Body fat distribution and obesity in pre- and postmenopausal breast cancer

The relationship between central obesity and risk of breast cancer: a dose-response meta-analysis of 7,989,315 women

Purpose

Central obesity may contribute to breast cancer (BC); however, there is no dose-response relationship. This meta-analysis examined the effects of central obesity on BC and their potential dose-response relationship.

Methods

In the present study, PubMed, Medline, Embase, and Web of Science were searched on 1 August 2022 for published articles. We included the prospective cohort and case-control studies that reported the relationship between central obesity and BC. Summary effect size estimates were expressed as risk ratios (RRs) or odds ratios (ORs) with 95% confidence intervals (95% CI) and were evaluated using random-effect models. The inconsistency index (I2) was used to quantify the heterogeneity magnitude derived from the random-effects Mantel-Haenszel model.

Results

This meta-analysis included 57 studies (26 case-control and 31 prospective cohort) as of August 2022. Case-control studies indicated that waist circumference (WC) (adjusted OR = 1.18; 95% CI: 1.00-1.38; P = 0.051) and waist-to-hip ratio (WHR) (adjusted OR = 1.28; 95% CI: 1.07-1.53; P = 0.008) were significantly positively related to BC. Subgroup analysis showed that central obesity measured by WC increased the premenopausal (adjusted OR = 1.15; 95% CI: 0.99-1.34; P = 0.063) and postmenopausal (adjusted OR = 1.18; 95% CI: 1.03-1.36; P = 0.018) BC risk and the same relationship appeared in WHR between premenopausal (adjusted OR = 1.38; 95% CI: 1.19-1.59; P < 0.001) and postmenopausal (adjusted OR = 1.41; 95% CI: 1.22-1.64; P < 0.001). The same relationship was observed in hormone receptor-positive (HR+) (adjusted ORWC = 1.26; 95% CI: 1.02-1.57; P = 0.035, adjusted ORWHR = 1.41; 95% CI: 1.00-1.98; P = 0.051) and hormone receptor-negative (HR-) (adjusted ORWC = 1.44; 95% CI: 1.13-1.83; P = 0.003, adjusted ORWHR = 1.42; 95% CI: 0.95-2.13; P = 0.087) BCs. Prospective cohort studies indicated that high WC (adjusted RR = 1.12; 95% CI: 1.08-1.16; P < 0.001) and WHR (adjusted RR = 1.05; 95% CI: 1.018-1.09; P = 0.017) may increase BC risk. Subgroup analysis demonstrated a significant correlation during premenopausal (adjusted RR = 1.08; 95% CI: 1.02-1.14; P = 0.007) and postmenopausal (adjusted RR = 1.14; 95% CI: 1.10-1.19; P < 0.001) between BC and central obesity measured by WC, and WHR was significantly positively related to BC both premenopausal (adjusted RRpre = 1.04; 95% CI: 0.98-1.11; P = 0.169) and postmenopausal (adjusted RRpost = 1.04; 95% CI: 1.02-1.07; P = 0.002). Regarding molecular subtype, central obesity was significantly associated with HR+ (adjusted ORWC = 1.13; 95% CI: 1.07-1.19; P < 0.001, adjusted ORWHR = 1.03; 95% CI: 0.98-1.07; P = 0.244) and HR- BCs (adjusted ORWC =1.11; 95% CI: 0.99-1.24; P = 0.086, adjusted ORWHR =1.01; 95% CI: 0.91-1.13; P = 0.808). Our dose-response analysis revealed a J-shaped trend in the relationship between central obesity and BC (measured by WC and WHR) in case-control studies and an inverted J-shaped trend between BMI (during premenopausal) and BC in the prospective cohort.

Conclusion

Central obesity is a risk factor for premenopausal and postmenopausal BC, and WC and WHR may predict it. Regarding the BC subtype, central obesity is proven to be a risk of ER+ and ER- BCs. The dose-response analysis revealed that when BMI (during premenopausal) exceeded 23.40 kg/m2, the risk of BC began to decrease, and WC higher than 83.80 cm or WHR exceeded 0.78 could efficiently increase the BC risk.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022365788.

The relation between obesity and breast cancer risk in women by considering menstruation status and geographical variations: a systematic review and meta-analysis

Given the increase in the incidence of breast cancer during the past decades, several studies have investigated the effects of variables on breast cancer, especially obesity. This systematic review and meta-analysis aims to evaluate any effects of obesity on breast cancer risk in women, before and after menopause, and in different continents.All forms of relevant literature examining any association between obesity and breast cancer, including cohort, case-control, and cross-sectional studies, were identified in the PubMed, Scopus, EMBASE, and Web of Science databases from January 1, 1990 until January 13, 2023. Body mass index (BMI) > 30 was used to indicate obesity. Every type of breast cancer was examined as outcome factors. The quality of the papers was evaluated using the Newcastle-Ottawa scale checklist. The Egger and Begg test was used to evaluate publication bias. To assess any extra impact of each research on the final measurement, a sensitivity analysis was carried out.One hundred and two studies were included in this meta-analysis. Respectively, 48 and 67 studies reported associations between obesity and breast cancer in pre and post menopausal women. Combining all studies, the pooled OR of the association between obesity and breast cancer in pre-menopausal women was OR = 0.93 CI: (0.85-1.1), (I² = 65.4%), and for post-menopausal woman, OR = 1.26 CI: (1.19-1.34), (I² = 90.5%).Obesity has a protective role in breast cancer among pre-menopausal women, but this relationship is statistically significant only in European women. The chance of developing breast cancer increases in post-menopausal women who are obese. This relationship is significant among Asian, North American, African and European women.

Association Between Obesity and Circulating Tumor Cells in Early Breast Cancer Patients

BACKGROUND

Obesity and the presence of circulating tumor cells (CTCs) before and/or after chemotherapy are associated with poor outcome in breast cancer (BC) patients. The activation of oncogenic pathways in fatty tissue leads to cell proliferation, suggesting a possible link between obesity and CTCs.

MATERIALS AND METHODS

In the phase III SUCCESS A trial, 3754 patients with early BC were randomized to 3 cycles of fluorouracil, epirubicin and cyclophosphamide followed by 3 cycles of docetaxel with or without gemcitabine. Data of 1088 patients with CTC assessments (CellSearch-System; Menarini Silicon Biosystems, Italy) and body mass index (BMI) measurements both before and after chemotherapy were available. Patients were classified according to the WHO's international definitions as underweight, normal weight, overweight, or obese, and according to their weight-change during chemotherapy into a weight-loss group (> 5% decrease), stable-weight group (≤ 5% weight-change) or weight-gain group (>5% increase). Associations between CTC positivity and, BMI or weight-change group were analyzed using frequency-table methods.

RESULTS

At study entry, 47.4% patients were underweight or normal weight, 33.6% were overweight and 18.9% were obese. Before and after chemotherapy, CTCs were detected in 20.1% and 22.6% of patients, respectively. There was no association between CTC positivity and BMI before (P = 0.104) or after (P = 0.051) chemotherapy. Furthermore, there was no association between weight-change group and CTC status before/after chemotherapy (P = 0.332).

CONCLUSIONS

According to our analysis, the risk factors obesity and prevalence of CTCs are not associated and may represent independent prognostic factors.

Metabolic syndrome and breast cancer: a dangerous association for postmenopausal women

BACKGROUND

Breast cancer(BC) is the most common cancer in women worldwide, the relationship between metabolic syndrome(MetS) and BC needs to be better clarified. Today the early diagnosis of breast cancer(BC) is yet a challenging problem in clinical practice, so the evidence that a well identified population of postmenopausal women, affected by MetS, presents a high risk, of breast cancer occurrence, is useful for breast cancer prevention. Our study aims to assess the prevalence of metabolic syndrome, diagnosed according to current guidelines, in postmenopausal women with breast cancer, and its role as an independent risk factor.

RESULTS

MetS rate was significantly higher among women affected by BC:10.1%, 33 women, than CG:5.4%, 18 women, Chi-squared4.8,Odds ratio1.94,c.i.95%,p<0.02. Metabolic cardiomyopathy rate was significantly higher among women affected by BC:5.8%, 18 women, than CG:1.8%, 6 women, Chi-squared6.5,Odds ratio3.2,c.i.95%,p<0.01. Otherwise MetS rate without cardiomyopathy was higher among women affected by BC:4.8%, 15 women, than CG:3.4%, 11 women, but in a not statistically significant way, Chi-squared0.8,Odds ratio1.35,c.i.95%,p<0.36.

CONCLUSION

There was a significant relationship, in our population, between MetS and BC, adding evidence to this controversial association, the relationship was even tighter, when restricted to women affected by metabolic cardiomyopathy; otherwise it, restricted to women affected by MetS, without metabolic cardiomyopathy, was not statistically significant. Since the prevalence of MetS is increasing worldwide, just like the incidence of BC, an intervention is needed to improve physical activity and weight reduction to decrease the MetS rate.

Central Adiposity and Subsequent Risk of Breast Cancer by Menopause Status

BACKGROUND

Increased body mass index (BMI) is associated with higher postmenopausal breast cancer risk and lower premenopausal breast cancer risk. Less is known about the central adiposity-breast cancer risk association, particularly for tumor subtypes.

METHODS

We used prospective waist (WC) and hip circumference (HC) measures in the Nurses' Health Studies. We examined associations of WC, HC, and waist-to-hip ratio (WHR) with breast cancer independent of BMI, by menopausal status. Cox proportional hazards models estimated the hazard ratios (HRs) and 95% confidence intervals (CIs) adjusting for breast cancer risk factors, with and without BMI.

RESULTS

Adjusting for BMI, WC and HC were not associated, and WHR was positively associated with premenopausal breast cancer risk (WHR, quintile 5 vs 1: HRQ5vQ1, BMI-adjusted = 1.27, 95% CI = 1.04 to 1.54; Ptrend = .01), particularly for estrogen receptor-negative (ER-) and progesterone receptor-negative (PR-) and basal-like breast cancers. Premenopausal WC, HC, and WHR were not associated with postmenopausal breast cancer risk, with or without BMI adjustment. Postmenopausal WC, HC, and WHR were each positively associated with postmenopausal breast cancer (eg, WC HRQ5vsQ1 = 1.59, 95% CI = 1.36 to 1.86); after adjustment for BMI, only WC remained statistically significant (HRQ5vsQ1, BMI-adjusted = 1.38, 95% CI = 1.15 to 1.64; Ptrend = .002). In postmenopausal women, associations were stronger among never-users of hormone therapy and for ER+/PR+ breast cancers.

CONCLUSIONS

Central adiposity was positively associated with pre- and postmenopausal breast cancers independent of BMI. This suggests that mechanisms other than estrogen may also play a role in the relationship between central adiposity and breast cancer. Maintaining a healthy waist circumference may decrease pre- and postmenopausal breast cancer risk.

The role of immune dysfunction in obesity-associated cancer risk, progression, and metastasis

Obesity has been linked to an increased risk of and a worse prognosis for several types of cancer. A number of interrelated mediators contribute to obesity's pro-tumor effects, including chronic adipose inflammation and other perturbations of immune cell development and function. Here, we review studies examining the impact of obesity-induced immune dysfunction on cancer risk and progression. While the role of adipose tissue inflammation in obesity-associated cancer risk has been well characterized, the effects of obesity on immune cell infiltration and activity within the tumor microenvironment are not well studied. In this review, we aim to highlight the impact of both adipose-mediated inflammatory signaling and intratumoral immunosuppressive signaling in obesity-induced cancer risk, progression, and metastasis.

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.

Relationship Between Metabolic Syndrome and Postmenopausal Breast Cancer

INTRODUCTION

Metabolic syndrome is associated with an increased risk of diabetes mellitus (DM) and coronary heart disease. It may also be associated with a higher risk of some common cancers. The objective of this study was to determine the relationship between metabolic syndrome and breast cancer in postmenopausal women.

METHODS

We present a prospective cohort study of postmenopausal women. This cohort was divided into two groups: the «benign diagnosis group», including women who were studied after breast cancer screening; and the «malignant tumor group», including patients with breast cancer that had been diagnosed by biopsy. Age, weight, height, body mass index (BMI), abdominal perimeter, serum glucose, LDL, HDL and insulin levels were analyzed as variables under study. The HOMA-IR homeostatic model formula was used to assess insulin resistance. The differences were considered statistically significant when P<.05.

RESULTS

Two hundred women with a mean age of 61.5±9.6 (range: 37-93) were enrolled in the study, consisting of 150 (75%) patients with a benign diagnosis and 50 (25%) patients with a malignant tumor. BMI and abdominal perimeter were higher in the group with a malignant tumor (P<.05). The incidence of DM and metabolic syndrome was higher in the malignant tumor group (P<.005). In the malignant tumor group, much higher incidences correlated with fasting glycemic levels >100mg/dL, insulin levels >10mIU/L and HOMA-IR scores >2.7 (P<.05).

CONCLUSIONS

There is a relationship between metabolic syndrome and postmenopausal breast cancer. More studies are needed to establish methods for the prevention of breast cancer in women with metabolic syndrome.

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

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.

Thyroid hormones and breast cancer association according to menopausal status and body mass index

BACKGROUND

Thyroxine (T4) has been positively associated with tumor cell proliferation, while the effect of triiodothyronine (T3) on cell proliferation has not been well-established because it differs according to the type of cell line used. In Mexico, it has been reported that 14.5% of adult women have some type of thyroid dysfunction and abnormalities in thyroid function tests have been observed in a variety of non-thyroidal illnesses, including breast cancer (BC). These abnormalities might change with body mass index (BMI) because thyroid hormones are involved in the regulation of various metabolic pathways and probably by menopausal status because obesity has been negatively associated with BC in premenopausal women and has been positively associated with BC in postmenopausal women.

METHODS

To assess the association between serum thyroid hormone concentration (T4 and T3) and BC and the influence of obesity as an effect modifier of this relationship in premenopausal and postmenopausal women, we measured serum thyroid hormone and thyroid antibody levels in 682 patients with incident breast cancer (cases) and 731 controls, who participated in a population-based case-control study performed from 2004 to 2007 in three states of Mexico. We tested the association of total T4 (TT4) and total T3 (TT3) stratifying by menopausal status and body mass index (BMI), and adjusted for other health and demographic risk factors using logistic regressions models.

RESULTS

Higher serum total T4 (TT4) concentrations were associated with BC in both premenopausal (odds ratio (OR) per standard deviation = 5.98, 95% CI 3.01-11.90) and postmenopausal women (OR per standard deviation = 2.81, 95% CI 2.17-3.65). In premenopausal women, the effect of TT4 decreased as BMI increased while the opposite was observed in postmenopausal women. The significance of the effect modification was marginal (p = 0.059) in postmenopausal women and was not significant in premenopausal women (p = 0.22). Lower TT3 concentrations were associated with BC in both premenopausal and postmenopausal women and no effect modification was observed.

CONCLUSIONS

There is a strong association between BC and serum concentrations of TT3 and TT4; this needs to be further investigated to understand why it happens and how important it is to consider these alterations in treatment.

Body mass index had different effects on premenopausal and postmenopausal breast cancer risks: a dose-response meta-analysis with 3,318,796 subjects from 31 cohort studies

Background

There is sufficient evidence supporting a relationship between increased body mass index (BMI) and an increased risk for breast cancer among postmenopausal women. However, most studies have found a decreased risk for premenopausal breast cancer. This study was conducted to find out the different effects of BMI on the risk of breast cancer among premenopausal and postmenopausal women, and explore the potential factors that influence the associations.

Methods

A dose-response meta-analysis with 3,318,796 participants from 31 articles was conducted. Cohort studies that included BMI and corresponding breast cancer risk were selected through various databases including PubMed, Medline, Web of Science, the China National Knowledge Infrastructure (CNKI) and Chinese Scientific Journals (VIP). Random effects models were used for analyzing the data.

Results

The summary relative risks (RRs) were 1.33 (95%CI: 1.20–1.48) and 0.94(95%CI: 0.80–1.11) among postmenopausal and premenopausal women, respectively. The dose-response meta-analysis indicated a positive non-linear association between BMI and breast cancer risk among postmenopausal women, and compared to the mean level of the normal BMI category (21.5 kg/m²) the RR in total postmenopausal women were1.03 (95% CI: 1.02–1.05) per 1 kg/m² increment. However, no statistically significant association among total premenopausal women was detected. In subgroup analysis among European premenopausal women, the summary RR was 0.79(95%CI: 0.70–0.88). The non-linear relationship showed a negative non-linear association between BMI and breast cancer risk among European premenopausal women. When compared to the mean level of the normal BMI category, the RRs were 0.98 (95%CI: 0.96–1.00) per 1 kg/m² increment, respectively.

Conclusions

In line with previous studies BMI had different effects on pre-menopausal and postmenopausal breast cancer risk. However, contrary to previous studies, a high BMI was not associated with decreased risk in total pre-menopausal women. More research is needed to better understand these differences.

Electronic supplementary material

The online version of this article (10.1186/s12889-017-4953-9) contains supplementary material, which is available to authorized users.

Metabolic Syndrome and Breast Cancer Risk

Objective

The study was meant to estimate the prevalence of metabolic syndrome in patients with breast cancer and to establish its role as an independent risk factor on occurrence of breast cancer.

Materials and Methods

Fifty women aged between 40 and 80 years with breast cancer and fifty controls of similar age were assessed for metabolic syndrome prevalence and breast cancer risk factors, including age at menarche, reproductive status, live births, breastfeeding, and family history of breast cancer, age at diagnosis of breast cancer, body mass index, and metabolic syndrome parameters.

Results

Metabolic syndrome prevalence was found in 40.0% of breast cancer patients, and 18.0% of those in control group (P = 0.02). An independent and positive association was seen between metabolic syndrome and breast cancer risk (odds ratio = 3.037; 95% confidence interval 1.214-7.597).

Conclusions

Metabolic syndrome is more prevalent in breast cancer patients and is an independent risk factor for breast cancer.

Central obesity and risks of pre- and postmenopausal breast cancer: a dose-response meta-analysis of prospective studies

Epidemiologic evidence has shown inconsistent findings regarding the relationships between abdominal fatness, as measured by waist circumferences (WC) or waist-to-hip ratio (WHR), and risks of pre- and postmenopausal breast cancer (BC). A dose-response meta-analysis of prospective studies was conducted to address these issues. Potentially eligible studies were identified by searching PubMed and EMBASE databases, and by carefully reviewing the bibliographies of retrieved publications and related reviews. The summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated using a random-effects model. When the most fully adjusted RRs were combined, both WC (14 studies, RR _{per 10-cm increase}  = 1.06, 95% CI: 1.04-1.09, I²  = 29.9%) and WHR (15 studies, RR _{per 0.1-unit increase}  = 1.07, 95% CI: 1.01-1.14, I²  = 52.9%) were significantly positively associated with postmenopausal BC, but neither WC (eight studies, RR _{per 10-cm increase}  = 1.05, 95% CI: 0.99-1.10, I²  = 0%) nor WHR (11 studies, RR _{per 0.1-unit increase}  = 1.07, 95% CI: 0.95-1.21, I²  = 59.7%) were associated with premenopausal BC. The WHR-postmenopausal BC association lost statistical significance after correcting publication bias (RR _{per 0.1-unit increase}  = 1.06, 95% CI: 0.99-1.13). When considering BMI-adjusted RRs, WC was associated with both pre- (five studies, RR _{per 10-cm increase}  = 1.09, 95% CI: 1.02-1.16, I²  = 0%) and postmenopausal BC (seven studies, RR _{per 10-cm increase}  = 1.05, 95% CI: 1.02-1.08, I²  = 6.3%), whereas WHR was not associated with either pre- (seven studies, RR _{per 0.1-unit increase}  = 1.12, 95% CI: 0.94-1.34, I²  = 70.9%) or postmenopausal BC (eight studies, RR _{per 0.1-unit increase}  = 1.05, 95% CI: 0.98-1.13, I²  = 57.3%). Among non-current (former or never) users of hormone replacement therapy, the summary RR _{per 10-cm increase} of postmenopausal BC associated with WC was 1.08 (95% CI: 1.03-1.05, I²  = 69.2%, seven studies; BMI-adjusted RR = 1.05, 95% CI: 1.02-1.09, I²  = 22.8%, four studies). This meta-analysis indicates that central obesity measured by WC, but not by WHR, is associated with modestly increased risks of both pre- and postmenopausal BC independent of general obesity.

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

Purpose

We conducted a study to evaluate the relationship between body mass index (BMI) and the risk of breast cancer (BC) and outcome in a population of 14,684 women aged 55 to 69 years eligible to participate in the Mammography Screening Program (MSP) in the Province of Modena, Italy.

Methods

The study population was drawn from women who underwent mammography screening between 2004 and 2006 in the Province of Modena. Women were subdivided into obese, overweight, and normal-weight categories according to BMI and followed until July 31, 2010, to evaluate the BC incidence. The clinicopathological characteristics of BC were also evaluated in different groups of patients classified according to BMI. After BC diagnosis, patients were followed for a median period of 65 (range, 2–104) months. Second events (recurrences and second tumors) were recorded, and the 5-year event-free survival (EFS) was calculated.

Results

After a period of 73 months, 366 cases of BC were diagnosed. Compared with normal-weight women, obese women had a significantly higher incidence of BC (relative risk [RR], 1.32; p=0.040) (RR=1), larger tumors (27% of tumors were larger than T2 size), and more nodal involvement (38.5% of tumors were node-positive). Furthermore, a significantly higher rate of total events was seen in obese women compared with overweight and normal-weight patients, respectively (17.9% vs. 11.4% vs. 10.8%, p=0.032). The 5-year EFS was 89.0%, 89.0%, and 80.0% for normal-weight, overweight, and obese patients, respectively.

Conclusion

We observed a significantly higher risk of BC in obese women among those eligible to participate in the MSP in the Province of Modena. Finally, obese women had more second events and poorer EFS compared to nono bese women.

Apolipoproteins, lipids and risk of cancer

The epidemiological evidence for an obesity-cancer association is solid, whereas the association between obesity-associated lipoprotein levels and cancer is less evident. We investigated circulating levels of Apolipoprotein A1 (ApoA1), Apolipoprotein B (ApoB), LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) and association to risk of overall cancer and common cancer forms. The Malmö Diet and Cancer Study, a population-based prospective cohort study, enrolled 17,035 women and 11,063 men (1991-1996). Incident cancer cases were ascertained by record linkage with the Swedish Cancer Registry until end of follow-up, January 1, 2012. Baseline serum levels of ApoA1 and ApoB were analyzed for the entire cohort and HDL-C and LDL-C levels in 5,281 participants. Hazard ratios, with 95% confidence interval, were calculated using Cox's proportional hazards analysis. In the entire cohort, none of the exposures were related to overall cancer risk (HRadj ApoA1 = 0.98, 95%CI: 0.95,1.01; HRadj ApoB = 1.01, 95%CI: 0.98-1.04). Among men, ApoB was positively associated with cancer risk (HRadj ApoB = 1.06, 95%CI: 1.01,1.10). Female breast cancer risk was inversely associated with ApoB (HRadj = 0.92, 95%CI: 0.86,0.99). Among both genders, ApoA1 was inversely associated with lung cancer risk (HRadj = 0.88, 95%CI: 0.80,0.97), whereas high ApoB increased lung cancer risk (HRadj = 1.08, 95%CI: 0.99,1.18). Colorectal cancer risk was increased with high ApoB (HRadj = 1.08, 95%CI: 1.01,1.16) among both genders. Apolipoprotein levels were not associated with prostate cancer incidence. Circulating levels of apolipoproteins are associated with overall cancer risk in men and across both genders with breast, lung and colorectal cancer risk. Validation of these findings may facilitate future primary prevention strategies for cancer.

Can we improve breast cancer mortality in Okinawa? Consensus of the 7th Okinawa Breast Oncology Meeting

The rate of breast cancer mortality in Okinawa has gradually been increasing up to 2010. Now Okinawa has the second worst mortality rate in Japan, in part due to the enormous dietary changes resulting from the post-World War II US military occupation, high incidence of obesity, high non-optimal treatment rate, and low breast-cancer screening rate. To reduce breast cancer mortality in Okinawa, we established the Okinawa Breast Oncology Meeting (OBOM) in 2012. At the 7th OBOM held on January 10th, 2014, we discussed the breast cancer mortality in Okinawa focusing on lifestyle, breast cancer screening and optimal treatments. The Okinawan women who were overweight and/or obese during premenopausal and postmenopausal ages had a statistically significant higher risk of breast cancer development compared to those with non-overweight and/or obese women. The traditional diet of Okinawa consists of foods low in calories but rich in nutritional value. Therefore, we recommend Okinawan people not to forget the Okinawan traditional lifestyle, and to reduce their bodyweight to prevent breast cancer. One of the main goals of the OBOM is to raise breast cancer screening attendance rates to 50% (29.2% in 2010). We should standardize the quality control for breast cancer screening in Okinawa. It is important to continue enlightening the Okinawan population to receive optimal treatment. In addition, we are striving to establish systematic medical cooperation between the hospitals specializing in breast cancer treatment with rural hospitals. The OBOM group endeavors to contribute to the improvement of breast cancer mortality in Okinawa.

Height and Breast Cancer Risk: Evidence From Prospective Studies and Mendelian Randomization

BACKGROUND

Epidemiological studies have linked adult height with breast cancer risk in women. However, the magnitude of the association, particularly by subtypes of breast cancer, has not been established. Furthermore, the mechanisms of the association remain unclear.

METHODS

We performed a meta-analysis to investigate associations between height and breast cancer risk using data from 159 prospective cohorts totaling 5216302 women, including 113178 events. In a consortium with individual-level data from 46325 case patients and 42482 control patients, we conducted a Mendelian randomization analysis using a genetic score that comprised 168 height-associated variants as an instrument. This association was further evaluated in a second consortium using summary statistics data from 16003 case patients and 41335 control patients.

RESULTS

The pooled relative risk of breast cancer was 1.17 (95% confidence interval [CI] = 1.15 to 1.19) per 10cm increase in height in the meta-analysis of prospective studies. In Mendelian randomization analysis, the odds ratio of breast cancer per 10cm increase in genetically predicted height was 1.22 (95% CI = 1.13 to 1.32) in the first consortium and 1.21 (95% CI = 1.05 to 1.39) in the second consortium. The association was found in both premenopausal and postmenopausal women but restricted to hormone receptor-positive breast cancer. Analyses of height-associated variants identified eight new loci associated with breast cancer risk after adjusting for multiple comparisons, including three loci at 1q21.2, DNAJC27, and CCDC91 at genome-wide significance level P < 5×10(-8).

CONCLUSIONS

Our study provides strong evidence that adult height is a risk factor for breast cancer in women and certain genetic factors and biological pathways affecting adult height have an important role in the etiology of breast cancer.

Overall and central adiposity and breast cancer risk in the Sister Study

BACKGROUND

Greater body mass index (BMI), a measure of overall adiposity, is associated with a higher risk of postmenopausal breast cancer. The role of central adiposity, often measured by waist circumference, is less well understood, especially among premenopausal women. The objective of the current study was to examine multiple measures of adiposity in relation to breast cancer in a prospective cohort study.

METHODS

A total of 50,884 Sister Study cohort participants aged 35 to 74 years were enrolled from 2003 through 2009. Inclusion criteria for the cohort included having a sister previously diagnosed with breast cancer. Trained study personnel measured height, weight, and waist and hip circumference during a home visit and study participants completed a detailed questionnaire. Using Cox regression analysis, we estimated multivariable hazard ratios (HRs) and 95% confidence intervals (95% CIs) for breast cancer risk associated with adiposity measurements, considering tumor subtype and menopausal status.

RESULTS

In total, 2009 breast cancers were diagnosed during follow-up (mean = 5.4 years). Weight, BMI, waist circumference, and waist-to-hip ratio were found to be positively associated with overall breast cancer risk and HRs were greater among postmenopausal women, those with hormonally responsive tumors, and women who were not currently using postmenopausal hormones. In models that adjusted for BMI, waist circumference associations persisted among both postmenopausal women (81-88 cm vs ≤80 cm: HR = 1.16 [95% CI 1.01-1.35] and >88 cm vs ≤80 cm: HR = 1.30 [95% CI 1.10-1.54]) and premenopausal women (81-88 cm vs ≤80 cm: HR = 1.56 [95% CI 1.19-2.04] and >88 cm vs ≤80 cm: HR = 1.30 [95% CI 0.91-1.87]).

CONCLUSIONS

Findings from this large, prospective study with examiner-measured body size indicate that waist circumference is independently and positively associated with both premenopausal and postmenopausal breast cancer risk.

The integrative role of leptin, oestrogen and the insulin family in obesity-associated breast cancer: potential effects of exercise

Obesity is an established risk factor for postmenopausal breast cancer. The mechanisms through which obesity influences the development and progression of breast cancer are not fully elucidated; however, several factors such as increased oestrogen, concentrations of various members of the insulin family and inflammation that are associated with adiposity are purported to be important factors in this relationship. Emerging research has also begun to focus on the role of adipokines, (i.e. adipocyte secreted factors), in breast cancer. Leptin secretion is directly related to adiposity and is believed to promote breast cancer directly and independently, as well as through involvement with the oestrogen and insulin signalling pathways. As leptin is secreted from white adipose tissue, any intervention that reduces adiposity may be favourable. However, it is also important to consider that energy expenditure through exercise, independent of fat loss, may improve leptin regulation. The purpose of this narrative review was to explore the role of leptin in breast cancer development and progression, identify key interactions with oestrogen and the insulin family, and distinguish the potential effects of exercise on these interactions.

Body size throughout adult life influences postmenopausal breast cancer risk among hispanic women: the breast cancer health disparities study

BACKGROUND

Few studies have assessed the association of body size with postmenopausal breast cancer risk in Hispanic women. Findings are inconsistent and appear to contradict those reported for non-Hispanic white (NHW) women.

METHODS

We pooled interview and anthropometric data for 2,023 Hispanic and 2,384 NHW women from two U.S. population-based case-control studies. Using logistic regression analysis, we examined associations of overall and abdominal adiposity with risk of postmenopausal breast cancer defined by estrogen receptor (ER) and progesterone receptor (PR) status.

RESULTS

Weight gain was associated with increased risk of ER(+)PR(+) breast cancer in Hispanics not currently using menopausal hormone therapy (HT), but only among those with a low young-adult body mass index (BMI). In the subset of Hispanics with data on genetic ancestry, the association with weight gain was limited to women with lower Indigenous American ancestry. Young-adult BMI was inversely associated with both ER(+)PR(+) and ER(-)PR(-) breast cancers for both ethnicities combined, with similar, although nonsignificant, inverse trends in Hispanics and NHWs. Among all Hispanics, regardless of HT use, height was associated with risk of ER(-)PR(-) breast cancer and hip circumference with risk of breast cancer overall.

CONCLUSIONS

Body size throughout adult life is associated with breast cancer risk among postmenopausal Hispanic women, as has been reported for NHW women. Associations were specific for breast cancer subtypes defined by hormone receptor status.

IMPACT

Avoiding weight gain and maintaining a healthy weight are important strategies to reduce the risk of postmenopausal ER(+)PR(+) breast cancer, the most common breast cancer subtype.

Overall and abdominal adiposity and premenopausal breast cancer risk among hispanic women: the breast cancer health disparities study

BACKGROUND

Few studies in Hispanic women have examined the relation between adult body size and risk of premenopausal breast cancer defined by hormone receptor status.

METHODS

The Breast Cancer Health Disparities Study pooled interview and anthropometric data from two large U.S. population-based case-control studies. We examined associations of overall and abdominal adiposity with risk of estrogen receptor- and progesterone receptor-positive (ER(+)PR(+)) and -negative (ER(-)PR(-)) breast cancer in Hispanic and non-Hispanic White (NHW) women, calculating ORs and 95% confidence intervals.

RESULTS

Among Hispanics, risk of ER(+)PR(+) breast cancer was inversely associated with measures of overall adiposity, including young-adult and current body mass index (BMI). Risk was substantially reduced among those with high (above the median) young-adult BMI and current overweight or obesity. The findings for overall adiposity were similar for Hispanics and NHWs. In the subset of Hispanics with data on genetic ancestry, inverse associations of current BMI, and weight gain with ER(+)PR(+) breast cancer were limited to those with lower Indigenous American ancestry. For ER(-)PR(-) breast cancer, height was associated with increased risk, and young-adult BMI was associated with reduced risk. For all breast cancers combined, positive associations were seen for waist circumference, waist-to-hip ratio, and waist-to-height ratio in Hispanic women only.

CONCLUSIONS

Our findings of body size associations with specific breast cancer subtypes among premenopausal Hispanic women were similar to those reported for NHW women.

IMPACT

Adiposity throughout the premenopausal years has a major influence on breast cancer risk in Hispanic women.

Body mass index and risk of breast cancer: a nonlinear dose-response meta-analysis of prospective studies

The role of Body Mass Index (BMI) for Breast Cancer (BC) remains to be great interest for a long time. However, the precise effect of nonlinear dose-response for BMI and BC risk is still unclear. We conducted a dose-response meta-analysis to quantitatively assess the effect of BMI on BC risk. Twelve prospective studies with 4,699 cases identified among 426,199 participants and 25 studies of 22,809 cases identified among 1,155,110 participants in premenopausal and postmenopausal groups, respectively, were included in this meta-analysis. Significant non-linear dose-response (P < 0.001) association was identified between BMI and BC risk in postmenopausal women. Individuals with BMI of 25, 30, and 35 kg/m² yielded relative risks (RRs) of 1.02 [95% confidence interval (CI): 0.98–1.06], 1.12 (95% CI: 1.01–1.24), and 1.26 (95% CI: 1.07–1.50), respectively, when compared to the mean level of the normal BMI range. However, inverse result though not significant was observed in premenopausal women. In conclusion, the results of this meta-analysis highlighted that obesity contributed to increased BC risk in a nonlinear dose-response manner in postmenopausal women, and it is important to realize that body weight control may be a crucial process to reduce BC susceptibility.

Association of skirt size and postmenopausal breast cancer risk in older women: a cohort study within the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS)

OBJECTIVES

Several studies suggest that overall and central-obesity are associated with increased breast cancer (BC) risk in postmenopausal-women. However, there are no studies investigating changes of central obesity and BC. We report on the association of BC risk with self-reported skirt size (SS; waist-circumference proxy) changes between 20s and postmenopausal-age.

DESIGN

Prospective cohort-study.

SETTING

UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) involving the nine trial centres in England.

PARTICIPANTS

Postmenopausal-women aged >50 with no known history of BC prior to or on the day of completion of the study-entry questionnaire.

INTERVENTIONS

At recruitment and at study entry, women were asked to complete a questionnaire. Women were followed-up via 'flagging' at the NHS Information Centre in England and the Hospital Episode Statistics.

MAIN OUTCOME-MEASURE

Time to initial BC diagnosis.

RESULTS

Between 2 January 2005 and 1 July 2010, 92,834 UKCTOCS participants (median age 64.0) completed the study-entry questionnaire. During median follow-up of 3.19 years (25th-75th centile: 2.46-3.78), 1090 women developed BC. Model adjusted analysis for potential confounders showed body mass index (BMI) at recruitment to UKCTOCS (HR for a 5 unit change=1.076, 95% CI 1.012 to 1.136), current SS at study entry (HR=1.051; 95% CI 1.014 to 1.089) and change in SS per 10 years (CSS) (HR=1.330; 95% CI 1.121 to 1.579) were associated with increased BC risk but not SS at 25 (HR=1.006; 95% CI 0.958 to 1.056). CSS was the most predictive singe adiposity measure and further analysis including both CSS and BMI in the model revealed CSS remained significant (HR=1.266; 95% CI 1.041 to 1.538) but not BMI (HR=1.037; 95% CI 0.970 to 1.109).

CONCLUSIONS

CSS is associated with BC risk independent of BMI. A unit increase in UK SS (eg, 12-14) every 10-years between 25 and postmenopausal-age is associated with postmenopausal BC risk by 33%. Validation of these results could provide women with a simple and easy to understand message.

TRIAL REGISTRATION NUMBER

ISRCTN22488978.

Obesity, abdominal obesity and migraine: a cross-sectional analysis of ELSA-Brasil baseline data

BACKGROUND AND AIM

Most studies assessing the association between migraine and obesity have shown conflicting results. We aimed to evaluate the association between obesity and migraine in ELSA-Brasil, a cohort study of 15,105 individuals aged 35-74 years.

METHODS

We assessed migraine using a validated questionnaire based on International Headache Society criteria and anthropometric measurements using standard techniques. Migraine was categorized as daily and non-daily. World Health Organization criteria were used to categorize overweight, obesity and abdominal obesity (AbO). We performed a cross-sectional analysis using multivariate logistic regression models to study the association between migraine and obesity (body mass index (BMI) ≥ 30 kg/m(2)), compared to controls without migraine.

RESULTS

We found an association between daily migraine and obesity (odds ratio (OR) 1.86; 95% confidence interval (95% CI): 1.12-3.09). Although the presence of AbO was not associated with migraine, interaction models showed that the association between obesity and daily migraine remained strong only in the absence of AbO diagnosis, notably in individuals aged 35-49 years.

DISCUSSION

In our large sample of individuals aged 35 years or older, obesity, but not AbO, was associated with daily migraine. AbO influenced the association between BMI and daily migraine in migraineurs aged 35-49 years.

Prediabetes, diabetes, and risk of breast cancer: a case-control study

BACKGROUND AND AIMS

Although underlying mechanisms have been described to account for the association between prediabetes and diabetes with breast cancer, reported results have been inconsistent. We undertook this study to determine whether prediabetes and diabetes are risk factors for breast cancer in Mexican women with no family history of breast cancer in the mother, daughters, or sisters.

METHODS

A case-control study was carried out during 2011-2013. "Case" referred to patients with a histopathological diagnosis of breast cancer (incident and primary cases) (n = 240); "controls" were those with a BI-RADS 1 or 2 mammography result (n = 406). Categorization of prediabetes and diabetes was based on self-reporting or fasting glucose and glycated hemoglobin blood sampling results. Reproductive and sociodemographic data were collected by interview. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated using multivariate unconditional binary logistic regression analysis.

RESULTS

Prediabetes increased the risk of breast cancer in postmenopausal women (adjusted OR 2.08, 95% CI 1.10-3.96) as did diabetes (adjusted OR 2.85, 95% CI 1.55-5.26). A history of diabetes preceding breast cancer by ≥7 years and <7 years were both associated with an increased risk for breast cancer (adjusted OR 2.80, 95% CI 1.40-5.60 and 3.00, 95% CI 1.50-5.90, respectively).

CONCLUSIONS

This is the first study in Mexico evaluating prediabetes and diabetes as breast cancer risk factors in women with no first-degree relatives with breast cancer. Our findings suggest that women with prediabetes and diabetes should be considered a more vulnerable population for early breast cancer detection.

Associations of physical activity and inactivity with body tissue composition among healthy Polish women and women after mastectomy

The aim of the study is to determine the relationship between physical activity and body composition among healthy women and women who have had mastectomy. This is in order to establish whether physical activity of women after breast cancer treatment improves composition and distribution of body mass components to a degree which will allow to achieve the body composition of healthy women. Research material consists of anthropometric measurements (body height, weight) of women and bioelectric impedance analysis (BIA) of body composition (using Akern - BIA 101 composition analyzer). Intensity of activity was assessed using the Physical Activity International Questionnaire. The sample consisted of 76 healthy women (active 44.74%, inactive 55.26%) and 70 females after mastectomy (54.29% and 45.71%, respectively). Mean chronological age of women after mastectomy was 53.40 years, SD=7.55, and of the healthy ones 52.38 years SD=11.01). A significant difference in body composition was noted among active and inactive women after mastectomy; namely the active females had lower weight (by approximately 12 kg), body mass index (BMI), level of fat mass (by approximately 8%) and (by approximately 5%) total body water. The active healthy women had 6% less fat mass, almost 4% more body water and 6% more fat free mass. Programmed physical activity undertaken by women after mastectomy is recommended and produces good results in the form of reduction of excessive body fat tissue. Through physical activity these women are able to achieve the same level of fat mass as healthy women.

Higher incidence of premenopausal breast cancer in less developed countries; myth or truth?

Background

Fundamental etiologic differences have been suggested to cause earlier onset of breast cancer in less developed countries (LDCs) than in more developed countries (MDCs). We explored this hypothesis using world-wide breast cancer incidence data.

Methods

We compared international age-standardized incidence rates (ASR) of pre- (<50 years) and postmenopausal (≥50 years) breast cancers as well as temporal trends in ASRs of pre-and postmenopausal breast cancer among selected countries during 1975–2008. We used joinpoint log-linear regression analysis to estimate annual percent changes (APC) for premenopausal and postmenopausal breast cancer in the northern Europe and in Black and White women population in the US.

Results

Premenopausal breast cancers comprised a substantially higher proportion of all incident breast cancers in LDCs (average 47.3%) compared to MDCs (average 18.5%). However, the ASR of premenopausal breast cancer was consistently higher in MDCs (29.4/100,000) than LDCs (12.8/100,000). The ASR of postmenopausal cancer was about five-fold higher in the MDCs (307.6/100,000) than the LDCs (65.4/100,000). The APC of breast cancer in Denmark was substantially higher in postmenopausal (1.33%) than premenopausal cancer (0.98%). Higher incidence of breast cancer among the white than black women in the US was pertained only to the postmenopausal cancer.

Conclusion

The substantial and consistent lower age-specific incidence of breast cancer in LDCs than in MDCs contradicts the theory of earlier onset. Demographic differences with fewer old women in LDCs and lower prevalence of risk factors of postmenopausal cancer are the most likely explanation to the lower mean age at diagnosis in these countries.

Triple-negative breast cancer risk in women is defined by the defect of estrogen signaling: preventive and therapeutic implications

Epidemiologic studies strongly support that triple-negative breast cancers (TNBCs) may be distinct entities as compared with estrogen receptor (ER)+ tumors, suggesting that the etiologic factors, clinical characteristics, and therapeutic possibilities may vary by molecular subtypes. Many investigations propose that reproductive factors and exogenous hormone use differently or even quite inversely affect the risk of TNBCs and ER+ cancers. Controversies concerning the exact role of even the same risk factor in TNBC development justify that the biological mechanisms behind the initiation of both TNBCs and non-TNBCs are completely obscure. To arrive at a comprehensive understanding of the etiology of different breast cancer subtypes, we should also reconsider our traditional concepts and beliefs regarding cancer risk factors. Malignancies are multicausal, but the disturbance of proper estrogen signaling seems to be a crucial risk factor for the development of mammary cancers. The grade of defect in metabolic and hormonal equilibrium is directly associated with TNBC risk for women during their whole life. Inverse impact of menopausal status or parity on the development of ER+ and ER− breast cancers may not be possible; these controversial results derive from the misinterpretation of percentage-based statistical evaluations. Exogenous or parity-associated excessive estrogen supply is suppressive against breast cancer, though the lower the ER expression of tumors, the weaker the anticancer capacity. In women, the most important preventive strategy against breast cancers – included TNBCs – is the strict control and maintenance of hormonal equilibrium from early adolescence through the whole lifetime, particularly during the periods of great hormonal changes.

Evaluating the Relationship between Body Size and Body Shape with the Risk of Breast Cancer

OBJECTIVE

This study aims to determine the relationship between body size and body shape with the risk of breast cancer.

METHODS

In this case control study, 480 women participated (240 women with breast cancer in case group and 240 healthy women in control group). After completing the interview form, the weight, height, waist circumference, hip circumference and breast size, were measured. The data were analyzed using statistical test by SPSS11.5.

RESULTS

The present study showed that the mean of hip circumference were significantly different in both groups (p=0.036). The size of the breast was statistically significant between the two groups. Thyroid type, one of the body shapes, was more seen in the case group than control group (p<0.001).

CONCLUSION

This study revealed that the risk of breast cancer increases with increased hip circumference. In addition, the results indicate that body shape may be a useful predictor in determining the risk of breast cancer. More studies should be designed to address this subject.

Circulatory estrogen level protects against breast cancer in obese women

Literary data suggest apparently ambiguous interaction between menopausal status and obesity-associated breast cancer risk based on the principle of the carcinogenic capacity of estrogen. Before menopause, breast cancer incidence is relatively low and adiposity is erroneously regarded as a protective factor against this tumor conferred by the obesity associated defective estrogen-synthesis. By contrast, in postmenopausal cases, obesity presents a strong risk factor for breast cancer being mistakenly attributed to the presumed excessive estrogen-production of their adipose-tissue mass. Obesity is associated with dysmetabolism and endangers the healthy equilibrium of sexual hormone-production and regular menstrual cycles in women, which are the prerequisites not only for reproductive capacity but also for somatic health. At the same time, literary data support that anovulatory infertility is a very strong risk for breast cancer in young women either with or without obesity. In the majority of premenopausal women, obesity associated insulin resistance is moderate and may be counteracted by their preserved circulatory estrogen level. Consequently, it is not obesity but rather the still sufficient estrogen-level, which may be protective against breast cancer in young adult females. In obese older women, never using hormone replacement therapy (HRT) the breast cancer risk is high, which is associated with their continuous estrogen loss and increasing insulin-resistance. By contrast, obese postmenopausal women using HRT, have a decreased risk for breast cancer as the protective effect of estrogen-substitution may counteract to their obesity associated systemic alterations. The revealed inverse correlation between circulatory estrogen-level and breast cancer risk in obese women should advance our understanding of breast cancer etiology and promotes primary prevention measures. New patents recommend various methods for the prevention and treatment of obesity-related systemic disorders and the associated breast cancer.

The biology of leptin and its implications in breast cancer: a general view

Obesity is a world health problem that increases the risk for developing type 2 diabetes, cardiovascular disease, fatty liver, and some types of cancer. In postmenopausal women, it represents an important risk factor for the development of breast cancer (BC). Leptin is an adipokine that is secreted by fatty tissue, and high leptin levels are observed both in mouse models of obesity and in obese subjects. High levels of leptin promote the proliferation and progression of various types of cancer, including BC. This review provides a general overview of the biology of leptin, important laboratory studies, and animal and clinical models that have provided evidence for an active role of leptin in the proliferation, progression, and survival of mammary tumors. Finally, this review addresses the most recent studies on the use of leptin receptor antagonists as a novel therapeutic treatment for BC.

Obesity, diabetes mellitus, and the risk of female breast cancer in Eastern China

Background

This study was designed to explore the relationship between obesity, diabetes mellitus (DM), and female breast cancer in Eastern China.

Methods

A 1:3 matched case–control study was carried out, comprising 123 women with breast cancer and 369 controls. All of the 492 subjects were selected from a previous epidemiological survey of 122,058 women in Eastern China.

Results

There were significant differences between the case and control groups in waist circumference and body mass index (BMI), but not in waist to hip ratio or hip circumference. There was a significant difference between the two groups in BMI for post-menopausal women, and a significant difference in waist circumference for pre-menopausal women. After adjustment for other factors, BMI was still significantly associated with breast cancer (odds ratio (OR) = 1.58, 95% confidence interval (CI) 1.14 to 2.19). DM was significantly associated with breast cancer (OR = 3.35, 95% CI 1.02 to 11.01) in the univariate analysis but not in the multivariate analysis (P = 0.059).

Conclusions

Obesity might be a risk factor for female breast cancer. We found different strengths of association for women with different menopausal status when we examined the relationship between obesity and breast cancer. The association between DM and female breast cancer should be further confirmed with larger sample sizes.

Effect of body mass index on breast cancer during premenopausal and postmenopausal periods: a meta-analysis

OBJECTIVE

There is no universal consensus on the relationship between body mass index (BMI) and breast cancer. This meta-analysis was conducted to estimate the overall effect of overweight and obesity on breast cancer risk during pre- and post-menopausal period.

DATA SOURCES

All major electronic databases were searched until April 2012 including Web of Knowledge, Medline, Scopus, and ScienceDirect. Furthermore, the reference lists and related scientific conference databases were searched.

REVIEW METHODS

All prospective cohort and case-control studies investigating the association between BMI and breast cancer were retrieved irrespective of publication date and language. Women were assessed irrespective of age, race and marital status. The exposure of interest was BMI. The primary outcome of interest was all kinds of breast cancers confirmed pathologically. Study quality was assessed using the checklist of STROBE. Study selection and data extraction were performed by two authors separately. The effect measure of choice was risk ratio (RR(i)) and rate ratio (RR(a)) for cohort studies and odds ratio (OR) in case-control studies.

RESULTS

Of 9163 retrieved studies, 50 studies were included in meta-analysis including 15 cohort studies involving 2,104,203 subjects and 3,414,806 person-years and 35 case-control studies involving 71,216 subjects. There was an inverse but non-significant correlation between BMI and breast cancer risk during premenopausal period: OR = 0.93 (95% CI 0.86, 1.02); RR(i) = 0.97 (95% CI 0.82, 1.16); and RR(a) = 0.99 (95% CI 0.94, 1.05), but a direct and significant correlation during postmenopausal period: OR = 1.15 (95% CI 1.07, 1.24); RR(i) = 1.16 (95% CI 1.08, 1.25); and RR(a) = 0.98 (95% CI 0.88, 1.09).

CONCLUSION

The results of this meta-analysis showed that body mass index has no significant effect on the incidence of breast cancer during premenopausal period. On the other hand, overweight and obesity may have a minimal effect on breast cancer, although significant, but really small and not clinically so important.

Cardiometabolic factors and breast cancer risk in U.S. black women

Previous studies have suggested that metabolic syndrome may be associated with an increased risk of breast cancer, particularly in postmenopausal women, but U.S. black women have not been assessed. We examined the associations of abdominal obesity, type 2 diabetes, hypertension, and high cholesterol individually and in combination with breast cancer incidence in the Black Women's Health Study. By means of Cox regression models, we estimated incidence rate ratios (IRR) and 95 % confidence intervals (CI) for the associations of baseline and time-dependent values of self-reported abdominal obesity, type 2 diabetes, hypertension, and high cholesterol with breast cancer incidence. During 516,452 person years of follow-up (mean years = 10.5; standard deviation = 2.9) from 1995 to 2007, 1,228 breast cancer cases were identified. After adjustment for age, education, body mass index at age 18, physical activity, and individual cardiometabolic factors, neither individual nor combinations of cardiometabolic factors were associated with breast cancer incidence overall; the multivariable IRR was 1.04 (95 % CI 0.86-1.25) for the combination of ≥3 factors relative to the absence of all factors, and 1.17 (0.85-1.60) for having all four factors. Among postmenopausal women, however, the comparable IRRs were 1.23 (0.93-1.62) and 1.63 (1.12-2.37), respectively. Our findings provide some support for an association between cardiometabolic factors and breast cancer incidence among postmenopausal U.S. black women.

Age of 40 years or younger is an independent risk factor for locoregional failure in early breast cancer: a single-institutional analysis in saudi arabia

Background. This study was undertaken to evaluate the impact of prognostic factors on the locoregional failure-free survival of early breast cancer patients. Methods. In this single-institutional study, 213 breast cancer patients were retrospectively analysed. Fifty-five of 213 patients were ≤40 years of age at diagnosis. The impact of patient- or treatment-related factors on the locoregional failure-free survival was assessed using the Kaplan-Meier method. The simultaneous impact of factors on the locoregional failure-free survival was assessed using the Cox proportional hazards regression analysis. Results. The median follow-up time of the censored patients was 22 months (mean 28 months, range 3-92 months). On univariate analysis, statistically significant factors for the locoregional failure-free survival were the age (≤40 versus >40 years), T stage (Tis, T0-2 versus T3-4), molecular tumor type (luminal A versus luminal B, Her2neu overexpression, or triple negative), and lymphovascular status (LV0 versus LV1). On multivariate analysis, age and T stage remained statistically significant. Conclusions. Being 40 years or younger has a statistically significant independent adverse impact on the locoregional failure-free survival of patients with early breast cancer.

Body fat distribution and breast cancer risk: findings from the Nigerian breast cancer study

PURPOSE

The relationship between overall obesity and breast cancer risk has been well recognized, but the role of central obesity in breast cancer development is uncertain.

METHODS

Between 1998 and 2009, 1,233 invasive breast cancer cases and 1,101 community controls were recruited into the Nigerian Breast Cancer Study at Ibadan, Nigeria. Logistic regressions were used to calculate multivariate odds ratio (OR) and 95% confidence intervals (CI), adjusting for age, body mass index (BMI), and other known risk factors for breast cancer.

RESULTS

The OR for the highest quartile group of waist circumference relative to the lowest was 2.39 (95% CI, 1.59-3.60; P-trend < 0.001). Comparing women with waist/hip ratio (WHR) in the lowest quartile group, the OR for women in the highest quartile category was 2.15 (95% CI, 1.61-2.85; P-trend < 0.001). An inverse association was observed between hip circumference and breast cancer, with an OR of 0.36 for the highest quartile (95% CI, 0.24-0.55; P-trend < 0.001). The effects of these three measures existed in both pre- and postmenopausal women. Of note, we found a significant interaction between WHR and BMI (P-interaction = 0.016): the OR comparing the highest to the lowest WHR quartile was 2.81 (95% CI, 1.90-4.16) for women with BMI < 25 kg/m2 and 1.70 (95% CI, 1.11-2.61) for women with BMI ≥ 25 kg/m2.

CONCLUSIONS

These results suggest that central adiposity, measured by waist circumference and waist/hip ratio, was an important risk factor for breast cancer in Nigerian women, and the effect of central adiposity was strong in normal-weight women.

Overweight, obesity, diabetes, and risk of breast cancer: interlocking pieces of the puzzle

We considered epidemiological data on overweight, diabetes, insulin, and breast cancer. Overweight is inversely related to premenopausal breast cancer, but there is definite evidence that, as compared with normal weight women, the relative risk (RR) for postmenopausal breast cancer is around 1.5 for overweight women and >2 for obese women, and that the association is stronger in elderly women. Overweight and obesity are strongly related to diabetes. Diabetes is associated with postmenopausal breast cancer, too, with summary RRs from meta-analyses of 1.15-1.20, but not with premenopausal breast cancer (RR, 0.9). There is no consistent evidence that fasting insulin is related to breast cancer risk. Thus, although overweight and obesity are strongly related to postmenopausal breast cancer, diabetes is only moderately related to it. Given the extent of the association, and the likely residual confounding by overweight, inference on causality for the diabetes-breast cancer relation remains open to discussion.

A review of body size and breast cancer risk in Hispanic and African American women

Obesity is an epidemic in the United States, especially among Hispanics and African Americans. Studies of obesity and breast cancer risk have been conducted primarily in non-Hispanic whites. There have been few studies of the association between body mass index (BMI) or weight gain and the risk of breast cancer in minorities, and the results have been inconsistent. Because most studies are conducted primarily in non-Hispanic whites, the etiology of breast cancer in minorities is not well understood. The authors of the current report reviewed the literature on the association between obesity, weight, and weight gain and breast cancer in minorities using a combination of the Medical Subject Heading (MeSH) terms "obesity," "body mass index," "weight," "weight gain," "Hispanic," and "African American." Only publications in English and with both risk estimates and 95% confidence intervals were considered. Forty-five studies of body size and breast cancer risk in non-Hispanic whites were identified. After an exhaustive search of the literature, only 3 studies of body size and breast cancer were conducted in Hispanic women were identified, and only 8 such studies in African American women were identified. The results were inconsistent in both race/ethnicity groups, with studies reporting positive, inverse, and null results. Thus, as obesity rates among Hispanics and African Americans continue to rise, there is an urgent need to identify the roles that both obesity and adult weight gain play in the development of breast cancer in these minorities. Additional studies are needed to provide more understanding of the etiology of this disease and to explain some of the disparities in incidence and mortality.

Distribuição da gordura corporal e câncer de mama: um estudo de caso-controle no Sul do Brasil

O presente estudo tem como objetivo verificar a associação entre a distribuição da gordura corporal e o câncer de mama em mulheres do Rio Grande do Sul. Para este estudo, utilizou-se um delineamento de caso-controle, no qual foram avaliadas cem mulheres com diagnóstico histopatológico de câncer de mama em comparação com o grupo controle ambulatorial (400 mulheres) durante os meses de janeiro a outubro de 2005. As variáveis antropométricas coletadas foram: massa corporal (kg), estatura, circunferência da cintura (CC) e perímetro do quadril. Não foi encontrada associação entre o índice de massa corporal (IMC) e a razão cintura/quadril (RCQ) com ocorrência de câncer de mama. Já para CC, observou-se que mulheres com essa medida elevada (> 88 cm) apresentam 2,08 vezes mais chance de desenvolver a doença do que aquelas com as medidas normais ou moderadas (< 80 cm-87 cm). Quando essas mulheres foram agrupadas por estado menopausal (pré e pós) e variáveis antropométricas, somente a CC apresentou associação OR ajustado=3,15. Conclusão: acúmulo de gordura na parte superior do corpo (CC > 88 cm) é um preditor de câncer de mama especialmente em mulheres pré-menopausa.

Body fat distribution and risk of premenopausal breast cancer in the Nurses' Health Study II

Body mass index is inversely associated with risk of premenopausal breast cancer, but the underlying mechanisms for this association are poorly understood. Abdominal adiposity is associated with metabolic and hormonal changes, many of which have been associated with the risk of premenopausal breast cancer. We investigated the association between body fat distribution, assessed in 1993 by self-reported waist circumference, hip circumference, and waist to hip ratio, and the incidence of premenopausal breast cancer in the Nurses' Health Study II. Cox proportional hazards regression models were used to calculate hazard ratios and 95% confidence intervals (CIs). Statistical tests were two-sided. During 426,164 person-years of follow-up from 1993 to 2005, 620 cases of breast cancer were diagnosed among 45,799 women. Hormone receptor status information was available for 84% of the breast cancers. The age-standardized incidence rates of breast cancer were 131 per 100,000 person-years among those in the lowest quintile of waist circumference and 136 per 100,000 person-years among those in the highest quintile. No statistically significant associations were found between waist circumference, hip circumference, or the waist to hip ratio and risk of breast cancer. However, each of the three body fat distribution measures was statistically significantly associated with greater incidence of estrogen receptor (ER)-negative breast cancer. The multivariable-adjusted hazard ratios of ER-negative breast cancer for the highest vs the lowest quintile of each body fat distribution measure were 2.75 (95% CI = 1.15 to 6.54; P(trend) = .05) for waist circumference, 2.40 (95% CI = 0.95 to 6.08; P(trend) = .26) for hip circumference, and 1.95 (95% CI = 1.10 to 3.46; P(trend) = .01) for waist to hip ratio. Our findings suggest that body fat distribution does not play an important role in the overall incidence of premenopausal breast cancer but is associated with an increased risk for ER-negative breast cancer.

Body mass index and waist circumference are predictor biomarkers of breast cancer risk in Iranian women

Both obesity and breast cancer incidence increased dramatically during two recent decades in a rapidly changing society in northern Iran. In this study, we examined the ability of body mass index (BMI) and waist circumference (WC) as predictor biomarkers of breast cancer risk in Iranian women. In a case-control study of 100 new cases of histological confirmed breast cancer and 200 age-matched controls, in Babol, we measured weight, height, waist and hip circumference at time of diagnosis with standard methods. The data of demographic, characteristics, reproductive and lifestyle factors were collected by interview. We used both regression and receiver operator characteristics (ROC) analysis to estimate the predictive ability of BMI and WC for breast cancer as estimated by area under the curve (AUC). The results showed a significant difference in the mean of weight, BMI and WC between patients and controls in pre- and postmenopausal women (P<0.001). While after adjusting for BMI, no longer an association between WC and breast cancer was found. The overall accuracy of observed BMI and WC were 0.79 (95% CI: 0.74-0.84) and 0.68 (95% CI: 0.61-0.74), respectively. The accuracy of BMI and WC were 0.82 (95% CI: 0.76-0.89), 0.75(0.67-0.83) for premenopausal and 0.77(0.68-0.85), 0.60 (0.50-0.71) for postmenopausal women, respectively. BMI and WC are predictor biomarkers of breast cancer risk in both pre- and postmenopausal Iranian women while after adjusting for BMI, no longer an association between WC and breast cancer was observed. These findings imply to perform breast cancer screening program in women with a higher BMI and WC.

The modifying effect of social class on the relationship between body mass index and breast cancer incidence

OBJECTIVES

We sought to determine whether social class modifies the effect of BMI on breast cancer incidence.

METHODS

Participants included 5642 postmenopausal White women recruited in 1989 to CLUE II, a prospective cohort study in Washington County, Maryland. We obtained exposure data from CLUE II and the 1990 US Census. We used survival and random-effects Cox proportional hazards analyses to determine the association of social class and BMI with breast cancer incidence.

RESULTS

Education was independently associated with increased risk of breast cancer incidence (hazard ratio [HR]=1.06; 95% confidence interval [CI]=1.01, 1.11; P<.05); contextual measures of social class were not. Education modified the effect of BMI at age 21 years (HR=0.98; 95% CI=0.97, 0.99); area-level social class modified the effect of BMI at baseline (HR=0.97; 95% CI=0.94, 0.99) and BMI change (HR=0.98; 95% CI=0.95, 1.00). Subpopulation analyses that were adjusted for hormone use, parity, and breast-feeding found similar effects.

CONCLUSIONS

Social class moderates the influence of body size on breast cancer incidence. Public health efforts, therefore, should advocate for policies that improve social conditions to decrease the burden of breast cancer.

Obesity, body fat distribution and breast cancer

Abstract Strong epidemiological data exists implicating anthropometric risk factors in breast cancer aetiology. In premenopausal women the risk of breast cancer increases with increased height, yet decreases with increasing weight and BMI. Although the evidence is not strong, a counter-intuitive positive relationship between central adiposity and premenopausal breast cancer risk is emerging. In post-menopausal women an increased risk in breast cancer has been found for all anthropometric measures: height, weight, BMI, measures of central adiposity (waist:hip ratio and waist circumference) and weight gain, with breast size being a possible additional risk factor. Weight loss as a strategy for reducing breast cancer risk seems to offer a viable prophylaxis in obese post-menopausal women, although data are limited. The evidence for anthropometric measures in relation to breast cancer risk is consistently stronger for post-menopausal women compared with premenopausal women and seems to be dependent on age. A number of possible biological mechanisms have been offered to explain the link between breast cancer risk and anthropometric measures. It has been hypothesised that obesity, especially central fat deposits, linked to insulin resistance, increases circulating hormones such as oestrogens, androgens, insulin, insulin-like growth factor-1 (IGF-1), and decreased levels of hormone-binding proteins such as steroid hormone-binding globulin and IGF-1 binding protein-1. Thus there are resulting increased concentrations of bioavailable sex hormones, which have been linked to increased breast cancer risk. As obesity is an important modifiable risk factor, which has been linked to increased post-menopausal breast cancer, public health recommendations to maintain ideal weight throughout life are warranted.

The breast cancer and the environment research centers: transdisciplinary research on the role of the environment in breast cancer etiology

OBJECTIVES

We introduce and describe the Breast Cancer and the Environment Research Centers (BCERC), a research network with a transdisciplinary approach to elucidating the role of environmental factors in pubertal development as a window on breast cancer etiology. We describe the organization of four national centers integrated into the BCERC network.

DATA SOURCES

Investigators use a common conceptual framework based on multiple levels of biologic, behavioral, and social organization across the life span. The approach connects basic biologic studies with rodent models and tissue culture systems, a coordinated multicenter epidemiologic cohort study of prepubertal girls, and the integration of community members of breast cancer advocates as key members of the research team to comprise the network.

DATA EXTRACTION

Relevant literature is reviewed that describes current knowledge across levels of organization. Individual research questions and hypotheses in BCERC are driven by gaps in our knowledge that are presented at genetic, metabolic, cellular, individual, and environmental (physical and social) levels.

DATA SYNTHESIS

As data collection on the cohort, animal experiments, and analyses proceed, results will be synthesized through a transdisciplinary approach.

CONCLUSION

Center investigators are addressing a large number of specific research questions related to early pubertal onset, which is an established risk factor for breast cancer. BCERC research findings aimed at the primary prevention of breast cancer will be disseminated to the scientific community and to the public by breast cancer advocates, who have been integral members of the research process from its inception.

Risk factors for breast cancer in Pakistani women aged less than 45 years

BACKGROUND

There has been an increase in the incidence of breast cancer in previously low-risk Asian countries. It is important to identify the risk factors for Asian women, as little information currently exists for this population.

AIM

The objective of the study was to determine risk factors for breast cancer among Pakistani women.

SUBJECTS AND METHODS

498 cases younger than 45 years were interviewed from 1 July 1997 to 31 December 1998 at two major cancer hospitals. Age-matched population-based controls were selected from two cities and two villages to represent urban and rural areas. For the variables under study, cases and controls were compared by t-test. Conditional multiple logistic regression models were applied to the data set.

RESULTS

Women with BMI >or= 30, with a family history of breast cancer and who were parous were at increased risk. Among parous women risk factors included BMI >or= 30, being in a consanguineous marriage, later age at menarche, later age at first full-term pregnancy, high parity and a history of abortion.

CONCLUSION

The risk factors identified for Pakistani women below 45 years were similar to those observed in other studies. However, obesity in pre-menopausal women and late menarche were not protective and consanguinity was identified as a risk.