Body size and breast cancer risk in black women and white women: the Carolina Breast Cancer Study

What Is Known about Breast Cancer in Young Women?

Breast cancer (BC) is the second leading cause of cancer-related death in women under the age of 40 years worldwide. In addition, the incidence of breast cancer in young women (BCYW) has been rising. Young women are not the focus of screening programs and BC in younger women tends to be diagnosed in more advanced stages. Such patients have worse clinical outcomes and treatment complications compared to older patients. BCYW has been associated with distinct tumour biology that confers a worse prognosis, including poor tumour differentiation, increased Ki-67 expression, and more hormone-receptor negative tumours compared to women >50 years of age. Pathogenic variants in cancer predisposition genes such as BRCA1/2 are more common in early-onset BC compared to late-onset BC. Despite all these differences, BCYW remains poorly understood with a gap in research regarding the risk factors, diagnosis, prognosis, and treatment. Age-specific clinical characteristics or outcomes data for young women are lacking, and most of the standard treatments used in this subpopulation currently are derived from older patients. More age-specific clinical data and treatment options are required. In this review, we discuss the epidemiology, clinicopathologic characteristics, outcomes, treatments, and special considerations of breast cancer in young women. We also underline future directions and highlight areas that require more attention in future studies.

Association of Obesity and Diabetes With the Incidence of Breast Cancer in Louisiana

INTRODUCTION

Breast cancer is a heterogeneous disease, consisting of multiple molecular subtypes. Obesity has been associated with an increased risk for postmenopausal breast cancer, but few studies have examined breast cancer subtypes separately. Obesity is often complicated by type 2 diabetes, but the possible association of diabetes with specific breast cancer subtypes remains poorly understood.

METHODS

In this retrospective case-control study, Louisiana Tumor Registry records of primary invasive breast cancer diagnosed in 2010-2015 were linked to electronic health records in the Louisiana Public Health Institute's Research Action for Health Network. Controls were selected from Research Action for Health Network and matched to cases by age and race. Conditional logistic regression was used to identify metabolic risk factors. Data analysis was conducted in 2020‒2021.

RESULTS

There was a significant association between diabetes and breast cancer for Luminal A, Triple-Negative Breast Cancer, and human epidermal growth factor 2‒positive subtypes. In multiple logistic regression, including both obesity status and diabetes as independent risk factors, Luminal A breast cancer was also associated with overweight status. Diabetes was associated with increased risk for Luminal A and Triple-Negative Breast Cancer in subgroup analyses, including women aged ≥50 years, Black women, and White women.

CONCLUSIONS

Although research has identified obesity and diabetes as risk factors for breast cancer, these results underscore that comorbid risk is complex and may differ by molecular subtype. There was a significant association between diabetes and the incidence of Luminal A, Triple-Negative Breast Cancer, and human epidermal growth factor 2‒positive breast cancer in Louisiana.

Metabolic Syndrome and Breast Cancer Molecular Subtypes: An Observational Patient Study

Background:

Breast cancer molecular subtypes share various prognostic profiles, and luminal A molecular subtypes have a better prognosis compared with other molecular subtypes. However, whether metabolic syndrome or individual risk factors of metabolic syndrome influence on the development of molecular subtype remains elusive. We aimed to assess the association between metabolic syndrome risk factors and breast cancer molecular subtypes among patients with metabolic syndrome in a clinical setting.

Methods:

In total, 101 breast cancer patients with mean age, 58.4 ± 8.5 years, and overt metabolic syndrome prospectively were recruited. Immunohistochemistry procedure was used to determine molecular subtypes. Assessment of clinical, biochemical, and anthropometric parameters was performed. Logistic regression analysis was used to assess the relationship between risk factors and breast cancer molecular subtypes categories. A similar approach was used to assess the relation between breast cancer molecular subtypes and menopause.

Results:

Comparison of metabolic syndrome individual risk factors according to breast cancer molecular subtypes no statistical difference was found for systolic (P = .33) and diastolic blood pressure (P = .17), fasting glucose (P = .77), triglycerides (P = .62), high-density lipoprotein (P = .33), body mass index (P = .87), and waist circumference (P = .81). A positive trend was found between high-density lipoprotein and HER2+. No association was found with other risk factors. Moreover, an association was found between HER2+ categories and menopause.

Conclusion:

In breast cancer patients with metabolic syndrome, we observed an increased trend between high-density lipoprotein and HER2+ molecular subtype, suggesting that underlying dyslipidemia may favor poor prognosis. HER2+ was associated with menopause which may influence further expression of HER2+ .

Obesity in early onset breast cancer in African American patients

Obesity is a modifiable risk factor in breast cancer patients and is predictive of disease outcomes in early-onset breast cancer survivors. The purpose of this review is to summarize the current evidence in the association between early-onset breast cancer and obesity, specifically in African-American women. Reviewing the molecular mechanisms and social determinants of disease in this population can provide a foundation for future interventions in prevention, detection, and treatment aiming at improving outcomes for young breast cancer patients.

A Review of Modifiable Risk Factors in Young Women for the Prevention of Breast Cancer

Breast cancer is the most common cancer diagnosis in women aged less than 40 years and the second most common cause of cancer death in this age group. Global rates of young onset breast cancer have risen steadily over the last twenty years. Although young women with breast cancer have a higher frequency of underlying pathogenic mutations in high penetrance breast cancer susceptibility genes (CSG) than older women, the vast majority of young breast cancer patients are not found to have a germline CSG mutation. There is therefore a need to inform young women regarding non-genetic breast cancer risk factors which have the potential to be influenced by changes in individual behaviour. A Pubmed search was performed using the search terms “young” or “early onset”, and “breast cancer” and “modifiable risk”. Titles and abstracts from peer-reviewed publications were screened for relevance. This review presents evidence for potentially modifiable risk factors of breast cancer risk in young women, including lifestyle factors (physical activity, body habitus, alcohol use, smoking, shift work and socioeconomic factors), reproductive and hormonal factors and iatrogenic risks. The extent to which these factors are truly modifiable is discussed and interactions between genetic and non-genetic risk factors are also addressed. Health care professionals have an opportunity to inform young women about breast health and risk when presenting at a “teachable moment”, including the benefits of physical activity and alcohol habits as risk factor. More focussed discussions regarding individual personal risk and benefit should accompany conversations regarding reproductive health and take into consideration both non-modifiable and iatrogenic BC risk factors.

Fish/shellfish intake and the risk of head and neck cancer

Fish intake and other dietary sources of omega-3 fatty acids have been shown to be associated with a reduced risk for some cancers. Although previous studies of head and neck cancer have reported associations with different dietary factors, including reduced risks for fruits and vegetables and putatively healthy dietary patterns, associations specific to fish intake are unclear. This study investigated the association between fish/shellfish intake and risk of squamous cell carcinoma of the head and neck (SCCHN) using data from the Carolina Head and Neck Cancer Epidemiology Study, a population-based case-control study conducted in 46 North Carolina counties with cases recruited from 2002 through 2006. Controls were frequency matched to the cases on age, sex, and race; the final sample size was 1039 cases and 1375 controls. Demographic, lifestyle, and dietary information were collected using an in-person interviewer-administered structured questionnaire. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated with unconditional logistic regression. Patients whose fish/shellfish intake was among the highest tertile had a 20% lower odds of SCCHN compared with those in the lowest tertile (OR: 0.80; 95% CI: 0.60-1.07) after adjustment for the matching and other factors (income, energy intake, fruit intake, cigarette smoking, and alcohol intake). The inverse association was more pronounced for oral cavity and oropharyngeal tumors, for African Americans, and for females, but CIs were wide. To further investigate this potential risk reduction strategy for SCCHN, future studies should consider examining specific fish/shellfish, cooking practices, and other omega-3 fatty acid sources.

Metformin Targets Glucose Metabolism in Triple Negative Breast Cancer

Metformin is the most widely administered anti-diabetic agent worldwide. In patients receiving metformin for metabolic syndrome or diabetes, it reduces the incidence and improves the survival of breast cancer (BC) patients. We have previously shown that metformin is particularly potent against triple negative breast cancer (TNBC), with a reduction of proliferation, oncogenicity and motility, inhibition of pro-oncogenic signaling pathways and induction of apoptosis. These BCs are well recognized to be highly dependent on glucose/glucosamine (metabolized through anaerobic glycolysis) and lipids, which are metabolized for the production of energy and cellular building blocks to sustain a high rate of proliferation. We have previously demonstrated that metformin inhibits lipid metabolism, specifically targeting fatty acid synthase (FASN), cholesterol biosynthesis and GM1 lipid rafts in TNBC. We also reported that glucose promotes phenotypic aggression and reduces metformin efficacy. We now show that metformin inhibits several key enzymes requisite to glucose metabolism in TNBC, providing additional insight into why metformin is especially toxic to this subtype of BC. Our data suggests that the use of metformin to target key metabolic defects in lipid and carbohydrate metabolism in cancer may be broadly applicable, especially against highly aggressive malignant cells.

Obesity and survival in the neoadjuvant breast cancer setting: role of tumor subtype in an ethnically diverse population

BACKGROUND

Obesity may negatively affect survival in breast cancer (BC), but studies are conflicting, and associations may vary by tumor subtypes and race/ethnicity groups.

METHODS

In a retrospective review, we identified 273 women with invasive BC administered Adriamycin/Taxane-based neoadjuvant chemotherapy from 2004 to 2016 with body mass index (BMI) data at diagnosis. Obesity was defined as BMI ≥30. Associations between obesity and event-free survival (EFS), using STEEP events, and overall survival (OS), using all-cause mortality, were assessed overall and stratified by tumor subtype [[Hormone Receptor Positive (HR+)/HER2-, HER2+, and Triple-Negative Breast Cancer (TNBC])] in our diverse population.

RESULTS

Median follow-up was 32.6 months (range 5.7-137.8 months). Overall, obesity was associated with worse EFS (HR 1.71, 95% CI 1.03-2.84, p = 0.04) and a trend towards worse OS (p = 0.13). In HR+/HER2- disease (n = 135), there was an interaction between obesity and hormonal therapy with respect to OS but not EFS. In those receiving tamoxifen (n = 33), obesity was associated with worse OS (HR 9.27, 95% CI 0.96-89.3, p = 0.05). In those receiving an aromatase inhibitor (n = 89), there was no association between obesity and OS. In TNBC (n = 44), obesity was associated with worse EFS (HR 2.62, 95% CI 1.03-6.66, p = 0.04) and a trend towards worse OS (p = 0.06). In HER2+ disease (n = 94), obesity was associated with a trend towards worse EFS (HR 3.37, 95% CI 0.97-11.72, p = 0.06) but not OS. Race/ethnicity was not associated with survival in any subtype, and there were no interactions with obesity on survival.

CONCLUSIONS

Obesity may negatively impact survival, with differences among tumor subtypes.

Racial and ethnic disparities in the impact of obesity on breast cancer risk and survival: a global perspective

Obesity is a global concern, affecting both developed and developing countries. Although there are large variations in obesity and breast cancer rates worldwide and across racial/ethnic groups, most studies evaluating the impact of obesity on breast cancer risk and survival have been conducted in non-Hispanic white women in the United States or Europe. Given the known racial/ethnic differences in tumor hormone receptor subtype distribution, obesity prevalence, and risk factor profiles, we reviewed published data for women of African, Hispanic, and Asian ancestry in the United States and their countries of origin. Although the data are limited, current evidence suggests a stronger adverse effect of obesity on breast cancer risk and survival in women of Asian ancestry. For African Americans and Hispanics, the strength of the associations appears to be more comparable to that of non-Hispanic whites, particularly when accounting for subtype and menopausal status. Central obesity seems to have a stronger impact in African-American women than general adiposity as measured by body mass index. International data from countries undergoing economic transition offer a unique opportunity to evaluate the impact of rapid weight gain on breast cancer. Such studies should take into account genetic ancestry, which may help elucidate differences in associations between ethnically admixed populations. Overall, additional large studies that use a variety of adiposity measures are needed, because the current evidence is based on few studies, most with limited statistical power. Future investigations of obesity biomarkers will be useful to understand possible racial/ethnic biological differences underlying the complex association between obesity and breast cancer development and progression.

African Americans and Hispanics Remain at Lower Risk of Ovarian Cancer Than Non-Hispanic Whites after Considering Nongenetic Risk Factors and Oophorectomy Rates

BACKGROUND

Risk factors for invasive epithelial ovarian cancer (IEOC) among Hispanics and African Americans are understudied despite notable differences in incidence relative to non-Hispanic whites.

METHODS

We used multivariate logistic regression to examine parity, oral contraceptive use, tubal ligation, endometriosis, family history of ovarian cancer, and talc use and risk of IEOC among Hispanics (308 cases and 380 controls), African Americans (128 cases and 143 controls), and non-Hispanic whites (1,265 cases and 1,868 controls) using four case-control studies we conducted in Los Angeles County. We expressed each of these factors in the form of increasing risk and calculated population attributable risk percentage (PAR%) estimates for the six risk factors separately and jointly in the three groups.

RESULTS

The risk associations with these six well-accepted factors were comparable in the three groups. The significant racial/ethnic differences in the prevalence of these factors and differences in their oophorectomy rates explained 31% of the lower incidence in African Americans compared with non-Hispanic whites, but only 13% of the lower incidence in Hispanics. The PAR%s ranged from 27.5% to 31.0% for no tubal ligation, 15.9% to 22.2% for not using oral contraceptives, and 12.2% to 15.1% for using talc in the three groups.

CONCLUSIONS

All six risk factors are comparably important in the three groups. Differences in the prevalence of these factors and their oophorectomy rates explained approximately one third of the difference in incidence between African Americans and non-Hispanic whites.

IMPACT

Devising strategies to lessen the burden of IEOC will be applicable to all three racial/ethnic groups.

Energy-Related Indicators and Breast Cancer Risk among White and Black Women

Energy-related indicators, including physical activity, energy intake, body mass index (BMI) and adult weight change, have been linked to breast cancer risk. Very few studies of these associations have been conducted among black women, therefore we used the Nashville Breast Health Study (NBHS) to determine whether similar effects were seen in black and white women. The NBHS is a population-based case-control study of breast cancer among women age 25 to 75 years conducted between 2001 and 2010 in and around the Nashville Metropolitan area. Telephone interviews and self-administered food frequency questionnaires were completed with 2,614 incident breast cancer cases ascertained through hospitals and the statewide cancer registry, and 2,306 controls selected using random digit dialing. Among premenopausal white and black women, there was little effect of adult exercise or other energy-related indicators on breast cancer risk, regardless of tumor estrogen receptor (ER) status. The beneficial effect of adult exercise on postmenopausal breast cancer appeared to be comparable between white and black women (highest tertile relative to none - white odds ratio [OR] 0.8, 95% confidence interval [CI] 0.6-1.0, p for trend=0.05; black OR 0.7, 95% CI 0.4-1.1, p for trend=0.07); however, among black women the reduction was limited to those with ER-positive disease. White and black women should be encouraged to engage in more physical activity to reduce their risk of postmenopausal breast cancer.

Obesity, body fat distribution, and risk of breast cancer subtypes in African American women participating in the AMBER Consortium

African American (AA) women are more likely than white women to be obese and to be diagnosed with ER- and triple-negative (TN) breast cancer, but few studies have evaluated the impact of obesity and body fat distribution on breast cancer subtypes in AA women. We evaluated these associations in the AMBER Consortium by pooling data from four large studies. Cases were categorized according to hormone receptor status as ER+, ER-, and TN (ER-, PR-, and HER2-) based on pathology data. A total of 2104 ER+ cases, 1070 ER- cases (including 491 TN cases), and 12,060 controls were included. Odds ratios (OR) and 95 % confidence intervals (CI) were computed using logistic regression, taking into account breast cancer risk factors. In postmenopausal women, higher recent (most proximal value to diagnosis/index date) BMI was associated with increased risk of ER+ cancer (OR 1.31; 95 % CI 1.02-1.67 for BMI ≥ 35 vs. <25 kg/m(2)) and with decreased risk of TN tumors (OR 0.60; 95 % CI 0.39-0.93 for BMI ≥ 35 vs. <25). High young adult BMI was associated with decreased premenopausal ER+ cancer and all subtypes of postmenopausal cancer, and high recent waist-to-hip ratio with increased risk of premenopausal ER+ tumors (OR 1.35; 95 % CI 1.01-1.80) and all tumor subtypes combined in postmenopausal women (OR 1.26; 95 % CI 1.02-1.56). The impact of general and central obesity varies by menopausal status and hormone receptor subtype in AA women. Our findings imply different mechanisms for associations of adiposity with TN and ER+ breast cancers.

A case-control analysis of oral contraceptive use and breast cancer subtypes in the African American Breast Cancer Epidemiology and Risk Consortium

Introduction

Recent oral contraceptive (OC) use has been consistently associated with increased risk of breast cancer, but evidence on specific breast cancer subtypes is sparse.

Methods

We investigated recency and duration of OC use in relation to molecular subtypes of breast cancer in a pooled analysis of data from the African American Breast Cancer Epidemiology and Risk Consortium. The study included 1,848 women with estrogen receptor-positive (ER+) breast cancer, 1,043 with ER-negative (ER-) breast cancer (including 494 triple negative (TN) tumors, which do not have receptors for estrogen, progesterone, and human epidermal growth factor 2), and 10,044 controls. Multivariable polytomous logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for exposure categories relative to never use, controlling for potential confounding variables.

Results

OC use within the previous 5 years was associated with increased risk of ER+ (OR 1.46, 95% CI 1.18 to 1.81), ER- (OR 1.57, 95% CI 1.22 to 1.43), and TN (OR 1.78, 95% CI 1.25 to 2.53) breast cancer. The risk declined after cessation of use but was apparent for ER+ cancer for 15 to 19 years after cessation and for ER- breast cancer for an even longer interval after cessation. Long duration of use was also associated with increased risk of each subtype, particularly ER-.

Conclusions

Our results suggest that OC use, particularly recent use of long duration, is associated with an increased risk of ER+, ER-, and TN breast cancer in African American women. Research into mechanisms that explain these findings, especially the association with ER- breast cancer, is needed.

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 size across the life course and risk of premenopausal and postmenopausal breast cancer in Black women, the Carolina Breast Cancer Study, 1993-2001

BACKGROUND

It is believed that greater adiposity is associated with reduced risk of breast cancer in premenopausal but increased risk in postmenopausal women. However, few studies have evaluated these relationships among Black women or examined anthropometric measures other than near-diagnosis body mass index (BMI).

PURPOSE

This study investigated associations between measures of body size across the life course and breast cancer risk among Black and White women living in the US South.

METHODS

We used data from the Carolina Breast Cancer Study, a population-based case-control study of invasive breast cancer in North Carolina women aged 20-74 years. We assessed nine body size variables, including age 10 relative weight; age 18 BMI; adult weight gain; "reference" BMI 1 year before interview; and post-diagnosis measured BMI and abdominal obesity measures.

RESULTS

Among premenopausal Whites, heavier childhood relative weight was associated with decreased cancer risk [odds ratio (OR) 0.48 95 % confidence interval 0.33-0.70]. Among premenopausal Blacks, greater adult waist circumference and waist-to-hip ratio (WHR) were associated with increased risk [waist OR 1.40 (1.00-1.97) and high tertile WHR OR 2.03 (1.29-3.19)], with associations for WHR in a similar direction in Whites. Among postmenopausal women, recalled body size was not associated with risk, except for increased risk associated with adult weight gain among White non-hormone therapy users. ER/PR status and hormone therapy use also modified other associations.

DISCUSSION

In this population, greater adult BMI was not associated with increased breast cancer risk, but some measures of early-life body size and abdominal obesity were associated with risk.

Anthropometry, silhouette trajectory, and risk of breast cancer in Mexican women

BACKGROUND

Obesity has been associated with breast cancer risk in the Caucasian population but the association remains unclear in the Hispanics. Previous studies conducted among Hispanics in the U.S. have shown inconsistent results.

PURPOSE

The association between anthropometry, body shape evolution across lifetime, and the risk of breast cancer was assessed using a multi-center population-based case-control study conducted in Mexico.

METHODS

One thousand incident cases and 1074 matched control women aged 35-69 years were recruited between 2004 and 2007, and analyzed in 2011-2012. Conditional logistic regression models were used.

RESULTS

Height was related to an increased risk of breast cancer in both premenopausal (p trend=0.03) and postmenopausal women (p trend=0.002). In premenopausal women, increase in BMI; waist circumference (WC); hip circumference (HC); and waist-hip ratio (WHR) were inversely associated with breast cancer risk (p trends<0.001 for BMI and WC, 0.003 for HC, and 0.016 for WHR). In postmenopausal women, decreased risks were observed for increased WC (p trend=0.004) and HC (p trend=0.009) among women with time since menopause <10 years. Further analysis of body shape evolution throughout life showed strong and significant increase in risk of breast cancer among women with increasing silhouettes size over time compared to women with no or limited increase.

CONCLUSIONS

These findings suggest that anthropometric factors may have different associations with breast cancer risk in Hispanic women than in Caucasian women. This study also shows the importance of considering the evolution of body shape throughout life.

Metabolic syndrome-breast cancer link varies by intrinsic molecular subtype

BACKGROUND

Metabolic syndrome (MS) has been shown to increase the risk of breast cancer. Existing data suggest that the strength of metabolic syndrome-breast cancer link varies by intrinsic molecular subtype, but results from worldwide literature are controversial. Primary endpoint of the study was to assess whether MS is a predictor of specific breast cancer (BC) subtype. Secondary endpoint was to determine whether components of MS can individually increase the risk of specific breast cancer subtype.

METHODS

Anthropometric and metabolic variables were correlated to breast cancer specific subgroups, retrospectively. Statistical significance was considered when p ≤ 0.05 and 95% CI.

RESULTS

Data analysis suggests that MS per se represents a modifiable risk factor for BC in postmenopausal [OR 6.28 (95% CI 2.79-14.11) p < 0.00001]. MS per se prevalence is higher among Luminal breast cancers in postmenopausal [OR 1.37 (95% CI 1.07-2.80) p = 0.03]. Body Mass Index (BMI) alone is associated to Luminal A subtype breast cancer risk [OR 1.12 (95% CI 0.96-2.196 p = 0.2]. Waist Circumference > 88 cm has been shown to be specifically and statistically significant associated to HER-2+ breast cancer subtypes in postmenopausal [OR 2.72 (95% CI 1.69- 10.72) p = 0.01], whilst in Luminal B it was only marginally statistical associated [OR 2.21 (95% CI 0.77-2.60) p = 0.1]. Insulin resistance showed statistical significant association to HER-2+ and Luminal B tumors [OR 2.11 (95% CI 1.66-6.69) p = 0.05] and [OR 2.33 (95% CI 1.2-4.2) p = 0.006], respectively. Hence, it has emerged that BMI is weakly associated to Luminal A breast cancers in this case series, whereas visceral obesity and insulin resistance are likely to be linked to more aggressive breast cancer subtypes.

CONCLUSIONS

New molecular biomarkers unveiling metabolic syndrome related breast carcinogenesis need to be detected to further stratify breast cancer risk by subtypes.

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.

A collaborative study of the etiology of breast cancer subtypes in African American women: the AMBER consortium

PURPOSE

Breast cancer is a heterogeneous disease, with at least five intrinsic subtypes defined by molecular characteristics. Tumors that express the estrogen receptor (ER+) have better outcomes than ER- tumors, due in part to the success of hormonal therapies that target ER+ tumors. The incidence of ER- breast cancer, and the subset of ER- cancers that are basal-like, is about twice as high among African American (AA) women as among US women of European descent (EA). This disparity appears to explain, in part, the disproportionately high mortality from breast cancer that occurs in AA women. Epidemiologic research on breast cancer in AA women lags behind research in EA women. Here, we review differences in the etiology of breast cancer subtypes among AA women and describe a new consortium of ongoing studies of breast cancer in AA women.

METHODS

We combined samples and data from four large epidemiologic studies of breast cancer in AA women, two cohort and two case-control, creating the African American Breast Cancer Epidemiology and Risk consortium. Tumor tissue is obtained and stored in tissue microarrays, with assays of molecular markers carried out at a pathology core. Genotyping, carried out centrally, includes a whole exome SNP array and over 180,000 custom SNPs for fine-mapping of genome-wide association studies loci and candidate pathways.

RESULTS

To date, questionnaire data from 5,739 breast cancer cases and 14,273 controls have been harmonized. Genotyping of the first 3,200 cases and 3,700 controls is underway, with a total of 6,000 each expected by the end of the study period.

CONCLUSIONS

The new consortium will likely have sufficient statistical power to assess potential risk factors, both genetic and non-genetic, in relation to specific subtypes of breast cancer in AA women.

Body size, modifying factors, and postmenopausal breast cancer risk in a multiethnic population: the San Francisco Bay Area Breast Cancer Study

Data on body size and postmenopausal breast cancer in Hispanic and African American women are inconsistent, possibly due to the influence of modifying factors. We examined associations between adiposity and risk of breast cancer defined by hormone receptor status in a population-based case-control study conducted from 1995-2004 in the San Francisco Bay Area. Multivariate adjusted odds ratios and 95% confidence intervals were calculated using unconditional logistic regression. Associations with body size were limited to women not currently using menopausal hormone therapy (801 cases, 1336 controls). High young-adult body mass index (BMI) was inversely associated with postmenopausal breast cancer risk, regardless of hormone receptor status, whereas high current BMI and high adult weight gain were associated with two-fold increased risk of estrogen receptor and progesterone receptor positive breast cancer, but only in women with a low young-adult BMI (≤22.4 kg/m(2)) or those with ≥15 years since menopause. Odds ratios were stronger among non-Hispanic Whites than Hispanics and African Americans. Waist circumference and waist-to-height ratio increased breast cancer risk in Hispanics and African Americans only, independent of BMI. These findings emphasize the importance of considering tumor hormone receptor status and other modifying factors in studies of racially/ethnically diverse populations.

Body fatness and breast cancer risk in women of African ancestry

BACKGROUND

Obesity has been shown to be inversely associated with breast cancer risk in premenopausal women, while increasing risk in postmenopausal women. However, the current evidence is largely based on studies in Caucasian populations. Associations in women of African ancestry (AA), who have a higher prevalence of obesity, have been evaluated in few studies and results suggest different effects.

METHODS

We evaluated the impact of body size, body fat distribution, and body composition on breast cancer risk among AA women (978 cases and 958 controls) participating in the Women's Circle of Health Study, a multi-site case-control study in New York City (NYC) and New Jersey (NJ). Cases were newly diagnosed with histologically confirmed ductal carcinoma in situ or invasive breast cancer, age 20-75 yrs. In NYC, cases were recruited through hospitals with the largest referral patterns for AA women and controls through random digit dialing (RDD). In NJ, cases were identified in seven counties in NJ thorough the NJ State Cancer Registry, and controls through RDD and community-based recruitment. During in-person interviews, questionnaires were administered and detailed anthropometric measurements were obtained. Body composition was assessed by bioelectrical impedance analysis.

RESULTS

BMI did not have a major impact on pre- or post-menopausal breast cancer, but was significantly associated with reduced risk of ER-/PR- tumors among postmenopausal women (OR: 0.37; 95% CI: 0.15-0.96 for BMI > 30 vs. BMI < 25). Furthermore, increased premenopausal breast cancer risk was found for higher waist and hip circumferences after adjusting for BMI, with ORs of 2.25 (95% CI: 1.07-4.74) and 2.91 (95% CI: 1.39-6.10), respectively, comparing the highest vs. lowest quartile. While ORs for higher fat mass and percent body fat among postmenopausal women were above one, confidence intervals included the null value.

CONCLUSIONS

Our study suggests that in AA women BMI is generally unrelated to breast cancer. However, higher waist and hip circumferences were associated with increased pre-menopausal breast cancer risk, while general obesity was associated with decreased risk of ER-/PR- tumors. Larger studies are needed to confirm findings and to evaluate the impact of obesity on breast cancer subtypes.

Glucose promotes breast cancer aggression and reduces metformin efficacy

Metformin treatment has been associated with a decrease in breast cancer risk and improved survival. Metformin induces complex cellular changes, resulting in decreased tumor cell proliferation, reduction of stem cells, and apoptosis. Using a carcinogen-induced rodent model of mammary tumorigenesis, we recently demonstrated that overfeeding in obese animals is associated with a 50% increase in tumor glucose uptake, increased proliferation, and tumor cell reprogramming to an "aggressive" metabolic state. Metformin significantly inhibited these pro-tumorigenic effects. We hypothesized that a dynamic relationship exists between chronic energy excess (glucose by dose) and metformin efficacy/action. Media glucose concentrations above 5 mmol/L was associated with significant increase in breast cancer cell proliferation, clonogenicity, motility, upregulation/activation of pro-oncogenic signaling, and reduction in apoptosis. These effects were most significant in triple-negative breast cancer (TNBC) cell lines. High-glucose conditions (10 mmol/L or above) significantly abrogated the effects of metformin. Mechanisms of metformin action at normal vs. high glucose overlapped but were not identical; for example, metformin reduced IGF-1R expression in both the HER2+ SK-BR-3 and TNBC MDA-MB-468 cell lines more significantly at 5, as compared with 10 mmol/L glucose. Significant changes in gene profiles related to apoptosis, cellular processes, metabolic processes, and cell proliferation occurred with metformin treatment in cells grown at 5 mmol/L glucose, whereas under high-glucose conditions, metformin did not significantly increase apoptotic/cellular death genes. These data indicate that failure to maintain glucose homeostasis may promote a more aggressive breast cancer phenotype and alter metformin efficacy and mechanisms of action.

Proliferative activity in Libyan breast cancer with comparison to European and Central African patients

Background. We evaluated the relation of proliferative indices with clinicopathological features and prognosis in breast cancer (BC) of Libyan female patients. The data were compared with corresponding results in Finland and Nigeria. Patients and Methods. Histological samples of breast cancer from 130 patients were retrospectively studied. Mitotic activity index (MAI) and standardized mitotic index (SMI) were estimated. Results. There were statistically significant correlations between the proliferative indices and most clinicopathological features, with the strongest association observed for histological grade (P = 0.01 for SMI and P = 0.003 for MAI). The proliferative differences between Libyan, Nigerian, and Finnish population were prominent. The mean values of SMI and MAI in Libyan BC patients were 32.1 mitotic figures per square millimeter and 27.3 mitotic figures per 10 high-power fields, respectively. This is clearly lower than those in Nigeria but much higher than those in Finland. The differences between countries are seen in whole material and are also present in subgroups. The results indicated that mitotic activities can be reliable prognostic indicators in Libyan BCs, as they were among Finnish and Nigerian females. Univariate and multivariate analyses found at cut-offs of 19 and 44 mitosis/mm² of SMI were the most significant prognostic factors. Conclusions. Proliferative indices with careful estimation of the MAI and SMI could be applied as quantitative criteria for Libyan BC to separate the patients into good, moderate, and bad prognosis groups.

Overweight, obesity and risk of premenopausal breast cancer according to ethnicity: a systematic review and dose-response meta-analysis

The association of overweight and obesity with premenopausal breast cancer remained unclear, ethnicity could play a role. A MEDLINE and PUBMED search of all studies on obesity and premenopausal breast cancer published from 2000 to 2010 was conducted. Dose-response meta-analysis was used to determine the risk of premenopausal breast cancer associated with different anthropometric measurements in different ethnic groups. For body mass index (BMI), each 5 kg m(-2) increase was inversely associated with the risk of premenopausal breast cancer (RR = 0.95, 95% confidence interval [CI]: 0.94, 0.97). After stratification by ethnicity, the inverse association remained significant only among Africans (RR = 0.95, 95% CI: 0.91, 0.98) and Caucasians (RR = 0.93, 95% CI: 0.91, 0.95). In contrast, among Asian women, a significant positive association was observed. For waist-to-hip ratio (WHR), each 0.1 unit increase was positively associated with premenopausal breast cancer (RR = 1.08, 95% CI: 1.01, 1.16); the largest effect was detected in Asian women (RR = 1.19, 95% CI: 1.15, 1.24), while small effects of 5% and 6% were observed in African and Caucasian women, respectively. Our results suggest the importance of considering both fat distribution and ethnicity when studying premenopausal breast cancer.

Lifestyle behaviors of African American breast cancer survivors: a Sisters Network, Inc. study

INTRODUCTION

African American breast cancer survivors experience poor cancer outcomes that may, in part, be remedied by healthy lifestyle choices. Few studies have evaluated the health and lifestyle behaviors of this population. The purpose of this study was to characterize the health and lifestyle habits of African American breast cancer survivors and evaluate the socio-demographic and medical correlates of these behaviors.

METHODS

A total of 470 African American breast cancer survivors (mean age = 54 years) participated in an online survey. All participants completed measures assessing medical and demographic characteristics, physical activity, and sedentary behavior. Chi-square tests for association, nonparametric tests, and logistic regression models were used to assess associations. All statistical tests were two sided.

RESULTS

Almost half (47%) of the women met the current guidelines for physical activity, almost half (47%) were obese, and many reported having high blood pressure (53%) or diabetes (21%). The prevalence of high blood pressure, diabetes, and high cholesterol increased by age (P<0.001), and obese women had a higher prevalence of high blood pressure (63% vs. 44%) and diabetes (21% vs. 12%) than did non-obese women (all P<0.05). Obese women participated in significantly fewer total minutes of physical activity per week (100 minutes/week) than did non-obese women (150 minutes/week; P<0.05). The number of comorbid conditions was associated with increased odds for physical inactivity (odds ratio = 1.40) and obesity (odds ratio = 2.22).

CONCLUSION

Many African American breast cancer survivors had chronic conditions that may be exacerbated by poor lifestyle choices. Our results also provide evidence that healthy lifestyle interventions among obese African American breast cancer survivors are urgently needed.

Minireview: Obesity and breast cancer: a tale of inflammation and dysregulated metabolism

In addition to the spectrum of conditions known collectively as the Metabolic Syndrome, obesity is now recognized to be associated with increased risk of several cancers including colon, endometrial, and breast cancer. Obesity and carcinogenesis share 2 characteristics in common. On the one hand, they involve inflammatory pathways, and on the other hand, they involve dysregulated metabolism. In this review we focus on postmenopausal breast cancer and discuss the metabolic and cellular mechanisms whereby obesity and breast cancer are related. Because a majority of postmenopausal breast tumors are estrogen responsive, we include a discussion of the action of obesity-related factors on estrogen formation within the breast.

Associations between body size and serum estradiol and sex hormone-binding globulin levels in premenopausal African American women

CONTEXT

African American (AA) women have the highest rates of premenopausal breast cancer; however, it is unclear whether body size contributes to the hormonal patterns potentially associated with increased breast cancer risk in these women.

OBJECTIVE

To characterize the association between body size and serum levels of estradiol and sex hormone-binding globulin (SHBG) levels in a sample of premenopausal AA women.

DESIGN

A total of 164 premenopausal AA women who were not pregnant or breastfeeding were recruited for this study. Serum samples were collected during the early follicular phase, and trained staff collected body size measurements. Multiple linear regression models were performed to assess potential associations.

MAIN OUTCOME MEASURES

Serum estradiol and SHBG levels.

RESULTS

Many (81%) of the women enrolled were overweight or obese. Both waist-to-hip ratio (WHR) (β = 2.68, P = .008) and waist circumference (WC) (β = 2.02, P = .046) were positively associated with higher levels of estradiol. All measures of body was significantly and inversely associated with SHBG levels (all P < .05).

CONCLUSIONS

Premenopausal AA women with higher WHR or larger WC may have higher levels of estradiol and lower levels of SHBG. Thus, WHR or WC may be better indicators for assessing hormonal patterns implicated in breast cancer pathogenesis in these women.

Risk factors for premenopausal breast cancer: a case-control study in Uruguay

In order to thoroughly analyze risk factors of breast cancer (BC) in premenopausal Uruguayan women, a case-control study was carried out at the Pereira Rossell Women's Hospital, Montevideo, where 253 incident BC cases and 497 frequency-matched healthy controls were interviewed on menstrual and reproductive story, were administered a short food frequency questionnaire and undertook a series of body measurements necessary to calculate body composition and somatotype. Odds ratio (OR) coefficients were taken as estimates of relative risk derived from unconditional logistic regression. Among the classical risk factors, only the family history of BC in first degree relatives was significantly associated with risk of premenopausal BC (OR=2.20, 95% CI 1.33-3.62). Interestingly, this risk factor was found to be stronger in women of ages >40 (OR=4.05, 95% CI 2.10-7.81), late menarche (OR= 2.39, 95% CI 1.18-4.85), early age for their first delivery (OR=3.02, 95% CI 1.26-7.22), short time between menarche and first delivery (OR=3.22, 95% CI 1.29-8.07), and with high parity (OR=4.10, 95% CI 1.79-9.36), although heterogeneity was detected only for age and parity. High consumption of red meat was positively associated with the disease risk (OR=2.20, 95% CI 1.35-3.60), in the same way as fried foods (OR=1.79, 95% CI 1.12-2.84). Conversely, a high intake of plant foods displayed a protective effect (OR=0.41, 95% CI 0.26-0.65). Except for hypertension (OR=1.55, 95% CI 1.03-2.35), none of the analyzed components of metabolic syndrome were associated to BC risk. Particular increases of risk for premenopausal BC were found for family history in first degree relatives in certain subsets derived from the menstrual-reproductive history. Preventive strategies could broaden their scope if new studies confirm the present results, in view of the limited prevention measures that premenopausal BC currently has.

Role of obesity in the risk of breast cancer: lessons from anthropometry

An estimated 1.38 million new cases of breast cancer (BC) are diagnosed each year in women worldwide. Of these, the majority are categorized as invasive ductal cell carcinoma. Subgroups of BC are frequently distinguished into five "intrinsic" subtypes, namely, luminal A, luminal B, normal-like, HER2-positive, and basal-like subtypes. Epidemiological evidence has shown that anthropometric factors are implicated in BC development. Overall consistent positive associations have been observed between high body mass index (BMI) and waist-to-hip ratio (WHR) and the risk of BC among postmenopausal women, while conflicting results persist for premenopausal BC, both for BMI and for other anthropometric parameters as well as across ethnic groups. Furthermore, some evidence suggests that body size, body shape, and weight gain during childhood or adolescence may play a role in the risk of BC. In this paper, we describe the evidence linking anthropometric indices at different ages and BC risk, in order to improve our understanding of the role of body fat distribution in the risk of BC, investigate differences in these associations according to menopausal status and ethnic groups, and discuss the potential biological mechanisms linking body size and BC risk.

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.

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.

Body mass index and the risk for developing invasive breast cancer among high-risk women in NSABP P-1 and STAR breast cancer prevention trials

High body mass index (BMI) has been associated with an increased risk for breast cancer among postmenopausal women. However, the relationship between BMI and breast cancer risk in premenopausal women has remained unclear. Data from two large prevention trials conducted by the National Surgical Adjuvant Breast and Bowel Project (NSABP) were used to explore the relationship between baseline BMI and breast cancer risk. The analyses included 12,243 participants with 253 invasive breast cancer events from the Breast Cancer Prevention Trial (P-1) and 19,488 participants with 557 events from the Study of Tamoxifen and Raloxifene (STAR). Both studies enrolled high-risk women (Gail score ≥ 1.66) with no breast cancer history. Women in P-1 were pre- and postmenopausal, whereas women in STAR (P-2) were all postmenopausal at entry. Using Cox proportional hazards regression, we found slight but nonsignificant increased risks of invasive breast cancer among overweight and obese postmenopausal participants in STAR and P-1. Among premenopausal participants, an increased risk of invasive breast cancer was significantly associated with higher BMI (P = 0.01). Compared with BMI less than 25, adjusted HRs for premenopausal women were 1.59 for BMI 25 to 29.9 and 1.70 for BMI 30 or more. Our investigation among annually screened, high-risk participants in randomized, breast cancer chemoprevention trials showed that higher levels of BMI were significantly associated with increased breast cancer risk in premenopausal women older than 35 years, but not postmenopausal women.

The role of anthropometric and nutritional factors on breast cancer risk in African-American women

OBJECTIVE

While the role of nutrition, physical activity and body size on breast cancer risk has been extensively investigated, most of these studies were conducted in Caucasian populations. However, there are well-known differences in tumour biology and the prevalence of these factors between African-American and Caucasian women. The objective of the present paper was to conduct a review of the role of dietary factors, anthropometry and physical activity on breast cancer risk in African-American women.

DESIGN

Twenty-six research articles that presented risk estimates on these factors in African-American women and five articles involving non-US black women were included in the current review.

SETTING

Racial disparities in the impact of anthropometric and nutritional factors on breast cancer risk.

SUBJECTS

African-American and non-US black women.

RESULTS

Based on the few studies that presented findings in African-American women, an inverse association with physical activity was found for pre- and postmenopausal African-American women, while the association for anthropometric and other dietary factors, such as alcohol, was unclear. Studies assessing the effect by molecular subtypes in African-American women were too few and based on sample sizes too small to provide definitive conclusions.

CONCLUSIONS

The effect of certain nutrition and lifestyle factors on breast cancer in African-American women is not starkly distinct from those observed in white women. However, there is an enormous need for further research on this minority group to obtain more confirmatory findings.

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.

Lifestyle behaviors in black and white women with a family history of breast cancer

OBJECTIVES

To examine lifestyle behaviors among non-Hispanic black and white women with a family history of breast cancer and determine the extent to which they meet American Cancer Society (ACS) Nutrition and Physical Activity Recommendations for Breast Cancer Prevention.

METHOD

Cross-sectional data from 44,364 women enrolled in the Sister Study (2009), a study of sisters of women with breast cancer within the U.S., were analyzed. Descriptive statistics and chi-square analyses were used to examine body mass index and lifestyle behaviors (e.g., exercise, diet, and smoking) and to determine percentages of women meeting ACS recommendations.

RESULTS

Black women consumed a lower percentage of calories from fat (mean 36.90% vs. 37.17%) and were more likely to meet ACS alcohol recommendations than whites. White women consumed more fruits and vegetables/day (mean 4.81 vs. 4.41) than black women and were more likely to meet ACS guidelines for physical activity (26.4% vs. 18.2%) and body mass index (42.5% vs. 16.7%).

CONCLUSION

Despite an elevated risk for breast cancer due to a family history of breast cancer, the majority of women were no more likely than women in the general population to engage in healthy lifestyle behaviors. These women may benefit from lifestyle behavior risk-reduction counseling.

Common genetic variation in adiponectin, leptin, and leptin receptor and association with breast cancer subtypes

Adipocytokines are produced by visceral fat, and levels may be associated with breast cancer risk. We investigated whether single nucleotide polymorphisms (SNPs) in adipocytokine genes adiponectin (ADIPOQ), leptin (LEP), and the leptin receptor (LEPR) were associated with basal-like or luminal A breast cancer subtypes. 104 candidate and tag SNPs were genotyped in 1776 of 2022 controls and 1972 (200 basal-like, 679 luminal A) of 2311 cases from the Carolina Breast Cancer Study (CBCS), a population-based case-control study of whites and African Americans. Breast cancer molecular subtypes were determined by immunohistochemistry. Genotype odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression. Haplotype ORs and 95% CIs were estimated using Hapstat. Interactions with waist-hip ratio were evaluated using a multiplicative interaction term. Ancestry was estimated from 144 ancestry informative markers (AIMs), and included in models to control for population stratification. Candidate SNPs LEPR K109R (rs1137100) and LEPR Q223R (rs1137101) were positively associated with luminal A breast cancer, whereas ADIPOQ +45 T/G (rs2241766), ADIPOQ +276 G/T (rs1501299), and LEPR K656N (rs8129183) were not associated with either subtype. Few patterns were observed among tag SNPs, with the exception of 3 LEPR SNPs (rs17412175, rs9436746, and rs9436748) that were in moderate LD and inversely associated with basal-like breast cancer. However, no SNP associations were statistically significant after adjustment for multiple comparisons. Haplotypes in LEP and LEPR were associated with both basal-like and luminal A subtypes. There was no evidence of interaction with waist-hip ratio. Data suggest associations between LEPR candidate SNPs and luminal A breast cancer in the CBCS and LEPR intron 2 tag SNPs and basal-like breast cancer. Replication in additional studies where breast cancer subtypes have been defined is necessary to confirm these potential associations.

Obesity is associated with breast cancer in African-American women but not Hispanic women in South Los Angeles

BACKGROUND

Obesity is considered a risk factor for breast cancer. Modifying life styles that reduce obesity offers the potential for prevention and improved outcomes from cancer. The effects of obesity and breast cancer among African-American women and Hispanic women have been explored in a limited number of studies. The objective of the current study was to investigate the association of obesity with breast cancer in a minority cohort.

METHODS

This was a cross-sectional study of 471 African-American and Hispanic women with and without breast cancer in South Los Angeles. Data regarding body mass index (BMI) and clinical factors were obtained by medical record abstraction. Data were assessed using logistic regression with multivariate analysis. Kaplan-Meier survival analysis was used to assess disease-free survival.

RESULTS

Women with breast cancer were more likely to be obese (BMI >30 kg/m(2)) than women without breast cancer (odds ratio [OR], 2.0; P = .01). There was a significant association of being overweight or obese and breast cancer among postmenopausal women (OR, 2.3 [P = .03] and 2.9 [P < .01], respectively). The association between obesity and breast cancer was significant only among African-American women (OR, 2.70; P < .01) and was especially significant among postmenopausal African-American women (OR, 4.8; P < .01). There was a borderline significant association between obesity and later disease stage at diagnosis (P = .06). An association also was observed between higher BMI (for cutoff points of both 30 kg/m(2) and 28 kg/m(2)) and poorer disease-free survival (P = .045 and P = .019, respectively).

CONCLUSIONS

The current data suggested an association between obesity and breast cancer, especially among postmenopausal women and most significantly in the African-American cohort.

Adult body size, hormone receptor status, and premenopausal breast cancer risk in a multiethnic population: the San Francisco Bay Area breast cancer study

Large body size has been associated with a reduced risk of premenopausal breast cancer in non-Hispanic white women. Data on other racial/ethnic populations are limited. The authors examined the association between premenopausal breast cancer risk and adult body size in 672 cases and 808 controls aged ≥35 years from a population-based case-control study conducted in 1995-2004 in the San Francisco Bay Area (Hispanics: 375 cases, 483 controls; African Americans: 154 cases, 160 controls; non-Hispanic whites: 143 cases, 165 controls). Multivariate adjusted odds ratios and 95% confidence intervals were calculated using unconditional logistic regression. Height was associated with increased breast cancer risk (highest vs. lowest quartile: odds ratio = 1.77, 95% confidence interval: 1.23, 2.53; P(trend) < 0.01); the association did not vary by hormone receptor status or race/ethnicity. Body mass index (measured as weight (kg) divided by height (m) squared) was inversely associated with risk in all 3 racial/ethnic groups, but only for estrogen receptor- and progesterone receptor-positive tumors (body mass index ≥30 vs. <25: odds ratio = 0.42; 95% confidence interval: 0.29, 0.61). Other body size measures (current weight, body build, adult weight gain, young adult weight and body mass index, waist circumference, and waist-to-height ratio) were similarly inversely associated with risk of estrogen receptor- and progesterone receptor-positive breast cancer but not estrogen receptor- and progesterone receptor-negative disease. Despite racial/ethnic differences in body size, inverse associations were similar across the 3 racial/ethnic groups when stratified by hormone receptor status.

Case-control study of body size and breast cancer risk in Nigerian women

Previous studies have shown that weight is inversely associated with premenopausal breast cancer and positively associated with postmenopausal disease. Height has been shown to be positively correlated with breast cancer risk, but the association was not conclusive for premenopausal women. These previous studies were conducted primarily in Western countries, where height is not limited by nutritional status during childhood. The authors assessed the association between breast cancer and anthropometric measures in the Nigerian Breast Cancer Study (Ibadan, Nigeria). Between 1998 and 2009, 1,233 invasive breast cancer cases and 1,101 controls were recruited. The multivariate-adjusted odds ratio for the highest quartile group of height relative to the lowest was 2.03 (95% confidence interval (CI): 1.51, 2.72; P-trend < 0.001), with an odds ratio of 1.22 (95% CI: 1.14, 1.32) for each 5-cm increase, with no difference by menopausal status. Comparing women with a body mass index in the lowest quartile group, the adjusted odds ratio for women in the highest quartile category was 0.72 (95% CI: 0.54, 0.94; P-trend = 0.009) for premenopausal and postmenopausal women. Influence of height on breast cancer risk was quite strong in this cohort of indigenous Africans, which suggests that energy intake during childhood may be important in breast cancer development.

Hormonal and metabolic modulation through nutrition: towards a primary prevention of breast cancer

Breast cancer (BC) is a polygenic and multifactorial disease for which estrogens have been recognized as the main risk factor, and for which lifestyle plays a key role. Previous epidemiologic cancer research performed in Uruguayan population delimited its dietary and anthropometric profiles. Recognizing the difficulty for universalizing a nutritional basis for prevention due to different eating patterns among regions and countries, we summarize the existent knowledge linking nutrition, estrogens, metabolism and BC. As an attempt towards primary prevention of BC, we present recommendations mainly based on country-specific research findings and modifiable putative risk and protective factors, proposing to modify the intake of meats and other fatty foods--especially sources of Ω-6 and Ω-3 fatty acids--adding olive oil, selected vegetables, citrus fruits and working towards adequate body fat/muscle proportions. From a medical and ethical viewpoint, it is justified to recommend certain nutritional changes to women, because no adverse side effects are expected to occur.

A case-control study of body mass index and breast cancer risk in white and African-American women

OBJECTIVE

Large body size has been associated with decreased risk of breast cancer in premenopausal women but with increased risk in postmenopausal women. Limited information is available about African-American women and differences by estrogen and progesterone receptor status.

METHODS

We analyzed data from the Women's Contraceptive and Reproductive Experiences Study among 3,997 white and African-American breast cancer case patients diagnosed in 1994 to 1998 and 4,041 control participants ages 35 to 64 years. We calculated multivariate odds ratios (OR) as measures of relative risk of breast cancer associated with self-reported body mass index (BMI) at age 18 and 5 years before diagnosis (recent BMI).

RESULTS

Risk tended to decrease with increasing BMI at age 18 years in all women [OR(BMI > or = 25 kg/m(2) versus < 20 kg/m(2)) = 0.76; 95% confidence interval (CI), 0.63-0.90; P(trend) = 0.005] and with recent BMI in premenopausal women (OR(BMI > or = 35 kg/m(2) versus < 25 kg/m(2)) = 0.81; 95% CI, 0.61-1.06; P(trend) = 0.05), unmodified by race. Among postmenopausal white but not African-American women, there was an inverse relation between recent BMI and risk. High recent BMI was associated with increased risk of estrogen receptor- and progesterone receptor-positive tumors among postmenopausal African-American women (OR(BMI > or = 35 kg/m(2) versus < 25 kg/m(2)) = 1.83; 95% CI, 1.08-3.09; P(trend) = 0.03).

CONCLUSION

Among women at age 35 to 64 years, BMI at age 18 years is inversely associated with risk of breast cancer, but association with recent BMI varies by menopause status, race, and hormone receptor status.

IMPACT

Our findings indicate that studies of BMI and breast cancer should consider breast cancer subtypes.

Racial differences in the association between body mass index and serum IGF1, IGF2, and IGFBP3

African-American (AA) race/ethnicity, lower body mass index (BMI), and higher IGF1 levels are associated with premenopausal breast cancer risk. This cross-sectional analysis investigated whether BMI or BMI at age 21 years contributes to racial differences in IGF1, IGF2, IGF-binding protein 3 (IGFBP3), or free IGF1. Participants included 816 white and 821 AA women between ages 40 and 79 years across a wide BMI range (18.5-40 kg/m(2)). Compared with white women, AA women had higher mean IGF1 (146.3 vs 134.4 ng/ml) and free IGF1 (0.145 vs 0.127) levels, and lower IGF2 (1633.0 vs 1769.3 ng/ml) and IGFBP3 (3663.3 vs 3842.5 ng/ml) levels (all P<0.01; adjusted for age, height, BMI, BMI at age 21 years, and menopausal status). Regardless of race, IGF1 and free IGF1 levels rose sharply as BMI increased to 22-24 kg/m(2), and then declined thereafter, while IGF2 and IGFBP3 levels tended to rise with BMI. In contrast, BMI at age 21 years was inversely associated with all IGF levels, but only among white women (P-interaction=0.01). With the decline in IGF1 with BMI at age 21 years among whites, racial differences in IGF1 significantly increased among women who were obese in early adulthood. In summary, BMI was associated with IGF1 levels regardless of race/ethnicity, while obesity during childhood or young adulthood may have a greater impact on IGF1 levels among white women. The effects of obesity throughout life on the IGF axis and racial differences in breast cancer risk require study.

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.

Through the Looking Glass at Early-Life Exposures and Breast Cancer Risk

The global increase in the proportion of women diagnosed with breast cancer, inadequate access to screening and high cost of treatment for breast cancer argue strongly for a greater focus on preventive strategies. But at what age is it appropriate to begin targeting preventive approaches? The recognized role of perinatal nutrition in neurologic development and the relation of maternal nutritional status to birthweight and subsequent risk of hypertension, diabetes, and cardiovascular disease identify pregnancy and early childhood as potential phases for prevention. This review examines indicators of hormonal and nutritional exposures in early life and breast cancer risk through the lens of the life course paradigm integrated with maternal and child health research and methodology. Compared to women who were normal birthweight (2500-3999 g), women who weighed>or=4,000 g at birth have a 20 percent to 5-fold increased risk of premenopausal breast cancer. Women born preterm and likely to be small- or large-for-date also have an increased risk. Birth length is directly associated with risk and has a larger magnitude of effect than birthweight. Prior preeclamptics and their daughters have a lower risk of breast cancer than comparable normotensives. An association between infant feeding practices and breast cancer is unclear without improved exposure assessment and analysis. Rapid childhood and pubertal linear growth increases breast cancer risk, while greater body fat over the same periods reduces risk. Growth data thus far have not been calculated in Z-scores from reference growth curves for comparison across studies. Events and secular trends influencing birth cohorts may not be adequately addressed, thereby limiting the interpretation and implications of the findings. Research in nonhuman primates may help uncover underlying mechanisms.

Body size and breast cancer in a black population--the Barbados National Cancer Study

OBJECTIVE

To evaluate the relationship between body size and incident breast cancer in an African-origin Caribbean population.

METHODS

This investigation is based on 222 incident breast cancer cases and 454 controls from the Barbados National Cancer Study (BNCS) in whom body size variables that included height, weight, body-mass index (BMI), waist and hip circumferences (WC, HC), and waist-hip ratio (WHR) were compared. Multivariate-adjusted logistic regression analyses were performed and the findings are presented as odds ratios (ORs) with 95% confidence intervals (CI).

RESULTS

Although 33% of cases and 39% of controls were obese (BMI > or = 30 kg/m(2)), BMI was not found to be a significant predictor of breast cancer in the multivariate analyses. Tall stature increased risk among women > or =50 years (OR = 2.16, 95% CI (1.02, 4.58)), and a dual effect with age was suggested for both WC and WHR (decreased risk for those aged < or =50 years; increased risk among those > or =50 years).

CONCLUSIONS

Body size appears to influence the risk of breast cancer in this population of African origin. The BNCS data suggest that a few, but not all body size factors play a role in breast cancer risk, and that age may affect these relationships.

Triple-negative breast cancers are increased in black women regardless of age or body mass index

Introduction

We investigated clinical and pathologic features of breast cancers (BC) in an unselected series of patients diagnosed in a tertiary care hospital serving a diverse population. We focused on triple-negative (Tneg) tumours (oestrogen receptor (ER), progesterone receptor (PR) and HER2 negative), which are associated with poor prognosis.

Methods

We identified female patients with invasive BC diagnosed between 1998 and 2006, with data available on tumor grade, stage, ER, PR and HER2 status, and patient age, body mass index (BMI) and self-identified racial/ethnic group. We determined associations between patient and tumour characteristics using contingency tables and multivariate logistic regression.

Results

415 cases were identified. Patients were racially and ethnically diverse (born in 44 countries, 36% white, 43% black, 10% Hispanic and 11% other). 47% were obese (BMI > 30 kg/m2). 72% of tumours were ER+ and/or PR+, 20% were Tneg and 13% were HER2+. The odds of having a Tneg tumour were 3-fold higher (95% CI 1.6, 5.5; p = 0.0001) in black compared with white women. Tneg tumours were equally common in black women diagnosed before and after age 50 (31% vs 29%; p = NS), and who were obese and non-obese (29% vs 31%; p = NS). Considering all patients, as BMI increased, the proportion of Tneg tumours decreased (p = 0.08).

Conclusions

Black women of diverse background have 3-fold more Tneg tumours than non-black women, regardless of age and BMI. Other factors must determine tumour subtype. The higher prevalence of Tneg tumours in black women in all age and weight categories likely contributes to black women's unfavorable breast cancer prognosis.