Progesterone from ovulatory menstrual cycles is an important cause of breast cancer

Age-Stratified Assessment of the Impact of Breast Cancer Knowledge on the Lifestyle and Dietary Patterns Among Nigerian Females

PURPOSE

Breast cancer (BC) is a major cause of cancer-related mortality in Nigeria, which is exacerbated by a lack of understanding of how knowledge of BC risk factors influences the lifestyle and dietary patterns of Nigerians across age groups. This study evaluated the influence of knowledge of BC risks on lifestyle and dietary patterns across age groups, aiming to inform early management, prevention, and survival rates.

METHODS

A cross-sectional survey was conducted in Ota, Ado-odo, Ogun State, Nigeria, involving participants from six educational institutions. The study assessed knowledge of BC risks factors and lifestyle/dietary habits using questionnaires. Results were analyzed using Epi Info software and SPSS version 20.

RESULTS

The participants' age ranged from 13 to 60 years, with a mean of 21 years. The age categories of the participants were 75.24% adolescents (13-19), 18.68% young adults (20-40), and 6.08% middle-aged (41-60). Middle-aged individuals had the least knowledge about smoking (7.58%), alcohol (26.09%), antibiotics (7.25%), and red meat/smoked foods (20.09%), which translated into their poor dietary/lifestyle patterns. Young adults showed profound physical inactivity (71.00%), while adolescents consumed more carbonated drinks (71.53%), which corresponded to lack of knowledge about the effects of physical inactivity (10.85%) and consumption of carbonated drinks (13.70%) on BC risk.

CONCLUSION

The study found that understanding BC risk factors directly affects lifestyle and dietary patterns. Age groups with higher knowledge had better lifestyle/dietary patterns. This highlights the need for a tailored intervention on lifestyle and dietary education across all age groups, especially the middle-aged, so as to inform a deliberate adjustment in lifestyle and dietary habits, which play crucial roles in BC incidence, survival, and prevention.

Transcriptomic Profile of Breast Tissue of Premenopausal Women Following Treatment with Progesterone Receptor Modulator: Secondary Outcomes of a Randomized Controlled Trial

Progesterone receptor antagonism is gaining attention due to progesterone's recognized role as a major mitogen in breast tissue. Limited but promising data suggest the potential efficacy of antiprogestins in breast cancer prevention. The present study presents secondary outcomes from a randomized controlled trial and examines changes in breast mRNA expression following mifepristone treatment in healthy premenopausal women. We analyzed 32 paired breast biopsies from 16 women at baseline and after two months of mifepristone treatment. In total, 27 differentially expressed genes were identified, with enriched biological functions related to extracellular matrix remodeling. Notably, the altered gene signature induced by mifepristone in vivo was rather similar to the in vitro signature. Furthermore, this gene expression signature was linked to breast carcinogenesis and notably linked with progesterone receptor expression status in breast cancer, as validated in The Cancer Genome Atlas dataset using the R2 platform. The present study is the first to explore the breast transcriptome following mifepristone treatment in normal breast tissue in vivo, enhancing the understanding of progesterone receptor antagonism and its potential protective effect against breast cancer.

Rat Models of Hormone Receptor-Positive Breast Cancer

Hormone receptor-positive (HR+) breast cancer (BC) is the most common type of breast cancer among women worldwide, accounting for 70-80% of all invasive cases. Patients with HR+ BC are commonly treated with endocrine therapy, but intrinsic or acquired resistance is a frequent problem, making HR+ BC a focal point of intense research. Despite this, the malignancy still lacks adequate in vitro and in vivo models for the study of its initiation and progression as well as response and resistance to endocrine therapy. No mouse models that fully mimic the human disease are available, however rat mammary tumor models pose a promising alternative to overcome this limitation. Compared to mice, rats are more similar to humans in terms of mammary gland architecture, ductal origin of neoplastic lesions and hormone dependency status. Moreover, rats can develop spontaneous or induced mammary tumors that resemble human HR+ BC. To date, six different types of rat models of HR+ BC have been established. These include the spontaneous, carcinogen-induced, transplantation, hormone-induced, radiation-induced and genetically engineered rat mammary tumor models. Each model has distinct advantages, disadvantages and utility for studying HR+ BC. This review provides a comprehensive overview of all published models to date.

Breastfeeding's protective role in alleviating breast cancer burden: a comprehensive review

Breastfeeding, an essential aspect of infant care, has garnered recognition beyond its immediate health benefits, revealing a profound and lasting impact on women's health. Emerging research has unveiled a compelling relationship between breastfeeding and its enduring role in reducing the risk of ovarian cancer. This narrative review aims to comprehensively examine the lifelong impact of breastfeeding on ovarian cancer prevention, transcending infancy and delving into the mechanisms and implications for women's health. Epidemiological evidence consistently demonstrates an inverse association between breastfeeding and the risk of ovarian cancer. Prolonged durations of breastfeeding correlate with a significant reduction in the likelihood of developing ovarian malignancies, underscoring the protective influence of sustained lactation. The mechanisms underlying breastfeeding's impact on ovarian cancer prevention involve hormonal modulation and cellular changes. Breastfeeding contributes to reduced ovulatory cycles and oestrogen exposure, mitigating hormonal influences linked to ovarian cancer development. Moreover, the cellular alterations induced by breastfeeding within the ovarian microenvironment create an environment less conducive to malignant transformations. In conclusion, this paper consolidates evidence demonstrating breastfeeding's enduring impact on reducing ovarian cancer risk. It emphasizes the need for continued research, supportive interventions, and societal engagement to promote breastfeeding practices. Embracing breastfeeding not only provides immediate health benefits but also represents a formidable strategy in lifelong ovarian cancer prevention, offering a promising pathway towards enhanced women's health and well-being.

Risk factors for breast cancer subtypes by race and ethnicity: A scoping review of the literature

Background

Breast cancer is comprised of distinct molecular subtypes. Studies have reported differences in risk factor associations with breast cancer subtypes, especially by tumor estrogen receptor (ER) status, but their consistency across racial and ethnic populations has not been comprehensively evaluated.

Methods

We conducted a qualitative, scoping literature review using the Preferred Reporting Items for Systematic Reviews and Meta-analysis, extension for Scoping Reviews to investigate consistencies in associations between 18 breast cancer risk factors (reproductive, anthropometric, lifestyle, and medical history) and risk of ER-defined subtypes in women who self-identify as Asian, Black or African American, Hispanic or Latina, or White. We reviewed publications between January 1, 1990 and July 1, 2022. Etiologic heterogeneity evidence (convincing, suggestive, none, or inconclusive) was determined by expert consensus.

Results

Publications per risk factor ranged from 14 (benign breast disease history) to 66 (parity). Publications were most abundant for White women, followed by Asian, Black or African American, and Hispanic or Latina women. Etiologic heterogeneity evidence was strongest for parity, followed by age at first birth, post-menopausal BMI, oral contraceptive use, and estrogen-only and combined menopausal hormone therapy. Evidence was limited for other risk factors. Findings were consistent across racial and ethnic groups, although the strength of evidence varied.

Conclusion

The literature supports etiologic heterogeneity by ER for some established risk factors that are consistent across race and ethnicity groups. However, in non-White populations evidence is limited. Larger, more comparable data in diverse populations is needed to better characterize breast cancer etiologic heterogeneity.

Oncogenic BRCA1,2 Mutations in the Human Lineage-A By-Product of Sexual Selection?

In this review, we discuss the long-known problem of tissue-specific carcinogenesis in BRCA1 and BRCA2 mutation carriers: while the genes are expressed ubiquitously, increased cancer risk is observed mostly in the breast and ovaries, and to a much lesser extent, in some other tissues such as the prostate or pancreas. We reevaluate hypotheses on the evolutionary origin of these mutations in humans. Also, we align together the reports that at least some great apes have much lower risks of epithelial cancers in general and breast cancer in particular with the fact that humans have more voluminous breast tissue as compared to their closest extant relatives, particularly chimpanzees and bonobos. We conjecture that this disparity may be a consequence of sexual selection, augmented via selection for enhanced lactation. Further, we argue that there is an organ-specific enigma similar to the Peto paradox: breast cancer risk in humans is only minimally correlated with breast size. These considerations lead to the hypothesis that, along with the evolutionary development of larger breasts in humans, additional changes have played a balancing role in suppressing breast cancer. These yet-to-be-discovered mechanisms, while purely speculative, may be valuable to understanding human breast cancer, though they may not be exclusive to the mammary gland epithelial cells. Combining these themes, we review some anti-carcinogenesis preventive strategies and prospects of new interventions against breast cancer.

Lack of evidence that progesterone in ovulatory cycles causes breast cancer

A recent Perspective article asserted that progesterone secretion during ovulatory cycles is the cause of breast cancer. However, we challenge most of the evidence developed in this publication. First, there is a lack of evidence that progesterone is mutagenic for breast cells. Cause of a cancer should mean initiation by mutation, as opposed to promotion. Second, subclinical ovulatory disturbances occur rather frequently in normal-length menstrual cycles. Third, the authors attribute a potential carcinogenic effect to progesterone secreted during menstrual cycles but not to progesterone during pregnancy. They did not discuss breast cancer evidence from progesterone/progestin therapeutics. They argue that in genetic primary amenorrhea, a hypothetic lower risk of breast cancer could be due to the lack of progesterone, despite the progesterone/progestin in hormone replacements these women receive. Fourth, they advocate a regulatory effect of progesterone on several genes potentially involved in cancer genesis. In particular, they attribute a lower risk of breast cancer in women with Mayer-Rokitansky-Küster-Hauser syndrome to a defect in the progesterone-stimulated Wnt4 gene. However, this defect is only present in a small subset. Thus, the postulated progesterone breast cancer risk is unconvincing, which we discuss point by point in this commentary.