Breast cancer risk by age at birth, time since birth and time intervals between births: exploring interaction effects

Predicting breast cancer risk and its association to biopsychosocial factors among Taiwanese women with a family history of breast cancer: an investigation based on the Gail model

BACKGROUND

First-degree relatives with breast cancer have a two-fold higher risk than women without a family history. The Gail model approach has been employed in numerous studies to investigate the risk of breast cancer among women in a variety of countries. Nevertheless, the studies investigating the correlation between the level of breast cancer risk and biopsychosocial factors among Taiwanese women with a family history of breast cancer (FHBC) are limited. By using the Gail model, we explored the breast cancer risk score and its relationship to biopsychosocial factors among Taiwanese women with FHBC.

METHODS

The present study was a cross-sectional study from secondary data of the Taiwan Biobank from 2008 to 2018. Self-reports were conducted to determine biopsychosocial factors. A total of 3,060 women aged 35-70 years with and without FHBC were considered eligible for enrollment. The Gail model, which utilizes six questions, was used to estimate individual five-year absolute breast cancer risk. Women with scores at least 1.66% and above were categorized as high risk. In addition, we performed bivariate and multivariate logistic regression analysis using SPSS version 27 to predict the associations between biopsychosocial factors and the risk of breast cancer based on the Gail model. All analyses were stratified by age.

RESULTS

Among the 3,060 Taiwanese women, there was a statistically significant difference in breast cancer risk score between the groups with and without FHBC (p = < 0.001), stratified by age, of which 574 in FHBC group (34.2%) were identified as having a high breast cancer risk based on the Gail model. Furthermore, six out of 15 biopsychosocial factors were significantly associated with breast cancer risk in women under 50 years of age, while seven factors showed significant associations in women aged 50 years and older. Logistic regression analysis identified five biopsychosocial factors as consistent and significant predictors of breast cancer risk in women aged 50 years and older, highlighting this group as particularly vulnerable.

CONCLUSIONS

This study concludes that the Gail model identifies Taiwanese women who have a higher estimated risk of breast cancer based on cross-sectional data. Various biopsychosocial factors are associated with higher risk estimates in this population particularly in older women. Professionals can assist women in recognizing risk factors beyond the inevitable risk by encouraging regular screenings, positive behavior, and health promotion.

Understanding Susceptibility to Breast Cancer: From Risk Factors to Prevention Strategies

Breast cancer is the most common malignancy among women globally, with incidence rates continuing to rise. A comprehensive understanding of its risk factors and the underlying biological mechanisms that drive tumor initiation is essential for developing effective prevention strategies. This review examines key non-modifiable risk factors, such as genetic predisposition, demographic characteristics, family history, mammographic density, and reproductive milestones, as well as modifiable risk factors like exogenous hormone exposure, obesity, diet, and physical inactivity. Importantly, reproductive history plays a dual role, providing long-term protection while temporarily increasing breast cancer risk shortly after pregnancy. Current chemoprevention strategies primarily depend on selective estrogen receptor modulators (SERMs), including tamoxifen and raloxifene, which have demonstrated efficacy in reducing the incidence of estrogen receptor-positive breast cancer but remain underutilized due to adverse effects. Emerging approaches such as aromatase inhibitors, RANKL inhibitors, progesterone antagonists, PI3K inhibitors, and immunoprevention strategies show promise for expanding preventive options. Understanding the interactions between risk factors, hormonal influences, and tumorigenesis is critical for optimizing breast cancer prevention and advancing safer, more targeted chemopreventive interventions.

Managing pregnancy-associated breast cancer: A practical approach

Pregnancy-Associated Breast Cancer (PABC) is a rare but complex condition that presents both professional and ethical challenges. Diagnosis is often delayed due to breast changes associated with pregnancy and puerperium, which can mask malignant findings. Management requires a multidisciplinary approach that carefully balances maternal and fetal risks. Chemotherapy is generally reserved for the second and third trimesters to avoid teratogenicity, with anthracyclines being the most well-studied and safest agents in this setting. Surgical decisions are influenced by factors such as cancer stage, gestational age, and the timing of potential radiation therapy. Notably, radiation therapy, endocrine therapy, and most targeted therapies are contraindicated during pregnancy due to potential harm to the fetus. Comprehensive care should include robust social and mental health support for the mother and her family to help navigate the physical and emotional challenges during this period.

Multidisciplinary Management of Pregnancy-Associated Breast Cancer

Breast cancer during pregnancy is uncommon; however, it is one of the most common malignancies affecting pregnant women. Pregnancy-associated breast cancer (PABC) is a complex entity characterized by unique risk factors, presentation, and pathology. Furthermore, although management generally aims to mirror that for nonpregnant patients, there are distinct aspects of oncologic care delivery specific to PABC. The focus is on optimizing maternal outcomes while maximizing maternal and fetal safety. A multidisciplinary approach is key, and the timing of various treatment modalities is critical. Postdelivery care and counseling are also imperative to address issues such as contraception, breastfeeding, and future fertility. In the present review, we discuss the current knowledge base and the diagnostic and treatment landscape for PABC, including recent literature and practice pattern updates.

Molecular characterization of pregnancy-associated breast cancer and insights on timing from GEICAM-EMBARCAM study

Pregnancy-associated breast cancer (PABC), diagnosed during or shortly after pregnancy, is a challenging entity with an aggressive biology and poor prognosis. This study analyzed the clinicopathological characteristics and gene expression profile of 33 PABC and 26 non-PABC patients using the nCounter BC360 Panel (NanoString). Notably, PABC showed a higher prevalence of basal-like tumors than non-PABC (48.48% vs 15.38%, p = 0.012) and displayed 73 differentially expressed genes (e.g., DEPDC1, CCNA2, PSAT1, CDKN3, and FAM83D), enriched in DNA repair and cell proliferation pathways. Through the PPI network, we also identified a cluster of cell-cycle regulation genes like MYC, FOXM1, or PTEN. Interestingly, differences emerged when comparing patients diagnosed during gestation (PABC-GS) and the postpartum period (PABC-PP), with PABC-PP showing increased expression of immune-related genes, including PD-1, and greater immune cell infiltration (Tregs, macrophages, neutrophils, B-cells). These findings suggest an enhanced proliferative capacity and impaired DNA repair in PABC, and underscore the role of immune infiltration in postpartum cases; providing insights into its aggressive nature and potential targets.

Breast cancer risk assessment based on a predictive model: evaluation of risk factors among Japanese women

BACKGROUND

Each breast cancer (BC) risk factor has different effects on different populations. However, there are no well-studied and validated BC risk prediction models for Japanese women. We developed accessible predictive models for Japanese women with optimal variables to evaluate risk factors for use by both medical institutions and women for primary BC prevention and to increase the BC screening rate. We evaluated the characteristics and distribution diversity of risk factors in this population.

METHODS

This retrospective case-control study of 2,494 Japanese women included data from an original, paper-based questionnaire. The logistic regression models included 18 variables from 6 risk factors based on menopausal status (PRE, premenopausal; PERI, perimenopausal; and POST, postmenopausal). Models were evaluated based on the Akaike Information Criterion, area under the receiver operating characteristic curve (AUC), and internal validation. Bootstrap methods for bias correction in discrimination and calibration and standard deviations were calculated by the modified case-control ratio.

RESULTS

We created and evaluated 432 candidate models for each group. Notably, BMI, parity, FHx, and smoking history were found to increase risk in all groups. Risk-reducing factors included breastfeeding duration in the PRE and PERI models and regular alcohol consumption in the PERI and POST models. Age reduced risk in the PERI model but increased risk in the POST model. Differences were observed between PRE and PERI versus POST with respect to variable selection in parity and FHx. Our models had moderate discriminatory accuracy. AUCs (confidence intervals) of the PRE, PERI, and POST models were 0.669 (0.625-0.715), 0.669 (0.632-0.702), and 0.659 (0.627-0.693), respectively. Bias-corrected AUCs (standard deviations) were 0.697 (0.041) for PRE, 0.684 (0.033) for PERI, and 0.674 (0.031) for POST, respectively. Our models were well-calibrated after bias correction.

CONCLUSION

Our widely available, simple, and cost-effective models with optimal variables could indicate the characteristics of certain genetic and environmental risk factors for BC in Japanese women.

Inflammatory signalling during the perinatal period: Implications for short- and long-term disease risk

During pregnancy and the postpartum, there are dynamic fluctuations in steroid and peptide hormone levels as well as inflammatory signalling. These changes are required for a healthy pregnancy and can persist well beyond the postpartum. Many of the same hormone and inflammatory signalling changes observed during the perinatal period also play a role in symptoms related to autoimmune disorders, psychiatric disorders, and perhaps neurodegenerative disease later in life. In this review, we outline hormonal and immunological shifts linked to pregnancy and the postpartum and discuss the possible role of these shifts in increasing psychiatric, neurodegenerative disease risk and autoimmune symptoms during and following pregnancy. Furthermore, we discuss how key variables such as the number of births (parity) and sex of the fetus can influence inflammatory signalling, and possibly future disease risk, but are not often studied. We conclude by discussing the importance of studying female experiences such as pregnancy and parenting on physiology and disease.

Rat Models of Breast Cancer

As the first mammal to be domesticated for research purposes, rats served as the primary animal model for various branches of biomedical research, including breast cancer studies, up until the late 1990s and early 2000s. During this time, genetic engineering of mice, but not rats, became routine, and mice gradually supplanted rats as the preferred rodent model. But recent advances in creating genetically engineered rat models, especially with the assistance of CRISPR/Cas9 technology, have rekindled the significance of rats as a critical model in exploring various facets of breast cancer research. This is particularly pronounced in the study of the formation and progression of the estrogen receptor-positive subtype, which remains challenging to model in mice. In this chapter, we embark on a historical journey through the evolution of rat models in biomedical research and provide an overview of the general and histological characteristics of rat mammary glands. Next, we critically review major rat models for breast cancer research, including those induced by carcinogens, hormones, radiation, germline transgenes, germline knockouts, and intraductal injection of retrovirus/lentivirus to deliver oncogenic drivers into mature mammary glands. We also discuss the advances in building rat models using somatic genome editing powered by CRISPR/Cas9. This chapter concludes with our forward-looking perspective on future applications of advanced rat models in critical areas of breast cancer research that have continued to challenge the mouse model community.

Potential Risk and Protective Factors in High- and Low-incidence Breast Cancer Populations in Northeast India: A Cross-sectional Study

OBJECTIVE

The case-control study aims to identify the potential risk and protective factors contributing to breast cancer risk in the high-incidence Aizawl population and the low-incidence Agartala population, using age-specific prevalence data of established reproductive factors and body mass index (BMI) among healthy women.

METHODS

A risk profile survey was conducted on asymptomatic women aged 30-64 in Aizawl and Agartala towns. Data was analysed using SPSS software. A descriptive statistical analysis characterised variable distribution, and bivariate inferential analyses of variable differences including birth cohort study across two states were conducted. Logistic regression determined odds ratios of mean values of reproductive factors and BMI.

RESULTS

The study reports that in Aizawl, a high prevalence of delayed marriages, late pregnancies, postmenopausal obesity and family history are potential risk factors for breast cancer in women, while an elevated mean age at menarche, high parity, and extended breastfeeding are protective factors. Conversely, in Agartala, early marriage, early first childbirth, high parity, prolonged breastfeeding, and healthy BMI are associated with low breast cancer risk in women. The study underscores the potential risk factors of early menarche and an extended reproductive period for women in Agartala.

CONCLUSION

The study emphasizes the importance of conducting age-specific prevalence studies in healthy women to identify critical risk and protective factors for breast cancer. Such information is crucial for healthcare professionals to develop prevention strategies, raise public awareness, and facilitate early detection of breast cancer in different populations. The study results will also set the stage for more extensive research on risk and protective factors for breast cancer in the Northeast region of India.

Roles of Mesenchymal Stem Cells in Breast Cancer Therapy: Engineered Stem Cells and Exosomal Cell-Free Based Therapy

Breast cancer has a high prevalence among women, with a high mortality rate. The number of people who suffer from breast cancer disease is increasing, whereas metastatic cancers are mostly incurable, and existing therapies have unfavorable side effects. For an extended duration, scientists have dedicated their efforts to exploring the potential of mesenchymal stem cells (MSCs) for the treatment of metastatic cancers, including breast cancer. MSCs could be genetically engineered to boost their anticancer potency. Furthermore, MSCs can transport oncolytic viruses, suicide genes, and anticancer medicines to tumors. Extracellular vesicles (EVs) are MSC products that have attracted scientist's attention as a cell-free treatment. This study narratively reviews the current state of knowledge on engineered MSCs and their EVs as promising treatments for breast cancer.

Epigenetic and Immune Mechanisms Linking Breastfeeding to Lower Breast Cancer Rates

This review shows how mammary stem cells (MaSCs) influence breast development, breastfeeding, and breast cancer risk. MaSCs, which can differentiate into various cell types, are vital for breast tissue health, but also disease development in breast tissue. Research shows that breastfeeding affects MaSCs, offering protection against breast cancer through various mechanisms. Hormonal changes such as increased prolactin concentration, oxytocin secretion, lower progesterone levels, and reduced exposure to estrogen during lactation promote apoptosis in potential cancer cells, boost immune surveillance, and modulate inflammation. Key findings reveal that pregnancy at an earlier age and extended breastfeeding reduce MaSC numbers, lowering cancer risk. Additionally, breastfeeding induces various epigenetic changes, such as DNA methylation and histone modification, which provide long-term protection against the development of cancer. Components of breast milk, like alpha-lactalbumin and lactoferrin, contribute by promoting cancer cell apoptosis and inhibiting tumor growth. The dual benefits of breastfeeding are reduced breast cancer risk for mothers and immunological advantages for infants. Multicenter epidemiology research has focused particular attention on longer breastfeeding duration associated with a reduced risk of triple-negative breast cancer. This review offers comprehensive evidence that breastfeeding protects against breast cancer through various biological, hormonal, and molecular mechanisms, showing the importance of promoting breastfeeding as a natural cancer prevention method. This article reviews the role of mammary stem cells in breast development, lactation, and breast cancer.

Breast cancer prognosis through the use of multi-modal classifiers: current state of the art and the way forward

We present a survey of the current state-of-the-art in breast cancer detection and prognosis. We analyze the evolution of Artificial Intelligence-based approaches from using just uni-modal information to multi-modality for detection and how such paradigm shift facilitates the efficacy of detection, consistent with clinical observations. We conclude that interpretable AI-based predictions and ability to handle class imbalance should be considered priority.

Comparison of Cranial Cruciate Ligament Rupture Incidence among Parous and Nulliparous Rottweiler Bitches: Evidence from a Lifetime Cohort Study Supporting a Paradigm of Pregnancy-Associated Protection against Subsequent Non-Reproductive Disease Outcomes

Emerging evidence in women supports the notion that pregnancy may reset disease resistance, thereby providing protection against subsequent adverse health outcomes, but this hypothesis has not been adequately explored in domestic dogs. Cranial cruciate ligament (CCL) rupture is a degenerative orthopedic disease that frequently affects pet dogs, and its risk has been associated with disruption of the reproductive hormone axis. Our research team is conducting a lifetime cohort study of purebred Rottweilers in North America that have lived 30% longer than breed-average. Detailed medical and reproductive histories of 33 nulliparous and 32 parous Rottweilers were generated from questionnaires and review of medical records. Interviews with owners of bitches in the nulliparous group served to limit selection bias, confirming that in no instance was the reason for nulliparity based upon the owner's suspicion that a bitch had a heightened risk for CCL rupture. The risk of CCL rupture associated with parity and other exposure variables was estimated using multivariate logistic regression. Overall, CCL rupture was diagnosed in 17 of 65 (26%) bitches. Median age at first litter and CCL rupture were 3.6 and 6.5 years, respectively. Compared to nulliparous, parous bitches had a significant 94% reduction in CCL rupture risk adjusted for duration of ovary exposure, overweight body condition, dietary pattern, habitual physical activity, and work/sport activity [ORadjusted (95% CI) = 0.06 (0.01-0.46); (p = 0.006)]. The observed parity-associated CCL rupture risk reduction remained robust in sensitivity analysis excluding six nulliparous bitches for which decision not to breed was based on diagnosis of hip or elbow dysplasia, conditions which may be genetically linked to CCL rupture [ORadjusted (95% CI) = 0.08 (0.01-0.58); (p = 0.01)]. This work sets the stage for replication studies in other canine populations that should begin to explore the mechanistic basis for parity-associated CCL rupture risk reduction and to pursue other non-reproductive health outcomes in bitches whose incidence or severity may be parity-sensitive.

Hormone receptor-positive early breast cancer in young women: A comprehensive review

The incidence of breast cancer in ≤ 40 yr-old women (YWBC) has been steadily increasing in recent decades. Although this group of patients represents less than 10 % of all newly diagnosed BC cases it encompasses a significant burden of disease. Usually underrepresented in clinical trials, YWBCs are also characterized by late diagnoses and poorly differentiated, aggressive-subtype disease, partly explaining its poor prognosis along with a high recurrence risk, and high mortality rates. On the other hand, YWBC treatment poses unique challenges such as preservation of fertility, and long-term toxicity and adverse events. Herein, we summarize the current evidence in hormone receptor-positive YWBC including specific risk factors, clinicopathologic and genomic features, and available evidence on response to chemotherapy and endocrine therapy. Overall, we advocate for a more comprehensive multidisciplinary healthcare model to improve the outcomes and the quality of life of this subset of younger patients.

Pregnancy, abortion, and birth control methods' complicity with breast cancer occurrence

Reproductive factors play significantly important roles in determining the breast cancer (BC) risk. The impact of pregnancy, abortion, and birth control methods on tumor development remains unclear. It has been found that early full-term pregnancies in young women can lower their lifetime risk of developing the type of cancer in question. However, having a first full-term pregnancy at an older age can increase this risk. The relationship between pregnancy and breast cancer (BC) is, however, much more complicated. Both induced and spontaneous abortions lead to sudden changes in hormonal balance, which could cause different effects on sensitive breast epithelial cells, making abortion a potential risk factor for breast cancer. The influence of hormonal contraception on carcinogenesis is not comprehensively understood, and therefore, more exhaustive analysis of existing data and further investigation is needed. This review explores how the mentioned reproductive factors affect the risk of breast cancer (BC), focusing on the molecular mechanisms that contribute to its complexity. By comprehending this intricate network of relationships, we can develop new strategies for predicting and treating the disease.

Risk Factors and Preventive Measures for Breast Cancer

Background: Breast cancer is the most common cancer in women in many countries. Breast cancer is a multifactorial disease. This study investigates the possible influencing factors and preventive measures for breast cancer. Methods: The data for this study were obtained from WHO databases. First, age standardization was performed, followed by a correlation analysis. Relationships between the mortality rates of breast cancer and the possible influencing factors were analyzed. The significant results from the correlation analysis were analyzed using a stepwise regression analysis. In order to find out whether the application of a uniform screening program can reduce breast cancer mortality, the countries were divided into groups according to the time of initiation of the screening program, and breast cancer mortality was compared. Results: The correlation analysis showed a significant relationship with breast cancer mortality for 15 of 30 potential influencing factors. A stepwise multivariate regression analysis was performed with these 15 factors, which revealed 13 relevant factors. Two factors were more relevant: the number of radiotherapy units per 100,000 inhabitants and the proportion of the population (over 50 years of age) with a social network. These were followed by the proportion of general practitioners and obstetricians, as well as healthcare expenses. Breast cancer mortality differed between the countries that introduced the screening program in the 1990s and those that did so in the 2020s. Conclusions: A country's healthcare system influences breast cancer mortality through prevention, diagnosis. and treatment. Regular screening, counseling for socially disadvantaged women, and prompt treatment are important factors. In the future, prevention measures should also aim to strengthen the social environment. The prescription of social activities should be used as preventive care.

Pregnancy-Related Factors and Breast Cancer Risk for Women Across a Range of Familial Risk

Importance

Few studies have investigated whether the associations between pregnancy-related factors and breast cancer (BC) risk differ by underlying BC susceptibility. Evidence regarding variation in BC risk is critical to understanding BC causes and for developing effective risk-based screening guidelines.

Objective

To examine the association between pregnancy-related factors and BC risk, including modification by a of BC where scores are based on age and BC family history.

Design, Setting, and Participants

This cohort study included participants from the prospective Family Study Cohort (ProF-SC), which includes the 6 sites of the Breast Cancer Family Registry (US, Canada, and Australia) and the Kathleen Cuningham Foundation Consortium (Australia). Analyses were performed in a cohort of women enrolled from 1992 to 2011 without any personal history of BC who were followed up through 2017 with a median (range) follow-up of 10 (1-23) years. Data were analyzed from March 1992 to March 2017.

Exposures

Parity, number of full-term pregnancies (FTP), age at first FTP, years since last FTP, and breastfeeding.

Main Outcomes and Measures

BC diagnoses were obtained through self-report or report by a first-degree relative and confirmed through pathology and data linkages. Cox proportional hazards regression models estimated hazard ratios (HR) and 95% CIs for each exposure, examining modification by PARS of BC. Differences were assessed by estrogen receptor (ER) subtype.

Results

The study included 17 274 women (mean [SD] age, 46.7 [15.1] years; 791 African American or Black participants [4.6%], 1399 Hispanic or Latinx participants [8.2%], and 13 790 White participants [80.7%]) with 943 prospectively ascertained BC cases. Compared with nulliparous women, BC risk was higher after a recent pregnancy for those women with higher PARS (last FTP 0-5 years HR for interaction, 1.53; 95% CI, 1.13-2.07; P for interaction < .001). Associations between other exposures were limited to ER-negative disease. ER-negative BC was positively associated with increasing PARS and increasing years since last FTP (P for interaction < .001) with higher risk for recent pregnancy vs nulliparous women (last FTP 0-5 years HR for interaction, 1.54; 95% CI, 1.03-2.31). ER-negative BC was positively associated with increasing PARS and being aged 20 years or older vs less than 20 years at first FTP (P for interaction = .002) and inversely associated with multiparity vs nulliparity (P for interaction = .01).

Conclusions and Relevance

In this cohort study of women with no prior BC diagnoses, associations between pregnancy-related factors and BC risk were modified by PARS, with greater associations observed for ER-negative BC.

Different Oncogenes and Reproductive Histories Shape the Progression of Distinct Premalignant Clones in Multistage Mouse Breast Cancer Models

A remote carcinogen exposure can predispose to breast cancer onset decades later, suggesting that carcinogen-induced mutations generate long-lived premalignant clones. How subsequent events influence the progression of specific premalignant clones remains poorly understood. Herein, multistage mouse models of mammary carcinogenesis were generated by combining chemical carcinogen exposure [using 7,12-dimethylbenzanthracene (DMBA)] with transgenes that enable inducible expression of one of two clinically relevant mammary oncogenes: c-MYC (MYC) or PIK3CAH1047R (PIK). In prior work, DMBA exposure generated mammary clones bearing signature HrasQ61L mutations, which only progressed to mammary cancer after inducible Wnt1 oncogene expression. Here, after an identical DMBA exposure, MYC versus PIK drove cancer progression from mammary clones bearing mutations in distinct Ras family paralogs. For example, MYC drove cancer progression from either Kras- or Nras-mutant clones, whereas PIK transformed Kras-mutant clones only. These Ras mutation patterns were maintained whether oncogenic transgenes were induced within days of DMBA exposure or months later. Completing a full-term pregnancy (parity) failed to protect against either MYC- or PIK-driven tumor progression. Instead, a postpartum increase in mammary tumor predisposition was observed in the context of PIK-driven progression. However, parity decreased the overall prevalence of tumors bearing Krasmut, and the magnitude of this decrease depended on both the number and timing of pregnancies. These multistage models may be useful for elucidating biological features of premalignant mammary neoplasia.

Exploring novel protein-based biomarkers for advancing breast cancer diagnosis: A review

This review provides a contemporary examination of the evolving landscape of breast cancer (BC) diagnosis, focusing on the pivotal role of novel protein-based biomarkers. The overview begins by elucidating the multifaceted nature of BC, exploring its prevalence, subtypes, and clinical complexities. A critical emphasis is placed on the transformative impact of proteomics, dissecting the proteome to unravel the molecular intricacies of BC. Navigating through various sources of samples crucial for biomarker investigations, the review underscores the significance of robust sample processing methods and their validation in ensuring reliable outcomes. The central theme of the review revolves around the identification and evaluation of novel protein-based biomarkers. Cutting-edge discoveries are summarised, shedding light on emerging biomarkers poised for clinical application. Nevertheless, the review candidly addresses the challenges inherent in biomarker discovery, including issues of standardisation, reproducibility, and the complex heterogeneity of BC. The future direction section envisions innovative strategies and technologies to overcome existing challenges. In conclusion, the review summarises the current state of BC biomarker research, offering insights into the intricacies of proteomic investigations. As precision medicine gains momentum, the integration of novel protein-based biomarkers emerges as a promising avenue for enhancing the accuracy and efficacy of BC diagnosis. This review serves as a compass for researchers and clinicians navigating the evolving landscape of BC biomarker discovery, guiding them toward transformative advancements in diagnostic precision and personalised patient care.

Dual role of pregnancy in breast cancer risk

Reproductive history is one of the strongest risk factors for breast cancer in women. Pregnancy can promote short-term breast cancer risk, but also reduce a woman's lifetime risk of breast cancer. Changes in hormone levels before and after pregnancy are one of the key factors in breast cancer risk. This article summarizes the changes in hormone levels before and after pregnancy, and the roles of hormones in mammary gland development and breast cancer progression. Other factors, such as changes in breast morphology and mammary gland differentiation, changes in the proportion of mammary stem cells (MaSCs), changes in the immune and inflammatory environment, and changes in lactation before and after pregnancy, also play key roles in the occurrence and development of breast cancer. This review discusses the dual effects and the potential mechanisms of pregnancy on breast cancer risk from the above aspects, which is helpful to understand the complexity of female breast cancer occurrence.

Status of breast cancer detection in young women and potential of liquid biopsy

Young onset breast cancer (YOBC) is an increasing demographic with unique biology, limited screening, and poor outcomes. Further, women with postpartum breast cancers (PPBCs), cancers occurring up to 10 years after childbirth, have worse outcomes than other young breast cancer patients matched for tumor stage and subtype. Early-stage detection of YOBC is critical for improving outcomes. However, most young women (under 45) do not meet current age guidelines for routine mammographic screening and are thus an underserved population. Other challenges to early detection in this population include reduced performance of standard of care mammography and reduced awareness. Women often face significant barriers in accessing health care during the postpartum period and disadvantaged communities face compounding barriers due to systemic health care inequities. Blood tests and liquid biopsies targeting early detection may provide an attractive option to help address these challenges. Test development in this area includes understanding of the unique biology involved in YOBC and in particular PPBCs that tend to be more aggressive and deadly. In this review, we will present the status of breast cancer screening and detection in young women, provide a summary of some unique biological features of YOBC, and discuss the potential for blood tests and liquid biopsy platforms to address current shortcomings in timely, equitable detection.

Breast cancer and the steadily increasing maternal age: are they colliding?

BACKGROUND

Pregnancy-related cancers are mostly breast cancers, and their incidence is likely to increase as a result of the modern trend of delaying childbearing. In particular, advanced maternal age increases breast cancer risk, and younger breast cancer patients are more likely to die and metastasize. This study compared a population with a high incidence of delayed childbearing with another population with a lower mean age at childbirth in order to determine whether breast cancer diagnosis and childbearing age overlap.

METHODS

We retrospectively analyzed multiple data sources. The Surveillance, Epidemiology, and End Results (SEER) program, the United States National Center for Health Statistics as part of the National Vital Statistics System, the United Nations Population Division, the GLOBOCAN Cancer Observatory, the CLIO-INFRA project database, the Human Fertility Database, and anonymized local data were used.

RESULTS

As women's age at delivery increased, the convergence between their age distribution at breast cancer diagnosis and childbearing increased. In addition, the overlap between the two age distributions increased by more than 200% as the average age at delivery increased from 27 to 35 years.

CONCLUSIONS

As women's average childbearing age has progressively risen, pregnancy and breast cancer age distributions have significantly overlapped. This finding emphasizes the need for increased awareness and educational efforts to inform women about the potential consequences of delayed childbearing. By providing comprehensive information and support, women can make more informed decisions about their reproductive health and cancer prevention strategies.

Clinical characteristics and prognosis of postpartum breast cancer

PURPOSE

Postpartum breast cancer (PPBC) is a not well-established subset of breast cancer, and only few studies address its poorer prognosis. However, previous studies show that PPBC is associated with worse outcome with higher rates of metastasis than in young women's breast cancer (YWBC). We aimed to analyze the clinical characteristics and prognosis of PPBC based on the diagnosis period of PPBC.

METHODS

We retrospectively reviewed 208,780 patients with breast cancer from the Korean Breast Cancer Society registry (KBCSR) database between January 2000 and December 2014. We included premenopausal women aged 20-50 years who underwent breast cancer surgery. The patients were classified by 5-year intervals according to the diagnosis period of breast cancer, from the first birth to the breast cancer diagnosis.

RESULTS

Compared with patients in the other groups, patients diagnosed within postpartum 5 years (PPBC < 5 years) group were younger, had a more advanced stage, had lower estrogen receptor (ER) and progesterone receptor (PR) expression, and had a higher human epidermal growth factor receptor 2 (HER2) positive rate. Further, PPBC < 5 years group had a worse survival rate than the nulliparous and other groups (5-year cumulative survival: PPBC < 5 years group, 89%; nulliparous group, 97.3%; 5 ≤ PPBC < 10 years group, 93%). In the multivariate analysis, the PPBC < 5 years group was associated with a worse survival rate (hazard ratio 1.55, 95% confidence interval [CI] 1.148-2.094, p 0.004) after adjustment for age at diagnosis, breast cancer stage, ER and HER2 status, Ki-67 level, and chemotherapy.

CONCLUSION

Our findings indicated that patients diagnosed with breast cancer within the first 5 years after delivery had aggressive characteristics and a poor survival rate. It is important to elucidate the pathophysiology of PPBC and establish novel therapeutic strategies to improve the survival rate.

The mutational landscape of the adult healthy parous and nulliparous human breast

The accumulation of somatic mutations in healthy human tissues has been extensively characterized, but the mutational landscape of the healthy breast is still poorly understood. Our analysis of whole-genome sequencing shows that in line with other healthy organs, the healthy breast during the reproduction years accumulates mutations with age, with the rate of accumulation in the epithelium of 15.24 ± 5 mutations/year. Both epithelial and stromal compartments contain mutations in breast-specific driver genes, indicative of subsequent positive selection. Parity- and age-associated differences are evident in the mammary epithelium, partly explaining the observed difference in breast cancer risk amongst women of different childbearing age. Parity is associated with an age-dependent increase in the clone size of mutated epithelial cells, suggesting that older first-time mothers have a higher probability of accumulating oncogenic events in the epithelium compared to younger mothers or nulliparous women. In conclusion, we describe the reference genome of the healthy female human breast during reproductive years and provide evidence of how parity affects the genomic landscape of the mammary gland.

DCIS and LCIS: Are the Risk Factors for Developing In Situ Breast Cancer Different?

Ductal carcinoma in situ (DCIS) is widely accepted as a precursor of invasive ductal carcinoma (IDC). Lobular carcinoma in situ (LCIS) is considered a risk factor for invasive lobular carcinoma (ILC), and it is unclear whether LCIS is also a precursor. Therefore, it would be expected that similar risk factors predispose to both DCIS and IDC, but not necessarily LCIS and ILC. This study examined associations with risk factors using data from 3075 DCIS cases, 338 LCIS cases, and 1584 controls aged 35-60, recruited from the UK-based GLACIER and ICICLE case-control studies between 2007 and 2012. Analysis showed that breastfeeding in parous women was protective against DCIS and LCIS, which is consistent with research on invasive breast cancer (IBC). Additionally, long-term use of HRT in post-menopausal women increased the risk of DCIS and LCIS, with a stronger association in LCIS, similar to the association with ILC. Contrary to findings with IBC, parity and the number of births were not protective against DCIS or LCIS, while oral contraceptives showed an unexpected protective effect. These findings suggest both similarities and differences in risk factors for DCIS and LCIS compared to IBC and that there may be justification for increased breast surveillance in post-menopausal women taking long-term HRT.

Exposome epidemiology for suspect environmental chemical exposures during pregnancy linked to subsequent breast cancer diagnosis

Breast cancer is now the most common cancer globally, accounting for 12% of all new annual cancer cases worldwide. Despite epidemiologic studies having established a number of risk factors, knowledge of chemical exposure risks is limited to a relatively small number of chemicals. In this exposome research study, we used non-targeted, high-resolution mass spectrometry of pregnancy cohort biospecimens in the Child Health and Development Studies to test for associations with breast cancer identified via the California Cancer Registry. Second and third trimester archival samples were analyzed from 182 women who subsequently developed breast cancer and 384 randomly selected women who did not develop breast cancer. Environmental chemicals were annotated with the Toxin and Toxin-Target Database for chemical signals that were higher in breast cancer cases and used with an exposome epidemiology analytic framework to identify suspect chemicals and associated metabolic networks. Network and pathway enrichment analyses showed consistent linkage in both second and third trimesters to inflammation pathways, including linoleate, arachidonic acid and prostaglandins, and identified new suspect environmental chemicals associated with breast cancer, i.e., an N-substituted piperidine insecticide and a common commercial product, 2,4-dinitrophenol, linked to variations in amino acid and nucleotide pathways in second trimester and benzo[a]carbazole and a benzoate derivative linked to glycan and amino sugar metabolism in third trimester. The results identify new suspect environmental chemical risk factors for breast cancer and provide an exposome epidemiology framework for discovery of suspect environmental chemicals and potential mechanistic associations with breast cancer.

Gestational Breast Cancer - a Review of Outcomes, Pathophysiology, and Model Systems

The onset of pregnancy marks the start of offspring development, and represents the key physiological event that induces re-organization and specialization of breast tissue. Such drastic tissue remodeling has also been linked to epithelial cell transformation and the establishment of breast cancer (BC). While patient outcomes for BC overall continue to improve across subtypes, prognosis remains dismal for patients with gestational breast cancer (GBC) and post-partum breast cancer (PPBC), as pregnancy and lactation pose additional complications and barriers to several gold standard clinical approaches. Moreover, delayed diagnosis and treatment, coupled with the aggressive time-scale in which GBC metastasizes, inevitably contributes to the higher incidence of disease recurrence and patient mortality. Therefore, there is an urgent and evident need to better understand the factors contributing to the establishment and spreading of BC during pregnancy. In this review, we provide a literature-based overview of the diagnostics and treatments available to patients with BC more broadly, and highlight the treatment deficit patients face due to gestational status. Further, we review the current understanding of the molecular and cellular mechanisms driving GBC, and discuss recent advances in model systems that may support the identification of targetable approaches to block BC development and dissemination during pregnancy. Our goal is to provide an updated perspective on GBC, and to inform critical areas needing further exploration to improve disease outcome.

Barriers to Using Breast Cancer Screening Methods Among Adult Females in Jeddah, Saudi Arabia: A Cross-Sectional Study

Introduction Breast cancer (BC) is one of the most common cancers worldwide and it considerably increases morbidity and mortality globally. Screening methods, such as self-examination, clinical examination, and mammography, can help in early detection and treatment, which will help in improving survival rates and reducing mortality. While regular screening of the breast is essential to detect the earliest stages of breast cancer, not all women adhere to regular breast screening. Methods A cross-sectional study was conducted in Jeddah, Saudi Arabia, between December 2021 to July 2022. using an online self-administered questionnaire. The total number of responses (n = 328), Data was analyzed using SPSS 25. Results In this study, out of the 328 respondents, 18.9% reported undergoing regular mammography, 14.3% reported having regular clinical breast examinations, and 38.1% reported practicing regular breast self-examinations.. In addition, the participants' most known warning signs of BC were a lump under their armpit (69.1%). the most perceived barrier to breast self-examination (BSE) was Doing a breast examination will make her worry about what is wrong with her breast (47%). whereas the most barrier to clinical breast examination (CBE) was embarrassment (45.9%). On the other hand, the main barriers that prevented women from having mammograms were embarrassment (36%) and pain (32.6%). Conclusion The most perceived barrier to BSE was women's concern, while embarrassment and painful procedures were significant barriers to performing mammography and CBE. Therefore, adult females in Jeddah need educational programs to improve their knowledge and increase public awareness of breast cancer screening for early detection.

Exposome Epidemiology for Suspect Environmental Chemical Exposures during Pregnancy Linked to Subsequent Breast Cancer Diagnosis

Breast cancer is now the most common cancer globally, accounting for 12% of all new annual cancer cases worldwide. Despite epidemiologic studies having established a number of risk factors, knowledge of chemical exposure risks is limited to a relatively small number of chemicals. In this exposome research study, we used non-targeted, high-resolution mass spectrometry (HRMS) of pregnancy cohort biospecimens in the Child Health and Development Studies (CHDS) to test for associations with breast cancer identified via the California Cancer Registry. Second (T2) and third (T3) trimester archival samples were analyzed from 182 women who subsequently developed breast cancer and 384 randomly selected women who did not develop breast cancer. Environmental chemicals were annotated with the Toxin and Toxin-Target Database (T3DB) for chemical signals that were higher in breast cancer cases and used with an exposome epidemiology analytic framework to identify suspect chemicals and associated metabolic networks. Network and pathway enrichment analyses showed consistent linkage in both T2 and T3 to inflammation pathways, including linoleate, arachidonic acid and prostaglandins, and identified new suspect environmental chemicals associated with breast cancer, i.e., an N-substituted piperidine insecticide and a common commercial product, 2,4-dinitrophenol (DNP), linked to variations in amino acid and nucleotide pathways in T2 and benzo[a]carbazole and a benzoate derivative linked to glycan and amino sugar metabolism in T3. The results identify new suspect environmental chemical risk factors for breast cancer and provide an exposome epidemiology framework for discovery of suspect environmental chemicals and potential mechanistic associations with breast cancer.

Pregnancy-associated breast cancer: does timing of presentation affect outcome?

PURPOSE

Pregnancy-associated breast cancer (PABC) comprises breast cancer diagnosed during the gestational period or within 12 months postpartum. While the incidence of PABC appears to be increasing, data regarding prognosis remain limited.

METHODS

Here we evaluate clinicopathologic features, treatments, and clinical outcomes among women with stage 0-III PABC diagnosed between 1992 and 2020. Comparisons were made between women who were diagnosed with PABC during gestation and those who were diagnosed within 12 months postpartum.

RESULTS

A total of 341 women were identified, with a median age of 36 years (range 25-46). The pregnancy group comprised 119 (35%) women, while 222 (65%) women made up the postpartum group. Clinicopathologic features were similar between groups, with most patients being parous and presenting with stage I and II disease. Treatment delays were uncommon, with a median time from histologic diagnosis to treatment of 4 weeks for both groups. Recurrence-free survival was similar between groups: 67% at 10 years for both. While 10-year overall survival appeared higher in the postpartum group (83% versus 78%, p = 0.02), only the presence of nodal metastases was associated with an increased risk of death (hazard ratio 5.61, 95% CI 2.20-14.3, p < 0.001), whereas timing of diagnosis and receptor profile did not reach statistical significance.

CONCLUSION

Clinicopathologic features of women with PABC are similar regardless of timing of diagnosis. While 10-year recurrence-free survival is similar between groups, 10-year overall survival is higher among women diagnosed postpartum; however, timing of diagnosis may not be the driving factor in determining survival outcomes.

What Is Known about Breast Cancer in Young Women?

Breast cancer (BC) is the second leading cause of cancer-related death in women under the age of 40 years worldwide. In addition, the incidence of breast cancer in young women (BCYW) has been rising. Young women are not the focus of screening programs and BC in younger women tends to be diagnosed in more advanced stages. Such patients have worse clinical outcomes and treatment complications compared to older patients. BCYW has been associated with distinct tumour biology that confers a worse prognosis, including poor tumour differentiation, increased Ki-67 expression, and more hormone-receptor negative tumours compared to women >50 years of age. Pathogenic variants in cancer predisposition genes such as BRCA1/2 are more common in early-onset BC compared to late-onset BC. Despite all these differences, BCYW remains poorly understood with a gap in research regarding the risk factors, diagnosis, prognosis, and treatment. Age-specific clinical characteristics or outcomes data for young women are lacking, and most of the standard treatments used in this subpopulation currently are derived from older patients. More age-specific clinical data and treatment options are required. In this review, we discuss the epidemiology, clinicopathologic characteristics, outcomes, treatments, and special considerations of breast cancer in young women. We also underline future directions and highlight areas that require more attention in future studies.

Breast Carcinogenesis during Pregnancy: Molecular Mechanisms, Maternal and Fetal Adverse Outcomes

Breast cancer is a common type of cancer diagnosed during pregnancy, with increasing incidence over the last years, as more women choose to delay childbearing. Compared to breast cancer in general population, pregnancy-associated breast cancer (PABC) is significantly different in its terms of epidemiology, diagnostic and therapeutic management, while it exhibits particularly aggressive behavior, deriving from its unique molecular and biological profile. Although not fully elucidated, the pathophysiological basis of PABC can be traced back to a combination of hormonal and immune changes during pregnancy, breast involution and altered gene expression. There is considerable controversy in the existing literature about the influence of PABC on pregnancy outcomes, regarding both short- and long-term effects on maternal and fetal/neonatal health. The majority of PABC patients have advanced-stage disease at initial diagnosis and face a significantly poorer prognosis, with decreased survival rates. The most commonly reported adverse obstetrical–fetal events are preterm delivery and prematurity-associated neonatal morbidity, while other neonatal treatment-associated complications might also occur, even when safe therapeutic options are applied during pregnancy. The objective of the present comprehensive review was to summarize current knowledge and up-to-date evidence about the pathophysiological, molecular and biological basis of PABC, as well as its association with adverse maternal, obstetrical, fetal and neonatal outcomes.

Breastfeeding reduces the risk of breast cancer: A call for action in high-income countries with low rates of breastfeeding

Women in the UK have a 15% lifetime risk of developing breast cancer. Like other high-income countries, women in the UK are having children later in life which increases their risk. The risk of breast cancer is reduced by 4.3% for every 12 months of breastfeeding, this is in addition to the 7.0% decrease in risk observed for each birth. Breastfeeding reduces the risk of Triple-Negative Breast Cancer (20%) and in carriers of BRCA1 mutations (22-55%). The mechanisms of reduced risk as a result of pregnancy are related to changes in RNA processing and cellular differentiation. The UK has a low rate of breastfeeding (81%) and this is contrasted to countries with higher (Sweden, Australia) and lower rates (Ireland). The low UK rate is in part due to a lack of experience in the population, todays grandmothers have less experience with breastfeeding (62%) than their daughters. An estimated 4.7% of breast cancer cases in the UK are caused by not breastfeeding. The UK only has 43% of maternity services with full Baby-Friendly accreditation which promotes compliance with the WHO 'Ten Steps to Successful Breast Feeding'. Legislation in the UK and Europe is far short of the WHO Guidance on restricting the advertising of formula milk. Expansion of the Baby-Friendly Hospital Initiative, stricter laws on the advertising of formula milk and legislation to support nursing mothers in the workplace have the potential to increase breastfeeding in the UK. Women with a family history of breast cancer should particularly be supported to breastfeed as a way of reducing their risk.

Cancer Is Associated with the Emergence of Placenta-Reactive Autoantibodies

Placenta-specific antigens are minimally expressed or unexpressed in normal adult tissues, while they are widely expressed in cancer. In the course of carcinogenesis, a vast array of autoantibodies (AAbs) is produced. Here, we used a quantitative approach to determine the reactivity of AAbs in the sera of patients with breast (BrC: N = 100, 100% female, median age: 51 years), gastric (GC: N = 30, 46.6% female, median age: 57 years), bladder (BC: N = 29, 34.4% female, median age: 57 years), and colorectal (CRC: N = 34, 41.1% female, median age: 51 years) cancers against first-trimester (FTP) and full-term placental proteome (TP) in comparison with age- and sex-matched non-cancer individuals. Human-on-human immunohistochemistry was used to determine reactive target cells in FTP. The effect of pregnancy on the emergence of placenta-reactive autoantibodies was tested using sera from pregnant women at different trimesters of pregnancy. Except for BC, patients with BrC (p < 0.0284), GC (p < 0.0002), and CRC (p < 0.0007) had significantly higher levels of placenta-reactive AAbs. BrC (p < 0.0001) and BC (p < 0.0409) in the early stages triggered higher autoantibody reactivity against FTP. The reactivities of BrC sera with FTP did not show an association with ER, PR, or HER2 expression. Pregnancy in the third trimester was associated with the induction of TP- and not FTP-reactive autoantibodies (=0.018). The reactivity of BrC sera with placental proteins was found to be independent of gravidity or abortion. BrC sera showed a very strong and specific pattern of reactivity with scattered cells beneath the syncytiotrophoblast layer. Our results reinforce the concept of the coevolution of placentation and cancer and shed light on the future clinical application of the placental proteome for the non-invasive early detection and treatment of cancer.

Life-course fertility and multimorbidity among middle-aged and elderly women in China: Evidence from China health and retirement longitudinal study

Background

Multimorbidity has become an important public health problem in China, especially among middle-aged and elderly women. Few studies have been reported on the association between multimorbidity and female fertility, which is an important stage in the life course. This study aimed to explore the association between multimorbidity and fertility history among middle-aged and elderly women in China.

Methods

Data from 10,182 middle-aged and elderly female participants in the China Health and Retirement Longitudinal Study (CHARLS) in 2018 were used in this study. Multimorbidity was defined as the presence of at least two or more chronic conditions. Logistic regression analysis, negative binomial regression analysis, and restrictive cubic splines (RCSs) were used to analyze the relationship between female fertility history and multimorbidity or the number of chronic conditions. Multivariable linear regression was used to analyze the relationship between female fertility history and multimorbidity pattern factor scores.

Results

The results of this study showed that high parity and early childbearing were significantly associated with an increased risk of multimorbidity and an increased number of chronic conditions among middle-aged and elderly women in China. Late childbearing was significantly associated with reduced risk of multimorbidity and lessened diseases. Parity and age of first childbirth were significantly correlated with the odds of multimorbidity. The association between fertility history and multimorbidity was found to be influenced by age and urban-rural dual structure. Women with high parity tend to have higher factor scores of cardiac-metabolic, visceral-arthritic, and respiratory-psychiatric patterns. Women with early childbearing tended to have higher factor scores of the visceral-arthritic pattern and those with late childbearing tended to have lower factor scores of the cardiac-metabolic pattern.

Conclusion

Fertility history has a significant effect on multimorbidity in the middle and later lives of Chinese women. This study is of great importance for reducing the prevalence of multimorbidity among Chinese women through their life course and promoting health during their middle and later lives.

Distinct Reproductive Risk Profiles for Intrinsic-Like Breast Cancer Subtypes: Pooled Analysis of Population-Based Studies

BACKGROUND

Reproductive factors have been shown to be differentially associated with risk of estrogen receptor (ER)-positive and ER-negative breast cancer. However, their associations with intrinsic-like subtypes are less clear.

METHODS

Analyses included up to 23 353 cases and 71 072 controls pooled from 31 population-based case-control or cohort studies in the Breast Cancer Association Consortium across 16 countries on 4 continents. Polytomous logistic regression was used to estimate the association between reproductive factors and risk of breast cancer by intrinsic-like subtypes (luminal A-like, luminal B-like, luminal B-HER2-like, HER2-enriched-like, and triple-negative breast cancer) and by invasiveness. All statistical tests were 2-sided.

RESULTS

Compared with nulliparous women, parous women had a lower risk of luminal A-like, luminal B-like, luminal B-HER2-like, and HER2-enriched-like disease. This association was apparent only after approximately 10 years since last birth and became stronger with increasing time (odds ratio [OR] = 0.59, 95% confidence interval [CI] = 0.49 to 0.71; and OR = 0.36, 95% CI = 0.28 to 0.46 for multiparous women with luminal A-like tumors 20 to less than 25 years after last birth and 45 to less than 50 years after last birth, respectively). In contrast, parous women had a higher risk of triple-negative breast cancer right after their last birth (for multiparous women: OR = 3.12, 95% CI = 2.02 to 4.83) that was attenuated with time but persisted for decades (OR = 1.03, 95% CI = 0.79 to 1.34, for multiparous women 25 to less than 30 years after last birth). Older age at first birth (Pheterogeneity < .001 for triple-negative compared with luminal A-like breast cancer) and breastfeeding (Pheterogeneity < .001 for triple-negative compared with luminal A-like breast cancer) were associated with lower risk of triple-negative breast cancer but not with other disease subtypes. Younger age at menarche was associated with higher risk of all subtypes; older age at menopause was associated with higher risk of luminal A-like but not triple-negative breast cancer. Associations for in situ tumors were similar to luminal A-like.

CONCLUSIONS

This large and comprehensive study demonstrates a distinct reproductive risk factor profile for triple-negative breast cancer compared with other subtypes, with implications for the understanding of disease etiology and risk prediction.

Reproductive risk factors associated with breast cancer in young women by molecular subtype

BACKGROUND

Few studies have examined detailed features of pregnancy and the postpartum period as potential risk factors for early onset breast cancer (BC) by molecular subtype. These data may have value for improving risk assessment and prevention.

METHODS

We surveyed parous enrollees in the prospective Mayo Clinic Breast Disease Registry (MCBDR) who had been diagnosed with BC at age <55 years between 2015 and 2020. Summary statistics were used to describe survey responses and reproductive risk factors by BC subtype (defined by estrogen/progesterone receptors and human epidermal growth factor receptor expression, nurse-abstracted from the medical record). Associations were assessed with Kruskal-Wallis and Chi-Square tests, followed by age-adjusted linear and logistic regression models. We compared results from this parous cohort to those from a separate cohort of nulliparous MCBDR participants with BC diagnosed at age <55 years.

RESULTS

In 436 parous respondents with subtype data abstracted, we identified a higher frequency of BRCA1 mutation, earlier age at diagnosis, and lower BI in patients with triple negative BC. Comparing parous to nulliparous young women with breast cancer, the proportion with TNBC was larger in the latter (12.2% vs. 15.1%, p = 0.03).

CONCLUSIONS

Early age at diagnosis and deleterious BRCA1 mutation were more frequent among TNBC patients. In addition, parous young women with TNBC had a lower BI than those with other BC subtypes, a hypothesis-generating finding that supports the need for additional research on the cycle of pregnancy-lactation-postpartum involution and BC etiology.

Association between Obesity, Race or Ethnicity, and Luminal Subtypes of Breast Cancer

Luminal breast cancers are the most common genomic subtype of breast cancers where Luminal A cancers have a better prognosis than Luminal B. Exposure to sex steroids and inflammatory status due to obesity are key contributors of Luminal tumor development. In this study, 1928 patients with Luminal A breast cancer and 1610 patients with Luminal B breast cancer were compared based on body mass index (BMI), age, race, menopausal status, and expressed receptors (i.e., estrogen (ER), progesterone (PR), and human epidermal growth factor receptor 2 (HER2)). Patients with Luminal B tumors had a significantly higher mean BMI (Δ = 0.69 kgm−2 [0.17, 1.21], p = 0.010) versus Luminal A. Interestingly, the risks of Luminal B tumors were higher among Black/African American patients versus White and Hispanic patients (p < 0.001 and p = 0.001, respectively). When controlled for each other, Black/African American race (p < 0.001) and increased BMI (p = 0.008) were associated with increased risks of Luminal B carcinoma, while postmenopausal status was associated with a decreased risk (p = 0.028). Increased BMI partially mediated the strong association between Black/African American race and the risk of Luminal B carcinoma. Thus, Black/African American race along with obesity seem to be associated with an increased risk of more aggressive Luminal B breast carcinomas.

Modelling multiple time-scales with flexible parametric survival models

BACKGROUND

There are situations when we need to model multiple time-scales in survival analysis. A usual approach in this setting would involve fitting Cox or Poisson models to a time-split dataset. However, this leads to large datasets and can be computationally intensive when model fitting, especially if interest lies in displaying how the estimated hazard rate or survival change along multiple time-scales continuously.

METHODS

We propose to use flexible parametric survival models on the log hazard scale as an alternative method when modelling data with multiple time-scales. By choosing one of the time-scales as reference, and rewriting other time-scales as a function of this reference time-scale, users can avoid time-splitting of the data.

RESULT

Through case-studies we demonstrate the usefulness of this method and provide examples of graphical representations of estimated hazard rates and survival proportions. The model gives nearly identical results to using a Poisson model, without requiring time-splitting.

CONCLUSION

Flexible parametric survival models are a powerful tool for modelling multiple time-scales. This method does not require splitting the data into small time-intervals, and therefore saves time, helps avoid technological limitations and reduces room for error.

Gestational Hypertensive Disorders and Maternal Breast Cancer Risk in a Nationwide Cohort of 40,720 Parous Women

BACKGROUND

Preeclampsia and gestational hypertension are hypothesized to be associated with reduced maternal breast cancer risk, but the epidemiologic evidence is inconclusive. Our objective was to examine associations between gestational hypertensive disorders and breast cancer in a nationwide cohort of women with a family history of breast cancer.

METHODS

Women ages 35-74 years who had a sister previously diagnosed with breast cancer, but had never had breast cancer themselves, were enrolled in the Sister Study from 2003 to 2009 (N = 50,884). At enrollment, participants reported diagnoses of eclampsia, preeclampsia, or gestational hypertension in each pregnancy. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between history of a gestational hypertensive disorder and incident invasive breast cancer or ductal carcinoma in situ among 40,720 parous women. We used age as the time scale and adjusted for birth cohort, race-ethnicity, and reproductive, socioeconomic, and behavioral factors. We examined effect measure modification by risk factors for gestational hypertensive disease and breast cancer and assessed possible etiologic heterogeneity across tumor characteristics.

RESULTS

The prevalence of gestational hypertensive disease was 12%. During follow-up (mean = 10.9 years), 3,198 eligible women self-reported a breast cancer diagnosis. History of a gestational hypertensive disorder was not associated with breast cancer risk (HR = 1.0; 95% CI = 0.90, 1.1). We did not observe clear evidence of effect measure modification or etiologic heterogeneity.

CONCLUSIONS

History of a gestational hypertensive disorder was not associated with breast cancer risk in a cohort of women with a first-degree family history of breast cancer.

A tumor-suppressive function for Notch3 in the parous mammary gland

Notch3 promotes mammary luminal cell specification and forced Notch3 activation can induce mammary tumor formation. However, recent studies suggest a tumor-suppressive role for Notch3. Here, we report on Notch3 expression and functional analysis in the mouse mammary gland. Notch3 is expressed in the luminal compartment throughout mammary gland development, but switches to basal cells with initiation of post-lactational involution. Deletion of Notch3 caused a decrease of Notch activation in luminal cells and diminished luminal progenitors at puberty, as well as reduced alveolar progenitors during pregnancy. Parous Notch3−/− mammary glands developed hyperplasia with accumulation of CD24hiCD49flo cells, some of which progressed to invasive tumors with luminal features. Notch3 deletion abolished Notch activation in basal cells during involution, accompanied by altered apoptosis and reduced brown adipocytes, leading to expansion of parity-identified mammary epithelial cells (PI-MECs). Interestingly, the postpartum microenvironment is required for the stem cell activity of Notch3−/− PI-MECs. Finally, high expression of NOTCH3 is associated with prolonged survival in patients with luminal breast cancer. These results highlight an unexpected tumor-suppressive function for Notch3 in the parous mammary gland through restriction of PI-MEC expansion.

Reproductive history differs by molecular subtypes of breast cancer among women aged ≤ 50 years in Scotland diagnosed 2009–2016: a cross-sectional study

Background

The aetiology of breast cancers diagnosed ≤ 50 years of age remains unclear. We aimed to compare reproductive risk factors between molecular subtypes of breast cancer, thereby suggesting possible aetiologic clues, using routinely collected cancer registry and maternity data in Scotland.

Methods

We conducted a cross-sectional study of 4108 women aged ≤ 50 years with primary breast cancer diagnosed between 2009 and 2016 linked to maternity data. Molecular subtypes of breast cancer were defined using immunohistochemistry (IHC) tumour markers, oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER2), and tumour grade. Age-adjusted polytomous logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association of number of births, age at first birth and time since last birth with IHC-defined breast cancer subtypes. Luminal A-like was the reference compared to luminal B-like (HER2−), luminal B-like (HER2+), HER2-overexpressed and triple-negative breast cancer (TNBC).

Results

Mean (SD) for number of births, age at first birth and time since last birth was 1.4 (1.2) births, 27.2 (6.1) years and 11.0 (6.8) years, respectively. Luminal A-like was the most common subtype (40%), while HER2-overexpressed and TNBC represented 5% and 15% of cases, respectively. Larger numbers of births were recorded among women with HER2-overexpressed and TNBC compared with luminal A-like tumours (> 3 vs 0 births, OR 1.87, 95%CI 1.18–2.96; OR 1.44, 95%CI 1.07–1.94, respectively). Women with their most recent birth > 10 years compared to < 2 years were less likely to have TNBC tumours compared to luminal A-like (OR 0.63, 95%CI 0.41–0.97). We found limited evidence for differences by subtype with age at first birth.

Conclusion

Number of births and time since last birth differed by molecular subtypes of breast cancer among women aged ≤ 50 years. Analyses using linked routine electronic medical records by molecularly defined tumour pathology data can be used to investigate the aetiology and prognosis of cancer.

The relationship between tobacco and breast cancer incidence: A systematic review and meta-analysis of observational studies

Background

The effect of tobacco on breast cancer (BC) is controversial. The purpose of this study was to investigate the relationship between tobacco and BC.

Methods

A search was conducted in PubMed, EBSCO, Web of Science and Cochrane Library databases before February 2022. The adjusted odd ratio (OR) and corresponding 95% confidence interval (CI) were used to examine the relationship between active or passive smoking and BC risk.

Results

A total of 77 articles composed of 2,326,987 participants were included for this meta-analysis. Active (OR=1.15, 95% CI=1.11-1.20, p&lt;0.001) and passive (OR=1.17, 95% CI=1.09-1.24, p&lt;0.001) smoking increased the risk of BC in the female population, especially premenopausal BC (active smoking: OR=1.24, p&lt;0.001; passive smoking: OR=1.29, p&lt;0.001), but had no effect on postmenopausal BC (active smoking: OR=1.03, p=0.314; passive smoking: OR=1.13, p=0.218). Active smoking increased the risk of estrogen receptor-positive (ER+) BC risk (OR=1.13, p&lt;0.001), but had no effect on estrogen receptor-negative (ER-) BC (OR=1.08, p=0.155). The risk of BC was positively associated with the duration and intensity of smoking, negatively associated with the duration of smoking cessation. Active smoking increased the risk of BC in the multiparous population (OR=1.13, p&lt;0.001), but had no effect on the nulliparous population (OR=1.05, p=0.432), and smoking before the first birth (OR=1.22, 95% CI=1.17-1.27) had a greater impact on the risk of BC than smoking after the first birth (OR=1.08, 95% CI=1.04-1.12).

Conclusion

Smoking (active and passive) increased the risk of BC in women. The effect of smoking on BC was influenced by smoking-related factors (duration, intensity, years of quitting), population-related factors (fertility status), and BC subtypes.

Systematic Review Registration

identifier CRD42022322699.

Early life adversity, reproductive history and breast cancer risk

Background and objectives

Individuals who experience early life adversity are at an increased risk for chronic disease later in life. Less is known about how early life factors are associated with cancer susceptibility. Here, we use a life history framework to test whether early life adversity increases the risk of breast cancer. We predict that early life adversity can shift investment in somatic maintenance and accelerate the timing of reproduction, which may mediate or interact with the risk of breast cancer.

Methodology

We use population-wide data from the Utah Population Database (UPDB) and Utah Cancer Registry, leading to 24 957 cases of women diagnosed with breast cancer spanning 20 years (1990-2010) and 124 785 age-matched controls. We generated a cumulative early life adversity summation score to evaluate the interaction (moderation) and mediation between early life adversity, reproductive history and their association with breast cancer risk.

Results

Our analyses led to three key findings: (i) more early life adversity, when considered as a main effect, accelerates the time to first birth and death, (ii) early age at first birth and high parity decreases the risk of breast cancer and (iii) we find no association between early adversity and breast cancer risk either as a main effect or in its interaction with reproductive history.

Conclusion and implications

Early adversity elevates the risk of overall mortality through mechanisms other than breast cancer risk. This suggests early life factors can generate different effects on health. Future work should incorporate more complex view of life history patterns, including multiple life stages, when making predictions about cancer susceptibility.

Toward a digital analysis of environmental impacts on rodent mammary gland density during critical developmental windows

While mammographic breast density is associated with breast cancer risk in humans, there is no comparable surrogate risk measure in mouse and rat mammary glands following various environmental exposures. In the current study, mammary glands from mice and rats subjected to reproductive factors and exposures to environmental chemicals that have been shown to influence mammary gland development and/or susceptibility to mammary tumors were evaluated for histologic density by manual and automated digital methods. Digital histological density detected changes due to hormonal stimuli/reproductive factors (parity), dietary fat, and exposure to environmental chemicals, such as benzophenone-3 and a combination of perfluorooctanoic acid and zeranol. Thus, digital analysis of mammary gland density offers a high throughput method that can provide a highly reproducible means of comparing a measure of histological density across independent experiments, experimental systems, and laboratories. This methodology holds promise for the detection of environmental impacts on mammary gland structure in mice and rats that may be comparable to human breast density, thus potentially allowing comparisons between rodent models and human breast cancer studies.

The association between reproductive history and the multidimensional health of older adults in rural China and its gender differences: Evidence from the Chinese longitudinal healthy longevity survey

Background

Few studies have examined the association between reproductive history and the multidimensional health of older adults with more diverse reproductive histories and poorer health status in rural China. The purpose of this study is to explore the effect of parity, sex ratio of children and late childbearing on multidimensional health and its gender differences.

Methods

The analytical sample consisted of 3,377 older adults in rural China who participated in the Chinese Longitudinal Healthy Longevity Survey (CLHLS) in 2018. Linear regression models were applied to estimate the relationship between reproductive history and multidimensional health, with separate models for each indicator of health outcomes.

Results

Older adults in rural areas with greater parity were more likely to have better cognitive function (β = 0.409, 95% CI: 0.255–0.563), fewer Activities of Daily Living (ADL) limitations (β = −0.085, 95% CI: −0.137 to −0.034) and symptoms of depression (β = −0.396, 95% CI: −0.577 to −0.216). The social mechanism of intergenerational support from children later in life partly explained the positive effect of parity. Late childbearing had negative effects on cognitive function (β = −1.220, 95% CI: −1.895 to −0.545), ADL (β = 0.253, 95% CI: 0.028–0.478) and symptoms of depression (β = 1.025, 95% CI: 0.237–1.812). Women were more likely to be influenced by the positive effect of parity; the association between late childbearing and health was only significant in the male group.

Conclusions

Parity and late childbearing are associated with cognitive function, activities of daily living, and symptoms of depression in the older adults in rural China. Older adults with more children might be in better health, and this finding is especially significant in women. However, late childbearing had a negative effect on multidimensional health, especially for men. The social mechanism and gender differences between reproductive history and health need to be further explored.

Multivariate analysis of independent roles of socioeconomic status, occupational physical activity, reproductive factors, and postmenopausal hormonal therapy in risk of breast cancer

PURPOSE

This case-control study assesses the independent roles of reproductive history, postmenopausal hormonal therapy (HT), socioeconomic status (SES), and occupational physical activity on the risk of breast cancer (BC).

METHODS

Odds ratios (OR) were estimated from conditional logistic multivariate regression model in a data set of 19,253 Finnish women diagnosed with BC between 1994 and 2013 and 96,265 age-matched population controls.

RESULTS

Both pre- and postmenopausal white-collar workers had significantly increased risk of ductal and lobular BC as compared to manual workers. Moderate occupational physical activity reduced risk of lobular BC by 14%. There was a transient increase in the risk of BC observed after each birth followed by a protective effect starting some years after the delivery. As the number of children increased, the short-term excess risk was lower and protective effect was observed earlier. Continuous estrogen-progestin therapy (EPT) significantly increased the risk of both ductal and lobular BC and the magnitude of risk was directly proportional to duration of use (OR for 5+ years of use 2.26, 95% confidence interval 2.12-2.42). Monthly EPT for 5+ years increased the risk (OR 1.32, 95% CI 1.20-1.45). Users of estradiol plus levonorgestrel intrauterine system devices showed ORs of 1.56 (95% CI 1.45-1.69) and 2.18 (95% CI 1.81-2.64) for ductal and lobular BC, respectively.

CONCLUSION

This study concludes that pregnancy has a dual effect on BC risk, with a transient increase in risk followed by a long-term protective effect. The SES and HT have a large effect on BC risk while occupational physical activity has only a small independent effect.

Cancer Susceptibility as a Cost of Reproduction and Contributor to Life History Evolution

Reproduction is one of the most energetically demanding life-history stages. As a result, breeding individuals often experience trade-offs, where energy is diverted away from maintenance (cell repair, immune function) toward reproduction. While it is increasingly acknowledged that oncogenic processes are omnipresent, evolving and opportunistic entities in the bodies of metazoans, the associations among reproductive activities, energy expenditure, and the dynamics of malignant cells have rarely been studied. Here, we review the diverse ways in which age-specific reproductive performance (e.g., reproductive aging patterns) and cancer risks throughout the life course may be linked via trade-offs or other mechanisms, as well as discuss situations where trade-offs may not exist. We argue that the interactions between host–oncogenic processes should play a significant role in life-history theory, and suggest some avenues for future research.

Activation of the viral sensor oligoadenylate synthetase 2 (Oas2) prevents pregnancy-driven mammary cancer metastases

BACKGROUND

The interferon response can influence the primary and metastatic activity of breast cancers and can interact with checkpoint immunotherapy to modulate its effects. Using N-ethyl-N-nitrosourea mutagenesis, we found a mouse with an activating mutation in oligoadenylate synthetase 2 (Oas2), a sensor of viral double stranded RNA, that resulted in an interferon response and prevented lactation in otherwise healthy mice.

METHODS

To determine if sole activation of Oas2 could alter the course of mammary cancer, we combined the Oas2 mutation with the MMTV-PyMT oncogene model of breast cancer and examined disease progression and the effects of checkpoint immunotherapy using Kaplan-Meier survival analysis with immunohistochemistry and flow cytometry.

RESULTS

Oas2 mutation prevented pregnancy from increasing metastases to lung. Checkpoint immunotherapy with antibodies against programmed death-ligand 1 was more effective when the Oas2 mutation was present.

CONCLUSIONS

These data establish OAS2 as a therapeutic target for agents designed to reduce metastases and increase the effectiveness of checkpoint immunotherapy.

MRI Evaluation of the Lactating Breast

Purpose of Review

To review the MRI appearance of physiologic lactational changes, common benign pathologies, and malignancies in the lactating breast.

Recent Findings

The prevalence of pregnancy-associated breast cancer has increased as more women delay childbirth and lactation. There is a transient increase in breast cancer risk after delivery when women may be lactating. MRI is more sensitive than mammography and ultrasound for the evaluation of the extent of disease in lactating women.

Summary

Understanding the key MRI findings of benign and malignant pathologies in the lactating breast is critical for accurate diagnosis and prompt evaluation of pregnancy-associated breast cancer.