review

OBJECTIVE

The increasing incidence of breast cancer (BC) worldwide has resulted in widespread interest in primary prevention therapies. A number of large randomized trials have shown that selective estrogen receptor modulators can reduce the relative risk for BC by 30% to 40% in high-risk women. In early-stage BC, aromatase inhibitors (AIs) showed a 35% relative reduction in the risk of contralateral BCs compared with tamoxifen. In this narrative review, we discuss the role of AIs in the primary prevention of BC and novel research on combination hormone therapy-medical therapy for the primary prevention of BC.

METHODS

Using PubMed/Medline, we comprehensively searched for studies of BC primary prevention using AIs, including studies of novel methods of prevention using combination hormone therapy-BC prevention.

RESULTS

Two large multicenter, prospective, randomized, placebo-controlled trials have evaluated AIs--anastrozole (International Breast Cancer Intervention Study II) and exemestane (Mammary Prevention 3)--for BC risk reduction in women at increased risk for BC, which we summarize. We identified five studies (three completed and two ongoing) of combination AI-hormone therapy that are undergoing investigation for BC risk reduction.

CONCLUSIONS

AIs are effective at BC risk reduction, although long-term follow-up data are required to assess whether this risk reduction will result in reduced mortality. Combination hormone therapy-AI for BC risk reduction is experimental and warrants further investigation.

Effect of preventive hormonal therapy on breast density: a systematic qualitative review

Breast density (BD) is recognized as one of the strongest independent risk factors of breast cancer (BC). Unlike most other risk factors, BD can be modified, suggesting that it may be a biomarker for preventive interventions. We conducted a qualitative systematic review to address the effect of preventive hormonal therapy on BD. Among the 26 relevant studies, 10 assessed the effect of tamoxifen on BD (TAM: n = 2 877), 9 that of raloxifene (RLX: n = 1 544), and 7 that of aromatase inhibitors (AI: n = 416). The studies were characterized by a large heterogeneity in designs and in methods of BD measurement. BD could be reduced by TAM (10 studies/10). However, the effect of RLX and AI on BD remains unclear due to conflicting results between studies. Consequently, it is crucial to develop practical, accurate, and reproducible methods of measurement in order to be able to compare the effect of preventive hormonal agents on BD and to determine whether change in BD can be used as a predictor of response to therapy.

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.

Mammographic breast density response to aromatase inhibition

PURPOSE

Mammographic breast density (MBD) is decreased by tamoxifen, but the effect of aromatase inhibitors is less clear.

EXPERIMENTAL DESIGN

We enrolled early-stage postmenopausal patients with breast cancer initiating adjuvant aromatase inhibitor therapy and ascertained mammograms before and at an average 10 months of aromatase inhibitor therapy. We matched cases to healthy postmenopausal women (controls) from a large mammography screening cohort on age, baseline body mass index, baseline MBD, and interval between mammograms. We estimated change in MBD using a computer-assisted thresholding program (Cumulus) and compared differences between cases and matched controls.

RESULTS

In predominantly White women (96%), we found 14% of the 387 eligible cases had a MBD reduction of at least 5% after an average of 10 months of aromatase inhibitor therapy. MBD reductions were associated with higher baseline MBD, aromatase inhibitor use for more than 12 months, and prior postmenopausal hormone use. Comparing each case with her matched control, there was no evidence of an association of change in MBD with aromatase inhibitor therapy [median case-control difference among 369 pairs was -0.1% (10th and 90th percentile: -5.9%, 5.2%) P = 0.51]. Case-control differences were similar by type of aromatase inhibitor (P's 0.41 and 0.56); prior use of postmenopausal hormones (P = 0.85); baseline MBD (P = 0.55); and length of aromatase inhibitor therapy (P = 0.08).

CONCLUSIONS

In postmenopausal women treated with aromatase inhibitors, 14% of cases had a MBD reduction of more than 5%, but these decreases did not differ from matched controls. These data suggest that MBD is not a clinically useful biomarker for predicting the value of aromatase inhibitor therapy in White postmenopausal women.

Impact of tamoxifen on amount of fibroglandular tissue, background parenchymal enhancement, and cysts on breast magnetic resonance imaging

The objective of this study was to evaluate the impact of tamoxifen treatment on amount of fibroglandular tissue (FGT), background parenchymal enhancement (BPE), and cysts on breast MRI. Retrospective search identified 96 women with breast cancer who had a breast MRI both before and during adjuvant tamoxifen therapy between 2002 and 2008. After exclusion of all irradiated breasts, 88 women were eligible. Two readers blinded to tamoxifen treatment status independently rated level of BPE, amount of FGT, and cysts using a 4-point categorical scale: BPE--Minimal, Mild, Moderate, Marked; FGT--Fatty, Scattered, Heterogeneously Dense (HD), Dense; Cysts--Minimal, Mild, Moderate, Marked. A consensus interpretation was reached in cases of disagreement. During tamoxifen, there was a significant shift from higher to lower degree BPE, cysts, and FGT compared with before tamoxifen. BPE, cysts and FGT decreased in 68% (60/88), 38% (33/88), and 40% (35/88) of women during tamoxifen (p<0.001 for all measures). After the exclusion of all cases with minimal BPE, cysts, or FGT on the pre-tamoxifen MRI, the percentage of women demonstrating a decrease in these factors increased to 81% (60/74), 77% (33/43), and 41% (35/86), respectively. Exclusion of patients treated with chemotherapy did not substantially change these results. The percentage of women with decreases in FGT and cysts increased with greater duration on tamoxifen, whereas decreases in BPE were detected early in treatment (<90 days) and did not change substantially with longer duration on tamoxifen. A significant association exists between treatment with tamoxifen and decreases in BPE, cysts, and FGT on breast MRI.

The effect of acute aromatase inhibition on breast parenchymal enhancement in magnetic resonance imaging: a prospective pilot clinical trial

OBJECTIVE

The breast is highly hormonally sensitive especially to the sex steroid hormone estrogen. Both physiological and iatrogenic steroid hormone modifications could affect how the breast tissue may appear in breast imaging techniques. We hypothesized that estrogen deprivation therapy could reduce breast nonspecific enhancement on magnetic resonance imaging (MRI).

METHODS

This study was a prospective pilot phase II clinical trial. The study was approved by Health Canada and the institutional research ethics board, and participants signed informed consent forms. Sixteen healthy postmenopausal women were enrolled, and 14 completed the study. Baseline breast MRI was done followed 1 month later by administration of a high-dose aromatase inhibitor (letrozole 12.5 mg/day) for 3 successive days before a second breast MRI. Background breast parenchymal enhancement was compared between the pretreatment and posttreatment studies.

RESULTS

There was a statistically significant reduction of the average background breast enhancement after treatment with aromatase inhibitors compared with baseline MRI. Of particular interest, specific areas of benign breast enhancement were reduced after aromatase inhibitor treatment. No significant adverse effects were recorded using this relatively high dose of the aromatase inhibitors.

CONCLUSIONS

This preliminary study provided evidence that aromatase inhibitors could reduce the parenchymal background enhancement of benign breast tissue during MRI and may improve the specificity of the technique.

Breast density change as a predictive surrogate for response to adjuvant endocrine therapy in hormone receptor positive breast cancer

Introduction

Anti-estrogen therapy has been shown to reduce mammographic breast density (MD). We hypothesized that a short-term change in breast density may be a surrogate biomarker predicting response to adjuvant endocrine therapy (ET) in breast cancer.

Methods

We analyzed data for 1,065 estrogen receptor (ER)-positive breast cancer patients who underwent surgery between 2003 and 2006 and received at least 2 years of ET, including tamoxifen and aromatase inhibitors. MD was measured using Cumulus software 4.0 and expressed as a percentage. MD reduction (MDR) was defined as the absolute difference in MD of mammograms taken preoperatively and 8-20 months after the start of ET.

Results

At a median follow-up of 68.8 months, the overall breast cancer recurrence rate was 7.5% (80/1065). Mean MDR was 5.9% (range, -17.2% to 36.9%). Logistic regression analysis showed that age < 50 years, high preoperative MD, and long interval between start of ET to follow-up mammogram were significantly associated with larger MDR (p < 0.05). In a survival analysis, tumor size, lymph node positivity, high Ki-67 (≥ 10%), and low MDR were independent factors significantly associated with recurrence-free survival (p < 0.05). Compared with the group showing the greatest MDR (≥ 10%), the hazard ratios for MDRs of 5-10%, 0-5%, and < 0% were 1.33, 1.92, and 2.26, respectively.

Conclusions

MD change during short-term use of adjuvant ET was a significant predictor of long-term recurrence in women with ER-positive breast cancer. Effective treatment strategies are urgently needed in patients with low MDR despite about 1 year of ET.

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.

Aromatase immunoreactivity is increased in mammographically dense regions of the breast

Mammographic breast density (MBD) is one of the strongest risk factors for breast cancer. Unfortunately, the biologic basis underlying this association is unknown. This study compared aromatase expression or immunoreactivity (IR) in core biopsies from mammographically dense versus non-dense regions of the breast to examine whether estrogen synthesis in the breast is associated with MBD and one possible mechanism through which MBD may influence breast cancer. Eligible participants were 40+ years, had a screening mammogram with visible MBD and no prior 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. Immunostaining for aromatase employed the streptavidin-biotin amplification method and #677 mouse monoclonal antibody. Aromatase IR was scored in terms of extent and intensity of staining for each cell type (stroma, epithelium, adipocytes) on histologic sections. A modified histological H-score provided quantitation of aromatase IR in each cell type and overall. Repeated measure analyses evaluated average differences (β(H)) in H-score in dense versus non-dense tissue within and across cell types. Forty-nine women with mean age 50 years (range: 40-82), participated. Aromatase IR was increased in dense (vs. non-dense) tissue in both the stroma (β(H) = 0.58) and epithelium (β(H) = 0.12) (P < 0.01). Adipocytes from non-dense tissue, however, had a greater IR compared to those from dense tissue (β(H) = -0.24, P < 0.01). An overall H-score which integrated results from all cell types demonstrated that aromatase IR was twice as great for dense (mean H-score = 0.90, SD = 0.53) versus non-dense (mean H-score = 0.45, SD = 0.39) breast tissue (β(H) = 0.45; P < 0.001). Overall, aromatase IR was greater for mammographically dense versus non-dense tissue and may partly explain how MBD influences breast cancer.