Mathematical Modeling Links Pregnancy-Associated Changes and Breast Cancer Risk

Cabergoline as a Novel Strategy for Post-Pregnancy Breast Cancer Prevention in Mice and Human

Post-pregnancy breast cancer often carries a poor prognosis, posing a major clinical challenge. The increasing trend of later-life pregnancies exacerbates this risk, highlighting the need for effective chemoprevention strategies. Current options, limited to selective estrogen receptor modulators, aromatase inhibitors, or surgical procedures, offer limited efficacy and considerable side effects. Here, we report that cabergoline, a dopaminergic agonist, reduces the risk of breast cancer post-pregnancy in a Brca1/P53-deficient mouse model, with implications for human breast cancer prevention. We show that a single dose of cabergoline administered post-pregnancy significantly delayed the onset and reduced the incidence of breast cancer in Brca1/P53-deficient mice. Histological analysis revealed a notable acceleration in post-lactational involution over the short term, characterized by increased apoptosis and altered gene expression related to ion transport. Over the long term, histological changes in the mammary gland included a reduction in the ductal component, decreased epithelial proliferation, and a lower presence of recombinant Brca1/P53 target cells, which are precursors of tumors. These changes serve as indicators of reduced breast cancer susceptibility. Additionally, RNA sequencing identified gene expression alterations associated with decreased proliferation and mammary gland branching. Our findings highlight a mechanism wherein cabergoline enhances the protective effect of pregnancy against breast cancer by potentiating postlactational involution. Notably, a retrospective cohort study in women demonstrated a markedly lower incidence of post-pregnancy breast cancer in those treated with cabergoline compared to a control group. Our work underscores the importance of enhancing postlactational involution as a strategy for breast cancer prevention, and identifies cabergoline as a promising, low-risk option in breast cancer chemoprevention. This strategy has the potential to revolutionize breast cancer prevention approaches, particularly for women at increased risk due to genetic factors or delayed childbirth, and has wider implications beyond hereditary breast cancer cases.

Breast cancer prevention by short-term inhibition of TGFβ signaling

Cancer prevention has a profound impact on cancer-associated mortality and morbidity. We previously identified TGFβ signaling as a candidate regulator of mammary epithelial cells associated with breast cancer risk. Here, we show that short-term TGFBR inhibitor (TGFBRi) treatment of peripubertal ACI inbred and Sprague Dawley outbred rats induces lasting changes and prevents estrogen- and carcinogen-induced mammary tumors, respectively. We identify TGFBRi-responsive cell populations by single cell RNA-sequencing, including a unique epithelial subpopulation designated secretory basal cells (SBCs) with progenitor features. We detect SBCs in normal human breast tissues and find them to be associated with breast cancer risk. Interactome analysis identifies SBCs as the most interactive cell population and the main source of insulin-IGF signaling. Accordingly, inhibition of TGFBR and IGF1R decrease proliferation of organoid cultures. Our results reveal a critical role for TGFβ in regulating mammary epithelial cells relevant to breast cancer and serve as a proof-of-principle cancer prevention strategy.

Cancer's second genome: Microbial cancer diagnostics and redefining clonal evolution as a multispecies process: Humans and their tumors are not aseptic, and the multispecies nature of cancer modulates clinical care and clonal evolution: Humans and their tumors are not aseptic, and the multispecies nature of cancer modulates clinical care and clonal evolution

The presence and role of microbes in human cancers has come full circle in the last century. Tumors are no longer considered aseptic, but implications for cancer biology and oncology remain underappreciated. Opportunities to identify and build translational diagnostics, prognostics, and therapeutics that exploit cancer's second genome-the metagenome-are manifold, but require careful consideration of microbial experimental idiosyncrasies that are distinct from host-centric methods. Furthermore, the discoveries of intracellular and intra-metastatic cancer bacteria necessitate fundamental changes in describing clonal evolution and selection, reflecting bidirectional interactions with non-human residents. Reconsidering cancer clonality as a multispecies process similarly holds key implications for understanding metastasis and prognosing therapeutic resistance while providing rational guidance for the next generation of bacterial cancer therapies. Guided by these new findings and challenges, this Review describes opportunities to exploit cancer's metagenome in oncology and proposes an evolutionary framework as a first step towards modeling multispecies cancer clonality. Also see the video abstract here: https://youtu.be/-WDtIRJYZSs.

Predicting the likelihood of recurrence of pregnancy-associated breast cancer: Nomogram based on analysis of the French cancer network: Cancer Associé à La Grossesse

OBJECTIVE

Pregnancy associated breast cancer (PABC) are defined as breast cancer diagnosed during pregnancy and during the year following delivery. The prediction of poor prognosis events (PPE) such as recurrence is a major medical challenge of management for women with PABC. The aim of this study was to build a nomogram based on selected clinical and histological variables to predict recurrence.

STUDY DESIGN

This retrospective study included 96 patients with PABC from January 2002 to January 2018. A multivariate Cox analysis of selected risk factors was performed and a nomogram to predict recurrence was built. The nomogram was internally validated.

RESULTS

The overall recurrence rate was 22% (21/95) and the 3-years recurrence rate was 13% (12/95). Age at diagnosis, histological type, immuno-histological class, tumor stage (TNM), node stage (TNM) were associated with PPE in univariate analysis, and were included in the final Cox model to develop the nomogram. The predictive model had a concordance index of 0.83 (95% Confidence Interval (CI), 0.81-0.85) and 0.78 (95% CI, 0.76-0.80) before and after the 200 repetitions of bootstrap sample corrections, respectively, and showed a good calibration.

CONCLUSION

Our results support the use of the present nomogram based on 5 clinical and pathological characteristics to predict PPE in PABC with a high concordance. External validation is required to recommend this nomogram in routine practice.

Pregnancy and Breast Cancer: Pathways to Understand Risk and Prevention

Several studies have made strong efforts to understand how age and parity modulate the risk of breast cancer. A holistic understanding of the dynamic regulation of the morphological, cellular, and molecular milieu of the mammary gland offers insights into the drivers of breast cancer development as well as into potential prophylactic interventions, the latter being a longstanding ambition of the research and clinical community aspiring to eradicate the disease. In this review we discuss mechanisms that react to pregnancy signals, and we delineate the nuances of pregnancy-associated dynamism that contribute towards either breast cancer development or prevention. Further definition of the molecular basis of parity and breast cancer risk may allow the elaboration of tools to predict and survey those who are at risk of breast cancer development.

Differential effect of parity on rat mammary carcinogenesis after pre- or post-pubertal exposure to radiation

Radiation exposure during the peri-pubertal period is a proven risk factor for breast cancer, whereas parity is an established protective factor. The present study investigated whether parity imposes differential protective effects against radiation-induced rat mammary carcinoma depending on the age at exposure. Pre- and post-pubertal female rats, irradiated or left unirradiated, were mated and allowed to nurse until weaning or left unmated. Appearance of mammary tumors was monitored, and serum concentrations of estradiol and progesterone were measured following weaning. Carcinomas were evaluated by immunohistochemistry for estrogen receptor, progesterone receptor, and the cell proliferation marker Ki-67. Parity reduced the risk of carcinoma in unirradiated and pre-pubertally irradiated rats but not post-pubertally irradiated rats. Although radiation exposure increased serum progesterone level, parity after pre-pubertal exposure significantly decreased the elevated progesterone to a normal level, reflecting a protective effect. Moreover, parity significantly decreased the proportion of hormone receptor-positive carcinomas after pre-pubertal exposure. Parity was also related to the observed positive association between progesterone receptor and Ki-67 indices in cancer tissue, implying progesterone receptor-dependent cell proliferation. Thus, parity protects against radiation-induced rat mammary carcinogenesis depending on the age at exposure; the mechanisms may involve changes in hormone levels and cancer tissue.

Propensity score to evaluate prognosis in pregnancy-associated breast cancer: Analysis from a French cancer network

PURPOSE

To compare the prognosis of pregnancy associated breast cancer occurring during pregnancy (BCP) to non-pregnancy associated breast cancers (non-BCP) in young women managed at a national expert center.

METHODS

Retrospective cohort study of a prospective database using propensity score matching (PSM) analysis with known prognostic factors.

RESULTS

We analyzed data of 49 patients with BCP and 104 with non-BCP diagnosed between 2002 and 2017 at Tenon University Hospital (Paris, France). The BCP tumors were often locally advanced (lymph node metastases in 59%), of high grade (55%) and highly proliferative (67% with Ki67 ≥ 20%). After PSM, breast cancer-free survival (p = 0.45) and breast cancer specific survival (p = 0.81) were similar in the two groups. The recurrence rate was 12% vs 18% (p = 0.45) and the death rate was 6% vs 8% (p = 0.74) for the BCP and non-BCP groups, respectively. No difference in recurrence type was observed between the groups (p = 0.60).

CONCLUSIONS

After PSM for known prognostic factors, the prognosis of BCP patients did not differ from that of young patients with non-BCP.