BACKGROUND: microRNAs (miRNAs) are small, noncoding RNA molecules, functioning either as oncogenes or tumor suppressor genes. SNPs in miRNAs might modify the expression of genes associated with miRNAs, enhancing susceptibility to breast cancer. Both miRNA-146a (rs2910164) and miRNA-196a (rs11614913) are identified and significantly associated with breast cancer risk in several ethnicities, but remains unexplored in Khyber Pakhtunkhwa population of Pakistan.
METHODS: This study was aimed to check the relation of selected SNPs with breast cancer risk. The research cohort included 100 breast cancer patients and 100 healthy controls. All the participants were subjected for DNA extraction followed by T-ARMS PCR and gel electrophoresis.
RESULTS: The results revealed a strong association between risk allele (G) of miRNA-146a and increased risk of breast cancer (OR = 2.04, P = 0.0006). Similarly, heterozygous and mutant genotypes also indicated high risk and significant association with breast cancer risk (CG; OR = 0.51, 9 P = 0.0001) (GG; OR = 3.76, P = 0.04). However, risk allele (T) of miRNA-196a (rs11614913) failed to exhibit significant association with breast cancer risk (OR = 0.92 P = 0.68). Similarly, the heterozygous and mutant genotype did not show significant association with breast cancer risk (CT; OR = 0.52, P = 0.125 (TT; OR = 0.88, P = 0.84). Furthermore, miRNA-146a (rs2910164) and miRNA-196a (rs11614913) polymorphisms exhibited non-significant associations with family history (P = 0.34, P = 0.77), PR status (P = 0.310, P = 0.397), ER status (P = 0.992, P = 0.981), nodal status (P = 0.86, P = 0.90), and menstrual status (P = 0.97, P = 0.09). Notably, miRNA-196a showed a significant association with the metastasis group (P = 0.010) and cancer stages (P = 0.047).
CONCLUSIONS: In conclusion, this study highlights the association of miRNA-146a (rs2910164) polymorphism with breast cancer risk but suggested non-significant association of miRNA-196a (rs11614913) with breast cancer risk. However, these findings need to be confirmed through larger data set for more accurate result.

Breast density is a strong intermediate endpoint to investigate the association between early-life exposures and breast cancer risk. This study investigates the association between early-life growth and breast density in young adult women measured using Optical Breast Spectroscopy (OBS) and Dual X-ray Absorptiometry (DXA). OBS measurements were obtained for 536 female Raine Cohort Study participants at ages 27-28, with 268 completing DXA measurements. Participants with three or more height and weight measurements from ages 8 to 22 were used to generate linear growth curves for height, weight and body mass index (BMI) using SITAR modelling. Three growth parameters (size, velocity and timing) were examined for association with breast density measures, adjusting for potential confounders. Women who reached their peak height rapidly (velocity) and later in adolescence (timing) had lower OBS-breast density. Overall, women who were taller (size) had higher OBS-breast density. For weight, women who grew quickly (velocity) and later in adolescence (timing) had higher absolute DXA-breast density. Overall, weight (size) was also inversely associated with absolute DXA-breast density, as was BMI. These findings provide new evidence that adolescent growth is associated with breast density measures in young adult women, suggesting potential mediation pathways for breast cancer risk in later life.

Obesity is a risk factor for postmenopausal breast cancer (BC), and evidence suggests a role for adiponectin in the relationship between obesity and BC. We investigated whether adiponectin or other biomarkers mediate the effect of body mass index (BMI) on postmenopausal BC risk in a cohort study nested in the IBIS-II Prevention Trial. We measured adiponectin, leptin, IGF-I, IGFBP-1, high-sensitivity C-reactive protein, glycemia, insulin, HOMA-IR index, and SHBG in baseline and 12-month serum samples from 123 cases and 302 matched controls in the placebo arm of the IBIS-II Prevention trial. We conducted the main mediation analysis considering baseline BMI as an exposure and the 12-month adiponectin increase as a mediator after adjustment for the Tyrer-Cuzick score and the lipid-lowering medications/supplements use. In the multivariable Cox model, both the 12-month adiponectin increase (HR, 0.60; 95%CI, 0.36-1.00) and BMI were associated with BC risk (HR, 1.05; 95%CI, 1.00-1.09), with a 40% reduction in women with a 12-month increase in adiponectin. A significantly higher cumulative hazard of BC events was observed in obese women (BMI > 30) with decreased adiponectin (p = 0.0087). No mediating effect of the adiponectin increase on the total effect of BMI on BC risk was observed (natural indirect effect: HR, 1.00; 95%CI, 0.98-1.02). Raising adiponectin levels might be an attractive target for postmenopausal BC prevention.

BACKGROUND: The effect of gender-affirming testosterone therapy (TT) on breast cancer risk is unclear. This study investigated the association between TT and breast tissue composition and breast tissue density in trans masculine individuals (TMIs).
METHODS: Of the 444 TMIs who underwent chest-contouring surgeries between 2013 and 2019, breast tissue composition was assessed in 425 TMIs by the pathologists (categories of lobular atrophy and stromal composition) and using our automated deep-learning algorithm (% epithelium, % fibrous stroma, and % fat). Forty-two out of 444 TMIs had mammography prior to surgery and their breast tissue density was read by a radiologist. Mammography digital files, available for 25/42 TMIs, were analyzed using the LIBRA software to obtain percent density, absolute dense area, and absolute non-dense area. Linear regression was used to describe the associations between duration of TT use and breast tissue composition or breast tissue density measures, while adjusting for potential confounders. Analyses stratified by body mass index were also conducted.
RESULTS: Longer duration of TT use was associated with increasing degrees of lobular atrophy (p < 0.001) but not fibrous content (p = 0.82). Every 6 months of TT was associated with decreasing amounts of epithelium (exp(β) = 0.97, 95% CI 0.95,0.98, adj p = 0.005) and fibrous stroma (exp(β) = 0.99, 95% CI 0.98,1.00, adj p = 0.05), but not fat (exp(β) = 1.01, 95%CI 0.98,1.05, adj p = 0.39). The effect of TT on breast epithelium was attenuated in overweight/obese TMIs (exp(β) = 0.98, 95% CI 0.95,1.01, adj p = 0.14). When comparing TT users versus non-users, TT users had 28% less epithelium (exp(β) = 0.72, 95% CI 0.58,0.90, adj p = 0.003). There was no association between TT and radiologist\'s breast density assessment (p = 0.58) or LIBRA measurements (p > 0.05).
CONCLUSIONS: TT decreases breast epithelium, but this effect is attenuated in overweight/obese TMIs. TT has the potential to affect the breast cancer risk of TMIs. Further studies are warranted to elucidate the effect of TT on breast density and breast cancer risk.

BACKGROUND: High-risk programs provide recommendations for surveillance/risk reduction for women at elevated risk for breast cancer development. This study evaluated the impact of high-risk surveillance program participation on clinicopathologic breast cancer features at the time of diagnosis.
METHODS: Women followed in the authors\' high-risk program (high-risk cohort [HRC]) with a diagnosis of breast cancer from January 2015 to June 2021 were identified and compared with the general population of women undergoing breast cancer surgery at Memorial Sloan Kettering Cancer Center (MSK; general cohort [GC]) during the same period. Patient and tumor factors were collected. Clinicopathologic features were compared between the two cohorts and in a subset of women with a family history of known BRCA mutation.
RESULTS: The study compared 255 women in the HRC with 9342 women in the GC. The HRC patients were slightly older and more likely to be white and have family history than the GC patients. The HRC patients also were more likely to present with DCIS (41 % vs 23 %; p < 0.001), to have smaller invasive tumors (pT1: 100 % vs 77 %; p < 0.001), and to be pN0 (95 % vs 81 %; p < 0.001). The HRC patients had more invasive triple-negative tumors (p = 0.01) and underwent less axillary surgery (p < 0.001), systemic therapy (p < 0.001), and radiotherapy (p = 0.002). Among those with a known BRCA mutation, significantly more women in the HRC underwent screening mammography (75 % vs 40 %; p < 0.001) or magnetic resonance imaging (MRI: 82 % vs 9.9 %; p < 0.001) in the 12 months before diagnosis.
CONCLUSIONS: Women followed in a high-risk screening program have disease diagnosed at an earlier stage and therefore require less-intensive breast cancer treatment than women presenting to a cancer center at the time of diagnosis. Identification of high-risk women and implementation of increased surveillance protocols are vital to improving outcomes.

In DCE-MRI, the degree of contrast uptake in normal fibroglandular tissue, i.e., background parenchymal enhancement (BPE), is a crucial biomarker linked to breast cancer risk and treatment outcome. In accordance with the Breast Imaging Reporting & Data System (BI-RADS), it should be visually classified into four classes. The susceptibility of such an assessment to inter-reader variability highlights the urgent need for a standardized classification algorithm. In this retrospective study, the first post-contrast subtraction images for 27 healthy female subjects were included. The BPE was classified slice-wise by two expert radiologists. The extraction of radiomic features from segmented BPE was followed by dataset splitting and dimensionality reduction. The latent representations were then utilized as inputs to a deep neural network classifying BPE into BI-RADS classes. The network\'s predictions were elucidated at the radiomic feature level with Shapley values. The deep neural network achieved a BPE classification accuracy of 84 ± 2% (p-value < 0.00001). Most of the misclassifications involved adjacent classes. Different radiomic features were decisive for the prediction of each BPE class underlying the complexity of the decision boundaries. A highly precise and explainable pipeline for BPE classification was achieved without user- or algorithm-dependent radiomic feature selection.

OBJECTIVE: To assess the association of a polygenic risk score (PRS) for functional genetic variants with the risk of developing breast cancer.
METHODS: Summary data-based Mendelian randomization (SMR) and heterogeneity in dependent instruments (HEIDI) were used to identify breast cancer risk variants associated with gene expression and DNA methylation levels. A new SMR-based PRS was computed from the identified variants (functional PRS) and compared to an established 313-variant breast cancer PRS (GWAS PRS). The two scores were evaluated in 3560 breast cancer cases and 3383 non-cancer controls and also in a prospective study (n = 10,213) comprising 418 cases.
RESULTS: We identified 149 variants showing pleiotropic association with breast cancer risk (eQTLHEIDI > 0.05 = 9, mQTLHEIDI > 0.05 = 165). The discriminatory ability of the functional PRS (AUCcontinuous [95% CI]: 0.540 [0.526 to 0.553]) was found to be lower than that of the GWAS PRS (AUCcontinuous [95% CI]: 0.609 [0.596 to 0.622]). Even when utilizing 457 distinct variants from both the functional and GWAS PRS, the combined discriminatory performance remained below that of the GWAS PRS (AUCcontinuous, combined [95% CI]: 0.561 [0.548 to 0.575]). A binary high/low-risk classification based on the 80th centile PRS in controls revealed a 6% increase in cases using the GWAS PRS compared to the functional PRS. The functional PRS identified an additional 12% of high-risk cases but also led to a 13% increase in high-risk classification among controls. Similar findings were observed in the SCHS prospective cohort, where the GWAS PRS outperformed the functional PRS, and the highest-performing PRS, a combined model, did not significantly improve over the GWAS PRS.
CONCLUSIONS: While this study identified potentially functional variants associated with breast cancer risk, their inclusion did not substantially enhance the predictive accuracy of the GWAS PRS.

There is evidence suggesting that endocrine interventions such as hormone replacement therapy and hormonal contraception can increase breast cancer (BC) risk. Sexual steroid hormones like estrogens have long been known for their adverse effects on BC development and progression via binding to estrogen receptor (ER) α. Thus, in recent years, endocrine interventions that include estrogens have been discussed more and more critically, and their impact on different BC subgroups has increasingly gained interest. Carriers of pathogenic variants in BRCA1/2 genes are known to have a high risk of developing BC and ovarian cancer. However, there remain open questions to what extent endocrine interventions targeting ERα or the progesterone receptor further increase cancer risk in this subgroup. This review article aims to provide an overview and update on the effects of endocrine interventions on breast cancer risk in the general population in comparison to BRCA1/2 mutation carriers. Finally, future directions of research are addressed, to further improve the understanding of the effects of endocrine interventions on high-risk pathogenic variant carriers.

Breast cancer (BC) stands as a global concern, given its high incidence and impact on women\'s mortality. This complex disease has roots in various risk factors, some modifiable and others not. Understanding and identifying these factors can be instrumental in both preventing BC and improving survival rates. Remarkably, women\'s reproductive behaviors have emerged as critical determinants of BC susceptibility. Numerous studies have shed light on how aspects including age of menarche, first pregnancy and menopause along with number of pregnancies, hormone replacement therapies, can influence one\'s risk of developing BC. Furthermore, the act of breastfeeding and its duration have shown an inverse relationship with BC risk. This review delves into the biological and molecular mechanisms associated with breastfeeding that contribute to BC protection. It highlights the role of endocrine processes triggered by suckling stimulation, the gradual onset of lactational amenorrhea, delayed weaning, reduced lifetime menstrual cycles, chromosomal repair mechanisms, and immunological events throughout the lactation cycle. These insights provide a potential explanation for the protective effects conferred by breastfeeding against breast carcinomas.
Angesichts der hohen Inzidenz von Brustkrebs und deren Auswirkung auf die Mortalität von Frauen bleibt Brustkrebs (BK) ein globales Problem. Diese komplexe Erkrankung hat ihren Ursprung in verschiedenen Risikofaktoren, von denen einige veränderbar sind und andere nicht. Das Verständnis und die Identifikation dieser Faktoren kann entscheidend sein, sowohl bei der Prävention von BK als auch bei der Verbesserung der Überlebensraten. Bemerkenswerterweise hat sich herausgestellt, dass das Fortpflanzungsverhalten von Frauen einen kritischen Faktor für die Anfälligkeit für BK darstellt. Zahlreiche Studien haben Aufschluss darüber gegeben, wie bestimmte Aspekte wie Alter beim Eintritt der ersten Menstruationsblutung, Alter bei der ersten Schwangerschaft und Alter beim Eintritt der Wechseljahre sowie Anzahl von Schwangerschaften und Hormonersatztherapien das Brustkrebsrisiko beeinflussen können. Es hat sich auch herausgestellt, dass das Stillen und die Stilldauer eine umgekehrte Relation zum Brustkrebsrisiko haben. Dieser Übersichtsartikel untersucht die mit Stillen assoziierten biologischen und molekularen Mechanismen, die helfen können, BK vorzubeugen. Die Rolle von durch Säugen stimulierten endokrinen Prozessen, z. B. das allmähliche Einsetzen der laktationsbedingten Amenorrhö, das verzögerte Abstillen, die verminderte Anzahl von Menstruationszyklen im Laufe des Lebens, die chromosomalen Reparaturmechanismen und immunologischen Ereignisse während des Laktationszyklus, werden beschrieben. Diese Einsichten bieten eine mögliche Erklärung für den durch das Stillen bedingten Schutz gegen Brustkrebs.

Higher breast cancer mortality rates continue to disproportionally affect black women (BW) compared to white women (WW). This disparity is largely due to differences in tumor aggressiveness that can be related to distinct ancestry-associated breast tumor microenvironments (TMEs). Yet, characterization of the normal microenvironment (NME) in breast tissue and how they associate with breast cancer risk factors remains unknown. N-glycans, a glucose metabolism-linked post-translational modification, has not been characterized in normal breast tissue. We hypothesized that normal female breast tissue with distinct Breast Imaging and Reporting Data Systems (BI-RADS) categories have unique microenvironments based on N-glycan signatures that varies with genetic ancestries. Profiles of N-glycans were characterized in normal breast tissue from BW (n = 20) and WW (n = 20) at risk for breast cancer using matrix assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI). A total of 176 N-glycans (32 core-fucosylated and 144 noncore-fucosylated) were identified in the NME. We found that certain core-fucosylated, outer-arm fucosylated and high-mannose N-glycan structures had specific intensity patterns and histological distributions in the breast NME dependent on BI-RADS densities and ancestry. Normal breast tissue from BW, and not WW, with heterogeneously dense breast densities followed high-mannose patterns as seen in invasive ductal and lobular carcinomas. Lastly, lifestyles factors (e.g. age, menopausal status, Gail score, BMI, BI-RADS) differentially associated with fucosylated and high-mannose N-glycans based on ancestry. This study aims to decipher the molecular signatures in the breast NME from distinct ancestries towards improving the overall disparities in breast cancer burden.