Abstract
Interleukin 6 (IL-6) and its receptors are expressed in approximately half of breast cancer (BC) tissues, and high serum IL-6 levels are associated with poor prognosis. African American (AA) patients with BC have higher serum IL-6 levels compared to Caucasians, suggesting additional risk of disease-related complications in AAs. The purpose of this study was to compare IL-6 complex biomarkers in AA women with and without a history of BC. We conducted a secondary analysis of phenotypic data from two studies of weight loss in AA women with and without a history of BC who had similar age and adiposity. Biomarkers analyzed included tumor necrosis factor alpha (TNF-α), IL-6, IL-6 soluble receptor (IL6sr), and soluble glycoprotein 130 (GP130); IL6sr and GP130 were newly analyzed for this study. TNF-α levels were 1.86 times higher in the BC group (N = 7) compared to those without BC (N = 10; p < 0.001) despite similar age, weight, and body mass index. GP130 levels tended to be higher in women with BC; IL-6 and Il-6 sr were not different between groups. There was a strong correlation between GP130 and TNF-α (r = .638; p = .006) in the group overall. High TNF-α levels in the BC group and a strong correlation between GP130 and TNF-α in the overall group suggest the presence of IL-6 complex initiated TNF-α production. Further study is needed to evaluate IL-6 reduction through a variety of approaches, including weight loss and anti-IL-6 therapies, which may ultimately implicate the reduction of IL-6 complex associated BC-specific recurrence and mortality.