Measures of adiposity and risk of breast cancer in older postmenopausal women

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.

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.

Obesity and breast cancer risk for pre- and postmenopausal women among over 6 million Korean women

PURPOSE

To examine the association between obesity measured by body mass index (BMI) and waist circumference (WC) according to menopausal status in Korean women.

METHODS

We identified 6,467,388 women, using the Korean National Health Insurance System Cohort. Cox-proportional hazard models were used to generate adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for breast cancer risk in relation to BMI and WC.

RESULTS

In postmenopausal women, the risk of breast cancer increased with BMI. Compared to women with a BMI of 18.5-23 kg/m two, the risk of invasive breast cancer was lower in patients with BMI < 18.5 (aHR 0.82, 95% CI 0.75-0.89), while it increased linearly in those with BMI 23-25 (1.11, 1.08-1.14), BMI 25-30 (1.28, 1.25-1.32), and BMI ≥ 30 (1.54,1.47-1.62). In contrast, the risk of breast cancer decreased with BMI in premenopausal women. Compared to women with a BMI of 18.5-23, the risk of IBC was similar in those with a BMI < 18.5 (1.02, 0.94-1.11) and BMI 23-25 (1.01, 0.97-1.05), but was significantly lower in those with a BMI 25-30 (0.95, 0.91-0.98) and BMI ≥ 30 (0.90, 0.82-0.98). A relative increase with BMI was less profound for carcinoma in situ in postmenopausal women, and a relative decrease was more profound in premenopausal women. An analysis using WC showed almost identical results.

CONCLUSIONS

There was a positive relationship between obesity and breast cancer in postmenopausal women, and an inverse association in premenopausal women.

The association between DXA-derived body fat measures and breast cancer risk among postmenopausal women in the Women's Health Initiative

Background

Most studies demonstrating an association between excess adiposity and postmenopausal breast cancer have used anthropometric measures, particularly body mass index (BMI). However, more direct body fat measures may more accurately determine the relationship between body fat distribution and breast cancer risk.

Methods

Cox proportional hazards regression models were created to examine the associations of dual‐energy x‐ray absorptiometry (DXA) body fat measures (at baseline and during follow‐up) with breast cancer risk among 10 931 postmenopausal women from the Women's Health Initiative cohort. A total of 639 incident invasive breast cancer cases (including 484 estrogen receptor positive (ER+) cases) were ascertained after a median follow‐up of 15.0 years.

Results

Excess whole body fat mass and trunk fat mass were positively associated with risk invasive breast cancer risk. These associations persisted even after additional adjustment for standard anthropometric measures. In time‐dependent analyses, we observed that both whole body fat mass and trunk fat mass, in the highest versus lowest category, were associated with a doubling of risk of invasive breast cancer overall (HR: 2.17; 95% CI: 1.54‐3.05 and 2.20; 1.55‐3.14, respectively) and of ER+ breast cancer (2.05; 1.37‐3.05 and 2.03; 1.34‐3.07, respectively). The remaining DXA measures were also positively associated with breast cancer risk in baseline and time‐dependent analyses.

Conclusion

These findings suggest that DXA‐derived body fat measures are positively associated with breast cancer risk after adjustment for BMI and other conventional breast cancer risk factors.

Untapped "-omics": the microbial metagenome, estrobolome, and their influence on the development of breast cancer and response to treatment

With the advent of next generation sequencing technologies, there is an increasingly complex understanding of the role of gastrointestinal and local breast microbial dysbiosis in breast cancer. In this review, we summarize the current understanding of the microbiome's role in breast carcinogenesis, discussing modifiable risk factors that may affect breast cancer risk by inducing dysbiosis as well as recent sequencing data illustrating breast cancer subtype-specific differences in local breast tissue microbiota. We outline how the 'estrobolome,' the aggregate of estrogen-metabolizing enteric bacterial genes, may affect the risk of developing postmenopausal estrogen receptor-positive breast cancer. We also discuss the microbiome's potent capacity for anticancer therapy activation and deactivation, an important attribute of the gastrointestinal microbiome that has yet to be harnessed clinically.

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.

The association between fat mass and the risk of breast cancer: A systematic review and meta-analysis

BACKGROUND & AIMS

Several cohort and case-control studies examined the association between fat mass (FM) and the risk of breast cancer; however, findings are conflicting. The purpose of the present study was to systematically review this association and conducted a meta-analysis, if possible.

METHOD

A systematic search of PubMed/Medline, Scopus, Web of Science and Embase databases was conducted for cohort and case-control studies, between January 2000 and 31 March 2018 with no language limitations. Multivariate adjusted relative risk (RR) estimates with 95% confidence intervals (CI) for each category of FM were pooled to examine the association.

RESULTS

Finally, 12 papers were considered for quantitative synthesis. The pooled RR for the highest vs. the lowest FM (%) of cohort studies was 1.44 (95% CI: 1.33, 1.56; I²: 63.3%, p = 0.008). The overall effect size for adjusted case-control studies showed no significant association (1.49, 95% CI: 0.77, 2.90; I²: 93.2%; p = 0.001). After stratification by menopause, it was revealed that the association between FM and the risk of breast cancer in post menopausal women (2.29, 95% CI: 1.12, 4.68; I²: 92%, p = 0.0001) was significant, while there was no significant association in pre-menopausal women (0.68, 95% CI: 0.18, 2.58; I²: 81.3%; p = 0.02).

CONCLUSION

Cohort studies showed that higher FM is positively associated with the risk for breast cancer. However, only case-control studies on post-menopausal women showed a positive link. Due to limited studies and high heterogeneity, findings should be interpreted with caution. More cohort studies are needed to clarify this association.

Adiposity and breast cancer risk in postmenopausal women: Results from the UK Biobank prospective cohort

Body size is an important modifiable risk factor for postmenopausal breast cancer. However, it remains unclear whether direct measures of fat mass are better indicators of risk than anthropometric measures, or whether central adiposity may contribute to risk beyond overall adiposity. We analyzed data from 162,691 postmenopausal women in UK Biobank followed from 2006 to 2014. Body size was measured by trained technicians. Multivariable-adjusted Cox regression was used to estimate relative risks. Analyses were stratified by age at recruitment, region and socioeconomic status, and adjusted for family history of breast cancer, age at menarche, age at first birth, parity, age at menopause, previous hormone replacement therapy use, smoking, alcohol intake, height, physical activity and ethnicity. We observed 2,913 incident invasive breast cancers during a mean 5.7 years of follow-up. There was a continuous increase in risk of postmenopausal breast cancer with increasing adiposity, across all measures. The point estimate, comparing women in the top (median 37.6 kg) to bottom (median 17.6 kg) quartile of body fat mass was 1.70 (95% confidence interval 1.52-1.90). The magnitudes of the associations between per SD increase in BMI and body fat mass with breast cancer risk were similar, suggesting impedance measures of fat were not substantially better indicators of risk than anthropometric measures. After adjusting for body fat mass, the associations between anthropometric measures of central adiposity and breast cancer risk were attenuated. The magnitude of risk, across all measures of adiposity, was greater in women who had been postmenopausal for 12 or more years.

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.

Prospective cohort study of general and central obesity, weight change trajectory and risk of major cancers among Chinese women

General obesity, typically measured using body mass index (BMI), has been associated with an increased risk of several cancers. However, few prospective studies have been conducted in Asian populations. Although central obesity, often measured using waist-hip ratio (WHR), is more predictive for type 2 diabetes and cardiovascular diseases (CVD) risk than BMI, knowledge of its association with cancer incidence is limited. In a cohort of 68,253 eligible Chinese women, we prospectively investigated the association of BMI, WHR and weight change during adulthood with risk of overall cancer and major site-specific cancers using multivariate Cox proportional hazard models. Compared to the BMI group of 18.5-22.9 kg/m(2) , obese (BMI ≥ 30 kg/m(2) ) women were at an increased risk of developing overall cancer (hazard ratio = 1.36, 95% confidence interval = 1.21-1.52), postmenopausal breast cancer (HR: 2.43, 95% CI: 1.73-3.40), endometrial cancer (HR: 5.34, 95% CI: 3.48-8.18), liver cancer (HR: 1.93, 95% CI: 1.14-3.27) and epithelial ovarian cancer (HR: 2.44, 95% CI: 1.37-4.35). Weight gain during adulthood (per 5 kg gain) was associated with increased risk of all cancers combined (HR: 1.05, 95% CI: 1.03-1.08), postmenopausal breast cancer (HR: 1.17, 95% CI: 1.10-1.24) and endometrial cancer (HR: 1.37, 95% CI: 1.27-1.48). On the other hand, WHR was not associated with cancer risk after adjustment for baseline BMI. These findings suggest that obesity may be associated with cancer risk through different mechanisms from those for type 2 diabetes and CVD and support measures of maintaining health body weight to reduce cancer risk in Chinese women.

Healthy lifestyle and risk of breast cancer among postmenopausal women in the European Prospective Investigation into Cancer and Nutrition cohort study

Breast cancer is the most common cancer among women and prevention strategies are needed to reduce incidence worldwide. A healthy lifestyle index score (HLIS) was generated to investigate the joint effect of modifiable lifestyle factors on postmenopausal breast cancer risk. The study included 242,918 postmenopausal women from the multinational European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, with detailed information on diet and lifestyle assessed at baseline. The HLIS was constructed from five factors (diet, physical activity, smoking, alcohol consumption and anthropometry) by assigning scores of 0-4 to categories of each component, for which higher values indicate healthier behaviours. Hazard ratios (HR) were estimated by Cox proportional regression models. During 10.9 years of median follow-up, 7,756 incident breast cancer cases were identified. There was a 3% lower risk of breast cancer per point increase of the HLIS. Breast cancer risk was inversely associated with a high HLIS when fourth versus second (reference) categories were compared [adjusted HR = 0.74; 95% confidence interval (CI): 0.66-0.83]. The fourth versus the second category of the HLIS was associated with a lower risk for hormone receptor double positive (adjusted HR = 0.81, 95% CI: 0.67-0.98) and hormone receptor double negative breast cancer (adjusted HR = 0.60, 95% CI: 0.40-0.90). Findings suggest having a high score on an index of combined healthy behaviours reduces the risk of developing breast cancer among postmenopausal women. Programmes which engage women in long term health behaviours should be supported.

Obesity in breast cancer--what is the risk factor?

Environmental factors influence breast cancer incidence and progression. High body mass index (BMI) is associated with increased risk of post-menopausal breast cancer and with poorer outcome in those with a history of breast cancer. High BMI is generally interpreted as excess adiposity (overweight or obesity) and the World Cancer Research Fund judged that the associations between BMI and incidence of breast cancer were due to body fatness. Although BMI is the most common measure used to characterise body composition, it cannot distinguish lean mass from fat mass, or characterise body fat distribution, and so individuals with the same BMI can have different body composition. In particular, the relation between BMI and lean or fat mass may differ between people with or without disease. The question therefore arises as to what aspect or aspects of body composition are causally linked to the poorer outcome of breast cancer patients with high BMI. This question is not addressed in the literature. Most studies have used BMI, without discussion of its shortcomings as a marker of body composition, leading to potentially important misinterpretation. In this article we review the different measurements used to characterise body composition in the literature, and how they relate to breast cancer risk and prognosis. Further research is required to better characterise the relation of body composition to breast cancer.

The effect of insulin resistance on breast cancer risk in Latinas of Mexican origin

BACKGROUND

Conclusive evidence has yet to emerge regarding the association between markers of hyperinsulinemia and breast cancer. We determined the effect of insulin resistance (IR) on breast cancer risk in Latinas of Mexican origin who did not have a direct family history of breast cancer and had not been previously diagnosed with prediabetes or diabetes.

METHODS

This was a case-control study in which a case (n=124) was defined as a patient with a recent histopathologic diagnosis of breast cancer and a control (n=197) was defined as a participant who had recently undergone a mammography and had either a Breast Imaging, Reporting & Data System (BI-RADS)-1 or a BI-RADS-2 score. Plasma glucose, insulin, and glycated hemoglobin (HbA1c) levels were measured. IR was determined by using the homeostasis model assessment (HOMA-IR) criterion. Odds ratios (OR) and 95% confidence intervals (CI) were determined using unconditional binary logistic regression analysis.

RESULTS

IR was detected in 33.9% of cases and 41.6% of controls, based on a HOMA-IR ≥3.5. Although multivariate analysis did not show any association between IR and breast cancer risk (OR 0.56, 95% CI 0.31-1.01), it showed that an HbA1c ≥5.7% increased the risk of breast cancer (OR 3.41, 95% CI 1.93-6.01), regardless of menopausal status.

CONCLUSIONS

The findings suggest that IR had no effect on breast cancer risk; however HbA1c increased the risk in Latinas of Mexican origin who had not been diagnosed previously with prediabetes or diabetes and had no direct family history of breast cancer. Prospective studies are required to establish the impact of IR over time.

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.

Body mass index and breast cancer risk according to postmenopausal estrogen-progestin use and hormone receptor status

To assess the joint relationships among body mass index, menopausal status, and breast cancer according to breast cancer subtype and estrogen-progestin medication use, we conducted a meta-analysis of 89 epidemiologic reports published in English during 1980-2012 identified through a systematic search of bibliographic databases. Pooled analysis yielded a summary risk ratio of 0.78 (95% confidence interval (CI): 0.67, 0.92) for hormone receptor-positive premenopausal breast cancer associated with obesity (body mass index (weight (kg)/height (m)(2)) ≥30 compared with <25). Obesity was associated with a summary risk ratio of 1.39 (95% CI: 1.14, 1.70) for receptor-positive postmenopausal breast cancer. For receptor-negative breast cancer, the summary risk ratios of 1.06 (95% CI: 0.70, 1.60) and 0.98 (95% CI: 0.78, 1.22) associated with obesity were null for both premenopausal and postmenopausal women, respectively. Elevated postmenopausal breast cancer risk ratios associated with obesity were limited to women who never took estrogen-progestin therapy, with risk ratios of 1.42 (95% CI: 1.30, 1.55) among never users and 1.18 (95% CI: 0.98, 1.42) among users; too few studies were available to examine this relationship according to receptor subtype. Future research is needed to confirm whether obesity is unrelated to receptor-negative breast cancer in populations of postmenopausal women with low prevalence of hormone medication use.

Cohort study of risk factors for breast cancer in post menopausal women

OBJECTIVES

The present study assessed more than 800 potential risk factors to identify new predictors of breast cancer and compare the independence and relative importance of established risk factors.

METHODS

Data were collected by the Women's Health Initiative and included 147,202 women ages 50 to 79 who were enrolled from 1993 to 1998 and followed for 8 years. Analyses performed in 2011 and 2012 used the Cox proportional hazard regression to test the association between more than 800 baseline risk factors and incident breast cancer.

RESULTS

Baseline factors independently associated with subsequent breast cancer at the p<0.001 level (in decreasing order of statistical significance) were breast aspiration, family history, age, weight, history of breast biopsies, estrogen and progestin use, fewer live births, greater age at menopause, history of thyroid cancer, breast tenderness, digitalis use, alcohol intake, white race, not restless, no vaginal dryness, relative with prostate cancer, colon polyps, smoking, no breast augmentation, and no osteoporosis. Risk factors previously reported that were not independently associated with breast cancer in the present study included socioeconomic status, months of breast feeding, age at first birth, adiposity measures, adult weight gain, timing of initiation of hormone therapy, and several dietary, psychological, and exercise variables. Family history was not found to alter the risk associated with other factors.

CONCLUSIONS

These results suggest that some risk factors not commonly studied may be important for breast cancer and some frequently cited risk factors may be relatively unimportant or secondary.

Body fat and breast cancer risk in postmenopausal women: a longitudinal study

Associations between anthropometric indices of obesity and breast cancer risk may fail to capture the true relationship between excess body fat and risk. We used dual-energy-X-ray-absorptiometry- (DXA-) derived measures of body fat obtained in the Women's Health Initiative to examine the association between body fat and breast cancer risk; we compared these risk estimates with those for conventional anthropometric measurements. The study included 10,960 postmenopausal women aged 50–79 years at recruitment, with baseline DXA measurements and no history of breast cancer. During followup (median: 12.9 years), 503 incident breast cancer cases were diagnosed. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models. All baseline DXA-derived body fat measures showed strong positive associations with breast cancer risk. The multivariable-adjusted HR for the uppermost quintile level (versus lowest) ranged from 1.53 (95% CI 1.14–2.07) for fat mass of the right leg to 2.05 (1.50–2.79) for fat mass of the trunk. Anthropometric indices (categorized by quintiles) of obesity (BMI (1.97, 1.45–2.68), waist circumference (1.97, 1.46–2.65), and waist : hip ratio (1.91, 1.41–2.58)) were all strongly, positively associated with risk and did not differ from DXA-derived measures in prediction of risk.

Metabolic syndrome biomarkers and early breast cancer in Saudi women: evidence for the presence of a systemic stress response and/or a pre-existing metabolic syndrome-related neoplasia risk?

Background

Obesity has been linked to many adverse health consequences, including breast cancer. This study aims to determine adipocytokine and other biological changes in recently diagnosed breast cancer patients before therapy is started.

Methods

A total of 109 female Saudi subjects [56 newly diagnosed, treatment-naïve, histologically-confirmed breast cancer cases and 53 age- and BMI-matched controls] were enrolled in this study. Anthropometric data were collected. Serum insulin, adipocytokines and plasminogen activator inhibitor-1 (PAI-1) concentrations were measured using a customized multiplex Luminex assay. Hypersensitive C-Reactive Protein (CRP), tumor necrosis factor-alpha (TNF-α), and angiotensin II (ANG II) were measured using ELISA.

Results

A few days in the diagnosis, breast cancer subjects had significantly higher systolic blood pressure (p = 0.03), glucose (p = 0.01), triglycerides (p = 0.001), leptin (p = 0.044), resistin (p = 0.04), ANG II (p = 0.02), TNF-α (p = 0.045), and CRP (p = 0.04) than the controls. On the other hand, HDL (p = 0.01) and adiponectin (p = 0.02) were significantly lower in cancer subjects than controls. A significant association was found between elevated triglycerides (TG) and breast cancer [OR (95% CI), 6.1(1.8, 15.6), p = 0.004], as well as elevated ANG II [OR (95% CI), 5.2(1.2, 14.3), p = 0.03]. On the other hand, aPAI and HDL correlated negatively with breast cancer [OR (95% CI), 0.076(0.01, 0.34), p = 0.001; 0.30(0.09, 0.95), p 0.04, respectively].

Conclusion

Circulating ANGII and triglycerides were positively associated with early breast cancer. In contrast, HDL-cholesterol correlated negatively with ANG II and aPAI in these patients. This suggests that patients with recently diagnosed breast cancer have biochemical changes consistent with an activated stress response and/or that patients with metabolic syndrome manifestations have a higher risk of developing this disease.

Correlation of the risk of breast cancer and disruption of the circadian rhythm (Review)

Breast cancer is the worldwide leading cause of cancer incidence among women. Night shift work exposure has been recently considered one of the significant breast cancer risk factors in industrialized countries. The mechanisms by which this work exposure may be responsible for cancer development is still discussed. In the last 15 years, many authors have paid attention to the relationship between night shift work and breast cancer risk. In the current study, eight case-control studies and four prospective epidemiological studies describing such relationship are discussed. A positive correlation between night shift work and breast cancer risk was described in 8 out of 12 studies. However, different reasons suggest that some of these studies have an Achilles heel according to the International Agency of Cancer (IARC) indications. Both the circadian system alteration and the melatonin output reduction, related to the exposure to light-at-night during night shift work, remain the most valid hypotheses on the causal relation of shift work and breast cancer. Overall, the results of the present study suggest that there is an association between night shift work and breast cancer development in western countries. However, further studies are needed to confirm such association and to understand which biomolecular mechanisms may be involved in the pathogenesis of cancer diagnosed in patients with night shift work exposure.

Body size and breast cancer risk: the Multiethnic Cohort

The influence of body size on postmenopausal breast cancer risk was investigated among five racial/ethnic groups in the Multiethnic Cohort. Participants were 45-75 years old at recruitment (1993-1996), living in Hawaii and California. Of the 82,971 White, African American, Native Hawaiian, Japanese and Latina women included in this analysis, 3,030 were diagnosed with invasive breast cancer. Body mass index (BMI), height, weight and adulthood weight gain were associated with a significantly higher risk and, with the exception of height, were found to vary across ethnic groups. Native Hawaiians and Japanese with a BMI≥30.0 compared to 20.0-24.9 kg/m2 had the highest risk (hazard ratio=1.82, 95% confidence interval: 1.31, 2.54, p-trend=0.001, and hazard ratio=1.59, 95% confidence interval: 1.24, 2.05, p-trend<0.0001, respectively). Current hormone replacement therapy use modified the impact of a high BMI, as non- and former users had a significantly higher risk compared to current users. BMI also had a more pronounced risk for advanced tumors compared to localized tumors. When both BMI and adult weight gain were analyzed simultaneously, adult weight gain, rather than BMI, was a significant risk factor overall. These findings emphasize the significance of maintaining a healthy weight throughout adulthood for the prevention of postmenopausal breast cancer.

Selected elements of socio-demographic status and lifestyle as factors determining subjective assessment of life in women after mastectomy

Aim of the study

The main objective of the study is to specify whether socio-demographic factors and physical activity result in differences in subjective assessment of life in women diagnosed with breast cancer.

Material and methods

The study group consisted of 145 women who had been diagnosed with breast cancer. The women had undergone radical surgery, chemotherapy and radiotherapy. The participants filled in an anonymous questionnaire which contained a number of detailed questions relating to their socio-demographic standing, life style, condition and the current self-assessment of life after breast cancer. In order to assess the differences between groups made on the basis of socio-economic variables, the Kruskal-Wallis rank test was used. For a comprehensive assessment of relations, multiple correspondence analysis on the basis of Burt tables was used.

Results

Their mean age at the time of the study was 57.1 years. The analysis of the effect of education and marital status on differences in the assessment of quality of life showed that these variables resulted in differences in the sphere related to social contacts (better educated women more often avoided social contacts) and in feeling of fatigue and exhaustion (the participants who were in a relationship indicated less fatigue and exhaustion).

Conclusions

Mastectomy caused by breast cancer in women and related chemotherapy and radiotherapy negatively affect the physical and emotional condition of patients involving mental stress. Selected socio-demographic factors and elements of life style co-exist with each other, interpenetrating; thus the assessment of quality of life should comprise a set of factors and take into consideration their mutual interrelations.

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.

Metabolic syndrome is an independent risk factor for breast cancer

OBJECTIVE

This study was aimed to assess the prevalence of metabolic syndrome in patients with breast cancer and the independent effect of metabolic syndrome on breast cancer risk.

METHODS

Eighty-one women aged 40-80 years with breast cancer and 81 controls of similar age were screened for metabolic syndrome prevalence and breast cancer risk factors, including age at diagnosis, age at menarche, reproductive status, live births, breastfeeding, family history of breast cancer, physical activity, cigarette smoking, body mass index, and metabolic syndrome parameters. Each variable was first assessed for baseline comparisons using the univariate model, and significant variables were then added to the multivariate conditional logistic regression model.

RESULTS

Prevalence of metabolic syndrome was 59.2% in breast cancer patients, and 37% in the control group (p < 0.005). A positive and independent association was observed between metabolic syndrome and breast cancer risk (odds ratio = 2.49; 95% confidence interval 1.17-5.30).

CONCLUSION

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

Screening and prevention of breast cancer in primary care

Mammography remains the mainstay of breast cancer screening. There is little controversy that mammography reduces the risk of dying from breast cancer by about 23% among women between the ages of 50 and 69 years, although the harms associated with false-positive results and overdiagnosis limit the net benefit of mammography. Women in their 70s may have a small benefit from screening mammography, but overdiagnosis increases in this age group as do competing causes of death. While new data support a 16% reduction in breast cancer mortality for 40- to 49-year-old women after 10 years of screening, the net benefit is less compelling in part because of the lower incidence of breast cancer in this age group and because mammography is less sensitive and specific in women younger than 50 years. Digital mammography is more sensitive than film mammography in young women with similar specificity, but no improvements in breast cancer outcomes have been demonstrated. Magnetic resonance imaging may benefit the highest risk women. Randomized trials suggest that self-breast examination does more harm than good. Primary prevention with currently approved medications will have a negligible effect on breast cancer incidence. Public health efforts aimed at increasing mammography screening rates, promoting regular exercise in all women, maintaining a healthy weight, limiting alcohol intake, and limiting postmenopausal hormone therapy may help to continue the recent trend of lower breast cancer incidence and mortality among American women.

A longitudinal study of the metabolic syndrome and risk of postmenopausal breast cancer

The metabolic syndrome, characterized by abdominal obesity, high blood glucose levels, impaired glucose tolerance, dyslipidemia, and hypertension, is associated with increased risk of type 2 diabetes and coronary heart disease. Several studies have examined the association of the individual components of the metabolic syndrome with breast cancer; to date, however, no study has assessed the metabolic syndrome per se in relation to breast cancer risk. Furthermore, previous studies have relied only on baseline assessment of components of the syndrome. Therefore, we assessed the association of the metabolic syndrome with the risk of postmenopausal breast cancer among women in the 6% sample of subjects in the Women's Health Initiative clinical trial and the 1% sample of women in the observational study who had repeated measurements of the components of the syndrome during follow-up. We used Cox proportional hazards models to estimate hazard ratios and 95% confidence intervals for the association of breast cancer risk with the presence of the metabolic syndrome, as well as its components, at baseline and in time-dependent analyses. After exclusion of women with diabetes, among 4,888 women with baseline measurements, 165 incident cases of breast cancer were ascertained over a median of 8 years of follow-up. The presence of the metabolic syndrome at baseline was not associated with altered risk. Of the individual components measured at baseline, diastolic blood pressure showed a borderline positive association with breast cancer. In time-dependent covariate analyses, however, certain scenarios indicated a positive association between the metabolic syndrome and breast cancer, due primarily to positive associations with serum glucose, serum triglycerides, and diastolic blood pressure.

Combined effects of obesity and type 2 diabetes contribute to increased breast cancer risk in premenopausal women

Background

Both obesity and type 2 diabetes are among the risk factors for breast cancer development. Combined effect of these metabolic abnormalities on breast cancer risk however, has not been examined in premenopausal women. We tested this association in type 2 diabetic women, categorized as obese, overweight and normal body weight groups based on BMI.

Design and methods

A total of 101 subjects were included in this study. Serum levels of IL-6, TNF-α, C reactive protein, leptin, TGF-α, adiponectin and insulin were measured by ELISA. Data were logarithmically transformed for variables not normally distributed. Analysis of variance with post-hoc Bonferroni was applied to compare the data between the groups. Simple and partial correlation coefficients between the variables were determined and a stepwise multiple linear regression analysis was performed to determine the relationships between the variables of interest.

Results

Significantly increased levels of IL-6, C reactive protein, leptin and significantly decreased levels of adiponectin were found in obese group, while the levels of TNF-α and TGF-α were unaltered. A positive correlation between waist circumference and IL-6 was found in obese group. Similarly, C reactive protein, waist and hip circumferences were linearly correlated with BMI in obese group. Stepwise multiple linear regression analysis revealed several significant predictors for breast cancer risk.

Conclusion

Obesity and type 2 diabetes, owing to their effects on adipocytokines and inflammatory mediators, contribute to increased breast cancer risk in premenopausal women. This study emphasizes healthy life style and better management of these metabolic disorders to avoid the pathogenesis of breast cancer and of other chronic diseases.

Do chronological age and selected socio-demographic factors affect quality of life in females with breast cancer?

The main aim of this study is to determine whether chronological age and selected socio-demographic factors affect quality of life in females with breast cancer. The sample group consisted of 145 females between 32.0 and 84.4 years of age, after radical surgery treatment, chemotherapy, radiotherapy and undergoing hormonotherapy. The results indicate no significant differences between individuals varied by chronological age, and by place of residence. The time elapsed since the diagnosis was a significant differentiating factor in terms of the self-reported extent of positive emotions, cognitive problems and sexual functioning. Higher educated females were more inclined to social avoidance and more severely affected by fatigue - those with partners more so than single ones. The distress related to the disease and its treatment degrades the patients' quality of life so severely that other factors, such as socio-demographic, chronological age or period since diagnosis, do not play as an important role in a subjective evaluation of quality of life. One needs to be cognizant of the variety of coexisting factors, including psychological and characterological, that contribute to the quality of life evaluation.

Body mass index, waist to hip ratio and waist/height in adult Polish women in relation to their education, place of residence, smoking and alcohol consumption

Obesity is a complex, multifactorial disorder that develops from genotype and environmental interactions. The aim of this study is to describe the variability of body mass index (BMI), waist to hip ratio (WHR) and waist to height (W/Ht) in adult Polish women, and to determine relationships between these variables and factors such as education, place of residence, smoking and alcohol drinking. The tested group consisted of 10,254 women aged 25-95 years, who voluntarily filled in questionnaires and participated in anthropometric measurements (body height and mass, waist and hip circumferences). The BMI, WHR and W/Ht values were calculated based on these measurements. The participants were differentiated in terms of education, residence and lifestyle (smoking, alcohol drinking). Chi-squared test, product-moment correlations, ANOVA, multiple correspondence analysis (MCA) and logistic regression with backward elimination were used to evaluate associations between social and lifestyle factors and BMI, WHR and W/Ht. The results confirm (1) the relationship between low social status and the risk of overweight and obesity as observed in developed countries; (2) higher susceptibility to environmental factors such as education, place of residence, smoking and alcohol drinking in younger (premenopausal) women; (3) the usefulness of simple and practical anthropometric indicators such as WHR and W/Ht for the identification of the higher risk of future metabolic diseases in obese people and those with a normal body mass.

Somatotype and risk of breast cancer: a case-control study in Uruguay

According to the evidence, there is a need for more thorough assessment and quantification of body size and shape and the risk of breast cancer. Using the somatotype methodology, we carried out an original research in order to explore possible associations between body shape and the risk of breast cancer in Uruguayan women. With this objective, 254 recent breast cancer cases and 1,000 frequency-matched healthy controls were interviewed on menstrual and reproductive story, and a series of skinfolds, circumferences and diameters were measured specifically to calculate somatotype. A positive association with breast cancer was found for high endomorphy (Odds Ratio [OR] = 2.82, p < 0.001), mainly among pre-menopausal women (OR = 4.98, p <0.001) and normoweight women (OR = 5.12, p = 0.002), whereas almost no differences were observed for mesomorphic and ectomorphic women. Analysis showed a high meso-endomorphic pattern in the study population. Further studies are needed to confirm the present results obtained in a country with high incidence of the disease.

Insulin resistance, obesity and breast cancer risk

Breast cancer (BC) is one of the most important problems of public health. Among the avoidable risk factors during a woman's life, overweight and obesity are very important ones. Furthermore they are increasing worldwide. The risk of breast cancer is traditionally linked to obesity in postmenopausal women; conversely, it is neutral or even protective in premenopausal women. Since the initiator and promoter factors for BC act over a long time, it seems unlikely that the menopausal transition may have too big an impact on the role of obesity in the magnitude of the risk. We reviewed the literature in an attempt to understand this paradox, with particular attention to the body fat distribution and its impact on insulin resistance. The association of insulin resistance and obesity with BC risk are biologically plausible and consistent. Estradiol (E2) and IGFs act as mitogens in breast cancer cells. They act together and reciprocally. However the clinical and biological methods to assess the impact of insulin resistance are not always accurate. Furthermore insulin resistance is far from being a constant feature in obesity, particularly in premenopausal women; this complicates the analysis and explains the discrepancies in large prospective trials. The most consistent clinical feature to assess risk across epidemiological studies seems to be weight gain during lifetime. Loss of weight is associated with a lower risk for postmenopausal BC compared with weight maintenance. This observation should be an encouragement for women since loss of weight may be an effective strategy for breast cancer risk reduction.

Diabetes, metabolic syndrome, and breast cancer: a review of the current evidence

Incidences of breast cancer, type 2 diabetes, and metabolic syndrome have increased over the past decades with the obesity epidemic, especially in industrialized countries. Insulin resistance, hyperinsulinemia, and changes in the signaling of growth hormones and steroid hormones associated with diabetes may affect the risk of breast cancer. We reviewed epidemiologic studies of the association between type 2 diabetes and risk of breast cancer and the available evidence on the role of hormonal mediators of an association between diabetes and breast cancer. The combined evidence supports a modest association between type 2 diabetes and the risk of breast cancer, which appears to be more consistent among postmenopausal than among premenopausal women. Despite many proposed potential pathways, the mechanisms underlying an association between diabetes and breast cancer risk remain unclear, particularly because the 2 diseases share several risk factors, including obesity, a sedentary lifestyle, and possibly intake of saturated fat and refined carbohydrates, that may confound this association. Although the metabolic syndrome is closely related to diabetes and embraces additional components that might influence breast cancer risk, the role of the metabolic syndrome in breast carcinogenesis has not been studied and thus remains unknown.