Breast Cancer Risk After Recent Childbirth: A Pooled Analysis of 15 Prospective Studies

Lapses in breast cancer screening for highly penetrant mutation carriers during pregnancy and lactation

BACKGROUND AND OBJECTIVES

Screening for breast cancer in highly penetrant mutation carriers during pregnancy and lactation is challenging and consensus guidelines are lacking. This study evaluates the lapse in screening and the interval pregnancy-associated breast cancer rate.

METHODS

A single-institution retrospective cohort study of pregnant and lactating patients with known pathogenic germline mutations was performed. Lapse in screening was defined as the interval between the last screening imaging exam obtained before last menstrual period and the subsequent screening imaging.

RESULTS

Out of 685 patients, 42 had 1-3 evaluable pregnancies (54 total - 28 managed in High Risk Breast Clinic and 26 by OB/GYN). Mutations were observed in patients in BRCA1 (49%), BRCA2 (36%), CDH1 (5%), CHEK2 (2%), ATM (2%), NF1 (3%), and MSH2 (3%). The average screening lapse was 25 [19, 30] months for patients followed in the High Risk Clinic versus 32.5 [21, 65.75] months for patients followed with Routine Care (p = 0.035). We identified three cases of pregnancy-associated breast cancer (interval cancer rate 6%).

CONCLUSIONS

Patients with highly penetrant mutations are at risk for the development of interval pregnancy-associated breast cancer. Development of consistent screening guidelines and adherence to those guidelines is needed for this patient population.

Mammary collagen is under reproductive control with implications for breast cancer

Mammographically-detected breast density impacts breast cancer risk and progression, and fibrillar collagen is a key component of breast density. However, physiologic factors influencing collagen production in the breast are poorly understood. In female rats, we analyzed gene expression of the most abundantly expressed mammary collagens and collagen-associated proteins across a pregnancy, lactation, and weaning cycle. We identified a triphasic pattern of collagen gene regulation and evidence for reproductive state-dependent composition. An initial phase of collagen deposition occurred during pregnancy, followed by an active phase of collagen suppression during lactation. The third phase of collagen regulation occurred during weaning-induced mammary gland involution, which was characterized by increased collagen deposition. Concomitant changes in collagen protein abundance were confirmed by Masson's trichrome staining, second harmonic generation (SHG) imaging, and mass spectrometry. We observed similar reproductive-state dependent collagen patterns in human breast tissue obtained from premenopausal women. SHG analysis also revealed structural variation in collagen across a reproductive cycle, with higher packing density and more collagen fibers arranged perpendicular to the mammary epithelium in the involuting rat mammary gland compared to nulliparous and lactating glands. Involution was also characterized by high expression of the collagen cross-linking enzyme lysyl oxidase, which was associated with increased levels of cross-linked collagen. Breast cancer relevance is suggested, as we found that breast cancer diagnosed in recently postpartum women displayed gene expression signatures of increased collagen deposition and crosslinking compared to breast cancers diagnosed in age-matched nulliparous women. Using publically available data sets, we found this involution-like, collagen gene signature correlated with poor progression-free survival in breast cancer patients overall and in younger women. In sum, these findings of physiologic collagen regulation in the normal mammary gland may provide insight into normal breast function, the etiology of breast density, and inform breast cancer risk and outcomes.

Global, regional, and national cancer incidence and death for 29 cancer groups in 2019 and trends analysis of the global cancer burden, 1990-2019

Background and aims

Cancer will soon become the leading cause of death in every country in the twenty-first century. This study aimed to analyze the mortality and morbidity of 29 types of cancer in 204 countries or regions from 1990 to 2019 to guide global cancer prevention and control.

Methods

Detailed information for 29 cancer groups was collected from the Global Burden of Disease Study in 2019. The age-standardized incidence rate (ASIR) and age-standardized death rate (ASDR) of the 29 cancer groups were calculated based on sex, age, region, and country. In addition, separate analyses were performed for major cancer types.

Results

In 2019, more than 10 million people died from cancer, which was approximately twice the number in 1990. Tracheal, bronchus, and lung (TBL) cancers collectively showed the highest death rate, and the ASDR of pancreatic cancer increased by 24%, which was cancer with the highest case fatality rate (CFR). The global cancer ASIR showed an increasing trend, with testicular cancer, thyroid cancer, and malignant skin melanoma showing a significant increase. The ASDR and ASIR of cancer in males were about 1.5 times higher than that in females. Individuals over 50 years had the highest risk of developing cancer, with incidences and deaths in this age group accounting for more than 85% of cancers in all age groups. Asia has the heaviest cancer burden due to its high population density, with esophageal cancer in this region accounting for 53% of the total fatalities related to this type of cancer in the world. In addition, the mortality and morbidity of most cancers increased with the increase in the development or socio-demographic index (SDI) in the SDI regions based on the World Bank's Human Development Index (HDI), with cancer characteristics varying in the different countries globally.

Conclusions

The global cancer burden continues to increase, with substantial mortality and morbidity differences among the different regions, ages, countries, gender, and cancer types. Effective and locally tailored cancer prevention and control measures are essential in reducing the global cancer burden in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-021-01213-z.

A Review of Breast Cancer Risk Factors in Adolescents and Young Adults

Simple Summary

Cancer diagnosed in patients between the ages of 15 and 39 deserves special consideration. Diagnoses within this cohort of adolescents and young adults include childhood cancers which present at an older age than expected, or an early presentation of cancers that are typically observed in older adults, such as breast cancer. Cancers within this age group are associated with worse disease-free and overall survival rates, and the incidence of these cases are rising. Knowing an individual’s susceptibility to disease can change their clinical management and allow for the risk-testing of relatives. This review discusses the risk factors that contribute to breast cancer in this unique cohort of patients, including inherited genetic risk factors, as well as environmental and lifestyle factors. We also describe risk models that allow clinicians to quantify a patient’s lifetime risk of developing disease.

Abstract

Cancer in adolescents and young adults (AYAs) deserves special consideration for several reasons. AYA cancers encompass paediatric malignancies that present at an older age than expected, or early-onset of cancers that are typically observed in adults. However, disease diagnosed in the AYA population is distinct to those same cancers which are diagnosed in a paediatric or older adult setting. Worse disease-free and overall survival outcomes are observed in the AYA setting, and the incidence of AYA cancers is increasing. Knowledge of an individual’s underlying cancer predisposition can influence their clinical care and may facilitate early tumour surveillance strategies and cascade testing of at-risk relatives. This information can further influence reproductive decision making. In this review we discuss the risk factors contributing to AYA breast cancer, such as heritable predisposition, environmental, and lifestyle factors. We also describe a number of risk models which incorporate genetic factors that aid clinicians in quantifying an individual’s lifetime risk of disease.

Breast Cancer Risk Factors and Circulating Anti-Müllerian Hormone Concentration in Healthy Premenopausal Women

CONTEXT

We previously reported that anti-Müllerian hormone (AMH), a marker of ovarian reserve, is positively associated with breast cancer risk, consistent with other studies.

OBJECTIVE

This study assessed whether risk factors for breast cancer are correlates of AMH concentration.

METHODS

This cross-sectional study included 3831 healthy premenopausal women (aged 21-57, 87% aged 35-49) from 10 cohort studies among the general population.

RESULTS

Adjusting for age and cohort, AMH positively associated with age at menarche (P < 0.0001) and parity (P = 0.0008) and inversely associated with hysterectomy/partial oophorectomy (P = 0.0008). Compared with women of normal weight, AMH was lower (relative geometric mean difference 27%, P < 0.0001) among women who were obese. Current oral contraceptive (OC) use and current/former smoking were associated with lower AMH concentration than never use (40% and 12% lower, respectively, P < 0.0001). We observed higher AMH concentrations among women who had had a benign breast biopsy (15% higher, P = 0.03), a surrogate for benign breast disease, an association that has not been reported. In analyses stratified by age (<40 vs ≥40), associations of AMH with body mass index and OCs were similar in younger and older women, while associations with the other factors (menarche, parity, hysterectomy/partial oophorectomy, smoking, and benign breast biopsy) were limited to women ≥40 (P-interaction < 0.05).

CONCLUSION

This is the largest study of AMH and breast cancer risk factors among women from the general population (not presenting with infertility), and it suggests that most associations are limited to women over 40, who are approaching menopause and whose AMH concentration is declining.

Free Time For Wellness: a co-designed intervention utilizing social networks to encourage physical activity for cancer prevention among low resourced mothers

BACKGROUND

Physical activity is central to chronic disease prevention. Low resource mothers face structural barriers preventing them from increasing their physical activity to reduce their chronic disease risk. We co-designed an intervention, with the ultimate goal of building social cohesion through social media to increase physical activity for low resourced mothers in urban settings.

METHODS

In 2019, we interviewed 10 mothers of children (< 12 years) living in Washington Heights, Manhattan. The interviews were transcribed and coded for themes that guided the creation of a co-design workshop. Washington Heights-based mothers (n = 16) attended a co-design workshop to generate the blueprint for the Free Time for Wellness intervention.

RESULTS

Mothers in our sample had limited time, external support and resources, which hindered them from increasing their physical activity; we learned that in addition to physical health, mental health was a concern for participants. Participants had varying degrees of self-efficacy and trust in social media. Bringing mothers and researchers together in a co-design workshop, we identified types of physical activities they would enjoy participating in, the ideal time to do so, the kind of childcare they needed, and their preferences for communication with the community champion. The interviews and workshop highlighted the need for a community space that mothers and children could co-occupy. The intervention was designed to be 3 months' worth of sample programming with one activity per week, rotating between dance, yoga, food pantry visits and group playdates. Participants were invited to bring their children to a space with one room for the 'participants only' activity and a second room in which professional childcare providers supervised the children.

CONCLUSIONS

Through this two-phased co-design process, we created an intervention with mothers in an urban community with the goal of using social media to bring them together for wellness, primarily through increased physical activity. Despite the co-design of this intervention with a specific community, there are some universal applications of our findings, and of the use of co-design workshops, to other settings.

Epidemiology of Triple-Negative Breast Cancer: A Review

ABSTRACT

Triple-negative breast cancer accounted for 12% of breast cancers diagnosed in the United States from 2012 to 2016, with a 5-year survival 8% to 16% lower than hormone receptor-positive disease. However, preventive and screening strategies remain tailored to the demographics of less lethal luminal cancers. This review examines the ethnic, genetic, and modifiable risk factors associated with triple-negative breast cancer, which providers must recognize to address the societal disparities of this deadly disease. Most notable is that triple-negative cancers disproportionately affect African American women and carriers of germline BRCA and PALB2 mutations. Even controlling for treatment delays, stage, and socioeconomic factors, African Americans with triple-negative breast cancer remain nearly twice as likely to die of their disease. To level the playing field, we must integrate genomic predictors of disease and epidemiologic characteristics of molecular breast cancer subtypes to provide personalized risk assessment, screening, and treatment for each patient.

Reproductive issues in carriers of germline pathogenic variants in the BRCA1/2 genes: an expert meeting

BACKGROUND

Healthy individuals and patients with cancer who are carriers of germline pathogenic variants in the BRCA1/2 genes face multiple reproductive challenges that require appropriate counseling and specific expertise.

MAIN BODY

On December 5th-7th, 2019, patient advocates and physicians with expertise in the field of reproductive medicine, fertility preservation, and oncology were invited to "San Giuseppe Moscati" Hospital in Avellino (Italy) for a workshop on reproductive management of women with germline pathogenic variants in the BRCA1/2 genes. From the discussion regarding the current evidence and future prospective in the field, eight main research questions were formulated and eight recommendations were developed regarding fertility, fertility preservation, preimplantation genetic testing, and pregnancy in healthy carriers and patients with cancer.

CONCLUSION

Several misconceptions about the topic persist among health care providers and patients often resulting in a discontinuous and suboptimal management. With the aim to offer patient-tailored counseling about reproductive issues, both awareness of current evidences and research should be promoted.

The impact of endogenous estrogen exposures on the characteristics and outcomes of estrogen receptor positive, early breast cancer

BACKGROUND

Menstrual and parity history might impact the risk for breast cancer. Data on the impact of these factors on other tumor characteristics are limited.

METHODS

A single center retrospective cohort study comprising all women with estrogen receptor (ER) positive, human epidermal growth factor receptor 2 (HER2) negative, early breast cancer whose tumors were sent to OncotypeDX analysis. The prespecified subgroups were investigated: age of menarche (< 12 vs. ≥ 12 years), number of deliveries (0 vs. ≥ 1 childbirth and ≥ 5 childbirth vs. other), age of first delivery (≥ 30 years vs. younger age) and postmenopausal compared to premenopausal. The impact of age of menopause was also assessed categorically, using early (< 45 years) and late age of menopause (> 55 years). Differences in tumor characteristics were evaluated using T-test or Mann Whitney for continuous variables or Fisher's exact test for categorical variables. Outcomes were assessed by Kaplan-Meier survival analysis, with the log-rank test.

RESULTS

A total of 620 women were included. After median follow-up of 10.4 years, early menopause was associated with significantly worse disease-free survival (HR = 2.26, p = 0.004) and overall-survival (HR = 2.60, p = 0.004), and multiparity was associated with significant worse disease-free survival (HR = 2.16, p = 0.026). These differences remain significant in multivariate analyses. Post-menopausal women were more likely to have stronger ER intensity (p = 0.002) but progesterone receptor (PR) positivity was less frequent (p = 0.009(. Early age of menarche was associated with PR positivity (p = 0.039). No other associations were found between the evaluated subgroups and tumor characteristics.

CONCLUSIONS

The impact of endogenous estrogen exposure had little effect on breast cancer characteristics of early stage, luminal disease. Early menopause and multiparity were associated with worse outcome.

Vitamin D as a Potential Preventive Agent For Young Women's Breast Cancer

Clinical studies backed by research in animal models suggest that vitamin D may protect against the development of breast cancer, implicating vitamin D as a promising candidate for breast cancer prevention. However, despite clear preclinical evidence showing protective roles for vitamin D, broadly targeted clinical trials of vitamin D supplementation have yielded conflicting findings, highlighting the complexity of translating preclinical data to efficacy in humans. While vitamin D supplementation targeted to high-risk populations is a strategy anticipated to increase prevention efficacy, a complimentary approach is to target transient, developmental windows of elevated breast cancer risk. Postpartum mammary gland involution represents a developmental window of increased breast cancer promotion that may be poised for vitamin D supplementation. Targeting the window of involution with short-term vitamin D intervention may offer a simple, cost-effective approach for the prevention of breast cancers that develop postpartum. In this review, we highlight epidemiologic and preclinical studies linking vitamin D deficiency with breast cancer development. We discuss the underlying mechanisms through which vitamin D deficiency contributes to cancer development, with an emphasis on the anti-inflammatory activity of vitamin D. We also discuss current evidence for vitamin D as an immunotherapeutic agent and the potential for vitamin D as a preventative strategy for young woman's breast cancer.

Young breast cancer and the influence of ethnicity in Sandakan: A 3-year retrospective cross-sectional study

INTRODUCTION

Breast cancer (BC) is the most common cancer in Malaysia, with incidence increasing with age. There have been demonstrated differences in age of presentation and tumour biology when comparing ethnicities. Twenty percent of Caucasian women present before 50 years old, but almost 50% of Southeast Asian (SEA) women present before 50. However, BC in Indigenous sub-groups has not yet been studied. Sandakan is a city in Sabah with a large Indigenous population. Current nationwide screening guidelines are based on the U.S. Preventive Task Force 2009 Guidelines, which may not represent our population. We aim to examine the age of incidence for our local population, for local screening recommendations.

METHOD

Retrospective cross-sectional study, including all consecutive cases of epithelial invasive tumours, from January 2016 to December 2018. Other histological types were excluded. Univariate and multivariate analyses were performed.

RESULT

A total of 115 breast tumours were identified. Ten tumours were excluded (five ductal carcinoma in situ, four phyllodes, and one sarcoma), leaving a study population of 105 patients. Median age of presentation was 53 years (min 30; max 97). A total of 41.9% presented before the age of 50. Patients of Indigenous ethnic origins were 11 years younger at presentation than non-Indigenous women. Tumour grade was more likely to be higher among Indigenous women.

CONCLUSION

Median age of presentation of BC in Sandakan matches regional data; however, patients of Indigenous ethnic groups present even earlier. Screening guidelines should consider the growing evidence of young BC in SEA.

Examining the etiology of early-onset breast cancer in the Canadian Partnership for Tomorrow's Health (CanPath)

PURPOSE

Breast cancer incidence among younger women (under age 50) has increased over the past 25 years, yet little is known about the etiology among this age group. The objective of this study was to investigate relationships between modifiable and non-modifiable risk factors and early-onset breast cancer among three prospective Canadian cohorts.

METHODS

A matched case-control study was conducted using data from Alberta's Tomorrow Project, BC Generations Project, and the Ontario Health Study. Participants diagnosed with breast cancer before age 50 were identified through provincial registries and matched to three control participants of similar age and follow-up. Conditional logistic regression was used to examine the association between factors and risk of early-onset breast cancer.

RESULTS

In total, 609 cases and 1,827 controls were included. A body mass index ≥ 30 kg/m² was associated with a lower risk of early-onset breast cancer (OR 0.65; 95% CI 0.47-0.90), while a waist circumference ≥ 88 cm was associated with an increased risk (OR 1.58; 95% CI 1.18-2.11). A reduced risk was found for women with ≥ 2 pregnancies (OR 0.76; 95% CI 0.59-0.99) and a first-degree family history of breast cancer was associated with an increased risk (OR 1.95; 95% CI 1.47-2.57).

CONCLUSIONS

In this study, measures of adiposity, pregnancy history, and familial history of breast cancer are important risk factors for early-onset breast cancer. Evidence was insufficient to conclude if smoking, alcohol intake, fruit and vegetable consumption, and physical activity are meaningful risk factors. The results of this study could inform targeted primary and secondary prevention for early-onset breast cancer.

Does it matter for the radiologists' performance whether they read short or long batches in organized mammographic screening?

Objective

To analyze the association between radiologists’ performance and image position within a batch in screen reading of mammograms in Norway.

Method

We described true and false positives and true and false negatives by groups of image positions and batch sizes for 2,937,312 screen readings performed from 2012 to 2018. Mixed-effects models were used to obtain adjusted proportions of true and false positive, true and false negative, sensitivity, and specificity for different image positions. We adjusted for time of day and weekday and included the individual variation between the radiologists as random effects. Time spent reading was included in an additional model to explore a possible mediation effect.

Result

True and false positives were negatively associated with image position within the batch, while the rates of true and false negatives were positively associated. In the adjusted analyses, the rate of true positives was 4.0 per 1000 (95% CI: 3.8–4.2) readings for image position 10 and 3.9 (95% CI: 3.7–4.1) for image position 60. The rate of true negatives was 94.4% (95% CI: 94.0–94.8) for image position 10 and 94.8% (95% CI: 94.4–95.2) for image position 60. Per 1000 readings, the rate of false negative was 0.60 (95% CI: 0.53–0.67) for image position 10 and 0.62 (95% CI: 0.55–0.69) for image position 60.

Conclusion

There was a decrease in the radiologists’ sensitivity throughout the batch, and although this effect was small, our results may be clinically relevant at a population level or when multiplying the differences with the number of screen readings for the individual radiologists.

Key Points

• True and false positive reading scores were negatively associated with image position within a batch.

• A decreasing trend of positive scores indicated a beneficial effect of a certain number of screen readings within a batch.

• False negative scores increased throughout the batch but the association was not statistically significant.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08010-9.

Effects of fertility on breast cancer incidence trends: comparing France and US

PURPOSE

Breast cancer incidence rates are now higher in France than most other European countries as well as the United States (US). Increasing breast cancer incidence rates globally have often been attributed to declining fertility rates.

METHODS

We compared temporal trends in breast cancer incidence in France and the US, and examined the extent temporal trends in national fertility rates can explain the temporal trends in breast cancer incidence. This study of temporal trends used estimates of annual percent change (APC) from cancer registry data in France and the US (1978-2016) and national fertility data (1958-2011). We estimated the APCs for all ages (overall APC) and for specific age groups (under 50, 50-64 years, and 65 years and over).

RESULTS

The overall APC was over three times higher in France than the US (France APC = 1.63%, 95% CI 1.43-1.84; US APC = 0.51, 95% CI 0.31-0.72). The overall APCs remained positive and statistically significant after adjusting for fertility trends irrespective of assumptions on fertility lags (France APC = 1.61-0.91 for a 5-year to 20-year lag, respectively; US APC = 0.37-0.36 for a 5-year to 20-year lag, respectively). Similarly, among women under 50, the APC was over 3.5 times higher in France than the US (France APC = 1.22, 95% CI 1.07-1.37; US APC = 0.33, 95% CI 0.22-0.44), and APCs remained positive after adjusting for fertility (France APC = 1.21-1.28 for a 5-year to 20-year lag, respectively; US APC = 0.38-0.26 for a 5-year to 20-year lag, respectively).

CONCLUSIONS

Based on these trend analyses, changes in fertility rate trends do not fully explain the increase incidence in breast cancer seen in both France and the US, nor the magnitude of difference between the two countries. This was seen overall and in age-specific groups.

Transiently increased risk of breast cancer after childbirth: implications for fertility treatments and surrogacy

Whereas longstanding dogma has purported that pregnancies protect women from breast cancer, a recent meta-analysis now mandates reconsideration since it reported an actual higher breast cancer risk for more than two decades after childbirth before the relative risk turns negative. Moreover, the risk of breast cancer appears higher for women having their first birth at an older age and with a family history and it is not reduced by breastfeeding. The process of obtaining informed consent for all fertility treatments, therefore, must make patients aware of the facts that every pregnancy, to a small degree, will increase the short-term breast cancer risk. This observation may be even more relevant in cases of surrogacy where women agree to conceive without deriving benefits of offspring from assuming the risk, thus creating a substantially different risk-benefit ratio. Consequently, it appears prudent for professional societies in the field to update recommendations regarding consent information for all fertility treatments but especially for treatments involving surrogacy.

[External validation of nomogram for the prediction of recurrences of pregnancy-associated breast cancer]

OBJECTIVE

Diagnosis and therapeutics are challenging in pregnancy-related breast cancer and a multidisciplinary approach is therefore essential. A nomogram predictive of recurrence at 36 months of PABC has recently been developed, the aim was to evaluate it on an independent cohort.

PATIENTS AND METHODS

This was a monocentric retrospective study including all patients with PABC between January 2004 and March 2018. A Kaplan-Meier method was used for the analysis of recurrence-free survival. Nomogram performance was analysed on 3 indicators: discrimination by a receiver operator characteristic curve (ROC), calibration and net clinical benefit by a decision curve analysis.

RESULTS

Forty-one patients have been included. The survival rate was 83 % at 3 years. The nomogram showed acceptable discrimination capacities on receiver-operator characteristic analysis (c-index: 0.78). Decision-curve analysis showed a positive net-benefit for relapse probability ranges between 5 % and 35 %.

CONCLUSION

The performance of this prediction model is acceptable but the net clinical benefit low. In conclusion, prediction of recurrence remains challenging with a continued need for more precise tools.

A Review of Modifiable Risk Factors in Young Women for the Prevention of Breast Cancer

Breast cancer is the most common cancer diagnosis in women aged less than 40 years and the second most common cause of cancer death in this age group. Global rates of young onset breast cancer have risen steadily over the last twenty years. Although young women with breast cancer have a higher frequency of underlying pathogenic mutations in high penetrance breast cancer susceptibility genes (CSG) than older women, the vast majority of young breast cancer patients are not found to have a germline CSG mutation. There is therefore a need to inform young women regarding non-genetic breast cancer risk factors which have the potential to be influenced by changes in individual behaviour. A Pubmed search was performed using the search terms “young” or “early onset”, and “breast cancer” and “modifiable risk”. Titles and abstracts from peer-reviewed publications were screened for relevance. This review presents evidence for potentially modifiable risk factors of breast cancer risk in young women, including lifestyle factors (physical activity, body habitus, alcohol use, smoking, shift work and socioeconomic factors), reproductive and hormonal factors and iatrogenic risks. The extent to which these factors are truly modifiable is discussed and interactions between genetic and non-genetic risk factors are also addressed. Health care professionals have an opportunity to inform young women about breast health and risk when presenting at a “teachable moment”, including the benefits of physical activity and alcohol habits as risk factor. More focussed discussions regarding individual personal risk and benefit should accompany conversations regarding reproductive health and take into consideration both non-modifiable and iatrogenic BC risk factors.

Deep Learning Image Analysis of Benign Breast Disease to Identify Subsequent Risk of Breast Cancer

Background

New biomarkers of risk may improve breast cancer (BC) risk prediction. We developed a computational pathology method to segment benign breast disease (BBD) whole slide images into epithelium, fibrous stroma, and fat. We applied our method to the BBD BC nested case-control study within the Nurses' Health Studies to assess whether computer-derived tissue composition or a morphometric signature was associated with subsequent risk of BC.

Methods

Tissue segmentation and nuclei detection deep-learning networks were established and applied to 3795 whole slide images from 293 cases who developed BC and 1132 controls who did not. Percentages of each tissue region were calculated, and 615 morphometric features were extracted. Elastic net regression was used to create a BC morphometric signature. Associations between BC risk factors and age-adjusted tissue composition among controls were assessed using analysis of covariance. Unconditional logistic regression, adjusting for the matching factors, BBD histological subtypes, parity, menopausal status, and body mass index evaluated the relationship between tissue composition and BC risk. All statistical tests were 2-sided.

Results

Among controls, direction of associations between BBD subtypes, parity, and number of births with breast composition varied by tissue region; select regions were associated with childhood body size, body mass index, age of menarche, and menopausal status (all P < .05). A higher proportion of epithelial tissue was associated with increased BC risk (odds ratio = 1.39, 95% confidence interval = 0.91 to 2.14, for highest vs lowest quartiles, P trend  = .047). No morphometric signature was associated with BC.

Conclusions

The amount of epithelial tissue may be incorporated into risk assessment models to improve BC risk prediction.

Nonhuman primate model in mammary gland biology and neoplasia research

Research on breast cancer pathogenesis, prevention and drug development remains an important field as this disease is still one of the leading causes of cancer death worldwide. Nonhuman primates, particularly macaque species, may serve as a highly translational animal model in breast cancer studies due to their similarity with humans in genetics, anatomy, reproductive and endocrine physiology including mammary gland development profile. The use of nonhuman primates in biomedical research, however, requires high ethical standards and an increasing expectation to improve strategies to replace, reduce and refine their use. Here, we discuss some key features of nonhuman primate mammary gland biology relevant to their strengths and limitations as models in studies of breast development and cancer risk.

Breast cancer risk after hysterectomy with and without salpingo-oophorectomy for benign indications

BACKGROUND

Breast cancer risk has been extensively studied in women with genetic predisposition, that is, mutations in breast cancer genes 1 and 2. Although there are guidelines for performing bilateral salpingo-oophorectomies in individuals with specific genetic risks, oophorectomies are also performed in many women considered to be at average risk of developing breast cancer. The risk of breast cancer in women with average risk who undergo hysterectomy with bilateral salpingo-oophorectomy for benign indications is less clear.

OBJECTIVE

This study aimed to estimate breast cancer risk after hysterectomy with and without concomitant bilateral salpingo-oophorectomy for benign indications.

STUDY DESIGN

From 2001 to 2015, women aged 18 years and older from Kaiser Permanente Northern California who underwent hysterectomy alone and hysterectomy with bilateral salpingo-oophorectomy were identified using the International Classification of Diseases, Ninth Revision, procedure and Current Procedural Terminology codes. Women with a breast cancer gene mutation and previous history of breast cancer or gynecologic cancer were excluded. Descriptive and bivariate analyses were used to describe and compare demographic and clinical characteristics. Breast cancer incidence rates were calculated per 100,000 person-years. Survival analysis and Cox proportional hazard models were conducted to compare the risk of developing breast cancer.

RESULTS

Of 49,215 women who underwent hysterectomy, 19,826 had hysterectomy with bilateral salpingo-oophorectomy. Whites, Hispanics, blacks, Asians, and other or unknown comprised 51.2%, 20.3%, 12.7%, 10.4%, and 5.3% of the study population, respectively. The average age of women with hysterectomy alone was 45.5 years compared with 50.8 years for those who had hysterectomy with bilateral salpingo-oophorectomy. During the study period, 915 women received a diagnosis of breast cancer. Age-specific breast cancer incidence rates were higher in women older than 60 years with oophorectomy than hysterectomy alone (471.2 [95% confidence interval, 386.2-556.2] vs 463.0 [95% confidence interval, 349.6-576.5], respectively). After controlling for age, race, income, and Charlson Comorbidity Index, women with bilateral salpingo-oophorectomy had a 14% lower risk of breast cancer than women with hysterectomy alone (hazard ratio, 0.86; 95% confidence interval, 0.75-0.98). All-cause mortality was higher with oophorectomy than hysterectomy alone (64.4% vs 35.6%, P<.0001, respectively).

CONCLUSION

Women with concurrent bilateral salpingo-oophorectomy for benign indications had a lower risk of breast cancer than those who had hysterectomy alone. However, all-cause mortality was higher in women with oophorectomy. Perimenopausal patients undergoing hysterectomy for benign indications should be counseled on the risks and benefits of oophorectomy at the time of surgery.

Characterization of Organoid Cultures to Study the Effects of Pregnancy Hormones on the Epigenome and Transcriptional Output of Mammary Epithelial Cells

The use of mouse derived mammary organoids can provide a unique strategy to study mammary gland development across a normal life cycle, as well as offering insights into how malignancies form and progress. Substantial cellular and epigenomic changes are triggered in response to pregnancy hormones, a reaction that engages molecular and cellular changes that transform the mammary epithelial cells into "milk producing machines". Such epigenomic alterations remain stable in post-involution mammary epithelial cells and control the reactivation of gene transcription in response to re-exposure to pregnancy hormones. Thus, a system that tightly controls exposure to pregnancy hormones, epigenomic alterations, and activation of transcription will allow for a better understanding of such molecular switches. Here, we describe the characterization of ex vivo cultures to mimic the response of mammary organoid cultures to pregnancy hormones and to understand gene regulation and epigenomic reprogramming on consecutive hormone exposure. Our findings suggest that this system yields similar epigenetic modifications to those reported in vivo, thus representing a suitable model to closely track epigenomic rearrangement and define unknown players of pregnancy-induced development.

Risk factors for inflammatory and non-inflammatory breast cancer in North Africa

PURPOSE

Studies of the etiology of inflammatory breast cancer (IBC), a rare but aggressive breast cancer, have been hampered by limited risk factor information. We extend previous studies by evaluating a broader range of risk factors.

METHODS

Between 2009 and 2015, we conducted a case-control study of IBC at six centers in Egypt, Tunisia, and Morocco; enrolled were 267 IBC cases and for comparison 274 non-IBC cases and 275 controls, both matched on age and geographic area to the IBC cases. We administered questionnaires and collected anthropometric measurements for all study subjects. We used multiple imputation methods to account for missing values and calculated odds ratios (ORs) and 95% confidence intervals (CIs) using polytomous logistic regression comparing each of the two case groups to the controls, with statistical tests for the difference between the coefficients for the two case groups.

RESULTS

After multivariable adjustment, a livebirth within the previous 2 years (OR 4.6; 95% CI 1.8 to 11.7) and diabetes (OR 1.8; 95% CI 1.1 to 3.0) were associated with increased risk of IBC, but not non-IBC (OR 0.9; 95% CI 0.3 to 2.5 and OR 0.9; 95% CI 0.5 to 1.6 for livebirth and diabetes, respectively). A family history of breast cancer, inflammatory-like breast problems, breast trauma, and low socioeconomic status were associated with increased risk of both tumor types.

CONCLUSIONS

We identified novel risk factors for IBC and non-IBC, some of which preferentially increased risk of IBC compared to non-IBC. Upon confirmation, these findings could help illuminate the etiology and aid in prevention of this aggressive cancer.

Menstrual and reproductive characteristics and breast cancer risk by hormone receptor status and ethnicity: The Breast Cancer Etiology in Minorities study

We pooled multiethnic data from four population-based studies and examined associations of menstrual and reproductive characteristics with breast cancer (BC) risk by tumor hormone receptor (HR) status [defined by estrogen receptor (ER) and progesterone receptor (PR)]. We estimated odds ratios and 95% confidence intervals using multivariable logistic regression, stratified by age (<50, ≥50 years) and ethnicity, for 5,186 HR+ (ER+ or PR+) cases, 1,365 HR- (ER- and PR-) cases and 7,480 controls. For HR+ BC, later menarche and earlier menopause were associated with lower risk in non-Hispanic whites (NHWs) and Hispanics, and higher parity and longer breast-feeding were associated with lower risk in Hispanics and Asian Americans, and suggestively in NHWs. Positive associations with later first full-term pregnancy (FTP), longer interval between menarche and first FTP and shorter time since last FTP were limited to younger Hispanics and Asian Americans. Except for nulliparity, reproductive characteristics were not associated with risk in African Americans. For HR- BC, lower risk was associated with later menarche, except in African Americans and older Asian Americans and with longer breast-feeding in Hispanics and Asian Americans only. In younger African Americans, HR- BC risk associated with higher parity (≥3 vs. 1 FTP) was increased fourfold in women who never breast-fed, but not in those with a breast-feeding history, suggesting that breast-feeding may mitigate the adverse effect of higher parity in younger African American women. Further work needs to evaluate why menstrual and reproductive risk factors vary in importance according to age and ethnicity.

Automated Quantitative Measures of Terminal Duct Lobular Unit Involution and Breast Cancer Risk

BACKGROUND

Manual qualitative and quantitative measures of terminal duct lobular unit (TDLU) involution were previously reported to be inversely associated with breast cancer risk. We developed and applied a deep learning method to yield quantitative measures of TDLU involution in normal breast tissue. We assessed the associations of these automated measures with breast cancer risk factors and risk.

METHODS

We obtained eight quantitative measures from whole slide images from a benign breast disease (BBD) nested case-control study within the Nurses' Health Studies (287 breast cancer cases and 1,083 controls). Qualitative assessments of TDLU involution were available for 177 cases and 857 controls. The associations between risk factors and quantitative measures among controls were assessed using analysis of covariance adjusting for age. The relationship between each measure and risk was evaluated using unconditional logistic regression, adjusting for the matching factors, BBD subtypes, parity, and menopausal status. Qualitative measures and breast cancer risk were evaluated accounting for matching factors and BBD subtypes.

RESULTS

Menopausal status and parity were significantly associated with all eight measures; select TDLU measures were associated with BBD histologic subtype, body mass index, and birth index (P < 0.05). No measure was correlated with body size at ages 5-10 years, age at menarche, age at first birth, or breastfeeding history (P > 0.05). Neither quantitative nor qualitative measures were associated with breast cancer risk.

CONCLUSIONS

Among Nurses' Health Studies women diagnosed with BBD, TDLU involution is not a biomarker of subsequent breast cancer.

IMPACT

TDLU involution may not impact breast cancer risk as previously thought.

A case-control study of the joint effect of reproductive factors and radiation treatment for first breast cancer and risk of contralateral breast cancer in the WECARE study

Objective

To examined the impact of reproductive factors on the relationship between radiation treatment (RT) for a first breast cancer and risk of contralateral breast cancer (CBC).

Methods

The Women’s Environmental Cancer and Radiation Epidemiology (WECARE) Study is a multi-center, population-based case-control study where cases are women with asynchronous CBC (N = 1521) and controls are women with unilateral breast cancer (N = 2211). Rate ratios (RR) and 95% confidence intervals (CI) were estimated using conditional logistic regression to assess the independent and joint effects of RT (ever/never and location-specific stray radiation dose to the contralateral breast [0, >0-<1Gy, ≥1Gy]) and reproductive factors (e.g., parity).

Results

Nulliparous women treated with RT (≥1Gy dose) were at increased risk of CBC compared with nulliparous women not treated with RT, although this relationship did not reach statistical significance (RR = 1.34, 95% CI 0.87, 2.07). Women treated with RT who had an interval pregnancy (i.e., pregnancy after first diagnosis and before second diagnosis [in cases]/reference date [in controls]) had an increased risk of CBC compared with those who had an interval pregnancy with no RT (RR = 4.60, 95% CI 1.16, 18.28). This was most apparent for women with higher radiation doses to the contralateral breast.

Conclusion

Among young female survivors of breast cancer, we found some evidence suggesting that having an interval pregnancy could increase a woman’s risk of CBC following RT for a first breast cancer. While sampling variability precludes strong interpretations, these findings suggest a role for pregnancy and hormonal factors in radiation-associated CBC.

•

Radiation treatment is associated with increased contralateral breast cancer risk in some women.

•

Reproductive status at the time of treatment may modify this relationship.

•

Some evidence that pregnancy after radiation treatment increases contralateral breast cancer risk.

Comparative Oncology: New Insights into an Ancient Disease

Cancer has deep evolutionary roots and is an important source of selective pressure in organismal evolution. Yet, we find a great deal of variation in cancer vulnerabilities across the tree of life. Comparative oncology offers insights into why some species vary in their susceptibility to cancer and the mechanisms responsible for the diversity of cancer defenses. Here we provide an overview for why cancer persists across the tree of life. We then summarize current data on cancer in mammals, reptiles, and birds in comparison with commonly reported human cancers. We report on both novel and shared mechanisms of cancer protection in animals. Cross-discipline collaborations, including zoological and aquarium institutions, wildlife and evolutionary biologists, veterinarians, medical doctors, cancer biologists, and oncologists, will be essential for progress in the field of comparative oncology. Improving medical treatment of humans and animals with cancer is the ultimate promise of comparative oncology.

Relationships between Breast Feeding and Breast Cancer Subtypes: Lessons Learned from Studies in Humans and in Mice

There are differential risk relationships between parity and breast cancer according to estrogen receptor (ER) status, with an increased risk of ER^- disease reduced by breastfeeding. This may be particularly relevant for understanding the higher incidence of ER^- tumors in Black women, who are more likely to be parous and less likely to breastfeed than other U.S. groups. Potential mechanisms for these relationships may include effects of disordered breast involution on inflammatory milieu in the breast as well as epigenetic reprogramming in the mammary gland, which can affect cell fate decisions in progenitor cell pools. In normal breast tissue, parity has been associated with hypermethylation of FOXA1, a pioneer transcription factor that promotes the luminal phenotype in luminal progenitors, while repressing the basal phenotype. In breast tumors, relationships between FOXA1 methylation and parity were strongest among women who did not breastfeed. Here, we summarize the epidemiologic literature regarding parity, breastfeeding, and breast cancer subtypes, and review potential mechanisms whereby these factors may influence breast carcinogenesis, with a focus on effects on progenitor cell pools in the mammary gland.

Prognosis of pregnancy-associated breast cancer: a meta-analysis

BACKGROUND

Pregnancy-associated breast cancer (PABC) is defined as breast cancer that is diagnosed during pregnancy and/or the postpartum period. Definitions of the duration of the postpartum period have been controversial, and this variability may lead to diverse results regarding prognosis. Moreover, evidence on the dose-response association between the time from the last pregnancy to breast cancer diagnosis and overall mortality has not been synthesized.

METHODS

We systematically searched PubMed, Embase, and the Cochrane Library for observational studies on the prognosis of PABC published up to June 1, 2019. We estimated summary-adjusted hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs). Subgroup analyses based on diagnosis time, PABC definition, geographic region, year of publication and estimation procedure for HR were performed. Additionally, dose-response analysis was conducted by using the variance weighted least-squares regression (VWLS) trend estimation.

RESULTS

A total of 54 articles (76 studies) were included in our study. PABC was associated with poor prognosis for overall survival (OS), disease-free survival (DFS) and cause-specific survival (CSS), and the pooled HRs with 95% CIs were 1.45 (1.30-1.63), 1.39 (1.25-1.54) and 1.40 (1.17-1.68), respectively. The corresponding reference category was non-PABC patients. According to subgroup analyses, the varied definition of PABC led to diverse results. The dose-response analysis indicated a nonlinear association between the time from the last delivery to breast cancer diagnosis and the HR of overall mortality (P < 0.001). Compared to nulliparous women, the mortality was almost 60% higher in women with PABC diagnosed at 12 months after the last delivery (HR = 1.59, 95% CI 1.30-1.82), and the mortality was not significantly different at 70 months after the last delivery (HR = 1.14, 95% CI 0.99-1.25). This finding suggests that the definition of PABC should be extended to include patients diagnosed up to approximately 6 years postpartum (70 months after the last delivery) to capture the increased risk.

CONCLUSION

This meta-analysis suggests that PABC is associated with poor prognosis, and the definition of PABC should be extended to include patients diagnosed up to approximately 6 years postpartum.

Immune Responses and Risk of Triple-negative Breast Cancer: Implications for Higher Rates among African American Women

The etiology of triple-negative breast cancers (TNBC) is poorly understood. As many TNBCs develop prior to the initiation of breast cancer screening or at younger ages when the sensitivity of mammography is comparatively low, understanding the etiology of TNBCs is critical for discovering novel prevention approaches for these tumors. Furthermore, the higher incidence rate of estrogen receptor-negative breast cancers, and specifically, of TNBCs, among young African American women (AAW) versus white women is a source of racial disparities in breast cancer mortality. Whereas immune responses to TNBCs have received considerable attention in relation to prognosis and treatment, the concept that dysregulated immune responses may predispose to the development of TNBCs has received limited attention. We present evidence that dysregulated immune responses are critical in the pathogenesis of TNBCs, based on the molecular biology of the cancers and the mechanisms proposed to mediate TNBC risk factors. Furthermore, proposed risk factors for TNBC, especially childbearing without breastfeeding, high parity, and obesity, are more prevalent among AAW than white women. Limited data suggest genetic differences in immune responses by race, which favor a stronger Thr type 2 (Th2) immune response among AAW than white women. Th2 responses contribute to wound-healing processes, which are implicated in the pathogenesis of TNBCs. Accordingly, we review data on the link between immune responses and TNBC risk and consider whether the prevalence of risk factors that result in dysregulated immunity is higher among AAW than white women.

Incidence and Survival by Human Epidermal Growth Factor Receptor 2 Status in Young Women With Stage I-III Breast Cancer: SEER, 2010-2016

BACKGROUND

Young premenopausal women with breast cancer often experience more aggressive disease biology and poorer survival than older women. Diagnostic and therapeutic advances, including human epidermal growth factor receptor 2 (HER2)-directed therapy, may lessen treatment burden and improve survival for these young women, but contemporary incidence and survival data by HER2 status are limited.

PATIENTS AND METHODS

We identified women aged 20-49 years (n = 68,530) diagnosed with stage I-III breast cancer during 2010-2016 from the United States Surveillance, Epidemiology, and End Results 18 registries database. Age-adjusted average annual percent changes in incidence (diagnosis 2010-2016) and 5-year Kaplan-Meier survival curves (diagnosis 2010-2015) were estimated by HER2 and hormone receptor (HR) status and stratified independently by cancer stage and race/ethnicity.

RESULTS

With increasing age decade, proportions of HER2-/HR+ cancer increased, whereas proportions of HER2+/HR+, HER2+/HR-, and HER2-/HR- decreased. The greatest increases in incidence during 2010-2016 were observed for HER2+ among women aged 20-49 years and HER2-/HR- among women aged 20-29 years. Incidence decreased for HER2-/HR- among women aged 40-49 years. Five-year survival was lowest for HER2-/HR- status compared to other receptor-based subtypes among women aged 20-49 years. HER2+ status was more beneficial for 5-year survival than HR+ status among women aged 20-29 years, with the opposite observed among women aged 30-49 years, particularly those aged 40-49 years.

CONCLUSION

HER2+ breast cancer increased among premenopausal women and was also associated with higher early survival within each HR status. HER2-/HR- cancer also increased among women aged 20-29 years and was associated with lower early survival. Our contemporary data provide important insights to help inform preventive and therapeutic strategies for premenopausal women.

Breast Cancer Risk and Use of Nonsteroidal Anti-inflammatory Agents After a Benign Breast Biopsy

Over one million women in the United States receive biopsy diagnoses of benign breast disease (BBD) each year, which confer a 1.5-4.0-fold increase in breast cancer risk. Studies in the general population suggest that nonsteroidal anti-inflammatory agents (NSAID) lower breast cancer risk; however, associations among women with BBD are unknown. We assessed whether NSAID use among women diagnosed with BBD is associated with lower breast cancer risk. Participants included 3,080 women (mean age = 50.3 ± 13.5 years) in the Mayo BBD surgical biopsy cohort diagnosed between January 1, 1992 and December 31, 2001 who completed breast cancer risk factor questionnaires that assessed NSAID use, and whose biopsies underwent detailed pathology review, masked to outcome. Women were followed from date of BBD biopsy to breast cancer diagnosis (main outcome) or censoring (death, prophylactic mastectomy, reduction mammoplasty, lobular carcinoma in situ or last contact). Median follow-up time was 16.4 ± 6.0 years. Incident breast cancer was diagnosed among 312 women over a median follow-up of 9.9 years. Regular non-aspirin NSAID use was associated with lower breast cancer risk [HR = 0.63; 95% confidence interval (CI) = 0.46-0.85; P = 0.002] with trends of lower risk (highest tertiles of use vs. nonuse) for greater number of years used [HR = 0.55; 95% CI = 0.31-0.97; P _trend = 0.003), days used per month (HR = 0.51; 95% CI = 0.33-0.80; P _trend = 0.001) and lifetime number of doses taken (HR = 0.53; 95% CI = 0.31-0.89; P _trend = 0.003). We conclude that nonaspirin NSAID use is associated with statistically significant lower breast cancer risk after a BBD biopsy, including a dose-response effect, suggesting a potential role for NSAIDs in breast cancer prevention among patients with BBD.

Effects of Germline Pathogenic Variants, Cancer Subtypes, Tumor-related Characteristics, and Pregnancy-associated Diagnosis on Outcomes

BACKGROUND

Although breast cancer (BC) is uncommon in women age ≤ 35 years, women in this age group may have more aggressive cancer subtypes and high-risk pathogenic variants (HRPVs). Higher recurrence and mortality rates in young patients may be related to differences in tumor biology, pathologic mutation status, or treatment. The purpose of this study was to evaluate germline mutation status and other factors that affect recurrence-free survival (RFS) and overall survival (OS) in young women with BC.

MATERIALS AND METHODS

This was a retrospective study of women diagnosed with BC at age ≤ 35 years at Allina Health System from 2000 through 2017 (n = 306). Information was collected on germline mutation status, tumor characteristics (grade, hormone receptor, and human epidermal growth factor receptor 2), molecular subtype, pregnancy-associated cancers, and treatment. Survival analyses using Kaplan-Meier curves were conducted for RFS and OS.

RESULTS

With mean follow-up of 6.5 years, OS was 87.0% for invasive cancers, RFS was 84.7%; 69% obtained genetic testing, and 26.9% had HRPVs. There were no differences in RFS or OS between patients with HRPV versus unknown/low/moderate risk variants. Recurrence analysis showed increased recurrence rates in luminal B-like cancers followed by triple negative and human epidermal growth factor receptor 2-positive cancers (P = .041). Pregnancy-associated BC diagnoses, angiolymphatic invasion, and tumor stage were associated with reduced OS. In spite of young age at diagnosis, nearly one-third of patients did not receive germline genetic testing.

CONCLUSIONS

Similar survival patterns were found between women with HRPV versus no known mutations. Luminal B-like subtype, pregnancy-associated BC, angiolymphatic invasion, and cancer stage were associated with reduced OS.

Female breast cancer mortality in relation to puberty on Staten Island, New York

Pursuant to a Congressional act in 2008, the Department of Health and Human Services established the Interagency Breast Cancer and Environmental Research Coordinating Committee to address the burden of breast cancer in the United States. Subsequently, the Committee recommended researchers study the timing of exposure to breast cancer risk factors. Given the high breast cancer mortality rate on Staten Island, this paper presents a case-control study investigating breast cancer risk associated with puberty while living on Staten Island. The dataset combined New York City Department of Health and Mental Hygiene female death certificate information between 1985 and 2006, with life history information from newspaper obituaries. Data analyzed included: age, length of residence on Staten Island, birth on Staten Island, and residence on Staten Island during puberty. Cases were individuals who died of breast cancer and controls were individuals who died of non-malignant causes. Analysis included multivariate logistic regression on the full dataset and multiple replicates of randomized one case to two controls simulations. Results indicated that living on Staten Island during puberty (ages 9-19) was associated with an elevated risk of dying from breast cancer (odds ratio 1.35, p < 0.001, 95% CI = 1.18, 1.55). This paper suggests the importance of studying puberty as a window of susceptibility for breast cancer risk.

Underlying Breast Cancer Risk and Menopausal Hormone Therapy

The recent Collaborative Group on Hormonal Factors in Breast Cancer (CGHFBC) publication calculated the attributable risk of breast cancer from use of estrogen alone and estrogen plus a synthetic progestogen for less than 5 to 15 or more years of use. This CGHFB report calculated attributable risk based on their findings of relative risk from pooled data from 58 studies. Notably, neither the CGHFBC nor other previous studies have examined the effect of underlying risk of breast cancer on attributable risk. This omission prompted us to determine the magnitude of the effect of underlying risk on attributable risk in this perspective. Meaningful communication of the potential risk of menopausal hormonal therapy requires providing women with the estimated risk above their existing underlying risk (ie, attributable risk). Therefore, we have estimated attributable risks from the data published by the CGHFBC, taking into account varying degrees of underlying risk. Based on the Endocrine Society Guideline on Menopausal Hormone Therapy (MHT), we divided groups into 3 categories of risk: low (1.5%), intermediate (3.0%), and high (6.0%) underlying risk of breast cancer over 5 years. In women taking estrogen plus a synthetic progestogen for 5 to 9 years, the attributable risks of MHT increased from 12, to 42, to 85 additional women per 1000 in the low-, intermediate-, and high-risk groups, respectively. The attributable risks for estrogen alone were lower but also increased based on underlying risk. Notably, the attributable risks were amplified with duration of MHT use, which increased both relative risk and breast cancer incidence.

Pregnancy reprograms the epigenome of mammary epithelial cells and blocks the development of premalignant lesions

Pregnancy causes a series of cellular and molecular changes in mammary epithelial cells (MECs) of female adults. In addition, pregnancy can also modify the predisposition of rodent and human MECs to initiate oncogenesis. Here, we investigate how pregnancy reprograms enhancer chromatin in the mammary epithelium of mice and influences the transcriptional output of the oncogenic transcription factor cMYC. We find that pregnancy induces an expansion of the active cis-regulatory landscape of MECs, which influences the activation of pregnancy-related programs during re-exposure to pregnancy hormones in vivo and in vitro. Using inducible cMYC overexpression, we demonstrate that post-pregnancy MECs are resistant to the downstream molecular programs induced by cMYC, a response that blunts carcinoma initiation, but does not perturb the normal pregnancy-induced epigenomic landscape. cMYC overexpression drives post-pregnancy MECs into a senescence-like state, and perturbations of this state increase malignant phenotypic changes. Taken together, our findings provide further insight into the cell-autonomous signals in post-pregnancy MECs that underpin the regulation of gene expression, cellular activation, and resistance to malignant development.

Mammary epithelial cells are epigenetically modified during pregnancy, these changes can influence the pre-disposition to cancer. Here, the authors examine the epigenetic landscape of mammary epithelial cells pre and post pregnancy and identify changes to the epigenetic landscape, which can protect mice from Myc induced cancer.

Gestational Diabetes and Risk of Breast Cancer in African American Women

BACKGROUND

Gestational diabetes mellitus (GDM) has been hypothesized to increase breast cancer risk, but results from the few prior epidemiologic studies are conflicting, and no studies have examined the association in African American women.

METHODS

We analyzed data from the prospective Black Women's Health Study to evaluate associations of history of GDM with breast cancer risk among 41,767 parous African American women, adjusting for potential confounders. HRs and 95% confidence intervals (CI) were estimated from multivariable Cox proportional hazards regression models.

RESULTS

There was no evidence of an association between history of GDM and risk of invasive breast cancer, overall or by estrogen receptor status.

CONCLUSIONS

Results of this study do not support the hypothesis that GDM is an important risk factor for breast cancer in African American women overall.

IMPACT

On the basis of these data, breast cancer risk is not increased among African American women with a history of GDM compared with parous women without a history of GDM.

Postpartum breast cancer progression is driven by semaphorin 7a-mediated invasion and survival

Young women diagnosed with breast cancer (BC) have poor prognosis due to increased rates of metastasis. In addition, women diagnosed within 10 years of most recent childbirth are approximately three times more likely to develop metastasis than age- and stage-matched nulliparous women. We define these cases as postpartum BC (PPBC) and propose that the unique biology of the postpartum mammary gland drives tumor progression. Our published results revealed roles for SEMA7A in breast tumor cell growth, motility, invasion, and tumor-associated lymphangiogenesis, all of which are also increased in preclinical models of PPBC. However, whether SEMA7A drives progression in PPBC remains largely unexplored. Our results presented herein show that silencing of SEMA7A decreases tumor growth in a model of PPBC, while overexpression is sufficient to increase growth in nulliparous hosts. Further, we show that SEMA7A promotes multiple known drivers of PPBC progression including tumor-associated COX-2 expression and fibroblast-mediated collagen deposition in the tumor microenvironment. In addition, we show for the first time that SEMA7A-expressing cells deposit fibronectin to promote tumor cell survival. Finally, we show that co-expression of SEMA7A/COX-2/FN predicts for poor prognosis in breast cancer patient cohorts. These studies suggest SEMA7A as a key mediator of BC progression, and that targeting SEMA7A may open avenues for novel therapeutic strategies.

Current Resources for Evidence-Based Practice, March 2020

An extensive review of new resources to support the provision of evidence-based care for women and infants. The current column includes a discussion of the concept of overdiagnosis and implications for research and commentaries on reviews focused on exogenous progestogen to maintain pregnancies and cancer risk among children conceived using fertility treatments.

[Desire for pregnancy and breast cancer]

Breast cancer affects about 3,000 new women of childbearing age each year. The desire for pregnancy is therefore a frequent issue in the management of breast cancer. We reviewed the current state of knowledge and recommendations in high-risk women, on the consideration of this desire for pregnancy in therapeutic management, the way to approach it, the preservation of fertility in the care process and finally on the outcomes of pregnancy after breast cancer. We evaluated the desire for pregnancy, qualitatively and quantitatively, after breast cancer through a literature review.

Environmental Exposures during Puberty: Window of Breast Cancer Risk and Epigenetic Damage

During puberty, a woman’s breasts are vulnerable to environmental damage (“window of vulnerability”). Early exposure to environmental carcinogens, endocrine disruptors, and unhealthy foods (refined sugar, processed fats, food additives) are hypothesized to promote molecular damage that increases breast cancer risk. However, prospective human studies are difficult to perform and effective interventions to prevent these early exposures are lacking. It is difficult to prevent environmental exposures during puberty. Specifically, young women are repeatedly exposed to media messaging that promotes unhealthy foods. Young women living in disadvantaged neighborhoods experience additional challenges including a lack of access to healthy food and exposure to contaminated air, water, and soil. The purpose of this review is to gather information on potential exposures during puberty. In future directions, this information will be used to help elementary/middle-school girls to identify and quantitate environmental exposures and develop cost-effective strategies to reduce exposures.

Prediagnostic Immune Cell Profiles and Breast Cancer

IMPORTANCE

Higher overall leukocyte counts in women may be associated with increased risk of breast cancer, but the association of specific leukocyte subtypes with breast cancer risk remains unknown.

OBJECTIVE

To determine associations between circulating leukocyte subtypes and risk of breast cancer.

DESIGN, SETTING, AND PARTICIPANTS

Between 2003 and 2009, the Sister Study enrolled 50 884 women who had a sister previously diagnosed with breast cancer but were themselves breast cancer free. A case-cohort subsample was selected in July 2014 from the full Sister Study cohort. Blood samples were obtained at baseline, and women were followed up through October 2016. Data analysis was performed in April 2019.

MAIN OUTCOMES AND MEASURES

The main outcome was the development of breast cancer in women. Whole-blood DNA methylation was measured, and methylation values were deconvoluted using the Houseman method to estimate proportions of 6 leukocyte subtypes (B cells, natural killer cells, CD8+ and CD4+ T cells, monocytes, and granulocytes). Leukocyte subtype proportions were dichotomized at their population median value, and Cox proportional hazard models were used to estimate associations with breast cancer.

RESULTS

Among 2774 non-Hispanic white women included in the analysis (mean [SD] age at enrollment, 56.6 [8.8] years), 1295 women were randomly selected from the full cohort (of whom 91 developed breast cancer) along with an additional 1479 women who developed breast cancer during follow-up (mean [SD] time to diagnosis, 3.9 [2.2] years). Circulating proportions of B cells were positively associated with later breast cancer (hazard ratio [HR], 1.17; 95% CI, 1.01-1.36; P = .04). Among women who were premenopausal at blood collection, the association between B cells and breast cancer was significant (HR, 1.38; 95% CI, 1.05-1.82; P = .02), and an inverse association for circulating proportions of monocytes was found (HR, 0.75; 95% CI, 0.57-0.99; P = .05). Among all women, associations between leukocyte subtypes and breast cancer were time dependent: higher monocyte proportions were associated with decreased near-term risk (within 1 year of blood collection, HR, 0.62; 95% CI, 0.43-0.89; P = .01), whereas higher B cell proportions were associated with increased risk 4 or more years after blood collection (HR, 1.38; 95% CI, 1.15-1.67; P = .001).

CONCLUSIONS AND RELEVANCE

Circulating leukocyte profiles may be altered before clinical diagnoses of breast cancer and may be time-dependent markers for breast cancer risk, particularly among premenopausal women.

Epigenetic mortality predictors and incidence of breast cancer

Measures derived using blood DNA methylation are increasingly under investigation as indicators of disease and mortality risk. Three existing epigenetic age measures or “epigenetic clocks” appear associated with breast cancer. Two newly-developed epigenetic mortality predictors may be related to all-cancer incidence, but associations with specific cancers have not been examined in large studies. Using HumanMethylation450 BeadChips to measure blood DNA methylation in 2,773 cancer-free women enrolled in the Sister Study, we calculated two epigenetic mortality predictors: ‘GrimAgeAccel’ and the ‘mortality score’ (MS). Using Cox proportional hazard models, neither GrimAgeAccel nor the MS were associated with overall breast cancer incidence (GrimAgeAccel hazard ratio [HR]: 1.06, 95% confidence interval [CI]: 0.98-1.14, P=0.17; MS HR: 0.99, 95% CI: 0.92-1.07, P=0.85); however, a weak, positive association was observed for GrimAgeAccel and invasive breast cancer (HR: 1.08, 95% CI: 0.99-1.17, P=0.08). Stratification of invasive cancers by menopause status at diagnoses revealed the association was predominantly observed for postmenopausal breast cancer (HR: 1.10, 95% CI: 1.01, 1.20, P=0.04). Although the MS was unrelated to breast cancer risk, we find evidence that GrimAgeAccel may be weakly associated with invasive breast cancer, particularly for women diagnosed after menopause.

Increased Cancer Prevalence in Peripartum Cardiomyopathy

Objectives

This study was designed to analyze the prevalence and potential genetic basis of cancer and heart failure in peripartum cardiomyopathy (PPCM).

Background

PPCM manifests as heart failure late in pregnancy or postpartum in women without previous heart disease.

Methods

Clinical history and cancer prevalence were evaluated in a cohort of 236 PPCM patients from Germany and Sweden. Exome sequencing assessed variants in 133 genes associated with cancer predisposition syndromes (CPS) and in 115 genes associated with dilated/hypertrophic cardiomyopathy (DCM/HCM) in 14 PPCM patients with a history of cancer, and in 6 PPCM patients without a history of cancer.

Results

The prevalence of cancer was 16-fold higher (8.9%, 21 of 236 patients) in PPCM patients compared to age-matched women (German cancer registry, Robert-Koch-Institute: 0.59%; p < 0.001). Cancer before PPCM occurred in 12 of 21 patients of whom 11 obtained cardiotoxic cancer therapies. Of those, 17% fully recovered cardiac function by 7 ± 2 months of follow-up compared to 55% of PPCM patients without cancer (p = 0.015). Cancer occurred after PPCM in 10 of 21 patients; 80% had left ventricular ejection fraction of ≥50% after cancer therapy. Whole-exome sequencing in 14 PPCM patients with cancer revealed that 43% (6 of 14 patients) carried likely pathogenic (Class IV) or pathogenic (Class V) gene variants associated with DCM/HCM in CPT2, DSP, MYH7, TTN, and/or with CPS in ATM, ERCC5, NBN, RECQL4, and SLX4. All CPS variants affected DNA damage response genes.

Conclusions

Cardiotoxic cancer therapy before PPCM is associated with delayed full recovery. The high cancer prevalence in PPCM is linked to likely pathogenic/pathogenic gene variants associated with DCM/HCM and/or CPS/DNA damage response-related cancer risk. This may warrant genetic testing and screening for heart failure in pregnant women with a cancer history and screening for cancer in PPCM patients.

Fetal microchimerism and implications for maternal health

This review paper outlines the definition, pathophysiology, and potential maternal health consequences of cellular fetal microchimerism, the maternal acquisition of intact cells of fetal origin during pregnancy. Increased rates and amounts of cellular fetal microchimerism are associated with several placental syndromes, including preeclampsia and fetal growth restriction. The discovery of cellular fetal microchimerism and methods of detection are briefly outlined, and we present the mechanisms hypothesized to govern pregnancy-related and long-term maternal health effects of cellular fetal microchimerism. Specifically, we discuss the potential implications of cellular fetal microchimerism in wound healing, autoimmunity, cancer, and possibly cardiovascular disease. Cellular fetal microchimerism represents a novel area of research on maternal and transgenerational health and disease, providing exciting opportunities for developing new disease biomarkers and precision medicine with targeted prophylaxis against long-term maternal disease.

Can postfertile life stages evolve as an anticancer mechanism?

Why a postfertile stage has evolved in females of some species has puzzled evolutionary biologists for over 50 years. We propose that existing adaptive explanations have underestimated in their formulation an important parameter operating both at the specific and the individual levels: the balance between cancer risks and cancer defenses. During their life, most multicellular organisms naturally accumulate oncogenic processes in their body. In parallel, reproduction, notably the pregnancy process in mammals, exacerbates the progression of existing tumors in females. When, for various ecological or evolutionary reasons, anticancer defenses are too weak, given cancer risk, older females could not pursue their reproduction without triggering fatal metastatic cancers, nor even maintain a normal reproductive physiology if the latter also promotes the growth of existing oncogenic processes, e.g., hormone-dependent malignancies. At least until stronger anticancer defenses are selected for in these species, females could achieve higher inclusive fitness by ceasing their reproduction and/or going through menopause (assuming that these traits are easier to select than anticancer defenses), thereby limiting the risk of premature death due to metastatic cancers. Because relatively few species experience such an evolutionary mismatch between anticancer defenses and cancer risks, the evolution of prolonged life after reproduction could also be a rare, potentially transient, anticancer adaptation in the animal kingdom.

Collagen and PAPP-A in the Etiology of Postpartum Breast Cancer

Pregnancy has a dual effect on the risk of breast cancer. On one hand, pregnancy at a young age is known to be protective. However, pregnancy is also associated with a transient increased risk of breast cancer. For women that have children after the age of 30, the risk remains higher than women who never had children for decades. Involution of the breast has been identified as a window of mammary development associated with the adverse effect of pregnancy. In this review, we summarize the current understanding of the role of involution and describe the role of collagen in this setting. We also discuss the role of a collagen-dependent protease, pappalysin-1, in postpartum breast cancer and its role in activating both insulin-like growth factor signaling and discoidin domain collagen receptor 2, DDR2. Together, these novel advances in our understanding of postpartum breast cancer open the way to targeted therapies against this aggressive breast cancer sub-type.