Figure 1.Combination of gene expression and DNA methylation profiling might improve prognosis and prediction to treatment response for breast cancer. Tumor tissue is composed of two major components: the tumoral epithelial cells and the tumor microenvironment that includes the extracellular matrix (ECM), immune cells and tumor-associated fibroblasts (TAFs). While gene expression profiling highlights majorly markers from the tumor component, DNA methylation profiling is more sensitive for the detection of markers from the microenvironment. Therefore, together, gene expression and DNA methylation markers should bring a more complete view of the tumor tissue, this might help for breast cancer patient management.