Postpartum Involution and Cancer: An Opportunity for Targeted Breast Cancer Prevention and Treatments?

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.

Loss of STING impairs lactogenic differentiation

Heightened energetic and nutrient demand during lactogenic differentiation of the mammary gland elicits upregulation of various stress responses to support cellular homeostasis. Here, we identify the stimulator of interferon genes (STING) as an immune supporter of the functional development of mouse mammary epithelial cells (MECs). An in vitro model of MEC differentiation revealed that STING is activated in a cGAS-independent manner to produce both type I interferons and proinflammatory cytokines in response to the accumulation of mitochondrial reactive oxygen species. Induction of STING activity was found to be dependent on the breast tumor suppressor gene single-minded 2 (SIM2). Using mouse models of lactation, we discovered that loss of STING activity results in early involution of #3 mammary glands, severely impairing lactational performance. Our data suggest that STING is required for successful functional differentiation of the mammary gland and bestows a differential lactogenic phenotype between #3 mammary glands and the traditionally explored inguinal 4|9 pair. These findings affirm unique development of mammary gland pairs that is essential to consider in future investigations into normal development and breast cancer initiation.

The Role of Breastmilk in Macrophage-Tumour Cell Interactions in Postpartum Breast Cancer

BACKGROUND

Lactation is associated with long-term reduced risk of breast cancer. However, there is a transient increased risk of breast cancer in the 5 to 10 years postpartum and this is associated with a high incidence of metastasis and mortality. Breastmilk is a physiological fluid secreted by the mammary glands intimately connected with breast cells and the microenvironment that may affect postpartum breast cancer development and progression. This study aims to investigate the effect of breastmilk on interactions between breast cancer cells and macrophages in vitro.

METHODS

Human breastmilk from healthy donors (n = 7) was pooled and incubated with breast cancer (MCF-7 and MDA-MB-231) and macrophage (RAW264.7) cell lines to assess cell proliferation, viability, migration, and expression of key genes associated with epithelial-mesenchymal transition (EMT) and macrophage phenotype. Indirect co-culture studies assessed the effect of breastmilk on interactions between breast cancer cells and macrophages.

RESULTS

Breastmilk increased the proliferation and viability of breast cancer cells, reduced EMT markers, and reduced cell migration in MDA-MB-231 cells. Breastmilk decreased mRNA expression of interleukin 1B (IL1B) and interleukin 10 (IL10) in macrophages. Reduced EMT marker expression was observed in breast cancer cells co-cultured with macrophages pre-treated with breastmilk. Macrophages co-cultured with breast cancer cells pre-treated with breastmilk exhibited increased expression of a pro-inflammatory cytokine tumor necrosis factor A (TNFA) and pro-inflammatory nitric oxide synthase 2 (NOS2), and reduced expression of cytokines IL10 and transforming growth factor B1 (TGFB1) which are associated with the alternatively-activated macrophage phenotype.

CONCLUSIONS

Breastmilk has the potential to promote breast cancer proliferation, however, it can also reduce breast cancer progression through inhibition of breast cancer cell migration and regulation of macrophage polarisation. These findings suggest that breastmilk has potential to shape the tumour microenvironment in postpartum breast cancer.

Association between breastfeeding, mammographic density, and breast cancer risk: a review

BACKGROUND

Mammographic density has been associated with breast cancer risk, and is modulated by established breast cancer risk factors, such as reproductive and hormonal history, as well as lifestyle. Recent epidemiological and biological findings underscore the recognized benefits of breastfeeding in reducing breast cancer risk, especially for aggressive subtypes. Current research exploring the association among mammographic density, breastfeeding, and breast cancer is sparse.

MAIN FINDINGS

Changes occur in the breasts during pregnancy in preparation for lactation, characterized by the proliferation of mammary gland tissues and the development of mammary alveoli. During lactation, the alveoli fill with milk, and subsequent weaning triggers the involution and remodeling of these tissues. Breastfeeding influences the breast microenvironment, potentially altering mammographic density. When breastfeeding is not initiated after birth, or is abruptly discontinued shortly after, the breast tissue undergoes forced and abrupt involution. Conversely, when breastfeeding is sustained over an extended period and concludes gradually, the breast tissue undergoes slow remodeling process known as gradual involution. Breast tissue undergoing abrupt involution displays denser stroma, altered collagen composition, heightened inflammation and proliferation, along with increased expression of estrogen receptor α (ERα) and progesterone receptor. Furthermore, elevated levels of pregnancy-associated plasma protein-A (PAPP-A) surpass those of its inhibitors during abrupt involution, enhancing insulin-like growth factor (IGF) signaling and collagen deposition. Prolactin and small molecules in breast milk may also modulate DNA methylation levels. Drawing insights from contemporary epidemiological and molecular biology studies, our review sheds light on how breastfeeding impacts mammographic density and explores its role in influencing breast cancer.

CONCLUSION

This review highlights a clear protective link between breastfeeding and reduced breast cancer risk via changes in mammographic density. Future research should investigate the effects of breastfeeding on mammographic density and breast cancer risk among various ethnic groups and elucidate the molecular mechanisms underlying these associations. Such comprehensive research will enhance our understanding and facilitate the development of targeted breast cancer prevention and treatment strategies.

Associations of SEMA7A, SEMA4D, ADAMTS10, and ADAM8 with KRAS, NRAS, BRAF, PIK3CA, and AKT Gene Mutations, Microsatellite Instability Status, and Cytokine Expression in Colorectal Cancer Tissue

Semaphorins (SEMAs), ADAM, and ADAMTS family members are implicated in various cancer progression events within the tumor microenvironment across different cancers. In this study, we aimed to evaluate the expression of SEMA7A, SEMA4D, ADAM8, and ADAMTS10 in colorectal cancer (CRC) in relation to the mutational landscape of KRAS, NRAS, BRAF, PIK3CA, and AKT genes, microsatellite instability (MSI) status, and clinicopathological features. We also examined the associations between the expression of these proteins and selected cytokines, chemokines, and growth factors, assessed using a multiplex assay. Protein concentrations were quantified using ELISA in CRC tumors and tumor-free surgical margin tissue homogenates. Gene mutations were evaluated via RT-PCR, and MSI status was determined using immunohistochemistry (IHC). GSEA and statistical analyses were performed using R Studio. We observed a significantly elevated expression of SEMA7A in BRAF-mutant CRC tumors and an overexpression of ADAM8 in KRAS 12/13-mutant tumors. The expression of ADAMTS10 was decreased in PIK3CA-mutant CRC tumors. No significant differences in the expression of the examined proteins were observed based on MSI status. The SEMA7A and SEMA4D expressions were correlated with the expression of numerous cytokines associated with various immune processes. The potential immunomodulatory functions of these molecules and their suitability as therapeutic targets require further investigation.

Immune Cell Contribution to Mammary Gland Development

Postpartum breast cancer (PPBC) is a unique subset of breast cancer, accounting for nearly half of the women diagnosed during their postpartum years. Mammary gland involution is widely regarded as being a key orchestrator in the initiation and progression of PPBC due to its unique wound-healing inflammatory signature. Here, we provide dialogue suggestive that lactation may also facilitate neoplastic development as a result of sterile inflammation. Immune cells are involved in all stages of postnatal mammary development. It has been proposed that the functions of these immune cells are partially directed by mammary epithelial cells (MECs) and the cytokines they produce. This suggests that a more niche area of exploration aimed at assessing activation of innate immune pathways within MECs could provide insight into immune cell contributions to the developing mammary gland. Immune cell contribution to pubertal development and mammary gland involution has been extensively studied; however, investigations into pregnancy and lactation remain limited. During pregnancy, the mammary gland undergoes dramatic expansion to prepare for lactation. As a result, MECs are susceptible to replicative stress. During lactation, mitochondria are pushed to capacity to fulfill the high energetic demands of producing milk. This replicative and metabolic stress, if unresolved, can elicit activation of innate immune pathways within differentiating MECs. In this review, we broadly discuss postnatal mammary development and current knowledge of immune cell contribution to each developmental stage, while also emphasizing a more unique area of study that will be beneficial in the discovery of novel therapeutic biomarkers of PPBC.

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.

Altered liver metabolism post-wean abolishes efficacy of vitamin D for breast cancer prevention in a mouse model

Young women have increased risk of vitamin D deficiency, which may increase breast cancer incidence. Here, we assessed the anti-cancer efficacy of vitamin D in mouse models of young-onset breast cancer. In never-pregnant mice, vitamin D supplementation increased serum 25(OH)D and hepatic 1,25(OH)2D3, reduced tumor size, and associated with anti-tumor immunity. These anti-tumor effects were not replicated in a mouse model of postpartum breast cancer, where hepatic metabolism of vitamin D was suppressed post-wean, which resulted in deficient serum 25(OH)D and reduced hepatic 1,25(OH)2D3. Treatment with active 1,25(OH)2D3 induced hypercalcemia exclusively in post-wean mice, highlighting metabolic imbalance post-wean. RNAseq revealed suppressed CYP450 expression postpartum. In sum, we provide evidence that vitamin D anti-tumor activity is mediated through immunomodulatory mechanisms and is ineffective in the post-wean window due to altered hepatic metabolism. These findings have implications for suppressed xenobiotic metabolism in postpartum women beyond vitamin D.

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.

Worse histopathology and prognosis in women with breast cancer diagnosed during the second trimester of pregnancy

BACKGROUND

Evidence suggests that women with breast cancer diagnosed during pregnancy (PrBC) and within 2 years of delivery (PPBC) have similar survival compared to women diagnosed not near pregnancy if adjusted for stage and subtype. To investigate whether this is true for all subtypes and for both pregnancy and post-delivery periods, we examined clinicopathologic features and survival in women with breast cancer by trimesters and 6-month post-delivery intervals.

MATERIALS AND METHODS

Women diagnosed with invasive breast cancer during 1992-2018 at ages 18-44 years were identified in the Swedish Cancer Register, with information on childbirths from the Swedish Multi-Generation Register and clinical data from Breast Cancer Quality Registers. Each woman with PrBC or PPBC was matched 1 : 2 by age and year to comparators diagnosed with breast cancer not near pregnancy. Distributions of stage, grade, and surrogate subtypes were compared. Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for breast cancer mortality were estimated using Cox regression.

RESULTS

We identified 1430 women with PrBC and PPBC (181 during pregnancy, 499 during the first and 750 during the second year after delivery). Compared to 2860 comparators, women with PrBC and PPBC in the first year after delivery had a significantly higher proportion of luminal human epidermal growth factor receptor 2 (HER2)-positive, HER2-positive and triple-negative tumours, and more advanced stage at diagnosis. After adjustment for age, year, parity, country of birth, hospital region, subtype, and stage, women diagnosed during the second trimester had a worse prognosis than matched comparators (HR 1.8, 95% CI: 1.0-3.2).

CONCLUSIONS

Women diagnosed during pregnancy or within the first year after delivery have a worse prognosis than women diagnosed not near pregnancy due to adverse tumour biology and advanced stage at diagnosis. A worse prognosis for women diagnosed during the second trimester remained after multivariable adjustment, possibly reflecting difficulties to provide optimal treatment during ongoing pregnancy.

Postpartum Breast Cancer and Survival in Women With Germline BRCA Pathogenic Variants

Importance

In young-onset breast cancer (YOBC), a diagnosis within 5 to 10 years of childbirth is associated with increased mortality. Women with germline BRCA1/2 pathogenic variants (PVs) are more likely to be diagnosed with BC at younger ages, but the impact of childbirth on mortality is unknown.

Objective

To determine whether time between most recent childbirth and BC diagnosis is associated with mortality among patients with YOBC and germline BRCA1/2 PVs.

Design, Setting, and Participants

This prospective cohort study included women with germline BRCA1/2 PVs diagnosed with stage I to III BC at age 45 years or younger between 1950 and 2021 in the United Kingdom, who were followed up until November 2021. Data were analyzed from December 3, 2021, to November 29, 2023.

Exposure

Time between most recent childbirth and subsequent BC diagnosis, with recent childbirth defined as 0 to less than 10 years, further delineated to 0 to less than 5 years and 5 to less than 10 years.

Main Outcomes and Measures

The primary outcome was all-cause mortality, censored at 20 years after YOBC diagnosis. Mortality of nulliparous women was compared with the recent post partum groups and the 10 or more years post partum group. Cox proportional hazards regression analyses were adjusted for age, tumor stage, and further stratified by tumor estrogen receptor (ER) and BRCA gene status.

Results

Among 903 women with BRCA PVs (mean [SD] age at diagnosis, 34.7 [6.1] years; mean [SD] follow-up, 10.8 [9.8] years), 419 received a BC diagnosis 0 to less than 10 years after childbirth, including 228 women diagnosed less than 5 years after childbirth and 191 women diagnosed 5 to less than 10 years after childbirth. Increased all-cause mortality was observed in women diagnosed within 5 to less than 10 years post partum (hazard ratio [HR], 1.56 [95% CI, 1.05-2.30]) compared with nulliparous women and women diagnosed 10 or more years after childbirth, suggesting a transient duration of postpartum risk. Risk of mortality was greater for women with ER-positive BC in the less than 5 years post partum group (HR, 2.35 [95% CI, 1.02-5.42]) and ER-negative BC in the 5 to less than 10 years post partum group (HR, 3.12 [95% CI, 1.22-7.97]) compared with the nulliparous group. Delineated by BRCA1 or BRCA2, mortality in the 5 to less than 10 years post partum group was significantly increased, but only for BRCA1 carriers (HR, 2.03 [95% CI, 1.15-3.58]).

Conclusions and Relevance

These findings suggest that YOBC with germline BRCA PVs was associated with increased risk for all-cause mortality if diagnosed within 10 years after last childbirth, with risk highest for ER-positive BC diagnosed less than 5 years post partum, and for ER-negative BC diagnosed 5 to less than 10 years post partum. BRCA1 carriers were at highest risk for poor prognosis when diagnosed at 5 to less than 10 years post partum. No such associations were observed for BRCA2 carriers. These results should inform genetic counseling, prevention, and treatment strategies for BRCA PV carriers.

The effect of parity, breastfeeding history, and duration on clinical and pathological characteristics of breast cancer patients

Background/aim

The study is aimed to determine the relationship between the delivery and breastfeeding history of the patients and the clinicopathological properties of breast cancer.

Materials and methods

A questionnaire was utilized for the study, which included the age of diagnosis, the number of children at the time of diagnosis, the age of the children, and the breastfeeding period of each child.

Results

The study included 828 patients. The median age at diagnosis was 47 years for parous women and 42 years for nonparous women (p < 0.001). The tumor size of the patients diagnosed within the breastfeeding period was significantly larger compared to the other patients. Estrogen and progesterone receptor positivity were lower in patients diagnosed during breastfeeding. Additionally, the mean number of positive lymph nodes, dissected lymph nodes, and positive lymph node/dissected lymph node ratio in parous and breastfed patients with a nonmetastatic disease were statistically significantly higher in multivariable analysis than those patients who were nulliparous and have not breastfed.

Conclusion

Breast cancer is seen at a later age in patients who are parous than those who have never given birth. Patients who are parous and have breastfed tend to present with a higher stage of the disease.

Clinical characteristics and pathologic complete response (pCR) rate after neoadjuvant chemotherapy in postpartum women with breast cancer

PURPOSE

Breast cancer (BC) is currently the leading cause of death in women worldwide. Studies have confirmed that pregnancy is an independent factor affecting the survival of BC patients. BC found during pregnancy, lactation, or shortly after delivery is what we used to think of as pregnancy-associated breast cancer (PABC). The current expert definition of this concept is not uniform; however, there is growing evidence that postpartum breast cancer (PPBC) differs from other types of BC in terms of both biological features and prognosis, with a slightly different focus on diagnosis and treatment. With the increase of female reproductive age population and changes in fertility policies in China, patients with PPBC are receiving increasing attention. Here, we systematically analyzed the clinicopathological characteristics and chemotherapeutic response of patients with PPBC. We retrospectively analyzed the clinicopathological data, molecular subtypes, chemotherapy regimens, and pathological complete remission (pCR) rates of 1343 patients with non-metastatic BC at Harbin Medical University Cancer Hospital from January 1, 2012 to May 31, 2023. The categorical data were compared by chi-square test and Fisher exact test using logistic regression model. Predictor variables with P < 0.05 in the univariate analysis were included in the multivariate regression analysis to investigate the relationship between different age groups and pCR.

RESULTS

A total of 714 patients were eligible for analysis in this study, and 667 patients had a history of pregnancy, 40 (5.6%) of whom were PPBC patients. When diagnosed with BC, patients with PPBC were younger, more likely to undergo breast-conserving surgery (BCS), and more likely to achieve pCR (P < 0.05). In molecular typing, human epidermal growth factor receptor 2 (HER-2)-positive and triple-negative breast cancer (TNBC) were more frequent. In the entire cohort, HER-2 expression and delivery status were independent predictors of pCR rates in BC patients after neoadjuvant chemotherapy (NAC).

CONCLUSION

Our findings suggest that postpartum status is an independent predictor of pCR attainment in BC patients. PPBC is more sensitive to chemotherapy than other patients.We need to pay more attention to this group and achieve individualized treatment, which will help us treat BC better and provide new targets and blueprints for our clinical therapy.

Early-Stage Breast Cancer Detection in Breast Milk

Breast cancer occurring during pregnancy (PrBC) and postpartum (PPBC) is usually diagnosed at more advanced stages compared with other breast cancer, worsening its prognosis. PPBC is particularly aggressive, with increased metastatic risk and mortality. Thus, effective screening methods to detect early PrBC and PPBC are needed. We report for the first time that cell-free tumor DNA (ctDNA) is present in breast milk (BM) collected from patients with breast cancer. Analysis of ctDNA from BM detects tumor variants in 87% of the cases by droplet digital PCR, while variants remain undetected in 92% of matched plasma samples. Retrospective next-generation sequencing analysis in BM ctDNA recapitulates tumor variants, with an overall clinical sensitivity of 71.4% and specificity of 100%. In two cases, ctDNA was detectable in BM collected 18 and 6 months prior to standard diagnosis. Our results open up the potential use of BM as a new source for liquid biopsy for PPBC detection.

SIGNIFICANCE

For the first time, we show that BM obtained from patients with breast cancer carries ctDNA, surpassing plasma-based liquid biopsy for detection and molecular profiling of early-stage breast cancer, even prior to diagnosis by image. See related commentary by Cunningham and Turner, p. 2125. This article is featured in Selected Articles from This Issue, p. 2109.

Characterization of human Ccser2 as a protein tracking the plus-ends of microtubules

OBJECTIVE

Microtubules, which are closely related to cell proliferation, have been the promising therapeutic target of cancer. Therefore, it is necessary to understand the intracellular control mechanisms of microtubules, the whole picture of which is still unclear though. Intracellular dynamics of microtubules are regulated by various microtubule-associated proteins, one group of which is microtubule plus-end-tracking proteins (+ TIPs), localizing to the extending tips of microtubules. Here, we report the identification and analysis of Ccser2 as a new + TIP in human breast cancer MCF-7 cells.

RESULTS

Ccser2 was found to be a member of + TIPs by microscopic observations including time-lapse imaging. The C-terminal region of Ccser2, including two SxIP motifs, was likely to be important for the tracking function. In MCF-7 cells, endogenous Ccser2 was mainly detected in the peripheral regions of microtubule fibers, suggesting that Ccser2 functions in cell projections.

The role of breastfeeding in breast cancer prevention: a literature review

Breast cancer stands as the most prevalent malignancy globally. Despite the array of treatment options, its mortality rate continues to rise annually. Thus, reevaluation of factors directly linked to breast cancer emergence is imperative, alongside the development of more effective preventive measures. Estrogen levels, profoundly tied to reproduction, play a pivotal role in breast cancer development. Speculation centers on the potential of breastfeeding to mitigate cancer risk in women. However, the precise mechanism remains elusive. Breastfeeding is a modifiable reproductive factor extensively studied. Studies highlight a direct connection between lack of breastfeeding and breast cancer emergence, potentially linked to DNA methyltransferase expression alteration, aberrant methylation levels, pregnancy-associated plasma protein-A, cellular microenvironment, and oncogenes. This study reviews recent mechanisms underlying breastfeeding's role in reducing breast cancer incidence.

Global burden of female breast cancer and its association with socioeconomic development status, 1990-2044

BACKGROUND

Breast cancer is a widespread disease in women worldwide.

AIM

We aimed to explore the global epidemiological trends of female breast cancer (FBC) between 1990 and 2044.

METHODS AND RESULTS

Disease burden, population, and socio-demographic index (SDI) data were obtained from the Global Health Data Exchange (GHDx) database. We analyzed temporal trends, age differences, risk factors, and geographic patterns of FBC disease burden globally and explored the association between age-standardized incidence rate (ASIR) of FBC and SDI. Bayesian age-period-cohort model was also performed to predict the changes in FBC incidence worldwide from 2020 to 2044. First, the global ASIR of FBC increased by 14.31% from 1990 to 2019 (95% Uncertainty Interval 4.75% to 23.98%). The death rate presented a falling trend. Second, alcohol use is the most-highlighted risk factor for FBC in some high-income regions such as Europe. A high fasting plasma glucose levels is the most prominent risk factor for FBC in Latin America and Africa. Third, the ASIR of the FBC increases with the SDI. Fourth, the incidence is expected to increase faster among women aged 35-60 years and fastest for those aged 50-54 years from 2020 to 2044. Countries with a high incidence of FBC that is expected to increase significantly include Barbados, Burkina Faso, Senegal, Monaco, Lebanon, Togo, and Uganda.

CONCLUSION

The disease burden of FBC varies worldwide; the findings suggest attaching importance to the control of middle and low-middle SDI regions. Public health as well as cancer prevention experts should pay more attention to regions and populations at an increased risk of developing FBC, focusing on their prevention and rehabilitation while conducting further epidemiological studies to investigate the risk factors of their increase.

Stabilization of E-cadherin adhesions by COX-2/GSK3β signaling is a targetable pathway in metastatic breast cancer

Metastatic progression of epithelial cancers can be associated with epithelial-mesenchymal transition (EMT) including transcriptional inhibition of E-cadherin (CDH1) expression. Recently, EM plasticity (EMP) and E-cadherin-mediated, cluster-based metastasis and treatment resistance have become more appreciated. However, the mechanisms that maintain E-cadherin expression in this context are less understood. Through studies of inflammatory breast cancer (IBC) and a 3D tumor cell "emboli" culture paradigm, we discovered that cyclooxygenase 2 (COX-2; PTGS2), a target gene of C/EBPδ (CEBPD), or its metabolite prostaglandin E2 (PGE2) promotes protein stability of E-cadherin, β-catenin, and p120 catenin through inhibition of GSK3β. The COX-2 inhibitor celecoxib downregulated E-cadherin complex proteins and caused cell death. Coexpression of E-cadherin and COX-2 was seen in breast cancer tissues from patients with poor outcome and, along with inhibitory GSK3β phosphorylation, in patient-derived xenografts (PDX) including triple negative breast cancer (TNBC).Celecoxib alone decreased E-cadherin protein expression within xenograft tumors, though CDH1 mRNA levels increased, and reduced circulating tumor cell (CTC) clusters. In combination with paclitaxel, celecoxib attenuated or regressed lung metastases. This study has uncovered a mechanism by which metastatic breast cancer cells can maintain E-cadherin-mediated cell-to-cell adhesions and cell survival, suggesting that some patients with COX-2+/E-cadherin+ breast cancer may benefit from targeting of the PGE2 signaling pathway.

Updates in the pathology of Pregnancy Associated Breast Cancer (PABC)

Pregnancy associated breast cancer (PABC) is defined as a breast cancer diagnosed during gestation, lactation or within 5 years postpartum. While the development of malignancy during pregnancy is rare, the incidence is increasing. Breast cancer is one of the most common cancers diagnosed during pregnancy, affecting up to 1 in 3000 deliveries. New understanding of the pathophysiology of PABC recently resulted in updated definitions distinguishing breast cancer diagnosed during pregnancy (PrBC) from cancer diagnosed during the postpartum period (PPBC) due to distinct biology and prognosis. Pregnancy has a dual effect on breast cancer development- both protective against cancer and promoting tumor growth. While several hypotheses have been proposed over the years to explain these effects, the most likely hypothesis for the development of PABC is the involution hypothesis, proposing that remodeling programs activated in the immediate postpartum period are similar to wound healing and inflammation that may be associated with tumor development and progression. Although PABCs reflect all subtypes of breast carcinomas, they are most commonly invasive ductal carcinomas of high tumor grade and large tumor size, with more advanced stage at presentation and higher rates of lymph node involvement. Most PABCs are hormone negative tumors (triple negative or HER2 amplified tumors) with high Ki-67 proliferation rates. Several studies have shown that PABCs have different genomic signatures than non-PABC tumors, showing increased expression of immune response mediators. Better understanding of the molecular pathways of tumor initiation and progression, along with prompt diagnosis and novel treatment protocols in the care of PrBC and PPBC are needed to improve outcomes for these young, high-risk breast cancer patients.

Fur removal promotes an earlier expression of involution-related genes in mammary gland of lactating mice

Peak lactation occurs when milk production is at its highest. The factors limiting peak lactation performance have been subject of intense debate. Milk production at peak lactation appears limited by the capacity of lactating females to dissipate body heat generated as a by-product of processing food and producing milk. As a result, manipulations that enhance capacity to dissipate body heat (such as fur removal) increase peak milk production. We investigated the potential correlates of shaving-induced increases in peak milk production in laboratory mice. By transcriptomic profiling of the mammary gland, we searched for the mechanisms underlying experimentally increased milk production and its consequences for mother-young conflict over weaning, manifested by advanced or delayed involution of mammary gland. We demonstrated that shaving-induced increases in milk production were paradoxically linked to reduced expression of some milk synthesis-related genes. Moreover, the mammary glands of shaved mice had a gene expression profile indicative of earlier involution relative to unshaved mice. Once provided with enhanced capacity to dissipate body heat, shaved mice were likely to rear their young to independence faster than unshaved mothers.

Towards defining morphologic parameters of normal parous and nulliparous breast tissues by artificial intelligence

BACKGROUND

Breast terminal duct lobular units (TDLUs), the source of most breast cancer (BC) precursors, are shaped by age-related involution, a gradual process, and postpartum involution (PPI), a dramatic inflammatory process that restores baseline microanatomy after weaning. Dysregulated PPI is implicated in the pathogenesis of postpartum BCs. We propose that assessment of TDLUs in the postpartum period may have value in risk estimation, but characteristics of these tissues in relation to epidemiological factors are incompletely described.

METHODS

Using validated Artificial Intelligence and morphometric methods, we analyzed digitized images of tissue sections of normal breast tissues stained with hematoxylin and eosin from donors ≤ 45 years from the Komen Tissue Bank (180 parous and 545 nulliparous). Metrics assessed by AI, included: TDLU count; adipose tissue fraction; mean acini count/TDLU; mean dilated acini; mean average acini area; mean "capillary" area; mean epithelial area; mean ratio of epithelial area versus intralobular stroma; mean mononuclear cell count (surrogate of immune cells); mean fat area proximate to TDLUs and TDLU area. We compared epidemiologic characteristics collected via questionnaire by parity status and race, using a Wilcoxon rank sum test or Fisher's exact test. Histologic features were compared between nulliparous and parous women (overall and by time between last birth and donation [recent birth: ≤ 5 years versus remote birth: > 5 years]) using multivariable regression models.

RESULTS

Normal breast tissues of parous women contained significantly higher TDLU counts and acini counts, more frequent dilated acini, higher mononuclear cell counts in TDLUs and smaller acini area per TDLU than nulliparas (all multivariable analyses p < 0.001). Differences in TDLU counts and average acini size persisted for > 5 years postpartum, whereas increases in immune cells were most marked ≤ 5 years of a birth. Relationships were suggestively modified by several other factors, including demographic and reproductive characteristics, ethanol consumption and breastfeeding duration.

CONCLUSIONS

Our study identified sustained expansion of TDLU numbers and reduced average acini area among parous versus nulliparous women and notable increases in immune responses within five years following childbirth. Further, we show that quantitative characteristics of normal breast samples vary with demographic features and BC risk factors.

The Risk Factors, Incidence and Prognosis of Postpartum Breast Cancer: A Nationwide Study by the SMARTSHIP Group

The term ‘pregnancy-associated breast cancer’ is no longer used as it has been consistently reported that breast cancer during pregnancy and breast cancer after delivery (postpartum breast cancer) have different characteristics and prognosis. The purpose of this study is to define postpartum breast cancer by analyzing the incidence rate, related factors, and prognosis according to the timing of breast cancer. Data from the Korean National Health Insurance Service were used to analyze 1,292,727 women aged 20-49 years who birthed their first child between 2007 and 2012. The annual incidence rate of breast cancer after delivery increased every year (7.7 per 10,000 person-years after 5 years, 19.36 per 10,000 person-years after 10 years). The risk of breast cancer was significantly higher (hazard ratio 1.15, 95% CI 1.05-1.27, P=0.0037) in women diagnosed with gestational diabetes, but that was not associated with overall survival (OS). Patients diagnosed with breast cancer within 5 years of delivery had a poorer prognosis than those diagnosed later (5-year OS, <5 years: 91.1% vs. 5-10 years: 96.0%). In multivariate analysis of OS, the hazard ratio of patients diagnosed within 5 years after delivery was twice as high as of patients diagnosed between 5 and 10 years. Women diagnosed with gestational diabetes had an increased risk of breast cancer. Breast cancer patients diagnosed within 5 years of delivery had a poorer prognosis than those diagnosed later. In this regard, careful screening for early diagnosis of high-risk patients and intensive research on new treatment strategies are needed.

Overall survival is the lowest among young women with postpartum breast cancer

BACKGROUND

Women diagnosed with breast cancer prior to age 45 years (<45y) and within the first 5 years postpartum (postpartum breast cancer, PPBC) have the greatest risk for distal metastatic recurrence.

METHODS

Pooling data from the Colorado Young Women Breast Cancer cohort and the Breast Cancer Health Disparities Study (N = 2519 cases), we examined the association of parity, age, and clinical factors with overall survival (OS) of breast cancer over 15 years of follow-up.

RESULTS

Women with PPBC diagnosed at <45y had the lowest OS (p < 0.0001), while OS of nulliparous cases diagnosed at <45y did not differ from OS of cases diagnosed at 45-65y regardless of parity status. After adjustment for study site, race/ethnicity, clinical stage, year of diagnosis and stratification for oestrogen receptor status, PPBC remained an independent factor associated with poor OS. Among cases diagnosed at <45y, nulliparous cases had 1.6 times better OS (hazard ratio (HR) = 0.61, 95%CI 0.42-0.87) compared to those with PPBC, with a more pronounced survival difference among stage I breast cancers (HR = 0.30, 95%CI 0.11-0.79). Among very young women diagnosed at age ≤35y, nulliparous cases had 2.3 times better OS (HR = 0.44, 95%CI 0.23-0.84) compared to PPBC.

CONCLUSION

Our results suggest that postpartum status is the main driver of poor prognosis in young women with breast cancer, with the strongest association in patients diagnosed at age ≤35y and in those with stage I disease.

Characteristics, treatment trends, and long-term outcomes of Japanese patients with pregnancy-associated breast cancer (PABC)

PURPOSE

To clarify the characteristics, treatment trends, and long-term outcomes of patients with pregnancy-associated breast cancer (PABC).

METHODS

PABC includes breast cancer diagnosed during pregnancy (PBC) and breast cancer diagnosed within 1 year after childbirth or during lactation (LBC). We compared clinical characteristics of 126 patients with LBC and 49 patients with PBC who underwent surgery at our hospital from 1946 to 2018. Survival was compared between patients with LBC and those with PBC in terms of breast cancer-specific disease-free survival (BC-DFS) and overall survival (OS).

RESULTS

Patients with LBC were more likely to have family history, lymph node metastasis, lymphatic invasion, and to receive chemotherapy than patients with PBC. Patients with LBC showed poorer BS-DFS and OS than patients with PBC. Among patients with LBC, those treated after 2005 were older at surgery, had a smaller tumor size, received more systemic therapy, and had a more favorable prognosis than patients treated before 2004. Family history, breast cancer within 1 year after childbirth, and surgery before 2004 as well as cStage, lymph node metastasis, and lymphatic invasion were significantly associated with poor prognosis in patients with LBC. In the multivariate analysis for BC-DFS and OS among patients with PABC, LBC vs PBC did not remain as an independent prognostic factor while cStage remained.

CONCLUSION

Patients with LBC had a poorer prognosis than those with PBC, most likely due to disease progression rather than biological characteristics. Early detection and optimization of systemic treatments are critical for improving the outcomes of patients with LBC.

Which Has a Greater Impact on the Recurrence in Young Breast Cancer Patients: Recent Childbirth or Recent Breastfeeding?

Purpose. This study explored the effects of recent childbirth and recent breastfeeding on the risk of recurrence in patients with postpartum breast cancer (PPBC). Materials and Methods. A bidirectional cohort study was conducted in the First Affiliated Hospital of Nanjing Medical University. 1013 young female breast cancer patients between May 2003 and October 2019 were enrolled. Breast cancer cases were grouped according to the time between giving birth or weaning and diagnosis. The end point of the analysis was disease-free survival (DFS). Results. Breast cancer patients diagnosed within 2 years after parturition showed more tumor characteristics that represented poor prognosis and remained at an increased risk for recurrence, even after adjusting for confounding factors (HR = 1.83, $p=0.035$ ). When the analysis was limited to patients with ER positive or histological grades I and II, they had a higher risk of recurrence. When weaning was used as the grouping node, patients diagnosed within 2 years after weaning did not show a higher risk of recurrence after adjustment, even when analysis was nearly limited to ER-positive patients. Conclusion. Recent reproductive history is an independent prognostic factor and seems to have a stronger impact on breast cancer with lower malignancy. In addition, the effect of recent childbirth on the recurrence of young breast cancer is significantly stronger than that of recent breastfeeding.

The Epidemiology of Pregnancy-Related Breast Cancers: Are We Ready to Deliver?

The dual effect of pregnancy on breast cancer risk has long been recognized. The short-term increase in breast cancer after pregnancy, particularly cancers that are more aggressive, contrasts starkly with the longer-term decrease. It remains unclear how these opposing effects of pregnancy relate to molecular subtypes of breast cancer, which impacts translation. Several methodologic challenges remain related to the study and operationalization of key constructs, which remain complicated by the correlation between age at pregnancies, overall parity, and intervals between pregnancies and cancer diagnoses. In this issue of CEBP, Vohra and colleagues address some of these major gaps as well as present novel data on the breast tissue microenvironment. The increasing incidence of invasive breast cancer in women under age 50 years requires improved clinical translation and identification of higher risk women after pregnancy. Thus, it is crucial to address the gaps in our biological understanding of pregnancy-related breast cancers. See related article by Vohra et al., p. 561.

IL-6 Cytokine Family: A Putative Target for Breast Cancer Prevention and Treatment

The IL-6 cytokine family is a group of signaling molecules with wide expression and function across vertebrates. Each member of the family signals by binding to its specific receptor and at least one molecule of gp130, which is the common transmembrane receptor subunit for the whole group. Signal transduction upon stimulation of the receptor complex results in the activation of multiple downstream cascades, among which, in mammary cells, the JAK-STAT3 pathway plays a central role. In this review, we summarize the role of the IL-6 cytokine family—specifically IL-6 itself, LIF, OSM, and IL-11—as relevant players during breast cancer progression. We have compiled evidence indicating that this group of soluble factors may be used for early and more precise breast cancer diagnosis and to design targeted therapy to treat or even prevent metastasis development, particularly to the bone. Expression profiles and possible therapeutic use of their specific receptors in the different breast cancer subtypes are also described. In addition, participation of these cytokines in pathologies of the breast linked to lactation and involution of the gland, as post-partum breast cancer and mastitis, is discussed.

Aberrant RET expression impacts on normal mammary gland post-lactation transition enhancing cancer potential

RET is a receptor tyrosine kinase with oncogenic potential in the mammary epithelium. Several receptors with oncogenic activity in the breast are known to participate in specific developmental stages. We found that RET is differentially expressed during mouse mammary gland development: RET is present in lactation and its expression dramatically decreases in involution, the period during which the lactating gland returns to a quiescent state after weaning. Based on epidemiological and pre-clinical findings, involution has been described as tumor promoting. Using the Ret/MTB doxycycline-inducible mouse transgenic system, we show that sustained expression of RET in the mammary epithelium during the post-lactation transition to involution is accompanied by alterations in tissue remodeling and an enhancement of cancer potential. Following constitutive Ret expression, we observed a significant increase in neoplastic lesions in the post-involuting versus the virgin mammary gland. Furthermore, we show that abnormal RET overexpression during lactation promotes factors that prime involution, including premature activation of Stat3 signaling and, using RNA sequencing, an acute-phase inflammatory signature. Our results demonstrate that RET overexpression negatively affects the normal post-lactation transition.

Summary: We show that RET activation stimulates Stat3 signaling in mammary epithelial cell culture and in vivo during post-lactation transition, demonstrating that the RET receptor participates in the post-lactation transition priming tumorigenesis.

Options for Endocrine-Refractory, Hormone Receptor-Positive Breast Cancer: Which Target and When?

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.

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.

Postpartum breast cancer has a distinct molecular profile that predicts poor outcomes

Young women's breast cancer (YWBC) has poor prognosis and known interactions with parity. Women diagnosed within 5-10 years of childbirth, defined as postpartum breast cancer (PPBC), have poorer prognosis compared to age, stage, and biologic subtype-matched nulliparous patients. Genomic differences that explain this poor prognosis remain unknown. In this study, using RNA expression data from clinically matched estrogen receptor positive (ER+) cases (n = 16), we observe that ER+ YWBC can be differentiated based on a postpartum or nulliparous diagnosis. The gene expression signatures of PPBC are consistent with increased cell cycle, T-cell activation and reduced estrogen receptor and TP53 signaling. When applied to a large YWBC cohort, these signatures for ER+ PPBC associate with significantly reduced 15-year survival rates in high compared to low expressing cases. Cumulatively these results provide evidence that PPBC is a unique entity within YWBC with poor prognostic phenotypes.

Clinical outcomes and prognostic biomarkers among pregnant, post-partum and nulliparous women with breast cancer: a prospective cohort study

PURPOSE

To compare clinical-pathologic characteristics and outcomes of pregnancy-associated, post-partum (PP) and nulliparous (NP) breast cancer (BC) patients and explore mediators of the poor prognosis associated with post-partum BC.

METHODS

A prospective database of 233 women ≤ 40 years of age diagnosed with BC between February 2008 and January 2015 was analysed. Clinical-pathologic characteristics and outcomes among pregnant, PP and NP patients were compared using chi-square or Kruskal-Wallis tests. The Kaplan-Meier method was used to estimate disease-free survival (DFS), distant DFS and overall survival (OS). Survival curves were compared using the log-rank test. Univariable Cox proportional hazards regression models were used to evaluate factors that were potentially prognostic for the clinical outcomes of interest; a multivariable Cox model was constructed using a forward stepwise selection process. Androgen receptor (AR), GATA3, PDL1 status and the presence/absence of tumour-infiltrating lymphocytes (TILs) were assessed when possible. Pre-treatment neutrophil and lymphocyte counts were abstracted retrospectively. Statistical significance was defined as a p value ≤ 0.05.

RESULTS

Women ≤ 2 years PP had a numerically higher incidence of lymph node-positive and high-grade disease and were significantly more likely to have estrogen receptor-negative BC compared to NP controls. With a median follow-up of 7.2 years, increasingly poor outcomes were observed among NP (longest OS), > 2 years PP, ≤ 2 years PP and pregnant (shortest OS) patients, but these differences were not statistically significant. The ≤ 2 years PP group had significantly lower AR expression, a strong trend toward higher PDL1 expression and a higher expression of stromal TILs compared to NP women.

CONCLUSIONS

PPBC patients had numerically lower DFS and OS compared to NP controls. Higher PDL1 and stromal TILs in PPBC suggest that adjuvant immunotherapy may be effective in the post-partum BC subgroup.

Anoikis resistance in mammary epithelial cells is mediated by semaphorin 7a

Semaphorin-7a (SEMA7A), best known as a neuroimmune molecule, plays a diverse role in many cellular processes and pathologies. Here, we show that SEMA7A promotes anoikis resistance in cultured mammary epithelial cells through integrins and activation of pro-survival kinase AKT, which led us to investigate a role for SEMA7A during postpartum mammary gland involution-a normal developmental process where cells die by anoikis. Our results reveal that SEMA7A is expressed on live mammary epithelial cells during involution, that SEMA7A expression is primarily observed in α6-integrin expressing cells, and that luminal progenitor cells, specifically, are decreased in mammary glands of SEMA7A-/- mice during involution. We further identify a SEMA7A-α6/β1-integrin dependent mechanism of mammosphere formation and chemoresistance in mammary epithelial cells and suggest that this mechanism is relevant for recurrence in breast cancer patients.

Best Practices for Spatial Profiling for Breast Cancer Research with the GeoMx® Digital Spatial Profiler

Breast cancer is a heterogenous disease with variability in tumor cells and in the surrounding tumor microenvironment (TME). Understanding the molecular diversity in breast cancer is critical for improving prediction of therapeutic response and prognostication. High-plex spatial profiling of tumors enables characterization of heterogeneity in the breast TME, which can holistically illuminate the biology of tumor growth, dissemination and, ultimately, response to therapy. The GeoMx Digital Spatial Profiler (DSP) enables researchers to spatially resolve and quantify proteins and RNA transcripts from tissue sections. The platform is compatible with both formalin-fixed paraffin-embedded and frozen tissues. RNA profiling was developed at the whole transcriptome level for human and mouse samples and protein profiling of 100-plex for human samples. Tissue can be optically segmented for analysis of regions of interest or cell populations to study biology-directed tissue characterization. The GeoMx Breast Cancer Consortium (GBCC) is composed of breast cancer researchers who are developing innovative approaches for spatial profiling to accelerate biomarker discovery. Here, the GBCC presents best practices for GeoMx profiling to promote the collection of high-quality data, optimization of data analysis and integration of datasets to advance collaboration and meta-analyses. Although the capabilities of the platform are presented in the context of breast cancer research, they can be generalized to a variety of other tumor types that are characterized by high heterogeneity.

A comparative study of bilateral and unilateral early sucking within 2 hours of delivery on lactation

OBJECTIVE

This study explored and analyzed the effects of bilateral and unilateral early sucking within 2 h after delivery on lactation.

METHODS

From August 2019 to August 2020, 392 primiparas with full-term, singleton, natural delivery, and normal breast conditions were submitted to the Obstetrics Department of our hospital and were enrolled as the research subjects. The subjects were randomly divided into an experimental group and a control group, with 196 in each group. Both groups implemented early sucking with the assistance of a midwife within 2 h after delivery. The experimental group conducted bilateral breast sucking and the control group received unilateral sucking. The onset time of colostrum, the lactation volume, and the prolactin levels at 6 h, 24 h, 48 h, and 72 h after delivery, including neonatal urination and incidence of complications were compared between the two groups.

RESULTS

The onset time of colostrum in the experimental group was much earlier than that in the control group with a statistically significant difference (P<0.05). The postpartum filling time of the experimental group was shorter than that of the control group, with a statistically significant difference (P<0.05). There was a statistically insignificant difference in the distribution of lactation yield between the two groups at 6 h of postpartum (P>0.05). The lactation yield distribution in the experimental group at 24 h, 48 h, and 72 h was critically superior to that in control group, with statistically significant difference (P<0.05). The degree of prolactin in the experimental group was higher than that in the control group (P<0.05). There was no significant difference in urination frequency and the incidence of complications between the two groups of neonates at 24 h, 48 h, and 72 h (P>0.05).

CONCLUSION

The effect of bilateral early lactation within 2 h after delivery is superior to that of unilateral early lactation, which is worthy of clinical application.

Breast cancer diagnosed in the post-weaning period is indicative for a poor outcome

BACKGROUND

In young women, a breast cancer diagnosis after childbirth increases the risk for metastasis and death. Studies in rodents suggest that post-weaning mammary gland involution contributes to the poor prognosis of postpartum breast cancers. However, this association has not been investigated in humans, mainly because of missing information on the patient's lactation status at diagnosis.

PATIENTS AND METHODS

Clinicopathological data of 1180 young women with primary invasive breast cancer, diagnosed within 2 years postpartum (PP-BC), during pregnancy (Pr-BC), or nulliparous (NP-BC), were collected. For PP-BC patients, breastfeeding history was retrieved to differentiate breast cancers identified during lactation (PP-BC_DL) from those diagnosed post-weaning (PP-BC_PW). Differences in prognostic parameters, first site of distant metastasis, and risks for metastasis and death were determined between patient groups.

RESULTS

Cox proportional hazard models pointed to a twofold increased the risk of metastasis and death in PP-BC_PW patients compared with PP-BC_DL (hazard ratio [HR] 2.1 [P_DRS = 0.021] and 2.9 [P_OS = 0.004]), Pr-BC (HR 2.1 [P_DRS<0.001] and 2.3 [P_OS<0.001]) and NP-BC (HR 2.1 [P_DRS<0.001] and 2.0 [P_OS<0.001]) patients. Prognosis was poorest for PP-BC_PW patients who did not breastfeed or only for ≤ 3 months before diagnosis. This could not fully be attributed to differences in standard prognostic characteristics. In addition, PP-BC_PW tumours showed a 3- to 8-fold increased risk to metastasise to the liver, yet this did not correlate with the poor outcome of this patient cohort.

CONCLUSIONS

Breast cancer diagnosed shortly after weaning specifically adds to the poor prognosis in women diagnosed with PP-BC. Apart from the importance of an increased awareness, these data show that detailed lactation data need to be registered when breast cancer outcome in young women is investigated.

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.

Using Organ Specific and Circulatory Biofluids to Screen Individuals at High Risk for Breast Cancer Presents Unique Challenges and Opportunities

Intraductal assessment of the breast holds the potential to provide useful information regarding breast cancer risk assessment, early diagnosis, and/or response to therapy. Intraductal assessment can be through imaging (ductography), direct visualization (mammary ductoscopy), or evaluation of the intraductal fluid collected. The most common nonradiologic approaches to intraductal assessment that provide intraductal fluid for evaluation include breast nipple aspiration fluid (NAF), spontaneous nipple discharge (SND), mammary ductoscopy, and ductal lavage. The first two approaches are entirely noninvasive while the latter are considered minimally invasive. Nipple aspiration is performed both on women with and without evidence of possible disease in the breast. On the other hand, unilateral SND suggests the presence of a lesion in the incident breast, while bilateral SND is most often physiologic. The focus of the report by Patuleia and colleagues is on challenges, lessons learned, and recommended solutions in the identification of women with increased breast cancer risk who are more likely to develop in situ or invasive breast cancer based on sequential collection and subsequent analysis of biofluids (NAF and serum). The lessons learned that are discussed can also be applied to other types of biofluid studies for cancer early detection and response to treatment.See related article by Patuleia et al., p. 441.

Incidence of Pregnancy-Associated Cancer in Two Canadian Provinces: A Population-Based Study

Pregnancy-associated cancer—that is diagnosed in pregnancy or within 365 days after delivery—is increasingly common as cancer therapy evolves and survivorship increases. This study assessed the incidence and temporal trends of pregnancy-associated cancer in Alberta and Ontario—together accounting for 50% of Canada’s entire population. Linked data from the two provincial cancer registries and health administrative data were used to ascertain new diagnoses of cancer, livebirths, stillbirths and induced abortions among women aged 18–50 years, from 2003 to 2015. The annual crude incidence rate (IR) was calculated as the number of women with a pregnancy-associated cancer per 100,000 deliveries. A nonparametric test for trend assessed for any temporal trends. In Alberta, the crude IR of pregnancy-associated cancer was 156.2 per 100,000 deliveries (95% CI 145.8–166.7), and in Ontario, the IR was 149.4 per 100,000 deliveries (95% CI 143.3–155.4). While no statistically significant temporal trend in the IR of pregnancy-associated cancer was seen in Alberta, there was a rise in Ontario (p = 0.01). Pregnancy-associated cancer is common enough to warrant more detailed research on maternal, pregnancy and child outcomes, especially as cancer therapies continue to evolve.

Postpartum breast cancer: mechanisms underlying its worse prognosis, treatment implications, and fertility preservation

Breast cancers that occur in young women up to 5 to 10 years' postpartum are associated with an increased risk for metastasis and death compared with breast cancers diagnosed in young, premenopausal women during or outside pregnancy. Given the trend to delay childbearing, this frequency is expected to increase. The (immuno)biology of postpartum breast cancer is poorly understood and, hence, it is unknown why postpartum breast cancer has an enhanced risk for metastasis or how it should be effectively targeted for improved survival. The poorer prognosis of women diagnosed within 10 years of a completed pregnancy is most often contributed to the effects of mammary gland involution. We will discuss the most recent data and mechanistic insights of the most important processes associated with involution and their role in the adverse effects of a postpartum diagnosis. We will also look into the effect of lactation on breast cancer outcome after diagnosis. In addition, we will discuss the available treatment strategies that are currently being used to treat postpartum breast cancer, keeping in mind the importance of fertility preservation in this group of young women. These additional insights might offer potential therapeutic options for the improved treatment of women with this specific condition.

Maternal survival of patients with pregnancy-associated cancers in Taiwan - A national population-based study

Pregnancy-associated cancer (PAC), defined as cancers diagnosed during pregnancy or the first year after delivery, affects one to two in every 1000 pregnancies. Although PAC is expected to be a growing issue, information about PAC in the Asian population is still scarce. Women with cancer diagnosed at the age of 16-49 years between 2001 and 2015 were selected from the Taiwan Cancer Registry and linked with the National Birth Reporting Database to identify PAC patients. We compared the overall survival of patients with PAC to patients without pregnancy. Among 126,646 female cancer patients of childbearing age, 512 were diagnosed during pregnancy, and 2151 during the first postpartum year. Breast cancer was the most common PAC (N = 755, 28%). Compared with patients without pregnancy in the control group, patients with cancers diagnosed during pregnancy and the first postpartum year generally had more advanced stages (odds ratio 1.35 and 1.36, 95% confidence interval [CI] 1.02-1.77 and 1.18-1.57, respectively). For all cancer types combined and controlled for the stage, age, and year of diagnosis, patients with PAC had similar overall survival with those in the control group, with a hazard ratio (HR) of 1.07 (95% CI 0.80-1.41) for the pregnancy group and HR 1.02 (95% CI 0.88-1.18) for the postpartum group. The diagnosis of breast cancer during the first postpartum year was linked with shorter survival (HR 1.34, 95% CI 1.05-1.72). In contrast, patients with postpartum lymphoma (HR 0.11, 95% CI 0.02-0.79) and cervical cancer (HR 0.40, 95% CI 0.20-0.82) had better prognosis. In general, the diagnosis of cancer during pregnancy or the first postpartum year does not affect the survival of patients with most cancer types. Exceptions include the worse prognosis of postpartum breast cancer and the better outcome of postpartum lymphoma and cervical cancer.

Breast Cancer Cell Detection and Characterization from Breast Milk-Derived Cells

Radiologic techniques remain the main method for early detection for breast cancer and are critical to achieve a favorable outcome from cancer. However, more sensitive detection methods to complement radiologic techniques are needed to enhance early detection and treatment strategies. Using our recently established culturing method that allows propagation of normal and cancerous breast epithelial cells of luminal origin, flow cytometry characterization, and genomic sequencing, we show that cancer cells can be detected in breast milk. Cells derived from milk from the breast with cancer were enriched for CD49f⁺/EpCAM^-, CD44⁺/CD24^-, and CD271⁺ cancer stem-like cells (CSC). These CSCs carried mutations within the cytoplasmic retention domain of HDAC6, stop/gain insertion in MORF4L1, and deletion mutations within SWI/SNF complex component SMARCC2. CSCs were sensitive to HDAC6 inhibitors, BET bromodomain inhibitors, and EZH2 inhibitors, as mutations in SWI/SNF complex components are known to increase sensitivity to these drugs. Among cells derived from breast milk of additional ten women not known to have breast cancer, two of them contained cells that were enriched for the CSC phenotype and carried mutations in NF1 or KMT2D, which are frequently mutated in breast cancer. Breast milk-derived cells with NF1 mutations also carried copy-number variations in CDKN2C, PTEN, and REL genes. The approach described here may enable rapid cancer cell characterization including driver mutation detection and therapeutic screening for pregnancy/postpartum breast cancers. Furthermore, this method can be developed as a surveillance or early detection tool for women at high risk for developing breast cancer. SIGNIFICANCE: These findings describe how a simple method for characterization of cancer cells in pregnancy and postpartum breast cancer can be exploited as a surveillance tool for women at risk of developing breast cancer.

The Multi-Faced Role of PAPP-A in Post-Partum Breast Cancer: IGF-Signaling is Only the Beginning

Insulin-like growth factor (IGF) signaling and control of local bioavailability of free IGF by the IGF binding proteins (IGFBP) are important regulators of both mammary development and breast cancer. A recent genome-wide association study (GWAS) identified small nucleotide polymorphisms that reduce the expression of IGFBP-5 as a risk factor of developing breast cancer. This observation suggests that genetic alterations leading to a decreased level of IGFBP-5 may also contribute to breast cancer. In the current review, we focus on Pregnancy-Associated Plasma Protein A (PAPP-A), a protease involved in the degradation of IGFBP-5. PAPP-A is overexpressed in the majority of breast cancers but its role in cancer has only begun to be explored. More specifically, this review aims at highlighting the role of post-partum involution in the oncogenic function of PAPP-A. Notably, we summarize recent studies indicating that PAPP-A plays a role not only in the degradation of IGFBP-5 but also in the deposition of collagen and activation of the collagen receptor discoidin 2 (DDR2) during post-partum involution. Finally, considering the immunosuppressive microenvironment of post-partum involution, we also discuss the unexpected finding made in Ewing Sarcoma that PAPP-A plays a role in immune evasion. While the immunosuppressive role of PAPP-A in breast cancer remains to be determined, collectively these studies highlight the multifaced role of PAPP-A in cancer that extends well beyond its effect on IGF-signaling.

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.