HER2 phosphorylation induced by TGF-ß promotes mammary morphogenesis and breast cancer progression.

Transforming growth factor ß (TGF-ß) and HER2 signaling collaborate to promote breast cancer progression. However, their molecular interplay is largely unclear. TGF-ß can activate mitogen-activated protein kinase (MAPK) and AKT, but the underlying mechanism is not fully understood. In this study, we report that TGF-ß enhances HER2 activation, leading to the activation of MAPK and AKT. This process depends on the TGF-ß type I receptor TßRI kinase activity. TßRI phosphorylates HER2 at Ser779, promoting Y1248 phosphorylation and HER2 activation. Mice with HER2 S779A mutation display impaired mammary morphogenesis, reduced ductal elongation, and branching. Furthermore, wild-type HER2, but not S779A mutant, promotes TGF-ß-induced epithelial-mesenchymal transition, cell migration, and lung metastasis of breast cells. Increased HER2 S779 phosphorylation is observed in human breast cancers and positively correlated with the activation of HER2, MAPK, and AKT. Our findings demonstrate the crucial role of TGF-ß-induced S779 phosphorylation in HER2 activation, mammary gland development, and the pro-oncogenic function of TGF-ß in breast cancer progression.

The liver kinase B1 supports mammary epithelial morphogenesis by inhibiting critical factors that mediate epithelial-mesenchymal transition.

The liver kinase B1 (LKB1) controls cellular metabolism and cell polarity across species. We previously established a mechanism for negative regulation of transforming growth factor ß (TGFß) signaling by LKB1. The impact of this mechanism in the context of epithelial polarity and morphogenesis remains unknown. After demonstrating that human mammary tissue expresses robust LKB1 protein levels, whereas invasive breast cancer exhibits significantly reduced LKB1 levels, we focused on mammary morphogenesis studies in three dimensional (3D) acinar organoids. CRISPR/Cas9-introduced loss-of-function mutations of STK11 (LKB1) led to profound defects in the formation of 3D organoids, resulting in amorphous outgrowth and loss of rotation of young organoids embedded in matrigel. This defect was associated with an enhanced signaling by TGFß, including TGFß auto-induction and induction of transcription factors that mediate epithelial-mesenchymal transition (EMT). Protein marker analysis confirmed a more efficient EMT response to TGFß signaling in LKB1 knockout cells. Accordingly, chemical inhibition of the TGFß type I receptor kinase largely restored the morphogenetic defect of LKB1 knockout cells. Similarly, chemical inhibition of the bone morphogenetic protein pathway or the TANK-binding kinase 1, or genetic silencing of the EMT factor SNAI1, partially restored the LKB1 knockout defect. Thus, LKB1 sustains mammary epithelial morphogenesis by limiting pathways that promote EMT. The observed downregulation of LKB1 expression in breast cancer is therefore predicted to associate with enhanced EMT induced by SNAI1 and TGFß family members.

Correlation between imaging findings and hormonal markers at the onset of puberty in girls.

INTRODUCTION: This study aimed to determine the diagnostic performance of transabdominal pelvic ultrasonography and bone age in identifying the onset of puberty in girls at the Clínica Las Américas in Medellín, Colombia. METHODS: We included girls aged ≤11 years referred to our clinic between March 2016 and March 2019 for signs of puberty. We compared the findings on pelvic and breast ultrasonography and bone age versus the baseline measurement of luteinizing hormone (LH) in serum, used as the reference standard for identifying the onset of puberty. We calculated the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive and negative likelihood ratios, analyzing subgroups of patients of different ages. RESULTS: We analyzed 43 patients. Ultrasound assessment of breast development had the highest sensitivity (94.1%) of all the imaging parameters evaluated, but its specificity was low. However, characteristics such as the length of the body of the uterus >3.0 cm and the presence of endometrial echoes were highly specific for identifying the onset of puberty, particularly in patients aged ≤8 years. CONCLUSION: Pelvic ultrasonography, ultrasonographic assessment of Tanner stage of breast development, and the evaluation of bone age are useful tools for the imaging confirmation of the onset of puberty. The results of this study support the use of these techniques in clinical practice in the workup for pubertal disorders in girls.

Chemical Effects on Breast Development, Function, and Cancer Risk: Existing Knowledge and New Opportunities.

Population studies show worrisome trends towards earlier breast development, difficulty in breastfeeding, and increasing rates of breast cancer in young women. Multiple epidemiological studies have linked these outcomes with chemical exposures, and experimental studies have shown that many of these chemicals generate similar effects in rodents, often by disrupting hormonal regulation. These endocrine-disrupting chemicals (EDCs) can alter the progression of mammary gland (MG) development, impair the ability to nourish offspring via lactation, increase mammary tissue density, and increase the propensity to develop cancer. However, current toxicological approaches to measuring the effects of chemical exposures on the MG are often inadequate to detect these effects, impairing our ability to identify exposures harmful to the breast and limiting opportunities for prevention. This paper describes key adverse outcomes for the MG, including impaired lactation, altered pubertal development, altered morphology (such as increased mammographic density), and cancer. It also summarizes evidence from humans and rodent models for exposures associated with these effects. We also review current toxicological practices for evaluating MG effects, highlight limitations of current methods, summarize debates related to how effects are interpreted in risk assessment, and make recommendations to strengthen assessment approaches. Increasing the rigor of MG assessment would improve our ability to identify chemicals of concern, regulate those chemicals based on their effects, and prevent exposures and associated adverse health effects.

Determining the timing of pubertal onset via a multicohort analysis of growth.

OBJECTIVE: Growth-based determination of pubertal onset timing would be cheap and practical. We aimed to determine this timing based on pubertal growth markers. Secondary aims were to estimate the differences in growth between cohorts and identify the role of overweight in onset timing. DESIGN: This multicohort study includes data from three Finnish cohorts-the Type 1 Diabetes Prediction and Prevention (DIPP, N = 2,825) Study, the Special Turku Coronary Risk Factor Intervention Project (STRIP, N = 711), and the Boy cohort (N = 66). Children were monitored for growth and Tanner staging (except in DIPP). METHODS: The growth data were analyzed using a Super-Imposition by Translation And Rotation growth curve model, and pubertal onset analyses were run using a time-to-pubertal onset model. RESULTS: The time-to-pubertal onset model used age at peak height velocity (aPHV), peak height velocity (PHV), and overweight status as covariates, with interaction between aPHV and overweight status for girls, and succeeded in determining the onset timing. Cross-validation showed a good agreement (71.0% for girls, 77.0% for boys) between the observed and predicted onset timings. Children in STRIP were taller overall (girls: 1.7 [95% CI: 0.9, 2.5] cm, boys: 1.0 [0.3, 2.2] cm) and had higher PHV values (girls: 0.13 [0.02, 0.25] cm/year, boys: 0.35 [0.21, 0.49] cm/year) than those in DIPP. Boys in the Boy cohort were taller (2.3 [0.3, 4.2] cm) compared with DIPP. Overweight girls showed pubertal onset at 1.0 [0.7, 1.4] year earlier compared with other girls. In boys, there was no such difference. CONCLUSIONS: The novel modeling approach provides an opportunity to evaluate the Tanner breast/genital stage-based pubertal onset timing in cohort studies including longitudinal data on growth but lacking pubertal follow-up.

The concordance between ultrasonographic stage of breast and Tanner stage of breast for overweight and obese girls: a school population-based study.

OBJECTIVES: In this study, we evaluated the concordance between the ultrasonographic stage of breast (US B) and Tanner stage of breast (TS B) for overweight and obese girls based on a school population study. METHODS: We conducted multistage, stratified cluster, and random-proportional sampling and ultimately included 221 girls (aged 6-10 years). RESULTS: This study revealed that the concordance was poor (accuracy=0.19 (95% confidence interval: 0.14, 0.25)) between US B and TS B among the 221 participants. When our subjects were stratified by weight, we observed a weak association between US B and TS B in the thin/normal weight group (r=0.34, p=0.001) but not in the overweight (r=0.097, p=0.38) or obese groups (r=-0.19, p=0.206), and as the body mass index (BMI) z-score increased, the overestimation ratio of TS B increased. US B manifested a positive correlation with breast bud diameter (BD) (r=0.885, p<0.001), follicle-stimulating hormone (r=0.235, p=0.009), and luteinizing hormone (r=0.192, p=0.037), but this was not the case with TS B. CONCLUSIONS: As the BMI z-score increased, the correlation between the two methods declined, and the overestimation ratio of TS B increased. US B is an objective and quantitative method used to evaluate breast development, and whether BD might replace US B as a routine diagnostic method to evaluate breast development in clinical practice needs to be confirmed in larger-sample studies.

Microenvironmental control of cell fate decisions in mammary gland development and cancer.

Cell fate decisions are critical for adequate tissue development, maintenance and regeneration. In the mammary gland, epithelial cell fates are tightly controlled by the microenvironment. Here, we review how cell fate decisions are regulated by components of the microenvironment during mammary gland development and how pathological changes in the microenvironment can alter cell fates, leading to malignancy. Specifically, we describe the current understanding of how mammary cell fate is controlled and directed by three elements: the extracellular matrix, the immune microenvironment, and hormones-and how these elements can converge to create microenvironments that promote a fourth element: DNA damage.

Reduction Mammaplasty for Macromastia in Adolescents: A Systematic Review and Pooled Analysis.

BACKGROUND: Reduction mammaplasty for macromastia is one of the most common operations performed by plastic surgeons. There remains hesitancy in operating on adolescents, as there is ongoing debate about breast regrowth and potential impact on breastfeeding. The goal of this study was to analyze these concerns by reviewing the current literature. METHODS: A systematic review of MEDLINE, Scopus, and Google Scholar was conducted using the following terms: "breast reduction" or "mammaplasty" or "breast reconstruction" and "adolescent" or "youth" or "pediatric" or "child" or "teen." Primary outcomes were success of breastfeeding after the procedure and procedure-related complications. RESULTS: Twenty-three studies (87 percent retrospective), consisting of 2926 patients with preoperative cup sizes of C to KK (mean, DDD), met inclusion criteria. Mean age at the time of surgery ranged from 16 to 21 years, with the youngest patient being 12 years old. The overall complication rate was 27.3 percent (95 percent CI, 14.4 to 42.5 percent). Minor complications (22.8 percent; 95 percent CI, 10.2 to 38.5 percent) were more common than major (4.2 percent; 95 percent CI, 1.6 to 7.9 percent). Eighteen percent of patients (95 percent CI, 2.2 to 43.8 percent) reported regrowth of their breast tissue postoperatively, with 2.7 percent (95 percent CI, 0.9 to 5.5 percent) undergoing a second revision mammaplasty. Fifty-three percent of patients (95 percent CI, 36.0 to 69.3 percent) did not attempt breastfeeding. Of those who attempted, 55.1 percent (95 percent CI, 34.4 to 74.9 percent) were successful. CONCLUSIONS: Prospective data are lacking. Patient counseling should focus on encouraging a trial of breastfeeding, despite surgical history. One-fifth of adolescent patients may notice breast regrowth postoperatively; however, the amount of regrowth is likely small and unlikely to reexacerbate symptoms, as the rate of revision surgery is small.

Breast development in a 7 year old girl with CF treated with ivacaftor: An indication for personalized dosing?

Substantial progress has been made in the treatment of Cystic fibrosis due to introduction of CFTR modulators. However, little is known about the long term side effects of treatment with these drugs. We here present a 7 year old girl with CF who presented with breast development as a rare dose dependent side effect of treatment with ivacaftor and we report data on the correlation between drug plasma concentration and clinical effect, bodyweight, and BSA in 16 patients. Higher plasma concentrations did not correlate with clinical effect, as change in FEV1 and sweat chloride concentration. Patients with low bodyweight or BSA tended to have higher plasma concentrations. This might indicate that the current recommended dose of ivacaftor is at the top of the dose-response curve and that some patients can be treated with lower doses of ivacaftor with similar clinical effect.

Characterization of pubertal development of girls in rural Bangladesh.

This study aimed to describe the timing and patterns of pubertal maturation of girls living in rural Bangladesh. Starting in September 2015, a total of 15,320 girls from a birth cohort, aged 9 to 15 years at initial encounter, were visited twice at about a one year interval, typically in their birth month. Participants were asked to self-report extent of pubertal maturation, including breast development, pubic hair growth and age at menarche, if applicable. Pubertal stage (abbreviated as B2 and B3-4 for breast development and PH2 and PH3-4 for pubic hair growth) was assigned. Data from both visits were pooled, yielding a total of 29,377 age-related observations per pubertal characteristic. Probit regression models were used to estimate distributions of age at which each stage of pubertal development was attained. Before age 8, <3% of the study population initiated pubertal maturation as indicated by onset of breast development (B2). The median (95% confidence interval) age of B2 and B3-4 was 11.02 (11.00-11.04) and 12.82 (12.80-12.83) years, respectively; and 12.93 (12.91-12.94) and 14.29 (14.27-14.31) years for the onset (PH2) and advanced stage (PH3-4) of pubic hair growth, respectively. Median age at menarche was 13.17 (13.15-13.19) years, with 2.15 years of timespan from B2 to menarche. Girls in rural Bangladesh progressed through puberty following a well-documented sequence of sexual maturation stages. The age at which each pubertal milestone took place was somewhat later, but the tempo from breast development to menarche was comparable to that observed elsewhere. Our findings present a current norm of pubertal maturation in a typical, rural adolescent population in South Asia, which could help inform future studies and interventions to preserve or improve early adolescent health and development.

Differential substrate use in EGF- and oncogenic KRAS-stimulated human mammary epithelial cells.

Many metabolic phenotypes in cancer cells are also characteristic of proliferating nontransformed mammalian cells, and attempts to distinguish between phenotypes resulting from oncogenic perturbation from those associated with increased proliferation are limited. Here, we examined the extent to which metabolic changes corresponding to oncogenic KRAS expression differed from those corresponding to epidermal growth factor (EGF)-driven proliferation in human mammary epithelial cells (HMECs). Removal of EGF from culture medium reduced growth rates and glucose/glutamine consumption in control HMECs despite limited changes in respiration and fatty acid synthesis, while the relative contribution of branched-chain amino acids to the TCA cycle and lipogenesis increased in the near-quiescent conditions. Most metabolic phenotypes measured in HMECs expressing mutant KRAS were similar to those observed in EGF-stimulated control HMECs that were growing at comparable rates. However, glucose and glutamine consumption as well as lactate and glutamate production were lower in KRAS-expressing cells cultured in media without added EGF, and these changes correlated with reduced sensitivity to GLUT1 inhibitor and phenformin treatment. Our results demonstrate the strong dependence of metabolic behavior on growth rate and provide a model to distinguish the metabolic influences of oncogenic mutations and nononcogenic growth.

A rare case of primary amenorrhoea and breast development in a 46,XY 15-year-old girl.

A disorder of sex development (DSD) is defined as a congenital condition in which development of chromosomal, gonadal, or anatomical sex is atypical. Swyer syndrome is an example of 46,XY DSD with a female phenotype. It usually becomes apparent in adolescence with delayed puberty and amenorrhoea. Spontaneous breast development is very rare. A 15-year-old girl was presented due to primary amenorrhoea with breast development compatible with Tanner stage V. Hormonal tests revealed hypergonadotropic hypogonadism with low level of oestradiol. Pelvic ultrasound and magnetic resonance imaging revealed a small uterus, and no ovaries were found. In the right lower abdomen, a structure of unknown origin was visible. The chromosome analysis revealed a 46,XY karyotype. The patient was qualified for a laparoscopic bilateral gonadectomy. Postoperative histopathological examination revealed gonadoblastoma. We underline the need to consider DSD 46,XY in the presence of primary amenorrhoea, even when pubertal development is present. Germ cell tumors have a tendency to grow and metastasize rapidly. Delayed diagnosis may increase the risk of malignant transformation and cause a poor diagnosis.

Experience of Chest Dysphoria and Masculinizing Chest Surgery in Transmasculine Youth.

OBJECTIVES: Transmasculine individuals, those assigned female sex at birth but who identify as masculine, have high rates of suicidal behavior and often suffer from chest dysphoria (discomfort and distress from unwanted breast development). Growing numbers of transmasculine youth are pursuing definitive treatment with masculinizing chest surgery (MCS), and adult studies reveal marked benefits of MCS, although little is known about the impact of chest dysphoria on transmasculine youth or the optimal timing of MCS. In this study, we aimed to explore youth experiences of chest dysphoria and the impact of MCS. METHODS: Transmasculine youth aged 13 to 21 were recruited from a pediatric hospital-based gender clinic. Participants completed a semistructured qualitative interview exploring the experience of chest dysphoria and thoughts about or experiences with MCS. Interview transcripts were coded by 3 investigators employing modified grounded theory, with the median interrater reliability at κ = 0.92. RESULTS: Subjects (N = 30) were a mean age of 17.5 years, and 47% had undergone MCS. Youth reported that chest dysphoria triggered strong negative emotions and suicidal ideation, caused a myriad of functional limitations, and was inadequately relieved by testosterone therapy alone. All post-MCS youth reported near or total resolution of chest dysphoria, lack of regret, and improved quality of life and functioning. CONCLUSIONS: We observed consensus that chest dysphoria is a major source of distress and can be functionally disabling to transmasculine youth. MCS performed during adolescence, including before age 18, can alleviate suffering and improve functioning. Additional research is needed to develop patient-reported outcome measures to assess the impact of chest dysphoria and MCS.

A novel multi-study intervention investigating the short and long term effects of a posture bra on whole body and breast kinematics.

BACKGROUND: Poor standing posture has been reported in women with larger breasts, increasing the risk of back pain. Whilst breast reduction surgery can improve posture, conservative measures such as special bras may offer short or long-term relief of symptoms without surgical intervention. RESEARCH QUESTION: This study aimed to utilise a multi-study intervention to investigate the short and long-term kinematic effects of wearing a posture bra. METHODS: Study one utilised biomechanics and physiotherapy expertise to modify the design of a prototype bra to improve posture and breast kinematics; resulting in a second-generation posture bra. To test this bra, 24 females were randomly assigned to control and intervention groups. The control group wore their everyday bra; the intervention group wore the generation 2 posture bra in place of their everyday bra for three months. Pre and post intervention, posture (spine curvature, scapula position, whole body alignment) and breast kinematics were assessed during sitting, standing and walking. Short-term effects of the posture bra were compared to an everyday bra and no bra (study two), whilst the long-term effects were compared using the no bra condition (study three). RESULTS: Biomechanical intervention improved posture and breast kinematics in a prototype posture bra resulting in a second-generation prototype. Pre-intervention, the generation 2 posture bra significantly improved scapula retraction by 6° during both sitting and standing, but also increased deviation of whole body alignment compared to everyday bra and no bra conditions. During walking the posture bra reduced breast motion by 17 % compared to the everyday bra. Following the three-month wearer intervention, scapula depression significantly improved in the intervention group. SIGNIFICANCE: A biomechanically informed posture bra was able to effectively support the breasts and improve scapula position without compromising spinal curvature, reducing the risk of musculoskeletal pain associated with poor posture.

Sustained Breast Development and Breast Anthropometric Changes in 3 Years of Gender-Affirming Hormone Treatment.

CONTEXT: Breast development is important for most trans women. An important limitation of current breast development measurement methods is that these do not allow for 3D volume analyses. OBJECTIVES: To examine breast development and change in anthropometry during the first 3 years of gender-affirming hormone treatment using 3D imaging. Associations with clinical or laboratory parameters and satisfaction with the gained breast development were also studied. DESIGN: Prospective cohort study. SETTING: Specialized tertiary gender identity clinic in Amsterdam, the Netherlands. PARTICIPANTS: Participants were 69 adult trans women with a median age of 26 years (interquartile range, 21-38). INTERVENTIONS: Gender-affirming hormone treatment. MAIN OUTCOME MEASURES: Volumetric and anthropometric breast development and satisfaction. RESULTS: Breast volume increased by 72 cc (95% confidence interval [CI], 48-97) to 100 cc (standard deviation 48). This resulted in a cup-size

Prepubertal Internalizing Symptoms and Timing of Puberty Onset in Girls.

Stressful environments have been associated with earlier menarche. We hypothesized that anxiety, and possibly other internalizing symptoms, are also associated with earlier puberty in girls. The Lessons in Epidemiology and Genetics of Adult Cancer From Youth (LEGACY) Girls Study (2011-2016) included 1,040 girls aged 6-13 years at recruitment whose growth and development were assessed every 6 months. Prepubertal maternal reports of daughter's internalizing symptoms were available for breast onset (n = 447), pubic hair onset (n = 456), and menarche (n = 681). Using Cox proportional hazard regression, we estimated prospective hazard ratios and 95% confidence intervals for the relationship between 1 standard deviation of the percentiles of prepubertal anxiety, depression, and somatization symptoms and the timing of each pubertal outcome. Multivariable models included age, race/ethnicity, study center, maternal education, body mass index percentile, and family history of breast cancer. Additional models included maternal self-reported anxiety. A 1-standard deviation increase in maternally reported anxiety in girls at baseline was associated with earlier subsequent onset of breast (hazard ratio (HR) = 1.22, 95% confidence interval (CI): 1.09, 1.36) and pubic hair (HR = 1.15, 95% CI: 1.01, 1.30) development, but not menarche (HR = 0.94, 95% CI: 0.83, 1.07). The association of anxiety with earlier breast development persisted after adjustment for maternal anxiety. Increased anxiety in young girls may indicate risk for earlier pubertal onset.

Optimal Timing for Reduction Mammaplasty in Adolescents.

BACKGROUND: Reduction mammaplasty effectively alleviates symptoms and restores quality of life. However, operating on adolescents remains controversial, partly because of fear of potential postoperative breast growth. This cross-sectional study provides surgeons with a method to predict the optimal timing, or biological "sweet spot," for reduction mammaplasty to minimize the risk of breast regrowth in adolescents. METHODS: The authors reviewed the medical records of women aged 12 to 21 years who underwent reduction mammaplasty from 2007 to 2019. Collected data included symptomology, perioperative details, and postoperative outcomes. RESULTS: Four hundred eighty-one subjects were included in analyses and were, on average, 11.9 years old at first menses (menarche) and 17.9 years old at surgery. Six percent of subjects experienced postoperative breast growth. Breast size appears to stabilize considerably later in obese adolescents compared to healthy-weight and overweight patients, and breast growth in obese macromastia patients may not end until 9 years after menarche. Operating on obese women before this time point increased the likelihood of glandular breast regrowth by almost 120 percent (OR, 1.18; 95 percent CI, 1.11 to 1.26). Surgery performed less than 3 years after menarche, the commonly regarded end of puberty, increased the likelihood of glandular regrowth by over 700 percent in healthy-weight and overweight subjects (OR, 7.43; 95 percent CI, 1.37 to 40.41). CONCLUSIONS: Findings suggest that reduction mammaplasty age restrictions imposed by care providers and third-party payors may be arbitrary. Surgical readiness should be determined on an individual basis incorporating the patient's biological and psychological maturity, obesity status, potential for postoperative benefit, and risk tolerance for postoperative breast growth. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

Association between indicators of systemic inflammation biomarkers during puberty with breast density and onset of menarche.

BACKGROUND: Systemic inflammation may play a role in shaping breast composition, one of the strongest risk factors for breast cancer. Pubertal development presents a critical window of breast tissue susceptibility to exogenous and endogenous factors, including pro-inflammatory markers. However, little is known about the role of systemic inflammation on adolescent breast composition and pubertal development among girls. METHODS: We investigated associations between circulating levels of inflammatory markers (e.g., interleukin-6 (IL-6), tumor necrosis factor receptor 2 (TNFR2), and C-reactive protein (CRP)) at Tanner stages 2 and 4 and breast composition at Tanner stage 4 in a cohort of 397 adolescent girls in Santiago, Chile (Growth and Obesity Cohort Study, 2006-2018). Multivariable linear models were used to examine the association between breast composition and each inflammatory marker, stratifying by Tanner stage at inflammatory marker measurement. Accelerated failure time models were used to evaluate the association between inflammatory markers concentrations at each Tanner stage and time to menarche. RESULTS: In age-adjusted linear regression models, a doubling of TNFR2 at Tanner 2 was associated with a 26% (95% CI 7-48%) increase in total breast volume at Tanner 4 and a 22% (95% CI 10-32%) decrease of fibroglandular volume at Tanner 4. In multivariable models further adjusted for body fatness and other covariates, these associations were attenuated to the null. The time to menarche was 3% (95% CI 1-5%) shorter among those in the highest quartile of IL-6 at Tanner 2 relative to those in the lowest quartile in fully adjusted models. Compared to those in the lowest quartile of CRP at Tanner 4, those in the highest quartile experienced 2% (95% CI 0-3%) longer time to menarche in multivariable models. CONCLUSIONS: Systemic inflammation during puberty was not associated with breast volume or breast density at the conclusion of breast development among pubertal girls after adjusting for body fatness; however, these circulating inflammation biomarkers, specifically CRP and IL-6, may affect the timing of menarche onset.

Endocrine-disrupting chemicals and breastfeeding duration: a review.

PURPOSE OF REVIEW: The purpose of this review is to describe epidemiologic and toxicological literature investigating how endocrine-disrupting chemicals (EDCs) affect mammary gland development and function, thereby impacting lactation duration. RECENT FINDINGS: Perfluoroalkyl and polyfluoroalkyl substances appear to reduce breastfeeding duration through impaired mammary gland development, lactogenesis, and suppressed endocrine signaling. Halogenated aromatic hydrocarbons have differing associations with lactation duration, likely because of the variety of signaling pathways that they affect, pointing to the importance of complex mixtures in epidemiologic studies. Although epidemiologic literature suggests that pesticides and fungicides decrease or have no effect on lactation duration, toxicology literature suggests enhanced mammary gland development through estrogenic and/or antiandrogenic pathways. Toxicological studies suggest that phthalates may affect mammary gland development via estrogenic pathways but no association with lactation duration has been observed. Bisphenol A was associated with decreased duration of breastfeeding, likely through direct and indirect action on estrogenic pathways. SUMMARY: EDCs play a role in mammary gland development, function, and lactogenesis, which can affect breastfeeding duration. Further research should explore direct mechanisms of EDCs on lactation, the significance of toxicant mixtures, and transgenerational effects of EDCs on lactation.