Prolactin levels, breast-feeding and milk production in a cohort of young healthy women from high-risk breast cancer families: implications for breast cancer risk

A Scoping Review of Primary Breast Cancer Risk Reduction Strategies in East and Southeast Asia

Breast cancer (BC) screening enables early detection and timely treatment of cancer. Improving the effectiveness of BC screening can be accomplished by personalizing screening schedules according to each woman's specific risk level. However, when informing women about their risk classification, especially those at high risk, it is important to give clear recommendations on how to lower their risk. BC risk reduction comprises lifestyle modifications, preventive surgery, and chemoprevention, with the latter two being particularly applicable to high-risk individuals. Public health guidance on risk-reducing interventions is heterogeneous and context-dependent. We conducted a scoping review on BC surgical interventions and chemoprevention in East and Southeast Asia in publications between 2010 and 2024. We searched two databases and identified 23 publications relevant for inclusion. The highest number of publications came from South Korea (n = 9). More publications discussed surgical interventions compared to pharmacological interventions. The studies were largely observational and utilized data from medical records. Most studies defined high-risk individuals as BRCA carriers, many of whom previously had cancer. The field would benefit from randomized studies of BC prevention strategies focusing on Asian populations. Future research could explore women's sentiments towards chemoprevention compared to prophylactic surgery and could extend the definition of high-risk individuals beyond BRCA carriers.

Reproductive Factors, Use of Exogenous Hormones, and Pancreatic Cancer Incidence: The Norwegian Women and Cancer Study

Introduction

The incidence of pancreatic cancer is increasing worldwide and characterized by a particularly low survival rate. Studies have reported weak and inconsistent evidence for associations among reproductive factors, use of exogenous hormones, and pancreatic cancer incidence in women.

Purpose

To investigate relationships between reproductive factors, exogenous hormones, and the rate of pancreatic cancer incidence in a large population-based prospective cohort of women in Norway.

Methods

We used data from the Norwegian Women and Cancer study on 588 incident cases of pancreatic cancer diagnosed among 165,419 women, with mean follow-up of 18.7 years. Cox proportional-hazard models were used to estimate HRs and 95% CIs for associations of interest.

Results

Cumulative breastfeeding duration >24 months was associated with 63% decreased incidence of pancreatic cancer compared to no breastfeeding. We observed an inverse linear dose–response trend between cumulative breastfeeding duration and pancreatic cancer incidence, which was confirmed in parous women and ever-smokers. Higher age at first birth and menopause were inversely associated with pancreatic cancer incidence, though with less precise effect estimates. Current use of oral contraceptives was associated with a doubling of pancreatic cancer incidence, but the analysis was hampered by a small number of cases. There was no evidence of any associations between age at menarche, parity or use of menopausal hormone therapy, and incidence of pancreatic cancer.

Conclusion

Our results suggest a potential protective effect of breastfeeding duration against pancreatic cancer incidence. Inconsistent results for the other reproductive factors suggested no important role of estrogens in pancreatic cancer etiology.

Current smoking is associated with a larger waist circumference and a more androgenic profile in young healthy women from high-risk breast cancer families

The purpose was to elucidate the interplay between current smoking, anthropometric measurements, and endogenous hormone levels in women ≤ 40 years. Questionnaires on lifestyle and reproductive factors were completed by 269 healthy women from high-risk breast cancer families between 1996 and 2006 in Sweden. Blood samples for analyses of plasma testosterone, estradiol, androstenedione, sex hormone-binding globulin, and body measurements were obtained 5–10 days before predicted onset of the next menstrual period. Women without smoking status, who were currently breastfeeding, or using hormonal contraception other than combined oral contraceptives (OCs) were excluded (n = 27). Current smokers (n = 57) had larger waist circumference (_adjp = 0.004) and waist-to-hip ratio (WHR) (_adjp = 0.007) than non-smokers (n = 185). In non-OC users, adjusted mean androstenedione levels were higher in current smokers compared with non-smokers (10.3 vs. 8.6 nmol/L; _adjp = 0.0002). While in current OC users estradiol levels were higher in smokers compared with non-smokers (22.5 vs. 17.4 pg/mL; _adjp = 0.012). In multivariable models, WHR was associated with both current smoking (_adjp ≤ 0.016) and higher levels of androstenedione (_adjp = 0.05) or bioavailable testosterone (_adjp = 0.001). Among non-OC users, a more androgenic profile was observed in current smokers compared with non-smokers, but not in current OC users. Irrespective of OC use, current smoking was associated with increased waist circumference.

Breastfeeding and Risk of Breast Cancer: Case-Control Study

The aim of this study was to investigate a possible association of breast cancer occurrence in women with their breastfeeding experience. A matched case-control study was conducted in Kragujevac, Serbia. A total of 382 women (191 cases with breast cancer and 191 controls) were interviewed, but the data were explored on breastfeeding and breast cancer only among parous women (339 women). Logistic regression was used to calculate odds ratios (ORs) as estimates of the relative risk of breast cancer. Compared with controls, significantly more cases ever breastfed [adjusted OR (ORadj) = 2.90, 95 percent confidence interval (95 percent CI) 1.02-8.22], breastfed all their children (ORadj = 2.93; 95 percent CI 1.03-8.29), and had longer lifetime duration of breastfeeding (ORadj = 3.44, 95 percent CI 1.15-10.24 for 13 or more months). In comparison with controls, significantly more cases breastfed at first birth (ORadj = 3.17, 95 percent CI 1.36-7.37). Breast cancer risk increased if first breastfeeding occurred at an older age (p for trend = .042) and with longer duration of breastfeeding (p for trend = .037). Our study is one of the few in which breastfeeding was found to be a risk factor for breast cancer.

Prolactin determinants in healthy women: A large cross-sectional study within the EPIC cohort

BACKGROUND

Experimental and epidemiologic data suggest that higher circulating prolactin is associated with breast cancer risk; however, how various risk factors for breast cancer influence prolactin levels in healthy women is not clear.

METHODS

We analyzed cross-sectional associations between several suggested reproductive and lifestyle risk factors for breast cancer and circulating prolactin among pre- and postmenopausal women, taking into account the use of current postmenopausal hormone therapy, among 2,560 controls from a breast cancer nested case-control study within the EPIC cohort.

RESULTS

Adjusted geometric mean prolactin levels were significantly higher among premenopausal women, and among postmenopausal women using hormone therapy compared with nonusers (8.2, 7.0, and 6.3 ng/mL, respectively; Pcat = <0.0001). Furthermore, prolactin levels were significantly higher among users of combined estrogen-progestin hormone therapy compared with users of estrogen-alone hormone therapy (6.66 vs. 5.90 ng/mL; Pcat = 0.001). Prolactin levels were lower among parous women compared with nulliparous women (8.61 vs. 10.95 ng/mL; Pcat = 0.0002, premenopausal women); the magnitude of this difference depended on the number of full-term pregnancies (22.1% lower, ≥3 vs. 1 pregnancy, Ptrend = 0.01). Results for parity were similar but lower in magnitude among postmenopausal women. Prolactin did not vary by other studied factors, with the exception of lower levels among postmenopausal smokers compared with never smokers.

CONCLUSIONS

Our study shows that current hormone therapy use, especially the use of combined hormone therapy, is associated with higher circulating prolactin levels in postmenopausal women, and confirms prior findings of lower circulating prolactin in parous women.

IMPACT

Our study extends the knowledge linking various breast cancer risk factors with circulating prolactin.

Breastfeeding in relation to risk of different breast cancer characteristics

BACKGROUND

The aim of this present study was to examine duration of breastfeeding in relation to the risk of different subgroups of breast cancer. A prospective cohort, The Malmö Diet and Cancer study, including 14092 parous women, were followed during a mean of 10.2 years and a total of 424 incident breast cancers were diagnosed.

METHODS

Tumours were classified regarding invasiveness, tumour size, axillary lymph node status, Nottingham grade, tumour proliferation (Ki67), HER2, cyclin D1 and p27, WHO histological type and hormone receptor status. Duration of breastfeeding was measured using total time of breastfeeding, categorized in quartiles using the lowest as the reference group (<4.0, ≥4.0- < 8.0, ≥8.0- < 13.0 and ≥13.0 months). Average duration of breastfeeding per child and breastfeeding duration of the first child were also used as exposures in separate analyses. Relative risks, with 95% confidence intervals, were obtained using a Cox's proportional hazards analysis adjusted for potential confounders.

RESULTS

Overall risk for breast cancer was similar in all quartiles of breastfeeding. No strong results regarding breastfeeding duration and breast cancer subgroups were seen. A few results indicated an association between a relatively long duration of breastfeeding and tumours with high proliferation (Ki67) and grade III histological grade.

CONCLUSIONS

Breastfeeding duration was not associated with breast cancer risk and no strong results were seen with regard to breast cancer subgroups.

Excessive milk production during breast-feeding prior to breast cancer diagnosis is associated with increased risk for early events

Breast-feeding is a known protective factor against breast cancer. Breast-feeding duration is influenced by hormone levels, milk production, and lifestyle factors. The aims were to investigate how breast-feeding duration and milk production affected tumor characteristics and risk for early breast cancer events in primary breast cancer patients. Between 2002 and 2008, 634 breast cancer patients in Lund, Sweden, took part in an ongoing prospective cohort study. Data were extracted from questionnaires, pathology reports, and patients’ charts from 592 patients without preoperative treatment. Breast-feeding duration ≤12 months of the first child was associated with higher frequency of ER+/PgR+ tumors (P=0.02). Median follow-up time was 4.9 years. Higher risk for early events was observed for breast-feeding duration of first child >12 months (LogRank P=0.001), total breast-feeding duration >12 months (LogRank P=0.008), as well as ‘excessive milk production’ during breast-feeding of the first child (LogRank P=0.001). Patients with ‘almost no milk production’ had no events. In a multivariable model including both ‘excessive milk production’ and breast-feeding duration of the first child >12 months, both were associated with a two-fold risk for early events, adjusted HRs 2.33 (95% CI: 1.25-4.36) and 2.39 (0.97-5.85), respectively, while total breast-feeding duration was not. ‘Excessive milk production’ was associated with a two-fold risk of early distant metastases, adjusted HR 2.59 (1.13-5.94), but not duration. In conclusion, ‘excessive milk production’ during breast-feeding was associated with higher risk for early events independent of tumor characteristics, stressing the need to consider host factors in the evaluation of prognostic markers.

Prolactin and autoimmunity

Sex hormones, especially estrogen and prolactin (PRL), have an important role in modulating the immune response. PRL is secreted from the pituitary gland as well as other organs and cells particularly lymphocytes. PRL has an immune stimulatory effect and promotes autoimmunity. PRL interferes specifically with B cell tolerance induction, enhances proliferative response to antigens and mitogens and increases the production of immune globulins, cytokines and autoantibodies. Hyperprolactinemia (HPRL) in women present with clinical manifestations of galactorrhea, primary or secondary amenorrhea, delayed menarche or a change in the menses either in the amount or in the regularity. Furthermore in the last 2 decades multi-organ and organ specific autoimmune diseases like systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjogren's syndrome (SS), Hashimoto's thyroiditis (HT), multiple sclerosis (MS), psoriasis, hepatitis C patients, Behçet's disease, peripartum cardiomyopathy (PPCM) and active celiac disease were discussed to be associated with HPRL. There is data showing correlation between PRL level and diseases activity in few diseases. Genetic factors may have a role in humans as in animal models. The PRL isoforms based on the differences in the amino acid sequence and size of the cytoplasmic domain have an important effect on the bioactivity on prolactin receptors (PRL-Rs).

Associations of body size and reproductive factors with circulating levels of sex hormones and prolactin in premenopausal Japanese women

OBJECTIVE

Body size and reproductive factors are important risk factors of breast cancer. The aim of the present study was to examine the associations of these factors with blood concentrations of sex hormones and prolactin in premenopausal Japanese women.

METHODS

We measured the plasma concentrations of estradiol, estrone, testosterone, dehydroepiandrosterone sulfate (DHEAS), sex hormone-binding globulin (SHBG), follicle-stimulating hormone, luteinizing hormone, and prolactin among 436 women who had regular menstrual cycles less than 40 days long. Information on menstrual and reproductive factors including history of breastfeeding was obtained using a self-administered questionnaire. Height and weight were measured.

RESULTS

After controlling for age and the phase of the menstrual cycle, the body mass index (BMI) was significantly inversely associated with total estradiol, estrone and SHBG and significantly positively associated with total and free testosterone and DHEAS. Nulliparous women had significantly higher levels of total and free testosterone, DHEAS, and prolactin than parous women. Duration of breastfeeding for the first child was significantly inversely associated with free testosterone and prolactin levels.

CONCLUSIONS

The data suggest that an increased risk of premenopausal breast cancer associated with low BMI is partially mediated by an increased total estradiol. Androgens and prolactin may explain the breast cancer protection provided by giving birth and breastfeeding.

Coffee intake and CYP1A2*1F genotype predict breast volume in young women: implications for breast cancer

As breast volume may be associated with heart cancer risk, we studied the relationship between breast volume, CYP1A2*1F and coffee intake. Among healthy premenopausal non-hormone users, 3+ cups per day was associated with lower volume only in C-allele carriers (P_interaction=0.02), which is consistent with reports that coffee protects only C-allele carriers against breast cancer.