Increased Incidence of Breast Cancer in Postmenopausal Women with High Body Mass Index at the Modena Screening Program

Excess body weight and postmenopausal breast cancer: Emerging molecular mechanisms and perspectives

Postmenopausal, obese women have a significantly higher risk of developing estrogen receptor-positive (ER+) breast tumors, that are resistant to therapies and are associated with higher recurrence and death rates. The global prevalence of overweight/obese women has reached alarming proportions and with postmenopausal ER+ breast carcinoma (BC) having the highest incidence among the three obesity-related cancers in females (i.e., breast, endometrial and ovarian), this is of significant concern. Elucidation of the precise molecular mechanisms underlying the pro-cancerous action of obesity in ER+BC is therefore critical for disease prevention and novel treatment initiatives. Interestingly, accumulating data has shown opposing relationships between obesity and cancer in either pre- or post-menopausal women. Excess body weight is associated with an increased risk of breast cancer in postmenopausal women and a decreased risk in pre-menopausal women. Moreover, excess adiposity during early life appears to be protective against postmenopausal breast cancer, including both ER+ and ER negative BC subtypes. Overall, estrogen-dependent mechanisms have been implicated as the main driving force in obesity-related breast tumorigenesis. In the present review we discuss the epidemiologic and mechanistic aspects of association between obesity and breast tumors after menopause, mainly in the context of hormone dependency. Molecular and cellular events underlying this association present as potential avenues for both therapeutic intervention as well as the prevention of BC-promoting processes linked to excess adiposity, which is proving to be vital in an increasingly obese global population.

Visualization and Quantification of the Association Between Breast Cancer and Cholesterol in the All of Us Research Program

Epidemiologic evidence for the association of cholesterol and breast cancer is inconsistent. Several factors may contribute to this inconsistency, including limited sample sizes, confounding effects of antihyperlipidemic treatment, age, and body mass index, and the assumption that the association follows a simple linear function. Here, we aimed to address these factors by combining visualization and quantification a large-scale contemporary electronic health record database (the All of Us Research Program). We find clear visual and quantitative evidence that breast cancer is strongly, positively, and near-linearly associated with total cholesterol and low-density lipoprotein cholesterol, but not associated with triglycerides. The association of breast cancer with high-density lipoprotein cholesterol was non-linear and age dependent. Standardized odds ratios were 2.12 (95% confidence interval 1.9-2.48), P = 5.6 × 10^-31 for total cholesterol; 1.99 (1.75-2.26), P = 2.6 × 10^-26 for low-density lipoprotein cholesterol; 1.69 (1.3-2.2), P = 9.0 × 10^-5 for high-density lipoprotein cholesterol at age < 56; and 0.65 (0.55-0.78), P = 1.2 × 10^-6 for high-density lipoprotein cholesterol at age ⩾ 56. The inclusion of the lipid levels measured after antihyperlipidemic treatment in the analysis results in erroneous associations. We demonstrate that the use of the logistic regression without inspecting risk variable linearity and accounting for confounding effects may lead to inconsistent results.

Obesity and breast cancer

The paper presents an analysis of the latest literature data on the problem of obesity and breast cancer (BC). This review presents modern approaches to the diagnosis of BC in obese patients, new molecular methods of breast imaging,  analyzes the features of the course of BC with obesity depending on menstrual status, molecular biological subtypes of the tumor, the mechanisms of the development of BC against the background of obesity.

Preventive Health Screening in Veterans Undergoing Bariatric Surgery

INTRODUCTION

Individuals with obesity are vulnerable to low rates of preventive health screening. Veterans with obesity seeking bariatric surgery are also hypothesized to have gaps in preventive health screening. Evaluation in a multidisciplinary bariatric surgery clinic is a point of interaction with the healthcare system that could facilitate improvements in screening.

METHODS

This is a retrospective cohort study of 381 consecutive patients undergoing bariatric surgery at a Veterans Affairs Hospital from January 2010 to October 2021. Age- and sex-appropriate health screening rates were determined at initial referral to a multidisciplinary bariatric surgery clinic and at the time of surgery. Rates of guideline concordance at both time points were compared using McNemar's test. Univariate and multivariate analyses were performed to identify the risk factors for nonconcordance.

RESULTS

Concordance with all recommended screening was low at initial referral and significantly improved by time of surgery (39.1%‒63.8%; p<0.001). Screening rates significantly improved for HIV (p<0.001), cervical cancer (p=0.03), and colon cancer (p<0.001). Increases in BMI (p=0.005) and the number of indicated screening tests (p=0.029) were associated with reduced odds of concordance at initial referral. Smoking history (p=0.012) and increasing distance to the nearest Veterans Affairs Medical Center (p=0.039) were associated with reduced odds of change from nonconcordance at initial referral to concordance at the time of surgery.

CONCLUSIONS

Rates of preventive health screening in Veterans with obesity are low. A multidisciplinary bariatric surgery clinic is an opportunity to improve preventive health screening in Veterans referred for bariatric surgery.

Rat Mammary carcinoma susceptibility 3 (Mcs3) pleiotropy, socioenvironmental interaction, and comparative genomics with orthologous human 15q25.1-25.2

Genome-wide association studies of breast cancer susceptibility have revealed risk-associated genetic variants and nominated candidate genes; however, the identification of causal variants and genes is often undetermined by genome-wide association studies. Comparative genomics, utilizing Rattus norvegicus strains differing in susceptibility to mammary tumor development, is a complimentary approach to identify breast cancer susceptibility genes. Mammary carcinoma susceptibility 3 (Mcs3) is a Copenhagen (COP/NHsd) allele that confers resistance to mammary carcinomas when introgressed into a mammary carcinoma susceptible Wistar Furth (WF/NHsd) genome. Here, Mcs3 was positionally mapped to a 7.2-Mb region of RNO1 spanning rs8149408 to rs107402736 (chr1:143700228-150929594, build 6.0/rn6) using WF.COP congenic strains and 7,12-dimethylbenz(a)anthracene-induced mammary carcinogenesis. Male and female WF.COP-Mcs3 rats had significantly lower body mass compared to the Wistar Furth strain. The effect on female body mass was observed only when females were raised in the absence of males indicating a socioenvironmental interaction. Furthermore, female WF.COP-Mcs3 rats, raised in the absence of males, did not develop enhanced lobuloalveolar morphologies compared to those observed in the Wistar Furth strain. Human 15q25.1-25.2 was determined to be orthologous to rat Mcs3 (chr15:80005820-82285404 and chr15:83134545-84130720, build GRCh38/hg38). A public database search of 15q25.1-25.2 revealed genome-wide significant and nominally significant associations for body mass traits and breast cancer risk. These results support the existence of a breast cancer risk-associated allele at human 15q25.1-25.2 and warrant ultrafine mapping of rat Mcs3 and human 15q25.1-25.2 to discover novel causal genes and variants.

Breast cancer microenvironment and obesity: challenges for therapy

Women with obesity who develop breast cancer have a worsened prognosis with diminished survival rates and increased rates of metastasis. Obesity is also associated with decreased breast cancer response to endocrine and chemotherapeutic treatments. Studies utilizing multiple in vivo models of obesity as well as human breast tumors have enhanced our understanding of how obesity alters the breast tumor microenvironment. Changes in the complement and function of adipocytes, adipose-derived stromal cells, immune cells, and endothelial cells and remodeling of the extracellular matrix all contribute to the rapid growth of breast tumors in the context of obesity. Interactions of these cells enhance secretion of cytokines and adipokines as well as local levels of estrogen within the breast tumor microenvironment that promote resistance to multiple therapies. In this review, we will discuss our current understanding of the impact of obesity on the breast tumor microenvironment, how obesity-induced changes in cellular interactions promote resistance to breast cancer treatments, and areas for development of treatment interventions for breast cancer patients with obesity.

Obesity in Postmenopausal Breast Cancer Patients: It Is Time to Improve Actions for a Healthier Lifestyle. The Results of a Comparison Between Two Italian Regions With Different "Presumed" Lifestyles

Background

Adult body fatness is a convincing risk factor for postmenopausal breast cancer. With the aim to compare the different breast cancer (BC) features in Northern and Southern Italy, we investigated the relationship between BMI and BC characteristic in two groups of patients referred in the Modena and Lecce breast units.

Materials and Methods

A retrospective analysis of a continuous series of BC patients referred to the Città di Lecce Hospital and the Modena Cancer Center, from January 2019 to December 2020 was performed. We identified four groups of BMI at BC diagnosis: underweight, BMI <18.5 kg/m²; normal weight, BMI ≥ 18.5–24.9 kg/m²; overweight, BMI ≥ 25.0–29.9 kg/m²; obese, BMI ≥30.0 kg/m². BC characteristics and clinical outcomes were analyzed by the Kolmogorov-Smirnov test and Mann-Whitney U test; categorical data were compared using Pearson’s chi-square test, and dicotomic data were compared by odds ratio.

Results

Nine hundred seventy-seven BC patients were included in the analysis. Overall, 470 were from Modena and 507 from Lecce. No differences were observed in the mean age of BC patients of Modena (61,42) and Lecce (62,08). No statistical differences between the two populations were shown in terms of tumor characteristics and pathological stage. Conversely, a statistical difference of BMI between the BC patients coming from Modena and Lecce (25.87 and 27.81, respectively; p = 0.000001) was found. BC patients diagnosed in Lecce at age ≥70 years had higher median BMI compared with the ones from Modena (p = 0.000002). The increased BMI in this aged population was also associated to larger tumor size (p = 0.040).

Conclusion

The rate of overweight and obesity was higher in BC women living in Southern Italy, despite the presumed nutrition according to the so-called Mediterranean type dietary pattern. Unexpectedly, an increased BMI rate and a relationship with larger tumor size were found in Southern BC patients aged ≥70 years. Our findings strongly support the need for promoting a healthier lifestyle model in Italy, with the aim of reducing the rate of the obesity and, consequently, the increased risk of BC.

Relationship between body mass index and cholesterol levels with histopathological grading of breast cancer

BACKGROUND

Breast cancer, a global health problem with a high mortality rate, has several risk factors, including obesity and increased lipid profile. Postmenopausal obesity is associated with estrogen production from adipose tissue, while abnormal cell growth is triggered by insulin-like growth factor 1 (IGF-1) and insulin. Obesity could be assessed by measuring body mass index (BMI). An increase in lipid profile signifies an increased risk for breast cancer. Histopathological findings in the form of grading and differentiation can indicate how serious the condition is. Breast cancer with good differentiation is always associated with a positive prognosis.

OBJECTIVE

This observational analytic study aims to determine the relationship between BMI and cholesterol levels based on the menopausal status and the histopathological grading findings of breast cancer patients.

METHODS

The observational cross-sectional study analyzed histopathological grading, total cholesterol level, and body mass index. Data were analyzed with Spearman rank correlation statistical test, and the results are significant when the p-value is <0.05.

RESULTS

Analyzing the relationship between cholesterol levels and histopathological gradings indicated a moderate correlation. The results of another correlation test based on menopausal status showed a weak correlation value, while menopause was said to be significant, indicating a moderate correlation. However, results from the analysis of BMI data in the menopausal subject group were associated with histopathological assessment.

CONCLUSIONS

There is a relationship between cholesterol levels and histopathological degrees in the two menopausal status groups. However, no relationship was found between BMI and the histopathological grades of breast cancer.

Breast adipocyte size associates with ipsilateral invasive breast cancer risk after ductal carcinoma in situ

Although ductal carcinoma in situ (DCIS) is a non-obligate precursor to ipsilateral invasive breast cancer (iIBC), most DCIS lesions remain indolent. Hence, overdiagnosis and overtreatment of DCIS is a major concern. There is an urgent need for prognostic markers that can distinguish harmless from potentially hazardous DCIS. We hypothesised that features of the breast adipose tissue may be associated with risk of subsequent iIBC. We performed a case-control study nested in a population-based DCIS cohort, consisting of 2658 women diagnosed with primary DCIS between 1989 and 2005, uniformly treated with breast conserving surgery (BCS) alone. We assessed breast adipose features with digital pathology (HALO®, Indica Labs) and related these to iIBC risk in 108 women that developed subsequent iIBC (cases) and 168 women who did not (controls) by conditional logistic regression, accounting for clinicopathological and immunohistochemistry variables. Large breast adipocyte size was significantly associated with iIBC risk (odds ratio (OR) 2.75, 95% confidence interval (95% CI) = 1.25-6.05). High cyclooxygenase (COX)-2 protein expression in the DCIS cells was also associated with subsequent iIBC (OR 3.70 (95% CI = 1.59-8.64). DCIS with both high COX-2 expression and large breast adipocytes was associated with a 12-fold higher risk (OR 12.0, 95% CI = 3.10-46.3, P < 0.001) for subsequent iIBC compared with women with smaller adipocyte size and low COX-2 expression. Large breast adipocytes combined with high COX-2 expression in DCIS is associated with a high risk of subsequent iIBC. Besides COX-2, adipocyte size has the potential to improve clinical management in patients diagnosed with primary DCIS.

Effects of GSTT1 and GSTM1 polymorphisms in glutathione levels and breast cancer development in Brazilian patients

Polymorphisms in the glutathione transferase enzymes (GSTs) genes have been associated with susceptibility to develop breast cancer (BC), but few are known regarding its role on this disease prognosis and impact on antioxidant status. This study evaluated the polymorphisms of GSTM1 and GSTT1 genes and their relationship with BC susceptibility and prognostic, as well as its impact on plasma reduced glutathione (GSH) levels. The present study included 121 women with invasive ductal BC and 151 healthy controls. Polymorphisms analyses were performed using the polymerase chain reaction (PCR) technique and GSH levels were measured with the Ellman's reagent. GSTT1 (OR 1.29; p = 0.39) and GSTM1 (OR 1.03; p = 0.91) polymorphisms did not show any association with BC susceptibility. The mean concentration values in nmol/L of GSH were 20.37 ± 5.82 for patients with null genotypes for both genes, 19.75 ± 3.47 for null GSTT1, 17.22 ± 1.35 for active GSTT1, 18.82 ± 1.96 for absent GSTM1, and 16.59 ± 1.66 for active GSTM1, but no significance was found. Therefore, it can be concluded that the behavior of these polymorphisms concerning BC might be not only related to the absence of enzymatic expression but may also be related to the body's response with its antioxidant mechanisms and it should be further studied.

Lifestyle Intervention on Body Weight and Physical Activity in Patients with Breast Cancer can reduce the Risk of Death in Obese Women: The EMILI Study

Background obesity and sedentary lifestyle have been shown to negatively affect survival in breast cancer (BC). The purpose of this study was to test the efficacy of a lifestyle intervention on body mass index (BMI) and physical activity (PA) levels among BC survivors in Modena, Italy, in order to show an outcome improvement in obese and overweight patients. Methods: This study is a single-arm experimental design, conducted between November 2009 and May 2016 on 430 women affected by BC. Weight, BMI, and PA were assessed at baseline, at 12 months, and at the end of the study. Survival curves were estimated among normal, overweight, and obese patients. Results: Mean BMI decreased from baseline to the end of the study was equal to 2.9% (p = 0.065) in overweight patients and 3.3% in obese patients (p = 0.048). Mean PA increase from baseline to the end of the study was equal to 125% (p < 0.001) in normal patients, 200% (p < 0.001) in overweight patients and 100% (p < 0.001) in obese patients. After 70 months of follow-up, the 5-year overall survival (OS) rate was 96%, 96%, and 93%, respectively in normal, obese, and overweight patients. Overweight patients had significantly worse OS than normal ones (HR = 3.69, 95%CI = 1.82–4.53 p = 0.027) whereas no statistically significant differences were seen between obese and normal patients (HR 2.45, 95%CI = 0.68–8.78, p = 0.169). Conclusions: A lifestyle intervention can lead to clinically meaningful weight loss and increase PA in patients with BC. These results could contribute to improving the OS in obese patients compared to overweight ones.

Weighing the Risk: effects of Obesity on the Mammary Gland and Breast Cancer Risk

Obesity is a preventable risk factor for breast cancer following menopause. Regardless of menopausal status, obese women who develop breast cancer have a worsened prognosis. Breast tissue is comprised of mammary epithelial cells organized into ducts and lobules and surrounded by adipose-rich connective tissue. Studies utilizing multiple in vivo models of obesity as well as human breast tissue have contributed to our understanding of how obesity alters mammary tissue. Localized changes in mammary epithelial cell populations, elevated secretion of adipokines and angiogenic mediators, inflammation within mammary adipose tissue, and remodeling of the extracellular matrix may result in an environment conducive to breast cancer growth. Despite these significant alterations caused by obesity within breast tissue, studies have suggested that some, but not all, obesity-induced changes may be mitigated with weight loss. Here, we review our current understanding regarding the impact of obesity on the breast microenvironment, how obesity-induced changes may contribute to breast tumor progression, and the impact of weight loss on the breast microenvironment.

Red clover and lifestyle changes to contrast menopausal symptoms in premenopausal patients with hormone-sensitive breast cancer receiving tamoxifen

PURPOSE

To determine whether a red clover preparation plus dietary intervention administered to premenopausal women with breast cancer (BC), improves menopausal symptoms due to anti-oestrogen treatment, and hence promotes compliance with tamoxifen, prevents weight gain and is safe.

METHODS

Surgically-treated premenopausal women with oestrogen receptor (ER) positive disease taking tamoxifen were recruited to a prospective double-blind randomized trial (NCT03844685). The red clover group (N = 42) received one oral tablet/day (Promensil^® Forte) containing 80 mg red clover extract for 24 months. The placebo group (N = 39) received one oral tablet/day without active ingredient. All women were encouraged to follow a Mediterranean-type diet and keep active. Outcomes were Menopausal Rating Score (MRS), body mass index (BMI), waist and hip girth, insulin resistance, and levels of cholesterol, triglycerides, and sex hormones. As safety indicators, endometrial thickness, breast density, and effects of patient serum on ER-positive BC cell lines were investigated.

RESULTS

MRS reduced significantly (p < 0.0001) with no between-group difference (p = 0.69). The red clover group had significantly greater reductions in BMI and waist circumference (p < 0.0001 both cases). HDL cholesterol increased significantly in both groups (p = 0.01). Hormone levels and insulin resistance changed little. Endometrial thickness remained constant (p = 0.93). Breast density decreased significantly in both groups (p < 0.0001). Proliferation and oestrogen-regulated gene expression didn't differ in cell lines treated with serum from each group.

CONCLUSIONS

This is the first trial to assess red clover in BC patients on tamoxifen. The preparation proved safe clinically and in vitro, and was associated with reduced BMI and waist circumference, but the diet-lifestyle intervention probably improved the menopausal symptoms.

World Cancer Research Fund International: Continuous Update Project-systematic literature review and meta-analysis of observational cohort studies on physical activity, sedentary behavior, adiposity, and weight change and breast cancer risk. Cancer Causes Control. 2019;30:1183-1200. [PMID: 31471762 DOI: 10.1007/s10552-019-01223-w]

PURPOSE

The purpose of the present study was to systematically review the complex associations between energy balance-related factors and breast cancer risk, for which previous evidence has suggested different associations in the life course of women and by hormone receptor (HR) status of the tumor.

METHODS

Relevant publications on adulthood physical activity, sedentary behavior, body mass index (BMI), waist and hip circumferences, waist-to-hip ratio, and weight change and pre- and postmenopausal breast cancer risk were identified in PubMed up to 30 April 2017. Random-effects meta-analyses were conducted to summarize the relative risks across studies.

RESULTS

One hundred and twenty-six observational cohort studies comprising over 22,900 premenopausal and 103,000 postmenopausal breast cancer cases were meta-analyzed. Higher physical activity was inversely associated with both pre- and postmenopausal breast cancers, whereas increased sitting time was positively associated with postmenopausal breast cancer. Although higher early adult BMI (ages 18-30 years) was inversely associated with pre- and postmenopausal breast cancers, adult weight gain and greater body adiposity increased breast cancer risk in postmenopausal women, and the increased risk was evident for HR+ but not HR- breast cancers, and among never but not current users of postmenopausal hormones. The evidence was less consistent in premenopausal women. There were no associations with adult weight gain, inverse associations with adult BMI (study baseline) and hip circumference, and non-significant associations with waist circumference and waist-to-hip ratio that were reverted to positive associations on average in studies accounting for BMI. No significant associations were observed for HR-defined premenopausal breast cancers.

CONCLUSION

Better understanding on the impact of these factors on pre- and postmenopausal breast cancers and their subtypes along the life course is needed.

Obesity and breast cancer screening: Cross-sectional survey results from the behavioral risk factor surveillance system

BACKGROUND

Postmenopausal obese women demonstrate an elevated breast cancer risk and experience increased breast cancer morbidity and mortality compared with women with a normal body mass index (BMI). However, to the authors' knowledge, prior studies have yielded inconclusive results regarding the effects of obesity on mammography screening adherence. Using national cross-sectional survey data, the objective of the current study was to assess the current association between increasing BMI and use of mammography screening.

METHODS

Cross-sectional survey data from the 2016 Behavioral Risk Factor Surveillance System, a state-based national telephone survey of noninstitutionalized adults in the United States, was used to identify the association between mammography screening use and increasing incremental BMI categories, including normal (18.5-24.9 kg/m² ), overweight (25-29.9 kg/m² ), obese class I (30-34.9 kg/m² ), obese class II (35-39.9 kg/m² ), and obese class III (>40 kg/m² ), with adjustments for potential confounders. A multivariable logistic regression model was used to evaluate the effect of each BMI category on self-reported mammography use, using unadjusted and adjusted odds ratios. Effect modification by race/ethnicity was determined by testing interaction terms using Wald tests.

RESULTS

Of 116,343 survey respondents, 33.5% (38,984 respondents) had a normal BMI, 32.6% (37,969 respondents) were overweight, 19.3% (22,416 respondents) were classified as obese class I, 8.4% (9791 respondents) were classified as obese class II, and 6.2% (7183 respondents) were classified as obese class III. There was no statistically significant difference (P < .05) observed with regard to mammography use between women with a normal BMI and obese women from each obese class (classes I-III) when compared individually. There also was no evidence of effect modification by race (P = .53).

CONCLUSIONS

In contrast to prior reports, the results of the current study demonstrated no association between obesity and adherence to screening mammography. These findings may relate to the increasing social acceptance of obesity among women from all racial/ethnic groups and the removal of weight-related facility-level barriers over time.

Leptin produced by obesity-altered adipose stem cells promotes metastasis but not tumorigenesis of triple-negative breast cancer in orthotopic xenograft and patient-derived xenograft models

Background

Breast cancer is the second leading cause of cancer deaths in the USA. Triple-negative breast cancer (TNBC) is a clinically aggressive subtype of breast cancer with high rates of metastasis, tumor recurrence, and resistance to therapeutics. Obesity, defined by a high body mass index (BMI), is an established risk factor for breast cancer. Women with a high BMI have increased incidence and mortality of breast cancer; however, the mechanisms(s) by which obesity promotes tumor progression are not well understood.

Methods

In this study, obesity-altered adipose stem cells (obASCs) were used to evaluate obesity-mediated effects of TNBC. Both in vitro and in vivo analyses of TNBC cell lines were co-cultured with six pooled donors of obASCs (BMI > 30) or ASCs isolated from lean women (lnASCs) (BMI < 25).

Results

We found that obASCs promote a pro-metastatic phenotype by upregulating genes associated with epithelial-to-mesenchymal transition and promoting migration in vitro. We confirmed our findings using a TNBC patient-derived xenograft (PDX) model. PDX tumors grown in the presence of obASCS in SCID/beige mice had increased circulating HLA1⁺ human cells as well as increased numbers of CD44⁺CD24⁻ cancer stem cells in the peripheral blood. Exposure of the TNBC PDX to obASCs also increased the formation of metastases. The knockdown of leptin expression in obASCs suppressed the pro-metastatic effects of obASCs.

Conclusions

Leptin signaling is a potential mechanism through which obASCs promote metastasis of TNBC in both in vitro and in vivo analyses.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1153-9) contains supplementary material, which is available to authorized users.

Obesity, Leptin and Breast Cancer: Epidemiological Evidence and Proposed Mechanisms

The prevalence of obesity has been steadily increasing over the past few decades in several developed and developing countries, with resultant hazardous health implications. Substantial epidemiological evidence has shown that excessive adiposity strongly influences risk, prognosis, and progression of various malignancies, including breast cancer. Indeed, it is now well recognized that obesity is a complex physiologic state associated with multiple molecular changes capable of modulating the behavior of breast tumor cells as well of the surrounding microenvironment. Particularly, insulin resistance, hyperactivation of insulin-like growth factor pathways, and increased levels of estrogen due to aromatization by the adipose tissue, inflammatory cytokines, and adipokines contribute to breast cancerogenesis. Among adipokines, leptin, whose circulating levels increase proportionally to total adipose tissue mass, has been identified as a key member of the molecular network in obesity. This review summarizes the current knowledge on the epidemiological link existing between obesity and breast cancer and outlines the molecular mechanisms underlying this connection. The multifaceted role of the obesity adipokine leptin in this respect is also discussed.

Risks and protective factors for triple negative breast cancer with a focus on micronutrients and infections

Triple negative breast cancer (TNBC) is an aggressive form of breast cancer (BC) with a poor prognosis. Second, patients cannot benefit from targeted therapy, except for those with BRCA1/2 mutations, for whom poly (ADP-ribose) polymerase (PARP) inhibition therapy using olaparib has recently been approved. As global priorities continue to be epidemiological analysis of BC risk factors and early diagnosis, this review focuses on the risks and protective factors associated with TNBC. A PubMed keyword search for new knowledge on the risks and protective factors for TNBC was carried out. We also found statistical information from current online databases concerning the estimated incidence, prevalence and mortality worldwide of this cancer. Traditional risk factors for BC and TNBC are those related to reproduction such as the age of menarche, age of first birth, parity, breastfeeding and age at menopause. Attention needs to be paid to familial BC, weight control, alcohol consumption and regular physical activity. Epidemiological studies on TNBC provide evidence for protective factors such as regular consumption of soya, seafood, green tea, folic acid and vitamin D. Potential risk factors may include night work and viral infectious agents like human papillomavirus (HPV) and Epstein-Barr virus (EBV). Droplet digital methylation-specific PCR (ddMSP) is a possible new screening method for detection of BC including TNBC. Further research is necessary to validate these new factors.

Obesity and adverse breast cancer risk and outcome: Mechanistic insights and strategies for intervention

Answer questions and earn CME/CNE Recent decades have seen an unprecedented rise in obesity, and the health impact thereof is increasingly evident. In 2014, worldwide, more than 1.9 billion adults were overweight (body mass index [BMI], 25-29.9 kg/m2 ), and of these, over 600 million were obese (BMI ≥30 kg/m2 ). Although the association between obesity and the risk of diabetes and coronary artery disease is widely known, the impact of obesity on cancer incidence, morbidity, and mortality is not fully appreciated. Obesity is associated both with a higher risk of developing breast cancer, particularly in postmenopausal women, and with worse disease outcome for women of all ages. The first part of this review summarizes the relationships between obesity and breast cancer development and outcomes in premenopausal and postmenopausal women and in those with hormone receptor-positive and -negative disease. The second part of this review addresses hypothesized molecular mechanistic insights that may underlie the effects of obesity to increase local and circulating proinflammatory cytokines, promote tumor angiogenesis and stimulate the most malignant cancer stem cell population to drive cancer growth, invasion, and metastasis. Finally, a review of observational studies demonstrates that increased physical activity is associated with lower breast cancer risk and better outcomes. The effects of recent lifestyle interventions to decrease sex steroids, insulin/insulin-like growth factor-1 pathway activation, and inflammatory biomarkers associated with worse breast cancer outcomes in obesity also are discussed. Although many observational studies indicate that exercise with weight loss is associated with improved breast cancer outcome, further prospective studies are needed to determine whether weight reduction will lead to improved patient outcomes. It is hoped that several ongoing lifestyle intervention trials, which are reviewed herein, will support the systematic incorporation of weight loss intervention strategies into care for patients with breast cancer. CA Cancer J Clin 2017;67:378-397. © 2017 American Cancer Society.