Increased Brahma-related Gene 1 Expression Predicts Distant Metastasis and Shorter Survival in Patients with Invasive Ductal Carcinoma of the Breast

Background: Previous studies have demonstrated aberrant Brahma-related gene 1 (BRG1) expression in various tumor types. Increased BRG1 expression has recently been shown to correlate with aggressive oncogenic behavior in many different types of human cancer. However, the role of BRG1 in breast cancer development and progression is not fully understood. Materials and Methods: We evaluated BRG1 expression in 224 patients with invasive ductal carcinoma (IDC) of the breast using tissue microarray samples and immunohistochemistry. We also investigated whether BRG1 expression status is associated with clinicopathological characteristics and outcomes of patients with IDC. Results: Among the 224 patients with IDC, 37.5% (84/224) exhibited high BRG1 expression. IDC exhibited significantly higher BRG1 expression compared to ductal carcinoma in situ (p=0.009) and normal breast tissue (p=0.005). High BRG1 expression in IDC significantly correlated with higher histological grade (p=0.035) and presence of distant metastasis (p=0.002). Furthermore, high BRG1 expression was an independent factor for predicting distant metastasis (relative risk=4.079; p=0.007). In addition, high BRG1 expression predicted shorter overall (p=0.011) and recurrence-free (p=0.003) survival in patients with IDC. In particular, BRG1 had a significant prognostic value in predicting recurrence-free survival of patients with IDC with lymph node metastasis or stage III disease. Conclusion: BRG1 is involved in the progression and metastasis of breast cancer and can serve as a novel biomarker predictive of distant metastasis and patient outcomes.