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

Abstract

Purpose 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. Methods Cases were categorized according to hormone receptor status as ER+, ER-, and TN (ER-, PR-, and HER2-) based on pathology data. A total of 2,104 ER+ cases, 1,070 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. Results 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/m2) 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 (WHR) with increased risk of pre-menopausal 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). Conclusions 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.

Biology and Etiology of Young-Onset Breast Cancers among Premenopausal African American Women: Results from the AMBER Consortium

“…Both risk factors showed the strongest associations among ER-negative tumors. In contrast, higher BMI showed an inverse association with young-onset disease that was strongest among ER-positive cancers, consistent with previous work(14–17,33,36). The observed differences between BMI and WHR underscore these factors as distinct measures of body fatness and suggest that abdominal adiposity, as represented by WHR, is an important factor contributing to young-onset disease(37,38).…”

“…Participants were asked questions regarding their medical and family histories as well as biologic, anthropometric, reproductive, and lifestyle exposures. For CBCS and WCHS, interviewers also measured body weight, height, and waist and hip circumferences during home interviews; for the BWHS, these measures were self-reported on questionnaires by study participants(33). Questionnaire and interview data from each study were then harmonized by the AMBER Biostatistics and Data Management core to create a central database with consistent exposure definitions across studies.…”

Correlation between obesity and prognostic/predictive parameters with emphasis on the importance of lymph node metastases in patients with invasive breast carcinoma

“…While several studies indicate that OB and OW patients more likely have a TN breast cancer [33,34], others reveal a significant relationship with ER-positive breast cancer [35]. In our series, OW was strongly associated with Luminal A molecular type (p = 0.012), which is known to have a better prognosis.…”

Type II Diabetes and Incidence of Estrogen Receptor Negative Breast Cancer in African American Women

“…We conducted analyses stratified on BMI and waist-hip ratio in order to disentangle obesity and T2D. We also stratified on menopausal status because BMI has been shown to have different associations for pre- and postmenopausal breast cancer (22,23). We used interaction terms and Wald statistics to test for multiplicative interaction, and we performed a contrast test to assess heterogeneity of associations across ER subtypes (24).…”