Obesity and breast cancer survival in ethnically diverse postmenopausal women: the Multiethnic Cohort Study

Abstract

Breast cancer survival has been found to be lower in obese women, but few studies have evaluated ethnic variations in this association. This study examined all-cause and breast cancer-specific survival by body mass index (BMI) in the Multiethnic Cohort (MEC) study for African American, Native Hawaiian, Japanese American, Latino, and Caucasian women. Female MEC participants free of breast cancer, aged ≥ 50 years at cohort entry, and diagnosed with primary invasive breast cancer during follow-up were included in the analyses (n = 3,842). Cox proportional hazards regression was used to estimate the effect of pre-diagnostic adult BMI (<22.5, 22.5-24.9, 25.0-29.9, ≥30 kg/m 2 ) on the risk of mortality. Mean age at diagnosis was 68.8 years (range 50-89 years). During a mean follow-up of 6.2 ± 3.8 years after diagnosis, there were 804 deaths that included 376 breast cancer-specific deaths. After adjustment for breast cancer characteristics, including hormone receptor status, stage at diagnosis, and treatment, obese women had a higher risk of all-cause [hazard ratio (HR) = 1.54; 95% confidence interval (CI): 1.23, 1.91] and breast cancer-specific (HR = 1.45; 95% CI: 1.05, 2.00) mortality compared to women with high-normal BMI; however, being overweight did not affect survival. There was no evidence of ethnic differences in the BMI effect on all-cause (P interaction = 0.87) or breast cancer-specific (P interaction = 0.63) mortality. Our findings are consistent with the literature that maintaining moderate weight throughout adult life may be beneficial for breast cancer survival in women and this appears to hold for all ethnic groups.

Given breast cancer, is fat better than thin? Impact of the estrogen receptor beta gene polymorphisms

“…In previous analyses, the participants were representative of all operated breast cancer patients regarding age and hormone receptor status (ERα and PR), and we consider the study population adequately representative for Southern Sweden. Regarding the frequencies of different haplotypes within this cohort, we found a distribution similar to the distribution seen for the cohort from the Breast and Prostate Cancer Cohort Consortium, i.e., CCGC being the most common, followed by TCAT, CCAC, TCAC, CCAT, and CTAC in descending order [5]. The evident similarity in haplotype distribution between the smaller Swedish cohort and a large international cohort supports our findings in this study.…”

“…However, anthropometric measures were gathered by a research nurse in this case; thus, BMI is considered a valid variable in this study. This study is based on a predominantly Caucasian population in Sweden, and since the BMI range differs widely internationally and according to ethnicity [5], the results may not be representative for all breast cancer populations.…”

Obesity and Risk of Breast Cancer Mortality in Hispanic and Non-Hispanic White Women: The New Mexico Women's Health Study

“…2,5 Several recent prospective studies have examined the relationship between obesity and breast cancer-specific mortality and reported relative risks ranging from 1.45 to 1.57. 5,11,12 The purpose of the present analyses was to determine if obesity (BMI > 30 kg/m 2 ) is associated with breast cancer-specific, all-cause, and non-breast cancer mortality, and if these associations differ by Hispanic versus nonHispanic white (NHW) ethnicity based on data for participants in the New Mexico Women's Health Study (NMWHS).…”

Effect of Obesity on Estradiol Depletionin Postmenopausal Women With Hormone-Sensitive Early Breast Cancer Treated Withadjuvant Anastrazole.

“…15 It is a well-known fact that obesity increases total-body aromatization which leads to increased serum estrogen level when compared with non-obese 10,16, 17 . Obesity was found to have an impact on the effect of AIs ,specially Anastrazole, in patients with breast cancer.…”