Obesity and Sociodemographic Factors in Luminal Breast Cancer
Luminal breast cancers represent the most prevalent molecular subtype of breast carcinoma, with Luminal A tumors generally associated with more favorable clinical outcomes than Luminal B tumors. Obesity-related inflammation and prolonged exposure to exogenous steroids have been implicated in the progression of luminal malignancies. This study evaluated 1,928 patients with Luminal A breast cancer and 1,610 patients with Luminal B breast cancer to examine associations among body mass index (BMI), age, ethnic background, menopausal status, and receptor expression, including estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Patients with Luminal B tumors demonstrated a significantly greater mean BMI compared with those with Luminal A tumors. In addition, Luminal B tumors were more frequently observed among patients of African ancestry relative to White and Hispanic populations. Multivariable analyses revealed that elevated BMI and African ancestry were independently associated with increased odds of Luminal B carcinoma, whereas postmenopausal status was associated with lower risk. Mediation analysis further indicated that BMI partially explained the association between ancestry and Luminal B disease. These findings suggest that obesity and population-specific factors may contribute to the development of more aggressive luminal breast cancer phenotypes.