Breast White Adipose Tissue Inflammation Research Articles

Prevalence and patterns of breast white adipose tissue inflammation among American Black women and indigenous Nigerian women with early-stage breast cancer.

e12560 Background: Racial disparities in breast cancer outcomes pose a major public health challenge. Complex interactions between social determinants of health and tumor biology, mediated by obesity and adiposity, may play an important role in these disparities. White adipose tissue inflammation (WATi) of the breast, which is histologically defined by the presence of crown-like structures (CLS-B), occurs in the setting of excess adiposity and promotes tumor growth via elevated levels of aromatase, proinflammatory growth factors, and metabolic dysregulation. Here we examined relationships between race, body mass index (BMI), and WATi in two cohorts of patients with early-stage breast cancer: 1) American Black women and 2) indigenous Nigerian women. Methods: Non-tumor breast WAT specimens were collected from patients undergoing mastectomy for treatment or prevention of breast cancer at Memorial Sloan Kettering Cancer Center (MSK) in the US and Obafemi Awolowo University Teaching Hospital (OAUTH) in Nigeria. WATi was defined by the presence of CLS-B as detected by CD68 immunostaining. All tissue analyses were performed at MSK. Associations among BMI and WATi were tested within each cohort using Kendall’s tau rank correlation and compared between cohorts using Pearson's Chi-squared test. Results: A total of 224 American women were enrolled at MSK between 2011-2018, of whom 39 self-reported Black race. At OAUTH, 97 Nigerian women were enrolled between 2018-2022. Invasive carcinoma was present in 32 American Blacks and 97 Nigerians. Of those with invasive carcinoma, the prevalence of WATi among American Black women was 72% vs. 37% in the Nigerian cohort ( p<0.001). In the US cohort, there was no significant difference between the prevalence of WATi among Black vs. non-Black patients (72% vs. 62%; p=0.3). 44% of American Blacks were obese and 34% overweight compared with 27% and 39% of Nigerians, respectively (p=0.07). The prevalence of WATi varied by BMI category within each cohort, as shown. Overweight/obesity was associated with WATi in the Nigerian (p=0.009) and American cohorts (p<0.001); a trend was observed in the American Black subgroup (p=0.13). Conclusions: Breast WATi and obesity were more prevalent among American Black women with breast cancer compared with Nigerian women. These findings highlight the need for further investigation of environment, lifestyle patterns, and body composition differences between indigenous and diaspora populations. [Table: see text]

Abstract P2-08-05: Plasma lipidomics analysis to identify potential non-invasive biomarkers for breast white adipose inflammation and aromatase expression levels

Abstract Background: The presence of white adipose tissue inflammation (WATi) in the breast has been associated with increased breast cancer risk and a worse clinical course. Elevated body mass index (BMI) and the post-menopausal state are both associated with breast WATi. Breast WATi has also been associated with increased expression of aromatase, the rate-limiting enzyme for estrogen biosynthesis. Currently, WATi is diagnosed in surgical samples of breast tissue by the identification of crown-like structures (CLS), which are comprised of a dead or dying adipocyte enveloped by macrophages. In contrast to surgical specimens, core biopsies have been shown to be inadequate for assessing WATi. Hence, there is an unmet need for strategies to non-invasively diagnose WATi. Here we used a novel lipidomics platform to identify potential non-invasive blood signatures of breast WATi. Methods: We conducted a cross-sectional study which included 100 patients who underwent mastectomy for breast cancer treatment or risk reduction. WATi was detected by CD68 immunohistochemistry to identify CLS. Breast aromatase expression levels were measured by qPCR. Clinicopathologic data were abstracted from electronic medical records. Lipidomic data were measured from blood plasma in collaboration with Waters Technologies Corporation. Lipid levels in association with breast WATi (presence/absence) and levels of aromatase expression (high/low) in non-tumorous breast tissue were examined using Welch’s t-test. P-values were adjusted for multiple comparisons by controlling the false discovery rate (FDR) using the Benjamini-Hochberg method. A logistic regression model was used to develop predictive models that evaluated potential lipid biomarkers of the presence of breast WATi and high breast aromatase expression levels. Stepwise regression was used for variable selection. AUC of the ROC curves was used to evaluate the performance of the predictive models. Results: Among 140 lipids analyzed, 13 were identified to be associated with breast WATi (P<0.05, |log2FC|>0.3). Specifically, 8 lipids had lower levels, and 6 lipids had higher levels in patients with breast WATi compared to those without. Levels of 7 lipids were significantly higher in patients with an increased level of aromatase (P<0.05, |log2FC|>0.3). After variable selection, LPE(22:6) (P=0.018), LPE(20:3) ES-(P=0.006), along with menopausal status and BMI provided an 86.0% (95% CI, 77.6%-94.5%) accuracy in predicting higher breast aromatase levels. Combining the effect of two lipids improved the accuracy by 10.4%(P=0.030) compared to the model only using menopausal status and BMI. A model with 5 lipids and menopausal status provided an 88.8%(95% CI, 81.9%-95.8%) accuracy for predicting breast WATi. The model performance improved by 9.2% (P=0.026) compared to the model only using menopausal status and BMI. Conclusions: Our study identified several lipid species that showed significant changes in association with breast WATi and levels of aromatase expression. Further validation of these blood signatures could provide non-invasive assessment of WATi and aromatase levels. The availability of such a diagnostic algorithm could help, in turn, to both identify women at elevated risk for breast cancer and for monitoring the efficacy of interventions aimed at reducing inflammation and aromatase levels. Citation Format: Xiao Cai, Siqi Wei, Zizhuo Xu, Xi K Zhou, Andrew Peck, Steven Lai, Giorgis Isaac, Hernando Olivos, Nayasha Munjoma, Suraj Dhungana, Rob Plumb, Andrew J Dannenberg, Neil M Iyengar. Plasma lipidomics analysis to identify potential non-invasive biomarkers for breast white adipose inflammation and aromatase expression levels [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-08-05.

Blood biomarkers reflect the effects of obesity and inflammation on the human breast transcriptome.

Obesity is a risk factor for the development of post-menopausal breast cancer. Breast white adipose tissue (WAT) inflammation, which is commonly found in women with excess body fat, is also associated with increased breast cancer risk. Both local and systemic effects are probably important for explaining the link between excess body fat, adipose inflammation and breast cancer. The first goal of this cross-sectional study of 196 women was to carry out transcriptome profiling to define the molecular changes that occur in the breast related to excess body fat and WAT inflammation. A second objective was to determine if commonly measured blood biomarkers of risk and prognosis reflect molecular changes in the breast. Breast WAT inflammation was assessed by immunohistochemistry. Bulk RNA-sequencing was carried out to assess gene expression in non-tumorous breast. Obesity and WAT inflammation were associated with a large number of differentially expressed genes and changes in multiple pathways linked to the development and progression of breast cancer. Altered pathways included inflammatory response, complement, KRAS signaling, tumor necrosis factor α signaling via NFkB, interleukin (IL)6-JAK-STAT3 signaling, epithelial mesenchymal transition, angiogenesis, interferon γ response and transforming growth factor (TGF)-β signaling. Increased expression of several drug targets such as aromatase, TGF-β1, IDO-1 and PD-1 were observed. Levels of various blood biomarkers including high sensitivity C-reactive protein, IL6, leptin, adiponectin, triglycerides, high-density lipoprotein cholesterol and insulin were altered and correlated with molecular changes in the breast. Collectively, this study helps to explain both the link between obesity and breast cancer and the utility of blood biomarkers for determining risk and prognosis.

Effects of Adiposity and Exercise on Breast Tissue and Systemic Metabo-Inflammatory Factors in Women at High Risk or Diagnosed with Breast Cancer.

Excess body fat and sedentary behavior are associated with increased breast cancer risk and mortality, including in normal weight women. To investigate underlying mechanisms, we examined whether adiposity and exercise impact the breast microenvironment (e.g., inflammation and aromatase expression) and circulating metabo-inflammatory factors. In a cross-sectional cohort study, breast white adipose tissue (WAT) and blood were collected from 100 women undergoing mastectomy for breast cancer risk reduction or treatment. Self-reported exercise behavior, body composition measured by dual-energy x-ray absorptiometry (DXA), and waist:hip ratio were obtained prior to surgery. Breast WAT inflammation (B-WATi) was assessed by IHC and aromatase expression was assessed by quantitative PCR. Metabolic and inflammatory blood biomarkers that are predictive of breast cancer risk and progression were measured. B-WATi was present in 56 of 100 patients and was associated with older age, elevated BMI, postmenopausal status, decreased exercise, hypertension and dyslipidemia (Ps < 0.001). Total body fat and trunk fat correlated with B-WATi and breast aromatase levels (Ps < 0.001). Circulating C-reactive protein, IL6, insulin, and leptin positively correlated with body fat and breast aromatase levels, while negative correlations were observed for adiponectin and sex hormone binding globulin (P < 0.001). Inverse relationships were observed with exercise (Ps < 0.05). In a subgroup of 39 women with normal BMI, body fat levels positively correlated with B-WATi and aromatase expression (Ps < 0.05). In conclusion, elevated body fat levels and decreased exercise are associated with protumorigenic micro- and host environments in normal, overweight, and obese individuals. These findings support the development of BMI-agnostic lifestyle interventions that target adiposity. PREVENTION RELEVANCE: We report that individuals with high body fat and low exercise levels have breast inflammation, higher breast aromatase expression, and levels of circulating metabo-inflammatory factors that have been associated with increased breast cancer risk. These findings support interventions to lower adiposity, even among normal weight individuals, to prevent tumor growth.

Effects of obesity on breast aromatase expression and systemic metabo-inflammation in women with BRCA1 or BRCA2 mutations

Obesity is associated with an increased risk of breast cancer in post-menopausal women and decreased risk in pre-menopausal women. Conversely, in BRCA1/2 mutation carriers, pre-menopausal obesity is associated with early-onset breast cancer. Here we show that obese, pre-menopausal BRCA1/2 mutation carriers have increased levels of aromatase and inflammation in the breast, as occurs in post-menopausal women. In a prospective cohort study of 141 women with germline BRCA1 (n = 74) or BRCA2 (n = 67) mutations, leptin, and aromatase expression were higher in the breast tissue of obese versus lean individuals (P < 0.05). Obesity was associated with breast white adipose tissue inflammation, which correlated with breast aromatase levels (P < 0.01). Circulating C-reactive protein, interleukin-6, and leptin positively correlated with body mass index and breast aromatase levels, whereas negative correlations were observed for adiponectin and sex hormone-binding globulin (P < 0.05). These findings could help explain the increased risk of early-onset breast cancer in obese BRCA1/2 mutation carriers.

The Relationship Between White Adipose Tissue Inflammation and Overweight/Obesity in Chinese Female Breast Cancer: A Retrospective Study.

This study aims to investigate the relationship between breast white adipose tissue (WAT) inflammation and being overweight or obese, menopausal status, and metabolic syndrome-related indicators in breast cancer patients as well as the association between adipocyte size and the severity of WAT inflammation and body mass index (BMI). The crown-like structures (CLS-B) formed by macrophages surrounding dying or dead adipocytes can be used to identify breast WAT inflammation. In this study, breast WAT and fasting blood from 136 Chinese women with breast cancer were collected for analysis. Cluster of differentiation 68 (CD68) immunohistochemical staining was performed to identify CLS-B, and the adipocyte size was measured by hematoxylin and eosin staining. The results showed that breast WAT inflammation usually occurs in overweight/obese breast cancer patients, and the severity of inflammation is positively correlated with adipocyte hypertrophy. We did not observe a direct association between WAT inflammation and menopausal status. In addition, the presence of WAT inflammation is associated with abnormalities in circulating factors associated with metabolic syndrome such as higher serum lipid, glucose, and C-reactive protein levels. Overweight/obese breast cancer patients may be more prone to breast WAT inflammation and may be associated with abnormalities in circulatory markers associated with metabolic syndrome.

Improving risk assessment of obesity-associated breast cancer.

1544 Background: Elevated body mass index (BMI) is associated with increased risk of estrogen receptor (ER)-positive postmenopausal breast cancer. The risk is also elevated in women with a normal BMI but excess body fat. These risks may be driven by breast white adipose tissue inflammation (WATi), which is associated with elevated aromatase levels and systemic metabolic dysfunction (e.g. hyperinsulinemia). We hypothesized that body fat assessment is superior to BMI for detecting the pathophysiology that promotes obesity-related breast cancer, particularly among normal BMI women. Methods: Non-tumorous breast tissue was collected from women undergoing mastectomy for breast cancer treatment or prevention. Breast WATi was detected by the presence of crown-like structures in the breast, which are composed of a dead/dying adipocyte surrounded by CD68+ macrophages. Body composition was measured prior to mastectomy via dual energy X-ray absorptiometry. Exercise behavior was also assessed prior to surgery using the Godin Leisure Time Exercise Questionnaire. Associations among categorical variables were examined using Χ2 or Fisher’s exact test. Relationships between continuous variables were examined using the Spearman correlation. Results: From April 5, 2016 to August 31, 2018, 100 patients were enrolled; median age 49 (range 29 to 82) years. Breast WATi was present in 56/100 (56%) women and was associated with elevated BMI and body fat levels, breast adipocyte hypertrophy, postmenopausal status, metabolic syndrome and decreased physical activity (P &lt; 0.05). Among 39 women with normal BMI, breast WATi was present in 14 (36%) and was associated with elevated body fat levels, breast adipocyte hypertrophy, dyslipidemia, and decreased physical activity (P &lt; 0.05). There was no statistically significant association between BMI and breast WATi in the normal BMI group. Menopausal status and total fat mass had greater sensitivity and specificity for the detection of breast WATi compared to a BMI-based model (AUC 0.843 vs. 0.779, respectively). Conclusions: Measurement of body fat is superior to BMI for predicting breast inflammation, which has been shown to promote obesity-related breast cancer.

Abstract P5-07-05: Obesity, adipose inflammation, and race in patients with early stage breast cancer

Abstract Background: Elevated body mass index (BMI) is associated with increased risk of estrogen receptor-positive postmenopausal breast cancer. Mechanistically, most individuals with elevated BMI have breast white adipose tissue inflammation (WATi) which confers increased breast cancer risk, particularly in those with existing benign breast disease. Individuals with WATi have elevated in-breast expression of aromatase and several systemic changes that increase breast cancer risk, including hyperinsulinemia and higher levels of C-reactive protein. However, women with normal BMI but high levels of body fat are also likely to harbor WATi and are at increased risk of postmenopausal breast cancer. The accuracy of BMI for assessing adiposity and predicting obesity-related disorders, including cancer, varies across race and ethnicity. Whether the association between BMI and WATi varies by race is unknown. Here we aimed to characterize relationships among breast WATi and clinicopathologic features in a racially diverse cohort undergoing mastectomy for breast cancer treatment. Methods: Non-tumorous breast tissue and fasting blood were collected from women undergoing mastectomy for breast cancer treatment or prevention at a single center serving a racially diverse patient population. Breast WATi was detected by the presence of crown-like structures in the breast (CLS-B), which are composed of a dead/dying adipocyte surrounded by CD68+ macrophages. Clinicopathologic data were abstracted from electronic medical records. Associations among categorical variables were examined using Fisher's exact test. Relationships between continuous variables were examined using the Spearman correlation. Results: As of May 18, 2018 62 patients have been accrued; median age 55 (range 32 to 84). Self-reported race distribution was: 36 (58%) Asian, 5 African American (8%), 20 (32%) Caucasian, and 1 (2%) unknown. Breast tissue has been analyzed for WATi in 60 cases thus far. Clinicopathologic features stratified by the presence or absence of breast WATi are presented in. Breast WAT inflammation was associated with obesity (P=0.02) and a trend to association was observed with dyslipidemia (P&amp;lt;0.09). VariableBreast WATi Absent (n=25)Breast WATi Present (n=35)Age, years Median (range)51 (32 to 71)59 (36 to 80)BMI, kg/m2 Median (range)22.5 (18.1 to 35.3)28.0 (19.2 to 38.9)BMI Category Underweight1 (4%)0 (0%)Normal16 (64%)10 (29%)Overweight5 (20%)18 (51%)Obese3 (12%)7 (20%)Race, n (%) Asian15 (60%)19 (54%)African American2 (8%)3 (9%)Caucasian8 (32%)12 (34%)Unknown0 (0%)1 (3%)Menopausal Status, n (%) Pre10 (40%)12 (34%)Post15 (60%)23 (66%)Hypertension, n (%)7 (28%)16 (46%)Diabetes mellitus, n (%)0 (0%)5 (14%)Dyslipidemia, n (%)1 (4%)11 (31%) Conclusions: Breast adipose inflammation is associated with elevated BMI and possibly metabolic syndrome disorders in a racially diverse population. These findings are consistent with observations from predominantly Caucasian cohorts. Race-specific characteristics will also be examined. Study accrual is ongoing and updated results will be presented. Citation Format: Iyengar NM, Siegel B, Malik M, Giri DD, Tsai J, Hughes M, Adam A, Williams S, Zhou XK, Rodgers W, Ginter P, Patel A, Yong F, Cherian A, August P, Dannenberg AJ. Obesity, adipose inflammation, and race in patients with early stage breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-07-05.

Obesity-associated Breast Inflammation among Hispanic/Latina Breast Cancer Patients.

Breast white adipose tissue inflammation (BWATi) is associated with obesity and higher breast cancer risk among non-Hispanic white women. Obesity is prevalent in Hispanic/Latina patients with breast cancer, and the occurrence of BWATi in this population is not well-characterized. The association between BWATi and body mass index (BMI) was evaluated in Hispanic/Latina patients with breast cancer who underwent mastectomy. BWATi was defined as the presence of crown-like structures of the breast (CLS-B), detected by CD68 IHC in nontumor breast tissue. BWATi severity was quantified as number of CLS-B/cm2 Adipocyte diameter was measured using hematoxylin and eosin-stained breast tissue sections. Preoperative BMI (within 1 week prior to mastectomy) was categorized as normal (18.5-<25.0 kg/m2), overweight (25.0-<30.0 kg/m2), class I obesity (30.0-<35.0 kg/m2), and class II-III obesity (35.0 kg/m2 or above). Patient charts were abstracted to record clinicopathologic features and liver function tests <90 days before mastectomy. The study included 91 women (mean age 69 years; range 36-96 years). Prevalence of BWATi increased with BMI (24% in normal weight, 34% in overweight, 57% in class I obesity, and 65% in class II-III obesity; P trend <0.01). Severe BWATi (>0.27 CLS-B/cm2) was associated with higher BMI (P trend = 0.046) and greater adipocyte diameter (P = 0.04). Adjusting for BMI, neoadjuvant chemotherapy, and elevated alanine aminotransferase were associated with severe BWATi, and current smoking was associated with mild BWATi (all P < 0.05). BWATi was associated with higher BMI in Hispanic/Latina patients with breast cancer, consistent with previously described associations in other populations.

Adiposity, Inflammation, and Breast Cancer Pathogenesis in Asian Women.

Obesity is associated with white adipose tissue (WAT) inflammation in the breast, elevated levels of the estrogen biosynthetic enzyme, aromatase, and systemic changes that predispose to breast cancer development. We examined whether WAT inflammation and its associated systemic effects correlate with body fat levels in an Asian population where body mass index (BMI) is not an accurate assessment of obesity and cancer risk. We also investigated whether biologic differences could account for the greater proportion of premenopausal estrogen receptor (ER)-positive breast cancer in Asian versus Western countries. Breast WAT and fasting blood were prospectively collected from Taiwanese women undergoing mastectomy for breast cancer treatment. Body composition was measured in a subgroup using bioelectrical impedance analysis. WAT inflammation was defined by the presence of crown-like structures of the breast, which are composed of dead or dying adipocytes surrounded by macrophages. Findings were compared with U.S. Caucasian women. In the Taiwanese cohort (n = 72), breast WAT inflammation was present in 31 (43%) women and was associated with elevated BMI (P < 0.01) and increased levels of body fat (P < 0.01), C-reactive protein (P = 0.02), triglycerides (P < 0.01), insulin resistance scores (P = 0.04), and lower HDL cholesterol (P < 0.01). ER+ tumors were associated with greater body fat versus other subtypes (P = 0.03). Compared with U.S. Caucasians (n = 267), Taiwanese women had larger breast adipocytes despite lower BMI after adjusting for BMI and menopausal status (P = 0.01). A subclinical inflammatory state associated with increased adiposity and metabolic dysfunction could contribute to breast cancer pathogenesis in Asian women. Cancer Prev Res; 11(4); 227-36. ©2017 AACR.

Metabolic Obesity, Adipose Inflammation and Elevated Breast Aromatase in Women with Normal Body Mass Index.

Obesity is associated with breast white adipose tissue (WAT) inflammation, elevated levels of the estrogen biosynthetic enzyme, aromatase, and systemic changes that have been linked to the pathogenesis of breast cancer. Here, we determined whether metabolic obesity, including changes in breast biology and systemic effects, occurs in a subset of women with normal body mass index (BMI). Breast WAT and fasting blood were collected from 72 women with normal BMI (<25 kg/m2) undergoing mastectomy for breast cancer risk reduction or treatment. WAT inflammation was defined by the presence of crown-like structures of the breast (CLS-B) which are composed of dead or dying adipocytes surrounded by macrophages. Severity of inflammation was measured as CLS-B/cm2 The primary objective was to determine whether breast WAT inflammation is associated with aromatase expression and activity. Secondary objectives included assessment of circulating factors and breast adipocyte size. Breast WAT inflammation was present in 39% of women. Median BMI was 23.0 kg/m2 (range, 18.4-24.9 kg/m2) in women with breast WAT inflammation versus 21.8 kg/m2 (range, 17.3-24.6 kg/m2) in those without inflammation (P = 0.04). Breast WAT inflammation was associated with elevated aromatase expression and activity, which increased with severity of inflammation (P < 0.05). Breast WAT inflammation correlated with larger adipocytes (P = 0.01) and higher circulating levels of C-reactive protein, leptin, insulin, and triglycerides (P ≤ 0.05). A subclinical inflammatory state associated with elevated aromatase in the breast, adipocyte hypertrophy, and systemic metabolic dysfunction occurs in some normal BMI women and may contribute to the pathogenesis of breast cancer. Cancer Prev Res; 10(4); 235-43. ©2017 AACRSee related article by Berger, p. 223-25.

Menopause Is a Determinant of Breast Aromatase Expression and Its Associations With BMI, Inflammation, and Systemic Markers.

Most estrogen-dependent breast cancers occur after menopause, despite low levels of circulating estrogens. Breast expression of the estrogen-biosynthetic enzyme, aromatase, is proposed to drive breast cancer development after menopause. However, the effects of menopause on breast aromatase expression are unknown. To determine the effect of menopause on breast aromatase expression in relation to body mass index (BMI), white adipose tissue inflammation (WATi), and systemic markers of metabolic dysfunction. Cross-sectional study of 102 premenopausal (age 27 to 56) and 59 postmenopausal (age 45 to 74) women who underwent mastectomy for breast cancer treatment/prevention. Breast tissue was assessed for the presence of crown-like structures and the expression and activity of aromatase. Systemic markers examined include interleukin (IL)-6, insulin, glucose, leptin, adiponectin, high-sensitivity C-reactive protein (hsCRP), cholesterol, and triglycerides. Multivariable analysis was performed for aromatase messenger RNA (mRNA) in relation to BMI, WATi, and blood markers. Postmenopausal women had higher BMI and more breast WATi than premenopausal women. Fasting levels of IL-6, glucose, leptin, hsCRP, and homeostatic model assessment 2 insulin resistance score were higher in the postmenopausal group. BMI was positively correlated with aromatase mRNA in both pre- and postmenopausal women. Aromatase levels were higher in breast tissue of postmenopausal women, with levels being higher in inflamed vs noninflamed, independent of BMI. Adipocyte diameter and levels of leptin, hsCRP, adiponectin, and high-density lipoprotein cholesterol were more strongly correlated with aromatase in postmenopausal than premenopausal women. Elevated aromatase in the setting of adipose dysfunction provides a possible mechanism for the higher incidence of hormone-dependent breast cancer in obese women after menopause.

Abstract PD5-05: Metabolic obesity, adipose inflammation and aromatase: Potential drivers of breast cancer risk in women with normal body mass index

Abstract Background: Elevated body mass index (BMI) is associated with increased risk of postmenopausal breast cancer, which may be partly attributable to an inflammation-aromatase axis. Most individuals with elevated BMI harbor white adipose tissue inflammation (WATi), defined by the presence of crown-like structures in the breast (CLS-B). CLS-B are composed of a dead/dying adipocyte surrounded by CD68+ macrophages. This inflammation is associated with activation of NF-κB and elevated expression of aromatase, which could contribute to tumor development. Additionally, WATi correlates with several circulating changes, including hyperinsulinemia, which increase breast cancer risk. Although breast WATi correlates with rising BMI, it is also present in some normal BMI individuals. Beyond inherited germline syndromes, the etiology of breast cancer in individuals with normal BMI is not well understood. Here we examined the impact of breast WATi on breast aromatase expression and circulating factors in women with normal BMI. Methods: Non-tumorous breast tissue and fasting blood were collected from 72 women with BMI &amp;lt; 25 kg/m2 undergoing mastectomy at MSKCC. Breast inflammation was detected by the presence of CLS-B using CD68 immunohistochemistry. The primary objective was to determine if breast WATi in normal BMI individuals correlates with elevated aromatase levels in the breast, measured by qPCR, western blotting, immunofluorescence and enzyme activity. Secondary objectives included assessment of breast adipocyte size and circulating metabolic and inflammatory factors. Results: Breast inflammation was present in 39% of women. Median BMI was 23.0 (range 18.4 to 24.9) in women with breast WATi versus 21.8 (range 17.3 to 24.6) in those without inflammation (P=0.04). Aromatase mRNA expression was positively correlated with WATi (CLS-B/cm2; P=0.002). Those with severe WATi had highest aromatase mRNA levels, compared to those with no or mild WATi (P=0.005). Aromatase protein, assessed by measuring adipose stromal cell-specific immunofluorescence or western blotting, and activity were also higher in CLS-B+ cases compared to CLS-B- (P&amp;lt;0.001). Breast WATi correlated with larger adipocytes (P=0.01) and higher circulating levels of C-reactive protein, leptin, insulin, and triglycerides (P&amp;lt;0.05). Insulin resistance, characterized by the homeostasis model (HOMA2-IR), correlated with breast WATi (P=0.004). Finally, leptin, a known inducer of aromatase and driver of cancer growth, correlated with higher breast aromatase levels (P=0.02) and larger adipocytes (P&amp;lt;0.01). Conclusions: A metabolically unhealthy state occurs in women with inflamed breast adipose despite having a normal BMI. This subclinical inflammatory state is characterized by elevated aromatase in the breast, insulin resistance, and dysplipidemia. The presence of enlarged adipocytes in the breasts of normal BMI women with inflammation suggests a state of hyperadiposity which could not be predicted based on BMI alone. These findings indicate that normal BMI metabolic obesity may be associated with increased cancer risk. Our results suggest that objective measurements of adiposity rather than BMI may help to identify individuals at increased risk for disease. Citation Format: Iyengar NM, Brown KA, Zhou XK, Subbaramaiah K, Giri DD, Gucalp A, Howe LR, Zahid H, Bhardwaj P, Wendel NK, Falcone DJ, Morrow M, Wang H, Williams S, Pollak M, Hudis CA, Dannenberg AJ. Metabolic obesity, adipose inflammation and aromatase: Potential drivers of breast cancer risk in women with normal body mass index [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD5-05.

Menopause is a determinant of breast adipose inflammation.

Chronic inflammation is recognized as a risk factor for the development of several malignancies. Local white adipose tissue (WAT) inflammation, defined by the presence of dead or dying adipocytes encircled by macrophages that form crown-like structures (CLS), occurs in the breasts (CLS-B) of most overweight and obese women. Previously, we showed that the presence of CLS-B is associated with elevated tissue levels of proinflammatory mediators and aromatase, the rate-limiting enzyme for estrogen biosynthesis. The associated increased levels of aromatase in the breast provide a plausible mechanistic link between WAT inflammation and estrogen-dependent breast cancers. Thus, breast WAT inflammation could be relevant for explaining the high incidence of estrogen-dependent tumors with aging despite diminished circulating estrogen levels after menopause. To explore this possibility, we determined whether menopause in addition to body mass index (BMI) is associated with breast WAT inflammation among 237 prospectively enrolled women. The presence of CLS-B and its severity (CLS-B/cm(2)) as indicators of WAT inflammation correlated with menopausal status (P = 0.008 and P < 0.001) and BMI (P < 0.001 for both). In multivariable analyses adjusted for BMI, the postmenopausal state was independently associated with the presence (P = 0.03) and severity of breast WAT inflammation (P = 0.01). Mean adipocyte size increased in association with CLS-B (P < 0.001). Our findings demonstrate that breast WAT inflammation, which is associated with elevated aromatase levels, is increased in association with the postmenopausal state independent of BMI. Breast WAT inflammation, a process that can potentially be targeted, may help to explain the high incidence of estrogen-dependent tumors in postmenopausal women.

Abstract P4-04-12: Both metabolic syndrome and statin use are more common in women with breast inflammation

Abstract Background: Metabolic syndrome is associated with increased breast cancer (BC) risk. After menopause, obesity is associated with increased risk of hormone receptor (HR)-positive breast cancer. We demonstrated an obesity → inflammation → aromatase axis in breast white adipose tissue (WAT) where inflammation is defined by the presence of crown-like structures (CLS) consisting of a dead or dying adipocyte encircled by macrophages. CLS in the breast (CLS-B) are associated with elevated body mass index (BMI), postmenopausal status, increased adipocyte size, and increased tissue levels of proinflammatory mediators and aromatase. As obesity is a component of the metabolic syndrome and is associated with inflammation, we compared levels of relevant circulating factors in women with and without breast WAT inflammation. Methods: We prospectively collected paired WAT and fasting serum and plasma from women undergoing mastectomy at MSKCC. WAT inflammation was detected by CD68 immunohistochemistry to identify CLS-B by light microscopy. Plasma levels of glucose, insulin, hsCRP, leptin, adiponectin, and IL-6 were measured by ELISA. Serum levels of total cholesterol, triglycerides (TG), HDL and LDL cholesterol were determined. Insulin resistance (IR) was assessed using fasting plasma glucose and insulin levels via the updated Homeostasis Model Assessment (HOMA2-IR). Associations between CLS-B and clinicopathologic features, including medication usage, were analyzed by logistic regression and Fisher’s exact test. Differences in serum/plasma endpoints between subjects with and without CLS-B were evaluated using Student t-test and nonparametric Wilcoxon rank-sum test. Results: From 11/2011 – 3/2013 we accrued 100 patients (pts); median age 47 years (range 27 – 70). Overall, CLS-B were found in 52/100 (52%) pts: 18/19 (95%) obese pts, 17/33 (52%) overweight pts, and 17/48 (35%) normal BMI pts. A clinical diagnosis of dyslipidemia was present in 14/52 (27%) pts with CLS-B and 1/48 (2%) pts without CLS-B (P&amp;lt;0.001). CLS-B were found in 10/11 (91%) statin users, but in only 42/89 (47%) non-users (P=0.008). Fasting glucose, insulin, LDL, TG, leptin, hsCRP, and IL-6 levels were higher in pts with CLS-B (Table). HOMA2-IR was greater in pts with CLS-B (mean 0.63 ±0.34) versus those without CLS-B (mean 0.46 ±0.23; P=0.006). Fasting level, mean (SD)No CLS-B, N=48CLS-B +, N=52PGlucose, mg/dL73.2 (8.0)84.3 (37.6)0.04Insulin, mU/L4.3 (2.1)5.6 (2.9)0.01LDL cholesterol, mg/dL105.9 (31.0)119.4 (32.4)0.04HDL cholesterol, mg/dL71.9 (15.8)62.1 (16.1)0.003Triglycerides, mg/dL69.2 (26.3)104.9 (50.6)&amp;lt;0.001Leptin, pg/mL12.0 (10.1)22.6 (19.7)&amp;lt;0.001Adiponectin, ng/mL13.7 (5.2)10.4 (5.4)0.002hsCRP, ng/mL1.0 (1.4)2.3 (2.7)0.003 Conclusions: Breast WAT inflammation, which we have previously linked to increased aromatase activity, is associated with biochemical changes that occur in the metabolic syndrome, a risk factor for BC. Statin use is more common in patients with breast WAT inflammation and metabolic syndrome. Clinically, statin use may be a surrogate identifier of a population that is at increased baseline risk of BC. These findings may account for the variability in results of prior studies examining statin use and breast cancer risk due to elevated risk in users compared to non-users. Citation Format: Neil M Iyengar, Ayca Gucalp, Xi K Zhou, Louise R Howe, Patrick G Morris, Dilip Giri, Kotha Subbaramaiah, Priya Bhardwaj, Samuel S Park, Michael Pollak, Monica Morrow, Clifford A Hudis, Andrew J Dannenberg. Both metabolic syndrome and statin use are more common in women with breast inflammation [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P4-04-12.

Obesity and menopausal status as determinants of procarcinogenic breast inflammation.

40 Background: Chronic inflammation predisposes to several malignancies. We previously demonstrated an obesity → inflammation → aromatase axis in breast tissue. As obesity is a risk factor for postmenopausal (PoM) but not premenopausal (PreM) breast cancer (BC), we examined whether menopause and body mass index (BMI) independently impact breast white adipose tissue (WAT) inflammation. Methods: WAT was prospectively collected from patients (pts) from 04/10 to 08/13. WAT inflammation, detected by CD68 immunohistochemistry, was defined by the presence of dead or dying adipocytes surrounded by an envelope of macrophages known as crown-like structures of the breast (CLS-B). WAT area was measured with NIH Image J. Adipocyte diameter was measured with Canvas 11 Software. Endpoints were 1) CLS-B (+/-) and 2) CLS-B/cm2. Clinicopathologic associations with CLS-B were analyzed by logistic regression and Fisher’s exact test. Results: WAT (237 mastectomies, 13 abdominal reconstructions) was obtained from 238 pts; median age 48 (range 22 to 90). CLS-B occurrence and number of CLS-B/cm2 were greater in overweight/obese (BMI ≥ 25) and PoM pts compared to lean (BMI &lt; 25) and PreM pts (Table). In multivariable analyses, BMI and PoM state were independently associated with CLS-B presence (p &lt;.01 and p = .04) and greater CLS-B/cm2(p &lt; .01 and p = .01). PoM pts had larger mean adipocyte diameter (105.2 +/- 14.0 μ) than PreM pts (95.7 +/-15.6 μ; p &lt; 0.01). In pts with bilateral breast WAT and abdominal WAT, concordant CLS status (+/-) was found in 49/63 (78%) and 10/13 (77%) pts, respectively. Conclusions: Breast WAT inflammation (both presence and severity), which we have previously linked to increased aromatase activity, is associated with both increased BMI and menopause. These findings can explain the increased risk of estrogen receptor–positive BC with obesity and PoM status and may also provide targets for rational therapies. [Table: see text]

P0008 Validating the link between obesity and breast inflammation in women with breast cancer

Background In post-menopausal women, obesity is a risk factor for hormone sensitive breast cancer. We previously described crown-like structures (CLS), consisting of macrophages surrounding dead adipocytes, in the breast tissues of mice and humans. CLS were associated with increased levels of proinflammatory mediators known to be involved in carcinogenesis. We provided the first evidence of CLS in the human breast (CLS-B), which correlated with increased aromatase expression and activity. Here, we expanded our population to prospectively validate these preliminary findings. Methods White adipose tissue (WAT) was prospectively collected from women undergoing breast and reconstructive surgery. WAT was subjected to immunohistochemistry for CD68, a macrophage marker, to detect CLS-B by light microscopy. Adipocyte diameter was measured using the Canvas 11 Software. Endpoints were CLS-B presence/absence and CLS-B index (proportion of slides with CLS-B). Findings From April 2010 to February 2012, WAT (100 mastectomy and five abdominal reconstructions) was obtained from 101 American women; median age 49 years (range 26–80). CLS-B were found in 54 (53%) patients. CLS-B were seen in 9/37 (24%) normal weight patients (body mass index [BMI] μ m) compared with those without CLS-B (91.5 ± 16.1 μm; p p = 0.04). Among 25 patients with bilateral breast WAT and five patients with paired breast and abdominal WAT, concordant CLS-B findings (+/–) were seen in 80%. Interpretation Findings from this prospective study confirm that CLS-B are associated with BMI and adipocyte size. These results provide a plausible pathophysiological link between obesity and breast cancer. Abdominal WAT may be a surrogate for breast WAT inflammation; biopsies of abdominal subcutaneous WAT are more easily done, and could be performed in future clinical trials that aim to decrease breast WAT inflammation.