A Pooled Analysis of Breastfeeding and Breast Cancer Risk by Hormone Receptor Status in Parous Hispanic Women

Dual role of pregnancy in breast cancer risk

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

[Association between reproductive history, breast cancer subtype, and survival in premenopausal women]

BACKGROUND AND OBJECTIVE

Reproductive history influences breast cancer risk. We analysed its association with tumour subtype and survival in premenopausal women.

PATIENTS AND METHODS

Retrospective, observational study of premenopausal women with stage I-III breast carcinoma in the last 20 years. Review of reproductive history, clinical data, and treatments in health records.

RESULTS

In 661 premenopausal women (32.40% of 1377 total cases), median age was 47 years (19-53), menarche 12 (7-17), first delivery 28 (16-41) and number of deliveries 2 (0-9). One hundred and eleven (18.20%) were nulliparous. Three hundred and fifty-nine (58.80%) used natural lactation, with a median duration of 6 months. Anovulatory drugs were used by 271 (44.40%), with a median duration of 36 months. Associations were found between menarche <10 years and lower risk of luminal subtype (OR: 0.52, 95% CI: 0.28-0.94; P=.03), between menarche >11 years and lower risk of HER2 subtype (OR: 0.50, 95% CI: 0.26-0.97; P=.04) and between first birth >30 years and lower risk of triple negative subtype (OR: 0.40, 95% CI: 0.17-0.93; P=.03). The 20-year overall and disease-free survival probabilities were 0.80 (95% CI: 0.71-0.90) and 0.72 (95% CI: 0.64-0.79) respectively. Patients with ≥1 delivery had better overall survival than nulliparous patients (HR: 0.51, 95% CI: 0.27-0.96, P=.04).

CONCLUSIONS

The findings suggest an association between age at menarche and age at first delivery and breast cancer subtype. Nulliparity is associated with worse survival.

Dietary pattern and other factors of breast cancer among women: a case control study in Northwest Ethiopia

INTRODUCTION

Breast cancer is presently the most commonly diagnosed cancer in women, and it stands as the leading cause of cancer-related deaths worldwide. Notably, breast cancer rates have seen a significant increase in sub-Saharan African countries, including Ethiopia. Several risk factors contribute to breast cancer, some of which can be modified, while others are inherent. Promoting a healthier diet is strongly encouraged as a preventive measure against breast cancer. However, it's noteworthy that no previous research has investigated the connection between dietary patterns and the risk of breast cancer among Ethiopian women. Therefore, the primary objective of the current study is to examine the relationship between dietary patterns, socioeconomic and behavior factors associated with breast cancer in Ethiopian women.

METHODS

A case-control study was conducted at an institution in Bahir Dar, Northwest Ethiopia, involving 260 women, comprising 86 cases and 174 controls. We administered a standardized and validated questionnaire to assess a range of sociodemographic, reproductive, clinical, lifestyle, and dietary characteristics through face-to-face interviews. To analyze the differences between the cases and controls, we employed the Chi-square test. Furthermore, we assessed the relationships between these variables using binary multivariate logistic regression. To measure the association between variables, we utilized odds ratios with 95% confidence intervals.

RESULTS

The results of the multivariate analysis indicated that participants in the younger age group had significantly lower odds of developing breast cancer (AOR = 0.05; 95% CI: 0.00-0.91) compared to those in the older age group. Additionally, women who breastfed their children for shorter durations were 3.66 times more likely to develop breast cancer (AOR = 3.66; 95% CI: 2.78-6.89) than those who breastfed for longer periods. Furthermore, women with sedentary lifestyles faced a significantly higher risk of breast cancer, with odds 10.53 times greater (AOR = 10.53; 95% CI: 5.21-21.36) than their counterparts who engaged in moderate or highly active lifestyles. Lastly, participants who had previously undergone chest therapy were 6.43 times more likely to develop breast cancer (AOR = 6.43; 95% CI: 3.20-13.90) compared to those who had not.

CONCLUSIONS

Breast cancer prevention interventions, including breastfeeding counseling and increased physical activity should be recognized as a central strategy for lowering breast cancer risk. Furthermore, healthcare providers should aim to minimize exposure to chest radiation therapy.

A Narrative Review of Breastfeeding and Its Correlation With Breast Cancer: Current Understanding and Outcomes

Breastfeeding has been extensively studied in relation to breast cancer risk. The results of the reviewed studies consistently show a decreased risk of breast cancer associated with breastfeeding, especially for 12 months or longer. This protective effect is attributed to hormonal, immunological, and physiological changes during lactation. Breastfeeding also appears to have a greater impact on reducing breast cancer risk in premenopausal women and specific breast cancer subtypes. Encouraging breastfeeding has dual benefits: benefiting infants and reducing breast cancer risk long-term. Healthcare professionals should provide evidence-based guidance on breastfeeding initiation, duration, and exclusivity, while public health policies should support breastfeeding by creating enabling environments. This review examines the existing literature and analyzes the correlation between breastfeeding and breast cancer risk.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Perception and practice of breastfeeding in public in Poland

BACKGROUND

The aim of the study was to get to know polish women's opinions and experiences regarding breastfeeding in public.

MATERIAL AND METHODS

A one-time 11-question survey aimed at women during lactation or breastfeeding in the past who completed a paper questionnaire or online questionnaire on the website (www.laktacja.pl). The study was conducted electronically from 1 September 2019 to 31 March 2020 in Maternity and Neonatal Departments, primary health-care clinics in various Polish cities. Data from 700 questionnaires were statistically analysed with the use of Pearson's chi-squared test of independency or Fisher's exacts test when applicable (small cell counts).

RESULTS

90% of the surveyed women expressed the opinion that it should be possible to breastfeed in public, and 78% of women have had such an experience. Most often it was their own cars, a room for a mother and child, a hall or just a place available when there was a need to feed the child (e.g., a bench, cafe, toilet). About 10% of women faced criticism while breastfeeding in a public place, and 8.6% of women have never breastfed the child out of the house due to the lack of proper place and conditions, embarrassment and no sympathy from other people.

CONCLUSION

Taking into account the benefits of long-term breastfeeding and the comfort of breastfeeding women, their children and the environment, it is necessary to create dedicated places for breastfeeding in public places.

Racial/ethnic differences in postmenopausal breast cancer risk by hormone receptor status: The multiethnic cohort study

There are racial/ethnic differences in the incidence of hormone receptor positive and negative breast cancer. To understand why these differences exist, we investigated associations between hormone-related factors and breast cancer risk by race/ethnicity in the Multiethnic Cohort (MEC) Study. Among 81 511 MEC participants (Native Hawaiian, Japanese American, Latina, African American and White women), 3806 estrogen receptor positive (ER+) and 828 ER- incident invasive breast cancers were diagnosed during a median of 21 years of follow-up. We used Cox proportional hazards regression models to calculate associations between race/ethnicity and breast cancer risk, and associations between hormone-related factors and breast cancer risk by race/ethnicity. Relative to White women, ER+ breast cancer risk was higher in Native Hawaiians and lower in Latinas and African Americans; ER- disease risk was higher in African Americans. We observed interaction with race/ethnicity in associations between oral contraceptive use (OC; Pint .03) and body mass index (BMI; Pint .05) with ER+ disease risk; ever versus never OC use increased risk only in Latinas and positive associations for obese versus lean BMI were strongest in Japanese Americans. For ER- disease risk, associations for OC use, particularly duration of use, were strongest for African Americans (Pint .04). Our study shows that associations of OC use and obesity with ER+ and ER- breast cancer risk differ by race/ethnicity, but established risk factors do not fully explain racial/ethnic differences in risk. Further studies are needed to identify factors to explain observed racial/ethnic differences in breast cancer incidence.