Breast cancer is the most common cancer in women in US, and has the second highest mortality rate that accounts for about 25% of all cancer deaths. It has been recognized that genetic biomarkers for cancer are useful for estimating the cancer recurrence risk, and guiding targeted treatment of cancer. Since breast cancers carry a wide spectrum of gene mutations in their genomes, identification of these mutations would be promising in improving diagnosis and treatment of breast cancers. The rapid advances in Next-Generation Sequencing (NGS) technology have generated a large amount of NGS data on breast cancer genomes that makes detection and application of mutant biomarkers for breast cancer a reality. This study performed a wide survey of mutation status of cancer genes in breast cancers based on The Cancer Genome Atlas (TCGA) breast cancer data. Some frequently mutant genes in breast cancers were detected and analyzed.